WorldWideScience
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Study on Tei index of right ventricular by tissue doppler imaging and the observation point selection  

International Nuclear Information System (INIS)

Objective: To explore the right ventricular (RV) Tei index in patients with pulmonary hypertension (PH) by tissue Doppler imaging (TDI), and to explore more accurate observation point to obtain Tei index of right ventricular. Methods: Assessment of RV Tei index values was performed in 95 patients with PH and 32 normal subjects. The 95 patients were grouped into 3 groups according to the severity of PH. Tei index values were obtained by TDI measurement from three observation points, the anterior tricuspid and septal tricuspid attachment points in the apical 4-chamber view and the posterior tricuspid attachment point in parasternal right heart 2-chamber review. Results: (1) RV Tel index values were measured at the three points of PH was higher than the normal significantly (P<0.05). (2) RV Tei index values of the three PH groups at he anterior tricuspid attachment had significant difference each other (P<0.05). RV Tei index values of low-grade and medium-grade PH groups at septal tricuspid and posterior tricuspid had no significant difference, but that of high-grade PH group were higher than the low-grade and medium-grade PH group. Conclusion: RV Tei index value was significantly increased in PH patients. The Tei index value measured by TDI at anterior tricuspid attachment point in apical 4-chamber view was better than that at septal tricuspid attachment point in the apical 4-chamber view and posterior' attachment of parasternal right heart 2-chamber. (authors) right heart 2-chamber. (authors)

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Tissue Doppler Tei index estimation of global function of right ventricle in patients with hypertension  

International Nuclear Information System (INIS)

Objective: An evaluation of tissue Doppler Tei index in estimating global function of right ventricle in patients with hypertension. Methods: Twenty patients with hypertension and 20 health individuals as the control group were enrolled in the study. The tricuspid annular motion was obtained by pulse-wave Doppler tissue imaging (PW-DTI). The peak systolic velocity (Sm) and its integral of velocity and time (Sm-VTI), as well as the peak velocity at early diastole(et) and at late diastole (at) were measured respectively. ICT, ET and IRT of right ventricle were taken with ECG(L II). Tel index was calculated. Results: 1 The Tei index of RV in hypertension group was significantly higher than that of the control group(0.63 ± 0.14 VS 0.50 ± 0.07. Pt and et/at of the study group were significantly lower than that of the contral group. (Sm: 12.44±3.43 vs 14.66±2.38 cm/s; Pt/at: 11.37±3.58 vs 17.97±3.95 cm/s; Pt/at: 0.83±0.23 vs 1.44±0.48; Pt and et/at(Sm-VTI, r= -0.368, P t, r=-0.507, Pt/at, r= -0.425, P<0.01). Conclusion: The Tei25, P<0.01). Conclusion: The Tei index of RV obtained by PW-TDI was an easy method with high sensitivity, which may be applied to assess the global function of RV in patients with hypertension. (authors)

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Determinación de los valores del índice de Tei (índice de performance miocárdico) en caninos con insuficiencia cardiaca, evaluados mediante ecocardiografía Doppler / Determination of left ventricular tei index (index of myocardial performance) in dogs with heart failure by Doppler echocardiography  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Ha sido demostrado que el índice de Tei del ventrículo izquierdo (índice de performance miocárdico) puede ser de utilidad clínica para estimar la función de este ventrículo, incluyendo tanto la función sistólica como la diastólica. El propósito de este estudio fue evaluar el índice de Tei en perros [...] con falla cardiaca (FC). El índice de Tei incrementó significativamente en perros con FC, comparado con caninos sanos. En conclusión, el estudio demostró que el índice de Tei fue medible en perros y no está influenciado por la frecuencia cardiaca, la edad ni el peso. Abstract in english The left ventricular (LV) Tei index (index of myocardial performance) has been demonstrated to be clinically useful in estimating comprehensive LV function, including the systolic and diastolic performances. The purposes of this study were to evaluate the LV Tei index in dogs with Heart Failure (HF) [...] . The LV Tei index significantly increased in dogs with HF compared with normal dogs. In conclusion, our study demonstrated that the LV Tei index was measurable in dogs and not influenced by heart rate, age and body weight. The LV Tei index significantly increased in dogs with HF.

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

2010-12-01

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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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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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 Abstract in english 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 hemod [...] ialysis 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

Silvio Henrique, Barberato; Roberto, Pecoits Filho.

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.

2010-06-01

7

Right Ventricular Tissue Doppler in Space Flight  

Science.gov (United States)

The presentation slides review normal physiology of the right ventricle in space, general physiology of the right ventricle; difficulties in imaging the heart in space, imaging methods, tissue Doppler spectrum, right ventricle tissue Doppler, and Rt Tei Index.

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

2010-01-01

8

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  

OpenAIRE

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 p...

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

2006-01-01

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Phase relation in the systems A2TeI6-Tl2TeI6 and A2TeBr6-A2TeI6 (A - K, Rb, Cs, Tl(I))  

International Nuclear Information System (INIS)

By the methods of differential thermal and x-ray phase analyses character of physicochemical interaction in the systems K2TeI6-Tl2TeI6, Rb2TeI6-Tl2TeI6, Cs2TeI6-Tl2TeI6, K2TeI6-K2TeI6, Rb2TeI6-Rb2TeI6, Cs2TeI6-Cs2TeI6, Tl2TeI6-Tl2TeI6 is studied. Phase diagrams are plotted. In all systems formation of continuous series of solid solutions on the basis of initial ternary compounds is detected. Relationship between A+ and Br- or I- ion sizes is a factor determining structural type of the compounds

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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.

2006-12-01

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Welcome to the TEI’10 Proceedings  

DEFF Research Database (Denmark)

We welcome you to the proceedings of the 4th ACM International Conference on Tangible, Embedded, and Embodied Interaction -- TEI'10, held in Cambridge, Massachusetts, on the 25th -27th of January 2010. TEI'10 continues the pursuit of key areas of innovation in respect to tangible, embedded, and embodied interactions. These concerns include the interlinking of digital and physical worlds through tangible and embodied interaction and the computational augmentation of everyday objects and environments in new ways through embedded technologies. Research and practice in these innovative areas lead to works of tangible interfaces, graspable interfaces, physical computing, whole-body interaction, gesture-based interfaces, and interactive surfaces. Designing such systems requires interdisciplinary thinking as their creation not only encompasses software, electronics, and mechanics, but also form, aesthetics, and social impact. The high quality, original, and diverse works in these proceedings is a testament to thegrowth and importance of the field of tangible computing. The call for papers attracted 160 submissions from approximately 20 countries spanning Africa, Asia, Canada, Europe, and the United States. All submissions were peer and blind reviewed and received at least three independent expert reviews. In total, 54 papers were accepted for an acceptance rate of 34%. The papers are a mix of 2, 4, 8 pages in length. From these contributions, the program at the conference includes 16 long talks, 8 short talks, 1 short talk and a demo, 22 demos, and 7 posters. We are proud to continue the tradition of a plenary session for all talks, demos and posters. The paper sessions are organized along five themes. Bridging the Physical and Digital Worlds is at the center of tangible computing investigations that explore the intersections of computation and physicality. Toolkits and Enabling Technologies explores the functionality of applications and technologies for users and the tools for designers and developers. Physical Interactions, Perspectives, and Design Techniques represent the emerging and refined thinking in the field that investigates embodiment, reflections and frameworks, and emerging techniques. Materials, Garments and Lights uncovers the serious investigations into new materials and expressions for tangible computing. Lastly, Learning through Physical Interaction contributes to the invaluable intersections between tangible computing and learning. In addition, the demonstrations and posters session gives concrete and vibrant evidence for the serious and diverse research in the field. We are also proud to include innovations in the conference program this year. A new track was created known as Explorations aimed at attracting thought provoking, evocative, visually and sensually rich work by a diverse group of creators. 46 submissions were received from which an expert jury accepted 10 contributions. These contributions are interwoven into the papers and demonstration tracks at the conference. Another new track is Studios, a series of 21 workshop sessions open to all conference participants that offer novel hands-on experiences ranging from the exploration of new development toolkits, to prototype design techniques, and the use of emerging or traditional materials in creatively applied way. Lastly, the Graduate Student Consortium reflects the essential need for the participation and development of new scholars in the areas of tangible computing. 38 submissions were received and 13 contributions were accepted after blind reviews by at least three independent and expert reviewers per submission.

Pederson, Thomas; Shaer, Orit

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 pathway-specific regulatory genes, tei15* and tei16*, are the master switches of teicoplanin production in Actinoplanes teichomyceticus.  

Science.gov (United States)

Pathogenic antibiotic-resistant bacteria are an unprecedented threat to health care worldwide. The range of antibiotics active against these bacteria is narrow; it includes teicoplanin, a "last resort" drug, which is produced by the filamentous actinomycete Actinoplanes teichomyceticus. In this report, we determine the functions of tei15* and tei16*, pathway-specific regulatory genes that code for StrR- and LuxR-type transcriptional factors, respectively. The products of these genes are master switches of teicoplanin biosynthesis, since their inactivation completely abolished antibiotic production. We show that Tei15* positively regulates the transcription of at least 17 genes in the cluster, whereas the targets of Tei16* still remain unknown. Integration of tei15* or tei16* under the control of the aminoglycoside resistance gene aac(3)IV promoter into attB?C31 site of the A. teichomyceticus chromosome increased teicoplanin productivity to nearly 1 g/L in TM1 industrial medium. The expression of these genes from the moderate copy number episomal vector pKC1139 led to 3-4 g/L teicoplanin, while under the same conditions, wild type produced approximately 100 mg/L. This shows that a significant increase in teicoplanin production can be achieved by a single step of genetic manipulation of the wild-type strain by increasing the expression of the tei regulatory genes. This confirms that natural product yields can be increased using rational engineering once suitable genetic tools have been developed. We propose that this new technology for teicoplanin overproduction might now be transferred to industrial mutants of A. teichomyceticus. PMID:25104028

Horbal, Liliya; Kobylyanskyy, Anton; Truman, Andrew W; Zaburranyi, Nestor; Ostash, Bohdan; Luzhetskyy, Andriy; Marinelli, Flavia; Fedorenko, Victor

2014-11-01

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Myocardial Motion Analysis for Determination of Tei-Index of Human Heart  

Directory of Open Access Journals (Sweden)

Full Text Available The Tei index, an important indicator of heart function, lacks a direct method to compute because it is difficult to directly evaluate the isovolumic contraction time (ICT and isovolumic relaxation time (IRT from which the Tei index can be obtained. In this paper, based on the proposed method of accurately measuring the cardiac cycle physical phase, a direct method of calculating the Tei index is presented. The experiments based on real heart medical images show the effectiveness of this method. Moreover, a new method of calculating left ventricular wall motion amplitude is proposed and the experiments show its satisfactory performance.

Jianwei Zhang

2010-12-01

15

Effects of isoflurane on Tei-index of myocardial performance in healthy dogs  

OpenAIRE

Recently, the Tei-index, a noninvasive index that combines systolic and diastolic time intervals, has been proposed to assess global cardiac performance. However, the effects of isoflurane on the Tei-index have not been characterized. This study aimed at studying the effects of 1.0 minimal alveolar concentration isoflurane anesthesia on the pre-ejection period (PEP), left ventricular ejection time (LVET), PEP/LVET ratio, isovolumic relaxation time (IVRT), stroke index (SI), cardiac index (CI)...

Sousa, Marlos Gonc?alves; Carareto, Roberta; De-nardi, Andrigo Barboza; Brito, Fa?bio L. C.; Nunes, Newton; Camacho, Aparecido Antonio

2007-01-01

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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

17

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

18

Synthesis and structure-activity relationships of TEI-9647 derivatives as Vitamin D3 antagonists.  

Science.gov (United States)

The Vitamin D(3) lactone analogues, (23S)- and (23R)-25-dehydro-1alpha-hydroxyvitamin D(3)-26,23-lactone (TEI-9647 and TEI-9648) are antagonists of the 1alpha,25-dihydroxyvitamin D(3) (1alpha,25-(OH)(2)D(3)) nuclear receptor (VDR)-mediated differentiation of human leukemia (HL-60) cells. In order to clarify the structure-Vitamin D antagonistic activity relationship, we paid attention to the unique lactone moiety of TEI-9647 and TEI-9648: alpha-exo-methylene-gamma-lactone structure. We synthesized the exo-methylene-modified analogues (methylene saturated, endo-methylene, methylene-deleted, methyl-substituted, dimethyl-substituted, methylene-replaced with dimethyl and cyclopropane) and oxygen-modified analogues (oxygen atom replaced with nitrogen and carbon atom) by convergent method using palladium-catalyzed coupling reaction or direct modification of VD(3) skeleton. The antagonistic activity in HL-60 cell differentiation evaluating system of these analogues revealed that any exo-methylene-modified analogues and nitrogen analogue did not have the antagonistic activity, on the other hand carbon analogue did show. The results suggest that "alpha-exo-methylene carbonyl" structure of VD(3) side-chain is crucial for antagonistic activity. The structure is integral building block of many natural products which have interesting biological and it is thought that Michael-type addition of alpha-exo-methylene carbonyl structure with protein nucleophiles such as cysteine would play an important role for the activities. According to this theory, Michael-type reaction of TEI-9647 and TEI-9648 with cysteine residue in protein related to VDR/VDRE-mediated genomic actions such as VDR would be essential step of the antagonistic action. PMID:15225742

Takenouchi, Kazuya; Sogawa, Ryo; Manabe, Kenji; Saitoh, Hiroshi; Gao, Qingzhi; Miura, Daishiro; Ishizuka, Seiichi

2004-05-01

19

Doppler tomography  

International Nuclear Information System (INIS)

The finding that cancer may have different Doppler characteristics from other tissues and vessels has prompted some interest in Dopper evaluation of breasts. In an effort to obtain sequences of Doppler images suitable for complete breast images, the authors have tested methods of Doppler tomography. Doppler tomography was performed in phantoms in which fluid was flowing in several tubes. The backscatter CW Doppler signal from a 2 MHz carrier was measured for 128 samples along 200 profiles taken at equispaced angles of view around the phantom. The RF signal was mixed to base stand, low pass filtered, and A/D converted to 10 KHz for subsequent computer analysis. The Doppler power in a specified frequency band was used to eliminate number of particles moving within a certain velocity range. Reconstructed images were obtained with and without flow in tubes within excised human breast. Images proportional to number of particles flowing at velocities greater than a certain velocity were of good quality. The results show that Dopper tomography is a distinct possibility even though the vector nature of Doppler shift causes some inconsistencies in the data

20

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

OpenAIRE

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 ...

Pilakouta, Mirofora

2011-01-01

21

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

OpenAIRE

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

22

Effect of the novel prostaglandin A1 derivative TEI-6363 on ROS17/2.8 cell differentiation in vitro.  

Science.gov (United States)

The effect of TEI-6363 (5-[E-4-N,N-dimethylaminophenylmethylene]-4-hydroxy-2-[1-methyl imidazole-2-ilthio]-4-[4-phenylbutyl]-2-cyclopentenone), a chemically synthesized prostaglandin A1 derivative, on cell proliferation and osteoblastic differentiation was investigated concurrently. ROS17/2.8 cells (a rat osteosarcoma-derived cell line) were treated with TEI-6363 at two concentrations, 10(-7) and 10(-6) M, and viable cells were counted to assess cytotoxic effects and determine the growth curve. After 96 h of treatment, there was no evidence of any effect of TEI-6363 on cell viability at either concentration. However, a clear inhibitory effect on cell proliferation was observed after treatment with 10(-6) M TEI-6363 for 24 h or longer. A pulse-treatment experiment showed that TEI-6363 induced the inhibition of proliferating ROS17/2.8 cells 24 h after addition. The inhibition of proliferation was associated with G1-arrest demonstrated by flow cytometric analysis, and incorporation of [3H]thymidine by ROS17/2.8 cells was decreased. Osteoblastic differentiation (assessed on the basis of increased alkaline phosphatase activity and collagen synthesis) was induced by TEI-6363 treatment at 10(-6) M following G1-arrest and inhibition of cell proliferation. These results suggest that TEI-6363 arrested the cell cycle of ROS17/2.8 cells at the G1 phase and induced osteoblastic differentiation. These results did not appear to be dependent on a marked cytotoxic effect. PMID:10952074

Miura, D; Uno, H; Azuma, Y; Ohta, T; Kiyoki, M; Izawa, Y

2000-07-01

23

Revamping the LIS Curriculum in the Department of Library Science and Information Systems at the TEI of Athens  

Science.gov (United States)

In the context of the changes in the information environment, the LIS department of the TEI of Athens developed a curriculum intending to incorporate the changes taking place in the information field's knowledge base, based on a literature review, the comparison of similar curricula in LIS schools worldwide and the demands of the students and the…

Moniarou-Papaconstantinou, Valentini; Chatzimari, Stella; Tsafou, Stamatina

2008-01-01

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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

25

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.

26

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

CERN Document Server

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

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

28

Image-derived input functions for PET brain studies  

International Nuclear Information System (INIS)

To assess the robustness of a previously introduced method to obtain accurate image-derived input functions (IDIF) for three other tracers. Dynamic PET and online blood data of five repeat [11C]PIB (Pittsburgh Compound-B) ([11C]PIB), six repeat (R)-[11C]verapamil, and ten single (R)-[11C]PK11195 studies were used. IDIFs were extracted from partial volume corrected scans using the four hottest pixels per plane method. Results obtained with IDIFs were compared with those using standard online measured arterial input functions (BSIF). IDIFs were used both with and without calibration based on manual blood samples. For (R)-[11C]verapamil, accurate IDIFs were obtained using noncalibrated IDIFs (slope 0.96±0.17; R 2 0.92±0.07). However, calibration was necessary to obtain IDIFs comparable to the BSIF for both [11C]PIB (slope 1.04±0.05; R 2 1.00±0.01) and (R)-[11C]PK11195 (slope 0.96±0.05; R 2 0.99±0.01). The need for calibration may be explained by the sticking property of both tracers, indicating that BSIF may be affected by sticking and therefore may be unreliable. The present study shows that a previously proposed method to extract IDIFs is suitable for analysing [11C]PIB, (R)-[11C]verapamil and (R)-[11C]PK11195 studies, thereby obviating the need for online arterial sampling. (orig.)

29

The Petrology of the Wong Tei Tung Stone Tool Manufacturing Site, Sham Chung, Hong Kong Sar, China  

Directory of Open Access Journals (Sweden)

Full Text Available The Wong Tei Tung archaeological site was discovered in 2003. Two periods have been proposed: an earlier period dating to around 40,000 years bp, and a later period dating to around 7000 years bp, but these dates should be treated cautiously. Initially, reported research found a few traits of the Wong Tei Tung assemblage to be similar to South-east Asia lithics, especially the short axe and Sumatralith cores. It has been reported that the Wong Tei Tung assemblage is a lithic cluster of certain 'techno-complex' implements rather than an archaeological culture; it offers a glimpse of lithic manufacturing in adaptation to its particular coastal environment. The published evidence points to a production of stone tools that considerably exceeded anticipated immediate local need. It is likely, therefore, that products from the site were distributed widely across the Zhujiang Estuary (Pearl River area and beyond (Fig. 1: map. This article presents the results of initial investigations into the geological setting of the site; provides new petrographic descriptions using data obtained from thin sections and geochemical analyses; and makes tentative comparisons with similar archaeological stone tool manufacturing sites in Britain.

Vin Davis

2009-09-01

30

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

31

Doppler Optical Coherence Tomography  

Science.gov (United States)

This chapter describes Doppler optical coherence tomography (D-OCT). This is an imaging modality that combines Doppler principles with optical coherence tomography to image tissue structure and blood flow velocity simultaneously. We will review the principle and technology of D-OCT and illustrate a few examples of its applications.

Chen, Zhongping; Liu, Gangjun

32

Cosmology with Doppler Lensing  

CERN Document Server

Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities. Objects falling into an overdensity appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts. This effect dominates over the usual gravitational lensing magnification at low redshift. Doppler lensing is a promising new probe of cosmology, and we explore in detail how to utilize the effect with forthcoming surveys. We present cosmological simulations of the Doppler and gravitational lensing effects based on the Millennium simulation. We show that Doppler lensing can be detected around stacked voids or unvirialised over-densities. New power spectra and correlation functions are proposed which are designed to be sensitive to Doppler lensing. We consider the impact of gravitational lensing and intrinsic size correlations on these quantities. We compute the correlation functions and forecast the errors for realistic forthcoming surveys, providing predictions for constraints...

Bacon, David J; Clarkson, Chris; Bolejko, Krzysztof; Maartens, Roy

2014-01-01

33

COMPONETES VOLÁTEIS E SABOR DE MAMÃO (Carica papaya: UMA REAVALIAÇÃO  

Directory of Open Access Journals (Sweden)

Full Text Available

RESUMO: Os componentes voláteis de duas cultivares de mamão (Solo e Formosa da mesma região geográfica (Bahia, e da mesma cultivar (Solo de duas regiões geográficas distintas (Bahia e Pará, examinados durante o ano de 1991, mostraram uma grande variabilidade, o que exigiu uma repetição do estudo para verificar a variação em dois anos consecutivos. A cultivar Solo continuou apresentando uma alta porcentagem de linalol (até 94%, e o segundo constituinte mais abundante foi o óxido trans de linalol. Os lotes analisados da cultivar Formosa mostraram maior variabilidade, porém bem menor do que no ano de 1991. Esta cultivar mostrou uma maior proporção do óxido cis, e linalol foi o segundo componente majoritário. Em relação aos ésteres de metila, butanoato variou de traços até 17%, crotonato não foi detectado, e hexanoato o foi no máximo como traços. A composição de voláteis da cultivar Solo da Bahia e do Pará não diferiu significativamente. A análise descritiva quantitativa mostrou que a cultivar Solo possui aroma floral com sabor mais doce e de néctar. A cultivar Formosa apresentou um sabor mais amargo e mais aguado, com notas de verde. Não houve diferenças significativas no aroma dos mamões Solo e da Bahia e do Pará; entretanto, o do Pará foi considerado com um sabor de néctar mais acentuado. PALAVRAS-CHAVE: Aroma; compostos voláteis; análise sensorial; cromatografia gasosa; mamão.

MARIA REGINA BUENO FRANCO

2009-07-01

34

Testing radon mitigation techniques in a pilot house from B?i?a-?tei radon prone area (Romania).  

Science.gov (United States)

This work presents the implementation and testing of several radon mitigation techniques in a pilot house in the radon prone area of B?i?a-?tei in NW part of Romania. Radon diagnostic investigations in the pilot house showed that the main source of radon was the building sub-soil and the soil near the house. The applied techniques were based on the depressurization and pressurization of the building sub-soil, on the combination of the soil depressurization system by an electric and an eolian fans. Also, there was made an application of a radon barrier membrane and a testing by the combination of the radon membrane by the soil depressurization system. Finally, the better obtained remedial efficiency was about 85%. PMID:25483354

Cosma, Constantin; Papp, Botond; Cuco? Dinu, Alexandra; Sainz, Carlos

2015-02-01

35

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

36

Laser Doppler blood flowmetry  

International Nuclear Information System (INIS)

Laser Doppler flowmetry is a method for continuous quantification of microvascular perfusion. During the measurements, low energy helium-neon laser light is applied to the tissue. Doppler shifted light reflected out of the tissue is then analyzed, and the shift of frequency quantitated. The output signal is proportional to the flux of blood cells in the measuring tissue of some few mm3. Laser Doppler flowmetry can easily be applied for measurements on skin and surgically exposed surfaces. Measurements can also be obtained through an endoscope. Measuring probes of diameter 0.5 mm can be introduced into tissues to quantitate microvascular perfusion within tissues. The article reviews the theory of laser Doppler flowmetry measurements, presents methodological aspects, and gives examples of clinical application. 20 refs., 4 figs

37

Research & Medical Doppler platform  

OpenAIRE

A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables the diagnosis of intracranial vessels and the assessment of the blood flow. The device can display a color map of flow velocities in time-depth domain and a spectrogram of Doppler signal obtained at a selected depth. The system offers the multigate processing which allows to display simultaneously a number of spectrograms and to reconstruct a flow velocity profile. The digital signal processing i...

Lewandowski, Marcin; Walczak, Mateusz; Karwat, Piotr; Witek, Beata; Nowicki, Andrzej; Kar?owicz, Pawe?

2012-01-01

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Right ventricular tissue Doppler assessment in space during circulating volume modification using the Braslet device  

Science.gov (United States)

Introduction: This joint US-Russian work aims to establish a methodology for assessing cardiac function in microgravity in association with manipulation of central circulating volume. Russian Braslet-M (Braslet) occlusion cuffs were used to temporarily increase the volume of blood in the lower extremities, effectively reducing the volume in central circulation. The methodology was tested at the International Space Station (ISS) to assess the volume status of crewmembers by evaluating the responses to application and release of the cuffs, as well as to modified Valsalva and Mueller maneuvers. This case study examines the use of tissue Doppler (TD) of the right ventricular (RV) free wall. Results: Baseline TD of the RV free wall without Braslet showed early diastolic E' (16 cm/s), late diastolic A' (14 cm/s), and systolic S' (12 cm/s) velocities comparable with those in normal subjects on Earth. Braslet application caused 50% decrease of E' (8 cm/s), 45% increase of A', and no change to S'. Approximately 8 beats after the Braslet release, TD showed E' of 8 cm/s, A' of 12 cm/s, and S' of 13 cm/s. At this point after release, E' did not recover to baseline values while l A' and S' did recover. The pre-systolic cross-sectional area of the internal jugular vein without Braslet was 1.07 cm 2, and 1.13 cm 2 10 min after the Braslet was applied. The respective cross-sectional areas of the femoral vein were 0.50 and 0.54 cm 2. The RV myocardial performance Tei index was calculated by dividing the sum of the isovolumic contraction time and isovolumic relaxation time by the ejection time ((IVCT+IVRT)/ET); 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 terrestrial subjects and temporarily become greater than 0.4 during the dynamic Braslet release portion of the study. Conclusions: TD modality was successfully implemented in space flight for the first time. TD of RV revealed that the Braslet influenced cardiac preload and that fluid was sequestered in the lower extremity interstitial and vascular space after only 10 min of application. This report demonstrates that Braslet application has an effect on RV physiology in long-duration space flight based on TD, and that this effect is in part due to venous hemodynamics.

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

2011-05-01

39

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

40

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.)

41

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

42

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

43

Doppler superheterodyne -vastaanotin  

OpenAIRE

Doppler-ilmiö aiheuttaa kuullussa taajuudessa vääristymän, joka voidaan havaita taajuuden, aallonpituuden tai vaiheen muutoksena alkuperäisestä signaalista. Vääristymän suuruuteen ja suuntaan vaikuttaa se, pieneneekö vai suureneeko signaalilähteen ja vastaanottimen välinen etäisyys, sekä nopeus, jolla ne liikkuvat toisiinsa nähden. Tätä ilmiötä on mahdollista hyödyntää radiolähettimen paikantamisessa. Opinnäytetyön tavoitteena oli suunnitella ja toteuttaa protolev...

Taskila, Pekka

2011-01-01

44

Ultrasonic colour Doppler imaging  

DEFF Research Database (Denmark)

Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been found to be of great value in assessing blood flow in many clinical conditions. Although the method for obtaining the velocity information is in many ways similar to the method for obtaining the anatomical information, it is technically more demanding for a number of reasons. It also has a number of weaknesses, perhaps the greatest being that in conventional systems, the velocities measured and thus displayed are the components of the flow velocity directly towards or away from the transducer, while ideally the method would give information about the magnitude and direction of the three-dimensional flow vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new techniques that seek to overcome the vector problem mentioned above are described. Finally, some examples of vector velocity images are presented.

Evans, David H.; Jensen, JØrgen Arendt

2011-01-01

45

Relationship between tei index and left ventricular geometric patterns in a hypertensive population: a cross-sectional study  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The relationship between Tei Index (TI and left ventricular (LV geometric patterns has not been previously well described. The present study therefore set out to describe the nature of this relationship if any, and to also assess whether a relationship exists between the geometric patterns and LV ejection fraction (LVEF so as to establish a basis for comparison. Methods The study was carried out in the echocardiography laboratory of Aminu Kano Teaching Hospital (AKTH in Kano, North-Western Nigeria. The study was cross-sectional in design. Hypertensive subjects referred for echocardiography to AKTH were serially recruited from October 2008 to September 2009. TI was defined as the sum of isovolumic contraction and relaxation times divided by the ejection time, and values of LV TI Results A total of 142 subjects were recruited into the study. The prevalence of abnormal TI (26.8%; 38 persons in the total population was lower than that of reduced LV ejection fraction ( Conclusion This study has found that LV geometric patterns and LVEF were not associated with TI in hypertensives, but there was strong association between LV geometric patterns and LVEF. TI was found to be dependent on HR.

Karaye Kamilu M

2011-07-01

46

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.

47

Laser double Doppler flowmeter  

Science.gov (United States)

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

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

2014-05-01

48

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

49

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

50

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

51

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.; Pedersen, P. C.

1995-01-01

52

Principles of doppler tomography  

International Nuclear Information System (INIS)

This paper shows how the radon transform can be used to determine vector fields. A scheme to determine the velocity field of a moving fluid by measurements with a continuous doppler signal is suggested. When the flow is confined to a bounded domain, as is the case in most applications, it can be uniquely decomposed into one gradiental and one rotational part. The former vanishes if the fluid is incompressible and source-free, and the latter can be completely reconstructed by the methods proposed in this paper if the domain is simply connected. Special attention is paid to laminar flow in a long cylindrical vessel with circular cross-section. Under such conditions the flow profile becomes parabolic, which makes the vessel recognizable as a typical 'N-shaped' pattern in an image describing the rotation of the velocity field. The vessel yields the same doppler tomographic pattern, no matter how it is sectioned. The ideas presented should be applicable also when studying the flow in blood vessels, even if the flow profile in these is not quite parabolic. The discrepancies only make the 'N-shape' somewhat distorted

53

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 (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of 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

54

A Whiter Shade of Grey: A new approach to archaeological grey literature using the XML version of the TEI Guidelines  

Directory of Open Access Journals (Sweden)

Full Text Available This article has arisen through the author's interest in two contemporary issues within archaeology: the production and dissemination of grey literature and the potential of XML. Grey literature is examined, with specific reference to unpublished reports literature produced in the present climate of developer-funded archaeology in England. There are concerns about the accessibility of this literature, both from within and beyond the archaeological profession. The vast majority of reports are word-processed and then printed in hard-copy format for limited distribution. The original, digital document however, has largely been seen as a by-product. Awareness of the importance of these digital reports, and their preservation must be raised. Electronic means of delivery and dissemination via the World Wide Web offer huge potential and present opportunities for new ways of working. Archaeology is not alone in seeking to promote the accessibility of grey literature; indeed there are many disciplines that have created online initiatives aiming to do just this, utilising a variety of means and a range of electronic file formats. The use of XML technology appears to offer many advantages over traditional formats, such as word-processed, PDF and even (XHTML files, particularly with regard to the manipulation and presentation of encoded electronic text. Increasingly, XML technology is being used for electronic delivery and dissemination and the pros and cons of so doing are discussed in this article. This theme has been developed by the author through a 'proof of concept' practical case study of three unpublished grey literature archaeology reports from the North Yorkshire Historic Environment Record. XML documents have been created from the original word-processed electronic reports by the manual application of XML markup, the methodology for which was devised following the XML version of the Text Encoding Initiative's TEI P4 Guidelines. The level of detail to which the reports' structure and content has been encoded has been influenced principally by a review of user needs identified by recent national surveys and the potential for export of data for the population of other heritage datasets. Through the application of CSS and XSL stylesheets, the case study demonstrates how the reports and their content may be displayed in different ways and how selected data may be extracted from the text for input into other systems, such as Historic Environment Records and the OASIS Project database. The author came to this project as a novice in the use of XML and XSLT, and learnt far more as the case study progressed. Whilst it has been possible to achieve the desired aims, it is acknowledged that this is just a starting point; more advanced users of XSLT will, no doubt, be able to produce more sophisticated ways of applying styling and transformation. Nevertheless, it is hoped that this exploration of the potential of archaeological document markup will encourage others to use and experiment with XML. The practical elements of this paper demonstrate how XML and XSLT have the power and flexibility to open up new possibilities for the presentation of grey literature on the Web, and for the repurposing of report content, above and beyond those achievable with the proprietary file formats favoured at present. There is national interest in, and call for, the development of new methods of electronic publication for archaeological reports; it is hoped that this article will contribute to this debate.

Gail Falkingham

2005-04-01

55

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

Energy Technology Data Exchange (ETDEWEB)

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.

Silva, N.A. da [Institute of Biophysics and Biomedical Engineering, University of Lisbon (Portugal); Institute of Neurosciences and Medicine - 4, Juelich (Germany); Herzog, H., E-mail: h.herzog@fz-juelich.de [Institute of Neurosciences and Medicine - 4, Juelich (Germany); Weirich, C.; Tellmann, L.; Rota Kops, E. [Institute of Neurosciences and Medicine - 4, Juelich (Germany); Hautzel, H. [Department of Nuclear Medicine (KME), University of Duesseldorf, Medical Faculty at Research Center Juelich, Juelich (Germany); Almeida, P. [Institute of Biophysics and Biomedical Engineering, University of Lisbon (Portugal)

2013-02-21

56

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

57

Doppler indicates of uterine artery Doppler velocimetry by placental location  

International Nuclear Information System (INIS)

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

58

COLLINARUS: collection of image-derived non-linear attributes for registration using splines  

Science.gov (United States)

We present a new method for fully automatic non-rigid registration of multimodal imagery, including structural and functional data, that utilizes multiple texutral feature images to drive an automated spline based non-linear image registration procedure. Multimodal image registration is significantly more complicated than registration of images from the same modality or protocol on account of difficulty in quantifying similarity between different structural and functional information, and also due to possible physical deformations resulting from the data acquisition process. The COFEMI technique for feature ensemble selection and combination has been previously demonstrated to improve rigid registration performance over intensity-based MI for images of dissimilar modalities with visible intensity artifacts. Hence, we present here the natural extension of feature ensembles for driving automated non-rigid image registration in our new technique termed Collection of Image-derived Non-linear Attributes for Registration Using Splines (COLLINARUS). Qualitative and quantitative evaluation of the COLLINARUS scheme is performed on several sets of real multimodal prostate images and synthetic multiprotocol brain images. Multimodal (histology and MRI) prostate image registration is performed for 6 clinical data sets comprising a total of 21 groups of in vivo structural (T2-w) MRI, functional dynamic contrast enhanced (DCE) MRI, and ex vivo WMH images with cancer present. Our method determines a non-linear transformation to align WMH with the high resolution in vivo T2-w MRI, followed by mapping of the histopathologic cancer extent onto the T2-w MRI. The cancer extent is then mapped from T2-w MRI onto DCE-MRI using the combined non-rigid and affine transformations determined by the registration. Evaluation of prostate registration is performed by comparison with the 3 time point (3TP) representation of functional DCE data, which provides an independent estimate of cancer extent. The set of synthetic multiprotocol images, acquired from the BrainWeb Simulated Brain Database, comprises 11 pairs of T1-w and proton density (PD) MRI of the brain. Following the application of a known warping to misalign the images, non-rigid registration was then performed to recover the original, correct alignment of each image pair. Quantitative evaluation of brain registration was performed by direct comparison of (1) the recovered deformation field to the applied field and (2) the original undeformed and recovered PD MRI. For each of the data sets, COLLINARUS is compared with the MI-driven counterpart of the B-spline technique. In each of the quantitative experiments, registration accuracy was found to be significantly (p < 0.05) for COLLINARUS compared with MI-driven B-spline registration. Over 11 slices, the mean absolute error in the deformation field recovered by COLLINARUS was found to be 0.8830 mm.

Chappelow, Jonathan; Bloch, B. Nicolas; Rofsky, Neil; Genega, Elizabeth; Lenkinski, Robert; DeWolf, William; Viswanath, Satish; Madabhushi, Anant

2009-02-01

59

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)

60

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

61

Doppler indicates of uterine artery Doppler velocimetry by placental location  

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-09-15

62

[Doppler echocardiography in mitral insufficiency].  

Science.gov (United States)

The Doppler method (pulsatile and continuous) was used for finding out and semiquantitatively evaluating the mitral insufficiency of various etiologies: inflammatory (rheumatic); prolapse of mitral valve; obstructive hypertrophic cardiomyopathy; dilatative cardiomyopathy; calcification of valvular ring. The Doppler parameters obtained after automatic processing of the image (speed transvalvular pressure gradient, flow period and acceleration) offer data on the diastolic performance of the left ventricle. Registration of the aortic flow makes possible the calculation of the cardiac flow (the diameter of the aorta is measured in echo-B), and of the aortic flow permits the noninvasive evaluation of the lung arterial pressure. The method offers a large vista in the noninvasive evaluation of the patients suffering from mitral insufficiency. PMID:1978395

Streian, C; Dr?gulescu, S I; Brânzan, L; Streian, C G; Turcan, M

1990-01-01

63

Compact laser Doppler choroidal flowmeter  

Science.gov (United States)

A compact instrument is described that allows the measurement of the laser Doppler flow parameters, i.e., the velocity, the volume, and flow of blood in the foveal region of the human choroidal vascular system. This new device uses the optical principle of confocality for the delivery of the laser light to the site of measurement and heterodyne detection of the Doppler frequency shifted scattered light. Power of the incident light (785 nm) at the cornea is 90 (mu) W. Measurements were obtained in both eyes of a group of 21 normal volunteers without pupil dilatation. We determined the intrasubject reproducibility and the minimum statistically significant detectable changes in the flow parameters for a group of 21 eyes (one in each subject). Linear correlations were also established between the flow parameters in the right and left eyes.

Geiser, Martial H.; Diermann, Ulrich; Riva, Charles E.

1999-10-01

64

Doppler peaks from active perturbations  

OpenAIRE

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. ...

Magueijo, J.; Albrecht, A.; Coulson, D.; Ferreira, P.

1995-01-01

65

Measurement of the Doppler power of flowing blood using ultrasound Doppler devices.  

Science.gov (United States)

Measurement of the Doppler power of signals backscattered from flowing blood (henceforth referred to as the Doppler power of flowing blood) and the echogenicity of flowing blood have been used widely to assess the degree of red blood cell (RBC) aggregation for more than 20 y. Many studies have used Doppler flowmeters based on an analogue circuit design to obtain the Doppler shifts in the signals backscattered from flowing blood; however, some recent studies have mentioned that the analogue Doppler flowmeter exhibits a frequency-response problem whereby the backscattered energy is lost at higher Doppler shift frequencies. Therefore, the measured Doppler power of flowing blood and evaluations of RBC aggregation obtained using an analogue Doppler device may be inaccurate. To overcome this problem, the present study implemented a field-programmable gate array-based digital pulsed-wave Doppler flowmeter to measure the Doppler power of flowing blood, in the aim of providing more accurate assessments of RBC aggregation. A clinical duplex ultrasound imaging system that can acquire pulsed-wave Doppler spectrograms is now available, but its usefulness for estimating the ultrasound scattering properties of blood is still in doubt. Therefore, the echogenicity and Doppler power of flowing blood under the same flow conditions were measured using a laboratory pulser-receiver system and a clinical ultrasound system, respectively, for comparisons. The experiments were carried out using porcine blood under steady laminar flow with both RBC suspensions and whole blood. The experimental results indicated that a clinical ultrasound system used to measure the Doppler spectrograms is not suitable for quantifying Doppler power. However, the Doppler power measured using a digital Doppler flowmeter can reveal the relationship between backscattering signals and the properties of blood cells because the effects of frequency response are eliminated. The measurements of the Doppler power and echogenicity of flowing blood were compared with those obtained in several previous studies. PMID:25542489

Huang, Chih-Chung; Chou, Hung-Lung; Chen, Pay-Yu

2015-02-01

66

General principles of carotid Doppler ultrasonography  

Directory of Open Access Journals (Sweden)

Full Text Available

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

Whal Lee

2014-01-01

67

Generic Doppler processor speeds radar analysis  

Science.gov (United States)

The design and operation of a generic Doppler processor (GDP) are described in detail and illustrated with diagrams. The GDP was developed to facilitate the selection of a Doppler processing method for a radar system; it operates on an industrial desktop computer and makes it possible to switch rapidly among different Doppler processing bandwidths and center frequencies, filtering methods (FFT, analog, etc.), windowing methods, numbers of bits for quantization, and output display formats. The principal components are a programmable baseband clutter filter module, a Doppler processor chassis, a synthetic range-Doppler display, and a spectrum-analyzer-type real-Doppler display. The GDP provides + or - 5O kHz coverage with filter bandwidth 200 Hz, a maximum of 512 channels, 10 range gates, and an instantaneous dynamic range of 60 dB. Also discussed is the efficient finite-impulse-response filter design used to simulate analog filter banks.

Engler, Harold F., Jr.; West, Philip D.; Austin, Mark D.; Gardos, Thomas R.

1991-03-01

68

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

69

Chromospheric Doppler Velocity Oscillations in a Sunspot  

OpenAIRE

We analyse the chromospheric Doppler velocity oscillations in a sunspot using the high resolution spectral observations obtained from the Fast Imaging Solar Spectrograph(FISS) of the New Solar Telescope at the Big Bear Solar Observatory. The Doppler velocity maps are constructed from the bisectors of the spectral observations. The time series analysis of Doppler velocity maps show enhanced power in the sunspot umbra at higher frequencies and in the penumbra at lower frequenc...

Maurya, R. A.

2013-01-01

70

Speckles in laser Doppler perfusion imaging  

OpenAIRE

Laser Doppler Flowmetry (LDF) is a noninvasive diagnostic method to measure blood flow in tissue [1]. The technique is based on measuring the Doppler shift induced by moving red blood cells to the illuminating coherent light. A laser Doppler instrument often gives output signals related to the flux, velocity and concentration of the moving blood cells. These parameters are extracted from the power spectrum of the intensity fluctuations produced by a photodetector. There are two types of perfu...

Rajan, Vinayakrishnan

2006-01-01

71

Postoperative doppler evaluation of liver transplants  

OpenAIRE

Doppler ultrasound plays an important role in the postoperative management of hepatic transplantation, by enabling early detection and treatment of various vascular complications. This article describes the normal Doppler findings following liver transplantation and reviews the imaging appearances of various vascular complications associated with it. The article also discusses transient waveform abnormalities, often seen on a post-transplant Doppler examination, and the importance of differen...

Sanyal, Rupan; Zarzour, Jessica G.; Ganeshan, Dakshina M.; Bhargava, Puneet; Lall, Chandana G.; Little, Mark D.

2014-01-01

72

Postoperative doppler evaluation of liver transplants.  

Science.gov (United States)

Doppler ultrasound plays an important role in the postoperative management of hepatic transplantation, by enabling early detection and treatment of various vascular complications. This article describes the normal Doppler findings following liver transplantation and reviews the imaging appearances of various vascular complications associated with it. The article also discusses transient waveform abnormalities, often seen on a post-transplant Doppler examination, and the importance of differentiating them from findings suggestive of ominous vascular complications. PMID:25489129

Sanyal, Rupan; Zarzour, Jessica G; Ganeshan, Dakshina M; Bhargava, Puneet; Lall, Chandana G; Little, Mark D

2014-10-01

73

Avaliação dos tumores hepáticos ao Doppler Doppler evaluation of liver tumors  

OpenAIRE

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 ...

Márcio Martins Machado; Ana Cláudia Ferreira Rosa; Paulo Herman; Nestor de Barros; Orlando Milhomem da Mota; Letícia Martins Azeredo; Osterno Queiroz da Silva; Jales Benevides Santana Filho; Campoli, Paulo Moacir O.; Barreto, Paulo Adriano Q.; Patrícia Medeiros Milhomem; Leonardo Medeiros Milhomem; Murilo Tavares Daher; Renato Tavares Daher; Luciana Mendes de Oliveira Cerri

2004-01-01

74

Dark resonances with variable Doppler sensitivity  

International Nuclear Information System (INIS)

We have studied dark resonances in a thermal gas of rubidium atoms using a variable angle between the two driving optical beams. The inclined angle was tuned between a Doppler-free situation (i.e., collinear beams) and near 10-3 rad, yielding an effective Doppler sensitivity of a far-infrared photon. For the case of buffer gas cells, Dicke narrowing occurs. We can carefully control the transition between the Dicke regime, in which the Doppler broadening is suppressed, and the Doppler-broadened regime, in which the thermal atomic motion strongly couples to the three-level atoms

75

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Science.gov (United States)

...SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging...pulsed doppler imaging system is a device that combines the features of continuous wave doppler-effect technology...

2010-04-01

76

Airborne Differential Doppler Weather Radar  

Science.gov (United States)

The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the differential reflectivity and Doppler as functions of the center frequency, frequency difference, and median mass diameter. For a fixed pair of frequencies, the detectability of the differential signals can be expressed as the number of independent samples required to detect rain or snow with a particular median mass diameter. Because sampling numbers on the order of 1000 are needed to detect the differential signal over a range of size distributions, the instrument must be confined to a near-nadir, narrow swath. Radar measurements from a zenith directed radar operated at 9.1 GHz and 10 GHz are used to investigate the qualitative characteristics of the differential signals. Disdrometer and rain gauge data taken at the surface, just below the radar, are used to test whether the differential signals can be used to estimate characteristics of the raindrop size distribution.

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

2001-01-01

77

Doppler tomography in fusion plasmas and astrophysics  

DEFF Research Database (Denmark)

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

Salewski, Mirko; Geiger, B.

2015-01-01

78

CW doppler examination of breast masses  

International Nuclear Information System (INIS)

Real-time US examinations and 10-MHzCW Doppler examinations of the breast were performed in 173 women referred for either a palpable breast lesion or abnormal findings on mammography. Pathologic correlation was obtained in 85 cases. Abnormal Doppler signals are characterized by high velocity, low impedance, and a systolic peak frequency exceeding that of the contralateral side by 2 kHz. In the authors' series, Doppler examinations produced a sensitivity of 66% and a specificity of 73% for the diagnosis of breast cancer. Doppler examination is less sensitive for detecting malignancy in the presence of bilateral disease. Doppler signals in patients with juvenile fibroadenomas can be indistinguishable from malignant signals

79

Doppler Resilient Waveforms with Perfect Autocorrelation  

CERN Document Server

We describe a method of constructing a sequence of phase coded waveforms with perfect autocorrelation in the presence of Doppler shift. The constituent waveforms are Golay complementary pairs which have perfect autocorrelation at zero Doppler but are sensitive to nonzero Doppler shifts. We extend this construction to multiple dimensions, in particular to radar polarimetry, where the two dimensions are realized by orthogonal polarizations. Here we determine a sequence of two-by-two Alamouti matrices where the entries involve Golay pairs and for which the sum of the matrix-valued ambiguity functions vanish at small Doppler shifts. The Prouhet-Thue-Morse sequence plays a key role in the construction of Doppler resilient sequences of Golay pairs.

Pezeshki, A; Moran, W; Howard, S D; Pezeshki, Ali; Moran, William; Howard, Stephen D.

2007-01-01

80

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%) shohowed 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

81

Doppler transcraniano na prática neurológica  

Directory of Open Access Journals (Sweden)

Full Text Available O Doppler transcraniano (DTC é um método relativamente novo, descrito em 1982 por Rune Aaslid e introduzido no Brasil em 1992 por Roberto Hirsch, na Universidade de São Paulo. O serviço de Neurologia do Hospital de Clínicas da Universidade Federal do Paraná (HC-UFPR disponibilizou esse exame em 2001, com divulgação das principais vantagens do método no diagnóstico, seguimento e manejo terapêutico de pacientes com suspeita ou portadores de doença cerebrovascular. O objetivo deste trabalho é demonstrar como o DTC vem sendo utilizado em nosso meio e quais são as especialidades médicas que vêm absorvendo o auxílio do método. Embora diretrizes como a publicada pela Academia Americana de Neurologia em 2004 validem as indicações do DTC, estabelecendo especificidade e sensibilidade do método, verificamos que a solicitação do exame em nosso meio depende da divulgação do serviço, da implementação de linhas de pesquisa e, finalmente, do reconhecimento de sua utilidade na prática diária.

Zétola Viviane Flumignan

2006-01-01

82

Patient-exposure data for doppler ultrasound  

International Nuclear Information System (INIS)

In recent years ultrasound imaging and Doppler blood flow measurements have become important tools for use in diagnostic medicine. Commercial pulse-echo imaging equipment was first introduced into commerce in 1963. The first commercial continuous wave Doppler unit was introduced to the marketplace in 1966. As equipment improved and applications developed, the industry experienced rapid growth in the 1970s. One of the more recent growth areas in the application of diagnostic ultrasound has been the use of pulsed Doppler equipment for cardiac applications. Prior to 1976, some continuous wave Doppler ultrasound was used for cardiovascular diagnosis. However, only a single manufacturer marketed a pulsed Doppler clinical instrument for cardiac or peripheral vascular diagnosis. Currently, many continuous wave and pulsed Doppler instruments are commercially available for both peripheral vascular and cardiac diagnosis. This chapter (1) briefly reviews current safety guidelines, regulations, and recommendations for diagnostic ultrasound; (2) discusses the patient-exposure intensities associated with Doppler ultrasound medical equipment and compare these levels of exposure with intensities from other medical ultrasound devices; and (3) considers some of the current information as it relates to the safety of diagnostic ultrasound

83

Chromospheric Doppler Velocity Oscillations in a Sunspot  

CERN Document Server

We analyse the chromospheric Doppler velocity oscillations in a sunspot using the high resolution spectral observations obtained from the Fast Imaging Solar Spectrograph(FISS) of the New Solar Telescope at the Big Bear Solar Observatory. The Doppler velocity maps are constructed from the bisectors of the spectral observations. The time series analysis of Doppler velocity maps show enhanced power in the sunspot umbra at higher frequencies and in the penumbra at lower frequencies. We find that the peak power frequency decreases gradually from the umbra to outward.

Maurya, R A

2013-01-01

84

Preliminary simulation study of doppler reflectometry  

International Nuclear Information System (INIS)

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

85

Doppler shift effect on infrared band models  

International Nuclear Information System (INIS)

This paper reviews the treatment of Doppler shifts on a Voigt profile spectral line and then generalizes this result to the curve of growth (i.e., equivalent width) for both a single line and an infrared band model. A synthetic spectrum for the CO2 4.3-micron band is computed with and without Doppler shifts to illustrate the magnitude of the effect. It is found that band model computations are unaffected by Doppler shift in the limiting cases of small and large absorber amount. In the case of intermediate absorber amounts, however, significant effects are predicted for hypersonic flows. 15 refs

86

Doppler sonography of the native liver  

International Nuclear Information System (INIS)

Doppler sonography is being used routinely in evaluating the vascular structures of the native liver because of its ease of use, lower cost, easier availability, lack of need for X-ray and accuracy. Doppler sonography can well demonstrate the vascularization of liver tumors, portal vein thrombosis, portal vein abnormalities in patients with portal hypertension and hepatic venous findings in patients with Budd-Chiari syndrome. The purpose of this article is to present information about Doppler sonography of the native liver and to show its usefulness in the evaluation of hepatic vascular diseases

87

Carotid Artery Doppler Assessment In Patients Accussed Of Strokes  

OpenAIRE

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 ...

Mazaher, H.; Sharif Kashani, S.

2005-01-01

88

IIP Update: A Packaged Coherent Doppler Wind Lidar Transceiver. Doppler Aerosol WiNd Lidar (DAWN)  

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.; Koch, Grady J.; Yu, Jirong; Trieu, Bo C.; Amzajerdian, Farzin; Singh, Upendra N.; Petros, Mulugeta

2006-01-01

89

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

90

Generalized Doppler Formula in a Nonstatic Universe  

Science.gov (United States)

Derives the general Doppler formula in a nonstatic universe using assumptions of special relativity, homogeneity and isotropy of the universe. Examples of applications to physical cosmology are given. (SL)

Gross, Peter G.

1977-01-01

91

Laser Doppler flowmetry in microvascular surgery  

OpenAIRE

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

Adrichem, L. N. A.

1992-01-01

92

Microwave Doppler reflectometer system in LHD.  

Science.gov (United States)

In order to measure the poloidal rotation velocity, a Doppler reflectometer has been developed in Large Helical Device (LHD). A remotely controlled antenna tilting system has been installed in an LHD vacuum vessel. A synthesizer is used as the source, and the operation microwave frequency ranges are ka-band and V-band. In LHD last experimental campaign we obtained the Doppler shifted signal, which was consistent with CXRS measurements. PMID:23126980

Tokuzawa, T; Ejiri, A; Kawahata, K; Tanaka, K; Yamada, I; Yoshinuma, M; Ida, K; Suzuki, C

2012-10-01

93

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

94

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

95

Borescopic Laser Doppler Velocimetry probe  

Science.gov (United States)

A miniature fiber-optic, single-velocity-component Laser Doppler Velocimetry (LDV) probe for measurement in cramped spaces, where access is very limited, has been designed, constructed, and tested. The probe design allows the main probe dimensions to be small (7mm in diameter). In addition, the proposed back-scatter collection scheme allows the main section to be as long as needed to access remote locations. The laser beams are first collimated by passing them through two separate collimating lenses. The collimated light then passes through 1 mm holes machined into a right angle prism-mirror and are focused to form the measurement probe volume using the focusing lens placed at the end of the probe extension tube. The light scattered by the particles in the flow is collected back by the focusing lens and is collimated. The collimated light then reflects off the right-angle mirror by 90 degrees, passes through the receiving lens, and is focused to the receiving fiber terminator. The receiving fiber-optic cable transmits the collected light to the photo-multiplier tube which then converts the signal into an electrical signal for further processing of the data. The probe working principle was proven in two types of jet flows.

O'Brien, Kory T.

96

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

97

Doppler Signatures In EVE Spectra  

Science.gov (United States)

The Extreme-ultraviolet Variability Experiment (EVE) on SDO is providing a comprehensive set of EUV spectra of the Sun as a star. The routine sampling is with 10 s integrations at a resolution of 0.1 nm. Although this resolution corresponds to only some 1000 km/s in velocity space, we demonstrate that the instrument is stable enough to detect the SDO orbital motion of a few km/s readily in the bright He II line at 30.4 nm. We find the random error in the centroid location of this line to be less than one pm (less than 1 km/s) per 10 s integration. We also note systematic effects from a variety of causes. For flare observations, the line centroid position depends on the flare position. We discuss the calibration of this effect and show that EVE can nonetheless provide clear Doppler signatures that may be interpreted in terms of flare dynamics. This information has some value in and of itself, because of EVE's sensitivity, but we feel that it will be of greatest importance when combined with imagery (e.g., via AIA) a modeling. We discuss flare signatures in several events, e.g. the gamma-ray flare SOL2010-06-12 and SOL2011-02-16T:07:44, taking advantage of AIA image comparisons.

Hudson, Hugh S.; Chamberlin, P.; Woods, T.; Fletcher, L.; Graham, D.

2011-05-01

98

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

99

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 [18F]-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.

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

2012-12-01

100

Avaliação dos tumores hepáticos ao Doppler / Doppler evaluation of liver tumors  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 auxi [...] liar 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. Abstract in english 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 identificat [...] ion 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; Ana Cláudia Ferreira, Rosa; Paulo, Herman; Nestor de, Barros; Orlando Milhomem da, Mota; Letícia Martins, Azeredo; Osterno Queiroz da, Silva; Jales Benevides, Santana Filho; Paulo Moacir O., Campoli; Paulo Adriano Q., Barreto; Patrícia Medeiros, Milhomem; Leonardo Medeiros, Milhomem; Murilo Tavares, Daher; Renato Tavares, Daher; Luciana Mendes de Oliveira, Cerri; William Abrão, Saad; Giovanni Guido, Cerri.

2004-10-01

101

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 fs, 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

102

Doppler-corrected differential detection of MPSK  

Science.gov (United States)

An open-loop technique is presented for estimating and correcting Doppler frequency shift in an M-ary differential phase-shift-keyed (MDPSK) receiver. The novelty of the scheme is based on the observation that whereas the change in phase of the received signal over a full symbol contains the sum of the data (phase) and the Doppler-induced phase shift, the same change in phase over half a symbol (within a given symbol interval) contains only the Doppler-induced phase shift. Thus, by proper processing, the latter can be estimated and removed from the former. Analytical and simulation results are given for the variance of the above estimator, and the error probability performance of the MDPSK receiver is evaluated in the presence of the Doppler correction. Next, the practical considerations associated with the application of this technique on bandlimited Nyquist channels are discussed and incorporated into the final design. It is shown that the receiver can, in the absence of timing jitter, be designed to allow combined Doppler correction and data detection with no penalty due to intersymbol interference (ISI). The effects of ISI due to timing jitter are assessed by computer simulation.

Simon, Marvin K.; Divsalar, Dariush

1989-01-01

103

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

104

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

105

Doppler radar imaging of spherical planetary surfaces  

International Nuclear Information System (INIS)

A new approach to making radar reflectivity images of spherical planetary objects uses echo spectra acquired as a function of rotational phase and at an arbitrary number of subradar latitudes. If only equatorial views are used then the image will have a north-south ambiguity. If non-equatorial views are used than unambiguous images are possible. The technique is tailored for depolarized or diffuse (nonspecular) polarized backscatter and works best when the limb darkening is minimal. In developing the Doppler-radar imaging system, the target's reflectivity distribution is expanded in a truncated spherical harmonic series and the distribution of echo power in rotational phase and Doppler frequency is obtained as a linear, analytic function of the series coefficients. To estimate the coefficients from an observed phase-Doppler distribution, the inversion is cast as a least-squares problem and solved using singular value decomposition. The result is a linear imaging system whose capabilities and sensitivity to such factors as subradar latitude coverage and signal-to-noise ratio are easily explored with simulations. Doppler-radar imaging can be used with existing radar telescopes to map the diffuse component of echoes from the inner planets and to make north-south ambiguous reflectivity maps of the icy Galilean satellites. SNRs needed for Doppler-radar imaging of the largest asteroids, Io, and Titan would be accessible upon implementation of upgrades proposed for the Arecintation of upgrades proposed for the Arecibo telescope

106

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

107

Diabetic Nephropathy : Evaluation with Doppler Ultrasonography  

International Nuclear Information System (INIS)

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

108

Arm locking with Doppler estimation errors  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2010-05-01

109

Doppler flow patterns in pediatric pulmonary pathology  

International Nuclear Information System (INIS)

To differentiate, in a number of pediatric lung diseases, a series of Doppler flow patterns according to their pulmonary or systemic origin, assessing the morphology of the spectral curve. We have reviewed the Doppler studies carried out in 22 patients with a variety of pulmonary pathologies, including several pulmonary abnormalities: three cases of sequestration, four cases of pulmonary vein drainage problems (one with no evidence of associated pulmonary abnormality, two with scimitar syndrome and one variant with accessory diaphragm), one case of cystic adenomatoid malformation, three cases of metastatic neoplastic lesion, one case of hydatid cyst and 10 cases of infections pathology and atelectasis, the underlying causes of which were unknown. We have found four basis patterns of pulmonary or systemic arterial and venous vascularization in ultrasonographic studies. We conclude that the use of Doppler ultrasound associated with standard ultrasonography is a very helpful tool in the initial diagnosis of pulmonary vascularization abnormalities. (Author)

110

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

OpenAIRE

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...

Luca Giugno; Francesca Zanier; Marco Luise

2007-01-01

111

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

International Nuclear Information System (INIS)

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

112

Velocity measurement by vibro-acoustic Doppler.  

Science.gov (United States)

We describe the theoretical principles of a new Doppler method, which uses the acoustic response of a moving object to a highly localized dynamic radiation force of the ultrasound field to calculate the velocity of the moving object according to Doppler frequency shift. This method, named vibro-acoustic Doppler (VAD), employs two ultrasound beams separated by a slight frequency difference, ?f, transmitting in an X-focal configuration. Both ultrasound beams experience a frequency shift because of the moving objects and their interaction at the joint focal zone produces an acoustic frequency shift occurring around the low-frequency (?f) acoustic emission signal. The acoustic emission field resulting from the vibration of the moving object is detected and used to calculate its velocity. We report the formula that describes the relation between Doppler frequency shift of the emitted acoustic field and the velocity of the moving object. To verify the theory, we used a string phantom. We also tested our method by measuring fluid velocity in a tube. The results show that the error calculated for both string and fluid velocities is less than 9.1%. Our theory shows that in the worst case, the error is 0.54% for a 25° angle variation for the VAD method compared with an error of -82.6% for a 25° angle variation for a conventional continuous wave Doppler method. An advantage of this method is that, unlike conventional Doppler, it is not sensitive to angles between the ultrasound beams and direction of motion. PMID:22547286

Nabavizadeh, Alireza; Urban, Matthew W; Kinnick, Randall R; Fatemi, Mostafa

2012-04-01

113

Rotational Doppler beaming in eclipsing binaries  

CERN Document Server

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 analogue 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.

Groot, Paul J

2011-01-01

114

Fish embryo multimodal imaging by laser Doppler digital holography  

CERN Document Server

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

Verrier, Nicolas; Picart, Pascal; Gross, Michel

2015-01-01

115

Spectral Doppler of the Hepatic Veins in Tricuspid Valve Disease.  

Science.gov (United States)

Spectral Doppler recording of the hepatic veins (HV) provides a semiquantitative assessment of tricuspid regurgitation (TR) severity. It complements findings on two-dimensional echocardiography and color Doppler imaging and helps to discriminate between hemodynamically significant and nonsignificant degree of regurgitation. In this manuscript, we discuss the usefulness of the HV Doppler for the diagnosis of tricuspid valve (TV) disease and provide examples of the various spectral Doppler patterns that assist in the quantification of TR. PMID:25250676

Fadel, Bahaa M; Almulla, Khaled; Husain, Aysha; Dahdouh, Ziad; Di Salvo, Giovanni; Mohty, Dania

2014-09-23

116

Ionospheric Doppler measurements by means of HF-radar techniques  

OpenAIRE

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. ...

Altadill, D.; Bianchi, C.

2005-01-01

117

Laser radar range profile, Doppler spectra and range resolved Doppler imaging technologies for the target recognition  

Science.gov (United States)

The development of laser range profile, Doppler spectra and Range Resolved Doppler imaging technologies including the experiments, simulations and engineering applications have been summarized and reviewed in this paper. It was analyzed the problems of the laser radar imaging system which need to solve in experiments and models. The achievements and the key technologies of Range profile, Doppler spectra and Range Doppler imaging laser radar are reported in detail. Different typically theoretical simulated models have been built to show the last technologies of target recognition for laser radar in order to be based on the further studying on designing the laser radar imaging systems in many applications and offering the precise data of the detected target.

Wu, Pengfei; Wang, Ming-Jun; Ke, Xi-zheng; Gong, Yan-jun; Teng, Yang

2014-11-01

118

Hereditary haemorrhagic teleangiectasia: hepatic lesions demonstrated with colour Doppler and power Doppler sonography  

International Nuclear Information System (INIS)

Visceral vascular abnormalities in patients with hereditary haemorrhagic teleangiectasia (HHT) include teleangiectasis, arteriovenous fistula (AVF), and aneurysms. Sonographic findings and colour Doppler ultrasound (CDU) features of HHT in the liver have been described in a few reports. Presented here is the CDU finding of liver with HHT involvement in two patients, aged 52 and 29 years, respectively. Power Doppler sonography was also performed in the first patient in whom both CDU and power Doppler sonography could demonstrate the abnormal vascular channels in the liver. In the second patient, aneurysms in the left hepatic lobe and of the splenic artery were noted. Angiography was performed in both patients and confirmed the abnormal vascular lesions demonstrated by CDU and/or power Doppler sonographic findings

119

Transcranial Doppler ultrasonography: year 2000 update.  

Science.gov (United States)

In this update, the main clinical applications of transcranial Doppler ultrasonography are reassessed. A specific format for technology assessment, personal experience, and an extensive review of the literature form the basis of the evaluation. The document is approved by the American Society of Neuroimaging and the Neurosonology Research Group of the World Federation of Neurology. PMID:10800264

Babikian, V L; Feldmann, E; Wechsler, L R; Newell, D W; Gomez, C R; Bogdahn, U; Caplan, L R; Spencer, M P; Tegeler, C; Ringelstein, E B; Alexandrov, A V

2000-04-01

120

Measurements of the Doppler effect at Phenix  

International Nuclear Information System (INIS)

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

121

Aerosol distribution measurements by laser - Doppler - spectroscopy  

International Nuclear Information System (INIS)

Laser-Doppler-Spectroscopy is used to study particle size distribution, especially sodium aerosols, in the presence of uncondensable gases. Theoretical basis are given, and an experimental technique is described. First theoretical results show reasonably good agreement with experimental data available; this method seems to be a promising one. (author)

122

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

OpenAIRE

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 va...

Shahriaran, S.; Ahmadi Nejad, P.; Ghasemi Phiroozabadi, A.; Giti, M.

2002-01-01

123

Assessment of coronary flow reserve with transthoracic Doppler echocardiography: comparison with intracoronary Doppler method.  

OpenAIRE

To evaluate the feasibility and usefulness of transthoracic Doppler echocardiography (TTDE) as a non-invasive method in recording distal anterior descending (LAD) coronary flow velocity, we compared coronary flow reserve (CFR) measured by TTDE with measurements by intracoronary Doppler wire (ICDW). Twenty-one patients without LAD stenosis were studied. ICDW performed at baseline and after intracoronary injection of 18 microg adenosine. TTDE was performed at baseline and after intravenous aden...

Kim, S. M.; Shim, W. J.; Lim, H. E.; Hwang, G. S.; Song, W. H.; Lim, D. S.; Kim, Y. H.; Seo, H. S.; Oh, D. J.; Ro, Y. M.

2000-01-01

124

A Magnetic Calibration of Photospheric Doppler Velocities  

Science.gov (United States)

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-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° ambiguity.

Welsch, Brian T.; Fisher, George H.; Sun, Xudong

2013-03-01

125

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

126

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

127

Minior Actinide Doppler Coefficient Measurement Assessment  

Energy Technology Data Exchange (ETDEWEB)

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

Nolan E. Hertel; Dwayne Blaylock

2008-04-10

128

Color Doppler US of the penis  

International Nuclear Information System (INIS)

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

129

Brain Embolism Monitoring with Transcranial Doppler Ultrasound.  

Science.gov (United States)

Embolism is considered to be the main mechanism leading to brain infarction today; with the introduction of sophisticated neuroimaging tools, its impact is increasingly appreciated. Transcranial Doppler ultrasound allows noninvasive monitoring of in vivo embolism. Acute stroke, internal carotid artery stenosis, several cardiac conditions, internal carotid endarterectomy, and coronary artery bypass graft surgery have been extensively monitored. These investigations and other clinical and neuroimaging studies have expanded the understanding of brain embolism; they suggest it may be appropriate to think of it as a process that occurs in the context of other hemodynamic factors. Differences have been identified among several conditions regarding the temporal profile of embolism and the characteristics of embolic particles. This article presents a brief review of brain embolism monitoring with transcranial Doppler ultrasound. PMID:12777200

Babikian, Viken L.; Wijman, Christine A.

2003-07-01

130

Design of a Doppler reflectometer for KSTAR  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-11-15

131

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

132

Color Doppler US of the penis  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-07-01

133

A Magnetic Calibration of Photospheric Doppler Velocities  

CERN Document Server

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

134

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.

135

Rotational Doppler Beaming in Eclipsing Binaries  

Science.gov (United States)

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.

Groot, Paul J.

2012-01-01

136

Positive power Doppler signal in plantar fasciitis.  

Science.gov (United States)

The plantar fascia is a multilayered band of fibrous tissue that support and maintain the longitudinal arch of the foot. We report a 34-old obese woman with heel pain for the past 3 years. On physical examination, she presented painful plantar fascia throughout extension of the foot. In addition, a soft painful, mobile nodule was also palpated in the medial aspect of her left heel. An US examination of her left foot showed an increased thickness of her plantar fascia with reduced echogenity, the presence of an effusion and a positive power Doppler signal. Positive US Doppler signal may be helpful in evaluating patients with plantar fasciitis and is suggestive of the presence of active microcirculation. PMID:22065073

Mendonça, José Alexandre; Provenza, José Roberto; Appenzeller, Simone

2013-02-01

137

Renal duplex Doppler ultrasound findings in diabetics  

International Nuclear Information System (INIS)

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

138

Transcranial Doppler sonography in familial hemiplegic migraine  

Energy Technology Data Exchange (ETDEWEB)

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

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

1991-02-01

139

Spatial and Wavenumber Resolution of Doppler Reflectometry  

CERN Document Server

Doppler reflectometry spatial and wavenumber resolution is analyzed within the framework of the linear Born approximation in slab plasma model. Explicit expression for its signal backscattering spectrum is obtained in terms of wavenumber and frequency spectra of turbulence which is assumed to be radially statistically inhomogeneous. Scattering efficiency for both back and forward scattering (in radial direction) is introduced and shown to be inverse proportional to the square of radial wavenumber of the probing wave at the fluctuation location thus making the spatial resolution of diagnostics sensitive to density profile. It is shown that in case of forward scattering additional localization can be provided by the antenna diagram. It is demonstrated that in case of backscattering the spatial resolution can be better if the turbulence spectrum at high radial wavenumbers is suppressed. The improvement of Doppler reflectometry data localization by probing beam focusing onto the cut-off is proposed and described....

Surkov, A; Surkov, Alexander; Gusakov, Evgeniy

2004-01-01

140

Global textures and the Doppler peaks  

OpenAIRE

We review recent work aimed at showing how global topological defects influence the shape of the angular power spectrum of the CMB radiation on small scales. While Sachs-Wolfe fluctuations give the dominant contribution on angular scales larger than about a few degrees, on intermediate scales the main r\\^ole is played by coherent oscillations in the baryon radiation plasma before recombination. In standard cosmological models these oscillations lead to the `Doppler peaks' in...

Gangui, Alejandro; Durrer, Ruth; Sakellariadou, Mairi

1996-01-01

141

Colour Doppler ultrasound of the penis  

International Nuclear Information System (INIS)

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

142

Colour Doppler ultrasound of the penis  

Energy Technology Data Exchange (ETDEWEB)

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

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

2003-07-01

143

Doppler study of cerebral arteries in hypercholesterolemia  

OpenAIRE

Mehdi Farhoudi1, Kaveh Mehrvar2, Naser Aslanabadi3, Kamyar Ghabili1, Nazila Rasi Baghmishe4, Farzad Ilkhchoei41Neuroscience Research Center, 2Razi Hospital, 3Department of Cardiology, 4Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, IranBackground: Hypercholesterolemia is one of the major modifiable risk factors for atherosclerosis of the coronary and carotid arteries. Although transcranial Doppler (TCD) studies of the cerebral arteries are indicative of decreased cerebral...

Farhoudi M; Mehrvar K; Aslanabadi N; Ghabili K; Nr, Baghmishe; Ilkhchoei F

2011-01-01

144

Doppler Findings in Intrapartum Fetal Distress  

OpenAIRE

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

Khatereh Tooba; Laleh Eslamian

2011-01-01

145

The Doppler Peaks from Cosmic Texture  

OpenAIRE

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

146

Sub-Nyquist Radar via Doppler Focusing  

OpenAIRE

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

147

The observability of secondary doppler peaks  

OpenAIRE

By proposing a statistic for the detection of secondary (Doppler) peaks in the CMBR power spectrum, the significance level at which such peaks may be detected are computed for a large range of model CMBR experiments. In particular, we investigate experimental design features required to distinguish between competing cosmological theories, such as cosmic strings and inflation, by establishing whether or not secondary peaks are present in the CMBR power spectrum.

Hobson, Michael P.

1996-01-01

148

Some notes on the relativistic Doppler effect  

International Nuclear Information System (INIS)

The properties of the analytical formula of the relativistic Doppler-effect are discussed from the geometric standpoint. It is shown, in particular, that, contrary to the widely accepted view, as the observer and the source of electromagnetic radiation approach one another, in addition to the violet shift also a zero and a red shift (z ? 0) can be observed depending on the angle ? between the vector of relative velocity ? and the observation direction. (methodological notes)

149

Doppler compensated underwater acoustic communication system  

Science.gov (United States)

Spread spectrum methods are used in communication systems to provide a low probability of intercept in hostile environments and multiple access capability in systems shared by many users as well as to provide high processing gain in channels where the transmitted signal is distorted by multipath effects. Such systems serve to be an effective tool for underwater telemetry environments, where multipath propagation effect and Doppler spreading is seen to be more predominant. This paper describes the implementation of a Doppler compensated underwater telemetry system based on CDMA technique. The system consists of multiple CDMA transmitters and a phase locked loop based carrier recoverable CDMA receiver. The effects of the Doppler shift can be compensated by the carrier recovery subsystem in the demodulator, based on PLL technique, which extracts the carrier frequency/phase and simultaneously demodulates the signal. The decision device in the receiver consists of a PN sequence generator as well as a bank of correlators, which are used to determine the data transmitted. The system simulation has been implemented in MATLAB. The advantage of this system is that multiple transmitting stations can transmit simultaneously to a central receiver, thereby increasing the system throughput.

Raj, Anand; George, Binu; Supiya, M. H.; Kurian, James; Pillai, P. R. Saseendran

2001-05-01

150

Doppler flow velocity measurements during coronary angioplasty.  

Science.gov (United States)

In addition to further studies using Doppler catheters to assess blood flow velocity during coronary angioplasty this study intends to evaluate the functional significance of coronary stenoses and to estimate their hemodynamic relevance prior to and after percutaneous transluminal coronary angioplasty (PTCA). Diameters of coronary artery stenoses were quantified by means of the cardiovascular angiographic analysis system (CAAS) both prior to and following successful PTCA in 37 patients. During coronary artery angioplasty a 12 M:Hz 0.018-in. Doppler-tipped guidewire was used to measure prestenotic and poststenotic parameters of coronary artery flow velocity both prior to and following PTCA. The minimal stenosis diameter was raised from 1.01 +/- 0.58 to 1.76 +/- 0.73 mm (P ADPV) peak velocity, systolic (SPVI) and diastolic (DPVI) peak velocity integral, and diastolic/systolic velocity ratio showed--in contrast to further studies--a considerably significant difference (P < 0.05), whereas poststenotic Doppler data (APV, MPV, PVI, ASPV, DSPV, SPVI, DPVI, DSVR) differed highly significantly (P < 0.0001) prior to and following PTCA. Prestenotic and poststenotic measurements of coronary artery flow velocity differed significantly before and after PTCA and offer the potential for estimating both the hemodynamic relevance of coronary artery stenoses and success of PTCA. PMID:7943939

Dill, H; Altstidl, R; Regenfus, M; Lehmkuhl, H; Bachmann, K

1994-10-01

151

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

152

Doppler effect measurement up to 2000 degrees C at FCA  

International Nuclear Information System (INIS)

For the improvement of the Doppler effect calculation accuracy in high temperature range, the measurements of 238U Doppler effect up to 2000 degrees C were carried out as Fast Critical Assembly of JAERI. For the measurements, two methods were used: One is a reactivity worth measurement with a heated sample, and the other is a reaction rate measurement with a heated foil. In analyzing the experimental data, a collision probability cell code with ultra-fine group structure, PEACO-X, was used to generate effective cross sections of the Doppler sample, in which the resonance interaction effects were taken into account. The calculation of the Doppler effect is slightly underestimated the measured Doppler reactivity worths, while it showed a good agreement with the measured Doppler ratios for the reaction rate measurement

153

A 94-GHz Doppler radar for cloud observations  

Science.gov (United States)

A Doppler radar operating at 3.2 mm wavelength was designed and assembled primarily for observation of clouds and precipitation. Phase detection of the radar signals which is required for Doppler operation is implemented through the use of a coherent oscillator phase locked on the transmitter pulse and used as a reference in the phase detector. The radar and associated signal processing techniques such as signal integrator and signal autocovariance estimator are discussed along with the Doppler performance of the radar. Also presented are the results of observation of ice and water clouds and also precipitation, which show the excellent Doppler capabilities of the radar in terms of accuracy of the mean Doppler and Doppler spectrum width.

Lhermitte, Roger

1987-03-01

154

Is tissue Doppler echocardiography the Holy Grail for the intensivist?  

OpenAIRE

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...

Poelaert, Jan; Roosens, Carl

2007-01-01

155

Doppler radar wind field retrieval over the Po Valley  

OpenAIRE

Although methods of using multiple Doppler radars to study wind fields have long been proposed, and many research studies have been made, very few operational radar operators adopt methods which require the use of specific scanning strategies to allow the extraction of wind information. Here we report a collaborative study on dual-Doppler radars based on two Doppler radars in the Po valley, Italy. Unusually, the radars are only about 90 km apart, though operated by the same authority. The win...

Goh, Y. K.; Holt, A. R.; Alberoni, P. P.

2006-01-01

156

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

157

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

158

Spectral Doppler of the hepatic veins in pulmonary hypertension.  

Science.gov (United States)

Pulsed-wave Doppler interrogation of the hepatic veins (HVs) provides a window to right heart hemodynamics and function. Various pathologies that involve the right heart are manifested on the HV Doppler depending on the location and severity of the involvement and its hemodynamic consequences. Pulmonary hypertension (PHTN), a common finding on echocardiographic studies, imparts changes on the HV Doppler that are important to recognize. In this article, we provide a review of the main abnormalities that are encountered on the HV Doppler in patients with PHTN. PMID:25091801

Fadel, Bahaa M; Husain, Aysha; Alassoussi, Nader; Dahdouh, Ziad; Mohty, Dania

2015-01-01

159

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)

160

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

161

Christian Doppler is 200 years young.  

Science.gov (United States)

Christian Doppler was born 200 years ago in Salzburg, Austria, on November 29, 1803, worked in Prague and Vienna and died 150 years ago in Venice. In an article of eight pages he described the principle, which made him famous. It appeared in 1842 with the exotic title: "On the Coloured Light of the Double Stars and Certain Other Stars of the Heaven". The validity of his principle for velocity measurement was confirmed by trumpet sounds produced on a train moving towards and away from the observer. Around 1960 Japanese scientists suggested that flow velocity in blood vessels could be determined by analysing the difference of frequency between emitted and backscattered ultrasound. Rushmer and coworkers built machines suitable for medicine in Seattle, where Eugene Strandness recognized their potential and applied them in first studies. In 1967 the technique jumped to Europe and started to be used worldwide. Already by using continuous wave ultrasound it was possible to diagnose occlusive disease of neck and limb arteries, venous thrombosis and valvular insufficiency with accuracy. Measurements of postestenotic ankle blood pressure were facilitated by Doppler sensing. Over the years more sophisticated instruments were developed. Pulsed emission of ultrasound waves opened a way to study flow velocity profiles across large vessels. By combining the method with A or B mode ultrasound blood flow could be quantified and finally perfused segments of blood vessels visualized. Duplex scanning in its simple and then in its colour coded version is nowadays the standard non-invasive technique that nobody would like to miss. Vascular territories like intracranial, renal and intestinal arteries can also be explored. For the assessment of microvascular flow in skin and mucosae laser Doppler instruments were introduced. PMID:14694774

Bollinger, Alfred; Partsch, Hugo

2003-11-01

162

Plasma rotation profile measurements using Doppler reflectometry  

International Nuclear Information System (INIS)

High spatial resolution radial profiles of the perpendicular plasma rotation velocity uperpendicular using a dual channel 50-75 GHz Doppler reflectometer system on the ASDEX Upgrade tokamak are presented for a variety of discharge scenarios, including Ohmic, L-mode, H-mode, etc with forward and reversed magnetic field and co- and counter neutral beam injection. The reflectometers have steppable launch frequencies fo c/?o, with selectable O- or X-mode polarization, giving tokamak edge to mid-radius coverage. Low-field-side antennae (hog-horn antenna pairs) with deliberate tilting (primarily poloidally) produce a Doppler shifted spectrum directly proportional to the perpendicular velocity fD uperpendicularkperpendicular/2? uperpendicular 2sin?t/?o. The incident angle ?t between the beam and cut-off layer normal varies with plasma shape, cut-off layer position and refraction. However, typical angles range from 50 to 270 giving a probed turbulence wavenumber, kperpendicular, range of 1.8-14.3 cm-1, with resulting Doppler shifts fD of up to 5 MHz. The measured perpendicular velocity is uperpendicular = vExB + vphase, which for a typical H-mode is slightly positive in the tokamak scrape-off-layer with a deep negative well across the H-mode steep pressure gradient pedestal ree steep pressure gradient pedestal region and then following the perpendicularly projected toroidal fluid velocity in the core, should be dominated by the E x B velocity, as the intrinsic phase velocity is predicted to be small, which may allow uperpendicular to be interpreted directly as the radial electric field Er profile

163

Prospects of Doppler cooling on forbidden lines  

International Nuclear Information System (INIS)

Doppler cooling on a forbidden transition is studied experimentally and numerically. By quenching the upper level of the cooling transition, the scattering rate is increased, and 106 40Ca atoms have been cooled and trapped in a magneto-optical trap to temperatures of down to 6 ?K. A model is developed that describes the cooling method by rate equations. Based on the model, Monte Carlo simulations are performed that show good agreement with the experimental results. Possibilities of reaching high densities and low temperature by optimizing the parameters during the cooling phase are discussed, and the benefit of these ultracold atoms for the accuracy and stability of optical frequency standards is demonstrated

164

Doppler spectrum-based polar nephelometer.  

Science.gov (United States)

The particle scattering asymmetry parameter of an ensemble of submicrometer particles, as well as the complete scattering phase function (angular distribution), is determined by measuring the Doppler spectrum of the scattered light. No calibration is required. The monitor incorporates a 532 nm laser with long coherence length, an integrating sphere to collect the scattered light, and a heterodyne (interferometric) detection scheme. Measurements of monodisperse polystyrene latex spheres and polydisperse ammonium sulfate particles indicate that the measured value of the asymmetry parameter is generally within ±0.03 of that calculated using Mie theory. PMID:22940980

Kebabian, Paul L; Onasch, Timothy B; Wormhoudt, Joda C; Freedman, Andrew

2012-09-01

165

Superheterodyne three-component laser Doppler anemometer  

International Nuclear Information System (INIS)

The design, method of tuning and principle of operation of a three-component laser Doppler anemometer with inverse-differential optical train are described. Employment of frequency-type light modulator with a 100% modulation factor permitting smooth variation of light frequency means that the anemometer can operate in superheterodyne mode. The range of measured velocities is within 1 mm/s - 50 m/s. Relative error of velocity measurement in a multi-particle mode was not in excess of 5%. Methodical opportunities of the instrument are demonstrated, using gas velocity field measurement by way of example

166

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.

2008-03-01

167

[Color Doppler sonography of focal abdominal lesions].  

Science.gov (United States)

Color Doppler sonography (CDS--spectral, color and power), harmonic imaging techniques (THI, PHI), possibility of 3D analysis of picture, usage of contrast agents, have raised the values of ultrasound as a diagnostic method to a very high level. THI--non-linear gray scale modality, is based on the processing of higher reflected frequencies, that has improved a picture resolution, which is presented with less artifacts and limiting effects of obesity and gases. Ultrasound contrast agents improve analysis of micro and macro circulation of the examined area, and with the assessment of velocity of supply in ROI (wash in), distribution and time of signal weakening (wash out), are significantly increasing diagnostic value of ultrasound. Besides the anatomical and topographic presentation of examined region (color, power), Color Doppler sonography gives us haemodynamic-functional information on vascularisation of that region, as well as on pathologic vascularisation if present. Avascular aspect of a focal pathologic lesion corresponds to a cyst or haematoma, while coloration and positive spectral curve discover that anechogenic lesions actually represents aneurysms, pseudoaneurysms or AVF. In local inflammatory lesion, abscess in an acute phase, CDS shows first increased, and then decreased central perfusion, while in a chronic phase, a pericapsular vascularisation is present. Contribution of CDS in differentiation of hepatic tumors (hemangioma, HCC and metastasis) is very significant. Central color dots along the peripheral blood vessels and the blush phenomenon are characteristics of capillary hemangioma, peritumoral vascular ring "basket" of HCC, and "detour" sign of metastasis. The central artery, RI from 0.45 to 0.60 and radial spreading characterize FNH. Hepatic adenoma is characterized by an intratumoral vein, and rarely by a vascular hallo. Further on, blood velocity in tumor defined by Color Doppler, distinguishes malignant from benign lesion, where 40 cm/s is a rough border value. Values of DPI (Doppler perfusion index) over 0.3 and tumor index over 1.0 characterize primary, and lower values characterize secondary liver malignancies. In differentiation of benign and malign tumors of kidneys, besides the aspect of vascularisation, the maximal frequency altitude in tumor artery (the limit around 2.5 kHz) is very important. However, peripheral and penetrating blood vessels are most usually seen in RCC, less often in AML and bigger oncocytomas. CDS with contrast agent is very useful in making differential diagnosis of the focal lesions with 95% specificity for some lesions. PMID:15137225

Licanin, Zoran; Lincender, Lidija; Djurovi?, V; Salihefendi?, Nizama; Smajlovi?, Fahrudin

2004-01-01

168

Railway wheels flat detector using Doppler effect  

Science.gov (United States)

A new inspection system for railway wheels using the Doppler Effect is presented in this work. The proposed system analyses the rail-wheel contact by frequency and phase shifts. Cracks on the wheel tread are determined while the train moves at a low speed. A special rail is used to propagate monochromatic surface waves. When a wheel on the measuring rail moves at constant speed, the received signal will present a regular frequency shift related with the movement speed. The difference between the emitted and the received frequencies will change if any defect on the wheel tread is detected.

Brizuela, Jose; Ibañez, Alberto; Nevado, Patricia; Fritsch, Carlos

2010-01-01

169

Power Doppler - Principles and Potential Clinical Applications  

OpenAIRE

The purpose of this work was to: a) Determine whether the amount of colour in a power Doppler image is dependent on the angle between the examined vessel and the soundbeam and/or on the velocity of the flow within the vessel; b) Investigate if a dependency on flow velocity could be used for the detection of volume flow differences and c) Define clinical applications utilising the improved sensitivity to low flow of PD. In the experimental studies (study I and II) a silicon tube in a water bat...

Nilsson, Anders

2003-01-01

170

Respiratory effort energy estimation using Doppler radar.  

Science.gov (United States)

Human respiratory effort can be harvested to power wearable biosensors and mobile electronic devices. The very first step toward designing a harvester is to estimate available energy and power. This paper describes an estimation of the available power and energy due to the movements of the torso during breathing, using Doppler radar by detecting breathing rate, torso displacement, torso movement velocity and acceleration along the sagittal movement of the torso. The accuracy of the detected variables is verified by two reference methods. The experimental result obtained from a healthy female human subject shows that the available power from circumferential movement can be higher than the power from the sagittal movement. PMID:23365993

Shahhaidar, Ehsaneh; Yavari, Ehsan; Young, Jared; Boric-Lubecke, Olga; Stickley, Cris

2012-01-01

171

Doppler effects in high spin spectroscopy  

International Nuclear Information System (INIS)

A systematic investigation of the different effects causing Doppler broadening when detecting ? rays following the depopulation of high spin nuclear states is performed. The size of the various effects is calculated or estimated to see how much they influence the resolution of ? lines at different emission angles. Simple formulas are used for most of the effects. The investigation has resulted in a program which calculates the broadening at any angle and also gives the detector collimators needed to get equal or accepted resolution at all angles. A concrete example on a calculation with this program is presented. (orig.)

172

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2002-07-01

173

Choroidal blood flow by laser Doppler flowmetry  

Science.gov (United States)

A method is described that provides measurements of blood flow (ChBF) in discrete regions of the choroidal vascular system. It is based on the technique of laser Doppler flowmetry (LDF). A diode laser beam (wavelength equals 810 nm, 60 (mu) W at the cornea) is delivered to the eye through a fundus camera. Light scattered by red blood cells in the tissue volume illuminated by the incident laser beam is detected at the fundus image plane of the camera by an optical fiber. Two analysis schemes of the Doppler signal are developed: one uses commercial skin blood flowmeters and the other a NeXTstation (Motorola 68040 based) computer system. Responses of ChBF to various stimuli are in good agreement with previously published findings in animals. LDF is a valid technique for obtaining noninvasive, continuous, and sensitive recordings of ChBF at discrete regions of the cat eye and in the foveal region of the human fundus, without the need to dilate the pupil.

Riva, Charles E.; Petrig, Benno L.

1995-03-01

174

The Doppler Wind and Temperature Sounder  

Science.gov (United States)

The Doppler Wind and Temperature Sounder (DWTS) is novel sensor concept for measuring global winds and temperatures from cloud-top to the thermosphere. This will significantly improve medium- and long-range weather forecasts and enable more advanced tracking of severe storms. The approach uses the inherent high spectral resolution from gas filter correlation radiometry to simultaneously measure the Doppler shift and linewidth of limb emission spectra as viewed from low-Earth orbit. DWTS images the limb through low-pressure gas cells containing CO2, NO and NO2. We describe here how very accurate vector winds and kinetic temperatures can be inferred from these observations. Profiles of temperature and wind can be measured day and night continuously from 15 to over 250 km at intervals of 10 km along-track with less than 2% uncertainty. A constellation of 6-12 DWTS instruments on small satellites would provide unprecedented observations of global atmospheric dynamics from the lower stratosphere into the middle thermosphere, greatly improving weather and storm forecasting. We present the current status and plans to realize this important mission.

McHugh, Martin; Fritts, Dave; Gordley, Larry

2014-06-01

175

Color doppler imaging of hepatic tumors  

International Nuclear Information System (INIS)

To evaluate the color Doppler imaging patterns of hepatoma, hemangioma, and metastasis. The study comprised 37 patients with liver mass lesions: 12 patients had hepatoma, 15 had hemangiomas and 10 had metastatic liver cancers. All 37, who showed hepatic mass on gray scale ultrasonogrphy, were analyzed prospectively. Color mapping of tumors was performed for these patients, and the fastest or next fastest vessel was spectrally analysed to show blood pattern and to measure peak velocity. In all the 12 patients with hepatoma, spectral analysis revealed exteusive pulsating arterial blood flow within the tumor;peak velocities were 7?65cm/sec(mean 34cm/sec). In ten hemangiomas(66%) color mapping revealed blood flow within the tumor and spectral analysis revealed this possibility in eight of the ten tumors. In none of these patients was a pulsating continous wave observed; peak velocity was 5?21cm/sec (mean 12.8cm/sec). In no mestastatic tumors was blood flow observed. Color Doppler imaging is helpful in the differentiation of hepatoma, hemangioma, and metastatic tumor in the liver

176

Research study: Severe storms Doppler lidar signal processing  

Science.gov (United States)

Four tasks related to the signal processing aspects of the severe-storms Doppler lidar program are discussed. The development of algorithms for windfield retrieval from Doppler lidar measurements are discussed. Signal processor installation on a CV-990 aircraft is discussed.

Lee, R. W.

1982-01-01

177

Infrared Doppler laser systems for the remote measurement of winds  

Energy Technology Data Exchange (ETDEWEB)

Theoretical principles are presented for the Doppler lidar measurement of wind velocity. A method for measuring the structural constant of wind velocity fields is proposed. A scheme of a continuous monostatic Doppler lidar is described, and results of full-scale and comparative measurements of wind velocity profiles and structural constant are reported. 10 refs.

Akhmanov, S.A.; Gordienko, V.M.; Kosovskii, L.A.; Kurochkin, N.N.; Pogosov, G.A. (Moskovskii Gosudarstvennyi Universitet, Moscow (USSR))

1991-02-01

178

Diagnosis of aortic dissection by color-coded doppler  

International Nuclear Information System (INIS)

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

179

Imaging doppler velocimeter with downward heterodyning in the optical domain  

Energy Technology Data Exchange (ETDEWEB)

In a Doppler velocimeter, the incoming Doppler-shifted beams are heterodyned to reduce their frequencies into the bandwidth of a digital camera. This permits the digital camera to produce at every sampling interval a complete two-dimensional array of pixel values. This sequence of pixel value arrays provides a velocity image of the target.

Reu, Phillip L; Hansche, Bruce D

2013-05-21

180

Analisis Efek Variasi Sudut Doppler terhadap Indeks Velocimetry Arteri Karotis  

OpenAIRE

Telah dilakukan penelitian untuk menganalisis efek variasi sudut Doppler terhadap indeks velocimetry arteri karotis dengan pengujian variasi sudut Doppler 20o, 40o, 60o dan 80o untuk mengetahui nilai indeks velocimetry arteri karotis berdasarkan perhitungan manual dan observasi, serta menganalisis adanya abnormalitas. Metode yang dilakukan adalah membandingkan hasil perhitungan manual dan observasi. Penelitian dilakukan dengan menggunakan analisis deskriptif, pengujian kesalahan pengukuran, u...

Isradiati, Dwi Febri; Halide, Halmar

2013-01-01

181

Physiological and pathophysiological cerebrovascular regulation monitored by transcranial doppler  

OpenAIRE

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

Hellstro?m, Gunnar

1997-01-01

182

Laser Doppler velocimetry and its application to turbulent flow measurements  

International Nuclear Information System (INIS)

The present state of development is reviewed of laser Doppler velocimetry, a new method of fluid flow characteristic measurement. The physical principles involved, the classification of the optical schemes utilized, the typical experimental arrangements, the nature of the laser Doppler velocimeter signal and methods of signal analysis are discussed. The comprehensive bibliography contains more than 300 references from 1964 to 1974. (author)

183

?rinciple of relativity in navigation for example doppler meter speed  

Directory of Open Access Journals (Sweden)

Full Text Available  There is considered in article the analysis of radio navigation system errors, are determined by the requirements accoroling to the movement of receiver, and transmitter, which are located on the moving objects, i.e. by the “relativists” phenomena; is represented the estimation methodic of acceleration using other Doppler’s device and the acceleration of one aircraft relative to another.

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2006-01-01

184

Micro-Doppler classification of riders and riderless horses  

Science.gov (United States)

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

Tahmoush, David

2014-05-01

185

Is Doppler tissue velocity during early left ventricular filling preload independent?  

OpenAIRE

Background: Transmitral Doppler flow indices are used to evaluate diastolic function. Recently, velocities measured by Doppler tissue imaging have been used as an index of left ventricular relaxation.

Yalc?in, F.; Kaftan, A.; Muderrisog?lu, H.; Korkmaz, M. E.; Flachskampf, F.; Garcia, M.; Thomas, J. D.

2002-01-01

186

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

187

Use of GPS network data for HF Doppler measurements interpretation  

CERN Document Server

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

Petrova, Inna R; Latypov, Ruslan R

2014-01-01

188

LISA data analysis; 1, Doppler demodulation  

CERN Document Server

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

Cornish, N; Cornish, Neil; Larson, Shane

2003-01-01

189

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

190

Widefield laser doppler velocimeter: development and theory.  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-03-01

191

Microscale Heat Conduction Models and Doppler Feedback  

Energy Technology Data Exchange (ETDEWEB)

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

Hawari, Ayman I.; Ougouag, Abderrafi

2015-01-22

192

Laser Doppler flowmetry in manual medicine research.  

Science.gov (United States)

Laser Doppler flowmetry (LDF) is commonly used in combination with reactivity tests to noninvasively evaluate skin sympathetic nerve activity and skin microvascular function. In manual medicine research, LDF has been used as a marker for global peripheral sympathetic nervous system function, but these results should be considered with caution because skin sympathetic nerve activity physiology is often overlooked. Another limitation of LDF in manual medicine research is the processing of LDF recordings. Two methods have been suggested: the time-domain analysis and the frequency-domain analysis. Standardization is required for data collection and processing in either domain to accurately interpret these changes in skin blood flow that occur after manual procedures. For physiologic studies using LDF, the authors recommend the use of noninvasive reactivity tests (positive controls) to evaluate the different mechanisms involved in overall skin blood flow changes and to compare the magnitude of these changes with those specifically elicited by manual procedures. PMID:25429081

Zegarra-Parodi, Rafael; Snider, Eric J; Park, Peter Yong Soo; Degenhardt, Brian F

2014-12-01

193

Doppler cooling and trapping on forbidden transitions  

CERN Document Server

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

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

2001-01-01

194

Transcranial doppler, EEG and SEP monitoring  

Directory of Open Access Journals (Sweden)

Full Text Available The role of neuromonitoring in the prevention of cerebral damage associated with cardiosurgical interventions has not yet been clearly elucidated. Reliable randomised studies from evidence-based medicine showing a clear reduction of risk do not exist. Numerous studies and reviews however, have confirmed that non-invasive procedures for monitoring neuronal or neurophysiological changes before, during and after interventions within the heart or the major thoracic vessels are available and provide early indications of damage.Technological modalities and clinical indications for non invasive cerebral monitoring were evaluated:Electroencephalography (EEG with processed EEG, bispectral index (BIS and the evoked potential for use with spinal cord functionNear infrared spectroscopy (NIRS for assessment of cerebral perfusion and oxygenationTranscranial Doppler sonography (TCDS for assessment of cerebral circulation and perfusionMultimodality monitoring as a combination of EEG, NIRS and TCDS.

A. Opp

2009-07-01

195

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

196

[Improved structure identification with tissue Doppler echocardiography].  

Science.gov (United States)

Tissue Doppler echocardiography (TDE) has been shown to be of particular value in patients with impaired myocardial function. Recently, the technique was successfully employed to localize the ventricular insertion of accessory atrioventricular pathways. The identification of abnormal cardiac structures is coming up now as a new field of clinical interest. The purpose of this study was to differentiate anomalous cardiac and aortic from native structures by physical properties of tissue motion using transesophageal TDE. Characteristic motion patterns of anomalous structures have not been described in detail and tissue Doppler findings have not been associated with clinical features up to now. Forty consecutive patients were included after anomalous cardiac or vascular structures had been detected by conventional transesophageal echocardiography (TEE). A control group consisted of 20 subjects. Rapidity of diagnosis in anomalous structures was divided into 3 categories, and TDE signals were related to particular pathology by a blinded, 2nd observer. Three different motion patterns could be defined: incoherent motion due to free oscillation of an anomalous structure which is independent of the surrounding tissue (Figure 1b); coherent motion with a phase difference meaning that motion depends on the motion of the surrounding tissue but is out of phase (Figure 2); concordant motion showing no difference in direction, velocity, or phase of motion compared with the surrounding tissue. Incoherent motion was present in endocarditic vegetations, 4th degree aortic plaques, Chiari network, valvular prolapse, intracavitary tumors, and freely oscillating thrombi as well as in normal valve leaflets and papillary muscles. Especially if endocarditic vegetations are present its incoherent motion facilitates to recognize these small structures. The colorcode of this motion pattern demarcates the vegetation reliably from the surrounding tissue (Figure 1b). Within 15 seconds vegetations could be detected in 9 (82%) vs 2 (18%) patients employing only conventional imaging. Using conventional echocardiographic approaches detection of vegetations is frequently hindered by their small size and minor echo intensity (Figure 1a). In contrast, size and echo intensity do not affect the tissue Doppler signal. Normal papillary muscles and distal portions of the mitral and tricuspid valves were demonstrated to regularly meet the criterion of incoherent tissue motion in the control group. In part, this was also observed with respect to the aortic and pulmonary valves. In valvular tissue incoherent motion was caused by passive floating, whereas papillary muscles show an active inverse motion for short time intervals. Nevertheless, physiologic incoherent motion did not lead to any false differential diagnosis. The phase difference of coherent motion results from damped oscillation. This phenomenon was visualized by tissue Doppler M-mode in 5 thrombi of the left atrial appendage (LAA) (100%) and in 1 ventricular thrombus (50% of all clots). Concordant motion was shown in 3rd degree aortic plaques and postrheumatic and calcified vegetations. These structures were found to be completely embedded or closely attached, so that their passive motion corresponded to the motion of the surrounding regular tissue. Detection and assessment of anomalous structures are based on their motion patterns which can be synchronous or asynchronous in comparison with the surrounding tissue. Another goal of this investigation was to test if the sensitivity of TEE to spontaneous echo contrast can be improved using TDE. In 21 patients presenting with left atrial dilation (left atrial diameter > 44 mm) due to mitral stenosis (n = 8), mitral regurge (n = 5), arterial hypertension (n = 5) and multiple valvular disease (n = 3) fundamental multiplane TEE and transesophageal TDE were performed with standardized gain setting. The control group consisted of 20 randomized individuals with normal left PMID:10023584

Bartel, T; Müller, S; Möhlenkamp, S; Bruch, C; Schaar, J; Erbel, R

1998-12-01

197

Application of wavelet analysis in laser Doppler vibration signal denoising  

Science.gov (United States)

Large number of experiments show that, due to external disturbances, the measured surface is too rough and other factors make use of laser Doppler technique to detect the vibration signal contained complex information, low SNR, resulting in Doppler frequency shift signals unmeasured, can not be demodulated Doppler phase and so on. This paper first analyzes the laser Doppler signal model and feature in the vibration test, and studies the most commonly used three ways of wavelet denoising techniques: the modulus maxima wavelet denoising method, the spatial correlation denoising method and wavelet threshold denoising method. Here we experiment with the vibration signals and achieve three ways by MATLAB simulation. Processing results show that the wavelet modulus maxima denoising method at low laser Doppler vibration SNR, has an advantage for the signal which mixed with white noise and contained more singularities; the spatial correlation denoising method is more suitable for denoising the laser Doppler vibration signal which noise level is not very high, and has a better edge reconstruction capacity; wavelet threshold denoising method has a wide range of adaptability, computational efficiency, and good denoising effect. Specifically, in the wavelet threshold denoising method, we estimate the original noise variance by spatial correlation method, using an adaptive threshold denoising method, and make some certain amendments in practice. Test can be shown that, compared with conventional threshold denoising, this method is more effective to extract the feature of laser Doppler vibration signal.

Lan, Yu-fei; Xue, Hui-feng; Li, Xin-liang; Liu, Dan

2010-10-01

198

Clutter reduction using Doppler sonar in a harbor environment.  

Science.gov (United States)

A high frequency experiment was conducted in the Woods Hole Harbor in Massachusetts to evaluate the effectiveness of Doppler sonar for discriminating targets from reverberation. Using a pulsed linear frequency modulated signal, one finds that the matched filtered outputs are filled with high-level discrete backscattered returns, referred to as clutter, which are often confused with the target echo. The high level non-target returns have an amplitude distribution that is heavy-tailed. Using a Doppler-sensitive binary-phase-shift-keying signal coded with an m-sequence, the target echo and clutter can be separated by Doppler and delay, and tracked using the Doppler spectrogram (Dopplergram). The Doppler filtered time series show a background reverberation with a Rayleigh-like amplitude distribution, with an improved signal-to-(peak) reverberation ratio compared with that without Doppler filtering. The reduced reverberation level with Doppler processing decreases the probability of false alarm (Pfa) for a given threshold level. Conversely, for a given Pfa, the higher signal-to-(peak) reverberation ratio implies a higher probability of detection. Transmission loss measurement was conducted to estimate some of the system parameters, e.g., the source level and target strength relative to the noise level. PMID:23145591

Yang, T C; Schindall, J; Huang, Chen-Fen; Liu, Jin-Yuan

2012-11-01

199

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

200

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

201

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

Energy Technology Data Exchange (ETDEWEB)

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.

Chen, K [Banner Alzheimer Institute and Banner Good Samaritan Positron Emission Tomography (PET) Center, Phoenix, AZ (United States); Chen, X [Div Computer Stud, Arizona State University, Mesa, AZ (United States); Renaut, R [Department of Mathematics and Statistics, Arizona State University, Tempe, AZ (United States); Alexander, G E [Arizona Alzheimer' s Consortium, Phoenix, AZ (United States); Bandy, D [Banner Alzheimer Institute and Banner Good Samaritan Positron Emission Tomography (PET) Center, Phoenix, AZ (United States); Guo, H [Department of Mathematics and Statistics, Arizona State University, Tempe, AZ (United States); Reiman, E M [Banner Alzheimer Institute and Banner Good Samaritan Positron Emission Tomography (PET) Center, Phoenix, AZ (United States)

2007-12-07

202

Pulsed Doppler echocardiographic analysis of mitral regurgitation after myocardial infarction.  

Science.gov (United States)

In 72 patients with previous myocardial infarction (MI), mitral regurgitation (MR) was assessed by pulsed-wave Doppler echocardiography and compared with physical and 2-dimensional echocardiographic findings. MR was found by Doppler in 29 of 42 patients (62%) with anterior MI, 11 of 30 (37%) with inferior MI (p less than 0.01) and in none of 20 normal control subjects. MR was more frequent in patients who underwent Doppler study 3 months after MI than in those who underwent Doppler at discharge (anterior MI = 83% vs 50%, p less than 0.01; inferior MI = 47% vs 27%, p = not significant). Of 15 patients who underwent Doppler studies both times, 3 (all with anterior MI) had MR only on the second study. Of the patients with Doppler MR, 12 of 27 (44%) with a left ventricular (LV) ejection fraction (EF) greater than 30% and 1 of 13 (8%) with an EF of 30% or less (p less than 0.01) had an MR systolic murmur. Mitral prolapse or eversion and papillary muscle fibrosis were infrequent in MI patients, whether or not Doppler MR was present. The degree of Doppler MR correlated with EF (r = -0.61), LV systolic volume (r = 0.47), and systolic and diastolic mitral anulus circumference (r = 0.52 and 0.51, respectively). Doppler MR was present in 24 of 28 patients (86%) with an EF of 40% or less and in 16 of 44 (36%) with EF more than 40% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3766410

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

1986-10-01

203

Processor operated correlator with applications to laser Doppler signals  

OpenAIRE

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

204

A comparison of Doppler optical coherence tomography methods  

OpenAIRE

Abstract: We compare, in detail, the phase-resolved color Doppler (PRCD), phase-resolved Doppler variance (PRDV) and intensity-based Doppler variance (IBDV) methods. All the methods are able to quantify flow speed when the flow rate is within a certain range, which is dependent on the adjacent A-line time interval. While PRCD is most sensitive when the flow direction is along the probing beam, PRDV and IBDV can be used to measure the flow when the flow direction is near perpendicular to the p...

Liu, Gangjun; Lin, Alexander J.; Tromberg, Bruce J.; Chen, Zhongping

2012-01-01

205

A Modified Modulation Recognition Method against Doppler Effects  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, we present a modified modulation recognition method- the way to seek the slope (TW-STS, based on decision theory, which can classify 7 kinds of basic digital modulation signals well under the influence of Doppler Effect. The proposed scheme is obtained by analyzing the influence to instantaneous amplitude, instantaneous phase and instantaneous frequency caused by Doppler Effect and modifying the original modulation recognition model. It can retrain the influence well and then we can get high recognition rate. In actual band-limited channel, the Doppler Effect to the modulation recognition is more complex.

Yaqin Zhao

2011-01-01

206

Sub-Doppler laser cooling of potassium atoms  

International Nuclear Information System (INIS)

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

207

Assessment of human tumor vascularity: Doppler color flow mapping  

International Nuclear Information System (INIS)

A new Doppler color flow image (Quantum Medical Systems, Issaquah, Wash.) was used to evaluate the vascularity of tumors in 25 patients. Benign and malignant tumors of the breast, thyroid, liver, kidney, and superficial soft tissues were studied. The system used allows simultaneous display of high-resolution gray-scale tissue information and Doppler flow data. Most malignant tumors have shown hypervascularity with a peripheral distribution of abnormal vessels. Flow within vessels as small as 1-2 mm can be demonstrated with this system. The results suggest that Doppler color flow imaging may aid in characterization of masses seen on US

208

Phase modulation of propagation effect with Doppler broadening  

International Nuclear Information System (INIS)

This paper studies the propagation effect in a closed lambda-type three-level atomic system with Doppler broadening. It is shown that, Doppler broadening due to atomic motion and propagation effect associated with driving field depletion along the active medium decreases obviously the gain and output of the lasing without inversion (LWI); the relative phase between the probe and driving fields has a remarkable modulation role to the propagation effect on LWI when Doppler broadening presents; by choosing suitable value of the relative phase, we can get the largest gain and output of LWI. (classical areas of phenomenology)

209

Relativistic formulation for the Doppler-broadened line profile  

International Nuclear Information System (INIS)

Profiles of spectral lines due to the thermal motion of light-emitting particles are formulated based on the classical and the relativistic Doppler effects, respectively. For the classical case, the well-known Doppler-broadened line profile is reproduced. For the relativistic case, the line profile obtained is asymmetrically broadened with increasing temperature. However, the peak frequency remains unshifted, in contrast to blueshifted, as has been predicted in the current literature. Reasoning is given as to why the relativistic Doppler-broadened line profile currently accepted is probably invalid.

210

Doppler ultrasound signal denoising based on wavelet frames.  

Science.gov (United States)

A novel approach was proposed to denoise the Doppler ultrasound signal. Using this method, wavelet coefficients of the Doppler signal at multiple scales were first obtained using the discrete wavelet frame analysis. Then, a soft thresholding-based denoising algorithm was employed to deal with these coefficients to get the denoised signal. In the simulation experiments, the SNR improvements and the maximum frequency estimation precision were studied for the denoised signal. From the simulation and clinical studies, it was concluded that the performance of this discrete wavelet frame (DWF) approach is higher than that of the standard (critically sampled) wavelet transform (DWT) for the Doppler ultrasound signal denoising. PMID:11381694

Zhang, Y; Wang, Y; Wang, W; Liu, B

2001-05-01

211

Measurement depth and volume in laser Doppler flowmetry  

OpenAIRE

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

212

The Next Generation Airborne Polarimetric Doppler Radar  

Science.gov (United States)

NCAR's Electra Doppler radar (ELDORA) with a dual-beam slotted waveguide array using dual-transmitter, dual-beam, rapid scan and step-chirped waveform significantly improved the spatial scale to 300m (Hildebrand et al. 1996). However, ELDORA X-band radar's penetration into precipitation is limited by attenuation and is not designed to collect polarimetric measurements to remotely estimate microphysics. ELDORA has been placed on dormancy because its airborne platform (P3 587) was retired in January 2013. The US research community has strongly voiced the need to continue measurement capability similar to the ELDORA. A critical weather research area is quantitative precipitation estimation/forecasting (QPE/QPF). In recent years, hurricane intensity change involving eye-eyewall interactions has drawn research attention (Montgomery et al., 2006; Bell and Montgomery, 2006). In the case of convective precipitation, two issues, namely, (1) when and where convection will be initiated, and (2) determining the organization and structure of ensuing convection, are key for QPF. Therefore collocated measurements of 3-D winds and precipitation microphysics are required for achieving significant skills in QPF and QPE. Multiple radars in dual-Doppler configuration with polarization capability estimate dynamical and microphysical characteristics of clouds and precipitation are mostly available over land. However, storms over complex terrain, the ocean and in forest regions are not observable by ground-based radars (Bluestein and Wakimoto, 2003). NCAR/EOL is investigating potential configurations for the next generation airborne radar that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. ELDORA's slotted waveguide array radar is not compatible for dual-polarization measurements. Therefore, the new design has to address both dual-polarization capability and platform requirements to replace the ELDORA system. NCAR maintains a C-130 aircraft in its fleet for airborne atmospheric measurements, including dropsonde, and in situ sampling and remote sensing of clouds, chemistry and aerosols. Therefore, the addition of a precipitation radar to the NSF/NCAR C-130 platform will produce transformational change in its mission. This new design can be cloned for C-130s operated by a number of agencies, including NOAA and the Air Force hurricane reconnaissance fleet. This paper presents a possible configuration of a novel, airborne phased array radar (APAR) to be installed on the NSF/NCAR C-130 aircraft with improved spatial resolution and polarimetric capability to meet or exceed that of ELDORA. The preliminary design, an update of the APAR project, and a future plan will be presented. References: Bell, M. M. , M. T. Montgomery, 2008: Observed Structure, Evolution, and Potential Intensity of Category 5 Hurricane Isabel (2003) from 12 to 14 September. Monthly Weather Review, Vol. 136, Issue 6, pp. 2023-2046. Hildebrand, P. H., W.-C. Lee, C. A. Walther, C. Frush, M. Randall, E. Loew, R. Neitzel, R. Parsons, J. Testud, F. Baudin, and A. LeCornec, 1996: The ELDORA/ASTRAIA airborne Doppler weather radar: High resolution observations from TOGA COARE. Bull. Amer. Metoro. Soc., 77, 213-232 Howard B. Bluestein, Roger M. Wakimoto, 2003: Mobile Radar Observations of Severe Convective Storms re Convective Storms. Meteorological Monographs, Vol. 30, Issue 52, pp. 105-105. Montgomery, M. T., M. M. Bell, S. D. Aberson, M. L. Black, 2006: Hurricane Isabel (2003): New Insights into the Physics of Intense Storms. Part I: Mean Vortex Structure and Maximum Intensity Estimates. Bull. of the American Meteorl. Soc., Vol. 87, Issue 10, pp. 1335-1347.

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

2013-04-01

213

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

214

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.)

215

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

216

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

217

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

218

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

219

Micro-Doppler processing for ultra-wideband radar data  

Science.gov (United States)

In this paper, we describe an operational pulse Doppler radar imaging system for indoor target localization and classification, and show how a target's micro-Doppler signature (?DS) can be processed when ultra-wideband (UWB) waveforms are employed. Unlike narrowband radars where time-frequency signal representations can be applied to reveal the target time-Doppler frequency signatures, the UWB system permits joint range-time-frequency representation (JRTFR). JRTFR outputs the data in a 3D domain representing range, frequency, and time, allowing both the ?DS and high range resolution (HRR) signatures to be observed. We delineate the relationship between the ?DS and the HRR signature, showing how they would form a complimentary joint feature for classification. We use real-data to demonstrate the effectiveness of the UWB pulse-Doppler radar, combined with nonstationary signal analyses, in gaining valuable insights into human positioning and motions.

Smith, Graeme E.; Ahmad, Fauzia; Amin, Moeness G.

2012-06-01

220

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

221

A Digital Multigate Doppler Method for High Frequency Ultrasound  

Directory of Open Access Journals (Sweden)

Full Text Available Noninvasive visualization of blood flow with high frequency Doppler ultrasound has been extensively used to assess the morphology and hemodynamics of the microcirculation. A completely digital implementation of multigate pulsed-wave (PW Doppler method was proposed in this paper for high frequency ultrasound applications. Analog mixer was eliminated by a digital demodulator and the same data acquisition path was shared with traditional B-mode imaging which made the design compact and flexible. Hilbert transform based quadrature demodulation scheme was employed to achieve the multigate Doppler acquisition. A programmable high frequency ultrasound platform was also proposed to facilitate the multigate flow visualization. Experimental results showed good performance of the proposed method. Parabolic velocity gradient inside the vessel and velocity profile with different time slots were acquired to demonstrate the functionality of the multigate Doppler. Slow wall motion was also recorded by the proposed method.

Weibao Qiu

2014-07-01

222

Doppler Signatures of the Atmospheric Circulation on Hot Jupiters  

CERN Document Server

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

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

2013-01-01

223

Calculation of doppler coefficient of reactivity by WIMS code  

International Nuclear Information System (INIS)

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

224

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

225

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

226

Gravitational waves from coalescing binaries and Doppler experiments  

OpenAIRE

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...

Bertotti, Bruno; Vecchio, Alberto; Iess, Luciano

1998-01-01

227

Sizing Gaseous Emboli Using Doppler Embolic Signal Intensity  

OpenAIRE

Extension of transcranial Doppler embolus detection to estimation of bubble size has historically been hindered by difficulties in applying scattering theory to the interpretation of clinical data. This article presents a simplified approach to the sizing of air emboli based on analysis of Doppler embolic signal intensity, by using an approximation to the full scattering theory that can be solved to estimate embolus size. Tests using simulated emboli show that our algorithm is theoretically c...

Banahan, Caroline; Hague, James P.; Evans, David H.; Patel, Rizwan; Ramnarine, Kumar V.; Chung, Emma M. L.

2012-01-01

228

A Modified Modulation Recognition Method against Doppler Effects  

OpenAIRE

In this study, we present a modified modulation recognition method- the way to seek the slope (TW-STS), based on decision theory, which can classify 7 kinds of basic digital modulation signals well under the influence of Doppler Effect. The proposed scheme is obtained by analyzing the influence to instantaneous amplitude, instantaneous phase and instantaneous frequency caused by Doppler Effect and modifying the original modulation recognition model. It can retrain the influence well and then ...

Yaqin Zhao; Song Chen; Hang Yu; Zhenguo Shi

2011-01-01

229

Cerebral blood velocity in subarachnoid haemorrhage: a transcranial Doppler study.  

OpenAIRE

A study examining the utility of transcranial Doppler ultrasound for the determination of cerebral vasospasm following subarachnoid haemorrhage is reported. A control group of 21 patients and a second group of 20 patients suffering from subarachnoid haemorrhage or aneurysm and a group of 26 with other intracranial pathologies were studied. The Doppler flow velocity (DFV) was significantly higher when vasospasm was present. If it was higher than 100 cm/s, the patients were found to have vasosp...

Compton, J. S.; Redmond, S.; Symon, L.

1987-01-01

230

Vein Thrombosis Associated with Umbilical Vascular Catheters with Color Doppler  

OpenAIRE

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 new...

Masoud Nemati; Manijeh Mostafa Gharehbaghi; Abolhassan Shakeri; Reza Taei Nobari; Noushin Behravan; Mohamad Goldust

2013-01-01

231

Multiple and dependent scattering effects in Doppler optical coherence tomography  

OpenAIRE

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

Kalkman, J.; Bykov, A. V.; Faber, D. J.; Leeuwen, T. G.

2010-01-01

232

Assessment of endometrial receptivity by Color Doppler and ultrasound imaging  

OpenAIRE

Introduction: Color Doppler sonography is a new method used to investigate changes during the menstrual cycle in infertile women. The objective of this study was to investigate the correlation of uterine and endomterial-subendomterial blood flow in infertile women using ultrasound and color Doppler sonography. Material and methods: A prospective clinical study included 65 infertile women divided into three groups. Transvaginal ultrasound examination was performed on days XI, XIV and XX. All r...

Lili? Vekoslav; Tubi?-Pavlovi? Aleksandra; Radovi?-Janoševi? Dragana; Petri? Aleksandra; Stefanovi? Milan; Živadinovi? Radomir

2007-01-01

233

Doppler ultrasonographic changes in the canine kidney during normovolaemic anaemia  

OpenAIRE

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...

Koma, L. M.; Kirberger, Robert M.; Scholtz, L.

2006-01-01

234

An automated carotid pulse assessment approach using Doppler ultrasound  

OpenAIRE

During cardiac arrest emergencies, lay rescuers are required to manually check the patient's carotid pulse after the delivery of defibrillation shocks to assess the cardiac resuscitation progress of the patient. As a more automated way of monitoring the resuscitation progress, a new Doppler-ultrasound-based carotid pulse assessment approach is presented in this paper. The method works by analyzing the temporal aperiodicity of Doppler shifts seen in the ultrasound echoes returned from the pati...

Yu, Ach; Cohensolal, E.; Raju, Bi; Ayati, S.

2008-01-01

235

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 naturThe 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

236

Epicardial coronary artery Doppler: Validation in the animal model  

OpenAIRE

The aim of the study was to validate a newly-designed epicardial coronary artery Doppler probe and test its detection of changes in coronary blood flow velocity. Left anterior descending (LAD) coronary blood flow and flow velocity were evaluated in four pigs with a pericoronary transit time flow (TTF) probe and a newly-designed epicardial Doppler micro-probe. Four consecutive measurements were taken for each of the following conditions: basal, partial stenosis, occlusion, and reperfusion of t...

D Ancona, G.; Hartman, J. M.; Bartolozzi, F.; Deel, E. D.; Duncker, D. J. G. M.; Bogers, A. J. J. C.; Pilato, M.; Kappetein, A. P.

2008-01-01

237

A pulsed CO2 Doppler lidar for boundary layer monitoring  

Science.gov (United States)

A monostatic, master oscillator power amplifier (MOPA), CO2 pulsed Doppler lidar was constructed and tested. The system is compact (120 x 60 cm), operates at high pulse repetition rates (greater than 1 kHz) and is intended for simultaneous Doppler/Differential Absorption Lidar (DIAL) monitoring of the planetary boundary layer. Details of the system design, hard target calibrations, and aerosol returns are presented.

Pearson, Guy N.

1992-01-01

238

A characteristic continuous wave Doppler signal in cor triatriatum?  

OpenAIRE

Continuous wave Doppler recordings of the turbulent jet through the restrictive orifice of a left atrial partition in a patient with corrected transposition of the great arteries and cor triatriatum showed alternate bands of high intensity diastolic and low intensity systolic signals with preservation of the normal configuration of the diastolic E and A peaks. It is thought that Doppler studies in cor triatriatum will provide useful complementary haemodynamic information in the echocardiograp...

Glaser, Joram

1993-01-01

239

Large Doppler Compensation for Mobile OFDM Based Underwater Acoustic Communication  

OpenAIRE

In this study, large Doppler compensation for Orthogonal Frequency Division Multiplexing (OFDM) suitable for mobile underwater acoustic communication is proposed. The scheme is applicable to underwater acoustic communication between rapidly moving platforms. Considering the structural characteristics of OFDM symbols, re-sampling and time-frequency differential code mapping are used to realize the broadband and narrowband Doppler compensation. The experimental results prove the feasibility of ...

Zhengrong Pan; Chi Wang; Jingwei Yin

2013-01-01

240

Use of GPS network data for HF Doppler measurements interpretation  

OpenAIRE

The method of measurement of Doppler frequency shift of ionospheric signal - HF Doppler technique - is one of well-known and widely used methods of ionosphere research. It allows to research various disturbances in the ionosphere. There are some sources of disturbances in the ionosphere. These are geomagnetic storms, solar flashes, metrological effects, atmospheric waves. This method allows to find out the influence of earthquakes, explosions and other processes on the ionos...

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

2014-01-01

241

Color doppler ultrasound diagonosis in cesarean scar pregnancy  

International Nuclear Information System (INIS)

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

242

Holographic laser Doppler imaging of microvascular blood flow  

OpenAIRE

We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with a frequency shifted reference beam, permits frequency selective imaging in the radiofrequency range. These Doppler images are acquired with an off axis Mach Zehnder interferometer. Microvascular hemodynamic components mapping is performed in the cerebral ...

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

2014-01-01

243

Using doppler radar images to estimate aircraft navigational heading error  

Science.gov (United States)

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

Prospects for Doppler cooling of three-electronic-level molecules  

OpenAIRE

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

245

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.)

246

Doppler hemodynamic study in evaluation of liver metastases  

OpenAIRE

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. .

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

2007-01-01

247

Doppler hemodynamic study in evaluation of liver metastases  

Directory of Open Access Journals (Sweden)

Full Text Available 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. .

Juriši? V.

2007-01-01

248

Special Theory of Relativity through the Doppler Effect  

OpenAIRE

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

Moriconi, M.

2006-01-01

249

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

250

Unsupervised dealiasing and denoising of color-Doppler data.  

Science.gov (United States)

Color Doppler imaging (CDI) is the premiere modality to analyze blood flow in clinical practice. In the prospect of producing new CDI-based tools, we developed a fast unsupervised denoiser and dealiaser (DeAN) algorithm for color Doppler raw data. The proposed technique uses robust and automated image post-processing techniques that make the DeAN clinically compliant. The DeAN includes three consecutive advanced and hands-off numerical tools: (1) statistical region merging segmentation, (2) recursive dealiasing process, and (3) regularized robust smoothing. The performance of the DeAN was evaluated using Monte-Carlo simulations on mock Doppler data corrupted by aliasing and inhomogeneous noise. Fifty aliased Doppler images of the left ventricle acquired with a clinical ultrasound scanner were also analyzed. The analytical study demonstrated that color Doppler data can be reconstructed with high accuracy despite the presence of strong corruption. The normalized RMS error on the numerical data was less than 8% even with signal-to-noise ratio as low as 10dB. The algorithm also allowed us to recover highly reliable Doppler flows in clinical data. The DeAN is fast, accurate and not observer-dependent. Preliminary results showed that it is also directly applicable to 3-D data. This will offer the possibility of developing new tools to better decipher the blood flow dynamics in cardiovascular diseases. PMID:21482175

Muth, Stéphan; Dort, Sarah; Sebag, Igal A; Blais, Marie-Josée; Garcia, Damien

2011-08-01

251

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

252

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-07-01

253

Muscle activity characterization by laser Doppler Myography  

International Nuclear Information System (INIS)

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

254

Helmet-mounted choroidal laser Doppler flowmeter  

Science.gov (United States)

A compact laser Doppler flowmeter (35x80x210mm3) for the measurement of subfoveal choroidal blood flow parameters (ChBF) was mounted on a helmet. This device allows the measurement of ChBF during dynamic exercises or in supine position, without the need for pupil dilatation. Its optical system is based on a Schlieren arrangement by which the surface of light collection and that of the illumination are spatially separated by an obscuration. The laser probing beam ((lambda) equals 790 nm, 100 (mu) W at the cornea) is focused at the fovea by having the tested subject look directly at the beam. Computer analysis of the photocurrent produced by the scattered light provides a relative measure of the mean blood velocity, number and flux of the red blood cells in the choriocapillaris. Measurements were performed to assess the reliability of the flow parameters measurements in normal volunteers: reproducibility and sensibility when subjects are sitting or standing; measurement of changes in ChBF in the case of isometric and dynamic exercises. Results demonstrate that this new helmet-mounted device provides data comparable to the conventional device. It allows for the first time, however, the continuous measurement of choroidal hemodynamics in humans during various types of exercises.

Geiser, Martial H.; Moret, Fabrice; Riva, Charles E.

2001-06-01

255

Atmospheric aerosol and Doppler lidar studies  

Science.gov (United States)

Experimental and theoretical studies were performed of atmospheric aerosol backscatter and atmospheric dynamics with Doppler lidar as a primary tool. Activities include field and laboratory measurement and analysis efforts. The primary focus of activities related to understanding aerosol backscatter is the GLObal Backscatter Experiment (GLOBE) program. GLOBE is a multi-element effort designed toward developing a global aerosol model to describe tropospheric clean background backscatter conditions that Laser Atmospheric Wind Sounder (LAWS) is likely to encounter. Two survey missions were designed and flown in the NASA DC-8 in November 1989 and May to June 1990 over the remote Pacific Ocean, a region where backscatter values are low and where LAWS wind measurements could make a major contribution. The instrument complement consisted of pulsed and continuous-wave (CW) CO2 gas and solid state lidars measuring aerosol backscatter, optical particle counters measuring aerosol concentration, size distribution, and chemical composition, a filter/impactor system collecting aerosol samples for subsequent analysis, and integrating nephelometers measuring visible scattering coefficients. The GLOBE instrument package and survey missions were carefully planned to achieve complementary measurements under clean background backscatter conditions.

Rothermel, Jeff; Bowdle, D. A.; Srivastava, V.; Jarzembski, M.; Cutten, D.; Mccaul, E. W., Jr.

1991-01-01

256

Doppler radar detection of vortex hazard indicators  

Science.gov (United States)

Wake vortex experiments were conducted at White Sands Missile Range, NM using the AN/MPS-39 Multiple Object Tracking Radar (MOTR). The purpose of these experiments was twofold. The first objective was to verify that radar returns from wake vortex are observed for some time after the passage of an aircraft. The second objective was to verify that other vortex hazard indicators such as ambient wind speed and direction could also be detected. The present study addresses the Doppler characteristics of wake vortex and clear air returns based upon measurements employing MOTR, a very sensitive C-Band phased array radar. In this regard, the experiment was conducted so that the spectral characteristics could be determined on a dwell to-dwell basis. Results are presented from measurements of the backscattered power (equivalent structure constant), radial velocity and spectral width when the aircraft flies transverse and axial to the radar beam. The statistics of the backscattered power and spectral width for each case are given. In addition, the scan strategy, experimental test procedure and radar parameters are presented.

Nespor, Jerald D.; Hudson, B.; Stegall, R. L.; Freedman, Jerome E.

1994-01-01

257

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

258

Theoretical Analysis of the Processof Doppler and Doppler Rate Estimation in Standard and High Sensitivity GNSS Receivers  

OpenAIRE

Due to the capability of the Global Positioning System (GPS) to provide accurate, stablelong-term navigation information, the use of a GPS receiver as a velocity and accelerationsensor has gained an increasing research interest. Navigation and control, airbornegravimetry and integration with inertial navigation systems (INS) are just some of thepotential applications. GPS velocity and acceleration measurements are typically determined using Doppler and Doppler rate observations provided by th...

Sokolova, Nadezda

2011-01-01

259

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

260

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

Directory of Open Access Journals (Sweden)

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

R.O. Carvalho

2006-06-01

261

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

Scientific Electronic Library Online (English)

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

R.O., Carvalho; R.B., Araújo; E.F., Silva.

2006-06-01

262

Doppler optical coherence tomography in cardiovascular applications  

Science.gov (United States)

The study of flow dynamics in complex geometry vessels is highly important in various biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT), as a functional extension of Optical Coherence Tomography (OCT), is an optic, non-contact, noninvasive technique able to achieve detailed analysis of the flow/vessel interactions. It allows simultaneous high resolution imaging (˜10 µm typical) of the morphology and composition of the vessel and determination of the flow velocity distribution along the measured cross-section. We applied DOCT system to image high-resolution one-dimensional and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds. The phantoms were built to mimic typical shapes of human blood vessels, enabling preliminary analysis of the interaction between flow dynamics and the (complex) geometry of the vessels and also to map the related velocity profiles at several inlet volume flow rates. Feasibility studies for quantitative observation of the turbulence of flows arising within the complex geometry vessels are discussed. In addition, DOCT technique was also applied for monitoring cerebral mouse blood flow in vivo. Two-dimensional DOCT images of complex flow velocity profiles in blood vessel phantoms and in vivo sub-cranial mouse blood flow velocities distributions are presented.

Bonesi, M.; Matcher, S.; Meglinski, I.

2010-06-01

263

Doppler optical coherence tomography in cardiovascular physiology  

Science.gov (United States)

The study of flow dynamics in complex geometry vessels is highly important in many biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT), as a functional extension of Optical Coherence Tomography (OCT), is an optic, non-contact, non-invasive technique able to achieve detailed analysis of the flow/vessel interactions. It allows simultaneous high resolution imaging (10 ?m typical) of the morphology and composition of the vessel and determination of the flow velocity distribution along the measured cross-section. We applied DOCT system to image high-resolution one-dimensional and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds. The phantoms were built to mimic typical shapes of human blood vessels, enabling preliminary analysis of the interaction between flow dynamics and the (complex) geometry of the vessels and also to map the related velocity profiles at several inlet volume flow rates. Feasibility studies for quantitative observation of the turbulence of flows arising within the complex geometry vessels are discussed. In addition, DOCT technique was also applied for monitoring cerebral mouse blood flow in vivo. Two-dimensional DOCT images of complex flow velocity profiles in blood vessel phantoms and in vivo sub-cranial mouse blood flow velocities distributions are presented.

Bonesi, M.; Meglinski, I.; Matcher, S.

2008-09-01

264

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

265

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

266

Doppler Findings in Intrapartum Fetal Distress  

Directory of Open Access Journals (Sweden)

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

Khatereh Tooba

2011-08-01

267

Lifetime measurements Doppler shift attenuation method  

International Nuclear Information System (INIS)

Gamma rays emitted from nuclei with a well defined initial velocity will exhibit a Doppler shift in the gamma-ray energy. If the excited nuclei slow down in some backing material there will be a continuous distribution of gamma ray energies. As the distribution (line shape) depends on the velocity loss in the stopping material and on the mean lifetime of the excited state it is possible to extract the lifetime value from the line shape measurements when stopping power of the backing material is known. At velocities V/c=0.5-1.5% the nuclei are mainly slown down be electrons. At lower velocities nuclear scattering is dominating. For velocities V/c>1.5% the electronic stopping power decreases again. This the region where mostly accurate measurements are available as well as a good phenomenological model. A way to escape the difficulties in the V/c=0.5-1.5% region is to use stopping material of which the stopping power is known experimentally. One can also use heavy ion beams on very light target nuclei. In the first heavy ion DSA experiments performed at Brookhaven beams of 18O, 19F, sup(32,34)S, sup(35,37C1 bombarded deuterium targets. The lifetime range (0.3-15 ps) obtained in these experiments is in overlape with recoil distance work. In Utrecht this technique is now being extended by observing outgoing particles in an annular detector positioned at 180deg. In coincidence with protons very clean gamma ray spectra were obtained at 0deg allowing to spectra were obtained at 0deg allowing to extract very accurate lifetimes. (S.B.)

268

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

269

Comparison between oscillometric- and Doppler-ABI in elderly individuals  

Directory of Open Access Journals (Sweden)

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

Takahashi I

2013-03-01

270

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

Science.gov (United States)

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.

Fung, Edward K.; Carson, Richard E.

2013-03-01

271

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 ratiard 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)

272

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

273

Color Doppler US in the acute scrotal disease  

International Nuclear Information System (INIS)

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

274

Differentiation of abdominal lymphadenoptahy with power doppler sonography  

International Nuclear Information System (INIS)

Purpose: Recent studies have reported high accuracy of power Doppler sonography (PDS) and color Doppler sonography (CDS) in the differentiation of benign and malignant peripheral superficial lymphadenopathy. This study was conducted to determine whether PDS can differentiate benign from malignant abdominal lymph nodes on the basis of defined vascular patterns. Materials and Methods: We retrospectively evaluated 88 color pictures of abdominal lymph nodes (39 benign lymph nodes, 24 malignant lymphomas, 25 lymph node metastasis) done in the power Doppler mode. The goal was to determine whether benign and malignant abdominal lymph nodes can be differentiated in power Doppler sonography on the basis of 9 defined vascular patterns. Results: Three vascular patterns showed a significantly (p < 0.05) higher appearance in malignant than in benign lymph nodes: aberrant vessel (specificity 87%), avascular focus (specificity 92%) and subcapsular vessel (specificity 100%). The vascular pattern hiliar vessel showed a significantly higher appearance in benign lymph nodes (specificity 87.8%). Conclusion: Three vascular patterns are detectable in power Doppler mode (avascular focus, aberrant vessel, subcapsular vessel) in abdominal lymph nodes, which are typical for malignant abdominal lymphadenopathy. The presence of one of these vascular patterns means with a high specificity (87 - 100%) that an abdominal lymphadenopathy is malignant. One vascular pattern (hiliar vessel) shows a signcular pattern (hiliar vessel) shows a significantly higher appearance in benign lymph nodes. (orig.)

275

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

276

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

277

Trans-skull ultrasonic Doppler system aided by fuzzy logic  

Science.gov (United States)

This paper describes a trans-skull ultrasonic Doppler system for measuring the blood flow direction in brain under skull. In this system, we use an ultrasonic array probe with the center frequency of 1.0 MHz. The system determines the fuzzy degree of blood flow by Doppler Effect, thereby it locates blood vessel. This Doppler Effect is examined by the center of gravity shift of the frequency magnitudes. In in-vitro experiment, a cow bone was employed as the skull, and three silicon tubes were done as blood vessels, and bubble in water as blood. We received the ultrasonic waves through a protein, the skull and silicon tubes in order. In the system, fuzzy degrees are determined with respect to the Doppler shift, amplitude of the waves and attenuation of the tissues. The fuzzy degrees of bone and blood direction are calculated by them. The experimental results showed that the system successfully visualized the skull and flow direction, compared with the location and flow direction of the phantom. Thus, it detected the flow direction by Doppler Effect under skull, and automatically extracted the region of skull and blood vessel.

Hata, Yutaka; Nakamura, Masato; Yagi, Naomi; Ishikawa, Tomomoto

2012-06-01

278

Intraluminal ultrasound intensity distribution and backscattered Doppler power.  

Science.gov (United States)

Ultrasound (US) incident obliquely on a cylindrical vessel is redistributed in space when the propagation path includes walls with acoustic impedance different from that of the surrounding media. We investigated this using low-density polyethylene (PE) as the vessel wall material. Both simulations and experiments were carried out. Direct hydrophone measurements of the acoustic field were made within a half section of the PE tube, and the distribution of backscattered Doppler power along a scan line was obtained using a range-Doppler instrument. Both simulation and hydrophone results demonstrate lateral shadow regions within the lumen. In every one of various Doppler flow experiments conducted, the backscattered Doppler power, compensated for on-axis transducer behaviour, increased with depth. Simulation results for an incident continuous-wave (CW) plane wave show that it tends to be focused by the curvature of the PE tube walls. The wall interactions are, however, angle-dependent and so the behaviour of a focused US beam depends on the beam as well as the walls. This study demonstrates alterations in the spatial distribution of US within a cylindrical vessel as a result of known vessel wall properties. It also provides evidence that local intensity variations within the lumen affect the relative Doppler power backscattered from small sample volumes. PMID:15588959

Thompson, Rosemary S; Bambi, Giacomo; Steel, Robin; Tortoli, Piero

2004-11-01

279

Doppler ultrasonographic imaging of obstruction of inferior vena cava  

International Nuclear Information System (INIS)

Budd-Chiari syndrome is a rare condition caused by hepatic venous outflow obstruction. Although liver biopsy and venography have been considered to be conclusive in the diagnosis of Budd-Chiari syndrome, those procedures involve a great deal of disecomfort and risk for the patient. As the recently developed Doppler ultrasonography is able to define the direction of blood flow and measure the blood flow velocity and volume in the portal vein, inferior vena cava(IVC) and hepatic vein, it can be used in the diagnosis of Budd-Chiari syndrome. We analyzed Doppler ultrasonographic findings in two patients with membraneous obstruction of the IVC, suspected from Doppler ultrasonographic findings and confirmed by venocavography. Doppler ultrasonography demonstrated reversed laminar flow on inspiration and no significant flow on expiration in the dilated IVC proximal to the stenosis and turbulent flow in the proximal portion of the stenosis. After balloon dilatation, the flow was changed and directed normally. These findings correlated very well with venocavographic findings. Our results suggest that Doppler ultrasonography is a simple, non-invasive and effective method for the initial evaluation of patients suspected of having obstruction of the IVC and the evaluation of therapeutic effect

280

Doppler effect in the oscillator radiation process in the medium  

International Nuclear Information System (INIS)

The purpose of this paper is to investigate the radiation process of the charged particle passing through an external periodic field in a dispersive medium. In the optical range of spectrum we will consider two cases: first, the source has not eigenfrequency, and second, the source has eigenfrequency. In the first case, when the Cherenkov radiation occurs, the non-zero eigenfrequency produces a paradox for Doppler effect. It is shown that the absence of the eigenfrequency solves the paradox known in the literature. The question whether the process is normal (i.e. hard photons are being radiated under the small angles) or anomalous depends on the law of the medium dispersion. When the source has an eigenfrequency the Doppler effects can be either normal or anomalous. In the X-ray range of the oscillator radiation spectrum we have two photons radiated under the same angle-soft and hard. In this case the radiation obeys to so-called complicated Doppler effect, i.e. in the soft photon region we have anomalous Doppler effect and in the hard photon region we have normal Doppler effect.

281

Doppler processing, waveform design and performance measures for some pulsed Doppler and MTD-radars. I  

Science.gov (United States)

Shortcomings of the classical moving target indicator (MTI) radar followed by a moving window detector (automatic target detector) are examined, and fundamental algorithms for an improved signal processing are considered. The considered investigation is concerned with the revision of classical performance measures such as improvement factor and subclutter visibility. Attention is given to an n-pulse moving target detector (MTD) subsystem for a frequency diversity radar. Aspects of Doppler processing, waveform design, and parameter extraction are investigated, taking into account the burst waveform and batch processing, the filter bank processor, advantages of filter bank processing, the number of filters required and filter implementation, the number of bursts per beamwidth and azimuth accuracy, and the detailed design of burst waveform.

Ludloff, A.; Fuechter, N.; Hagedorn, F.; Minker, M.; Rohling, H.

282

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

283

Detection and Characterization of Extrasolar Planets through Doppler Spectroscopy  

CERN Document Server

Over 300 extrasolar planets have been found since 1992, showing that planetary systems are common and exhibit an outstanding variety of characteristics. As the number of detections grows and as models of planet formation progress to account for the existence of these new worlds, statistical studies and confrontations of observation with theory allow to progressively unravel the key processes underlying planet formation. In this chapter we review the dominant contribution of Doppler spectroscopy to the present discoveries and to our general understanding of planetary systems. We also emphasize the synergy of Doppler spectroscopy and transit photometry in characterizing the physical properties of transiting extrasolar planets. As we will see, Doppler spectroscopy has not reached its limits yet and it will undoubtly play a leading role in the detection and characterization of the first Earth-mass planets.

Eggenberger, A

2009-01-01

284

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)

285

Doppler ultrasonography in lower extremity peripheral arterial disease.  

Science.gov (United States)

Systemic atherosclerosis is a condition which progresses with age, decreases quality of life, and life expectancy. Lower extremity peripheral arterial disease (PAD) is a common manifestation of systemic atherosclerosis in the elderly. These individuals have a 2 to 4 fold higher risk of coronary heart disease and stroke. In addition, systemic atherosclerosis causes overall functional disability including restricted lower extremity movements. When used alone for diagnostic purposes, claudication is an unreliable sign of PAD in all age groups especially the elderly. Moreover, claudication is difficult to define due to the advancing age and degenerative changes in lumbar and peripheral joints. Doppler ultrasonography (US) is an easily available and noninvasive means of arterial visualization in the lower extremities. In this review, supporting evidence for the use of Doppler US in the diagnosis of PAD will be discussed. Past and present recommendations regarding Doppler US in the current PAD guidelines will be overviewed. PMID:23703564

Verim, Samet; Ta?ç?, Ilker

2013-04-01

286

Imaging nanoparticle flow using magneto-motive optical Doppler tomography  

International Nuclear Information System (INIS)

We introduce a novel approach for imaging solutions of superparamagnetic iron oxide (SPIO) nanoparticles using magneto-motive optical Doppler tomography (MM-ODT). MM-ODT combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect nanoparticles flowing through a microfluidic channel. A solenoid with a cone-shaped ferrite core extensively increased the magnetic field strength (Bmax = 1 T, ?B2=220T2m-1) at the tip of the core and also focused the magnetic field in microfluidic channels containing nanoparticle solutions. Nanoparticle contrast was demonstrated in a microfluidic channel filled with an SPIO solution by imaging the Doppler frequency shift which was observed independently of the nanoparticle flow rate and direction. Results suggest that MM-ODT may be applied to image Doppler shift of SPIO nanoparticles in microfluidic flows with high contrast

287

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

288

Assessment of endometrial receptivity by Color Doppler and ultrasound imaging  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: Color Doppler sonography is a new method used to investigate changes during the menstrual cycle in infertile women. The objective of this study was to investigate the correlation of uterine and endomterial-subendomterial blood flow in infertile women using ultrasound and color Doppler sonography. Material and methods: A prospective clinical study included 65 infertile women divided into three groups. Transvaginal ultrasound examination was performed on days XI, XIV and XX. All results were statistically analyzed. We investigated the correlation between cycles, pregnancy outcome and distribution of endomterial-subendomterial blood flow, as well as uterine arterial blood flow. Results and conclusion: Endomterial-subendometerial blood flow distribution pattern assessed by transvaginal color Doppler, as well as good flow in uterine vessels, are necessery for good pregnancy rates. Thin endomterium, undetectable subendomterial blood flow and higher uterine arterial resistance, were associated with low pregnancy rate and poor outcome.

Lili? Vekoslav

2007-01-01

289

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

290

Holographic laser Doppler imaging of microvascular blood flow  

CERN Document Server

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

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

2014-01-01

291

Development of Dual Beam High Speed Doppler OFD  

International Nuclear Information System (INIS)

This paper describes development of a high speed Doppler OFDI system for non-invasive vascular imaging. Doppler OFDI (optical frequency domain imaging) is one of the phase-resolved second generation OCT (optical coherence tomography) techniques for high resolution imaging of moving elements in biological tissues. To achieve a phase-resolved imaging, two temporally separated measurements are required. In a conventional Doppler OCT, a pair of massively oversampled successive A-lines is used to minimize de-correlation noise at the expense of significant imaging speed reduction. To minimize a de-correlation noise between targeted two measurements without suffering from significant imaging speed reduction, several methods have been developed such as an optimized scanning pattern and polarization multiplexed dual beam scanning. This research represent novel imaging technique using frequency multiplexed dual beam illumination to measure exactly same position with aimed time interval. Developed system has been verified using a tissue phantom and mouse vessel imaging.

292

Development of Dual Beam High Speed Doppler OFD  

Energy Technology Data Exchange (ETDEWEB)

This paper describes development of a high speed Doppler OFDI system for non-invasive vascular imaging. Doppler OFDI (optical frequency domain imaging) is one of the phase-resolved second generation OCT (optical coherence tomography) techniques for high resolution imaging of moving elements in biological tissues. To achieve a phase-resolved imaging, two temporally separated measurements are required. In a conventional Doppler OCT, a pair of massively oversampled successive A-lines is used to minimize de-correlation noise at the expense of significant imaging speed reduction. To minimize a de-correlation noise between targeted two measurements without suffering from significant imaging speed reduction, several methods have been developed such as an optimized scanning pattern and polarization multiplexed dual beam scanning. This research represent novel imaging technique using frequency multiplexed dual beam illumination to measure exactly same position with aimed time interval. Developed system has been verified using a tissue phantom and mouse vessel imaging.

Park, Tae Jin; Oh, Wang Yuhl [Dept. of Mechanical Engineering, Korea Advance Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Sun Hee [Korea Railroad Research Institute, Uiwang (Korea, Republic of)

2013-06-15

293

Three-dimensional laser cooling at the Doppler limit  

CERN Document Server

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

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

2014-01-01

294

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

295

Doppler Tomography in Cataclysmic Variables: an historical perspective  

CERN Document Server

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

Echevarria, J

2012-01-01

296

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

297

The Doppler paradigm and the APEX-EPOS-ORANGE quandary  

CERN Document Server

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

298

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/1 geometries select narrower slices of a Doppler broadened line than spherically inclusive (APEX and EPOS/2 -like) apparats. 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/2's coincident pair distributions must be statistically superior to those of EPOS/1 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. (author)

299

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

Science.gov (United States)

... false Doppler Radar and Inertial Navigation System (INS): Request...121—Doppler Radar and Inertial Navigation System (INS): Request...to use a Doppler Radar or Inertial Navigation System must submit a...

2010-01-01

300

Doppler and Reflectivity Measurements at Two Closely-Spaced Frequencies  

Science.gov (United States)

Spaceborne and airborne radars are limited with a respect to the mass and size of the instrument and the power available to operate it. As a consequence, dual-wavelength radars that require separate antennas and power amplifiers are expensive and often impractical. However, if the frequency difference can be reduced so that a single antenna and the same radio-frequency subsystem can be used for both frequencies, dual- wavelength Doppler measurements can be made with a radar of about the same size and mass as its single-frequency counterpart. In the first part of the paper we present calculations of the reflectivity factor differences as functions of the center frequency from 10 to 35 GHz and for frequency differences between -10% and 10% of the center frequency. The results indicate that differential-frequency operation at Ka-band frequencies (26.5 - 40 GHz) provides relatively strong differential signals if the frequencies can be separated by at least 5%. Unlike lower frequency operation, the differential signals at Ka-band (both reflectivity and Doppler) are directly related to the median mass diameter. An important feature of the differential mean Doppler is that it depends only on the drop-size dependent part of the radial velocity. In principle, the mean and mean differential Doppler data from a nadir-looking platform can be used to infer vertical air motion and characteristics of the particle size distribution. To test the instrument concept, the ER-2 Doppler radar was modified for differential frequency operation. Measurements by the modified radar, operating at frequencies of 9.1 GHz and 10 GHz, were made using an 8 degree zenith-pointing offset parabolic antenna. Simultaneous data were taken with an optical rain gauge and an impact disdrometer. Measured and DSD-estimated values of the differential dBZ mean Doppler are presented.

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

2001-01-01

301

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

302

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

303

Tracking airborne targets occasionally hidden in the blind Doppler  

Science.gov (United States)

This paper describes an application of sequential Monte Carlo estimation (particle filtering) to the problem of tracking targets occasionally hidden in the blind Doppler zones of a radar. A particle filter which incorporates the prior knowledge of the blind Doppler zone limits has been designed. The simulation results suggest significant improvement in track continuity over the standard Extended Kalman filter. As an operationally viable solution a hybrid tracker is envisaged which can switch between the EKF (with possible built-in data association logic) and the particle filter, depending on the tracking conditions.

Gordon, Neil J.; Ristic, Branko

2001-11-01

304

Spectral fine structure effects on material and doppler reactivity worth  

International Nuclear Information System (INIS)

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

305

Large Doppler Compensation for Mobile OFDM Based Underwater Acoustic Communication  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, large Doppler compensation for Orthogonal Frequency Division Multiplexing (OFDM suitable for mobile underwater acoustic communication is proposed. The scheme is applicable to underwater acoustic communication between rapidly moving platforms. Considering the structural characteristics of OFDM symbols, re-sampling and time-frequency differential code mapping are used to realize the broadband and narrowband Doppler compensation. The experimental results prove the feasibility of the proposed scheme. In addition, the error performance of this scheme in different Signal-to-Noise Ratio (SNR and different relative speed is given.

Zhengrong Pan

2013-01-01

306

Doppler echocardiographic parameters of evaluation of left ventricular systolic function.  

Science.gov (United States)

The authors suggest a new method using Doppler echocardiography for the evaluation of cardiac performance. Doppler echocardiography permits the calculation of left ventricular (LV) ejection force (according to Newton's second law of motion). The ejection force was calculated in 36 patients with heart failure subgrouped into 3 groups based on ejection fraction (EF) (> 60%; 41-60%; < 40%) compared to 11 normal subjects. The LV ejection force showed a good linear correlation with LV ejection fraction (r = 0.86). Data of the study suggest that the LV ejection force is a valuable and accurate index for the assessment of cardiac performance, especially in early stages of disease. PMID:8130754

Dr?gulescu, S I; Ro?u, D; Abazid, J; Ionac, A

1993-01-01

307

Optical Doppler tomography based on a field programmable gate array  

DEFF Research Database (Denmark)

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

Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup

2008-01-01

308

Doppler-broadening of positron annihilation in a biological environment  

International Nuclear Information System (INIS)

The aim of this study was to investigate the Doppler effect of the 511 keV ? peak from positron annihilation in biological matter: The broadening of the annihilation peak is due to positron annihilation with electrons that have high momentum. In aqueous solutions annihilation depends on the temperature and it is linked positronium formation. Measurements in vivo, on human brain, were taken during the diagnosis of positron emission tomography (PET) on healthy patients by injecting them with the beta emitter of short lifetime 18F. The Doppler-broadening in biological tissues rich in water content decreased significantly compared to biological solutions and water

309

Deconvolution of infrared spectra beyond the Doppler limit  

Science.gov (United States)

It is shown that the deconvolution method of Van Cittert can be used reliably to enhance the effective spectral resolution by a factor of about 3 with data that exhibit a high SNR and in which base line variations have been eliminated. Deconvolution of a Doppler-limited spectrum of C6H6 measured on a difference-frequency laser system yielded linewidths of about 1.2 x 10 to the -3 per cm (compared with the Doppler width of 3.6 x 10 to the -3 per cm at 203 K). Extensive reliability tests of the deconvolution technique have been performed.

Pilva, J.; Pine, A. S.; Willson, P. D.

1980-06-01

310

Transvaginal color Doppler sonography of ovarian masses with pathological correlation.  

Science.gov (United States)

This report describes the correlation of pathological findings with transvaginal color Doppler sonography performed preoperatively on 26 ovarian masses. The pulsatility indices of benign lesions (1.9 +/- 0.7) were higher than those of malignant ones (0.7 +/- 0.2) (p = 0.03). Low pulsatility indices (teratoma, one cystadenoma containing a dermoid cyst, one endometrioma), causing an overlap between the pulsatility indices of some benign and malignant masses. There appears to be significant potential for discrimination between benign and malignant ovarian masses with transvaginal color Doppler sonography. PMID:12797059

Fleischer, A C; Rogers, W H; Rao, B K; Kepple, D M; Jones, H W

1991-07-01

311

Special Theory of Relativity through the Doppler Effect  

CERN Document Server

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

Moriconi, M

2006-01-01

312

Special theory of relativity through the Doppler effect  

Energy Technology Data Exchange (ETDEWEB)

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

Moriconi, M [Departamento de Fisica, Universidade Federal Fluminense, Av. Litoranea s/n, Boa Viagem-CEP 24210-340, Niteroi, Rio de Janeiro (Brazil)

2006-11-01

313

Special theory of relativity through the Doppler effect  

International Nuclear Information System (INIS)

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

314

Post stress tissue Doppler imaging can identify false positive exercise electrocardiogram.  

Science.gov (United States)

Post stress tissue Doppler imaging can diagnose false positive response on exercise electrocardiography. Tissue Doppler imaging thus provides additional useful parameter to increase specificity of stress testing for evaluation of coronary artery disease. PMID:25327038

Mittal, S R

2014-04-01

315

Narrow-Band Searches for Gravitational Radiation with Spacecraft Doppler Tracking  

Science.gov (United States)

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

Tinto, M.; Armstrong, J. W.

1997-01-01

316

Accuracy of Doppler Echocardiography in the Hemodynamic Assessment of Pulmonary Hypertension  

OpenAIRE

Rationale: Transthoracic Doppler echocardiography is recommended for screening for the presence of pulmonary hypertension (PH). However, some recent studies have suggested that Doppler echocardiographic pulmonary artery pressure estimates may frequently be inaccurate.

Fisher, Micah R.; Forfia, Paul R.; Chamera, Elzbieta; Housten-harris, Traci; Champion, Hunter C.; Girgis, Reda E.; Corretti, Mary C.; Hassoun, Paul M.

2009-01-01

317

Photoplethysmography can replace hand-held Doppler in the measurement of ankle/brachial indices.  

OpenAIRE

Ankle/brachial pressure index (ABPI) using hand-held Doppler and sphygmomanometer is a standard assessment for patients with peripheral arterial occlusive disease (PAOD). Good Doppler technique is difficult to master and so we investigated replacing Doppler with photoplethysmography (PPG). Two investigators examined 52 legs in 32 vascular patients. Both used standard sphygmomanometer cuff occlusion. Restoration of flow was detected by either an 8 MHz Doppler ultrasound probe or a PPG transmit...

Whiteley, M. S.; Fox, A. D.; Horrocks, M.

1998-01-01

318

Swept-source based, single-shot, multi-detectable velocity range Doppler optical coherence tomography  

OpenAIRE

Phase-Resolved Doppler Optical Coherence Tomography (PR-DOCT) allows visualization and characterization of the location, direction, velocity, and profile of flow activity embedded in a static sample structure. The detectable Velocity Dynamic Range (VDR) of each particular PR-DOCT system is governed by a detectable Doppler phase shift, a flow angle, and an acquisition time interval used to determine the Doppler phase shift. In general, the lower boundary of the detectable Doppler phase shift i...

Meemon, Panomsak; Rolland, Jannick P.

2010-01-01

319

A case report of traumatic intrahepatic artery aneurysm: Diagnosis with color Doppler imaging and transarterial embolization  

International Nuclear Information System (INIS)

We experienced a case of intrahepatic artery aneurysm after blunt abdominal trauma which was diagnosed by color Doppler imaging and hepatic arteriography. Color Doppler imaging showed hypoechoic lesion with thick irregular walls and complex arterial flow. Successful transcatheter embolization with occluding spring coil was done. Follow up color Doppler imaging showed no color flow signal within the aneurysm, indicating occlusion of the aneurysm. Color Doppler imaging was useful for diagnosis of hepatic aneurysm and follow-up evaluation of transcatheter embolization

320

A case report of traumatic intrahepatic artery aneurysm: Diagnosis with color Doppler imaging and transarterial embolization  

Energy Technology Data Exchange (ETDEWEB)

We experienced a case of intrahepatic artery aneurysm after blunt abdominal trauma which was diagnosed by color Doppler imaging and hepatic arteriography. Color Doppler imaging showed hypoechoic lesion with thick irregular walls and complex arterial flow. Successful transcatheter embolization with occluding spring coil was done. Follow up color Doppler imaging showed no color flow signal within the aneurysm, indicating occlusion of the aneurysm. Color Doppler imaging was useful for diagnosis of hepatic aneurysm and follow-up evaluation of transcatheter embolization

Kim, Jaae Kyu; Yoon, Woong; Kim, Hyun Ju; Kang, Heoung Keun; Chung, Hyon De [Chonnam National University College of Medicine, Gwangju (Korea, Republic of)

1994-12-15

321

Phase Doppler anemometry for balancing and modelling of multiphase flow. Phasen-Doppler-Anemometrie zum Bilanzieren und Modellieren mehrphasiger Stroemungen  

Energy Technology Data Exchange (ETDEWEB)

Diffraction, refraction, and reflection are components of the light scattered on interaction with dispersed systems. They lead to differing measurable phenomena and are utilised for the characterisation of particle properties in multiphase flow. The property of greatest interest is the particle size. Contact- and reaction-free optical laser measuring methods suitable for in-line measurements, such as phase Doppler anemometry, utilise light scattered by the particles in order to determine their size and velocity, and also to some extent for the determination of other dispersion-related or kinetic particle properties. This is illustrated for the case of phase Doppler anemometry. (orig.)

Bauckhage, K. (Bremen Univ., Verfahrenstechnik, Fachbereich Produktionstechnik (Germany))

1993-08-01

322

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

323

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

324

Multi-sensor Doppler radar for machine tool collision detection  

Science.gov (United States)

Machine damage due to tool collisions is a widespread issue in milling production. These collisions are typically caused by human errors. A solution for this problem is proposed based on a low-complexity 24 GHz continuous wave (CW) radar system. The developed monitoring system is able to detect moving objects by evaluating the Doppler shift. It combines incoherent information from several spatially distributed Doppler sensors and estimates the distance between an object and the sensors. The specially designed compact prototype contains up to five radar sensor modules and amplifiers yet fits into the limited available space. In this first approach we concentrate on the Doppler-based positioning of a single moving target. The recorded signals are preprocessed in order to remove noise and interference from the machinery hall. We conducted and processed system measurements with this prototype. The Doppler frequency estimation and the object position obtained after signal conditioning and processing with the developed algorithm were in good agreement with the reference coordinates provided by the machine's control unit.

Wächter, T. J.; Siart, U.; Eibert, T. F.; Bonerz, S.

2014-11-01

325

Color Doppler in the Assessment of Uteroplacental Circulation Insufficiency  

Directory of Open Access Journals (Sweden)

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

Ahmad Soltani Shirazi

2010-05-01

326

Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

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

Erskine, D J; Edelstein, J; Lloyd, J; Muirhead, P

2006-05-04

327

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

328

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

329

Planar Doppler velocimetry using a Mach-Zehnder interferometric filter  

International Nuclear Information System (INIS)

A planar Doppler velocimetry system to measure flow velocity fields is described. The technique uses a Mach-Zehnder interferometric filter to convert Doppler frequency shifts into intensity variations. The free spectral range of the filter can be selected by adjusting the optical path difference of the interferometer. This allows the velocity measurement range, sensitivity and resolution to be varied. An experimental arrangement is described that incorporates a phase-locking system designed to stabilise the interferometric filter. Two methods to process the interference fringe images are presented; the first uses the shift of the fringe pattern to determine the Doppler shift along profiles. The second provides a full-field measurement of the Doppler shift by determining the phase at each pixel in the images. Results are presented here for measurements of velocity fields on a rotating disc with maximum velocities, at the edge, of ±70m/s. Measurements on a seeded air jet with a nozzle diameter of 20mm and an exit velocity of ?85m/s are also presented

330

Formulation of relativistic Doppler-broadened absorption line profile  

Science.gov (United States)

The relativistic Doppler-broadened profile of an absorption line due to the thermal motion of light-absorbing particles is formulated. The obtained profile of an absorption line is asymmetrically broadened with more weight in the redshift wing than in the blueshift wing. Moreover, the peak frequency of the profile of an absorption line evinces red-shifting with increasing temperature.

Huang, Young-Sea

2012-01-01

331

Color Doppler sonographic findings in focal spleen lesions  

International Nuclear Information System (INIS)

Since focal lesions of the spleen are rare (0.2%), there is little data concerning color Doppler images of focal lesions of the spleen. Objective: The aim of this study is to describe the color Doppler images of 98 etiologically proved focal spleen lesions. Methods: In about 110,000 consecutive abdominal ultrasound examinations, which included the spleen, 600 patients with focal lesions of the spleen were identified. In 98 of these patients a color Doppler scan of the lesion was performed and documented. These scans were analysed retrospectively and classified as avascular, hypovascular, isovascular, hypervascular and arterio-venous 'high flow', using the surrounding spleen tissue as an in vivo reference. Results: In color Doppler sonography (CDS) 68.4% (n = 67) of the focal spleen lesions showed no flow. 15.3% (n = 15) appeared hypovascular, 8.2% (n = 8) isovascular, 5.1% (n = 5) hypervascular, and in 3.1% (n = 3) an arterio-venous 'high flow'-pattern was found. Conclusions: In CDS about two thirds (68%) of focal spleen lesions appear to be avascular. Except from diagnosis of intra-splenic pseudo-aneurysm, the practical utility of CDS in diagnosing focal spleen lesions has to be estimated as low

332

Hypercholesterolemia and Myocardial function evaluated via Tissue Doppler Imaging  

OpenAIRE

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...

Kotaru Pavan; Vedre Ameeth; Pelosi Augusta; Rubinstein Jack; Abela George S

2009-01-01

333

Pränatale Diagnostik bei intrauteriner Wachstumsrestriktion mittels Tissue Doppler Imaging Echokardiographie  

OpenAIRE

Tissue Doppler Imaging (TDI) ermöglicht eine direkte quantitative Analyse der fetalen Myokardfunktion. In der Studie wurden kardiale TDI-Messungen bei IUGR-Feten (intrauterine growth restriction, intrauterine Wachstumsrestriktion, Schätzgewicht < 5. Perzentile) im Vergleich zu gesunden Feten durchgefu?hrt. Bei den IUGR-Feten fanden sich eine niedrigere maximale systolische Velocity (Vmax) und ein höherer Myocardial Performance Index (MPI') in beiden Ventrikeln, ein...

Braun, M. C.

2014-01-01

334

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

OpenAIRE

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 ...

Thomas George

2004-01-01

335

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, D.M.

1984-04-12

336

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

337

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

338

Methods to evaluate the sample volume of pulsed Doppler systems.  

Science.gov (United States)

The spatial resolution of a pulsed Doppler system heavily depends on both the characteristics of the ultrasound transducer and the processing circuitry. The local characteristics of the ultrasound beam give the lateral sample function while the way the signals are processed affects the axial shape of the sample volume. A simple way to explore the size of the sample volume is the employment of a running string target. However, the detected Doppler signals will be the sum of all the Doppler signals returned by the string along its course through the sample volume. Therefore, it will be complicated to separate the axial and lateral contribution to the actual size of the sample volume. A scanning system capable of visualizing the cross-sectional distribution of the ultrasound intensity allows the assessment of the sample sensitivity in lateral direction. A single vibrating point target enables the exploration of both the axial and lateral sampling function. The latter approach is especially suited to evaluate routinely the spatial performance of pulsed Doppler systems in clinical practice. PMID:6390902

Hoeks, A P; Ruissen, C J; Hick, P; Reneman, R S

1984-01-01

339

Doppler reflectometry. Measuring the propagation velocity of density perturbations  

International Nuclear Information System (INIS)

Doppler reflectometry is a radar measurement where a microwave signal probes the plasma with a line of sight which is non-perpendicular with respect to the reflecting layer. According to the Bragg condition the diagnostic selects density perturbations with finite wavevector Ksub(perpendicular) in the reflecting layer. From the Doppler shift of the returning microwave signal the propagation velocity ?sub(perpendicular) perpendicular to the magnetic field can be obtained whereas the signal intensity contains information about the perturbation amplitude. The diagnostic capability of Doppler reflectometry is discusses and results from the W7-AS stellarator are presented. During stationary phases the measured values ?sub(perpendicular)(r) and their radial dependence are in good agreement with the E x B velocity of the plasma obtained from passive spectroscopy. Transient states of the plasma can be followed with a temporal resolution of less than 50 ?s. Therefore Doppler reflectometry allows one to measure the interdependence of sheared flow and turbulence on that timescale. (author)

340

Color Doppler Ultrasonography in Evaluation of the Postoperative Penis  

Directory of Open Access Journals (Sweden)

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

M. Ghafouri

2005-08-01

341

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 fphology, 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

342

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

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

1144-11-01

343

Valoración por ultrasonografía Doppler en medicina materno-fetal / Doppler ultrasonography assessment in maternal-foetal medicine  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Introducción y objetivo: desde la década del 80, las técnicas de ecografía Doppler han permitido en-tender de manera más precisa la hemodinamia fetoplacentaria y sus variantes fisiológicas. Igualmente han ayudado a reconocer los cambios patológicos generados en el feto ante diferentes tipos de lesió [...] n, permitiendo actuar de forma oportuna y así impactar de manera importante en la disminución de los índices de morbilidad y mortalidad neonatal. El objetivo de la siguiente revisión es ofrecer al médico una visión clara y concisa de las utilidades de la ecografía Doppler, lo cual le permitirá aplicarla en su práctica diaria. Métodos: se realizó una búsqueda bibliográfica en diferentes bases de datos electrónicas (Pubmed, Ovid, Elsevier, Interscience, Cochrane) y libros de texto impresos, tratando de encontrar la mejor evidencia respecto a las utilidades de la ecografía Doppler. Hallazgos de la revisión: la ecografía Doppler se ha convertido en un instrumento diagnóstico de gran aplicación en el campo de la medicina materno-fetal. Hoy en día es clave para el diagnóstico y seguimiento de fetos con anemia o con restricción del crecimiento fetal, tamizaje de aneuploidías realizado en el primer trimestre del embarazo, estudio de morfología fetal, diagnóstico de accretismo placentario, detección temprana de infección fetal y tamizaje para patologías derivadas de insuficiencia útero-placentaria (retardo del crecimiento intrauterino [RCIU] y preeclampsia) así como resultado perinatal adverso. Conclusión: la ecografía Doppler es una herramienta diagnóstica que ha revolucionado la perinatología, ya que ha permitido disminuir de manera importante los procedimientos invasivos en el feto, así como conocer de manera clara los cambios fisiológicos que se dan en la unidad feto-placentaria, entre otras utilidades. Abstract in english Introduction: Doppler ultrasound techniques (available since the 1980s) have allowed a more precise understanding of foetal-placental haemodynamics and their physiological variants. They have also helped in recognising pathological changes produced in the foetus by different types of injury, allowin [...] g more precise action to be taken and decreasing neonatal morbidity and mortality. This article is aimed at offering a comprehensive review of Doppler technology in perinatal medicine and pointing out its practical usefulness in current obstetric practice. Methods: electronic databases (PubMed, Ovid, Elsevier, InterScience, Cochrane) and text books were reviewed to obtain the best evidence regarding using Doppler technology in perinatal medicine. Results: Doppler ultrasonography has become a diagnostic tool having wide application in the field of maternal-foetal medicine. It is currently the key for diagnosing and managing foetuses affected by anaemia or foetal growth restriction (FGR), chromosomal abnormality screening during the first three months of pregnancy, studying foetal morphology, diagnosing placenta accreta, the early detection of foetal infection and screening for utero-placental insufficiency-derived pathologies (FGR and preeclampsia) and adverse perinatal outcomes. Conclusion: Doppler ultrasonography used as a diagnostic tool has changed perinatal practice, allowing more precise handling of invasive foetal procedures (as well as reducing them) and giving us a better understanding of the physiological changes occurring at foetal-placental level.

Pablo Andrés, Victoria-Gómez.

2006-09-01

344

Valoración por ultrasonografía Doppler en medicina materno-fetal Doppler ultrasonography assessment in maternal-foetal medicine  

Directory of Open Access Journals (Sweden)

Full Text Available Introducción y objetivo: desde la década del 80, las técnicas de ecografía Doppler han permitido en-tender de manera más precisa la hemodinamia fetoplacentaria y sus variantes fisiológicas. Igualmente han ayudado a reconocer los cambios patológicos generados en el feto ante diferentes tipos de lesión, permitiendo actuar de forma oportuna y así impactar de manera importante en la disminución de los índices de morbilidad y mortalidad neonatal. El objetivo de la siguiente revisión es ofrecer al médico una visión clara y concisa de las utilidades de la ecografía Doppler, lo cual le permitirá aplicarla en su práctica diaria. Métodos: se realizó una búsqueda bibliográfica en diferentes bases de datos electrónicas (Pubmed, Ovid, Elsevier, Interscience, Cochrane y libros de texto impresos, tratando de encontrar la mejor evidencia respecto a las utilidades de la ecografía Doppler. Hallazgos de la revisión: la ecografía Doppler se ha convertido en un instrumento diagnóstico de gran aplicación en el campo de la medicina materno-fetal. Hoy en día es clave para el diagnóstico y seguimiento de fetos con anemia o con restricción del crecimiento fetal, tamizaje de aneuploidías realizado en el primer trimestre del embarazo, estudio de morfología fetal, diagnóstico de accretismo placentario, detección temprana de infección fetal y tamizaje para patologías derivadas de insuficiencia útero-placentaria (retardo del crecimiento intrauterino [RCIU] y preeclampsia así como resultado perinatal adverso. Conclusión: la ecografía Doppler es una herramienta diagnóstica que ha revolucionado la perinatología, ya que ha permitido disminuir de manera importante los procedimientos invasivos en el feto, así como conocer de manera clara los cambios fisiológicos que se dan en la unidad feto-placentaria, entre otras utilidades.Introduction: Doppler ultrasound techniques (available since the 1980s have allowed a more precise understanding of foetal-placental haemodynamics and their physiological variants. They have also helped in recognising pathological changes produced in the foetus by different types of injury, allowing more precise action to be taken and decreasing neonatal morbidity and mortality. This article is aimed at offering a comprehensive review of Doppler technology in perinatal medicine and pointing out its practical usefulness in current obstetric practice. Methods: electronic databases (PubMed, Ovid, Elsevier, InterScience, Cochrane and text books were reviewed to obtain the best evidence regarding using Doppler technology in perinatal medicine. Results: Doppler ultrasonography has become a diagnostic tool having wide application in the field of maternal-foetal medicine. It is currently the key for diagnosing and managing foetuses affected by anaemia or foetal growth restriction (FGR, chromosomal abnormality screening during the first three months of pregnancy, studying foetal morphology, diagnosing placenta accreta, the early detection of foetal infection and screening for utero-placental insufficiency-derived pathologies (FGR and preeclampsia and adverse perinatal outcomes. Conclusion: Doppler ultrasonography used as a diagnostic tool has changed perinatal practice, allowing more precise handling of invasive foetal procedures (as well as reducing them and giving us a better understanding of the physiological changes occurring at foetal-placental level.

Pablo Andrés Victoria-Gómez

2006-09-01

345

Micro-Doppler analysis of multiple frequency continuous wave radar signatures  

Science.gov (United States)

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

Anderson, Michael G.; Rogers, Robert L.

2007-04-01

346

Measurement of doppler effect up to 2000degC at FCA  

International Nuclear Information System (INIS)

For the improvement of the Doppler effect calculation accuracy in high temperature range, new experimental devices were developed to measure Doppler effect up to 2000degC and measurements were carried out at Fast Critical Assembly of JAERI. For the measurements, two methods were used: the one is a sample reactivity measurement and the other is a foil activation measurement with laser heating. In the analyzing the experimental data, a new cell calculation code of ultra-fine groups, PEACO-X, was used to generate effective cross sections of the Doppler sample, which took into account the resonance overlapping effect between the 238U of the Doppler sample and the tungsten structural material of experimental devices. The calculation of the Doppler effect underestimated the measured Doppler reactivity worths for the sample reactivity method, while it showed a good agreement with the measured Doppler ratio for the foil activation method. (author)

347

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 distribution. Doppler velocities from a zenith-pointing radar represent the sum of the mean reflectivity-weighted hydrometeor fallspeed and the vertical air motion. Dual-parameter rain estimation methods using the Doppler velocity, require that the latter can be removed, or is negligible. Atlas et al. (1972) derived relations between Doppler velocity, reflectivity, and rain rate assuming an exponential size distribution for rain. Ulbrich (1994) expanded on this work by deriving the relation between the Doppler velocity and the reflectivity assuming a Gamma size distribution. This distribution provides a more realistic representation of the small rain drops. To get accurate information on raindrop size distributions with the above method, the air motions must be removed from the observed Doppler velocities

Heymsfield, Gerald M.; Tian, L.; Geerts, Bart

1999-01-01

348

Continuous-wave Doppler echocardiographic assessment of severity of calcific aortic stenosis: a simultaneous Doppler-catheter correlative study in 100 adult patients.  

Science.gov (United States)

Studies of the correlation of aortic valve gradient determined by continuous-wave Doppler echocardiography and that determined at catheterization have, to date, involved young patients and nonsimultaneous measurements. We therefore obtained simultaneous Doppler echocardiographic and catheter measurements of pressure gradient in 100 consecutive adults (mean age 69, range 50 to 89 years). In 63 patients pressure measurements were obtained with dual-catheter techniques and in 37 they were obtained by withdrawal of the catheter from the left ventricle to the ascending aorta. Forty-six of these patients also underwent an outpatient Doppler study 7 days or less before catheterization. The simultaneous pressure waveforms and Doppler spectral velocity profiles were digitized at 10 msec intervals and maximum, mean, and instantaneous gradients (mm Hg) were derived for each. The correlation between the Doppler-determined gradient and the simultaneously measured maximum catheter gradient was r = .92 (SEE = 15 mm Hg), that between the Doppler-determined and mean catheter gradient was r = .93 (SEE = 10 mm Hg), and that between the Doppler and peak-to-peak catheter gradient was r = .91 (SEE = 14). The correlation between the nonsimultaneously Doppler-determined gradient and the maximum gradient measured by catheter was not as strong (r = .79, SEE = 24). The continuous-wave Doppler echocardiographic velocity profile represents the instantaneous transaortic pressure gradient throughout the cardiac cycle. The best correlation with continuous-wave Doppler-determined gradient was obtained with maximum and mean gradients measured by catheter. Continuous-wave Doppler echocardiography can be used to reliably predict the pressure gradient in adults with calcific aortic stenosis. PMID:3995710

Currie, P J; Seward, J B; Reeder, G S; Vlietstra, R E; Bresnahan, D R; Bresnahan, J F; Smith, H C; Hagler, D J; Tajik, A J

1985-06-01

349

Photoacoustic Doppler measurement of flow using tone burst excitation.  

Science.gov (United States)

In this paper a novel technique for flow measurement which is based on the photoacoustic (PA) Doppler effect is described. A significant feature of the proposed approach is that it can be implemented using tone burst optical excitation thus enabling simultaneous measurement of both velocity and position. The technique, which is based on external modulation and heterodyne detection, was experimentally demonstrated by measurement of the flow of a suspension of carbon particles in a silicon tube and successfully determined the particles mean velocity up to values of 130 mm/sec, which is about 10 times higher than previously reported PA Doppler set-ups. In the theoretical part a rigorous derivation of the PA response of a flowing medium is described and some important simplifying approximations are highlighted. PMID:20389434

Sheinfeld, Adi; Gilead, Sharon; Eyal, Avishay

2010-03-01

350

Multipath-dominant, pulsed doppler analysis of rotating blades  

CERN Document Server

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

Robinson, Michael

2012-01-01

351

Doppler reflectometry for the investigation of poloidally propagating density perturbations  

Energy Technology Data Exchange (ETDEWEB)

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 anglethe 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{mu}s. (authors)

Hirsch, M.; Baldzuhn, J.; Kurzan, B. [Max-Planck-Institut fuer Plasmaphysik, Euratom-Association, Garching (Germany); Holzhauer, E. [Stuttgart Univ. (Germany). Inst. fuer Plasmaforschung

1999-09-15

352

All semiconductor laser Doppler anemometer at 1.55 ?m  

DEFF Research Database (Denmark)

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

Hansen, Rene Skov; Pedersen, Christian

2008-01-01

353

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

354

Portable ocular laser Doppler red blood cell velocimeter  

Science.gov (United States)

A new hand-held bidirectional ocular laser Doppler system for measurement of red blood cell (RBC) velocity in retinal vessels and blood flow in the optic nerve head tissue and in the choriocapillaris is described. Laser power at the cornea is below the maximum permissible level. The instrument is based on the well-established laser Doppler velocimetry/flowmetry techniques. The optical systems for the delivery of the probing laser beam to the eye fundus and bidirectional detection of the light scattered by the RBCs have been implemented in a portable Kowa Genesis fundus camera. In vitro experiments demonstrate the performance of the instrument and in vivo measurements illustrate the feasibility of retinal blood velocity and choriocapillaris blood flow measurements in awake volunteers.

Logean, E.; Geiser, M. H.; Petrig, B. L.; Riva, C. E.

1997-07-01

355

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

356

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 equilibrium 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. 7 refs., 3 figs

357

Carotid Doppler ultrasound evaluation in patients with pulsatile tinnitus.  

Science.gov (United States)

A wide range of conditions, including atherosclerosis, may lead to pulsatile tinnitus. The objective of this study was to evaluate the patients with pulsatile tinnitus by means of carotid Doppler ultrasound parameters. Thirty-four patients with pulsatile tinnitus were enrolled in the study. Internal carotid artery intima-media thickness (IMT), blood flow velocities and arterial lumen diameters (LD) were measured and compared with the control group. Mean end diastolic velocity (EDV) (32.29 ± 17.22) and IMT (1.06 ± 0.36) values were significantly higher and mean LD (6.69 ± 1.20) was significantly lower compared to the control group. Peak systolic velocity and EDV values were significantly higher in patients whose IMT were greater than 1 mm. Pulsatile tinnitus may be the first symptom of a severe, life threatening disease. Doppler sonography is a noninvasive, safe and easily applicable diagnostic tool for the evaluation of the vascular structures, in patients with pulsatile tinnitus. PMID:25621231

Terzi, S; Arslano?lu, S; Demiray, U; Eren, E; Cancuri, O

2015-03-01

358

Ballistic Missile Warhead Recognition based on Micro-Doppler Frequency  

Directory of Open Access Journals (Sweden)

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

Sun Hui-Xia

2008-11-01

359

Rotational Dove prism scanning dual angle Doppler OCT  

Science.gov (United States)

Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its reproducibility in clinical practice. To overcome this limitation, we use a bidirectional technique with a novel rotating scanning scheme. The volume is probed simultaneously from two distinct illumination directions with variable controlled orientations, allowing reconstruction of the true flow velocity, independently of the vessel orientation. A Dove prism in the sample arm permits a rotation of the illumination directions that can be synchronized with the standard beam steering device. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to human retinal absolute blood velocity measurement by performing segment and circumpapillary time series scans around the optic nerve head. We also demonstrate microvasculature imaging by calculation of squared intensity differences between successive tomograms.

Blatter, Cedric; Coquoz, Séverine; Grajciar, Branislav; Singh, Amardeep S. G.; Werkmeister, René M.; Schmetterer, Leopold; Leitgeb, Rainer A.

2013-03-01

360

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

361

System-on-chip based Doppler radar occupancy sensor.  

Science.gov (United States)

System-on-Chip (SoC) based Doppler radar occupancy sensor is developed through non contact detection of respiratory signals. The radio was developed using off the shelf low power RF CC2530 SoC chip by Texas Instruments. In order to save power, the transmitter sends signal intermittently at 2.405 GHz. Reflected pulses are demodulated, and the baseband signals are processed to recover periodic motion. The system was tested both with mechanical target and a human subject. In both cases Doppler radar detected periodic motion closely matched the actual motion, and it has been shown that an SoC based system can be used for subject detection. PMID:22254705

Yavari, Ehsan; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

2011-01-01

362

Left coronary arterial blood flow: Noninvasive detection by Doppler US  

International Nuclear Information System (INIS)

Continuous wave (CW) and pulsed Doppler ultrasound studies with spectral analysis were used to detect the left coronary arterial blood flow in patients who were undergoing routine echocardiography. The pulmonary artery is a stable ultrasonic landmark from which detection of the blood flow can be effected. The left coronary artery can be distinguished by its blood flow toward the cardiac apex and by specific, functional flow features. Flow patterns vary among the left main, circumflex, and anterior descending arteries; patterns also vary with respiration cycles. In the present study, coronary arterial blood flow was detected in 58 of 70 patients (83%). Findings were validated by selectively injecting an agitated saline contrast medium into the left coronary artery and, in another study, by comparing human Doppler phasic flow waveforms with electromagnetic flowmeter recordings obtained in dogs

363

Doppler radar echoes of lightning and precipitation at vertical incidence  

Science.gov (United States)

Digital time series data at 16 heights within two storms were collected at vertical incidence with a 10-cm Doppler radar. On several occasions during data collection, lightning echoes were observed as increased reflectivity on an oscilloscope display. Simultaneously, lightning signals from nearby electric field change antennas were recorded on an analog recorder together with the radar echoes. Reflectivity, mean velocity, and Doppler spectra were examined by means of time series analysis for times during and after lightning discharges. Spectra from locations where lightning occurred show peaks, due to the motion of the lightning channel at the air speed. These peaks are considerably narrower than the ones due to precipitation. Besides indicating the vertical air velocity that can then be used to estimate hydrometeor-size distribution, the lightning spectra provide a convenient means to estimate the radar cross section of the channel. Subsequent to one discharge, we deduce that a rapid change in the orientation of hydrometeors occurred within the resolution volume.

Zrnic, D. S.; Rust, W. D.; Taylor, W. L.

1982-01-01

364

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)

365

Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler  

Energy Technology Data Exchange (ETDEWEB)

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

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

1990-04-01

366

SIGACE, Code for Doppler broadening of ACE-formatted files  

International Nuclear Information System (INIS)

1 - Description of program or function: SIGACE provides a method for generating high temperature ACE files for use with the MCNP code starting with a lower temperature file. IAEA1416/01: The code has been adapted to run under Linux. 2 - Methods: The low temperature ACE file is first converted to ENDF formatted file using the ACELST code and then Doppler broadened, essentially limited to the data in the resolved resonance region, to any desired higher temperature using SIGMA1. The SIGACE code then generates a high temperature ACE file for use with the MCNP code. A thinning routine has also been introduced in the SIGACE code for reducing the size of the ACE files. The Doppler Broadened ACE file can then again be converted to ENDF file and graphically plotted using EVALPLOT and compared with other ENDF file using COMPLOT routines of the PREPRO code system for validation purposes

367

Analysis on wind retrieval methods for Rayleigh Doppler lidar  

Science.gov (United States)

A modification method is described for Rayleigh Doppler lidar wind retrieval. Compared to the double-edge theory of Korb et al. [Appl. Opt., 38, 432 (1999)] and the retrieval algorithm of Chanin et al. [Geophys. Res. Lett., 16, 1273 (1989)], it has a greater sensitivity. The signal-to-noise ratio of the energy monitor channel is involved in error estimation. When the splitting ratio of the two signal channels is 1.2, which usually happened during wind detection, it will improve the measurement accuracy by about 1% at 30 km altitude for a Doppler shift of 250 MHz (44 m/s). Stabilities of retrieval methods, i.e., errors caused by the spectrum width deviation including laser pulse, Rayleigh backscatter, and filter transmission curve are first discussed. The proposed method increases the resultant precision by about 15% at 30-km altitude assuming an 8-MHz deviation in full width at half maximum of the Fabry-Perot interferometer.

Han, Yuli; Dou, Xiankang; Sun, Dongsong; Xia, Haiyun; Shu, Zhifeng

2014-06-01

368

Doppler centroid estimation ambiguity for synthetic aperture radars  

Science.gov (United States)

A technique for estimation of the Doppler centroid of an SAR in the presence of large uncertainty in antenna boresight pointing is described. Also investigated is the image degradation resulting from data processing that uses an ambiguous centroid. Two approaches for resolving ambiguities in Doppler centroid estimation (DCE) are presented: the range cross-correlation technique and the multiple-PRF (pulse repetition frequency) technique. Because other design factors control the PRF selection for SAR, a generalized algorithm is derived for PRFs not containing a common divisor. An example using the SIR-C parameters illustrates that this algorithm is capable of resolving the C-band DCE ambiguities for antenna pointing uncertainties of about 2-3 deg.

Chang, C. Y.; Curlander, J. C.

1989-01-01

369

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

370

MRI and colour-Doppler in sclerosing mesenteritis  

International Nuclear Information System (INIS)

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.)

371

Reactive Collision Avoidance for Unmanned Aerial Vehicles using Doppler Radar  

OpenAIRE

Research into reactive collision avoidance for unmanned aerial vehicles has been conducted on unmanned terrestrial and mini aerial vehicles utilising active Doppler radar obstacle detection sensors. Flight tests conducted by flying a mini UAV at an obstacle have confirmed that a simple reactive collision avoidance algorithm enables aerial vehicles to autonomously avoid obstacles. This builds upon simulation work and results obtained using a terrestrial vehicle that had already confirmed that ...

Viquerat, Andrew; Blackhall, Lachlan; Reid, Alistair; Sukkarieh, Salah; Brooker, Graham

2007-01-01

372

Detection of small UAV helicopters using micro-Doppler  

Science.gov (United States)

The detection of small unmanned aerial vehicles (UAVs) using radar can be challenging due to the small radar cross section and the presence of false targets such as birds. We present the initial results of micro-Doppler radar data collected on a small helicopter at G-band and compare the results to previously measured birds. The resulting signature differences can be used to help discriminate small UAVs from naturally occurring moving clutter such as birds.

Tahmoush, David

2014-05-01

373

Renal Power Doppler Ultrasonographic Evaluation of Children With Acute Pyelonephritis  

OpenAIRE

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 f...

Ali Pahlusi; Mahmud Fallah; Agha Smaili; Mahrooz Malek; Reza Nafisi-Moghadam; Ahmad Shajari

2011-01-01

374

Harmonic Motion Microwave Doppler Imaging method for breast tumor detection.  

Science.gov (United States)

Harmonic Motion Microwave Doppler Imaging (HMMDI) method is recently proposed as a non-invasive hybrid breast imaging technique for tumor detection. The acquired data depend on acoustic, elastic and electromagnetic properties of the tissue. The potential of the method is analyzed with simulation studies and phantom experiments. In this paper, the results of these studies are summarized. It is shown that HMMDI method has a potential to detect malignancies inside fibro-glandular tissue. PMID:25571382

Top, Can Barisc; Tafreshi, Azadeh Kamali; Gencer, Nevzat G

2014-08-01

375

WAMDII: wide-angle Michelson Doppler imaging interferometer for Spacelab  

OpenAIRE

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

376

Isometric exercise in the denervated heart: a Doppler echocardiographic study.  

OpenAIRE

The haemodynamic responses to isometric exercise of eight recipients of orthotopic heart transplants and eight healthy controls were studied. Each performed sustained exercise at 30% of maximal voluntary contraction for three minutes on a handgrip dynamometer. Cardiac output was measured by combined Doppler and cross sectional echocardiography before exercise and every 30 seconds during and after exercise. In the controls cardiac output and blood pressure increased significantly owing to an i...

Robson, S. C.; Furniss, S. S.; Heads, A.; Boys, R. J.; Mcgregor, C.; Bexton, R. S.

1989-01-01

377

Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar  

OpenAIRE

Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in par...

Shupe, M. D.; Brooks, I. M.; Canut, G.

2012-01-01

378

Doppler Radar for Heartbeat Rate and Heart Rate Variability Extraction  

OpenAIRE

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

379

A Fisheye Lens as a Photonic Doppler Velocimetry Probe  

Energy Technology Data Exchange (ETDEWEB)

These presentation visuals report an instrument that, by use of a fish-eye lens, generates a beat signal using fiber mixing of unshifted light with Doppler-shifted light and measures the beat frequency. Ray trace diagrams are shown to illustrate advantages and disadvantages. The authors find their instrument has a long tracking distance, and large angle coverage. Index matching eases assembly, reduces return loss and flattens the field.

Frogget, B. C.

2012-08-16

380

Wind Measurements with High Energy 2 Micron Coherent Doppler Lidar  

Science.gov (United States)

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

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

2004-01-01

381

HF Bistatic Ocean Doppler Spectra: Simulation Versus Experimentation  

OpenAIRE

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

Grosdidier, Samuel; Forget, Philippe; Barbin, Yves; Guerin, Charles-antoine

2013-01-01

382

Laser Doppler measurement of rectal mucosal blood flow  

OpenAIRE

BACKGROUND—Gut mucosal blood flow measurement is used to study a variety of disorders and possibly extrinsic neural function.?AIMS—To determine optimal measurement criteria and validate this technique as a measure of level of activity of extrinsic autonomic gut innervation.?METHODS—In 26 healthy volunteers a laser Doppler mucosal probe was applied 10 cm from the anus. Response to inhaled salbutamol 200 µg and ipratropium 40 µg, intravenous metoprolol 2.5 mg, and direct sacral...

Emmanuel, A.; Kamm, M.

1999-01-01

383

Maternal renaly artery doppler velocimetry in normal and hypertensive pregnancies  

OpenAIRE

Maternal Renal Artery Doppler Velocimetry in Normal and Hypertensive Pregnancies by Marius KublickasBackground. The measurement of effective renalplasma flow (ERPF) by calculation of p-aminohippurate (PAH) clearance is an invasive,time-consuming procedure. In nonpregnant hu-mans, the clearance of isotopes can be used tomeasure renal plasma flow, but the use of theseradioactive substances during pregnancy is unsuit-able. A non-invasive method for repetitive assess-...

Kublickas, Marius

1996-01-01

384

Vibration measurement by a laser Doppler displacement meter  

Science.gov (United States)

The Laser Doppler Displacement Meter (LDDM), has been applied for the measurement of structure dynamics, such as resonance frequency, Bode plot, settling time, etc. in machine tools, rotary machinery, XY-stages, and servo controls. Other applications are in micromachining and in hard disk drive, such as flight height, head gimbal resonance, runout, etc. The basic principle of the LDDM, its comparison to laser interferometer and also vibrometer, major features and application are described.

Liotto, Gianmarco; Wang, Charles P.

1996-08-01

385

Sub-Doppler modulation spectroscopy of potassium for laser stabilization  

CERN Document Server

We study modulation spectroscopy of the potassium D2 transitions at 766.7 nm. Heterodyne detection of pump-probe spectroscopy yields sub-Doppler frequency discriminants suitable for stabilizing lasers in experiments with cold atoms. Comparisons are made between spectra obtained by direct modulation of the probe beam, and those using modulation transfer from the pump via nonlinear mixing. Finally, suggestions are made for further optimization of the signals.

Mudarikwa, L; Goldwin, J

2011-01-01

386

Doppler velocity assessment of venous return in the human fetus  

OpenAIRE

Studies in the human fetus are limited by the methods available for investigation. Pressure and volume flow measurements in the fetal cardiovascular system require invasive techniques that are not performed at present. However, information on fetal circulatory performance may be helpful in the evaluation of pathologic conditions. With the introduction of Doppler ultrasound non-invasive examination of the fetal vessels became possible. In the last decade cardiovascular resear...

Huisman, T. W. A.

1993-01-01

387

Importância Prognóstica do Doppler Tecidular nos Doentes com Miocardiopatia Dilatada  

OpenAIRE

Previous studies have shown that a ratio of early transmitral flow velocity to early diastolic velocity of the mitral annulus (E/E') of > 15, obtained by tissue Doppler imaging (TDI), correlates with left ventricular filling pressure. OBJECTIVE: The aim of our study was to assess whether E/E' provides prognostic information in patients with dilated cardiomyopathy. METHODS: We studied 33 patients with dilated cardiomyopathy and mean ejection fraction of 31%. All the patients underwent ...

Galrinho, A.; Branco, Lm; Soares, Rm; Timo?teo, At; Abreu, J.; Leal, A.; Silva, S.; Cruz Ferreira, R.

2006-01-01

388

Michelson interferometer null may confirm transverse Doppler Effect  

CERN Document Server

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

Woodruff, Robert A

2014-01-01

389

Pulsed Doppler echocardiography for diagnosis of ventricular septal defects.  

OpenAIRE

In order to assess the performance of pulsed Doppler echocardiography and to examine the factors affecting its reliability for the diagnosis of ventricular septal defects, 51 patients, in whom angiographic studies had recently been performed, were investigated before and after operation by this technique. The diagnosis was correct in all cases with left-to-right shunt, when the defect was located either in the upper muscular or in the infracristal portion of the septum, even when pulmonary hy...

Magherini, A.; Azzolina, G.; Wiechmann, V.; Fantini, F.

1980-01-01

390

Validation of Imaging Doppler Interferometer Winds Using Meteor Radar  

OpenAIRE

There has been some debate over the years concerning the accuracy of mesospheric wind observations made using the imaging Doppler interferometer (IDI) technique. The high potential and increasing use of IDI wind data in joint studies with spaced-antenna MF and meteor radar systems make it important to quantify the IDI results. This paper presents a novel comparison of wind measurements between a dynasonde implementation of IDI and winds derived from an all-sky meteor radar system, a widely-ac...

Jones, G. O. L.; Fish, C. S.; Hocking, W. K.; Taylor, Michael J.

2003-01-01

391

Three-dimensional laser cooling at the Doppler limit  

OpenAIRE

Many predictions of Doppler cooling theory of two-level atoms have never been verified in a three-dimensional geometry, including the celebrated minimum achievable temperature $\\hbar \\Gamma/2 k_B$, where $\\Gamma$ is the transition linewidth. Here, we show that, despite their degenerate level structure, we can use Helium-4 atoms to achieve a situation in which these predictions can be verified. We make measurements of atomic temperatures, magneto-optical trap sizes, and the s...

Chang, Rockson; Hoendervanger, Lynn; Bouton, Quentin; Fang, Yami; Klafka, Tobias; Audo, Kevin; Aspect, Alain; Westbrook, Christoph I.; Cle?ment, David

2014-01-01

392

Jet neutral beam species measurements by Doppler-shift spectroscopy  

International Nuclear Information System (INIS)

The species mix of the JET neutral injector ion sources is measured several times per pulse for 3 seconds by Doppler-shift spectroscopy. The full-energy ratio increases with beam current: 85% for 60 Amps in hydrogen and 44 Amps in deuterium, and the half and third energy neutrals represent 10 and 5% respectively. No variation greater than ± 2% is observed throughout the pulse

393

Doppler OCT imaging of cytoplasm shuttle flow in Physarum polycephalum.  

Science.gov (United States)

The Doppler optical coherence tomography technique was applied to image the oscillatory dynamics of protoplasm in the strands of the plasmodium of slime mould Physarum polycephalum. Radial contractions of the gel-like walls of the strands and the velocity distributions in the sol-like endoplasm streaming along the plasmodial strands are imaged. The motility inhibitor effect of carbon dioxide on the cytoplasm shuttle flow and strand-wall contraction is shown. The optical attenuation coefficient of cytoplasm is estimated. PMID:19743444

Bykov, Alexander V; Priezzhev, Alexander V; Lauri, Janne; Myllylä, Risto

2009-09-01

394

Laser Doppler Flowmetry—Development and Clinical Application  

OpenAIRE

Laser Doppler Flowmetry (LDF) is an accurate and reliable method for assessing microcirculatory function. Through a series of in vitro and in vivo experiments, LDF output has been shown to be reproducible and to correlate with bone blood flow as estimated by other methods. The utility of the method in assessing meniscal, tendonous, and ligamentous perfusion has also been demonstrated. LDF has proven potential in clinical research in osteonecrosis, osteomyelitis, fracture healing, and other ar...

Swiontkowski, Marc F.

1991-01-01

395

Venous Doppler in the Evaluation of Fetal Hydrops  

OpenAIRE

Objective. To examine venous blood flow velocity in different types of fetal hydrops and its value in the prediction of outcome of pregnancies. Methods. Venous Doppler sonography was performed in 100 hydropic fetuses from 15 to 37 weeks of gestation. Blood velocity was recorded in the right hepatic vein (HV), the ductus venosus (DV) and in the intra-abdominal part of the umbilical vein (UV). Blood velocity indices were calculated and pulsations in the umbilical vein noted and grouped into a s...

Gudmundsson, S.; Hofstaetter, C.

2010-01-01

396

A wall-less vessel phantom for Doppler ultrasound studies.  

Science.gov (United States)

Doppler ultrasound flow measurement techniques are often validated using phantoms that simulate the vasculature, surrounding tissue and blood. Many researchers use rubber tubing to mimic blood vessels because of the realistic acoustic impedance, robust physical properties and wide range of available sizes. However, rubber tubing has a very high acoustic attenuation, which may introduce artefacts into the Doppler measurements. We describe the construction of a wall-less vessel phantom that eliminates the highly attenuating wall and reduces impedance mismatches between the vessel lumen and tissue mimic. An agar-based tissue mimic and a blood mimic are described and their acoustic attenuation coefficients and velocities are characterised. The high attenuation of the latex rubber tubing resulted in pronounced shadowing in B-mode images; however, an image of a wall-less vessel phantom did not show any shadowing. We show that the effects of the highly attenuating latex rubber vessels on Doppler amplitude spectra depend on the vessel diameter and ultrasound beam width. In this study, only small differences were observed in spectra obtained from 0.6 cm inside diameter thin-wall latex, thick-wall latex and wall-less vessel phantoms. However, a computer model predicted that the spectrum obtained from a 0.3-cm inside diameter latex-wall vessel would be significantly different than the spectrum obtained from a wall-less vessel phantom, thus resulting in an overestimation of the average fluid velocity. These results suggest that care must be taken to ensure that the Doppler measurements are not distorted by the highly attenuating wall material. In addition, the results show that a wall-less vessel phantom is preferable when measuring flow in small vessels. PMID:8849831

Rickey, D W; Picot, P A; Christopher, D A; Fenster, A

1995-01-01

397

Transverse flow imaging based on photoacoustic Doppler bandwidth broadening  

OpenAIRE

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

398

Doppler CO[sub 2] lidar for wind velocity measurements  

Energy Technology Data Exchange (ETDEWEB)

A monostatic biaxial Doppler lidar based on a hybrid CO[sub 2] laser with an intracavity telescopic beam expander is reported. The lidar is characterized by a laser pulse energy of 100 mJ, a pulse duration of 3-5 microsec, and a pulse repetition frequency of up to 10 Hz. The lidar is designed to measure the radial wind velocity component in the lower troposphere at distances of 3-6 km. 3 refs.

Baranov, V.IU.; Kozolupenko, V.P.; Mezhevov, V.S.; Sizov, IU.E.; Khakhlev, A.A. (Troitskii Inst. Innovatsionnykh i Termoiadernykh Issledovanii, Troitsk (Russian Federation))

1992-07-01

399

Doppler ultrasonography of hepatic artery in malignant liver tumors  

OpenAIRE

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

400

Doppler ultrasonography of hepatic artery in malignant liver tumors  

Directory of Open Access Journals (Sweden)

Full Text Available 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 cirrhosis, steatosis using these parameters in better diagnosis confirmation.

Periši? Mirjana

2008-01-01

401

The structure of Doppler peaks induced by active perturbations  

OpenAIRE

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 in...

Magueijo, J.; Albrecht, A.; Ferreira, P.; Coulson, D.

1996-01-01

402

Analytical theory of Doppler reflectometry in slab plasma model  

CERN Document Server

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.

Gusakov, E; Gusakov, Evgeniy; Surkov, Alexander

2004-01-01

403

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)

404

Avaliação do ventrículo direito pelo ecocardiograma com doppler tecidual na embolia pulmonar aguda Right ventricular assessment by tissue-Doppler echocardiography in acute pulmonary embolism  

OpenAIRE

FUNDAMENTO: A avaliação da função Ventricular Direita (VD) pelo ecocardiograma em pacientes com Tromboembolismo Pulmonar (TEP) é complexa, frequentemente qualitativa; o Doppler tecidual tem sido utilizado para avaliação semiquantitativa dessa câmara, com algumas limitações. OBJETIVO: Avaliar a função do VD no TEP pelo ecocardiograma com Doppler tecidual, complementando com o peptídeo atrial natriurético (BNP). MÉTODOS: Foram estudados pacientes com TEP pelo ecocardiograma com D...

Ana Clara Tude Rodrigues; Adriana Cordovil; Claudia Monaco; Laise Guimarães; Cury Alexandre; Naccarato, Gustavo A. F.; Edgar Lira-Filho; Claudio Henrique Fischer; Marcelo Luiz Campos Vieira; Samira Morhy

2013-01-01

405

Noninvasive monitoring of cardiac function in a chronic ischemic heart failure model in the rat: Assessment with tissue Doppler and non-Doppler 2D strain echocardiography  

OpenAIRE

Abstract Objectives Feasibility of noninvasive monitoring of cardiac function after surgically induced ischemic cardiomyopathy with tissue Doppler and non-Doppler 2D strain echocardiography in rats. Background The optimal method for quantitative assessment of global and regional ventricular function in rats with chronic heart failure for research purposes remains unclear. Methods 20 rats underwent suture ligation of the left anterior descending cor...

Baumann Gert; Konertz Wolfgang; Heinze Georg; Knebel Fabian; Holinski Sebastian; Borges Adrian C

2011-01-01

406

Holographic laser Doppler imaging of microvascular blood flow  

Science.gov (United States)

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

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

2014-12-01

407

Transthoracic ultrafast Doppler imaging of human left ventricular hemodynamic function.  

Science.gov (United States)

Heart diseases can affect intraventricular blood flow patterns. Real-time imaging of blood flow patterns is challenging because it requires both a high frame rate and a large field of view. To date, standard Doppler techniques can only perform blood flow estimation with high temporal resolution within small regions of interest. In this work, we used ultrafast imaging to map in 2-D human left ventricular blood flow patterns during the whole cardiac cycle. Cylindrical waves were transmitted at 4800 Hz with a transthoracic phased-array probe to achieve ultrafast Doppler imaging of the left ventricle. The high spatio-temporal sampling of ultrafast imaging permits reliance on a much more effective wall filtering and increased sensitivity when mapping blood flow patterns during the pre-ejection, ejection, early diastole, diastasis, and late diastole phases of the heart cycle. The superior sensitivity and temporal resolution of ultrafast Doppler imaging makes it a promising tool for the noninvasive study of intraventricular hemodynamic function. PMID:25073134

Osmanski, Bruno-Felix; Maresca, David; Messas, Emmanuel; Tanter, Mickael; Pernot, Mathieu

2014-08-01

408

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

409

Airborne Doppler radar detection of low altitude windshear  

Science.gov (United States)

As part of an integrated windshear program, the Federal Aviation Administration, jointly with NASA, is sponsoring a research effort to develop airborne sensor technology for the detection of low altitude windshear during aircraft take-off and landing. One sensor being considered is microwave Doppler radar operating at X-band or above. Using a Microburst/Clutter/Radar simulation program, a preliminary feasibility study was conducted to assess the performance of Doppler radars for this application. Preliminary results from this study are presented. Analysis show, that using bin-to-bin Automatic Gain Control (AGC), clutter filtering, limited detection range, and suitable antenna tilt management, windshear from a wet microburst can be accurately detected 10 to 65 seconds (.75 to 5 km) in front of the aircraft. Although a performance improvement can be obtained at higher frequency, the baseline X-band system that was simulated detected the presence of a windshear hazard for the dry microburst. Although this study indicates the feasibility of using an airborne Doppler radar to detect low altitude microburst windshear, further detailed studies, including future flight experiments, will be required to completely characterize the capabilities and limitations.

Bracalente, Emedio M.; Jones, William R.; Britt, Charles L.

1990-01-01

410

Doppler radar wind field retrieval over the Po Valley  

Directory of Open Access Journals (Sweden)

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

Y. K. Goh

2006-01-01

411

Diagnostic sensitivity and specificity of Doppler ultrasound in rheumatoid arthritis  

DEFF Research Database (Denmark)

Objective. To evaluate the sensitivity and specificity of Doppler ultrasound (DUS) in diagnosing arthritis in the wrist and hands, and, if possible, to define a cutoff level for our ultrasound measures for inflammation, resistive index (RI), and color fraction. Methods. Using DUS, 88 patients with active RA were selected for study and 27 healthy controls. A total of 419 joints were examined. The synovial vascularization was determined by color Doppler and spectral Doppler estimating the color fraction (the percentage of color pixels inside the synovium was the region of interest) and RI in wrist, metacarpophalangeal (MCP), and proximal interphalangeal (PIP) joints. Receiver-operator characteristic (ROC) curves were made for both US measures. Cutoff levels were selected from the ROC curves as the values with the optimum sensitivity and specificity. Results. Analyses were carried out for small joints (MCP and PIP), wrists, and for all joints (pooled). Pooled joint analysis showed the area under the curve for both RI and color fraction was 0.84. The cutoff level for the color fraction was 0.01 and for RI 0.83. With these cutoff levels, the sensitivity and specificity for the color fraction were 0.92 and 0.73, respectively. For RI a sensitivity of 0.72 and specificity of 0.70 were found. Analysis of small joints and wrist gave very similar results. Conclusion. DUS may detect vascularization of the inflamed synovium with a high sensitivity and a moderate specificity with selected cutoff levels Udgivelsesdato: 2008/1

Terslev, L.; Recke, P. von der

2008-01-01

412

Full motion and flow field recovery from echo Doppler data.  

Science.gov (United States)

We present a new computational method for reconstructing a vector velocity field from scattered, pulsed-wave ultrasound Doppler data. The main difficulty is that the Doppler measurements are incomplete, for they do only capture the velocity component along the beam direction. We thus propose to combine measurements from different beam directions. However, this is not yet sufficient to make the problem well posed because 1) the angle between the directions is typically small and 2) the data is noisy and nonuniformly sampled. We propose to solve this reconstruction problem in the continuous domain using regularization. The reconstruction is formulated as the minimizer of a cost that is a weighted sum of two terms: 1) the sum of squared difference between the Doppler data and the projected velocities 2) a quadratic regularization functional that imposes some smoothness on the velocity field. We express our solution for this minimization problem in a B-spline basis, obtaining a sparse system of equations that can be solved efficiently. Using synthetic phantom data, we demonstrate the significance of tuning the regularization according to the a priori knowledge about the physical property of the motion. Next, we validate our method using real phantom data for which the ground truth is known. We then present reconstruction results obtained from clinical data that originate from 1) blood flow in carotid bifurcation and 2) cardiac wall motion. PMID:17243582

Arigovindan, Muthuvel; Sühling, Michael; Jansen, Christian; Hunziker, Patrick; Unser, Michael

2007-01-01

413

Gestational trophoblastic neoplasia: efficacy of color doppler ultrasound  

International Nuclear Information System (INIS)

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

414

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

415

Rotational Doppler shift of the phase-conjugated photon  

CERN Document Server

The rotational Doppler shift of a photon with angular momentum $\\pm \\ell \\hbar$ is shown to be an even multiple of the angular frequency $\\Omega$ of the noninertial reference frame when photon is reflected from the phase-conjugating mirror (PCM). In particular in the rotating vehicle the phase-conjugating optical setup where the angular momentum of the $\\ell $-charged optical vortex is altered $N$ times will demonstrate the $\\delta \\omega=4 (N+1/2) \\ell \\cdot \\Omega$ rotational Doppler shift. This happens due to the opposite orbital angular momenta of the counter propagating photon states and this leads to the rotation of the helical interference pattern with angular frequency $\\delta \\omega$. In an inertial reference frame when PCM is in rest and rotation is due to a single image-inverting component alike Dove-prism the frequency shift is $4 \\ell \\cdot \\Omega$. The non conjugating retroreflector alike parabolic confocal mirror cancels the rotational Doppler shift (if the latter appears in a some image-invert...

Okulov, A Yu

2011-01-01

416

Estudo da macrovasculatura por ultra-sonografia Doppler na esclerose sistêmica / Study of macrovasculature by Doppler ultrasound in systemic sclerosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Avaliar a ocorrência e a distribuição das alterações macrovasculares em uma população com esclerose sistêmica (ES) por meio da ultra-sonografia Doppler (USG Doppler) e do índice tornozelo-braço (ITB). Foi investigada a associação destes achados com as características demográficas e clínica [...] s dos pacientes, bem como fatores de risco e antecedentes da doença ateromatosa. MÉTODOS: Estudo prospectivo, tipo série de casos, constituído de 20 pacientes, sendo 19 do sexo feminino, com idade média de 46,30 anos. A forma clínica difusa esteve presente em 85% dos pacientes. Todos tinham fenômeno de Raynaud (FR), 55% apresentaram alteração de polpas digitais, 15% úlcera atual de membros e 25% reabsorção de falange. Não houve amputação e 70% apresentaram de um a quatro fatores de risco de aterosclerose. A aorta, as carótidas, bem como as artérias dos membros superiores (MMSS) e inferiores (MMII) foram estudadas por USG Doppler para a avaliação de espessamento do complexo íntima-medial (CIM), presença de placas e aneurismas. Nas artérias dos MMII, foi também realizado o ITB. RESULTADOS: O ITB foi normal em todos os pacientes, entretanto 12 (60%) destes apresentaram doença macrovascular (DMV), sendo 9 (45%) na aorta, 7 (35%) nos MMII, 6 (30%) nas carótidas e 1 (5%) nas artérias dos MMSS. Observou-se associação entre DMV e alterações de polpas digitais (p = 0,0045). CONCLUSÕES: A USG Doppler identificou DMV em 60% dos pacientes com ES. Nenhum paciente apresentou ITB anormal. Verificou-se associação significante da DMV com as alterações atuais de polpas digitais. As alterações macrovasculares encontradas não estão necessariamente associadas à esclerose sistêmica e podem decorrer do processo aterosclerótico. Abstract in english OBJECTIVE: To assess the occurrence and distribution of the macrovascular alterations in a population with Systemic Sclerosis (SS) by means of Doppler ultrasound (Doppler US) and ankle-arm index (AAI). To investigate the assotiation of these findings with both demographic and clinical characteristic [...] s in the patients as well as with risk factors and antecedents of atheromatous disease. METHODS: Prospective study, of the series of cases type, comprising 20 patients, 19 of whom were women with a median age of 46.30 years. Eighty-five percent were of the diffuse form. All the patients had the Raynaud's phenomenon, 55% presented alteration of digital pulps, 15% current limb ulcers and 25% phalanx resorption. There were no amputations and 70% presented from 1 to 4 risk factors for atherosclerosis. The aorta, carotids as well as upper (ULs) and lower (LLs) limbs arteries were evaluated by Doppler US to assess thickening of the medio-intimal complex (MIC), presence of plaques and aneurisms. In the arteries of the LLs, AAI was also undertaken. RESULTS: AAI was normal in all patients, 12 patients (60%) presented macrovascular disease (MVD) comprising 9 (45%) of these in the aorta, 7 (35%) in LLs arteries , 6 (30%) in the carotids and 1 (5%) in ULs arteries. MVD and alterations of digital pulps were positivily associated (p = 0.0045). CONCLUSIONS: Doppler US identified MVD in 60% of our SS patients. No patients had abnormal AAI. MDV was positivily associated with digital pulps alterations. The macrovascular alterations found are not necessarily associated with systemic sclerosis, and may be due to atherosclerosis process.

Emmanuelle Tenório Albuquerque Madruga, Godoi; Alexandre Domingues, Barbosa; Juannicelle Tenório Albuquerque Madruga, Godoi; Mariana Atanásio Morais, Ramos; Jocelene Tenório Albuquerque Madruga, Godoi; Sílvio Romero de Barros, Marques; Ângela Luzia Branco Pinto, Duarte.

2008-04-01

417

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

418

Doppler echocardiographic features of coronary arteriovenous fistula. Complementary roles of cross sectional echocardiography and the Doppler technique.  

OpenAIRE

The Doppler echocardiographic features of coronary arteriovenous fistula were investigated in eight patients with left or right coronary arteriovenous fistulas who had a continuous heart murmur in the upper precordial area and whose diagnoses were confirmed by coronary angiography. In four patients the dilated lumen of the coronary arteriovenous fistula was visualised by cross sectional echocardiography. Of these, three showed abnormal unidirectional continuous flow signals with broad velocit...

Miyatake, K.; Okamoto, M.; Kinoshita, N.; Fusejima, K.; Sakakibara, H.; Nimura, Y.

1984-01-01

419

As diferenças do Doppler espectral, na artrite psoriática e onicomicose / Differences of spectral Doppler in psoriatic arthritis and onychomycosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Objetivo Utilizar o Doppler espectral (DE) para quantificar atividade inflamatória e detectar diferenças ecotexturais ungueais em pacientes com artrite psoriásica e onicomicose. Métodos Foram incluídos dois pacientes, um com artrite psoriásica, mas sem dores nas articulações e sem alterações clín [...] icas ungueais; e outro paciente com onicomicose e artrite reumatoide. O exame de ultrassom, pela escala cinza, demonstrou alterações na presença regular da ecotextura na inserção da unha, aumento da espessura do leito ungueal e perda do padrão trilaminar da unha. O Doppler espectral, através do índice de resistência (IR), detecta o processo inflamatório nas enteses ungueais. Resultados Sete articulações interfalângicas distais (IFD) nos dois pacientes foram avaliadas em dois planos, obtendo nove IR. O autor encontrou no paciente com artrite psoriásica: perda normal do padrão trilaminar da unha; leitos ungueais e cápsulas articulares das IFDs preservados. O Doppler espectral evidenciou IR1, com média±DP igual a 1,71±0,98. Conclusão O uso do ultrassom pode detectar alterações nos leitos ungueais nessas doenças. Futuros estudos poderão melhor caracterizar essas mudanças. Abstract in english Objective To evaluate the use of the spectral Doppler (SDoppler) to quantify inflammatory activity and to detect nail echotextural differences in patients with psoriatic arthritis and onychomycosis. Methods Two patients, one with psoriatic arthritis but with no joint pain nor nail clinical change [...] and the other with onychomycosis and rheumatoid arthritis were included. The gray scale ultrasound study, showed changes in the regular presence of echotexture at the nail insertion, thickening of the nail bed and loss of trilaminar nail pattern. The spectral Dopplerresistance index (RI), detects the inflammatory process in nail entheses. Results Seven distal interphalangeal (DIP) joints in both patients were evaluated in two planes, getting nine RI. In the patient with psoriatic arthritis the author found: loss of normal trilaminar nail plate aspect, and nail beds and DIP joint capsules preserved. The spectral Doppler showed RI1, with mean±SD=1.71±0.98. Conclusion The use of ultrasound can detect changes in the nail beds in these diseases. Future studies will further characterize these changes.

José Alexandre, Mendonça.

2014-12-01

420

Solid breast lesions: evaluation with power versus conventional color doppler sonography  

International Nuclear Information System (INIS)

To compare power and conventional color Doppler sonography for depiction of the vasculature of solid breast lesions, and to evaluate the usefulness of power Doppler sonography for differential diagnosis of malignant breast lesions. In order to detect vascularity, 82 cases of solid breast lesions were evaluated by power and color Doppler sonography. Fifty-eight pathologically proven cases (37 benign and 21 malignant lesions) were analyzed for the amount and patterns of Doppler signals, morphology of vessels, and the diagnostic accuracy. In 45 of 82 cases, power Doppler sonography depicted flow better than did color Doppler sonography, while in 37 cases, depiction was equal. On power Doppler sonography, the incidence of marked blood flow in malignant lesions was three times higher than in benign lesions. The pattern of vasculature was more predominantly central (85.5%) and penetrating (61.9%) in malignant lesions than in benign lesions. Branching (57.1%) and disordered vessels (33.3%) were more frequent in malignant lesions than in benign. For the diagnosis of malignancy, sensitivity for power Doppler sonography was 65%, specificity was 79% and diagnostic accuracy was 74.1%;for color Doppler sonography, the corresponding figures wore 76.2%, 74.8% and 75.1%. Power Doppler sonography was more sensitive than color Doppler sonography for the detection of flow in solid breast lesions. For the differentiation of benign from malignant lesions, however, there was no difference lesions, however, there was no difference in diagnostic accuracy between the two modalities. Findings of central and penetrating distribution patterns of Doppler signals, and branching and disordered shapes of vessels, along with other sonographic criteria, are helpful for predicting malignancy

421

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

OpenAIRE

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 ...

Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

2010-01-01

422

Changes in Doppler indices of cardiac function during and after percutaneous transluminal coronary angioplasty.  

OpenAIRE

OBJECTIVE--To assess the sensitivities of Doppler indices to changes in global cardiac function during and after controlled myocardial ischaemia induced by coronary angioplasty. DESIGN--Continuous wave Doppler signals of aortic flow were recorded during coronary angioplasty. The following Doppler indices of cardiac function were measured before, during, and after balloon inflation: V (peak velocity), MA (mean acceleration), V2/T (T = time from onset to peak ejection), and MD (minute distance ...

Hunt, A. C.; Chow, S. C.; Escaned, J.; Perry, R. A.; Seth, A.; Shiu, M. F.

1991-01-01

423

Pulsed and Tissue Doppler Echocardiographic Changes in Patients with Thalassemia Major  

OpenAIRE

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...

Garadah, Taysir S.; Salah Kassab; Najat Mahdi; Ahmed Abu-Taleb; Anwer Jamsheer

2010-01-01

424

Transcutaneous Doppler ultrasound measurement of superior mesenteric artery blood flow in man.  

OpenAIRE

A duplex scanner which consists of a real time two dimensional scanner and a pulsed Doppler flowmeter was used to measure superior mesenteric blood flow in 70 healthy subjects. By processing the Doppler shift signals, the instantaneous average Doppler shift frequency and then the instantaneous average velocity of the flow rate were calculated. Both diameter of the vessel and angle between vessel and beam were measured from real time imaging. The mean (+/- standard error of the mean) of the su...

Qamar, M. I.; Read, A. E.; Skidmore, R.; Evans, J. M.; Wells, P. N.

1986-01-01

425

Limitations in assessing the severity of aortic stenosis by Doppler gradients.  

OpenAIRE

Continuous wave Doppler echocardiography was performed before cardiac catheterisation in 69 consecutive patients with suspected aortic stenosis. Agreement between the maximum and the mean Doppler gradients and catheterisation gradients was good. Doppler echocardiography, however, systematically underestimated the maximum and mean gradients, particularly in the high range. Stepwise regression analysis of the small pressure difference between the two methods showed that it could not be explaine...

Danielsen, R.; Nordrehaug, J. E.; Stangeland, L.; Vik-mo, H.

1988-01-01

426

Fixed-delay Interferometry for Doppler Extra-solar Planet Detection  

OpenAIRE

We present a new technique based on fixed-delay interferometry for high throughput, high precision and multi-object Doppler radial velocity (RV) surveys for extra-solar planets. The Doppler measurements are conducted through monitoring the stellar fringe phase shifts of the interferometer. High Doppler sensitivity is achieved through optimizing the optical delay in the interferometer and reducing photon noise by measuring multiple fringes over a broadband. This broadband ope...

Ge, Jian

2002-01-01

427

MESURE DE VITESSE PAR DOPPLER ULTRASONORE : COMPARAISON DE DIFFÉRENTES TECHNIQUES D'ANALYSE TEMPS-FRÉQUENCE  

OpenAIRE

L'effet Doppler permet de transposer une mesure de vitesse en une mesure de fréquence. Lorsque la vitesse d'une cible évolue en fonction du temps une analyse spectrale du signal Doppler est insuffisante. Dans cette article nous comparons, sur des signaux de simulation et sur des signaux réels de bulles en mouvement, les performances de deux techniques fournissant la fréquence instantanée d'un signal : une méthode basée sur le calcul du signal analytique associé au signal Doppler et la...

Cachard, C.; Zhu, Y.; Gimenez, G.; Peyrin, F.

1990-01-01

428

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

OpenAIRE

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...

Risti? Slavica S.; Ili? Jelena T.; ?antrak ?or?e S.; Risti? Ognjen R.; Jankovi? Novica Z.

2012-01-01

429

Spectral Doppler ultrasound in the major arteries of normal conscious immature micropigs  

OpenAIRE

Spectral waveform analysis of blood flow velocity in the major arteries of six healthy, conscious immature micropigs was determined using Doppler ultrasonography. Doppler spectral tracings were recorded from the external iliac artery, femoral artery, and renal arcuate artery. Tracings were also taken from three parts of the common carotid artery and two parts of the abdominal aorta. Spectral Doppler parameters included peak systolic velocity, early diastolic velocity, peak systolic velocity-t...

Jung, Joohyun; Chang, Jinhwa; Oh, Sunkyoung; Choi, Mincheol

2010-01-01

430

Micro-Doppler analysis of non-stationary moving targets in radar imaging  

OpenAIRE

n traditional ISAR imaging, rigid-body motion is usually assumed without considering non-stationary targets. Relative motion or deformation of parts of illuminated objects induce additional features in the Doppler frequency spectra. These features are called micro-Doppler effect and appear as sidebands around the central Doppler frequency. They can provide valuable information about the structure of the moving parts and may be used for recognition purposes. Previous papers have mostly focused...

Ghaleb, Antoine

2009-01-01

431

Wearable Doppler radar with integrated antenna for patient vital sign monitoring  

OpenAIRE

A 2.45 GHz wearable Doppler radar unit with radio data link is presented for use in portable patient monitoring and emergency response. Unlike portable Electrocardiograms (ECG) or Photoplethysmography (PPG), the near-field Doppler unit enables monitoring of the person's heart rate without the need for electrical contact or optical access to the patient's skin. The Doppler unit is designed to be embedded in a clothing garment such as a shirt or vest, or used by medical emergency personal in an...

Fletcher, Richard Ribon; Kulkarni, Sarang

2010-01-01

432

Feasibility of Doppler variance imaging for red blood cell aggregation characterization  

OpenAIRE

An abnormal level of red blood cell (RBC) aggregation is a clinical condition associated with many pathologies. Our purpose is to investigate the feasibility of spectral domain phase-resolved optical Doppler tomography incorporated with Doppler variance imaging to characterize RBC aggregation in flowing blood. Variance?standard deviation (SD) of the Doppler frequency spectrum of porcine blood flowing through a glass tube (diameter 300 ?m) at 4.7 mm?s is measured. For nonaggregating RBCs ...

Xu, Xiangqun; Ahn, Yeh-chan; Chen, Zhongping

2009-01-01

433

A comparison of pulmonary valve gradient measurement by doppler and catheterization  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, trans-pulmonic valvular gradient of 51 patients with congenital pulmonary stenosis measured by CW-Doppler and cardiac catheterization were compared to find whether they are comparable and if Doppler method is accurate enough for interventional decision-making. Results showed that findings in both methods were comparable and Doppler method is accurate and enough for clinical decision.

Ranjbar Nejad H

1997-08-01

434

Pulsed doppler tissue imaging in the early diagnosis of coronary artery disease  

OpenAIRE

Introduction Cardiovascular diseases are the leading cause of death in the majority of well-developed countries. Importance of early diagnosis Early diagnosis of coronary artery disease is difficult due to blood vessels remodeling, late manifestations of reduced maximal and normal coronary blood flow, and negative correlation between stenosis and plaque burden. Pulsed Doppler tissue imaging Pulsed Doppler tissue imaging is used for assessment of myocardial velocity, whereas classical Doppler ...

Zdravkovi? Marija; Deljanin-Ili? Marina; Trifunovi?-Zamaklar Danijela; Milini? Nikola; Zdravkovi? Darko; Mili? Nataša

2007-01-01

435

Potential use of Doppler perfusion index in detection of occult liver metastases from colorectal cancer  

OpenAIRE

Many clinical and preclinical studies demonstrated that measurements of liver hemodynamic [Doppler perfusion index (DPI)] may be used to accurately diagnose and predict liver metastases from primary colorectal cancer in a research setting. However, Doppler measurements have some serious limitations when applied to general population. Ultrasound is very operator-dependent, and requires skilled examiners. Also, many conditions may limit the use of Doppler ultrasound and ultrasound in general, s...

Kopljar, Mario; Patrlj, Leonardo; Bus?ic?, Z?eljko; Kolovrat, Marijan; Rakic?, Mislav; Klic?ek, Robert; Z?idak, Marcel; Stipanc?ic?, Igor

2014-01-01

436

Doppler Parameters of Hepatic and Renal Hemodynamics in Patients with Liver Cirrhosis  

OpenAIRE

Introduction. There are limited studies on simultaneous evaluation of liver and renal blood flow using Doppler methods. We evaluated and compared the changes of liver and renal Doppler US parameters in patients with liver cirrhosis according to the degree of liver disease. Material and Methods. We assessed a large spectrum of liver and renal Doppler US parameters in 67 patients with liver cirrhosis. Results. Significant differences between Child's classes or score, as well as MELD score, were...

Popov, D.; Krasteva, R.; Ivanova, R.; Mateva, L.; Krastev, Z.

2012-01-01

437

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

438

Uncertainty of Doppler reactivity worth due to uncertainties of JENDL-3.2 resonance parameters  

International Nuclear Information System (INIS)

Analytical formula of Resonance Self-shielding Factor (f-factor) is derived from the resonance integral (J-function) based on NR approximation and the analytical expression for Doppler reactivity worth (?) is also obtained by using the result. Uncertainties of the f-factor and Doppler reactivity worth are evaluated on the basis of sensitivity coefficients to the resonance parameters. The uncertainty of the Doppler reactivity worth at 4870K is about 4 % for the PNC Large Fast Breeder Reactor. (author)

439

Optimal Estimation Of Range And Doppler Centroid In ScanSAR  

Science.gov (United States)

Algorithm processes synthetic-aperture-radar (SAR) returns into optimal estimates of ranges, pointing angles, and Doppler centroids. Derives radar-beam-pointing angles partly from SAR data. Exploits information available in overlapping regions between adjacent image bursts or, equivalently, between adjacent radar beams corresponding to adjacent image bursts. Range or Doppler centroid obtained from estimate of range or Doppler value at which intensity in one image burst equals that in adjacent burst.

Jin, Michael Y.

1995-01-01

440

Measurement of Doppler effect up to 2000 degree C at FCA  

International Nuclear Information System (INIS)

Most Doppler effect measurements so far have been carried out in the temperature range from 20 to 800 degree C at various fast critical facilities around the world. The Doppler effect at higher temperature plays an important role in the transient behavior of the fast breeder reactor. To improve the accuracy of Doppler effect calculations in the high-temperature range, new devices were developed to measure the Doppler effect up to 2000 degree C, and measurements were carried out at Fast Critical Assembly (FCA) at the Japan Atomic Energy Research Institute

441

High resolution Doppler lidar based on actively stabilized ring dye laser  

International Nuclear Information System (INIS)

A CW Doppler lidar has been developed. Heterodyne detection techniques are used for the recording of Doppler shifted collected backscattered signals induced by the motion of remote sources. The system has been tested for remote measurements of Doppler shifts due to rotating objects, aerosols and flowing liquids. Water and gaseous discharge flow rates have been measured remotely for simulation purposes. The system is capable of measuring Doppler shifts as low as 0.25 MHz corresponding to 0.1 m/sec velocities

442

Evaluation of color doppler ultrasonographic findings in cases with cervical lymphadenomegaly and histopathological correlation  

Directory of Open Access Journals (Sweden)

Full Text Available Objective: Our aim is to evaluate effectivity of color Doppler ultrasonography in differentiation of benign and malign lymph nodes in patients with cervical lymphadenomegaly, regarding histopathological results. Material and methods: Histopathological analysis was made to 20 patients with cervical lympadenomegaly after color Doppler ultrasonographic examinations. Results: Histopathologic results of 20 lymph nodes were: 7 reactive, 5 tuberculosis, 4 lymphoma, and 4 other malign lesions. Conclusion: In patients with cervical lymphadenomegaly, color Doppler ultrasonography was found to give additive information in differentiation of benign and malign lymph nodes with combined use of nodal vascularity pattern and color Doppler spectral analysis, to the other diagnostic modalities.

Edip Hatipo?lu

2008-01-01

443

High-frequency Ultrasound Doppler System for Biomedical Applications with a 30 MHz Linear Array  

OpenAIRE

In this paper, we report the development of the first high-frequency (HF) pulsed-wave Doppler system using a 30 MHz linear array transducer to assess the cardiovascular functions in small animal. This array based pulsed-wave Doppler system included a 16-channel HF analog beamformer, a HF pulsed-wave Doppler module, timing circuits, HF bipolar pulsers, and analog front-ends. The beamformed echoes acquired by the 16 channel analog beamformer, were directly fed to the HF pulsed-wave Doppler modu...

Xu, Xiaochen; Sun, Lei; Cannata, Jonathan M.; Yen, Jesse T.; Shung, K. Kirk

2008-01-01

444

Doppler color flow mapping of peripheral vessels: Comparison of angiodynography with conventional duplex US  

International Nuclear Information System (INIS)

A new Doppler color flow imager was compared to duplex US in the evaluation of carotid and peripheral vessels in 50 patients. A 7.5-MHz transducer permitted simultaneous high-resolution real-time imaging of Doppler flow and tissue. The system was found to have excellent image quality and Doppler sensitivity. Flow characteristics and velocity measurements obtained with this system correlated well with those obtained using the duplex scanner and were obtained more quickly than with the conventional system, allowing more complete assessment of flow characteristics. Color Doppler flow imaging appears to be an extremely promising method for the rapid and effective evaluation of peripheral vascular flow

445

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

446

[Longitudinal analysis of arterial Doppler parameters in growth retarded fetuses].  

Science.gov (United States)

Doppler parameters enable noninvasive and direct detection of placental insufficiency and brain sparing effect, which occurs as an adaptive mechanism to chronic hypoxemia. It is of great interest if further changes of Doppler parameters, which occur after the detection of the first pathologic value, can anticipate a moment of fetal distress. We investigated growth-restricted fetuses with the brain sparing effect in the time interval between the detection of blood flow redistribution until the distress. The aim of our study was to evaluate longitudinally Doppler parameters in umbilical (Aum), medial cerebral (MCA), renal (AR) and femoral (AF) artery, and find: 1) if there are significant changes in their value; 2) the character and time interval of these changes; and 3) if they differ from changes in biophysical profile (BFP). Prospective clinical study evaluated 35 pregnancies with fetal growth restriction. Fetuses were selected for the study if: 1) there were pathologic cerebral/umbilical (C/U) ratio, 2) at least four Doppler examinations in 3-4 days interval were performed and 3) prepartal fetal distress, defined as silent fetal heart rate pattern with spontaneous and late decelerations, was present. In 28 neonates after delivery umbilical artery gas and acid-base status was determined. Blood flow velocity waveforms were evaluated in Aum, MCA, AR, and AF. Arterial blood flow was estimated by pulsatility index (Pi), while in Aum we also used: present end-diastolic velocity (PEDV), absent end-diastolic velocity (AEDV) and reverse end-diastolic velocity (REDV). All of the fetuses were monitored by cardiotocogram (CTG) once to twice a day and by BFP twice a week. Elective Cesarean section was done in the presence of distress, except if severe immaturity or extreme malnutrition occurred. Etiological factors of placental insufficiency were: 1) hypertensive syndrome (n = 26), 2) chronic renal disease (n = 3), 3) primary antiphospholipid syndrome (n = 2), 4) diabetes mellitus (n = 1), 5) cardiac disease (n = 1) and 6) unknown (n = 2). Initial Doppler examination, with the detection of pathological C/U, was done in time interval between 26. to 32. weeks of gestation (wg) (29.4 +/- 2.5); delivery was between 29. to 34. wg (32.2 +/- 1.9); and average body weight was 1327 +/- 245 g. Pathological BFP was registered in 91.4% of fetuses. Cesarian section has not been done, in spite of distress, in two fetuses (5.7%) due to their extreme immaturity and/or malnutrition, so they died "in utero". Hypoxemia was registered in 96.4% (27/28) neonates, while acidosis in 71.4% (20/28). Neonatal morbidity was 93.9% (31/33), neonatal mortality 8.6%, while perinatal mortality was 14.3%. We found high significant difference (P Three weeks before the distress in 7 (53.8%) cases we registered PEDV, in 6 (46.2%) AEDV, while we didn't register REDV in any case. In the last week there were 3 (8.6%) PEDV, 23 (65.7%) AEDV and 9 (25.7%) REDV. Significant changes in Doppler parameters suggest that even after the blood redistribution in growth restricted hypoxemic fetuses further haemodynamic changes occur. Preterminal increase in Pi Aum can be due to: 1) release of leucotrien, tromboxan and free oxygen radicals and consecutive vasoconstriction in villous arteries; 2) increase of diastolic arterial pressure as a result of hypoxic-ischemic central nervous system (CNS) insult; 3) decreased combined heart minute volume in preterminal phase of hypoxemia. The increase of Pi MCA values is a result of hypoxic-ischemic CNS insult. As a c

Mikovi?, Zeljko; Mandi?, Vesna; Djuki?, Milan; Egi?, Amira; Filimonovi?, Dejan; Cerovi?, Nikola; Popovac, Mirjana

2003-01-01

447

Colour doppler ultrasound assessment of the normal neonatal hip  

International Nuclear Information System (INIS)

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

448

Implementation of on-the-fly doppler broadening in MCNP  

Energy Technology Data Exchange (ETDEWEB)

A new method to obtain Doppler broadened cross sections has been implemented into MCNP, removing the need to generate cross sections for isotopes at problem temperatures. When a neutron of energy E enters a material region that is at some temperature T, the cross sections for that material at temperature T are immediately obtained 'on-the-fly' (OTF) by interpolation using a high order functional expansion for the temperature dependence of the Doppler-broadened cross section for that isotope at the neutron energy E. The OTF cross sections agree with the NJOY-based cross sections for all neutron energies and all temperatures in the range specified by the user, e.g., 250 K - 3200 K. The OTF methodology has been successfully implemented into the MCNP Monte Carlo code and has been tested on several test problems by comparing MCNP with conventional ACE cross sections versus MCNP with OTF cross sections. The test problems include the Doppler defect reactivity benchmark suite and two full-core VHTR configurations, including one with multiphysics coupling using RELAP5-3D/ATHENA for the thermal-hydraulic analysis. The comparison has been excellent, verifying that the OTF libraries can be used in place of the conventional ACE libraries generated at problem temperatures. In addition, it has been found that the OTF methodology greatly reduces the complexity of the input for MCNP, resulting in an order of magnitude decrease in the number of input lines for full-core configurations. Finally, for full-core problems with multiphysics feedback, the memory required to store the cross section data is considerably reduced with OTF cross sections and the additional computational effort with OTF is modest, on the order of 10-15%. (authors)

Martin, W. R.; Wilderman, S. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan (United States); Brown, F. B. [Los Alamos National Laboratory (United States); Yesilyurt, G. [Argonne National Laboratory (United States)

2013-07-01

449

Cancer therapy and cardiotoxicity: The need of serial Doppler echocardiography  

Directory of Open Access Journals (Sweden)

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

Pardo Moira

2007-01-01

450

From HARPS to CODEX: exploring the limits of Doppler measurements  

Science.gov (United States)

Only 3 6 years ago, the Doppler technique was believed to have reached its final limitations in measuring stellar velocities and finding extra-solar planets. The 3 4 m s-1 precision level achieved, at that time, by various teams, was certainly limited by instrumental performances, but also constrained, as believed by a part of the