WorldWideScience

Sample records for doppler image-derived tei

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Javier González Fernández

    2004-08-01

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

  3. 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)

  4. Evaluation of right ventricular performance long after the atrial switch operation for transposition of the great arteries using the Doppler Tei index.

    Science.gov (United States)

    Takeuchi, D; Nakanishi, T; Tomimatsu, H; Nakazawa, M

    2006-01-01

    Right ventricular (RV) dysfunction may occur in patients after the atrial switch operation for d-transposition of the great arteries (d-TGA) and can be an important complication. Noninvasive assessment of RV function using echocardiography is necessary for following up these patients. We evaluated RV function using the Doppler Tei index (RV Tei index). The RV Tei index measures the ratio of total time intervals in isovolumetric contraction and relaxation to the ejection time. The subjects consisted of 33 patients who had undergone the atrial switch operation for d-TGA (the atrial switch group) (mean age, 21 +/- 4 years), 10 patients with pulmonary artery stenosis after the arterial switch operation for d-TGA (the arterial switch group) (mean age, 17 +/- 1 years), and 10 patients with a normally structured heart as a control group (mean age, 26 +/- 7 years). The RV Tei index (0.65 +/- 0.16) was significantly higher in the atrial switch group than in the arterial switch group (0.29 +/- 0.07) and the control group (0.29 +/- 0.01) (p d-TGA. PMID:16132297

  5. 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)

    Silvio Henrique Barberato

    2006-06-01

    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.

  6. Teaching TEI: The Need for TEI by Example

    OpenAIRE

    Terras, M.; Van den Branden, R.; Vanhoutte, E.

    2009-01-01

    The Text Encoding Initiative (TEI)1 has provided a complex and comprehensive system of provisions for scholarly text encoding. Although a major focus of the ‘digital humanities’ domain, and despite much teaching effort by the TEI community, there is a lack of teaching materials available, which would encourage the adoption of the TEI's recommendations and the widespread use of its text encoding guidelines in the wider academic community. This article describes the background, plans, and a...

  7. 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)

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

    2010-06-01

    Full Text Available 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).

  8. Right Ventricular Tissue Doppler in Space Flight

    Science.gov (United States)

    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

    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.

  9. Intraoperative transesophageal echocardiographic assessment of left ventricular Tei index in congenital heart disease

    Science.gov (United States)

    Sivanandam, Shanthi; Wey, Andrew; St. Louis, James

    2015-01-01

    Background Use of the Tei index has not been described to assess myocardial function before or after surgery in pediatric patients. This study was designed to evaluate the left ventricular (LV) function using the Tei index pre- and post-cardiopulmonary bypass in patients with lesion that result in a volume loaded right ventricle (RV). Methods Retrospective data on 55 patients who underwent repair of a cardiac defect were analyzed. Patients with volume overload RV (n = 15) were compared to patients without volume overload but with other cardiac defects (n = 40). We reviewed pre- and post-operative LV myocardial performance index (Tei index). Tei index was obtained from transesophageal Doppler echocardiogram. Results Patients with right heart volume overload, the mean preoperative Tei index was 0.6, with a postoperative mean decrease of 0.207 (P = 0.014). Patients without right heart volume overload, the mean preoperative Tei was 0.48 with no significant postoperative change (P = 0.82). Conclusion Pre- and post-operative transesophageal echocardiogram assessment provides an easy and quick way of evaluating LV function intra-operatively using LV Tei index. Preoperative LV Tei index was greater in the RV volume overload defects indicating diminished LV global function. This normalized in the immediate postoperative period, implying an immediate improvement in LV function. In patients without right heart volume load, consist of other cardiac defects, demonstrated no changes in the pre- and post-operative LV Tei. This implies that LV function was similar after the surgery. PMID:25849689

  10. 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

  11. Relationship between cardiac troponin-T and right ventricular Tei index in patients with hemodynamically stable pulmonary embolism: an observational study

    Directory of Open Access Journals (Sweden)

    Sava? Özsu

    2012-12-01

    Full Text Available Objective: The role of increased troponin level in risk stratification of acute pulmonary embolism (PE is well documented. However, relation between right ventricular (RV myocardial performance (Tei index and cardiac troponin-T (cTn-T has not been well investigated. The purpose of this observational prospective study was to assess the relationship between the RV Tei index and cTn-T in patients with acute normotensive PE. Methods: Thirty-eight patients with acute PE diagnosed by computed spiral tomography pulmonary angiography were enrolled to this prospective observational study. All study population underwent a comprehensive echocardiographic study including tissue Doppler imaging within first 12 hours of admission. cTn-T levels were measured on admission. Follow-up echocardiography was performed routinely at the 7th day of hospitalization. Echocardiographic evaluation was repeated at 90 days in patients with insufficient improvement of RV Tei index. The difference between the baseline and follow-up data was analyzed using the paired sample t-test or Wilcoxon test according to normality of distribution.Results: The mean of the RV Tei index was 0.46±0.14 and the mean systolic pulmonary artery pressure (sPAP was 40±20 mmHg. Increased cTn-T level was detected in 37% of the patients (normal value 0.01< ng/mL. Significant correlations were observed between RV Tei index and sPAP with cTn-T levels (r=0.467 and r=0.468, p<0.001, respectively. In logistic regression analysis, RV Tei index was associated with positive cTn-T values (OR-136, 95% CI: 1.3-14657, p=0.039. After the anticoagulant treatment, RV Tei index and sPAP were significantly improved. Conclusion: RV Tei index is frequently impaired in patients with acute PE and a significant recovery is seen after the treatment. Therefore, RV Tei index may be used both the diagnosis of RV dysfunction and the assessment of treatment effectiveness. RV Tei index is may predict myocardial injury in PE.

  12. Using TEI, CMDI and ISOcat in CLARIN-DK

    DEFF Research Database (Denmark)

    Hansen, Dorte Haltrup; Offersgaard, Lene

    2014-01-01

    This paper presents the challenges and issues encountered in the conversion of TEI header metadata into the CMDI format. The work is carried out in the Danish research infrastructure, CLARIN-DK, in order to enable the exchange of language resources nationally as well as internationally, in particular with other partners of CLARIN ERIC. The paper describes the task of converting an existing TEI specification applied to all the text resources deposited in DK-CLARIN. During the task we have tried to reuse and share CMDI profiles and components in the CLARIN Component Registry, as well as linking the CMDI components and elements to the relevant data categories in the ISOcat Data Category Registry. The conversion of the existing metadata into the CMDI format turned out not to be a trivial task and the experience and insights gained from this work have resulted in a proposal for a work flow for future use. We also present a core TEI header metadata set.

  13. Welcome to the TEI’10 Proceedings

    DEFF Research Database (Denmark)

    Pederson, Thomas; Shaer, Orit

    2010-01-01

    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.

  14. Position Estimation Using the Image Derivative

    Directory of Open Access Journals (Sweden)

    Daniele Mortari

    2015-07-01

    Full Text Available This article describes an image processing algorithm to identify the size and shape of a spherical reflecting celestial body prominently depicted in images taken from a spacecraft with an optical camera, with the purpose of estimating the relative distance between target and observer in magnitude and direction. The approach is based on the fact that in such images, the pixels belonging to the target’s hard edge have the highest values of the image derivative; therefore, they are easily recognizable when the image is processed with a gradient filter. Eventual extraneous points polluting the dataset (outliers are eliminated by two methods applied in sequence. The target center and radius are estimated by non-linear least squares using circular sigmoid functions. The proposed image processing has been applied to real and synthetic Moon images. An error analysis is also performed to determine the performance of the proposed method.

  15. Doppler Effect

    Science.gov (United States)

    Mrs. Brown

    2010-10-26

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

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

    Science.gov (United States)

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

    2012-01-01

    Background: Sickle-cell disease (SCD) is an inherited hemoglobin childhood disorder, frequently complicated by pulmonary hypertension and cardiac involvement. Cardiovascular events and complications are the leading cause of mortality and morbidity in patients with SCD. Tissue Doppler imaging and the myocardial performance index (Tei index), are simple indices for the assessment of the cardiac function. The purpose of this study was to assess the left ventricular function in children with SCD. Methods: Sixty-four patients with SCD (mean age = 11.7 ± 5.5 years) were compared with 50 age-matched healthy controls (mean age = 11.2 ± 5.20 years). Myocardial wall motion velocities at the lateral mitral annulus and the junction between the medial mitral annulus and the interventricular septum were assessed during systole (Sa), early diastole (Ea), and late diastole (Aa) through a four-chamber view using pulsed Doppler echocardiography. The ejection fraction and shortening fraction were estimated. The Tei index was estimated via tissue Doppler echocardiography. Results: The results showed that Ea and Aa velocity in the mitral annulus and interventricular septum had no difference between the patients and controls (p value > 0.05), and nor was there any difference between the two groups as regards the Tei index, Ea/Aa, ejection fraction, and shortening fraction (p value > 0.05). Sam wave velocity, however, had a significant difference between the two groups (p value < 0.038). Conclusion: The Tei index is a sensitive indicator for the cardiac function in chronic diseases and the right ventricular function in some disorders such as SCD. PMID:23304178

  17. Doppler echocardiography

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, N.C.

    1985-01-01

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

  18. Doppler echocardiography

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Pilakouta, Mirofora

    2011-01-01

    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 ...

  20. Basic doppler echocardiography

    Energy Technology Data Exchange (ETDEWEB)

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

    1986-01-01

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

  1. Basic doppler echocardiography

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  3. Process' standardization and change management in higher education. The case of TEI of Athens

    Science.gov (United States)

    Chalaris, Ioannis; Chalaris, Manolis; Gritzalis, Stefanos; Belsis, Petros

    2015-02-01

    The establishment of mature operational procedures and the effort of standardizing and certifying these procedures is a particularly arduous and demanding task which requires strong commitment from management to the existing objectives, administrative stability and continuity, availability of resources, an adequate implementation team with support from all stakeholders and of course great tolerance until tangible results of the investment are shown. Ensuring these conditions, particularly in times of economic crisis, is an extremely difficult task for large organizations such as TEI of Athens where there is heterogeneity in personnel and changes in the administrative hierarchy arise plethora of additional difficulties and require an effective change management. In this work we depict the path of standardization and certification of administrative functions of TEI of Athens, with emphasis on difficulties encountered and how to address them and in particular issues of change management and the culture related to this effort. The requirement for infrastructure needed to be maintained in processes and tools process & strategic management is embodied, in order to evolve mechanisms for continuous improvement processes and storage / recovery of the resulting knowledge. The work concludes with a general design of a road map of internal audit and continuous improvement processes for a large institution of higher education.

  4. The Training Evaluation Inventory (TEI)--Evaluation of Training Design and Measurement of Training Outcomes for Predicting Training Success

    Science.gov (United States)

    Ritzmann, Sandrina; Hagemann, Vera; Kluge, Annette

    2014-01-01

    Training evaluation in research and organisational contexts is vital to ensure informed decisions regarding the value of training. The present study describes the development of a valid and reliable training evaluation inventory (TEI), as it does not exist so far. The objectives were a) to construct an instrument that is theoretically and…

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

    Directory of Open Access Journals (Sweden)

    Kaveh Mousavi Kani

    2011-04-01

    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.

  6. 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)

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

    Full Text Available 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.

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

    CERN Document Server

    Pilakouta, Mirofora

    2011-01-01

    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

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

    Directory of Open Access Journals (Sweden)

    Cláudio Roberto Vieira Braga

    2009-11-01

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

  9. Off-design performance prediction of centrifugal pumps by using TEIS model and two-zone model

    International Nuclear Information System (INIS)

    In this study, an off-design performance prediction program for centrifugal pumps is developed. To estimate the losses in an impeller flow passage, two-zone model and Two-Element In Series(TEIS) model are used. At impeller exit, the mixing process occurs with an increase in entropy. In two-zone model, there are both primary zone and secondary zone for an isentropic core flow and an average of all non-isentropic stream tubes respectively. The level of the core flow diffusion in an impeller was calculated by using TEIS model. While internal losses in an impeller are automatically estimated by using the above models, some empirical correlations for estimating external losses, for example, disk friction loss, recirculation loss and leakage loss are used. In order to analyze the vane less diffuser flow, the momentum equations for the radial and tangential directions are used and solved together with continuity and energy equations

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

    Science.gov (United States)

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

    2009-05-01

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

  11. Laser Doppler Velocimetry Workshop

    Science.gov (United States)

    Owen, R. B.

    1979-01-01

    The potential of laser Doppler velocimetry as a technique for use in mapping flows in the several fluid systems under development for doing research on low-gravity processes, is investigated. Laser Doppler velocimetry techniques, equipment, and applications are summarized.

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

    Science.gov (United States)

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

    2013-08-01

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

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

    Directory of Open Access Journals (Sweden)

    MARIA REGINA BUENO FRANCO

    2009-07-01

    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.

  14. Resonant Doppler velocimeter

    Science.gov (United States)

    Miles, R. B.

    1975-01-01

    Narrow linewidth tunable lasers augur a new kind of laser Doppler velocimetry employing resonant absorption and fluorescence from trace atomic species rather than scattering from particles. This technique may provide better turbulence and small volume information than present velocimetry.

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

    Science.gov (United States)

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

    2015-02-01

    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

  16. VALORACIÓN DE PREFERENCIAS SOCIALES POR UNA ALTERNATIVA DE REGENERACIÓN DEL LITORAL FRENTE A UN PUERTO DEPORTIVO EN TEIS (VIGO

    Directory of Open Access Journals (Sweden)

    ROI DUR\\u00C1N MEDRA\\u00D1O

    2009-01-01

    disposición al pago (DAP o variación compensatoria de los residentes por un plan de regeneración del litoral frente al proyecto de ampliación de un puerto deportivo en Punta Lagoa en Teis (Vigo. Para el análisis de las respuestas se empleó un modelo paramétrico y uno no paramétrico, que no precisa asumir ninguna forma funcional de la distribución de la disposición al pago. Las estimaciones obtenidas muestran una DAP de 48 /hogar y de 34 /hogar, respectivamente. De estos resultados se deriva que el plan de regeneración del litoral llevaría consigo una ganancia de bienestar social respecto de la ampliación del puerto deportivo o, lo que es lo mismo, que existe un coste social asociado a este último. Al mismo tiempo, a la luz de los resultados y ante las ventajas que ofrece el estimador Turnbull, se recomienda un mayor empleo de los métodos no paramétricos para obtener estimadores a partir de datos de valoración contingente.

  17. Analysis of dust samples from the Middle East using high-density resequencing micro-array RPM-TEI

    Science.gov (United States)

    Leski, T. A.; Gregory, M. J.; Malanoski, A. P.; Smith, J. P.; Glaven, R. H.; Wang, Z.; Stenger, D. A.; Lin, B.

    2010-04-01

    A previously developed resequencing microarray, "Tropical and Emerging Infections (RPM-TEI v.1.0 chip)", designed to identify and discriminate between tropical diseases and other potential biothreat agents, their near-neighbor species, and/or potential confounders, was used to characterize the microbes present in the silt/clay fraction of surface soils and airborne dust collected from the Middle East. Local populations and U.S. military personnel deployed to the Middle East are regularly subjected to high levels of airborne desert dust containing a significant fraction of inhalable particles and some portion require clinical aid. Not all of the clinical symptoms can be directly attributed to the physical action of material in the human respiratory tract. To better understand the potential health effects of the airborne dust, the composition of the microbial communities associated with surface soil and/or airborne dust (air filter) samples from 19 different sites in Iraq and Kuwait was identified using RPM-TEI v.1.0. Results indicated that several microorganisms including a class of rapidly growing Mycobacterium, Bacillus, Brucella, Clostridium and Coxiella burnetti, were present in the samples. The presence of these organisms in the surface soils and the inhalable fraction of airborne dust analyzed may pose a human health risk and warrants further investigation. Better understanding of the factors influencing the composition of these microbial communities is important to address questions related to human health and is critical to achieving Force Health Protection for the Warfighter operating in the Middle East, Afghanistan, North Africa and other arid regions.

  18. Steerable Doppler transducer probes

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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

    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.

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

    OpenAIRE

    Begoña Simal

    2010-01-01

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

  1. The effect of a synthetic 7-thiaprostaglandin E1 derivative, TEI-6122, on monocyte chemoattractant protein-1 induced chemotaxis in THP-1 cells.

    OpenAIRE

    Tanaka, H.; Minoshima, T.; Endo, N.

    1995-01-01

    1 The ability of various prostaglandins (PGs) to inhibit monocyte chemotaxis induced by monocyte chemoattractant protein-1 (MCP-1) was investigated with a human monocytic leukaemia cell line, THP-1. Moreover, to investigate the mechanism of the inhibitory action of PGs the involvement of either intracellular adenosine 3': 5'-cyclic monosphosphate (cyclic AMP) accumulation or intracellular Ca2+ mobilization was studied. 2 TEI-6122, a synthetic 7-thia-PGE1 derivative, inhibited chemotaxis of TH...

  2. 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.)

  3. Laser Doppler projection tomography.

    Science.gov (United States)

    Zeng, Yaguang; Xiong, Ke; Lu, Xuanlong; Feng, Guanping; Han, Dingan; Wu, Jing

    2014-02-15

    We propose a laser Doppler projection tomography (LDPT) method to obtain visualization of three-dimensional (3D) flowing structures. With LDPT, the flowing signal is extracted by a modified laser Doppler method, and the 3D flowing image is reconstructed by the filtered backprojection algorithm. Phantom experiments are performed to demonstrate that LDPT is able to obtain 3D flowing structure with higher signal-to-noise ratio and spatial resolution. Our experiment results display its potentially useful application to develop 3D label-free optical angiography for the circulation system of live small animal models or microfluidic experiments. PMID:24562237

  4. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

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

  5. Doppler ion program description

    Energy Technology Data Exchange (ETDEWEB)

    Henline, P.

    1980-12-01

    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.

  6. Doppler-musical instrument

    International Nuclear Information System (INIS)

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

  7. Laser Doppler imaging, revisited

    OpenAIRE

    Atlan, Michael; Gross, Michel

    2006-01-01

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

  8. Photonic doppler velocimetry

    International Nuclear Information System (INIS)

    We are developing a novel fiber-optic approach to laser Doppler velocimetry as a diagnostic for high explosives tests. Using hardware that was originally developed for the telecommunications industry, we are able to measure surface velocities ranging from centimeters per second to kilometers per second. Laboratory measurements and field trials have shown excellent agreement with other diagnostics

  9. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

    Evans, David H; Jensen, JØrgen Arendt

    2011-01-01

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

  10. 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.

  11. Holographic laser Doppler ophthalmoscopy

    OpenAIRE

    Simonutti, Manuel; Paques, Michel; Sahel, José-Alain; Gross, Michel; Samson, Benjamin; Magnain, Caroline; Atlan, Michael

    2010-01-01

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

  12. Laser double Doppler flowmeter

    Science.gov (United States)

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

    2014-05-01

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

  13. Automated measurement of fetal myocardial performance index in ultrasound Doppler waveforms

    Science.gov (United States)

    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

    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.

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

    CERN Document Server

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

    2012-01-01

    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...

  15. 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

  16. Laser Doppler velocimetry primer

    Science.gov (United States)

    Bachalo, William D.

    1985-01-01

    Advanced research in experimental fluid dynamics required a familiarity with sophisticated measurement techniques. In some cases, the development and application of new techniques is required for difficult measurements. Optical methods and in particular, the laser Doppler velocimeter (LDV) are now recognized as the most reliable means for performing measurements in complex turbulent flows. And such, the experimental fluid dynamicist should be familiar with the principles of operation of the method and the details associated with its application. Thus, the goals of this primer are to efficiently transmit the basic concepts of the LDV method to potential users and to provide references that describe the specific areas in greater detail.

  17. 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

  18. Laser Doppler Imaging of Microflow

    CERN Document Server

    Gross, Michel; Leng, Jacques

    2013-01-01

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

  19. OTIMIZAÇÃO DA ETAPA DE ISOLAMENTO DOS COMPOSTOS VOLÁTEIS DE MEL PARA ANÁLISE POR CROMATOGRAFIA GASOSA

    Directory of Open Access Journals (Sweden)

    DEBORAH H. M. BASTOS

    2009-07-01

    Full Text Available

    O presente trabalho teve por objetivo desenvolver e detalhar uma metodologia de isolamento de compostos voláteis de mel de laranja, utilizando técnica de concentração do headspace e processo de otimização do tempo de captura e do solvente utilizado por meio de métodos sensoriais e instrumentais. Os voláteis foram capturados em polimero Porapak-Q, com tempos de captura variando entre 2 e 4 horas, utilizando-se acetona e hexano para sua desorção. Uma equipe sensorial treinada, composta por oito julgadores selecionados com base em poder discriminativo, repetibilidade e consenso nos julgamentos, avaliou a intensidade de aroma característico de mel em cada um dos isolados obtidos. Realizou-se análise cromatográfica em cada uma das fiações isoladas e o número de picos obtidos foi computado. Análise de variância univariada (ANOVA dos dados sensoriais indicou a acetona como o melhor solvente para eluição dos compostos capturados no polímero poroso e o tempo de captura de 3 horas suficiente para se obter um isolado, apresentando intensidade moderada de aroma característico de mel. Os dados instrumentais confirmaram os resultados obtidos pela análise sensorial dos isolados.

  20. Visualizing the Doppler Effect

    Directory of Open Access Journals (Sweden)

    Marcos H. Giménez

    2008-01-01

    Full Text Available The development of Information and Communication Technologies suggests some spectacular changes in the methods used for teaching scientific subjects. Nowadays, the development of software and hardware makes it possible to simulate processes as close to reality as we want. However, when we are trying to explain some complex physical processes, it is better to simplify the problem under study using simplified pictures of the total process by eliminating some elements that make it difficult to understand this process. In this work we focus our attention on the Doppler effect which requires the space-time visualization that is very difficult to obtain using the traditional teaching resources. We have designed digital simulations as a complement of the theoretical explanation in order to help students understand this phenomenon.

  1. Dual-Doppler Feasibility Study

    Science.gov (United States)

    Huddleston, Lisa L.

    2012-01-01

    When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any radar geometry issues at the NWS MLB radar, such as the "cone of silence" or beam blockage. In the event of a radar outage at one of the sites, the multi-radar algorithms would provide continuing coverage of the area through use of the data from the remaining operational radar sites. There are several options to collect, edit, synthesize and display dual-Doppler data sets. These options include commercial packages available for purchase and a variety of freeware packages available from the National Center for Atmospheric Research (NCAR) for processing raw radar data. However, evaluation of the freeware packages revealed that they do not have sufficient documentation and configuration control to be certified for 45 SW use. Additionally, a TI data line must be installed/leased from the NWS MLB office and CCAFS to enable the receipt of NWS MLB raw radar data to use in the dual-Doppler synthesis. Integration of the TI data line into the Eastern Range infrastructure that will meet the security requirements necessary for 45 SW use is time-consuming and costly. Overall evaluation indicates that establishment of the dual-Doppler capability using the existing operational radar systems is desirable and feasible with no technical concerns. Installation of such a system represents a significant enhancement to forecasting capabilities at the 45 WS and at NWS MLB. However, data security and cost considerations must be evaluated in light of current budgetary constraints. In any case, gaining the dual-Doppler capability will provide opportunities for better visualization of the wind field and better forecasting of the onset of convection and severe weather events to support space launch operations at KSC and CCAFS.

  2. Doppler characteristics of sea clutter.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2010-06-01

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

  3. Glare Spot Phase Doppler Anemometry

    OpenAIRE

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

    2006-01-01

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

  4. Laser Doppler Imaging of Microflow

    OpenAIRE

    Gross, Michel; Atlan, Michael; Leng, Jacques

    2006-01-01

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

  5. Testing of Doppler Ultrasound Systems

    OpenAIRE

    Walker, Andrew

    2009-01-01

    Blood and tissue velocities are measured and analyzed in cardiac, vascular, and other applications of diagnostic ultrasound. Errors in system performance might give invalid measurements. We developed two moving string test targets and a rotating cylinder phantom (Doppler phantoms) to characterize Doppler ultrasound systems. These phantoms were initially used to measure such variables as sample volume dimensions, location of the sample volume, and the performance of the spectral analysis. Late...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-15

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

  7. High Resolution Doppler Lidar

    Science.gov (United States)

    1996-01-01

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

  8. Adaptive Spectral Doppler Estimation

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas

    2009-01-01

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

  9. Laser Doppler anemometry

    Science.gov (United States)

    Johnson, Dennis A.

    1989-01-01

    The application of laser Doppler anemometry (LDA) to compressible flows is discussed. Specifically, burst-counter and dual-beam LDA systems are addressed. Much has been accomplished with LDA in compressible flows despite the difficulties posed by the high speeds and additionally by the rapid spatial changes in speed or flow direction. The successful application of the technique is difficult because the signal to noise ratios (SNRs) are fairly low even under the best of conditions and highly variable because of variations in particle size and particle location with the sensing volume. The available signal processing is not very effective in discarding signals that are too noisy to provide an accurate velocity measurement. The temptation is to work with particles which are too large to adequately follow the flow but which provide cleaner signals due to increased scattering intensities. For the data to have credibility, some check on the particle response must be made for a given facility and LDA system. The capability, if developed, of being able to determine the size of each particle upon which a measurement is based and the SNR of the corresponding signal burst would be extremely valuable in reducing much of the uncertainty now present in LDA compressible flow measurements.

  10. 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)

    Shiyuan LIU

    2009-05-01

    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.

  11. 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)

    Gail Falkingham

    2005-04-01

    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.

  12. Doppler echocardiography in pediatric cardiology

    International Nuclear Information System (INIS)

    Congenital heart disease encompasses abnormalities in cardiac development which generally have in common either valve stenoses or connections between chambers or great vessels. Usually, abnormalities of intracardiac anatomy, and often, abnormalities of great vessel anatomy, can be unraveled by two-dimensional echocardiography. However, echocardiography offers little information regarding flow characteristics in the various congenital lesions. Addition of the Doppler principle, particularly when combined with the two-dimensional examination, can characterize the source of a flow disturbance, quantify gradients across a site of obstruction, and quantify flow volume across sites where flow is nonturbulent. These features make Doppler echocardiography unique for noninvasive accurate evaluation of children and adults with various forms of congenital heart disease. In this report, the authors discuss some of the present uses of Doppler echocardiography in congenital heart disease. Application of this technique requires greater understanding of certain physics principles than does routine echocardiography

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

    Science.gov (United States)

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

    2009-02-01

    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.

  14. 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)

  15. Reverse Doppler Effect of Sound

    OpenAIRE

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

    2009-01-01

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

  16. Diode-Laser Doppler Velocimeter

    Science.gov (United States)

    Getzer, Gregory J.

    1989-01-01

    Diode-laser Doppler velocimeter measures nonintrusively flow of incompressible fluid in narrow tube. New velocimeter rugged, compact, and competitive in cost. Includes three-section optical head mounted on tube containing flow. In slightly different version, beam splitter and mirror used to split laser beam into two beams.

  17. The micro-doppler effect in radar

    CERN Document Server

    Chen, Victor

    2011-01-01

    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

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

    Directory of Open Access Journals (Sweden)

    Begoña Simal

    2010-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Begoña Simal

    2010-03-01

    Full Text Available

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

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

    Science.gov (United States)

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

    2015-02-01

    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

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

    Directory of Open Access Journals (Sweden)

    Márcio Martins Machado

    2004-10-01

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

  2. Luminosity Dependence and Search Doppler

    Science.gov (United States)

    VanParadijs, Johannes A.

    1998-01-01

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

  3. Doppler tomography in fusion plasmas and astrophysics

    DEFF Research Database (Denmark)

    Salewski, Mirko; Geiger, B.

    2015-01-01

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

  4. Duplex Doppler evaluation of breast masses

    International Nuclear Information System (INIS)

    The purposes of this study are to evaluate the sonographic features of breast massees to find the value of color Doppler studies on the initialexaminations. Patients who were diagnosed as breast masses by the clinical history and ultrasound examination were studied. Among them, 22 patients underwent follow-up studiesincluding color Doppler imaging. We evaluated the size, shape and echogenicity of the mass.

  5. Photodynamic effects in laser Doppler anemometry

    International Nuclear Information System (INIS)

    Photodynamic effects were observed for the first time in laser Doppler anemometry: the Doppler frequency shift of light scattered by a particle was found to depend on the action of probe light beams on this particle. (laser applications and other topics in quantum electronics)

  6. Microwave Doppler radar in unobtrusive health monitoring

    Science.gov (United States)

    Silva Girão, P.; Postolache, O.; Postolache, G.; Ramos, P. M.; Dias Pereira, J. M.

    2015-02-01

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

  7. Signal validation in laser-Doppler velocimetry

    International Nuclear Information System (INIS)

    Simple models are applied to gain insight into signal validation in laser-Doppler velocimetry and its effects on transit-time broadening. The predictions obtained are compared with measurements of decaying turbulence behind a grid using two techniques. Turbulence levels down to 0.04 percent were measured, a tenfold improvement over previously reported laser-Doppler measurements. 11 references

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

    DEFF Research Database (Denmark)

    Christensen, Anders Nymark; Reichkendler, Michala H.

    2014-01-01

    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 (Km) from dynamic [18F]-FDG PET scans of the thigh. Our objective was to obtain nonbiased, low-variance Km values without blood sampling.

  9. OTIMIZAÇÃO DAS CONDIÇÕES DE ISOLAMENTO DOS VOLÁTEIS DO HEADSPACE DO MARACUJÁ AMARELO POR CONCENTRAÇÃO A VÁCUO EM PORAPAK Q

    Directory of Open Access Journals (Sweden)

    K. A. JALES

    2009-01-01

    Full Text Available

    O presente trabalho teve por objetivo estabelecer as melhores condições de isolamento dos voláteis de maracujá amarelo pela técnica de concentração do headspace a vácuo no polímero Porapak Q, bem como determinar o solvente mais apropriado para eluição dos voláteis adsorvidos no polímero. Foram testados três solventes: hexano, diclorometano e acetona. Após a escolha do solvente, foi realizado um delineamento composto central, variando-se a massa de suco integral de maracujá de 2 a 300g e o tempo de isolamento de 10 a 240 minutos. Os isolados foram analisados por cromatografia gasosa de alta resolução e análise sensorial. As melhores condições foram aquelas que produziram um isolado com maior número de picos, maior área total dos picos e maior intensidade de aroma característico de maracujá. O diclorometano foi o solvente que apresentou a eluição mais eficiente. As condições ótimas de isolamento foram 150g de suco sem sementes sob 240 min de vácuo.

  10. 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

  11. Endarterectomía carotídea: monitoreo intraoperatorio con Doppler transcraneano

    Scientific Electronic Library Online (English)

    Roberto, Herrera; Héctor, Rojas; José Luis, Ledesma; Julián, Pastore; Andrea, Uez Pata.

    2007-09-01

    Full Text Available [...] Abstract in english Objective: To evaluate the usefullness of intraoperative monitoring with transcranial doppler during the carotid endarterectomy. Description: In the last two years we performed 15 carotid endarterectomies with transcranial doppler intraoperative monitoring. In all cases we didn’t use a shunt during [...] the procedure based on the monitoring results. Results: All patients recovered without any neurological deficit. Conclusions: Intraoperatve monitoring with transcranial doppler seems to be a good method to determinate the use or not of a shunt during the procedure.

  12. Lorentz Covariant Theory of Precise Doppler Measurements

    CERN Document Server

    Kopeikin, S M

    1999-01-01

    The Lorentz covariant theory of precise Doppler measurements (PDM) based on the retarded Liénard-Wiechert solution of the Einstein equations is described. An exact solution of equations of light propagation in the field of arbitrary moving bodies, which drastically extends the range of applicability of the new theory of PDM, is obtained. An explicit formula for the gravitational shift of frequency is given in analytic form. The limiting cases of the Doppler observations in gravitational lensing and of the spacecraft's Doppler tracking are described in more detail. We also present the post-Newtonian theory of the PDM developed for searching relativistic effects in close optical binaries and massive planetary systems.

  13. Color doppler and power doppler ultrasonography in renal transplant recipients with cytomegalovirus infection

    International Nuclear Information System (INIS)

    Objective: To investigate the features of color Doppler and Doppler ultrasonography of transplanted kidneys in patients with cytomegalovirus infections. Methods: Color Doppler and Power Doppler ultrasonography was used to examine transplanted kidneys in 36 recipients with cytomegalovirus infection. The blood flow area ratios (BFAR), the volumes, the resistive indexes (RI), the peak flow velocities in parenchymal arteries (Vmax) were measured and compared with no complication (normal) cases. Results: BFAR was lower in patients with cytomegalovirus infection than that in no complication (normal) cases (P0.05). Conclusions: The blood flows of transplanted kidneys were reduced in patients with cytomegalovirus infection. To monitor BFAR of transplanted kidneys was contributed to evaluate management effect

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

    Science.gov (United States)

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

    2012-12-01

    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

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

    Science.gov (United States)

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

    2012-12-01

    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.

  16. Anomalous Doppler effects in phononic band gaps.

    Science.gov (United States)

    Hu, Xinhua; Hang, Zhihong; Li, Jensen; Zi, Jian; Chan, C T

    2006-01-01

    Doppler effects in periodic acoustic media were studied theoretically and experimentally. Analytical formulas are derived using the Green's function formalism. We found that a far field observer cannot hear the sound inside a band gap from a stationary source, but a moving source can be heard even if the frequency is inside the gap, and the Doppler shifts can be inverted or anomalously large. PMID:16486208

  17. Applications of Doppler in the first trimester

    International Nuclear Information System (INIS)

    Fifty patients have been studied by duplex Doppler US imaging in the first trimester. In normal gestations, luteal flow, characterized by a low pulsatility index (PI), can be seen in at least one ovary. Failure to detect luteal flow indicates a nonviable pregnancy. Six ectopic pregnancies demonstrated luteal flow and extrauterine heartbeat, detected by Doppler US. High PI values in the uterine artery are seen in the first trimester. Low PI values in the uterine arteries were found in patients with trophoblastic disease

  18. Doppler Effect of Mechanical Waves and Light

    Directory of Open Access Journals (Sweden)

    Jiacai Nie

    2009-09-01

    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

  19. Laser Doppler flowmetry in microvascular surgery

    OpenAIRE

    Adrichem, L.N.A. van

    1992-01-01

    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 ...

  20. Doppler velocimeter for laser accelerated targets

    International Nuclear Information System (INIS)

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

  1. Performance testing of ultrasound Doppler equipment

    OpenAIRE

    Walker, Andrew

    2003-01-01

    Blood and tissue velocities are measured and analysed in cardiac, vascular and other applications of diagnostic ultrasound. Errors in system performance might give invalid measurements. We developed two moving string test targets (“Doppler phantoms”) to characterise ultrasound Doppler systems. These phantoms were initially used to measure such variables as sample volume dimensions, location of the sample volume, and the performance of the spectral analysis. Specific tests were done to det...

  2. Doppler tomography of accretion in binaries

    OpenAIRE

    D. Steeghs

    2003-01-01

    Since its conception, Doppler tomography has matured into a versatile and widely used tool. It exploits the information contained in the highly-structured spectral line-profiles typically observed in mass-transferring binaries. Using inversion techniques akin to medical imaging, it permits the reconstruction of Doppler maps that image the accretion flow on micro-arcsecond scales. I summarise the basic concepts behind the technique and highlight two recent results; the use of...

  3. Doppler velocimetry in cavitating media.

    Science.gov (United States)

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

    1997-01-01

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

  4. Estimation of the continuously varying Doppler effect

    Science.gov (United States)

    Nelson, D. J.; Troxell, S. J.

    2010-04-01

    There are many applications for which it is important to resolve the location and motion of a target position. For the static situation in which a target transmitter and several receivers are not in motion, the target may be completely resolved by triangulation using relative time delays estimated by several receivers at known locations. These delays are normally estimated from the location of peaks in the magnitude of the cross-correlation function. For active radars, a transmitted signal is reflected by the target, and range and radial velocity are estimated from the delay and Doppler effects on the received signal. In this process, Doppler effects are conventionally modeled as a shift in frequency, and delay and Doppler are estimated from a cross-ambiguity function (CAF) in which delay and Doppler frequency shift are assumed to be independent and approximately constant. Delay and Doppler are jointly estimated as the location of the peak magnitude of the CAF plane. We present methods for accurately estimating delay for the static case and delay and the time-varying Doppler effects for non-static models, such as the radar model.

  5. Color Doppler Ultrasound Indices in Endometriotic Cysts

    Directory of Open Access Journals (Sweden)

    Parisa Hajialioghlo

    2009-01-01

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

  6. Estimating the Doppler centroid of SAR data

    DEFF Research Database (Denmark)

    Madsen, SØren NØrvang

    1989-01-01

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

  7. Retroreflector for photonic Doppler velocimetry

    Science.gov (United States)

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

    2009-08-01

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

  8. Duplex doppler sonography in portal hypertension

    Directory of Open Access Journals (Sweden)

    Ni?iforovi? Dijana

    2007-01-01

    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. .

  9. Development of the doppler electron velocimeter: theory.

    Energy Technology Data Exchange (ETDEWEB)

    Reu, Phillip L.

    2007-03-01

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

  10. Self-mixing laser Doppler vibrometer

    Science.gov (United States)

    Scalise, Lorenzo; Paone, Nicola

    2000-05-01

    In this paper, an extremely small, simple and economic laser Doppler sensor is presented. It simply consists of a laser diode and of an optical system composed by two lenses in order to focus the laser light. The sensor is able to measure velocity and it is based on the self-mixing effect that occurs in a semiconductor laser diode when the emitted radiation is back reflected toward the cavity and then re- introduced inside. The velocity is calculated measuring the position of the frequency peak on the frequency spectrum of the intensity signal generated by the photodiode present inside the laser diode when modulated by feedback light coming from the moving scattering particles. The laser Doppler self-mixing velocimeter has been statically calibrated, using a rotating disk covered with white paper. The sensor has then been dynamically characterized using an electro-magnetic shaker and a Laser Doppler Vibrometer as reference.

  11. Color Doppler ultrasonography evaluation of amblyopia

    Directory of Open Access Journals (Sweden)

    Ece Turan-Vural

    2013-07-01

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

  12. Arm locking with Doppler estimation errors

    International Nuclear Information System (INIS)

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

  13. Rubidium Atomic Line Filtered (RALF) Doppler Velocimetry

    Science.gov (United States)

    Fajardo, Mario; Molek, Christopher; Vesely, Annamaria; Lasem Team

    2013-06-01

    We report our progress towards adapting the well-known Global Dopper Velocimetry (GDV) technique, popular in the aerodynamics community, to the order-of-magnitude higher velocities pertinent to shock experiments. In GDV, the narrow-line illumination laser is tuned to an edge of a molecular iodine absorption line; an iodine gas cell converts the Doppler shift of the reflected light to transmitted intensity. We follow the suggestion in the original 1990 patent by Komine and broaden the absorption lines of alkali metal atoms by adding a buffer gas, thereby tuning the transmission edge spectrum to match the Doppler shift (surface velocity) range of interest. We use atomic rubidium vapor cells, with 0 to 1 atmosphere pressures of molecular nitrogen buffer gas, and coin the name ``Rubidium Atomic Line Filtered'' (RALF) Doppler velocimetry. [96ABW-2013-0036

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

    OpenAIRE

    Luca Giugno; Francesca Zanier; Marco Luise

    2007-01-01

    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) estimatio...

  15. Velocity measurement by vibro-acoustic Doppler.

    Science.gov (United States)

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

    2012-04-01

    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

  16. Laser Doppler distance sensor using phase evaluation.

    Science.gov (United States)

    Günther, P; Pfister, T; Büttner, L; Czarske, J

    2009-02-16

    This paper presents a novel optical sensor which allows simultaneous measurements of axial position and tangential velocity of moving solid state objects. An extended laser Doppler velocimeter setup is used with two slightly tilted interference fringe systems. The distance to a solid state surface can be determined via a phase evaluation. The phase laser Doppler distance sensor offers a distance resolution of 150 nm and a total position uncertainty below 1 microm. Compared to conventional measurement techniques, such as triangulation, the distance resolution is independent of the lateral surface velocity. This advantage enables precise distance and shape measurements of fast rotating surfaces. PMID:19219164

  17. Rotational Doppler beaming in eclipsing binaries

    CERN Document Server

    Groot, Paul J

    2011-01-01

    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.

  18. Laser Doppler And Range Systems For Spacecraft

    Science.gov (United States)

    Kinman, P. W.; Gagliardi, R. M.

    1990-01-01

    Report discusses two types of proposed laser systems containing active transponders measuring distance (range) and line-of-sight velocity (via Doppler effect) between deep space vehicle and earth-orbiting satellite. Laser system offers diffraction advantage over microwave system. Delivers comparable power to distant receiver while using smaller transmitting and receiving antennas and less-powerful transmitter. Less subject to phase scintillations caused by passage through such inhomogeneous media as solar corona. One type of system called "incoherent" because range and Doppler measurements do not require coherence with laser carrier signals. Other type of system called "coherent" because successful operation requires coherent tracking of laser signals.

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

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

  20. Fish embryo multimodal imaging by laser Doppler digital holography

    CERN Document Server

    Verrier, Nicolas; Picart, Pascal; Gross, Michel

    2015-01-01

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

  1. Computer Vision Approach for Ultrasound Doppler Angle Estimation

    OpenAIRE

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

    2008-01-01

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

  2. Ultrasonic Doppler color in glaucoma: Concordance study

    International Nuclear Information System (INIS)

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

  3. HF Doppler Radar Observations of Geomagnetic Pulsations.

    Czech Academy of Sciences Publication Activity Database

    Fišer, Ji?í; Chum, Jaroslav

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

  4. Color Doppler US of superficial adenopathies

    International Nuclear Information System (INIS)

    Superficial lymph node are frequently involved in different diseases. Their location makes them suitable for effective assessment with high-resolution US and color Doppler has been recently suggested as a tool for increasing sensitivity in lymph node studies. Thus the author investigated the main vascular patterns detectable in abnormal superficial lymph nodes

  5. Spectroscopic observation of the rotational Doppler effect

    OpenAIRE

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

    2006-01-01

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

  6. Interface Circuit for Laser Doppler Velocimeters

    Science.gov (United States)

    Harrison, Dean R.; Brown, James L.

    1987-01-01

    New circuit displays more information to user and provides higher data-collection rates. Interface circuit facilitates coupling of laser-Doppler-velocimeter outputs to computer for analysis. Enables user to select variety of intermediate data-processing options, including clock frequency, coincidence channel combinations, coincidence times, dead times, digital or analog output, and channels to be analyzed.

  7. Pulsed Doppler lidar at QinetiQ

    Science.gov (United States)

    Pearson, Guy N.

    2004-12-01

    Recent developments in pulsed Doppler lidar technology for range-resolved aerosol and hard-target imaging applications are presented. Systems based upon CO2 and fiber-optic technologies at wavelengths of 10.6 ?m and 1.5 ?m respectively are described. Data are presented showing aspects of system and component development as well as recent field deployments.

  8. Atmospheric laser Doppler velocimetry - An overview

    Science.gov (United States)

    Bilbro, J. W.

    1980-01-01

    Research, development, and application of atmospheric laser Doppler velocimetry are overviewed. Consideration is given to operation principles of CO2 heterodyne systems. Global wind, pollution, V/STOL flow, and true airspeed measurements are outlined. Wind energy, dust devils, water spouts, tornadoes, and aircraft wake vortices are covered.

  9. Cross-frequency Doppler sensitive signal processing

    Science.gov (United States)

    Wagstaff, Ronald A.

    2005-04-01

    When there is relative motion between an acoustic source and a receiver, a signal can be Doppler shifted in frequency and enter or leave the processing bins of the conventional signal processor. The amount of the shift is determined by the frequency and the rate of change in the distance between the source and the receiver. This frequency Doppler shifting can cause severe reductions in the processors performance. Special cross-frequency signal processing algorithms have recently been developed to mitigate the effects of Doppler. They do this by using calculation paths that cut across frequency bins in order to follow signals during frequency shifting. Cross-frequency spectral grams of a fast-flying sound source were compared to conventional grams, to evaluate the performance of this new signal processing method. The Doppler shifts in the data ranged up to 70 contiguous frequency bins. The resulting cross-frequency grams showed that three paths provided small to no improvement. Four paths showed improvements for either up-frequency or down-frequency shifting, but not for both. Two paths showed substantial improvement for both up-frequency and down-frequency shifting. The cross-frequency paths will be defined, and comparisons between conventional and cross-frequency grams will be presented. [Work supported by Miltec Corporation.

  10. 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

  11. Design of a Doppler reflectometer for KSTAR

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-15

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

  12. Transcranial Doppler sonography in familial hemiplegic migraine

    International Nuclear Information System (INIS)

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

  13. 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.)

  14. Color Doppler US of the penis

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

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

  15. Design of a Doppler reflectometer for KSTAR.

    Science.gov (United States)

    Lee, K D; Nam, Y U; Seo, Seong-Heon; Kim, Y S

    2014-11-01

    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. PMID:25430271

  16. Transcranial Doppler sonography in familial hemiplegic migraine

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-02-01

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

  17. Laser Doppler measurement of cutaneous blood flow

    International Nuclear Information System (INIS)

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

  18. Tendon excursion measurements with colour Doppler imaging.

    Science.gov (United States)

    Buyruk, H M; Holland, W P; Snijders, C J; Laméris, J S; Hoorn, E; Stoeckart, R; Stam, H J

    1998-06-01

    We assessed the applicability of tendon excursion measurement by means of Colour Doppler Imaging (CDI) on human specimens, and also assessed the correlation between values measured by Doppler and by displacement meters. Muscles were separately connected to a mass of 1 kg with a steel wire running over a pulley. This weight moved the telescopic end of a digital displacement meter up and down during passive extension and flexion of the fingers. Excursion was measured with a pulsed multi-channel CDI scanner on the same arm. Assessment of finger tendon excursion with CDI correlated well with the mechanical micro displacement meter, the latter being considered the most accurate method in cadaver studies. PMID:9665524

  19. The observability of secondary doppler peaks

    OpenAIRE

    Hobson, Michael P.

    1996-01-01

    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.

  20. Colour Doppler ultrasound of the penis

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-01

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

  1. 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

  2. Spatial and Wavenumber Resolution of Doppler Reflectometry

    OpenAIRE

    Gusakov, Evgeniy; Surkov, Alexander

    2004-01-01

    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 squar...

  3. Doppler cooling of a Coulomb crystal

    OpenAIRE

    Morigi, Giovanna

    2001-01-01

    We study theoretically Doppler laser-cooling of a cluster of 2-level atoms confined in a linear ion trap. Using several consecutive steps of averaging we derive, from the full quantum mechanical master equation, an equation for the total mechanical energy of the one dimensional crystal, defined on a coarse-grained energy scale whose grid size is smaller than the linewidth of the electronic transition. This equation describes the cooling dynamics for an arbitrary number of io...

  4. Poincare's relativistic Doppler-Fizeau formula

    OpenAIRE

    Pierseaux, Yves

    2006-01-01

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

  5. Doppler study of cerebral arteries in hypercholesterolemia

    OpenAIRE

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

    2011-01-01

    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...

  6. Laser Doppler visualisation of the velocity field

    International Nuclear Information System (INIS)

    A method for the laser Doppler real-time visualisation of the velocity field of moving media was developed. The method is based on the optical frequency demodulation of the optical fields forming the image of the investigated cross section. The visualiser was constructed on the basis of a semiconfocal optical cavity. The results of the visualisation of the velocity field of a vortical flow in a cylindrical channel are presented. (laser applications and other topics in quantum electronics)

  7. Doppler velocimeter for laser accelerated targets

    International Nuclear Information System (INIS)

    A doppler velocimeter utilizing a spectrograph and a short-pulse laser probe is described which provides good spatial (20 ?m) and subnanosecond temporal resolution. This system has been used to measure the velocity profiles of targets ablatively accelerated to very high velocities by a high-power laser beam. In comparison to systems employing interferometric techniques, this velocimeter significantly relaxes requirements on the target surface being examined and the time resolution needed to measure velocities of rapidly accelerating surfaces

  8. Doppler-free magnetic optical activity

    OpenAIRE

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

    1980-01-01

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

  9. Sub miniaturized laser doppler velocimeter sensor

    Science.gov (United States)

    Gharib, Morteza (Inventor); Modaress, Darius (Inventor); Taugwalder, Frederic (Inventor)

    2003-01-01

    A miniaturized laser Doppler velocimeter is formed in a housing that is preferably 3 mm in diameter or less. A laser couples light to a first diffractive optical element that is formed on the fiber end. The light is coupled to a lens that also includes a diffractive optical element. The same lens is also used to collect receive light, and receives includes another diffractive optical element to collect that received light.

  10. On Doppler tracking in cosmological spacetimes

    International Nuclear Information System (INIS)

    We give a rigorous derivation of the general-relativistic formula for the two-way Doppler tracking of a spacecraft in Friedmann-LemaItre-Robertson-Walker and McVittie spacetimes. The leading order corrections of the so-determined acceleration to the Newtonian acceleration are due to special-relativistic effects and cosmological expansion. The latter, although linear in the Hubble constant, is negligible in typical applications within the solar system

  11. Single mode, extreme precision Doppler spectrographs

    OpenAIRE

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

    2012-01-01

    The 'holy grail' of exoplanet research today is the detection of an earth-like planet: a rocky planet in the habitable zone around a main-sequence star. Extremely precise Doppler spectroscopy is an indispensable tool to find and characterize earth-like planets; however, to find these planets around solar-type stars, we need nearly one order of magnitude better radial velocity (RV) precision than the best current spectrographs provide. Recent developments in astrophotonics (B...

  12. Diffractive beam splitter for laser Doppler velocimetry

    OpenAIRE

    Schmidt, J; Völkel, R.; Stork, W; Sheridan, John T.; Schwider, J.; Streibl, N.; Durst, F

    1992-01-01

    A miniaturized sensor head for the optical measurement of velocities of fluids based on laser Doppler velocimetry is demonstrated. Holographic optical elements mounted on a glass substrate are used for beam splitting and deflection. Volume holograms in dichromated gelatin exhibit good optical efficiency (75% transmission of a cascade of two holographic optical elements). With diffractive devices one can achieve achromatic behavior that makes the sensor insensitive to wavelength drifts or mode...

  13. Interferometric filter-based planar Doppler velocimetry

    OpenAIRE

    Lu, Zenghai

    2008-01-01

    This thesis describes the development of a Mach-Zehnder interferometric filter based planar Doppler velocimetry (MZI-PDV) flow measurement technique. The technique uses an entirely new optical system, an unbalanced MZI incorporating glass blocks for wavefront-matching, to replace the iodine cell currently used in conventional PDV. The free spectral range of the interferometric filter can be selected by adjusting the optical path difference of the MZI. This allows the velocity m...

  14. Radar target micro-doppler signature classification

    OpenAIRE

    Smith, G.E.

    2008-01-01

    This thesis reports on research into the field of Micro-Doppler Signature (?-DS) based radar Automatic Target Recognition (ATR) with additional contributions to general radar ATR methodology. The ?-DS based part of the research contributes to three distinct areas: time domain classification; frequency domain classification; and multiperspective ?-DS classification that includes the development of a theory for the multistatic ?-DS. The contribution to general radar ATR is the proposal of a ...

  15. An alternative stochastic doppler broadening algorithm

    International Nuclear Information System (INIS)

    The temperature dependent, ideal gas scattering kernel for heavy nuclei with pronounced resonances was developed, proved and implemented in the data processing code NJOY from which the scattering probability tables were prepared. Those tables were introduced to the well known MCNP code. The analytic solution of this scattering kernel is consistent with the Doppler Broadening method of D. E. Cullen and C. R. Weisbin. In this study we present an alternative stochastic algorithm based on MCNP subroutines which allows for Doppler broadening of the integral as well as double differential cross section. The analytical solution of the kernel is confirmed. This stochastic method is then introduced into the MCNP code by means of a rejection method, suggested originally by W. Rothenstein. The differences between the new kernel and the standard MCNP kernel are illustrated for specific resonances of U-238, Th-232, Au-197 and Hg-199. LWR unit cell calculations are performed and criticality, reaction rates and Doppler reactivity coefficients are calculated. Based on comparison with the analytical (probability S(?,?)-tables) approach it is confirmed that the stochastic algorithm gives accurate results. The differences lie within 1-2 standard deviations for all practical cases that were analyzed. (authors)

  16. Doppler Lidar for Wind Measurements on Venus

    Science.gov (United States)

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

    2010-01-01

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

  17. Laser Doppler measurement techniques for spacecraft

    Science.gov (United States)

    Kinman, Peter W.; Gagliardi, Robert M.

    1986-01-01

    Two techniques are proposed for using laser links to measure the relative radial velocity of two spacecraft. The first technique determines the relative radial velocity from a measurement of the two-way Doppler shift on a transponded radio-frequency subcarrier. The subcarrier intensity-modulates reciprocating laser beams. The second technique determines the relative radial velocity from a measurement of the two-way Doppler shift on an optical frequency carrier which is transponded between spacecraft using optical Costas loops. The first technique might be used in conjunction with noncoherent optical communications, while the second technique is compatible with coherent optical communications. The first technique simultaneously exploits the diffraction advantage of laser beams and the maturity of radio-frequency phase-locked loop technology. The second technique exploits both the diffraction advantage of laser beams and the large Doppler effect at optical frequencies. The second technique has the potential for greater accuracy; unfortunately, it is more difficult to implement since it involves optical Costas loops.

  18. Doppler sonographic findings in testicular microlithiasis

    Scientific Electronic Library Online (English)

    Selim, Serter; Sebnem, Orguc; Bilal, Gumus; Veli, Ayyildiz; Yuksel, Pabuscu.

    2008-08-01

    Full Text Available OBJECTIVE: The aim of this prospective study was to compare the resistive index (RI) values, which is a parameter of testicular parenchymal perfusion, in testicular microlithiasis (TM) cases and normal cases. MATERIALS AND METHODS: 2179 volunteers, all healthy men (17-42 years of age) from the Annua [...] l Army Reserve Officer Training Corps training camp were included in the study. A screening scrotal ultrasound was performed and all men diagnosed with TM underwent a scrotal Doppler ultrasonography scan (US). US examinations were performed for subjects with TM and without TM as a control group and RI was determined. RESULTS: 53 men with TM were identified in the 2179 US. Spectral Doppler examination was applied to 50 randomly selected cases (100 testicles) without TM and 92 testicles with TM, 39 cases (78 testicles) with bilateral and 14 cases with unilateral involvement. However, 48 normal testicles (17 bilateral and 14 unilateral) and 47 testicles with TM (15 bilateral and 17 unilateral, 10 of which were cases with bilateral TM) where flow from the centripetal artery could be obtained and analyzed were included in the statistical analysis for resistive indices. There was no significant difference regarding the RI and spectral examinations between subjects with and without TM. An interesting finding was the twinkling artifact observed in three cases. CONCLUSION: Microliths did not alter the RI values and thus had no influence on testicular perfusion on Doppler US examination.

  19. Doppler sonographic findings in testicular microlithiasis

    Directory of Open Access Journals (Sweden)

    Selim Serter

    2008-08-01

    Full Text Available OBJECTIVE: The aim of this prospective study was to compare the resistive index (RI values, which is a parameter of testicular parenchymal perfusion, in testicular microlithiasis (TM cases and normal cases. MATERIALS AND METHODS: 2179 volunteers, all healthy men (17-42 years of age from the Annual Army Reserve Officer Training Corps training camp were included in the study. A screening scrotal ultrasound was performed and all men diagnosed with TM underwent a scrotal Doppler ultrasonography scan (US. US examinations were performed for subjects with TM and without TM as a control group and RI was determined. RESULTS: 53 men with TM were identified in the 2179 US. Spectral Doppler examination was applied to 50 randomly selected cases (100 testicles without TM and 92 testicles with TM, 39 cases (78 testicles with bilateral and 14 cases with unilateral involvement. However, 48 normal testicles (17 bilateral and 14 unilateral and 47 testicles with TM (15 bilateral and 17 unilateral, 10 of which were cases with bilateral TM where flow from the centripetal artery could be obtained and analyzed were included in the statistical analysis for resistive indices. There was no significant difference regarding the RI and spectral examinations between subjects with and without TM. An interesting finding was the twinkling artifact observed in three cases. CONCLUSION: Microliths did not alter the RI values and thus had no influence on testicular perfusion on Doppler US examination.

  20. Computer vision approach for ultrasound Doppler angle estimation.

    Science.gov (United States)

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

    2009-12-01

    Doppler ultrasound is an important noninvasive diagnostic tool for cardiovascular diseases. Modern ultrasound imaging systems utilize spectral Doppler techniques for quantitative evaluation of blood flow velocities, and these measurements play a crucial rule in the diagnosis and grading of arterial stenosis. One drawback of Doppler-based blood flow quantification is that the operator has to manually specify the angle between the Doppler ultrasound beam and the vessel orientation, which is called the Doppler angle, in order to calculate flow velocities. In this paper, we will describe a computer vision approach to automate the Doppler angle estimation. Our approach starts with the segmentation of blood vessels in ultrasound color Doppler images. The segmentation step is followed by an estimation technique for the Doppler angle based on a skeleton representation of the segmented vessel. We conducted preliminary clinical experiments to evaluate the agreement between the expert operator's angle specification and the new automated method. Statistical regression analysis showed strong agreement between the manual and automated methods. We hypothesize that the automation of the Doppler angle will enhance the workflow of the ultrasound Doppler exam and achieve more standardized clinical outcome. PMID:18488268

  1. Doppler echocardiography in elderly patients with ejection systolic murmurs.

    OpenAIRE

    McKillop, G. M.; Stewart, D A; Burns, J. M.; Ballantyne, D.

    1991-01-01

    Thirty-nine elderly patients, mean age 77 years (range 65 to 96), with ejection systolic murmurs were studied to evaluate the functional significance of these murmurs. Subjects were evaluated clinically, by 2-D echocardiography, and by a full Doppler echocardiography study. Good quality Doppler signals were obtained in 35 subjects. Mitral regurgitation was found to be the only significant valvular lesion in 6 patients (17%). Doppler gradients in systole across the aortic valve were less than ...

  2. Is tissue Doppler echocardiography the Holy Grail for the intensivist?

    OpenAIRE

    Poelaert, Jan; Roosens, Carl

    2007-01-01

    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...

  3. Doppler Uterine Artery Flow Velocimetry in Prediction of Preterm Labor

    OpenAIRE

    Mahyar Mohammadi Fard; Alireza Mirgholami; Masoud Pezeshki Rad

    2009-01-01

    "nIntroduction: To evaluate the role of Doppler waveforms of the uterine vessels in predicting preterm labor. "nMaterials and Methods: This was a retrospective analysis of the uterine artery Doppler findings of 28 15-25 week singleton pregnancies with a spontaneous preterm labor were compared to 326 pregnancies delivered at term. 354 women who presented to our medical center from April 20, 2008 to November 20, 2008 were enrolled in the study. Pulsed-wave Doppler measurements were ma...

  4. Doppler radar wind field retrieval over the Po Valley

    OpenAIRE

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

    2006-01-01

    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...

  5. 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)

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

    Directory of Open Access Journals (Sweden)

    Luca Giugno

    2007-05-01

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

  7. Christian Doppler is 200 years young.

    Science.gov (United States)

    Bollinger, Alfred; Partsch, Hugo

    2003-11-01

    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

  8. Observation of sub-Doppler absorption in the /Lambda-type three-level Doppler-broadened cesium system

    OpenAIRE

    Wang, Junmin; Wang, Yanhua; Yan, Shubin; LIU, TAO; Zhang, Tiancai

    2003-01-01

    Thanks to the atomic coherence in coupling laser driven atomic system, sub-Doppler absorption has been observed in Doppler-broadened cesium vapor cell via the /Lambda-type three-level scheme. The linewidth of the sub-Doppler absorption peak become narrower while the frequency detuning of coupling laser increases. The results are in agreement with the theoretical prediction by G. Vemuri et al.[PRA,Vol.53(1996) p.2842].

  9. Tecnología Doppler y movimientos respiratorios fetales

    Scientific Electronic Library Online (English)

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

    2008-03-01

    Full Text Available 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.

  10. Accuracy and precision in photonic Doppler velocimetry

    International Nuclear Information System (INIS)

    While photonic Doppler velocimetry (PDV) is becoming a common diagnostic in dynamic compression research, its limiting accuracy and precision are not well understood. Velocity resolution is known to be inversely proportional to the time resolution, but resolution estimates differ by one to two orders of magnitude. Furthermore, resolution varies with the number of recorded signals and how these signals are analyzed. Numerical simulations reveal factors that affect accuracy and precision in PDV, and the results may be extended to a broad class of measurements. After systematic effects are eliminated, the limiting velocity uncertainty in a PDV measurement is governed by the sampling rate, the signal noise fraction, and the analysis time duration.

  11. Doppler frequency shift of sound apparatus

    Science.gov (United States)

    Schier, Walter

    2011-04-01

    A large 1-m diameter rotary table with a semicircular waveguide along its periphery is the basis of the Doppler frequency shift of sound apparatus. A "button" speaker is attached to the outer edge of the rotary table and a microphone pickup is positioned on the wall of the waveguide at its midpoint. At approximate speeds of 25 mph (11 m/s), the velocity measured from the frequency shift between the approaching and receding speaker compared to the velocity measured from the repeat sound pattern agree to within 1%. The microphone output is fed successively to our 10 computer stations.

  12. Color Doppler Ultrasonographic Features of Hashimoto's Thyroiditis

    International Nuclear Information System (INIS)

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

  13. Ambiguity resolution for satellite Doppler positioning systems

    Science.gov (United States)

    Argentiero, P.; Marini, J.

    1979-01-01

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

  14. Comparison of Triature Doppler Velocimetry and VISAR

    International Nuclear Information System (INIS)

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

  15. Comparison of Triature Doppler Velocimetry and Visar

    International Nuclear Information System (INIS)

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

  16. The Doppler and gravitational components of the cosmological redshift

    International Nuclear Information System (INIS)

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

  17. 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)

  18. High-contrast Doppler-free transmission spectroscopy

    OpenAIRE

    Svanberg, Sune; Yan, G. Y.; Duffey, T.P.; Schawlow, A. L

    1986-01-01

    By applying Doppler-free saturated absorption spectroscopy in the regime of high integrated sample absorption, high-contrast Doppler-free laser transmission signals can be obtained as demonstrated in experiments on the sodium D lines. Natural linewidth background-free signals are observed.

  19. Analysis of Doppler effect with JAERI-Fast set

    International Nuclear Information System (INIS)

    Temperature dependence of group cross sections in the JAERI-Fast set versions I, IR, II and IIR has been tested from the analysis of Doppler experiments performed with two different methods. One is Doppler reactivity measurement for the whole core of SEFOR assembly, and the other sample Doppler reactivity measurement for natural UO2 in FCA assemblies V-1, V-2, VI-1 and VI-2, ZPR-6-7, ZPR-3-47, and ZPPR-2 and 3. Doppler effects were calculated with one- and two-dimensional diffusion 1-st order perturbation code DOPP2D. The results calculated with the JAERI-Fast set versions II and IIR are in good agreement with the experimental ones. In these calculation, resonance heterogeneity effect, stainless-stell buffer effect and plate heterogeneity effect are considered, and these effects contribute significantly to Doppler effect. (auth.)

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

    CERN Document Server

    Petrova, Inna R; Latypov, Ruslan R

    2014-01-01

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

  1. Breast Discharge: Ultrasound and Doppler Evaluation

    International Nuclear Information System (INIS)

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

  2. 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

  3. Microscale Heat Conduction Models and Doppler Feedback

    Energy Technology Data Exchange (ETDEWEB)

    Hawari, Ayman I.; Ougouag, Abderrafi

    2015-01-22

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

  4. Position finding using simple Doppler sensors

    Directory of Open Access Journals (Sweden)

    S. Schelkshorn

    2007-06-01

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

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

  5. Signal Processing Schemes for Doppler Global Velocimetry

    Science.gov (United States)

    Meyers, James F.; Lee, Joseph W.; Cavone, Angelo A.

    1991-01-01

    Two schemes for processing signals obtained from the Doppler global velocimeter are described. The analog approach is a simple, real time method for obtaining an RS-170 video signal containing the normalized intensity image. Pseudo colors are added using a monochromatic frame grabber producing a standard NTSC video signal that can be monitored and/or recorded. The digital approach is more complicated, but maintains the full resolution of the acquisition cameras with the capabilities to correct the signal image for pixel sensitivity variations and to remove of background light. Prototype circuits for each scheme are described and example results from the investigation of the vortical flow field above a 75-degree delta wing presented.

  6. Parallax effects in laser Doppler spectroscopy

    International Nuclear Information System (INIS)

    Parallax effects in laser Doppler spectroscopy, associated with the variation of the scattering angle during motion of a particle through the probed volume, were investigated by a numerical simulation method based on the Mie scattering theory. It was found that, in general, the shifts of the spectral profile parameters (the average frequency, broadening, asymmetry, and kurtosis) become significant as the parallax number N??=(2/?)?? (? is the angular size of the probed volume, ? = ?d/? is the relative particle diameter) increases. The anomalous ranges of the parameters of the particle and of the optical system, in which marked distortions (such as the polymodal nature and the splitting of the spectral profile) are observed even for a low parallax number (N?? || 1), were discovered. (laser applications and other topics in quantum electronics)

  7. Widefield laser doppler velocimeter: development and theory.

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-01

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

  8. Laser Doppler vibrometry: new ENT applications

    Science.gov (United States)

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

    1996-12-01

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

  9. A borescopic laser Doppler velocimetry probe

    Science.gov (United States)

    O'Brien, Kory T.; Ölçmen, Semih M.

    2014-07-01

    We present a miniature, fiber-optic, single-velocity-component laser Doppler velocimetry (LDV) probe for measurement in flows where access is very limited. The main probe neck is 7?mm in diameter. The probe operates in the backscatter mode. The borescopic design of the probe allows the neck of the probe to be as long as is needed to access remote locations. The neck length of the probe is 15.24?cm and was designed to make measurements at 30?mm away from the probe’s tip. The probe was tested in two free-jet flows, (i) pipe jet flow and (ii) convergent nozzle jet flow, to demonstrate the working principle of the probe.

  10. Transcranial doppler, EEG and SEP monitoring

    Directory of Open Access Journals (Sweden)

    A. Opp

    2009-07-01

    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.

  11. Coherent Detection in Laser Doppler Velocimeters

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner

    1974-01-01

    The possibility of heterodyning between electromagnetic waves scattered by particles separated in space is explained from a classical point of view and from a quantum mechanical point of view. The last description being carried out using only the Heisenberg uncertainty principle and a rather coarse, but intelligible particle picture of electromagnetic waves. The analysis is carried out with special emphasis on the heterodyning process in the laser Doppler velocimeter (LDV) because the main purpose of this article is to provide a better understanding of this instrument. An aid for this purpose is the evaluation of a visual comprehensive interference pattern (Moiré pattern), which furthermore reveals some important features of the optical set-up.

  12. Implementation of Doppler backscattering for MAST

    CERN Document Server

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

    2014-01-01

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

  13. Geodetic Satellite Doppler Positioning and Application to Canadian Test Adjustments

    Science.gov (United States)

    Kouba, J.

    1980-01-01

    During 1974-6, the Geodetic Survey of Canada established a geodetic control network with spacing between points of about 200-500 km with the use of the satellite-Doppler method. For this application, a unique observation strategy and Doppler data reduction procedures have been developed, by using both precise and broadcast satellite ephemerides. The satellite-Doppler geodetic control has contributed greatly to the readjustment of the Canadian triangulation network, in particular to the datum orientation and positioning. The results have also been useful for geoid studies in Canada. Continuous satellite-Doppler tracking from the two Canadian Tranet stations provides additional information on polar motion and long-term variations of the satellite system, which are important for monitoring and maintaining the related geodetic datum. The basic Doppler control at 200-500 km has been completed and successfully used in the test adjustment of the Canadian geodetic network. Currently, the Doppler method is used for densification at station spacing below 100 km, and in conjunction with the Inertial Survey Systems. A possible difference between Canadian and the U.S. astronomical observations has been encountered. Further research and field programmes are necessary to solve this problem. Permanent Doppler monitoring is viewed as essential for geodetic datum maintenance and determination of time-related aspects of future precise geodetic networks. The research in Canada is directed towards improvements and better understanding of the relation between the different methods of precise global positioning.

  14. Role of colour doppler sonography in adnexal masses

    Directory of Open Access Journals (Sweden)

    Shazia Ashraf Khan, Aamina Banoo

    2014-04-01

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

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

    Science.gov (United States)

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

    1986-10-01

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

  16. Sub-Doppler laser cooling of potassium atoms

    CERN Document Server

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

    2011-01-01

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

  17. Sub-Doppler laser cooling of potassium atoms

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-15

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

  18. Laser Doppler anemometer signal processing for blood flow velocity measurements

    Science.gov (United States)

    Borozdova, M. A.; Fedosov, I. V.; Tuchin, V. V.

    2015-03-01

    A new method for analysing the signal in a laser Doppler anemometer based on the differential scheme is proposed, which provides the flow velocity measurement in strongly scattering liquids, particularly, blood. A laser Doppler anemometer intended for measuring the absolute blood flow velocity in animal and human near-surface arterioles and venules is developed. The laser Doppler anemometer signal structure is experimentally studied for measuring the flow velocity in optically inhomogeneous media, such as blood and suspensions of scattering particles. The results of measuring the whole and diluted blood flow velocity in channels with a rectangular cross section are presented.

  19. Considerations pertinent to the Doppler effect for space reactors

    International Nuclear Information System (INIS)

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

  20. Rotational Doppler Effect and Barnett Field in Spinning NMR

    Science.gov (United States)

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

    2015-04-01

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

  1. Processor operated correlator with applications to laser Doppler signals

    OpenAIRE

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

    2009-01-01

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

  2. 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.

  3. Sub-Doppler laser cooling of potassium atoms

    OpenAIRE

    Landini, M.; Roy, S.; Carcagn Xec, L.; Trypogeorgos, D.; Fattori, M.; Inguscio, M.; Modugno, G.

    2011-01-01

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

  4. Doppler study of cerebral arteries in hypercholesterolemia

    Directory of Open Access Journals (Sweden)

    Farhoudi M

    2011-03-01

    Full Text Available 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 blood flow velocities in patients with hypercholesterolemia, the number of these studies has been limited. The aim of this study was to assess the hemodynamic status of the cerebral arteries in patients with hypercholesterolemia using TCD.Methods: In a case-control study, 60 individuals, including 30 hypercholesterolemic cases (low-density lipoprotein [LDL] > 160 mg/dL and 30 healthy controls were enrolled. Other arterial risk factors, including diabetes mellitus, hypertension, smoking, and obesity (body mass index > 30, were evaluated and matched as well. TCD was used to assess the hemodynamics of the intracranial arteries as well as the internal carotid arteries. The mean blood flow velocity, pulsatility index, and resistance index were recorded in all the arteries.Results: The mean blood flow velocity, pulsatility index, and resistance index of the intracranial arteries and internal carotid arteries were not significantly different between the two groups (P > 0.05. However, those with higher levels of LDL (>180 mg/dL showed significantly lower mean blood flow velocity and resistance index of the internal carotid arteries than the healthy controls. In addition, individuals with high-density lipoprotein (HDL <35 mg/dL had significantly lower mean blood flow velocity in the internal carotid arteries.Conclusion: Hypercholesterolemia (LDL > 160 mg/dL does not seem to have a detrimental effect on the hemodynamic status of the intracranial arteries and internal carotid arteries. However, in cases of higher LDL (>180 mg/dL and lower HDL, decreased TCD parameters in the internal carotid arteries, as a surrogate of the peripheral arteries, are prominent.Keywords: hypercholesterolemia, transcranial Doppler, cerebral arteries

  5. GRIP DOPPLER AEROSOL WIND LIDAR (DAWN) V1

    National Aeronautics and Space Administration — The Doppler Aerosol WiNd (DAWN), a pulsed lidar, operated aboard a NASA DC-8 aircraft during the Genesis and Rapid Intensification Processes (GRIP) field campaign....

  6. Doppler Compensation by using of Segmented Match Filter

    Directory of Open Access Journals (Sweden)

    Nader Ghadimi

    2008-09-01

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

  7. Applications of doppler effect in navigation and oceanography

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    2000-01-01

    of practical interest. For example, the Doppler effect contributed significantly to a greater understanding of the motion of celestial bodies, cosmic objects, stars, and quasars, primarily through measurement of the red shift or blue shift in their spectral...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-01

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

  9. Doppler Signatures of the Atmospheric Circulation on Hot Jupiters

    CERN Document Server

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

    2013-01-01

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

  10. Learning Based Falling Detection Using Multiple Doppler Sensors

    Directory of Open Access Journals (Sweden)

    Shoichiro Tomii

    2013-06-01

    Full Text Available Automated falling detection is one of the important tasks in this ageing society. Such systems are supposed to have little interference on daily life. Doppler sensors have come to the front as useful devices to detect human activity without using any wearable sensors. The conventional Doppler sensor based falling detection mechanism uses the features of only one sensor. This paper presents falling detection using multiple Doppler sensors. The resulting data from sensors are combined or selected to find out the falling event. The combination method, using three sensors, shows 95.5% accuracy of falling detection. Moreover, this method compensates the drawbacks of mono Doppler sensor which encounters problems when detecting movement orthogonal to irradiation directions.

  11. Ambiguity Of Doppler Centroid In Synthetic-Aperture Radar

    Science.gov (United States)

    Chang, Chi-Yung; Curlander, John C.

    1991-01-01

    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.

  12. CAMEX-4 MIPS 915 MHZ DOPPLER WIND PROFILER V1

    National Aeronautics and Space Administration — The University of Alabama in Huntsville (UAH) Mobile Integrated Profiling System (MIPS) is a mobile atmospheric profiling system. It includes a 915 MHz Doppler...

  13. Folded-path doppler and the measurement of blood flow

    Science.gov (United States)

    Crane, H. Richard

    1999-09-01

    Everyone who has listened to a train go by while blowing its whistle has heard the Doppler frequency shift. The practical problem is finding the velocity of something moving at some distance that neither transmits nor receives.

  14. 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.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

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

  16. Dove prism based rotating dual beam bidirectional Doppler OCT

    OpenAIRE

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

    2013-01-01

    Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The pr...

  17. 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.)

  18. DELAY-DOPPLER PERFORMANCE OF HYPERBOLIC FREQUENCY MODULATION WAVEFORMS

    OpenAIRE

    Nagajyothi, A.; Raja Rajeswari, K.

    2013-01-01

    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 frequenc...

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

    Science.gov (United States)

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

    2012-07-03

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

  20. Non-Gaussianity and CMB aberration and Doppler

    OpenAIRE

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

    2013-01-01

    The peculiar motion of an observer with respect to the CMB rest frame induces a deflection in the arrival direction of the observed photons (also known as CMB aberration) and a Doppler shift in the measured photon frequencies. As a consequence, aberration and Doppler effects induce non trivial correlations between the harmonic coefficients of the observed CMB temperature maps. In this paper we investigate whether these correlations generate a bias on Non-Gaussianity estimato...

  1. Prospects for Doppler cooling of three-electronic-level molecules

    OpenAIRE

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

    2010-01-01

    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...

  2. Role of colour doppler sonography in adnexal masses

    OpenAIRE

    Shazia Ashraf Khan, Aamina Banoo

    2014-01-01

    Objective: To evaluate the role of colour Doppler sonography in differentiating between benign and malignant adnexal masses. Materials & Methods: One hundred women diagnosed with adnexal masses underwent colour Doppler sonography. Resistance index (RI) and Pulsatility index (PI) were calculated in each case and lowest RI and PI obtained at any point in the mass were considered for analysis. Masses which were completely a vascular were considered as benign. Histopathological diagnosis was obta...

  3. Doppler ultrasonographic changes in the canine kidney during normovolaemic anaemia

    OpenAIRE

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

    2006-01-01

    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...

  4. Narrowing of EIT resonance in a Doppler Broadened Medium

    OpenAIRE

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

    2001-01-01

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

  5. Fiberoptic laser-Doppler anemometer for industrial flow measurement

    International Nuclear Information System (INIS)

    The paper describes laser-Doppler anemometers whose sending and receiving lenses are decoupled from the rest of the optics by means of glassfibers. This technique yields robust fiber optical probes, which work under industrial conditions. Their application to practical flows is shown and preliminary measurements are presented. The measurements indicate that fiber optical laser-Doppler systems are not only easy to handle, they can also yield LDA-signal quality comparable to conventional systems. (orig.)

  6. Blood flow measurement by laser Doppler method in orofacial region

    OpenAIRE

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

    2010-01-01

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

  7. Measurement of Water Flowing Velocity Using Laser Doppler Velocimetry Technique

    International Nuclear Information System (INIS)

    A Doppler laser differential method was used to measure the velocity of water flowing in a transparent glass tube in two cases : 1) a tap water and 2) a water pumped by a fish tank pump, the water had been colored with potassium permanganate (KMnO4). Several measurements of the water velocity were carried out manually and with Doppler laser differential method for both cases. The comparison between these measurements shows a reasonable agreement. (Authors)

  8. Large Doppler Compensation for Mobile OFDM Based Underwater Acoustic Communication

    OpenAIRE

    Zhengrong Pan; Chi Wang; Jingwei Yin

    2013-01-01

    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 ...

  9. A characteristic continuous wave Doppler signal in cor triatriatum?

    OpenAIRE

    Glaser, Joram

    1992-01-01

    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...

  10. Hydronephrosis and pregnancy: study with Doppler echography

    International Nuclear Information System (INIS)

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

  11. SIAMOIS: a Doppler asteroseismometer for Dome C

    Science.gov (United States)

    Mosser, B.; Maillard, J.-P.

    The photometric instruments in space (most, corot) are going to open new insights on the knowledge of stellar interiors. However, ground-based asteroseismic observations remain justified as they can bring complementary velocity measurements, and allow the study of much more targets. A competitive instrument must make it possible the observation of a representative set of solar-like stars with magnitude down to 5, and a velocity precision as low as a few cm s-1 after 5 nights behind a 2-m class telescope. The siamois project based on a Fourier interferometer has emerged as a suitable solution to fulfil the specifications for a ground-based asteroseismic network. The photon noise limited performances have been examined and compared to those of a grating spectrometer (Mosser et al. 2003) showing that this type of instrument can reach the required specifications. With a design based on a monolithic interferometer, with a compact instrument easy to set up, to operate remotely with a limited data-flow, it can fit well the harsh conditions of Dome C. Main advantage, a single unit is needed due to the circumpolar position of the targets for the Doppler detection of stellar oscillations on solar-type stars. As a test bed, siamois could be put on 0.8-m class telescope like irait (Busso et al. these proceedings).

  12. 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

  13. Evaluating microcirculation by pulsatile laser Doppler signal

    Energy Technology Data Exchange (ETDEWEB)

    Chao, P T [Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China); Department of Physics, National Taiwan Normal University, Taipei, Taiwan (China); Biophysics Lab, Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Jan, M Y [Biophysics Lab, Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Hsiu, H [Biophysics Lab, Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Department of Electrical Engineering, Yuan-ze University, Chun-Li, Taiwan (China); Hsu, T L [Biophysics Lab, Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Wang, W K [Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China); Biophysics Lab, Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Wang, Y Y Lin [Department of Physics, National Taiwan Normal University, Taipei, Taiwan (China); Biophysics Lab, Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China)

    2006-02-21

    Laser Doppler flowmetry (LDF) is a popular method for monitoring the microcirculation, but it does not provide absolute measurements. Instead, the mean flux response or energy distribution in the frequency domain is generally compared before and after stimulus. Using the heartbeat as a trigger, we investigated whether the relation between pressure and flux can be used to discriminate different microcirculatory conditions. We propose the following three pulsatile indices for evaluating the microcirculation condition from the normalized pressure and flux segment with a synchronized-averaging method: peak delay time (PDT), pressure rise time and flux rise time (FRT). The abdominal aortic blood pressure and renal cortex flux (RCF) signals were measured in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The mean value of the RCF did not differ between SHR and WKY. However, the PDT was longer in SHR (87.14 {+-} 5.54 ms, mean {+-} SD) than in WKY (76.92 {+-} 2.62 ms; p < 0.001). The FRT was also longer in SHR (66.56 {+-} 1.98 ms) than in WKY (58.02 {+-} 1.77 ms; p < 0.001). We propose that a new dimension for comparing the LDF signals, which the results from the present study show, can be used to discriminate RCF signals that cannot be discriminated using traditional methods.

  14. Evaluating microcirculation by pulsatile laser Doppler signal

    International Nuclear Information System (INIS)

    Laser Doppler flowmetry (LDF) is a popular method for monitoring the microcirculation, but it does not provide absolute measurements. Instead, the mean flux response or energy distribution in the frequency domain is generally compared before and after stimulus. Using the heartbeat as a trigger, we investigated whether the relation between pressure and flux can be used to discriminate different microcirculatory conditions. We propose the following three pulsatile indices for evaluating the microcirculation condition from the normalized pressure and flux segment with a synchronized-averaging method: peak delay time (PDT), pressure rise time and flux rise time (FRT). The abdominal aortic blood pressure and renal cortex flux (RCF) signals were measured in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The mean value of the RCF did not differ between SHR and WKY. However, the PDT was longer in SHR (87.14 ± 5.54 ms, mean ± SD) than in WKY (76.92 ± 2.62 ms; p < 0.001). The FRT was also longer in SHR (66.56 ± 1.98 ms) than in WKY (58.02 ± 1.77 ms; p < 0.001). We propose that a new dimension for comparing the LDF signals, which the results from the present study show, can be used to discriminate RCF signals that cannot be discriminated using traditional methods

  15. [Doppler echocardiography and double chamber pacing].

    Science.gov (United States)

    Mabo, P; Varin, C; De Place, C; Kermarrec, A; Berder, V; Daubert, C

    1992-05-01

    Doppler-echocardiography is playing an increasing role in cardiac pacing: 1) Before implantation, to determine any cardiac disease possibly accompanying the conduction disturbance, and the quality of atrial function in order to identify the appropriate indications for the type of pacing which will restore normal AV synchronism. Alongside morphometric data (size of atria, etc.), this analysis is based above all on the evaluation of LV filling flows and ejection, if necessary during provisional pacing in DRV mode. It is important to be aware of and prevent certain problems: 1st degree AV block with very long PR, high degree interatrial conduction disturbances, etc. 2) To evaluate the possible benefits of pacing in certain new indications, e.g. obstructive hypertrophic cardiomyopathy (measurement of intra-LV gradient in sinus rhythm and with DRV pacing with total ventricular capture). 3) After implantation, to optimise the programming of double-chamber pacemakers and in particular AV intervals (base-line AV interval with paced atrial cycle, AV interval with detected atrial cycle, hysteresis of AV interval corresponding to the difference between the two previous values, slope of automatic variation in AV interval during exercise, etc.). Individual programming of these parameters based upon analysis of transmitral and ejection flow rates, at rest and, if necessary, during exercise, enables the optimisation of cardiac function (which is above all useful in the presence of concomitant organic heart disease) while at the same time improving the electrophysiological behaviour of the pacemaker at high frequencies. PMID:1416772

  16. Single mode, extreme precision Doppler spectrographs

    CERN Document Server

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

    2012-01-01

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

  17. Analysis of Radar Doppler Signature from Human Data

    Directory of Open Access Journals (Sweden)

    M. ANDRI?

    2014-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Armstrong J. W.

    2006-01-01

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

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

    LENUS (Irish Health Repository)

    Kennelly, M M

    2012-04-01

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

  20. 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)

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

    Scientific Electronic Library Online (English)

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

    2014-02-01

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

  2. Hands-Free Transcranial Color Doppler Probe

    Science.gov (United States)

    Chin, Robert; Madala, Srihdar; Sattler, Graham

    2012-01-01

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

  3. 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.)

  4. Single Mode, Extreme Precision Doppler Spectrographs

    Science.gov (United States)

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

    2014-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Takahashi I

    2013-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Park, Nakgyu; Baik, Sunghoon; Park, Seungkyu; Kim, Donglyul [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Dukhyeon [Hanbat National Univ., Daejeon (Korea, Republic of)

    2014-05-15

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

  7. Estimation of pulmonary vascular resistance with Doppler diastolic gradients.

    Science.gov (United States)

    Atiq, Mehnaz; Tasneem, Habiba; Aziz, Kalimuddin

    2008-06-01

    This study was undertaken to determine the diastolic Doppler echocardiographic correlates of pulmonary vascular resistance calculated on cardiac catheterization in patients with secondary pulmonary arterial hypertension. Thirty-eight consecutive patients with congenital heart disease, pulmonary artery hypertension and pulmonary regurgitation were studied. Continuous-wave Doppler-derived pulmonary artery diastolic gradients were measured at 3 points on the pulmonary regurgitant diastolic velocity slope: peak diastolic, end-diastolic (at the R wave on the electrocardiogram), and mid-diastolic (midway between the peak and end-diastolic points). Catheterization data included oximetry, measurements of pressure in the cardiac chambers and great arteries, and calculation of pulmonary vascular resistance index. Doppler-derived peak, mid, and end-diastolic pulmonary regurgitation gradients correlated best with catheterization-measured pulmonary artery systolic, mean and diastolic pressures, respectively. The best Doppler correlate of pulmonary vascular resistance index was the pulmonary artery end-diastolic gradient. Clinically useful information can be obtained from Doppler pulmonary artery diastolic gradients measured on the pulmonary regurgitant diastolic velocity slope, which can estimate the pulmonary arterial pressure as well as pulmonary vascular resistance obtained on cardiac catheterization. PMID:18515672

  8. Blood flow measurement by laser Doppler method in orofacial region

    Directory of Open Access Journals (Sweden)

    Grga ?urica

    2010-01-01

    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.

  9. 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

  10. Doppler Uterine Artery Flow Velocimetry in Prediction of Preterm Labor

    Directory of Open Access Journals (Sweden)

    Mahyar Mohammadi Fard

    2009-01-01

    Full Text Available "nIntroduction: To evaluate the role of Doppler waveforms of the uterine vessels in predicting preterm labor. "nMaterials and Methods: This was a retrospective analysis of the uterine artery Doppler findings of 28 15-25 week singleton pregnancies with a spontaneous preterm labor were compared to 326 pregnancies delivered at term. 354 women who presented to our medical center from April 20, 2008 to November 20, 2008 were enrolled in the study. Pulsed-wave Doppler measurements were made of the maternal uterine arteries. These women were followed up until delivery. "nResults: The uterine artery mean resistance index (RI was 0.76 and 0.66 in the preterm and term delivery groups, respectively (P < 0.05. Bilateral diastolic notches were present in 41% of the preterm deliveries and 27% of the controls (P < 0.05. The mean pulsatility index (PI was 1.40 and 1.83 (46% in the term and preterm delivery groups, respectively (P < 0.05. "nConclusion: Doppler of the uterine vessels could prove to be a good predictor of preterm labor. "nKey words: premature labor, prenatal diagnosis, uterus blood supply, pregnancy, ultrasound, color Doppler.  

  11. A study of doppler waveform using pulsatile flow model

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-08-01

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

  12. A study of doppler waveform using pulsatile flow model

    International Nuclear Information System (INIS)

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

  13. Quantitative Doppler ultrasound-based determination of volumetric blood flow

    Science.gov (United States)

    Ha, Jun S.; Hossack, John A.

    2002-04-01

    Conventional ultrasound Doppler velocity measurements are scaled by the cosine of the angle between the blood flow axis and ultrasound beam axis. In the approach used here, a transducer array was used to acquire a first cross-sectional Doppler data set of the vessel under examination. The transducer array was then moved to a different angle to acquire a second cross-sectional Doppler data set. Thereafter, we used the known angle between the two arrays ultrasound beams and the cosine (theta) scaled Doppler estimates to solve for the true angle between the blood flow axis and ultrasound beam axis of the first data set. Upon integrating the angle corrected velocity estimates over the entire vessel cross-section, we were able to estimate blood volume flow rate. The performance of the new approach was tested in a flow phantom that was designed to provide a constant flow in a simulated vessel. The data were collected for two sets of angles and three different flow velocities for each angle set. The unknown Doppler angle was calculated from the data and used to correct the flow velocity.

  14. 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

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

    Directory of Open Access Journals (Sweden)

    Ali Pahlusi

    2011-10-01

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

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

    Scientific Electronic Library Online (English)

    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

    Full Text Available 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

  17. Signal processing considerations for low signal to noise ratio laser Doppler and phase Doppler signals

    Science.gov (United States)

    Ibrahim, K. M.; Wertheimer, G. D.; Bachalo, William D.

    1991-01-01

    The relative performance of current methods used for estimating the phase and the frequency in LDV and phase Doppler applications in low signal to noise ratio conditions is analyzed. These methods include the Fourier analysis and the correlation techniques. Three methods that use the correlation function for frequency and phase estimations are evaluated in terms of accuracy and speed of processing. These methods include: (1) the frequency estimation using zero crossings counting of the auto-correlation function, (2) the Blackman-Tukey method, and (3) the AutoRegressive method (AR). The relative performance of these methods is evaluated and compared with the Fourier analysis method which provides the optimum performance in terms of the Maximum Likelihood (ML) criteria.

  18. Three-dimensional laser cooling at the Doppler limit

    CERN Document Server

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

    2014-01-01

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

  19. Three-dimensional laser cooling at the Doppler limit

    Science.gov (United States)

    Chang, R.; Hoendervanger, A. L.; Bouton, Q.; Fang, Y.; Klafka, T.; Audo, K.; Aspect, A.; Westbrook, C. I.; Clément, D.

    2014-12-01

    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 ? ? /2 kB , where ? 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 sensitivity of optical molasses to a power imbalance in the laser beams, finding excellent agreement with 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. This discussion can be generalized to identify when a given species is likely to be subject to the same limitation.

  20. Non-intrusive Shock Measurements Using Laser Doppler Vibrometers

    Science.gov (United States)

    Statham, Shannon M.; Kolaini, Ali R.

    2012-01-01

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

  1. Implementation of a novel pulsed ultrasonic Doppler velocity profiler

    Science.gov (United States)

    Luo, Shounan; Liu, Yan; Feng, Guanping

    2003-09-01

    The objective of the work is to apply advanced digital signal processing (DSP) and pulsed Doppler echography techniques to analyze velocity profile of the measured fluid in a closed full-pipe. In order to reliably measure velocity profile where non-intrusive ultrasonic Doppler velocity profilers (UDVPs) cannot properly transmit and receive ultrasonic signals, a single-crystal transducer was inserted directly into the fluid stream. Then ultrasonic signals were transmitted and received based on the pulsed Doppler echography theory. A modified covariance (MCOV) estimator and a TMS320VC5410 DSP chip with a high-speed up to 160 MIPS were employed to analyze spectrum of the software-gated echo signals. Finally, computer simulations were also presented to demonstrate effectiveness of the novel UDVP. Results indicate that this instrument is particularly effective in terms of velocity profiling and can be widely applied for flow measurement and fluid dynamics research.

  2. Spaceborne Doppler Precipitation Radar: System Configurations and Performance Analysis

    Science.gov (United States)

    Tanelli, Simone; Im, Eastwood

    2004-01-01

    Knowledge of the global distribution of the vertical velocity of precipitation is important in in the study of energy transportation in the atmosphere, the climate and weather. Such knowledge can only be directly acquired with the use of spaceborne Doppler precipitation radars. Although the high relative speed of the radar with respect to the rainfall particles introduces significant broadening in the Doppler spectrum, recent studies have shown that the average vertical velocity can be measured to acceptable accuracy levels by appropriate selection of radar parameters. Furthermore, methods to correct for specific errors arising from NUBF effects and pointing uncertainties have recently been developed. In this paper we will present the results of the trade studies on the performances of a spaceborne Doppler radar with different system parameters configurations.

  3. Non-Gaussianity and CMB aberration and Doppler

    CERN Document Server

    Catena, Riccardo; Notari, Alessio; Renzi, Alessandro

    2013-01-01

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

  4. Holographic laser Doppler imaging of microvascular blood flow

    CERN Document Server

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

    2014-01-01

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

  5. Visualisation of 4-D colour and power Doppler data.

    Science.gov (United States)

    Jones, Mike G; Shipley, Jacqueline A; Robinson, Teresa M

    2003-12-01

    Mechanically scanned, cardiac-gated, 4-D colour Doppler and power Doppler data were acquired and rendered using multiplanar slice display, surface-fitting (S-F) and direct volume rendering (DVR), with interactive viewpoint control or tool command language (Tcl)-scripted generation of animation sequences across the cardiac cycle. S-F applied the marching cubes algorithm within a YCbCr colour space to extract time-varying Doppler regions; supplementally generated surfaces enclosed all regions across the full cardiac cycle, partially to alleviate the problem of incomplete vessel filling. DVR used integrated intensity, maximum intensity and front-to-back projection; the latter applied an opacity function to the Cb, Cr and Y colour channels to control the appearance of the blood flow signal relative to the background B-mode image. Our most detailed display was a hybrid approach that combined multiplanar slicing and DVR. PMID:14698341

  6. Assessment of endometrial receptivity by Color Doppler and ultrasound imaging

    Directory of Open Access Journals (Sweden)

    Lili? Vekoslav

    2007-01-01

    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.

  7. Precision Measuring of Velocities via the Relativistic Doppler Effect

    CERN Document Server

    Ozernoy, L M

    1997-01-01

    Just as the ordinary Doppler effect serves as a tool to measure radial velocities of celestial objects, so can the relativistic Doppler effect be implemented to measure a combination of radial and transverse velocities by using recent improvements in observing techniques. A key element that makes a further use of this combination feasible is the periodicity in changes of the orbital velocity direction for the source. Two cases are considered: (i) a binary star; and (ii) a solitary star with the planetary companion. It is shown that, in case (i), several precision Doppler measurements employing the gas absorption cell technique would determine both the total orbital velocity and the inclination angle of the binary orbit disentangled from the peculiar velocity of the system. The necessary condition for that is the measured, at least with a modest precision, proper motion and distance to the system.

  8. Effective particle size range in laser-Doppler anemometry

    International Nuclear Information System (INIS)

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

  9. 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)

  10. 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)

  11. Effect of surface reflectivity on photonic Doppler velocimetry measurement

    Science.gov (United States)

    Wu, Xianqian; Xia, Weiguang; Wang, Xi; Song, Hongwei; Huang, Chenguang

    2014-05-01

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

  12. Synthetic Doppler maps of gaseous flows in IP Peg

    CERN Document Server

    Kuznetsov, O A; Boyarchuk, A A; Khruzina, T S; Cherepashchuk, A M

    2001-01-01

    We present synthetic Doppler maps of gaseous flows in binary IP Peg based on the results of 3D gasdynamical simulations. Using of gasdynamical calculations alongside with the Doppler tomography technique permits us to identify the main features of the flow on the Doppler maps without solution of an ill-posed inverse problem. Comparison of synthetic tomograms with observations shows that in quiescence there are two zones of high emission: a shock wave on the edge of the stream from L_1 caused by the interaction of the gas of circumbinary envelope and the stream, and the dense region in a apoastron of quasi-elliptical accretion disk. A single arm of the spiral shock and the stream itself give a minor input to the total brightness. During outburst the accretion disk dominates, and the most emitive regions are the two arms of the spiral shock.

  13. Delay and Doppler spreads in underwater acoustic particle velocity channels.

    Science.gov (United States)

    Guo, Huaihai; Abdi, Ali; Song, Aijun; Badiey, Mohsen

    2011-04-01

    Signal processing and communication in acoustic particle velocity channels using vector sensors are of interest in the underwater medium. Due to the presence of multiple propagation paths, a mobile receiver collects the signal with different delays and Doppler shifts. This introduces certain delay and Doppler spreads in particle velocity channels. In this paper, these channel spreads are characterized using the zero-crossing rates of channel responses in frequency and time domain. Useful expressions for delay and Doppler spreads are derived in terms of the key channel parameters mean angle of arrival and angle spread. These results are needed for design and performance prediction of systems that utilize underwater acoustic particle velocity and pressure channels. PMID:21476657

  14. 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

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

    Science.gov (United States)

    Browne, Jacinta E

    2014-11-01

    In this paper, an overview of Doppler ultrasound quality assurance (QA) testing will be presented in three sections. The first section will review the different Doppler ultrasound parameters recommended by professional bodies for use in QA protocols. The second section will include an evaluation and critique of the main test devices used to assess Doppler performance, while the final section of this paper will discuss which of the wide range of test devices have been found to be most suitable for inclusion in Doppler QA programmes. Pulsed Wave Spectral Doppler, Colour Doppler Imaging QA test protocols have been recommended over the years by various professional bodies, including the UK's Institute of Physics and Engineering in Medicine (IPEM), the American Institute for Ultrasound in Medicine (AIUM), and the International Electrotechnical Commission (IEC). However, despite the existence of such recommended test protocols, very few commercial or research test devices exist which can measure the full range of both PW Doppler ultrasound and colour Doppler imaging performance parameters, particularly quality control measurements such as: (i) Doppler sensitivity (ii) colour Doppler spatial resolution (iii) colour Doppler temporal resolution (iv) colour Doppler velocity resolution (v) clutter filter performance and (vi) tissue movement artefact suppression. In this review, the merits of the various commercial and research test devices will be considered and a summary of results obtained from published studies which have made use of some of these Doppler test devices, such as the flow, string, rotating and belt phantom, will be presented. PMID:25212384

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

    International Nuclear Information System (INIS)

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

  17. Numerical stud of glare spot phase Doppler anemometry

    OpenAIRE

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

    2008-01-01

    The phase Doppler anemometry has (PDA) been developed to measure simultaneously the velocity and the size of droplets. When the concentration of particles is high, tightly focused beams must be used, as in the dual burst PDA. The latter permits an access to the refractive index of the particle, but the effect of wave front curvature of the incident beams becomes evident. In this paper, we introduce a glare spot phase Doppler anemometry which uses two large beams. The images of the particle fo...

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

    International Nuclear Information System (INIS)

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

  19. Void effects on BWR Doppler and void reactivity feedback

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup

    2008-01-01

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

  1. Tracking airborne targets occasionally hidden in the blind Doppler

    Science.gov (United States)

    Gordon, Neil J.; Ristic, Branko

    2001-11-01

    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.

  2. Application of Hilbert-Huang transform to laser Doppler velocimeter

    Science.gov (United States)

    Xiaoming, Nie; Jian, Zhou; Xingwu, Long

    2012-10-01

    A new method based on Hilbert-Huang transform is proposed to analyze the laser Doppler signal with a large acceleration. The Doppler signal is decomposed into several Intrinsic Mode Functions (IMFs) via empirical mode decomposition (EMD). And the Hilbert transform is used to compute the instantaneous frequency. The vehicle velocity parameter is estimated by taking linear fitting on the instantaneous frequency of the relevant IMF. The simulation results show that the HHT-based method is quite useful for the LDV that offers velocity parameter to the vehicle self-contained navigation system when the vehicle moves at a large acceleration.

  3. ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO

    Directory of Open Access Journals (Sweden)

    Marcelo Rodríguez G

    2010-01-01

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

  4. ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO

    Scientific Electronic Library Online (English)

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

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

  5. Doppler-free spectroscopy in driven three-level systems

    OpenAIRE

    Rapol, Umakant D.; Natarajan, Vasant

    2005-01-01

    We demonstrate two techniques for studying the features of three-level systems driven by two lasers (called control and probe), when the transitions are Doppler broadened as in room-temperature vapor. For $\\Lambda$-type systems, the probe laser is split to produce a counter-propagating pump beam that saturates the transition for the zero-velocity atoms. Probe transmission then shows Doppler-free peaks, which can even have sub-natural linewidth. For V-type systems, the transm...

  6. Miniature Laser Doppler Velocimeter for Measuring Wall Shear

    Science.gov (United States)

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

    2005-01-01

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

  7. Doppler controlled dynamics of a mirror attached to a spring

    OpenAIRE

    Karrai, Khaled; Favero, Ivan; Metzger, Constanze

    2007-01-01

    A laser beam directed at a mirror attached onto a flexible mount extracts thermal energy from its mechanical Brownian motion by Doppler effect. For a normal mirror the efficiency of this Doppler cooling is very weak and masked by laser shot-noise. We find that it can become very efficient using a Bragg mirror at the long wavelength edge of its band stop. The opposite effect of cooling opens new routes for optical pumping of mechanical systems: a laser pointing at a Bragg mir...

  8. Calculation results and experimental testing of doppler feedback coefficients

    International Nuclear Information System (INIS)

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

  9. Development of two-frequency planar doppler velocimetry instrumentation

    OpenAIRE

    Charrett, Thomas O. H.

    2006-01-01

    This thesis describes the development of the two-frequency Planar Doppler Velocimetry (2n-PDV) flow measurement technique. This is modification of the Planar Doppler Velocimetry (PDV) technique that allows the measurement of up to three components of the flow velocity across a plane defined by a laser light sheet. The 2n-PDV technique reduces the number of components required to a single CCD camera and iodine cell from the two CCDs in conventional PDV. This removes the error so...

  10. [Doppler technologies in combined diagnosis of acute pyelonephritis].

    Science.gov (United States)

    Maksimov, V A; Prokhorov, A V; Kazachenko, A V; Ignashin, N S; Borisisk, V I; Karpov, V K; Amelin, A V; Andronov, A S

    2005-01-01

    We studied diagnostic potentialities of conventional clinical, device, x-ray and ultrasonic methods including current Doppler technology in differentiation of serous and purulent stages of acute pyelonephritis (AP) in 50 patients (mean age 25.5 +/- 5.5 years). Energetic dopplerangiography (EDA) showed the highest diagnostic significance. EDA was highly informative in renal carbuncle and total purulent destruction of the kidney and low informative in serous and apostematous AP, renal abscess. Conventional ultrasonic, x-ray, clinical and device investigations as well as impulse dopplerography and color Doppler mapping of blood flow are of secondary importance in AP. PMID:16419479

  11. Special theory of relativity through the Doppler effect

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  12. Large Doppler Compensation for Mobile OFDM Based Underwater Acoustic Communication

    Directory of Open Access Journals (Sweden)

    Zhengrong Pan

    2013-01-01

    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.

  13. Stretched-exponential Doppler spectra in underwater acoustic communication channels.

    Science.gov (United States)

    van Walree, P A; Jenserud, T; Otnes, R

    2010-11-01

    The theory of underwater sound interacting with the sea surface predicts a Gaussian-spread frequency spectrum in the case of a large Rayleigh parameter. However, recent channel soundings reveal more sharply peaked spectra with heavier tails. The measured Doppler spread increases with the frequency and differs between multipath arrivals. The overall Doppler spectrum of a broadband waveform is the sum of the spectra of all constituent paths and frequencies, and is phenomenologically described by a stretched or compressed exponential. The stretched exponential also fits well to the broadband spectrum of a single propagation path, and narrowband spectra summed over all paths. PMID:21110547

  14. 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

  15. Fano-Doppler laser cooling of hybrid nanostructures.

    Science.gov (United States)

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

    2011-09-27

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

  16. NITROSAMINAS VOLÁTEIS EM ALIMENTOS

    Directory of Open Access Journals (Sweden)

    C. B. DUTRA

    2008-11-01

    Full Text Available

    Nitrosaminas são compostos potencialmente carcinogênicos para o homem, as quais podem ocorrer em alimentos como produto da reação entre aminas secundárias e agentes nitrosantes. Neste artigo de revisão são fornecidas informações sobre os aspectos toxicológicos, epidemiológicos, presença em alimentos e legislação sobre estes compostos.

  17. 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

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

    LENUS (Irish Health Repository)

    Unterscheider, Julia

    2013-12-01

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

  19. Doppler measurement integration for kinematic real-time GPS positioning

    OpenAIRE

    Agostino, Mattia; Manzino, Ambrogio

    2010-01-01

    The present paper discusses the advantages of the use of Doppler shift measurements in a Kalman filter estimator in order to improve the kinematic stand-alone global positioning system positioning performance. Tests conducted in an urban environment using a single-frequency receiver demonstrate the real advantages of the proposed real- time computation technique

  20. A simplified study of trans-mitral Doppler patterns

    Directory of Open Access Journals (Sweden)

    Thomas George

    2008-11-01

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

  1. Flow profile study using miniature laser-Doppler velocimetry

    Science.gov (United States)

    Booij, W. E.; de Jongh, A.; de Mul, F. F. M.

    1995-11-01

    We present a physics experiment, in which laser-Doppler velocimetry is used to make first-year university physics students realize that the idealized solutions offered by standard text books seldom are applicable without corrections, which often are numerical. This is demonstrated by carefully measuring and calculating the flow profile in a rectangular pipe.

  2. Enhanced color Doppler sonography of eye and orbit tumors

    International Nuclear Information System (INIS)

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

  3. Diastolic Dysfunction: Pathogenesis, Therapy and the Importance of Doppler Echocardiography

    OpenAIRE

    Yalc?in, Fatih

    1999-01-01

    Diastolic dysfunction is characterized by increased resistance to ventricular filling, inappropriate upward shift of the diastolic pressure-volume relationship and exercise intolerance. Inappropriate tachycardia, decreased diastolic compliance and impaired systolic relaxation lead to diastolic dysfunction. Optimal therapy will depend on the type and pathophysiologic phase of disease. Doppler echocardiography is a valuable tool to diagnose diastolic dysfunction and therapeutic effects of dru...

  4. Usefulness of Doppler Parameter in Patients with Renal Transplantation

    International Nuclear Information System (INIS)

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

  5. Usefulness of Doppler Parameter in Patients with Renal Transplantation

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-15

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

  6. Complex Doppler effect in left-handed metamaterials

    Science.gov (United States)

    Ziemkiewicz, D.; Zieli?ska-Raczy?ska, S.

    2015-03-01

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

  7. Dual beam translator for use in Laser Doppler anemometry

    Science.gov (United States)

    Brudnoy, David M. (Albany, NY)

    1987-01-01

    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.

  8. In vivo combined photoacoustic and Doppler ultrasound imaging

    Science.gov (United States)

    Jiang, Yan; Harrison, Tyler; Forbrich, Alexander; Zemp, Roger J.

    2012-02-01

    The long-term goal of our research is to develop photoacoustic and Doppler ultrasound imaging methods for noninvasive estimation of the oxygen consumption rate (MRO2) in vivo. Previously, we have demonstrated a combined photoacoustic and high-frequency Doppler ultrasound system and shown the feasibility of flow velocity and oxygen saturation (sO2) estimation using double-ink flow phantoms. In this work, the results of in vitro sheep blood experiments are presented. Blood oxygen flux has been estimated at different sO2 levels and mean flow speeds, and the uncertainty of the measurement has been quantified. In vivo experiments have been performed on Swiss Webster mice to provide coregistered photoacoustic and Doppler flow images with imaging depths of ~2mm. Doppler bandwidth broadening technique has been used to obtain transverse flow velocity. The diameter of the blood vessel is ~500?m and the mean flow speed is 15cm/s. We are working towards sO2 estimation in vivo and 3D oxygen consumption imaging of tumors at depths beyond OR-PAM.

  9. Efficient implementations of ultrasound color Doppler algorithms on VLIW architectures

    Science.gov (United States)

    Dasgupta, Udayan; Magee, David P.; Ali, Murtaza

    2009-02-01

    DSP chips are gaining importance in ultrasound applications as the need for portability and low power grows. One of the more computationally demanding applications for ultrasound involves estimating blood flow characteristics using Doppler techniques. This ultrasound mode, called color Doppler ultrasound, is used to diagnose many conditions like blood clots, valve defects and blocked arteries. This work looks at mapping some typical color Doppler algorithms onto Texas Instruments' (TI's) high performance C64x+(TM) core. The algorithms include RF demodulation, wall filtering and flow power, velocity and turbulence estimation. This paper starts with a general technique for analyzing algorithm complexity in terms of CPU instruction cycles on VLIW architectures like the C64x+(TM). It then applies this technique to Doppler processing algorithms, explains their mapping to the C64x+(TM) architecture and derives lower bounds for the computational complexity for these algorithm kernels. For each of these algorithms, these estimates are finally compared to actual implementations, and various implementation tradeoffs will be illustrated. Based on these implementations, it will be shown that these algorithms can run on TI's C64x+(TM) based DSPs using a fraction of the available processing power.

  10. Combined photoacoustic and high-frequency power Doppler ultrasound imaging

    Science.gov (United States)

    Jiang, Yan; Harrison, Tyler; Ranasinghesagara, Janaka; Zemp, Roger J.

    2010-02-01

    Photoacoustic imaging has emerged as a promising technique for visualizing optically absorbing structures with ultrasonic spatial resolution. Since it relies on optical absorption of tissues, photoacoustic imaging is particularly sensitive to vascular structures even at the micro-scale. Power Doppler ultrasound can be used to detect moving blood irrespective of Doppler angles. However, the sensitivity may be inadequate to detect very small vessels with slow flow velocities. In this work, we merge these two synergistic modalities and compare power Doppler ultrasound images with high-contrast photoacoustic images. We would like to understand the advantages and disadvantages of each technique for assessing microvascular density, an important indicator of disease status. A combined photoacoustic and highfrequency ultrasound system has been developed. The system uses a swept-scan 25 MHz ultrasound transducer with confocal dark-field laser illumination optics. A pulse-sequencer enables ultrasonic and laser pulses to be interlaced so that photoacoustic and Doppler ultrasound images are co-registered. Experiments have been performed on flow phantoms to test the capability of our system and signal processing methods. Work in progress includes in vivo color flow mapping. This combined system will be used to perform blood oxygen saturation and flow estimations, which will provide us with the parameters to estimate the local rate of metabolic oxygen consumption, an important indicator for many diseases.

  11. Method and system of doppler correction for mobile communications systems

    Science.gov (United States)

    Georghiades, Costas N. (Inventor); Spasojevic, Predrag (Inventor)

    1999-01-01

    Doppler correction system and method comprising receiving a Doppler effected signal comprising a preamble signal (32). A delayed preamble signal (48) may be generated based on the preamble signal (32). The preamble signal (32) may be multiplied by the delayed preamble signal (48) to generate an in-phase preamble signal (60). The in-phase preamble signal (60) may be filtered to generate a substantially constant in-phase preamble signal (62). A plurality of samples of the substantially constant in-phase preamble signal (62) may be accumulated. A phase-shifted signal (76) may also be generated based on the preamble signal (32). The phase-shifted signal (76) may be multiplied by the delayed preamble signal (48) to generate an out-of-phase preamble signal (80). The out-of-phase preamble signal (80) may be filtered to generate a substantially constant out-of-phase preamble signal (82). A plurality of samples of the substantially constant out-of-phase signal (82) may be accumulated. A sum of the in-phase preamble samples and a sum of the out-of-phase preamble samples may be normalized relative to each other to generate an in-phase Doppler estimator (92) and an out-of-phase Doppler estimator (94).

  12. Doppler sonography in diagnosis of the acute scrotum

    Directory of Open Access Journals (Sweden)

    Nikoli? Olivera

    2006-01-01

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

  13. Color Doppler in the Assessment of Uteroplacental Circulation Insufficiency

    Directory of Open Access Journals (Sweden)

    Ahmad Soltani Shirazi

    2010-05-01

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

  14. Complex Doppler effect in left-handed metamaterials

    CERN Document Server

    Ziemkiewicz, David

    2014-01-01

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

  15. 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

  16. Methodology and reproducibility of bidirectional laser Doppler velocimetry

    International Nuclear Information System (INIS)

    Bidirectional laser Doppler velocimetry in conjunction with monochromatic fundus photography allows non invasive measurement of retinal blood velocity. We have shown that it gives reproducible results in humans and experimental animals which agree well with those of the radioactively labelled microsphere technique. (author)

  17. Airborne Wind Profiling Algorithm for Doppler Wind LIDAR

    Science.gov (United States)

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

    2015-01-01

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

  18. Role of Doppler Velocimetry in growth restricted fetuses

    Directory of Open Access Journals (Sweden)

    Dr. Khushali Gandhi

    2015-01-01

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

  19. Color Doppler Ultrasonography in Evaluation of the Postoperative Penis

    Directory of Open Access Journals (Sweden)

    M. Ghafouri

    2005-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-01-01

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

  1. Non-Gaussianity and CMB aberration and Doppler

    International Nuclear Information System (INIS)

    The peculiar motion of an observer with respect to the CMB rest frame induces a deflection in the arrival direction of the observed photons (also known as CMB aberration) and a Doppler shift in the measured photon frequencies. As a consequence, aberration and Doppler effects induce non trivial correlations between the harmonic coefficients of the observed CMB temperature maps. In this paper we investigate whether these correlations generate a bias on non-Gaussianity estimators fNL. We perform this analysis simulating a large number of temperature maps with Planck-like resolution (lmax = 2000) as different realizations of the same cosmological fiducial model (WMAP7yr). We then add to these maps aberration and Doppler effects employing a modified version of the HEALPix code. We finally evaluate a generalization of the Komatsu, Spergel and Wandelt non-Gaussianity estimator for all the simulated maps, both when peculiar velocity effects have been considered and when these phenomena have been neglected. Using the value v/c = 1.23 × 10?3 for our peculiar velocity, we found that the aberration/Doppler induced non-Gaussian signal is at most of about half of the cosmic variance ? for fNL both in a full-sky and in a cut-sky experimental configuration, for local, equilateral and orthogonal estimators. We conclude therefore that when estimating fNL it is safe to ignore aberration and Doppler effects if the primordial map is already Gaussian. More work is necessary however to assess whether a map which contains non-Gaussianity can be significantly distorted by a peculiar velocity

  2. Non-Gaussianity and CMB aberration and Doppler

    Energy Technology Data Exchange (ETDEWEB)

    Catena, Riccardo [Institut für Theoretische Physik, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Liguori, Michele; Renzi, Alessandro [INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Notari, Alessio, E-mail: riccardo.catena@theorie.physik.uni-goettingen.de, E-mail: michele.liguori@pd.infn.it, E-mail: notari@ffn.ub.es, E-mail: arenzi@pd.infn.it [Departament de Física Fondamental i Institut de Ciéncies del Cosmos, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona (Spain)

    2013-09-01

    The peculiar motion of an observer with respect to the CMB rest frame induces a deflection in the arrival direction of the observed photons (also known as CMB aberration) and a Doppler shift in the measured photon frequencies. As a consequence, aberration and Doppler effects induce non trivial correlations between the harmonic coefficients of the observed CMB temperature maps. In this paper we investigate whether these correlations generate a bias on non-Gaussianity estimators f{sub NL}. We perform this analysis simulating a large number of temperature maps with Planck-like resolution (lmax = 2000) as different realizations of the same cosmological fiducial model (WMAP7yr). We then add to these maps aberration and Doppler effects employing a modified version of the HEALPix code. We finally evaluate a generalization of the Komatsu, Spergel and Wandelt non-Gaussianity estimator for all the simulated maps, both when peculiar velocity effects have been considered and when these phenomena have been neglected. Using the value v/c = 1.23 × 10{sup ?3} for our peculiar velocity, we found that the aberration/Doppler induced non-Gaussian signal is at most of about half of the cosmic variance ? for f{sub NL} both in a full-sky and in a cut-sky experimental configuration, for local, equilateral and orthogonal estimators. We conclude therefore that when estimating f{sub NL} it is safe to ignore aberration and Doppler effects if the primordial map is already Gaussian. More work is necessary however to assess whether a map which contains non-Gaussianity can be significantly distorted by a peculiar velocity.

  3. Non-Gaussianity and CMB aberration and Doppler

    Science.gov (United States)

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

    2013-09-01

    The peculiar motion of an observer with respect to the CMB rest frame induces a deflection in the arrival direction of the observed photons (also known as CMB aberration) and a Doppler shift in the measured photon frequencies. As a consequence, aberration and Doppler effects induce non trivial correlations between the harmonic coefficients of the observed CMB temperature maps. In this paper we investigate whether these correlations generate a bias on non-Gaussianity estimators fNL. We perform this analysis simulating a large number of temperature maps with Planck-like resolution (lmax = 2000) as different realizations of the same cosmological fiducial model (WMAP7yr). We then add to these maps aberration and Doppler effects employing a modified version of the HEALPix code. We finally evaluate a generalization of the Komatsu, Spergel and Wandelt non-Gaussianity estimator for all the simulated maps, both when peculiar velocity effects have been considered and when these phenomena have been neglected. Using the value v/c = 1.23 × 10-3 for our peculiar velocity, we found that the aberration/Doppler induced non-Gaussian signal is at most of about half of the cosmic variance ? for fNL both in a full-sky and in a cut-sky experimental configuration, for local, equilateral and orthogonal estimators. We conclude therefore that when estimating fNL it is safe to ignore aberration and Doppler effects if the primordial map is already Gaussian. More work is necessary however to assess whether a map which contains non-Gaussianity can be significantly distorted by a peculiar velocity.

  4. Doppler tisular y estratificación del riesgo en la miocardiopatía hipertrófica / Tissue Doppler and Risk Stratification in Hypertrophic Cardiomyopathy

    Scientific Electronic Library Online (English)

    Juan P., Ochoa; Adrián, Fernández; Juan M., Filipuzzi; Agostina M., Fava; José H., Casabé; Fabián, Salmo; Fabián, Vaisbuj; Horacio J., Di Nunzio; Guillermo, Ganum; Eduardo, Guevara.

    2014-04-01

    Full Text Available Introducción El Doppler pulsado tisular ha demostrado beneficio en la detección temprana de la miocardiopatía hipertrófica y en el diagnóstico diferencial de esta con otras causas secundarias de hipertrofia. Objetivo Determinar el valor pronóstico de las velocidades miocárdicas sistólicas tisulares [...] preservadas en pacientes con diagnóstico de miocardiopatía hipertrófica. Material y métodos Se incluyeron 146 pacientes con diagnóstico de miocardiopatía hipertrófica, los cuales fueron evaluados en forma prospectiva mediante un estudio de ecocardiograma Doppler. Se obtuvieron las velocidades sistólicas tisulares del promedio de las velocidades septales y laterales; se compararon los pacientes con velocidades miocárdicas sistólicas tisulares preservadas (Sa = 8 cm/seg; cuartil superior) con los que presentaban velocidades disminuidas. Se definió como punto final primario a la presencia de muerte súbita, accidente cerebrovascular, insuficiencia cardíaca o internación de causa cardiovascular en el seguimiento. Resultados El 29% (n = 43) presentó velocidades miocárdicas sistólicas tisulares preservadas en las imágenes del Doppler tisular, con más frecuencia de varones (76,7% vs. 53,4%; p = 0,009) y sin diferencias en la edad. Los diámetros ventriculares y los espesores fueron similares, en tanto que el área auricular fue significativamente menor (23,7 ± 6,7 cm² vs. 28,8 ± 8 cm²; p Abstract in english Usefulness of Tissue Doppler Imaging to Identify Low Risk Patients with Diagnosis of Hypertrophic Cardiomyopathy Background Pulsed tissue Doppler imaging is a useful tool for the early detection of hypertrophic cardiomyopathy and the differential diagnosis of this disease from other secondary causes [...] of hypertrophy. Objective The aim of the study was to determine the prognostic significance of preserved systolic tissue velocities in patients with diagnosis of hypertrophic cardiomyopathy. Methods One hundred and forty six patients with diagnosis of hypertrophic cardiomyopathy were prospectively included by means of a Doppler echocardiography study. Systolic tissue velocities were obtained from the averaged septal and lateral velocities. Patients with preserved systolic tissue velocities (Sa = 8 cm/s; upper quartile) were compared with those presenting decreased velocities. The primary endpoint was defined as the presence of sudden death, stroke, heart failure, or hospitalization for cardiovascular causes at follow up. Results Twenty nine percent of patients (n = 43) presented preserved systolic tissue velocities in the tissue Doppler images, mostly in men (76.7% vs. 53.4%, p = 0.009) and with no age differences. Ventricular diameter and thickness were similar between the two groups while the atrial area was significantly lower (23.7 ± 6.7 vs. 28.8 ± 8, p

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

    Scientific Electronic Library Online (English)

    Pablo Andrés, Victoria-Gómez.

    2006-09-01

    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 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.

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

    Directory of Open Access Journals (Sweden)

    Pablo Andrés Victoria-Gómez

    2006-09-01

    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.

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

    Science.gov (United States)

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

    1999-01-01

    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

  8. Study of Doppler Shift Correction for Underwater Acoustic Communication Using Orthogonal Signal Division Multiplexing

    Science.gov (United States)

    Ebihara, Tadashi; Mizutani, Keiichi

    2011-07-01

    In this study, we apply Doppler shift correction schemes for underwater acoustic (UWA) communication with orthogonal signal division multiplexing (OSDM) to achieve stable communication in underwater acoustic channels. Three Doppler correction schemes, which exploit the guard interval, are applied to UWA communication with OSDM and evaluated in simulations. Through a simulation in which only the Doppler effect is considered, we confirmed that by adapting schemes to UWA communication with OSDM, we can correct large Doppler shifts, which addresses the usual speed of vehicles and ships. Moreover, by considering both the Doppler effect and channel reverberation, we propose the best possible combination of Doppler correction schemes for UWA communication with OSDM. The results suggest that UWA communication with OSDM may lead to high-quality communication by considering channel reverberation and large Doppler shifts.

  9. Pulsed doppler analysis of human fetal blood flow

    International Nuclear Information System (INIS)

    Echocardiographic imaging techniques have been applied successfully for the diagnosis of structural heart disease in the second- and third-trimester human fetus. These studies have also provided structural information that has increased our understanding of normal fetal cardiac development, had have furthered our concepts of the pathophysiology of congenital heart disease. The application of pulsed Doppler technology for examination of the fetal cardiovascular system offers the promise of increasing our understanding of fetal cardiovascular development, by providing information concerning directional blood flow, as well as estimates of volume flow within the fetus. It is the purpose of this report to review the experience that has been amassed in the application of pulsed Doppler technology for the analysis of blood flow within the human fetus

  10. Color doppler in diagnosis in good-quality formations ovary

    International Nuclear Information System (INIS)

    Parameters of a blood-groove by means of doppler are studied at good-quality tumours and tumours formation of ovary and concentration of oncological marker C A-125 in whey of blood at 32 patients. Research has shown that the method of color doppler allows to spend an estimation of a condition of a vascular channel of bodies of a small basin. Ultrasonic-research, both trans abdominal and trans vaginal it is necessary to use widely for definition of presence or absence of volumetric pathological process in bodies of a small basin and an opportunity of malignant change process. Definition of oncological marker C A-125 at women with presence of tumoral formations testicle should enter into obligatory monitoring inspection in a gynecologic hospital with the purpose of specification of an opportunity of malignant change formations

  11. Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler

    International Nuclear Information System (INIS)

    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 CO2, evidenced by an increase in middle cerebral artery blood flow velocity of 47% ± 15% compared to 28% ± 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 CO2 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

  12. Dove prism based rotating dual beam bidirectional Doppler OCT

    Science.gov (United States)

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

    2013-01-01

    Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to resolve pulsatile retinal absolute blood velocity by performing segment scans around the optic nerve head and circumpapillary scan time series. PMID:23847742

  13. Optical Doppler shift measurement using a rotating mirror

    CERN Document Server

    Bernal, L

    2006-01-01

    Optical Doppler shift demonstration experiments are not a simple task since the light source cannot usually be moved in a sufficiently smooth and uniform manner to keep the level of noise well below of that of the signal. For that reason most demonstration experiments are usually performed with sound or with microwaves. Previous work have been reported using a moving mirror in order to produce a moving light source, but small perturbation of its trajectory, as small as the optical wavelength, can produce a large noise. Using a rotating mirror, in which one beam is reflected from the advancing side and the other beam is reflected from the receding part of a rotating mirror, can overcome many of the noise generating effects. In the present work we report the construction and operation of a demonstration apparatus for measuring optical Doppler shift based on a rotating mirror.

  14. First United Kingdom Doppler Campaign: Results and Interpretation

    Science.gov (United States)

    Ashkenazi, V.; Sykes, R. M.; Gough, R. J.; Williams, J. W.

    1980-01-01

    The first part of the United Kingdom Doppler campaign was carried out in 1976 and involved 13 stations of the primary triangulation network of Great Britain. These were supplemented in 1978 by observations carried out by Decca Survey Limited on seven additional stations, thus covering the whole of the OSGB Network. The observations were processed in the single point positioning mode with both the broadcast ephemeris and the precise ephemeris. All of the data were processed with the use of programs developed at Nottingham. Moreover, and for the sake of comparison, a small sample of the data was also run with several commercially available programs. The analysis of the results indicated some significant discrepancies between the geocentric coordinates obtained by using the two types of ephemeris. These differences were confirmed by similar comparisons carried out on a continental scale. The paper is concluded with practical suggestions aimed at helping organizations processing Doppler data with only the broadcast ephemeris.

  15. A reliable Doppler-based solution for single sensor geolocation

    Science.gov (United States)

    Witzgall, H.

    This paper examines the ability of particle filters to provide accurate Doppler-based frequency of arrival (FOA) geolocation of radio frequency (RF) emitters. Most existing non-differential Doppler geolocation techniques simplify their geolocation solution by assuming that the emitter's carrier frequency is unknown but stable over the course of the triangulation. This assumption is often violated by today's commercial devices whose applications allow for significant carrier frequency drift, with the result of erroneous FOA solutions. The proposed approach uses particles to discretely represent a state's hypothesized emitter location and conditionally updates the particle's associated frequency drift based on that location and the observations. The performance of this approach is examined for the case of a relatively slow-moving unmanned aerial vehicle (UAV). The results show it is significantly more accurate and robust than Newton's iterative gradient descent techniques, and closely approaches the FOA Cramer-Rao lower bound (CRLB) for location estimation.

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

    Science.gov (United States)

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

    2015-03-01

    We propose in this paper the use of Wavelet transform (WT) to detect human falls using a ceiling mounted Doppler range control radar. The radar senses any motions from falls as well as nonfalls due to the Doppler effect. The WT is very effective in distinguishing the falls from other activities, making it a promising technique for radar fall detection in nonobtrusive inhome elder care applications. The proposed radar fall detector consists of two stages. The prescreen stage uses the coefficients of wavelet decomposition at a given scale to identify the time locations in which fall activities may have occurred. The classification stage extracts the time-frequency content from the wavelet coefficients at many scales to form a feature vector for fall versus nonfall classification. The selection of different wavelet functions is examined to achieve better performance. Experimental results using the data from the laboratory and real inhome environments validate the promising and robust performance of the proposed detector. PMID:25376033

  17. Carotid Doppler ultrasound evaluation in patients with pulsatile tinnitus.

    Science.gov (United States)

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

    2015-03-01

    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

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

    DEFF Research Database (Denmark)

    Kjærgaard, Jesper

    2012-01-01

    This thesis summarizes a series of studies performed in order to assess the clinical usefulness of a novel echocardiographic technology that allows non-invasive assessment of regional right ventricular myocardial velocities and deformation: tissue Doppler echocardiography. While the technology is a promising tool for improving our understanding of right ventricular hemodynamics, several aspects of the technology must be evaluated. The accuracy and reproducibility of the technology is evaluated in vitro, and normal values, impact of changes in loading of the right ventricle, response to exercise and pharmacological pulmonary vasodilatation is established in normal subjects. The diagnostic and prognostic importance of adding tissue Doppler echocardiography to conventional echocardiographic and clinical parameters was evaluated in studies on patients with diseases associated with different modes of impact on right ventricular hemodynamics: pulmonary embolism, Arrhythmogenic right ventricular cardiomyopathy and pulmonary regurgitation, the latter in an animal model. The conclusions of the thesis are: Color tissue Doppler echocardiography accurately measures velocities, SR and strain in vitro. No systematic bias between ultrasound systems can be found, and accuracy of the measurements is good. However, the reproducibility of measurements in a test-retest design can limit the usefulness of the technology in daily clinical use, as 25% to 80% of change would be needed for the technology to identify a change in individual patients [I]. Normal values of tissue Doppler based measurements of RV regional velocities, SR and strain exist, and apply to both sexes and in all age groups with the exception of slightly decreasing values in strain with increasing age. Increasing preload and afterload changes regional myocardial velocities, but no changes in SR, strain or isovolumic acceleration could be observed [II and III]. Tissue Doppler echocardiography of the RV free wall in non-massive pulmonary embolism quantifies degree of RVdysfunction, and supports the existence of the McConnell sign of mid-ventricular RV dysfunction. Echocardiographic signs of RV dysfunction are present if > 25% of the pulmonary vascular bed is obstructed. However, Tissue Doppler echocardiography and deformation analysis has no independent value over other clinical and quantitative echocardiographic measures of RV size, pressure and function in these patients [IV and V]. Regional deformation of the RV free wall has significant prognostic importance in a population suspected of first non-massive pulmonary embolism, and is significantly associated with adverse events in patients with proven pulmonary embolism, however, it does not add to the information gained from other quantitative echocardiographic measures of LV and RV function and pressure [VI]. Changes in tissue Doppler based measures of RV systolic function can be used to monitor the effect of selective vasodilation by phosphodiestares-5 inhibition in hypoxic pulmonary hypertension and exercise in normalindividuals. Phosphodiestares-5 inhibition by sildenafil may predominantly be effective during hypoxia in resting conditions, and may improve the blunted response in RV contractility seen with exercise in hypoxia [VII]. Reduced RV free wall deformation can be quantified by tissue Doppler echocardiography in patients with confirmed Arrhythmogenic Right Ventricular Cardiomyopathy, but the clinical application of the technique may be limited by considerable overlap with normal values [VIII]. Acute RV volume loading in free pulmonary regurgitation is associated with abrupt geometric changes in the RV structure including significant dilatation, but is well tolerated with only mild reduction in measures of global RV systolic function as estimated by 2D echocardiography in an experimental animal model. Regional RV myocardial function is also only mildly reduced. Also no differences in global or regional RV function can be observed after 1-3 months of pulmonary regurgitation [IX and X]. Relief of free pulmonary regurg

  19. 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

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

    CERN Document Server

    Zhao, Hongsheng; Li, Baojiu

    2012-01-01

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

  1. Multi-slit spectrograph and H alpha Doppler system

    Science.gov (United States)

    Martin, S. F.; Ramsey, H. E.; Carroll, G. A.; Martin, D. C.

    1974-01-01

    Description of the design and operation of a multiple-entrance-slit spectrograph, built for time-lapse photography of the spectra of flares and other transient solar phenomena. This spectrograph employs narrow-band filters to limit the wavelength range of the spectrograph to a few angstroms centered at H-alpha or other spectral lines. A polarizing beamsplitter, prior to the slits, provides a prefiltered second solar image to a narrow band H-alpha Doppler filter for simultaneous photography in the wings of the H-alpha line. The spectrograph and the H-alpha Doppler system constitute a flexible instrument in which components may be substituted to achieve different passband widths, image scales, dispersions, and corresponding numbers and spacings of adjacent spectra at a selected wavelength.

  2. Doppler shift of laser light reflected from expanding plasmas

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Sun Hui-Xia

    2008-11-01

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

  5. Multipoint photonic doppler velocimetry using optical lens elements

    Science.gov (United States)

    Frogget, Brent Copely; Romero, Vincent Todd

    2014-04-29

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

  6. Planar Doppler Velocimetry for Large-Scale Wind Tunnel Applications

    Science.gov (United States)

    McKenzie, Robert L.

    1998-01-01

    Planar Doppler Velocimetry (PDV) concepts using a pulsed laser are described and the obtainable minimum resolved velocities in large-scale wind tunnels are evaluated. Velocity-field measurements are shown to be possible at ranges of tens of meters and with single pulse resolutions as low as 2 m/s. Velocity measurements in the flow of a low-speed, turbulent jet are reported that demonstrate the ability of PDV to acquire both average velocity fields and their fluctuation amplitudes, using procedures that are compatible with large-scale facility operations. The advantages of PDV over current Laser Doppler Anemometry and Particle Image Velocimetry techniques appear to be significant for applications to large facilities.

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

    CERN Document Server

    Robinson, Michael

    2012-01-01

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

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

    Science.gov (United States)

    Carvalho, Cibele F; Chammas, Maria C

    2011-06-01

    Renal diseases are common in older cats. Decreased renal blood flow may be the first sign of dysfunction and can be evaluated by Doppler ultrasound. But previous studies suggest that the resistive index (RI) has a low sensitivity for detecting renal disease. Doppler waveforms of renal and intrarenal arteries demonstrate decreased blood flow before there are any changes in the RI. The purpose of this study was to evaluate the normal Doppler flowmetrics parameters of renal arteries (RAs), interlobar arteries (IAs) and abdominal aorta (AO) in adult healthy, Persian cats. Twenty-five Persian cats (13 females and 12 males with mean age of 30 months and an age range 12-60 months) with normal clinical examinations and biochemical tests and normal systemic blood pressure were given B-mode ultrasonographies in order to exclude all nephropathies, including polycystic kidney disease. All measurements were performed on both kidneys. Both kidneys (n=50) were examined by color mapping of the renal vasculature. Pulsed Doppler was used to examine both RAs, the IAs at cranial, middle and caudal sites, and the AO. The RI was calculated for all of the vessels. Early systolic acceleration (ESA) of RA and IA was obtained with Doppler spectral analysis. Furthermore, the ratio indices between RA/AO, and IA/RA velocities were calculated. The mean values of peak systolic velocity (PSV) and the diameter for AO were 53.17±13.46 cm/s and 0.38±0.08 cm, respectively. The mean RA diameter for all 50 kidneys was 0.15±0.02 cm. Considering the velocimetric values in both RAs, the mean PSV and RI that were obtained were 41.17±9.40 cm/s and 0.54±0.07. The RA had a mean ESA of 1.12±1.14 m/s(2) and the calculated upper limit of the reference value was 3.40 m/s(2). The mean renal-aortic ratio was 0.828±0.296. The IA showed PSV and RI values of 32.16±9.33 cm/s and 0.52±0.06, respectively. The mean ESA of all IAs was 0.73±0.61 m/s(2). The calculated upper limit of the reference value was 2.0m/s(2). The mean renal-interlobar artery ratio was 1.45±0.57. The RI values obtained in this study were similar to values reported in the literature. Some conditions that lead to a decrease in compliance and to an increase in vascular resistance can affect the Doppler spectral waveforms without changes in RI. To our knowledge, there are no studies that were directed toward to the normal ESA values of the renal vasculature in Persian cats. This study introduced a new ratio between the PSV of the RA and the IA. This index was developed based on the well-known effects of Doppler on the detection of stenosis, regardless of the cause. Further studies are necessary to verify the hemodynamic behavior of this index under pathological conditions in cats as well as the effect of aging, nephropathies and systemic pressure on Doppler velocimetric parameters. PMID:21277819

  9. HF Bistatic Ocean Doppler Spectra: Simulation Versus Experimentation

    OpenAIRE

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

    2013-01-01

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

  10. Scanning Doppler lidar applications for air quality monitoring

    Science.gov (United States)

    Vakkari, Ville; Hirsikko, Anne; O'Connor, Ewan J.; Wood, Curtis R.

    2014-05-01

    Air quality is greatly affected by the sources of gaseous and particulate pollutants, but also by boundary layer dynamics. For instance, a very low mixing layer at the surface can trap emissions at the surface within a smaller volume resulting in higher pollutant concentrations - or it may keep high stack emission from reaching the surface. Additionally, chemical and physical processing of the emissions once in the atmosphere is influenced by turbulent properties of the boundary layer. Scanning Doppler lidars provide a tool for characterising the turbulent nature of the boundary layer and hence we have launched a new project called "Dispersion of air pollution in the boundary layer - new approach with scanning Doppler lidars", which utilises the network of five scanning Doppler lidars (HALO Photonics) operated by the Finnish Meteorological Institute in meteorologically and environmentally different locations in Finland. Vertical wind speed and aerosol backscatter profiles obtained from a Doppler lidar can be used to determine the mixing level height, but only if the mixing layer top exceeds an instrument-specific lower limit, in our case 100 metres. However, low level scanning routines offer possibilities to further decrease this threshold. One of the aims of this project is to combine different scanning routines with vertically pointing measurements and thus decrease the lower threshold for detecting mixing layer height, preferable all the way down to the level of the instrument. On the other hand aerosol backscatter signal from low level scanning can be used to investigate the spatial distribution of particulate matter within the boundary layer. Preliminary comparison of in-situ measurements of PM10 mass concentrations and aerosol backscatter signal over the city of Helsinki indicate that the backscatter signal could be used to provide PM10 mapping over urban regions. The current status of method development for low level mixing height and PM10 mapping as well as subsequent results will be presented in the conference.

  11. Optical Doppler shift measurement using a rotating mirror

    OpenAIRE

    L. Bernal; Bilbao, L.

    2006-01-01

    Optical Doppler shift demonstration experiments are not a simple task since the light source cannot usually be moved in a sufficiently smooth and uniform manner to keep the level of noise well below of that of the signal. For that reason most demonstration experiments are usually performed with sound or with microwaves. Previous work have been reported using a moving mirror in order to produce a moving light source, but small perturbation of its trajectory, as small as the o...

  12. Pulsed Doppler duplex sonography and CT of portal vein thrombosis

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    1997-01-01

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

  14. Doppler velocity assessment of venous return in the human fetus

    OpenAIRE

    Huisman, T. W. A.

    1993-01-01

    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...

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

    OpenAIRE

    Berglund, Andrew J.; Lee, Siu Au; Mcclelland, Jabez J.

    2008-01-01

    We investigate cooling mechanisms in magneto-optically and magnetically trapped erbium. We find efficient sub-Doppler cooling in our trap, which can persist even in large magnetic fields due to the near degeneracy of two Lande g factors. Furthermore, a continuously loaded magnetic trap is demonstrated where we observe temperatures below 25 microkelvin. These favorable cooling and trapping properties suggest a number of scientific possibilities for rare-earth atomic physics, ...

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

    International Nuclear Information System (INIS)

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

  17. Color Doppler Imaging of the Normal Orbital Vessels

    OpenAIRE

    Mehdi Karami; Ahmad Kaviani

    2010-01-01

    Background/Objective: The orbit is one of the most important organs involved in many pathologic conditions. Hemodynamic alterations play an important role in the pathogenesis of some of these conditions such as diabetic retinopathy .Hemodynamic alterations in the orbit may be evaluated by different methods. Color Doppler imaging (CDI) is one of the useful methods that introduces real-time information and is a non-invasive, safe and inexpensive technique. There are few investigations about nor...

  18. Three-dimensional laser cooling at the Doppler limit

    OpenAIRE

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

    2014-01-01

    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...

  19. Three component laser Doppler measurements in an axisymmetric jet

    Science.gov (United States)

    Kuhlmann, John M.; Gross, Robert W.

    1989-01-01

    A three-component laser Doppler anemometer (LDA) was used to acquire a detailed set of three-dimensional mean and fluctuating velocity measurements in a low-speed air jet entering a stagnant ambient, over the first 20 jet exit diameters along the jet trajectory. These data are physically consistent with previous measurements in axisymmetric jets. The relative difficulty of obtaining three-dimensional and two-dimensional LDA data is briefly discussed.

  20. Alignment technique for three-dimensional laser Doppler anemometry

    International Nuclear Information System (INIS)

    Three-dimensional laser Doppler anemometry is a powerful, non-intrusive measurement technique. The high data rate point measurement allows direct quantification of turbulence quantities. However, for this type of study, a very high level of laser beam alignment is required; without good alignment only mean flow measurements are possible. We report here on an alignment procedure that is simple and cost-effective, yet results in much higher data rates than traditional, pinhole-based methods. (technical design note)

  1. Doppler-free Adiabatic Self-Induced Transparency

    OpenAIRE

    Loiko, Yu.; Serrat, C.; Vilaseca, R.; Ahufinger, V.; Mompart, J.; Corbalan, R.

    2009-01-01

    We demonstrate that a Doppler broadened two-level medium can be made transparent to a laser pulse by an appropriate adiabatic variation of the laser field amplitude and its nominal detuning. This new technique of adiabatic self-induced transparency (ASIT) is compared with the well known self-induced transparency (SIT) phenomenon, showing that the adiabatic method is much more robust to variations of the system parameters. We also discuss a possible experimental implementatio...

  2. Exploring shot noise and Laser Doppler imagery with heterodyne holography

    OpenAIRE

    Gross, Michel; Verpillat, Frédéric; Joud, Fadwa; Atlan, Michael

    2012-01-01

    Heterodyne Holography is a variant of Digital Holography, where the optical frequencies of signal and reference arms can be freely adjusted by acousto-optic modulators. Heterodyne Holography is an extremely versatile and reliable holographic technique, which is able the reach the shot noise limit in sensitivity at very low levels of signal. Frequency tuning enables Heterodyne Holography to become a Laser Doppler imaging technique that is able to analyze various kinds of motion.

  3. Novel Applications of Laser Doppler Vibration Measurements to Medical Imaging

    OpenAIRE

    Habib TABATABAI; Oliver, David E.; Rohrbaugh, John W.; Papadopoulos, Christopher

    2013-01-01

    Laser Doppler Vibrometry (LDV) has been widely used in engineering applications involving non-contact vibration and sound measurements. This technique has also been used in some biomedical applications including hearing research. The detectable frequencies are in the range of near-DC to 1 GHz or higher. This paper reviews applications of LDV in biomedical engineering and proposes new medical imaging applications based on measuring surface vibrations of tissues and organs. Tests were conducted...

  4. Proposed pixel for custom laser doppler vibrometry camera

    OpenAIRE

    Jackson, Stephen

    2012-01-01

    Non-destructive testing is an important field of research in many areas of industry and science. This field covers methods that test some property of an object while not impacting its future usefulness. This project is specifically interested in a method of NDE called Laser Doppler Vibrometry (LDV), which uses light to probe the motion of an object's surface. This thesis presents research into the possibility of developing a full-field LDV camera capable of measuring the vibration at a nu...

  5. Vocal fold vibration measurements using laser Doppler vibrometry

    OpenAIRE

    Chan, Alfred; Mongeau, Luc; Kost, Karen

    2013-01-01

    The objective of this study was to measure the velocity of the superior surface of human vocal folds during phonation using laser Doppler vibrometry (LDV). A custom-made endoscopic laser beam deflection unit was designed and fabricated. An in vivo clinical experimental procedure was developed to simultaneously collect LDV velocity and video from videolaryngoscopy. The velocity along the direction of the laser beam, i.e., the inferior-superior direction, was captured. The velocity was synchron...

  6. Low pressure cardiac tamponade: diagnosis facilitated by Doppler echocardiography.

    OpenAIRE

    Hayes, S. N.; Freeman, W. K.; Gersh, B. J.

    1990-01-01

    A case of low pressure cardiac tamponade is reported in which hypovolaemia altered the clinical findings of tamponade and complicated the diagnosis. Venous pressure was not raised and there was no pulsus paradoxus. In this patient, a man of 67, characteristic variations in diastolic inflow signals and the isovolumic relaxation period throughout the respiratory cycle were shown by Doppler echocardiography and led to the diagnosis of cardiac tamponade in the absence of characteristic signs and ...

  7. Computerized Doppler Tomography and Spectrum Analysis of Carotid Artery Flow

    OpenAIRE

    Morton, Paul; Goldman, Dave; Nichols, W. Kirt

    1981-01-01

    Contrast angiography remains the definitive study in the evaluation of atherosclerotic occlusive vascular disease. However, a safer technique for serial screening of symptomatic patients and for routine follow up is necessary. Computerized pulsed Doppler ultrasonic arteriography is a noninvasive technique developed by Miles6 for imaging lateral, antero-posterior and transverse sections of the carotid artery. We [ill] this system with new software and hardware to analyze the three-dimensional ...

  8. Doppler broadening thermometry based on cavity ring-down spectroscopy

    OpenAIRE

    Cheng, C. -f; Wang, J.; Sun, Y. R.; Tan, Y.; Kang, P.; Hu, S. -m

    2015-01-01

    A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to reach a satisfied precision at lower sample pressures, which also reduces the influence due to collisions. By recording the spectrum of C$_2$H$_2$ at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) i...

  9. 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)

  10. Detection of small UAV helicopters using micro-Doppler

    Science.gov (United States)

    Tahmoush, David

    2014-05-01

    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.

  11. Reactive Collision Avoidance for Unmanned Aerial Vehicles using Doppler Radar

    OpenAIRE

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

    2007-01-01

    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 ...

  12. Doppler Echocardiographic Assessment of Pregnant Women with Chronic Arterial Hypertension

    Scientific Electronic Library Online (English)

    Nádia Cristiane de, Mattia; Regina Lúcia, Barbin; Vera Therezinha M., Borges; José Carlos, Peraçoli; Beatriz B., Matsubara.

    2002-12-01

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

  13. Cyclotron autoresonance maser with high Doppler frequency up-conversion

    International Nuclear Information System (INIS)

    A linear induction acceleration (LIA) unit with explosive emission was used as a basis for CARM with high Doppler frequency up-conversion when the wave frequency of elelctrons. Using a high-selective Bragg resonator as an electrodynamic system of CARM we investigated two regimes having essentially different properties: the dispersion characteristics of the electron beam and the wave were either intersected or tangential to one another. 19 refs.; 7 figs

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

    OpenAIRE

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

    2011-01-01

    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...

  15. Online transcranial Doppler ultrasonographic control of an onscreen keyboard

    OpenAIRE

    Jie Lu(IFIC, Universitat de València – CSIC, Apt. Correus 22085, E-46071 València, Spain)

    2014-01-01

    Brain-computer interface (BCI) systems exploit brain activity for generating a control command and may be used by individuals with severe motor disabilities as an alternative means of communication. An emerging brain monitoring modality for BCI development is transcranial Doppler ultrasonography (TCD), which facilitates the tracking of cerebral blood flow velocities associated with mental tasks. However, TCD-BCI studies to date have exclusively been offline. The feasibility of a TCD-based BCI...

  16. Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

    OpenAIRE

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

    2012-01-01

    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 particularly low- or ...

  17. Evaluation of turbulent dissipation rate retrievals from Doppler cloud radar

    OpenAIRE

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

    2012-01-01

    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 ...

  18. Doppler ultrasonographic assessment of uterine arteries during normal canine puerperium.

    Science.gov (United States)

    Batista, P R; Gobello, C; Corrada, Y; Pons, E; Arias, D O; Blanco, P G

    2013-10-01

    The aim of this study was to describe Doppler ultrasonographic changes of uterine arteries during normal canine puerperium. Eight healthy, pure-bred bitches, were ultrasonographically assessed during the postpartum period on Days -3, 3, 10, 17, 24, 38, 52 and 80 (Day 0 defined as the day of parturition). Total horn diameters (TD) and endometrium thickness (E) were evaluated. Color Doppler was used to localize uterine arteries at both sides of the body and pulsed-wave Doppler was performed to obtain the waveforms. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were measured. Resistance index [(PSV-EDV)/PSV] was automatically calculated. Values of TD, E, PSV, EDV and RI were analyzed by repeated measures ANOVA followed by LSD test (SPSS 18.0; SPSS, Chicago, IL, USA). A correlation analysis was also carried out between RI and TD. A progressive decrease of TD (PPSV (P<0.01) and EDV (P<0.01) and an increase of RI (P<0.01) were also found throughout the study period. The resistance index negatively correlated with TD (r=-0.46; P<0.01) and E (r=-0.44; P<0.01) while the ultrasonographic and vascular changes in this period are concurrent with regenerative changes in the glandular and epithelial structures of the uterus. It is concluded that uterine artery RI progressively increased during normal canine puerperium, associated to the two-dimensional ultrasonographic regression of the organ. PMID:23968999

  19. Study of retrobulbar hemodynamics in diabetes via color doppler ultrasound

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2014-09-01

    Full Text Available AIM: To explore the changes of retrobulbar hemodynamics in diabetes via color doppler ultrasound. METHODS: Totally 80 patients(160 eyeswith eye diseases in type 2 diabetes from June 2010 to May 2013 in our hospital were enrolled as research group. By fundus photography and direct ophthalmoscopy, patients were assigned to diabetes without retinopathy group(DNR subgroup, non-proliferative diabetic retinopathy group(NPDR subgroupand proliferative diabetic retinopathy group(PDR subgroup. Of 60 healthy patients(120 eyesover the same period were chosen as control group. The doppler parameters of central retinal artery(CRA, posterior ciliary artery(PCAand ophthalmic artery(OAwere measured.RESULTS: There were significant differences on circulatory parameters of CRA, PCA and OA between both groups(PPPCONCLUSION: The monitoring of retinal blood flow and analysis of blood spectrum morphology via color doppler ultrasound can effectively evaluate the degree of diabetic retinopathy lesions, especially before DR vascular disease. Early detection can reveal the hemodynamic change pattern of DR, facilitating the prevention of diabetic eye complications and improvement of the quality of life.

  20. Diagnostic sensitivity and specificity of Doppler ultrasound in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Terslev, L.; Recke, P. von der

    2008-01-01

    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

  1. Considerations pertinent to the Doppler effect for space reactors

    International Nuclear Information System (INIS)

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

  2. Color doppler flow mapping of prosthetic heart valves

    International Nuclear Information System (INIS)

    Seventy Doppler velocity/flow studies of 23 different types of clinical and preclinical valves were performed after implantation in the mitral position in an animal model system. Sixty-four studies were performed early (0-10) days after implantation and 6 were performed 20 weeks after implantation. Color Doppler velocity/flow profiles were imaged in real-time and with electrocardiographic gating (Aloka system 880). The study protocol included imaging at 10 ms intervals throughout ventricular diastole and systole. Two carrier frequencies (2.5 and 5 MHz) and 3 pulsed repetition frequencies (4, 6 and 8 kHz) were used for a total of 5 maximal resolvable velocities without aliasing from 31 to 121 cm/s overall range of 4 to 121 cm/s). Velocities which aliased in the pulsed modes were quantified utilizing continuous wave Doppler with an independent transducer (Pedoff) or a dual function transducer. Three orthogonal planes were used. Studies were performed at 3 heart rates ranging from 60 - 120/min and at cardiac outputs ranging from 2 - 3.5 1/min, which were within the normal ranges for these animals

  3. Reducing Spaceborne-Doppler-Radar Rainfall-Velocity Error

    Science.gov (United States)

    Tanelli, Simone; Im, Eastwood; Durden, Stephen L.

    2008-01-01

    A combined frequency-time (CFT) spectral moment estimation technique has been devised for calculating rainfall velocity from measurement data acquired by a nadir-looking spaceborne Doppler weather radar system. Prior spectral moment estimation techniques used for this purpose are based partly on the assumption that the radar resolution volume is uniformly filled with rainfall. The assumption is unrealistic in general but introduces negligible error in application to airborne radar systems. However, for spaceborne systems, the combination of this assumption and inhomogeneities in rainfall [denoted non-uniform beam filling (NUBF)] can result in velocity measurement errors of several meters per second. The present CFT spectral moment estimation technique includes coherent processing of a series of Doppler spectra generated in a standard manner from data over measurement volumes that are partially overlapping in the along-track direction. Performance simulation of this technique using high-resolution data from an airborne rain-mapping radar shows that a spaceborne Ku-band Doppler radar operating at signal-to-noise ratios greater than 10 dB can achieve root-mean-square accuracy between 0.5 and 0.6 m/s in vertical-velocity estimates.

  4. Doppler radar wind field retrieval over the Po Valley

    Directory of Open Access Journals (Sweden)

    Y. K. Goh

    2006-01-01

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

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

    International Nuclear Information System (INIS)

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

  6. Advances in Doppler recognition for ground moving target indication

    Science.gov (United States)

    Kealey, Paul G.; Jahangir, Mohammed

    2006-05-01

    Ground Moving Target Indication (GMTI) radar provides a day/night, all-weather, wide-area surveillance capability to detect moving vehicles and personnel. Current GMTI radar sensors are limited to only detecting and tracking targets. The exploitation of GMTI data would be greatly enhanced by a capability to recognize accurately the detections as significant classes of target. Doppler classification exploits the differential internal motion of targets, e.g. due to the tracks, limbs and rotors. Recently, the QinetiQ Bayesian Doppler classifier has been extended to include a helicopter class in addition to wheeled, tracked and personnel classes. This paper presents the performance for these four classes using a traditional low-resolution GMTI surveillance waveform with an experimental radar system. We have determined the utility of an "unknown output decision" for enhancing the accuracy of the declared target classes. A confidence method has been derived, using a threshold of the difference in certainties, to assign uncertain classifications into an "unknown class". The trade-off between fraction of targets declared and accuracy of the classifier has been measured. To determine the operating envelope of a Doppler classification algorithm requires a detailed understanding of the Signal-to-Noise Ratio (SNR) performance of the algorithm. In this study the SNR dependence of the QinetiQ classifier has been determined.

  7. Development of Point Doppler Velocimetry for Flow Field Investigations

    Science.gov (United States)

    Cavone, Angelo A.; Meyers, James F.; Lee, Joseph W.

    2006-01-01

    A Point Doppler Velocimeter (pDv) has been developed using a vapor-limited iodine cell as the sensing medium. The iodine cell is utilized to directly measure the Doppler shift frequency of laser light scattered from submicron particles suspended within a fluid flow. The measured Doppler shift can then be used to compute the velocity of the particles, and hence the fluid. Since this approach does not require resolution of scattered light from individual particles, the potential exists to obtain temporally continuous signals that could be uniformly sampled in the manner as a hot wire anemometer. This leads to the possibility of obtaining flow turbulence power spectra without the limitations of fringe-type laser velocimetry. The development program consisted of a methodical investigation of the technology coupled with the solution of practical engineering problems to produce a usable measurement system. The paper outlines this development along with the evaluation of the resulting system as compared to primary standards and other measurement technologies.

  8. Active Region Moss: Doppler Shifts from Hinode/EIS Observations

    Science.gov (United States)

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

    2012-01-01

    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.

  9. Royal Society, Discussion on the Satellite Doppler Tracking and Its Geodetic Applications, London, England, October 10, 11, 1978, Proceedings

    Science.gov (United States)

    1980-01-01

    The discussion covers variation of Doppler results with software and time, geodetic satellite Doppler positioning and application to Canadian test adjustments, geoid float techniques in satellite geodesy, and the Russian satellite navigation system. Attention is given to topics on improved accuracy from Doppler satellite positioning, Doppler integration intervals and correlation and to terrestrial-Doppler adjustment and analysis of the primary triangulation of Great Britain.

  10. Flujometría Doppler patológica y su correlación con el pronóstico perinatal a corto plazo / Pathologic Doppler velocimetry and correlation with perinatal prognosis at short term

    Scientific Electronic Library Online (English)

    Igor, Huerta; Aída, Borcic.

    Full Text Available Objetivos: Determinar la morbilidad y mortalidad de fetos con flujometría Doppler patológico y evaluar discapacidades en el corto plazo. Diseño: Estudio tipo retrospectivo, observacional, analítico, correlacional. Lugar: Unidad de vigilancia fetal, Hospital Nacional Edgardo Rebagliati Martins, Red A [...] sistencial Rebagliati, EsSalud, Lima, Perú. Participantes: Gestantes con flujometría Doppler patológicos y sus perinatos. Intervenciones: Se estudió todos los casos de gestantes con flujometría Doppler alterado, entre febrero de 2008 y febrero de 2010. Se agrupó por tipos de flujometría Doppler y se describió la frecuencia de patología y morbimortalidad perinatal, correlacionándolas con la edad gestacional. El análisis se realizó con el paquete estadístico SPSS 11,0, la prueba chi cuadrado para las variables discretas y la de Kruskal-Wallis, para las variables continuas. Se asumió un valor de significancia de p Abstract in english Objectives: To determine both morbidity and mortality in fetuses with pathological Doppler velocimetry and short term handicap. Design: Retrospective, observational, analytical, correlation study. Setting: Fetal surveillance unit, Hospital Nacional Edgardo Rebagliati Martins, Red Asistencial Rebagli [...] ati, EsSalud, Lima, Peru. Participants: Pregnant women with pathological Doppler velocimetry and their perinates. Interventions: All pregnant women with altered Doppler velocimetry between February 2008 and February 2010 were studied. They were grouped by Doppler velocimetry types, and frequency of pathology; perinatal morbidity and mortality were determined and correlated with gestational age. SPSS 11,0 was used for statistical analysis, chi square test for discrete variables and Kruskal-Wallis test for continued variables. Significant value was p

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

    Directory of Open Access Journals (Sweden)

    Emmanuelle Tenório Albuquerque Madruga Godoi

    2008-04-01

    Full Text Available 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 clínicas 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.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 characteristics 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.

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

    Scientific Electronic Library Online (English)

    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

    Full Text Available 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.

  13. Conventional and Doppler ultrasonography on a goat with gangrenous mastitis / Ultrassonografia convencional e Doppler em cabra com mastite gangrenosa

    Scientific Electronic Library Online (English)

    V.J.C., Santos; K.M.M.G., Simplício; D.C.C., Sanchez; V.T., Almeida; P.P.M., Teixeira; L.N., Coutinho; L.F.S., Rodrigues; M.E.F., Oliveira; M.A.R., Feliciano; W.R.R., Vicente.

    2014-12-01

    Full Text Available Objetivou-se descrever os achados clínicos e ultrassonográficos de uma cabra leiteira apresentando mastite gangrenosa. Com a ultrassonografia convencional, observaram-se alterações consistentes com o avanço do quadro clínico, como alterações na ecogenicidade do leite e parênquima mamário. A ultrasso [...] nografia Doppler revelou aumento da velocidade de pico sistólico nos três momentos estudados, passando de 15 para 17 e 29cm/s. Houve redução, também, dos valores do índice de resistência, de 0,71 para 0,61 e 0,43. O índice de pulsatividade sofreu redução entre o segundo e o terceiro dia de observação, passando de 0,98 para 0,71. Foi possível estabelecer relação direta entre os achados ultrassonográficos e a gravidade da doença. A ultrassonografia convencional e Doppler podem ser utilizadas para o estudo hemodinâmico do úbere de cabras leiteiras, favorecendo diagnóstico e prognóstico de alterações nesse órgão. Abstract in english [...

  14. Accuracy of doppler ultrasound in diagnosis of endometrial carcinoma

    International Nuclear Information System (INIS)

    Objective: To determine the accuracy of Doppler ultrasound in the diagnosis of endometrial carcinoma in patients presenting with post-menopausal bleeding while taking histopathological findings as the gold standard. Methods: The cross-sectional study was done at the Department of Radiology, Bahawal Victoria Hospital, Bahawalpur, from April 1 to September 30, 2009, and comprised 128 patients above 50 years of age having history of post-menopausal bleeding and who were referred to the department. Name, age and hospital registration number were recorded on a proforma. Doppler ultrasound was performed and endometrial thickness and uterine artery resistive index were recorded on transabdominal ultrasonography. Patients with endometrial thickness of more than 5mm and uterine artery resistive index of less than 0.7 were considered to be having endometrial carcinoma. Histopathology findings were also recorded using the hospital registration number of the patient. The findings of Doppler ultrasound scan were validated with the findings of histopathology. Results: Of the 128 patients, 48 (37.5%) were between the ages of 51 and 55 years; 46 (35.93%) were in the 56-60 age group; and 34 (26.57%) were over 65 years. On the basis of Doppler ultrasound findings, 106 (82.8%) patients were diagnosed as having endometrial carcinoma, while 22 (17.19%) were declared negative. Ultrasonography results were compared with histopathology findings. The percentages of true positive, true negative, false positive and false negative were calculated. There were 103 (80.47%) true positive; 12 (9.37%) false positive; 10 (7.81%) true negative; and 3 (2.35%) false negative. Specificity, sensitivity, positive predictive value and negative predictive value were found to be 97.16%, 76%, 89.56% and 76.92% respectively. Conclusion: The use of Doppler ultrasonography in non-invasive diagnosis of endometrial carcinoma in patients presenting with post-menopausal bleeding was quite useful with good sensitivity, specificity, as well as positive and negative predictive values. There were no procedural complications. (author)

  15. Experimental Study of Doppler Effect for Underwater Acoustic Communication Using Orthogonal Signal Division Multiplexing

    Science.gov (United States)

    Ebihara, Tadashi; Mizutani, Keiichi

    2012-07-01

    This paper is about the underwater acoustic (UWA) communication using orthogonal signal division multiplexing (OSDM) in shallow water, whose environment is time spread and frequency spread. In this paper, the Doppler effect - Doppler shift and spread - for UWA communication using OSDM is mainly considered. The effects of Doppler shift and Doppler spread are evaluated in a test tank with a moving platform on a stable water surface and with a stable platform with a moving water surface, respectively. Doppler shift correction, which has been considered in simulation-based studies, is found to work effectively. In relation to the effect of Doppler spread, the experimental result well agrees with the simulation result. Through this study, it is confirmed that a smaller frame length is preferable because it enables the measurement of the UWA channel frequently so that it can keep up with channel changes.

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

    Scientific Electronic Library Online (English)

    José Alexandre, Mendonça.

    2014-12-01

    Full Text Available 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.

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

    OpenAIRE

    Mouche, Alexis; Collard, Fabrice; Chapron, Bertrand; Dagestad, Knut-frode; Guitton, Gilles; Johannessen, Johnny A.; Kerbaol, Vincent; Hansen, Morten Wergeland

    2012-01-01

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

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

    OpenAIRE

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

    2010-01-01

    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...

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

    OpenAIRE

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

    2012-01-01

    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...

  20. Laser Doppler holographic microscopy in transmission: application to fish embryo imaging

    OpenAIRE

    Verrier, Nicolas; Alexandre, Daniel; Gross, Michel

    2014-01-01

    We have extended Laser Doppler holographic microscopy to transmission geometry. The technique is validated with living fish embryos imaged by a modified upright bio-microcope. By varying the frequency of the holographic reference beam, and the combination of frames used to calculate the hologram, multimodal imaging has been performed. Doppler images of the blood vessels for different Doppler shifts, images where the flow direction is coded in RGB colors or movies showing blo...

  1. Effects of testicular microlithiasis on Doppler parameters: report of three cases

    OpenAIRE

    Alkan Alpay; Baysal Tamer; Sigirci Ahmet; Kutlu Ramazan; Sarac Kaya

    2002-01-01

    Abstract Background Testicular microlithiasis is a rare, usually asymptomatic, non-progressive disease of the testes associated with various genetic anomalies, infertility and testicular tumors. According to our literature search, there is no specific data about Doppler findings in this disease. Case presentation Doppler findings of three cases of testicular microlithiasis during last two years in our institution are presented. Conclusions Although our hypothesis was to find increased Doppler...

  2. Simulated Doppler radar observations of inhomogeneous clouds: Application to the EarthCARE space mission

    OpenAIRE

    Schutgens, NAJ

    2008-01-01

    A new simulation technique for spaceborne Doppler radar observations that was developed specifically for inhomogeneous targets is presented. Cloud inhomogeneity affects Doppler observations in two ways. First, line-of-sight velocities within the instantaneous field of view are unequally weighted. As the large forward motion of a spaceborne radar contributes to these line-of-sight velocities this causes biases in observed Doppler speeds. Second, receiver voltages now have time-varying stochast...

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

    Directory of Open Access Journals (Sweden)

    Sun Huixia

    2014-01-01

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

  4. Study of Doppler waveforms in pregnancy induced hypertension and its correlation with perinatal outcome

    OpenAIRE

    Smitha K; Sowmya K; Malathi T

    2014-01-01

    Background: Objectives of current study were to study the significance of Doppler in PIH using middle cerebral artery and umbilical artery blood flow and to analyze the role of Doppler in PIH in predicting perinatal outcome. Methods: Hundred cases of women with pregnancy induced hypertension between 28-40 weeks of gestation were studied for umbilical artery and middle cerebral artery Doppler waveforms. The perinatal outcome results were documented and analyzed statistically using percentag...

  5. Acoustic Doppler Current Profiling near Myrtle Bend, June 3, 2013, Kootenai River near Bonners Ferry, ID

    U.S. Geological Survey, Department of the Interior — Acoustic doppler current profiling (ADCP) data was collected to describe streamflow characteristics including total streamflow, velocity magnitude and secondary...

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

    CERN Document Server

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

    2007-01-01

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

  7. Sub-Doppler Laser Cooling of Thulium Atoms in a Magneto-optical Trap

    OpenAIRE

    Sukachev, D.; A. Sokolov; Chebakov, K.; Akimov, A.; Kanorsky, S.; Kolachevsky, N.; Sorokin, V

    2010-01-01

    We have experimentally studied sub-Doppler laser cooling in a magneto-optical trap for thulium atoms working at the wavelength of 410.6\\,nm. Without any dedicated molasses period of sub-Doppler cooling, the cloud of $3\\times 10^6$ atoms at the temperature of 25(5)\\,$\\mu$K was observed. The measured temperature is significantly lower than the Doppler limit of 240$\\mu$K for the cooling transition at 410.6\\,nm. High efficiency of the sub-Doppler cooling process is due to a near...

  8. Effects of testicular microlithiasis on Doppler parameters: report of three cases

    Directory of Open Access Journals (Sweden)

    Alkan Alpay

    2002-02-01

    Full Text Available Abstract Background Testicular microlithiasis is a rare, usually asymptomatic, non-progressive disease of the testes associated with various genetic anomalies, infertility and testicular tumors. According to our literature search, there is no specific data about Doppler findings in this disease. Case presentation Doppler findings of three cases of testicular microlithiasis during last two years in our institution are presented. Conclusions Although our hypothesis was to find increased Doppler parameters due to intratesticular arterial compression, our findings suggest that there are no Doppler findings specific to testicular microlithiasis.

  9. UARS High Resolution Doppler Imager (HRDI) Level 3AL V001

    National Aeronautics and Space Administration — The High Resolution Doppler Imager (HRDI) on NASA's Upper Atmosphere Research Satellite (UARS) measures winds and other parameters in the mesosphere and lower...

  10. UARS High Resolution Doppler Imager (HRDI) Level 3AT V001

    National Aeronautics and Space Administration — The High Resolution Doppler Imager (HRDI) on NASA's Upper Atmosphere Research Satellite (UARS) measures winds and other parameters in the mesosphere and lower...

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

    Directory of Open Access Journals (Sweden)

    D. van Dinther

    2014-07-01

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

  12. Global Doppler frequency shift detection with near-resonant interferometry

    Science.gov (United States)

    Landolt, Andrin; Roesgen, Thomas

    2009-10-01

    The recent development in measuring 2D Doppler shift distributions for flow velocimetry using the dispersive properties of atomic line filters is presented. On the basis of velocity field measurements on a subsonic jet flow and a tip vortex flow in a medium-sized wind tunnel, the technique was assessed. Atomic line filters near a resonant transition combine imaging capabilities with a sharp frequency cutoff and an associated region of strong anomalous dispersion. While conventional Doppler global velocimetry relies on the absorption of the filter to convert frequency shifts to intensity variations, near-resonant interferometry uses its dispersion to detect frequency shifts as phase changes in an interference pattern. In the present setup, an iodine vapor cell in an imaging Michelson interferometer is used. With the illuminating laser frequency tuned near a resonant transition, the cell’s dispersion converts the frequency content of the field of view into a distortion of the carrier-fringe pattern recorded at the image plane of the interferometer. The phase distribution in the fringe images is reconstructed by filtering the individual images with a 2D Gabor filter pair tuned to the spatial frequencies of the basic carrier-fringe pattern. The post-processing is concluded with subsequent phase-unwrapping and subtraction of the carrier reference fringe phase. The method and the setup were demonstrated and calibrated experimentally on a rotating disc. The capability of the technique to operate in a real experimental environment was validated in a free subsonic jet and a tip vortex flow behind a wing section in a medium-sized wind tunnel facility. The measurements were found to be in generally good agreement with the theoretically predicted system characteristics and the reference measurements. As with other Doppler global techniques, the stability of the pulsed laser system and the secondary scattering in the test volume were identified as the main error sources.

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

    International Nuclear Information System (INIS)

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

  14. Turbulence Spectra from Doppler-shifted Spectral Lines

    International Nuclear Information System (INIS)

    Turbulence is a key element of the dynamics of astrophysical fluids, including those of interstellar medium, clusters of galaxies and circumstellar regions. Turbulent motions induce Doppler shifts of observable emission and absorption lines. In the review we discuss new techniques that relate the spectra of underlying velocity turbulence and spectra of Doppler-shifted lines. In particular, the Velocity-Channel Analysis (VCA) makes use of the channel maps, while the Velocity Coordinate Spectrum (VCS) utilizes the fluctuations measured along the velocity axis of the Position-Position Velocity (PPV) data cubes. Both techniques have solid foundations based on analytical calculations as well as on numerical testings. Among the two the VCS, which has been developed quite recently, has two advantages. First of all, it is applicable to turbulent volumes that are not spatially resolved. Second, it can be used with absorption lines that do not provide good spatial sampling of different lags over the image of turbulent object. In fact, numerical testing shows that measurements of Doppler shifted absorption lines over a few directions is sufficient for a reliable recovering of the underlying spectrum of the turbulence. Our comparison of the VCA and the VCS with a more traditional technique of Velocity Centroids, shows that the former two techniques recover reliably the spectra of supersonic turbulence, while the Velocity Centroids may have advantages for studying subsonic turbulee advantages for studying subsonic turbulence. In parallel with theoretical and numerical work on the VCA and the VCS, the techniques have been applied to spectroscopic observations. We discuss results on astrophysical turbulence obtained with the VCA and the VCS

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-06-01

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

  16. 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)

  17. Investigation of Frequency Analysis Methods for Doppler Ultrasound Systems

    Directory of Open Access Journals (Sweden)

    Tatsuro Baba

    2013-03-01

    Full Text Available Due to the advances of electronic and semiconductor technologies in recent years, it is possible to realize complex, low cost, low size, and low power consumption, high-speed signal processing devices. The progress of these devices has enabled the development of the medical Doppler ultrasound system. Color flow mapping (CFM, which is one of the display mode of Doppler ultrasound, requires high-speed multi-point (two- or three-dimensional frequency analyses. From its birth till today, a complex autocorrelation (AC method has been used for CFM because of its simplicity. In this paper, I propose the fast Fourier transform (FFT method for the frequency analysis of CFM. CFM differs from spectrum Doppler, which shows accurate information of the blood flow in a narrow domain of a tomogram image. CFM uses color expression to display coarse information of the blood flow, such as mean velocity, intensity, and distribution. Because the calculation load of the frequency analysis is very small, the AC method has been used. However, by exploiting recent advances in hardware, new frequency analysis methods can be applied. In this paper, I evaluate a novel frequency analysis method based on FFTs, and compare its performance with the conventional AC method. Based on the results obtained, I reach the followings conclusions. With respect to mean velocity, the FFT method performs well when blood flow sensitivity is low. However, when blood flow sensitivity is high, the performance of the AC method is superior. Moreover, with respect to the distribution, compared to the FFT method, the AC method does not perform well under aliasing conditions. The AC method is effective only when the distribution is small.

  18. Implementation of on-the-fly doppler broadening in MCNP

    International Nuclear Information System (INIS)

    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)

  19. Coherent Doppler Laser Radar: Technology Development and Applications

    Science.gov (United States)

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

    2000-01-01

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

  20. Duplex Color Doppler Sonogram of the Orbital Diseases

    International Nuclear Information System (INIS)

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

  1. A Doppler dimming determination of coronal outflow velocity

    Science.gov (United States)

    Strachan, Leonard; Kohl, John L.; Weiser, Heinz; Withbroe, George L.; Munro, Richard H.

    1993-01-01

    Outflow velocities in a polar coronal hole are derived from observations made during a 1982 sounding rocket flight. The velocity results are derived from a Doppler dimming analysis of resonantly scattered H I Ly-alpha. This analysis indicates radial outflow velocities of 217 km/s at 2 solar radii from sun-center with an uncertainty range of 153 to 251 km/s at a confidence level of 67 percent. These results are best characterized as strong evidence for supersonic outflow within 2 solar radii of sun-center in a polar coronal hole. Several means for obtaining improved accuracy in future observations are discussed.

  2. Sub-Doppler Laser Cooling of Fermionic K-40 Atoms

    CERN Document Server

    Modugno, G; Hannaford, P; Roati, G; Inguscio, M

    1999-01-01

    We report laser cooling of fermionic K-40 atoms, with temperatures down to (15 +/- 5) microK, for an enriched sample trapped in a MOT and additionaly cooled in optical molasses. This temperature is a factor of 10 below the Doppler-cooling limit and corresponds to an rms velocity within a factor of two of the lowest realizable rms velocity (~3.5v rec) in 3D optical molasses. Realization of such low atom temperatures, up to now only accessible with evaporative cooling techniques, is an important precursor to producing a degenerate Fermi gas of K-40 atoms.

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

    CERN Document Server

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

    2002-01-01

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

  4. Doppler monitoring of middle cerebral artery emboli from carotid stenoses.

    Science.gov (United States)

    Müller, H R; Lyrer, P; Boccalini, P

    1995-04-01

    The aim of this study was to prove the existence of clinically silent embolization arising from carotid stenoses. Simultaneous bilateral transcranial Doppler sonography of the middle cerebral artery was carried out during 10 minutes in 30 patients having ultrasonically demonstrated unilateral (n = 12) or bilateral internal carotid stenoses (n = 18). Twenty-four of the stenoses were clinically considered to be symptomatic and 24 were asymptomatic. Emboli signals were detected in 5 of the 30 patients. All occurred unilaterally on the side of a high-grade carotid stenosis. Four of the 5 lesions were symptomatic, and 1 was asymptomatic. PMID:7718944

  5. Doppler lidar measurement of profiles of turbulence and momentum flux

    Science.gov (United States)

    Eberhard, Wynn L.; Cupp, Richard E.; Healy, Kathleen R.

    1989-01-01

    A short-pulse CO2 Doppler lidar with 150-m range resolution measured vertical profiles of turbulence and momentum flux. Example measurements are reported of a daytime mixed layer with strong mechanical mixing caused by a wind speed of 15 m/sec, which exceeded the speed above the capping inversion. The lidar adapted an azimuth scanning technique previously demonstrated by radar. Scans alternating between two elevation angles allow determination of mean U-squared, V-squared, and W-squared. Expressions were derived to estimate the uncertainty in the turbulence parameters. A new processing method, partial Fourier decomposition, has less uncertainty than the filtering used earlier.

  6. Doppler Compensation by using of Segmented Match Filter

    OpenAIRE

    Nader Ghadimi; Mohammad Jabbariani; Hosein Khaleghi-Bizaki

    2008-01-01

    Match filter is one of the important parts of radar receiver. By using of Match Filter, the signal to noise ratio can be maximized so that the probability of detection is increased. Match Filter can be used as a pulse compression filter in radar receiver. Binary phase code is one of the pulse compression methods that, the compression can be down with a Match Filter in the receiver. Doppler effect is one of the problems that degrade the performance of Match Filter. In this paper, two methods ?...

  7. Holographic laser Doppler imaging of pulsatile blood flow

    CERN Document Server

    Bencteux, Jeffrey; Kostas, Thomas; Bayat, Sam; Atlan, Michael

    2015-01-01

    We report on wide-field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real-time. Optical Doppler images were measured with green laser light by a frequency-shifted Mach-Zehnder interferometer in off-axis configuration. The recorded optical signal was linked to local instantaneous out-of-plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood pulse monitored by plethysmoraphy during an occlusion-reperfusion experiment.

  8. Analysis of fine structure in Doppler broadened annihilation peaks

    International Nuclear Information System (INIS)

    A Doppler annihilation spectra general unfolding algorithm was developed. This general algorithm has two programs: (i) RESFIT for fitting of the detector system resolution function; and (ii) DPPUNFOL for unfolding the experimental annihilation spectra. It should be mentioned that the asymmetric characteristic of this kind of spectra was considered as a part of the resolution function, instead of including it into the background. Both programs were tested using modeled data with statistical noise from 1- to 3-sigma levels added. A good agreement between the 'true' parameters and the unfolded ones was achieved for all studied cases. (author)

  9. Wind climatology observed over Kalpakkam using Doppler sodar

    International Nuclear Information System (INIS)

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

  10. Numerical computation of doppler-broadening in the resonance domain

    International Nuclear Information System (INIS)

    We have implemented an accurate and fast calculation of the Doppler-broadened kernel PT(E ? E') for neutron elastic scattering based on a gas model. An exponential cutoff which accounts for the asymptotic behavior of the error function helps limit the range of integration while eliminating difference effects. This allows for calculating a kernel library for 238U over a very fine energy grid covering the resonance range in only a few hours in a laptop. We give an example showing the impact of 238U elastic up-scattering on the values of self shielded cross sections. (authors)

  11. Sub-Doppler Laser Cooling of Fermionic K-40 Atoms

    OpenAIRE

    Modugno, G.; Benko, C.; Hannaford, P.; Roati, G.; Inguscio, M.

    1999-01-01

    We report laser cooling of fermionic K-40 atoms, with temperatures down to (15 +/- 5) microK, for an enriched sample trapped in a MOT and additionaly cooled in optical molasses. This temperature is a factor of 10 below the Doppler-cooling limit and corresponds to an rms velocity within a factor of two of the lowest realizable rms velocity (~3.5v rec) in 3D optical molasses. Realization of such low atom temperatures, up to now only accessible with evaporative cooling techniqu...

  12. CFAR analysis for medium PRF airborne pulse Doppler radars

    Science.gov (United States)

    Ye, Zhenru; Zhu, Zhaoda; Huang, Xinping

    MTI-FFT-frequency cell-averaging CFAR processors are discussed. The assumption that the clutter samples in the test cell and the reference cells are independent and identically distributed (IID) is shown to be no longer valid for the frequency cell-averaging CFAR processor in medium PRF airborne pulse Doppler radars. A hybrid method of analytical computation and Monte-Carlo simulation for quantifying the processor performance is described. The effect of various MTI cancelers and weighting forms on the detection performance under different conditions of clutter is analyzed.

  13. Sub-Doppler modulation spectroscopy of potassium for laser stabilization

    International Nuclear Information System (INIS)

    We study modulation spectroscopy of the potassium D2 transitions at 766.7 nm. The vapour pressure, controlled by heating a commercial reference cell, is first optimized using conventional saturated absorption spectroscopy. Heterodyne detection then 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. (paper)

  14. Wind Doppler lidar with 1.5 ?m fiber laser

    International Nuclear Information System (INIS)

    Compact Doppler lidar with monostatic receiving geometry has been developed and tested. Laser source of the lidar is continuous wave fiber laser ELD-1000 with 1.5 ?m wavelength and 1 W output. For distances up to 100 m the range of measurable wind velocities is 1.5 – 20 m/s. Results obtained show that performance conditions for the lidar corresponds to the visibility range up to 1 km. Sonic vibrations with small amplitudes (? 10 nm) of remote targets with diffuse reflection has been registered by this device at distances up to 60 m

  15. Holographic laser Doppler imaging of pulsatile blood flow

    OpenAIRE

    Bencteux, Jeffrey; Pagnoux, Pierre; Kostas, Thomas; Bayat, Sam; Atlan, Michael

    2015-01-01

    We report on wide-field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real-time. Optical Doppler images were measured with green laser light by a frequency-shifted Mach-Zehnder interferometer in off-axis configuration. The recorded optical signal was linked to local instantaneous out-of-plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood p...

  16. Reynolds stress measurements in cylindrical geometry using laser Doppler anemometry

    International Nuclear Information System (INIS)

    Two-component one-point velocity correlation measurements in a cylindrical test section were performed using two-color Laser Doppler anemometry (LDA). In order to overcome the severe optical distortion effects in cylindrical geometry and achieve two-color spatial coincidence, two experimental methods were used: (1) attaching a rectangular, fluid-filled box to the pipe exterior; and (2) employing a laser-beam translating device. A description of these methods and some examples of coincidence data taken in pipe flow are presented

  17. Laser doppler measurements of flow in a rod bundle

    International Nuclear Information System (INIS)

    A two component laser doppler velocimeter with polarized beams and frequency shift was used to measure the turbulent flow field for axial flow between the rods of a nine rod, square pitch rod bundle. Parameters measured include mean axial and lateral velocities, turbulence intensities and the friction factor. The axial velocities for 10 000 to 40 000 Reynolds number are slightly higher than those reported by Rowe. The maximum lateral velocities measured are about 1% of the bulk velocity; somewhat larger than suggested by earlier authors. Axial and lateral turbulence intensities are larger than those in pipe flows. (orig.)

  18. Short-time Fourier transform laser Doppler holography

    OpenAIRE

    Samson, Benjamin; Atlan, Michael

    2012-01-01

    We report a demonstration of laser Doppler holography at a sustained acquisition rate of 250 Hz on a 1 Megapixel complementary metal-oxide-semiconductor (CMOS) sensor array and image display at 10 Hz frame rate. The holograms are optically acquired in off-axis configuration, with a frequency-shifted reference beam. Wide-field imaging of optical fluctuations in a 250 Hz frequency band is achieved by turning time-domain samplings to the dual domain via short-time temporal Four...

  19. Sub-Doppler laser spectroscopy of small molecules

    International Nuclear Information System (INIS)

    Three different techniques of laser spectroscopy with sub-Doppler resolution are discussed which have been applied to the investigation of diatomic and triatomic molecules. These are linear laser spectroscopy in collimated molecular beams, polarization spectroscopy and a combination of both methods with optical-optical double resonance techniques. The methods are illustrated by high resolution spectra of the molecules NaK, Cs2 and NO2. A section on time resolved spectroscopy, applied to lifetime measurements and to the determination of collision induced relaxation processes concludes the paper. (orig.)

  20. Spinning disk calibration method and apparatus for laser Doppler velocimeter

    Science.gov (United States)

    Snyder, P. K. (inventor)

    1986-01-01

    A method and apparatus for calibrating laser Doppler velocimeters having one or more intersecting beam pairs are described. These velocimeters measure fluid velocity by observing the light scattered by particles in the fluid stream. Moving fluid particulates are simulated by fine taut wires that are radially mounted on a disk that is rotated at a known velocity. The laser beam intersection locus is first aimed at the very center of the disk and then the disk is translated so that the locus is swept by the rotating wires. The radial distance traversed is precisely measured so that the velocity of the wires (pseudo particles) may be calculated.

  1. Fiber optic laser Doppler anemometry in swirling jets

    Science.gov (United States)

    Taghavi, R.; Rice, E. J.

    1991-01-01

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

  2. Hardening Doppler Global Velocimetry Systems for Large Wind Tunnel Applications

    Science.gov (United States)

    Meyers, James F.; Lee, Joseph W.; Fletcher, Mark T.; South, Bruce W.

    2004-01-01

    The development of Doppler Global Velocimetry from a laboratory curiosity to a wind tunnel instrumentation system is discussed. This development includes system advancements from a single velocity component to simultaneous three components, and from a steady state to instantaneous measurement. Improvements to system control and stability are discussed along with solutions to real world problems encountered in the wind tunnel. This on-going development program follows the cyclic evolution of understanding the physics of the technology, development of solutions, laboratory and wind tunnel testing, and reevaluation of the physics based on the test results.

  3. Holographic laser Doppler imaging of pulsatile blood flow

    Science.gov (United States)

    Bencteux, Jeffrey; Pagnoux, Pierre; Kostas, Thomas; Bayat, Sam; Atlan, Michael

    2015-06-01

    We report on wide-field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real-time. Optical Doppler images were measured with green laser light by a frequency-shifted Mach-Zehnder interferometer in off-axis configuration. The recorded optical signal was linked to local instantaneous out-of-plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood pulse monitored by plethysmoraphy during an occlusion-reperfusion experiment.

  4. SIRHEN : a data reduction program for photonic Doppler velocimetry measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Dolan, Daniel H., III; Ao, Tommy

    2010-06-01

    SIRHEN (Sandia InfraRed HEtrodyne aNalysis) is a program for reducing data from photonic Doppler velocimetry (PDV) measurements. SIRHEN uses the short-time Fourier transform method to extract velocity information. The program can be run in MATLAB (2008b or later) or as a Windows executable. This report describes the new Sandia InfraRed HEtrodyne aNalysis program (SIRHEN; pronounced 'siren') that has been developed for efficient and robust analysis of PDV data. The program was designed for easy use within Sandia's dynamic compression community.

  5. A novel photonic Doppler velocimetry for transverse velocity measurement

    Science.gov (United States)

    Chen, Guanghua; Wang, Detian; Liu, Jun; Meng, Jianhua; Liu, Shouxian; Yang, Qingguo

    2013-01-01

    A fiber interferometry for transverse velocity measurement has been developed. This diagnostic is similar to photonic Doppler velocimetry in the way in which laser propagates and couples. The interferometer mainly consists of a fiber coupler, an emitting probe, and two receiving probes. A pair of scattered laser beams mix in the coupler and generates fringes with frequency proportional to transverse velocity. Measurement of transverse velocity is independent of longitudinal velocity. The feasibility of the technique has been verified by rotating wheel experiment and shock loading experiment.

  6. Effect of window reflections on photonic Doppler velocimetry measurements

    International Nuclear Information System (INIS)

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

  7. A novel photonic Doppler velocimetry for transverse velocity measurement

    International Nuclear Information System (INIS)

    A fiber interferometry for transverse velocity measurement has been developed. This diagnostic is similar to photonic Doppler velocimetry in the way in which laser propagates and couples. The interferometer mainly consists of a fiber coupler, an emitting probe, and two receiving probes. A pair of scattered laser beams mix in the coupler and generates fringes with frequency proportional to transverse velocity. Measurement of transverse velocity is independent of longitudinal velocity. The feasibility of the technique has been verified by rotating wheel experiment and shock loading experiment.

  8. Color Doppler Imaging of Cardiac Catheters Using Vibrating Motors

    OpenAIRE

    Reddy, Kalyan E.; Light, Edward D.; Rivera, Danny J.; Kisslo, Joseph A.; Smith, Stephen W.

    2008-01-01

    We attached a miniature motor rotating at 11,000 rpm onto the proximal end of cardiac electrophysiological (EP) catheters in order to produce vibrations at the tip which were then visualized by color Doppler on ultrasound scanners. We imaged the catheter tip within a vascular graft submerged in a water tank using the Volumetrics Medical Imaging 3D scanner, the Siemens Sonoline Antares 2D scanner, and the Philips ie33 3D ultrasound scanner with TEE probe. The vibrating catheter tip was visuali...

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

    International Nuclear Information System (INIS)

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

  10. Application of coincidence Doppler broadening spectroscopy to simple hydrocarbons

    International Nuclear Information System (INIS)

    Three simple hydrocarbons: methane, ethane, and ethylene in solid state at the temperature of liquid nitrogen were studied by coincidence Doppler-broadening (CDB) spectroscopy and positron annihilation lifetime spectroscopy (PALS). Difference in the momentum distributions of ?- and ?-bond electrons was observed by CDB spectroscopy. Breaking of the weak ?-bonds in ethylene due to the positron irradiation and trapping of positrons by anion molecules and/or anion radicals cause inhibition in the Ps formation in ethylene observed by PALS. The breaking of the ?-bonds in ethylene was detected also as a significant change in the shape of ethylene to methane CDB ratio with the elapsed experiment time

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

    OpenAIRE

    Marcos Valério Coimbra Resende; Marcelo Luiz Campos Vieira; Fernando Bacal; José Lázaro de Andrade; Stolf, Noedir A.; Edmar Alcides Bocchi

    2011-01-01

    FUNDAMENTO: A biópsia endomiocárdica (BEM) é o método padrão-ouro para o diagnóstico de rejeição celular (RC) após transplante cardíaco (TC). OBJETIVO: Testar a hipótese de que o exame de imagem por Doppler tecidual (IDT) pode detectar RC > 3A e agregar informação diagnóstica, comparado ao Doppler convencional. MÉTODOS: Cinquenta e quatro pacientes com TC foram submetidos à BEM e estudo ecocardiográfico através de IDT em até 24 horas. Comparamos os pacientes com TC e RC > 3...

  12. Corruption of radio metric Doppler due to solar plasma dynamics: S/X dual-frequency Doppler calibration for these effects

    Science.gov (United States)

    Winn, F. B.; Reinbold, S. R.; Yip, K. W.; Koch, R. E.; Lubeley, A.

    1975-01-01

    Doppler data from Mariner 6, 7, 9, and 10 and Pioneer 10 and 11 were discussed and the rms noise level for various sun-earth-probe angles were shown. The noise levels of both S- and X-band Doppler data for sun-earth-probe angles smaller than 20 deg were observed to be orders of magnitude greater than nominal. Such solar plasma-related Doppler degradation reduced the Mariner 10-Mercury 11 encounter navigation accuracy by nearly a factor of 10. Furthermore, this degradation was shown to be indirectly related to plasma dynamics and not a direct measure of the dynamics.

  13. Precision of laser Doppler scanning in clinical use.

    Science.gov (United States)

    Stücker, M; Heese, A; Hoffmann, K; Röchling, A; Altmeyer, P

    1995-09-01

    Reactions of the cutaneous microcirculation to local stimuli have been quantitated in terms of area of erythema (planimetry), change in colour (colorimetry) and time-dependent changes in perfusion (one-dimensional laser Doppler fluxmetry (LDF)). Using the new technique of laser Doppler scanning (LDS) it is now possible to quantify and demonstrate two-dimensional patterns of microvascular perfusion in terms of intensity and extent. The precision of this new technique was compared with the previously established techniques by examining the reactions of 15 healthy volunteers to the intracutaneous injection of carbacholin and isotonic NaCl solutions. Both stimuli were applied paravertebrally, on the left and right side. Reactions were examined after 10 min. As a control for temporal reproducibility the examination was repeated on another day. All methods allowed the differentiation of reactions to carbacholin from those to NaCl (P or = 0.78). Using LDF or planimetry, reproducibility of values was lower (r or = 0.77). Hyperaemic areas seen with LDS were significantly larger than those determined by planimetry. Results of LDS are reproducible spatially and temporally: the technique will allow time-course observations of skin reactions that are accompanied by medium-term changes in perfusion. PMID:8593712

  14. Color Doppler Ultrasonographic Features of Hashimoto's Thyroiditis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joo Hyuk; Kim, Mie Young; Rho, Eun Jin; Yi, Jeong Geun; Han, Chun Hwan [Kangnam General Hospital Public Corporation, Seoul (Korea, Republic of); Hwang, Hee Yong [Choong Ang Gil Hospital, Incheon (Korea, Republic of)

    1995-06-15

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

  15. Hypercholesterolemia and Myocardial function evaluated via Tissue Doppler Imaging

    Directory of Open Access Journals (Sweden)

    Kotaru Pavan

    2009-11-01

    Full Text Available Abstract Objective To establish a link between hypercholesterolemia and myocardial dysfunction. Background Heart failure is a complex disease involving changes in systolic and diastolic function. Newer echocardiographic imaging modalities may be able to detect discreet changes in myocardial function associated with hypercholesterolemia. Therefore we sought to establish a link between hypercholesterolemia and myocardial dysfunction with tissue Doppler imaging (TDI. Methods Twenty-seven rabbits were studied: 7 were fed normal chow (group 1 and 20 a high cholesterol diet (10 with ezetimibe, 1 mg/kg/day; group 2 and 10 without, group 3. Echocardiographic images were obtained under general anesthesia. Serum cholesterol levels were obtained at baseline, 3 and 6 months and myocardial cholesterol levels measured following euthanasia. Results Doppler measurements, including E/A, E'/A' and S' were significantly lower in group 3 compared to both groups 1 and 2 but no significant differences were noted in chamber sizes or ejection fraction among the groups. Average serum cholesterol was higher in group 3 compared to groups 1 and 2 respectively (495 ± 305 mg/dl vs. 114 ± 95 mg/dl and 87 ± 37 mg/dl; p 2 = 0.17 p = 0.04, r2 = 0.37 p = 0.001 and r2 = 0.24 p = 0.01. Conclusion Cholesterol load in the serum and myocardium was significantly associated with decreased systolic and diastolic function by TDI. Moreover, lipid lowering was protective.

  16. Color-flow Doppler sonography in Graves disease: "thyroid inferno".

    Science.gov (United States)

    Ralls, P W; Mayekawa, D S; Lee, K P; Colletti, P M; Radin, D R; Boswell, W D; Halls, J M

    1988-04-01

    Graves disease is a common diffuse abnormality of the thyroid gland usually characterized by thyrotoxicosis. We performed color-flow Doppler sonography in 16 patients with Graves disease and compared the results with those in 15 normal volunteers and 14 patients with other thyroid diseases (eight with multinodular goiter, four with focal masses, and two with papillary thyroid carcinoma). All 16 Graves disease patients exhibited a pulsatile pattern we call "thyroid inferno." This pattern consists of multiple small areas of intrathyroidal flow seen diffusely throughout the gland in both systole and diastole. In systole, both high-velocity flow (color coded white) and lower velocity flow (color coded red and blue) were noted. In diastole, fewer areas of flow and lower velocity flow were noted. Patients with Graves disease also exhibited color flow around the periphery of the gland. The inferno pattern did not occur in normal subjects or in patients with other thyroid diseases. On occasion, focal areas of intrathyroidal flow were detected in patients with multinodular goiter and focal thyroid masses. High-resolution gray-scale images did not show the small vascular channels from which the flow signal originated. Color-flow Doppler sonography shows promise as a cost-effective, noninvasive technique for diagnosing Graves disease. PMID:3279732

  17. Intrinsic physical properties and Doppler boosting effects in LSI+61303

    CERN Document Server

    Massi, M

    2014-01-01

    Our aim is to show how variable Doppler boosting of an intrinsically variable jet can explain the long-term modulation of 1667 \\pm 8 days observed in the radio emission of LSI+61303. The physical scenario is that of a conical, magnetized plasma jet having a periodical (P1) increase of relativistic particles, Nrel, at a specific orbital phase, as predicted by accretion in the eccentric orbit of LSI+61303. Jet precession (P2) changes the angle, eta, between jet axis and line of sight, thereby inducing variable Doppler boosting. The problem is defined in spherical geometry, and the optical depth through the precessing jet is calculated by taking into account that the plasma is stratified along the jet axis. The synchrotron emission of such a jet was calculated and we fitted the resulting flux density Smodel(t) to the observed flux density obtained during a 6.5-year monitoring of LSI+61303 by the Green Bank radio interferometer. Our physical model for the system LSI+61303 is not only able to reproduce the long-te...

  18. Velocimetría Doppler de las arterias uterinas en el embarazo

    Directory of Open Access Journals (Sweden)

    H\\u00E9ctor Pe\\u00F1a Dehesa

    2008-01-01

    Full Text Available El ultrasonido Doppler es una técnica no invasora usada comúnmente para la evaluación hemodinámica y fetal. El embarazo incrementa de forma considerable la circulación uterina, misma que favorece el adecuado crecimiento fetal. Los cambios vasculares que ocurren en la circulación uterina, provocados por el embarazo, se deben a la pérdida de los componentes elásticos y musculares de las arterias espirales, merced a la invasión trofoblástica y su reemplazo por tejido fibrinoide. La forma de la onda de velocidad de flujo de la arteria uterina es única; se distingue por una velocidad alta al final de la diástole y flujo continuo durante la misma. En el transcurso del embarazo, y hasta su término, el flujo aumenta constantemente. La falla en la invasión de las arterias espirales por el trofoblasto resulta en una mayor resistencia vascular uterina, con disminución de la perfusión a través de la placenta, lo que puede llevar a restricción del crecimiento intrauterino y finalmente ocasionar preeclampsia. El Doppler de la arteria uterina sirve como una forma de rastreo para identificar el riesgo de sufrir algunas enfermedades o para predecir con alto grado de certeza el desarrollo de un embarazo sin estas complicaciones. De ninguna manera evalúa la salud fetal ni determina la implantación de conductas obstétricas.

  19. An acoustic spanner and its associated rotational Doppler shift

    International Nuclear Information System (INIS)

    Light carries a spin angular momentum associated with its polarization and an orbital angular momentum arising from its phase cross-section. Sound, being a longitudinal wave, carries no spin component but can carry an orbital component of angular momentum when endowed with an appropriate phase structure. Here, we use a circular array of loudspeakers driven at a common angular frequency ?s but with an azimuthally changing phase delay to create a sound wave with helical phase fronts described by exp (il?). Such waves are predicted to have an orbital angular momentum to energy ratio of l/?s. We confirm this angular momentum content by measuring its transfer to a suspended 60 cm diameter acoustic absorbing tile. The resulting torque on the tile (?6.1x10-6 Nm) is measured from observation of the motion for various torsional pendulums. Furthermore, we confirm the helical nature of the acoustic beam by observing the rotational Doppler shift, which results from a rotation between source and observer of angular velocity ?r. We measure Doppler shifted frequencies of ?s±l?r depending on the direction of relative rotation

  20. An improved Doppler model for obtaining accurate maximum blood velocities.

    Science.gov (United States)

    Ricci, Stefano; Matera, Riccardo; Tortoli, Piero

    2014-09-01

    Maximum blood velocity estimates are frequently required in diagnostic applications, including carotid stenosis evaluation, arteriovenous fistula inspection, and maternal-fetal examinations. However, the currently used methods for ultrasound measurements are inaccurate and often rely on applying heuristic thresholds to a Doppler power spectrum. A new method that uses a mathematical model to predict the correct threshold that should be used for maximum velocity measurements has recently been introduced. Although it is a valuable and deterministic tool, this method is limited to parabolic flows insonated by uniform pressure fields. In this work, a more generalized technique that overcomes such limitations is presented. The new approach, which uses an extended Doppler spectrum model, has been implemented in an experimental set-up based on a linear array probe that transmits defocused steered waves. The improved model has been validated by Field II simulations and phantom experiments on tubes with diameters between 2mm and 8mm. Using the spectral threshold suggested by the new model significantly higher accuracy estimates of the peak velocity can be achieved than are now clinically attained, including for narrow beams and non-parabolic velocity profiles. In particular, an accuracy of +1.2±2.5 cm/s has been obtained in phantom measurements for velocities ranging from 20 to 80 cm/s. This result represents an improvement that can significantly affect the way maximum blood velocity is investigated today. PMID:24934798

  1. Observations of 2D Doppler backscattering on MAST

    CERN Document Server

    Thomas, D A; Freethy, S J; Huang, B K; Shevchenko, V F; Vann, R G L

    2015-01-01

    The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D Doppler backscattering (DBS) experiments on MAST. SAMI actively probes the plasma edge using a wide (+-40 degrees vertical and horizontal) and tuneable (10-35.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vivaldi PCB antennas. This allows the receiving array to be focused in any direction within the field of view simultaneously to an angular range of 6-24 degrees FWHM at 10-34.5 GHz. This capability is unique to SAMI and is an entirely novel way of conducting DBS experiments. In this paper the feasibility of conducting 2D DBS experiments is explored. Initial measurements of phenomena observed on conventional DBS experiments are presented; such as momentum injection from neutral beams and an abrupt change in power and turbulence velocity coinciding with the onset of H-mode. In addition, being able to carry out 2D DBS imaging allows a measurement of magnetic pitch an...

  2. On the Doppler effect for photons in rotating systems

    CERN Document Server

    Giuliani, Giuseppe

    2015-01-01

    The analysis of the Doppler effect for photons in rotating systems, studied using the M\\"ossbauer effect, confirms the general conclusions of a previous paper dedicated to experiments with photons emitted/absorbed by atoms/nuclei in inertial flight. The wave theory of light is so deeply rooted that it has been--and currently is--applied to describe phenomena in which the fundamental entities at work are discrete (photons). The fact that the wave theory of light can describe one aspect of these phenomena can not overshadow two issues: the corpuscular theory of light, firstly applied to the Doppler effect for photons by Schr\\"odinger in 1922, is by far more complete since it describes all the features of the studied phenomena; the wave theory can be used only when the number of photons at work is statistically significant. The disregard of basic methodological criteria may appear as a minor fault. However, the historical development of quantum physics shows that the predominance of the wave theory of radiation,...

  3. Magnetostriction measurement in thin films using laser Doppler vibrometry

    Energy Technology Data Exchange (ETDEWEB)

    Varghese, Ronnie, E-mail: ronniev@vt.edu [Center for Energy Harvesting Materials and Systems (CEHMS), Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, VA 24061 (United States); Viswan, Ravindranath [Materials Science and Engineering Department, Virginia Tech, Blacksburg, VA 24061 (United States); Joshi, Keyur [Center for Energy Harvesting Materials and Systems (CEHMS), Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, VA 24061 (United States); Seifikar, Safoura [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Zhou, Yuan [Center for Energy Harvesting Materials and Systems (CEHMS), Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, VA 24061 (United States); Schwartz, Justin [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Priya, Shashank [Center for Energy Harvesting Materials and Systems (CEHMS), Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, VA 24061 (United States)

    2014-08-01

    This paper reports the laser Doppler vibrometry based measurement of the magnetostriction in magnetic thin films. Using this method, the strain induced by an AC magnetic field in the polycrystalline cobalt ferrite and nickel ferrite thin films grown on silicon and platinized silicon substrates was measured under a DC magnetic bias. The experimental setup and the derivation of the magnetostriction constant from the experimentally measured deflection values are discussed. The magnetostriction values derived using force and bending moment balances were compared with that derived from an industry standard relationship. In addition, we corroborate our approach by comparing the values derived from bending theory calculations of magnetically induced torque to those from measurements using Vibrating Sample Magnetometer (VSM). At high DC magnetic field bias, the magnitude of magnetization calculated from the measured magnetostriction was found to match the measured magnetization by VSM. - Highlights: • Laser Doppler vibrometry based technique to measure magnetostriction in thin films. • Strain induced by an AC magnetic field under a DC magnetic bias. • Picometer level deflections in polycrystalline cobalt and nickel ferrite thin films.

  4. Evaluation of data obtained from atmospheric laser Doppler velocimeter

    Science.gov (United States)

    Keck, T. S.; Telford, J. W.

    1985-01-01

    The Doppler lidar velocimeter produces a variety of kinds of data. Besides the line of sight velocity components, there are the reflected amplitudes and the Doppler widths. Computer graphics software for displaying these data was produced. Different methods of presentation are needed for the various items. A picture was produced as pictures are often the best way to gain understanding. The individual lidar scans form a crosshatch pattern. Thus one-dimensional measurements fit together to form a two-dimensional whole. A pair of velocity measurements at a point combine to form a wind measurement with direction and magnitude. This gives a forest of wind vectors. The goal is to find a recognizable pattern to these trees. Often it is necessary to show only part of the information. That is, show only the wind direction not its magnitude or reduce the wind to streamlines of air flow. In other cases data are reduced to contour plots. Just enough contour lines are included to show the picture described.

  5. Magnetostriction measurement in thin films using laser Doppler vibrometry

    International Nuclear Information System (INIS)

    This paper reports the laser Doppler vibrometry based measurement of the magnetostriction in magnetic thin films. Using this method, the strain induced by an AC magnetic field in the polycrystalline cobalt ferrite and nickel ferrite thin films grown on silicon and platinized silicon substrates was measured under a DC magnetic bias. The experimental setup and the derivation of the magnetostriction constant from the experimentally measured deflection values are discussed. The magnetostriction values derived using force and bending moment balances were compared with that derived from an industry standard relationship. In addition, we corroborate our approach by comparing the values derived from bending theory calculations of magnetically induced torque to those from measurements using Vibrating Sample Magnetometer (VSM). At high DC magnetic field bias, the magnitude of magnetization calculated from the measured magnetostriction was found to match the measured magnetization by VSM. - Highlights: • Laser Doppler vibrometry based technique to measure magnetostriction in thin films. • Strain induced by an AC magnetic field under a DC magnetic bias. • Picometer level deflections in polycrystalline cobalt and nickel ferrite thin films

  6. On-The-Fly neutron Doppler broadening in MCNP

    International Nuclear Information System (INIS)

    Multi-physics calculations may involve coupling continuous-energy Monte Carlo neutronics codes to CFD codes that provide many thousands or even millions of region temperatures. The traditional Monte Carlo approach - using pre-calculated Doppler broadened nuclear cross-sections - is not feasible for these large multi-physics problems. Instead, an On-the-Fly (OTF) Doppler broadening methodology is required, whereby neutron cross-sections are broadened during the Monte Carlo transport. To this end, we have developed a methodology for MCNP to provide OTF broadening based on cell temperatures during neutron tracking. The method enables the use of many thousands or more temperatures in MCNP Monte Carlo calculations for multi-physics applications, significantly advancing the state-of-the-art by permitting the solution of problems that were not previously possible with continuous-energy Monte Carlo codes. A production library with an extended set of isotopes has been developed for use with MCNP6. Calculations of test problems with MCNP6 and the new library demonstrate the accuracy and effectiveness of the OTF approach. (authors)

  7. Method for ambiguity resolution in range-Doppler measurements

    Science.gov (United States)

    Heymsfield, Gerald M. (inventor); Miller, Lee S. (inventor)

    1994-01-01

    A method for resolving range and Doppler target ambiguities when the target has substantial range or has a high relative velocity in which a first signal is generated and a second signal is also generated which is coherent with the first signal but at a slightly different frequency such that there exists a difference in frequency between these two signals of Delta f(sub t). The first and second signals are converted into a dual-frequency pulsed signal, amplified, and the dual-frequency pulsed signal is transmitted towards a target. A reflected dual-frequency signal is received from the target, amplified, and changed to an intermediate dual-frequency signal. The intermediate dual-frequency signal is amplified, with extracting of a shifted difference frequency Delta f(sub r) from the amplified intermediate dual-frequency signal done by a nonlinear detector. The final step is generating two quadrature signals from the difference frequency Delta f(sub t) and the shifted difference frequency Delta f(sub r) and processing the two quadrature signals to determine range and Doppler information of the target.

  8. Doppler disc tomography applied to low mass AGN spin

    CERN Document Server

    Middleton, Matthew

    2014-01-01

    Doppler tomography can provide a powerful means of determining black hole spin when our view to the central regions are revealed and obscured by optically thick orbiting material, and can provide an independent estimate that does not suffer as many degeneracies as traditional methods. For low mass AGN, time-dependent obscuration is expected to leave a signature in the changing spectrum of the disc emission which extends into the soft X-ray bandpass. We create a spectral model incorporating Doppler tomography and apply it to the case of the low mass (8$\\times$10$^{5}$ M$_{\\odot}$) AGN, RX J1301.9+2747 which shows unusual timing properties in the form of short-lived flares that we argue are best explained by the orbit of a window through an optically thick wind. Modelling the phase-resolved spectrum over the course of the highest data quality flare indicates a very low spin even when we relax our constraints. This is the lowest mass AGN for which a spin has been measured and the first via this technique. We not...

  9. Blood velocity estimation by Doppler ultrasound: Problems and issues

    Science.gov (United States)

    Cobbold, Richard S. C.; Steinman, Aaron H.

    2002-05-01

    Modern methods of estimating blood flow have advanced considerably since Dr. Satamura and his colleagues at Osaka University reported the first measurements in 1959 using CW ultrasound. Most current methods involve the use of linear or phased arrays, which make possible 2-D color flow mapping, measurements from a single sample volume, and simultaneous B-mode imaging. However, along with this technology, troubling reports have been published (including our own) concerning the accuracy with which the velocity can be estimated and this has serious potential consequences in the quantitative assessment of vascular disease. The cause has not yet been completely identified, but appears to be partially associated with the wide range of Doppler angles within the sample volume, the complexity of the ultrasound propagation process, and the stochastic nature of the red blood cells flowing in the blood vessels. These causes will provide a focus for our review of the current status of Doppler ultrasound for vascular disease assessment and suggestions for future research. Specifically, a complete model of the entire measurement system is needed, and this includes the beamforming architecture, signal processing, possible nonlinear effects, scattering process, and nature of the 3-D vector flow field being measured.

  10. On-The-Fly Neutron Doppler Broadening in MCNP

    Science.gov (United States)

    Martin, William R.; Brown, Forrest B.; Wilderman, Scott; Yesilyurt, Gokhan

    2014-06-01

    Multi-physics calculations may involve coupling continuous-energy Monte Carlo neutronics codes to CFD codes that provide many thousands or even millions of region temperatures. The traditional Monte Carlo approach - using precalculated Doppler broadened nuclear cross-sections - is not feasible for these large multiphysics problems. Instead, an On-the-Fly (OTF) Doppler broadening methodology is required, whereby neutron cross-sections are broadened during the Monte Carlo transport. To this end, we have developed a methodology for MCNP to provide OTF broadening based on cell temperatures during neutron tracking. The method enables the use of many thousands or more temperatures in MCNP Monte Carlo calculations for multiphysics applications, significantly advancing the state-of-the-art by permitting the solution of problems that were not previously possible with continuous-energy Monte Carlo codes. A production library with an extended set of isotopes has been developed for use with MCNP6. Calculations of test problems with MCNP6 and the new library demonstrate the accuracy and effectiveness of the OTF approach.

  11. Development of coherent Doppler lidar for wind profiling

    Science.gov (United States)

    Mizutani, Kohei; Itabe, Toshikazu; Ishii, Shoken; Aoki, Tetsuo; Sasano, Masahiko; Asai, Kazuhiro; Sato, Atsushi

    2005-01-01

    Space-borne Doppler lidar is expected to make wind profile observations on a global scale with an accuracy of 1 to 2 m/s. It may solve the problem of the shortage of the accuracy and distribution in the current wind data. We have studied an eye-safe coherent Doppler lidar (CDL) model that could be deployed on the exposed facilities of Japanese Experiment Module (JEM) and that would meet the science requirements. We have good prospects of 500mJ output at 10Hz in a conduction cooling sub-scale laser, which could be a small model of space-borne laser for JEM/CDL. We are making studies on improving the system"s efficiency, reducing its weight, and establishing the fundamental technologies involved. Research on another possibility, e.g. a free flyer, for a demonstration mission besides of JEM/CDL is also valuable to be considered. Development of algorithm for application of coherent lidar system is also in progress through air-borne experiments and ground-based observations.

  12. On the Doppler effect for photons in rotating systems

    International Nuclear Information System (INIS)

    The analysis of the Doppler effect for photons in rotating systems, studied using the Mössbauer effect, confirms the general conclusions of a previous paper dedicated to experiments with photons emitted/absorbed by atoms/nuclei in inertial flight. The wave theory of light is so deeply rooted that it continues to be applied to describe phenomena in which the fundamental entities at work are discrete (photons). The fact that the wave theory of light can describe one aspect of these phenomena should not overshadow two issues: the corpuscular theory of light, first applied to the Doppler effect for photons by Schrödinger in 1922, is by far more complete since it describes all of the features of the studied phenomena; the wave theory can only be used when the number of photons at work is statistically significant. This disregarding of basic methodological criteria may appear to be a minor fault. However, the historical development of quantum physics shows that the predominance of the wave theory of radiation, beyond its natural application domain, has hampered the reorientation toward the photon description of the underlying phenomena. (paper)

  13. Design, Assembly, and Testing of a Photon Doppler Velocimetry Probe

    International Nuclear Information System (INIS)

    A novel fiber-optic probe measures the velocity distribution of an imploding surface along many lines of sight. Reflected light from each spot on the moving surface is Doppler shifted with a small portion of this light propagating backwards through the launching fiber. The reflected light is mixed with a reference laser in a technique called photon Doppler velocimetry, providing continuous time records. Within the probe, a matrix array of 56 single-mode fibers sends light through an optical relay consisting of three types of lenses. Seven sets of these relay lenses are grouped into a close-packed array allowing the interrogation of seven regions of interest. A six-faceted prism with a hole drilled into its center directs the light beams to the different regions. Several types of relay lens systems have been evaluated, including doublets and molded aspheric singlets. The optical design minimizes beam diameters and also provides excellent imaging capabilities. One of the fiber matrix arrays can be replaced by an imaging coherent bundle. This close-packed array of seven relay systems provides up to 476 beam trajectories. The pyramid prism has its six facets polished at two different angles that will vary the density of surface point coverage. Fibers in the matrix arrays are angle polished at 8o to minimize back reflections. This causes the minimum beam waist to vary along different trajectories. Precision metrology on the direction cosine trajectories is measuthe direction cosine trajectories is measured to satisfy environmental requirements for vibration and temperature.

  14. Doppler broadening of position annihilation photos in uranium

    International Nuclear Information System (INIS)

    The annihilation positron characteristics in metallic uranium is investigated with respect to the lattice structure and the crystal defects. Measurements of Doppler broadening annihilation photons are carried out as a function of quenching temperatures between 20 deg C and 1030 deg C by a lithium-drifted germanium detector with an energy resolution of 1.4 keV at the 514 keV gamma line of 85Sr in coincidence with a NaI(Tl)-scintillation detector. The analyses of the experimental data are based on the two-state trapping model. In order to take into account the contributions of the 238U-and 235U-exited daughter products to the measured 511 keV annihilation line the isotope concentrations in the uranium samples are determined by a gamma spectoscopy me--thod. The Doppler broadening line shape parameter and the intensity of the parabolic component of the annihilation spectrum are given as a function of temperature. The parameters increase strongly in four temperature ranges: (1) at about 330 deg C, which is connected with the redistribution of the outer shell valence electrons; (2) in the ranges corresponding to the ?-?(about 670 deg C) and ??? (about 780 deg C) phase transitions; (3) at temperatures higher than 780 deg C. It is shown that in the last temperature range the defect concentration increase non-linearly and point and linear-type defects are formed in the quenching uranium sample

  15. Doppler lidar observations of plume dynamics from large wildfires

    Science.gov (United States)

    Lareau, N.; Clements, C. B.

    2014-12-01

    Novel Doppler lidar observations of smoke plumes from large wildfires are made from a mobile atmospheric profiling system. Few quantitative observations exist that resolve the plume dynamics of active wildfires. Our observations elucidate three important and poorly understood aspects of convective columns: (1) column rotation, (2) penetrative convection, and (3) deep pyrocumulus clouds. Our first observational case examines vigorus anti-cyclonic rotation that occurred in a rapidly developing wildfire. The convective column was first purely convergent, then as the fire intensified, the column acquired strong (+/- 15 m s-1) anticyclonic rotation. The Doppler lidar recorded the vortex structure, strength, and evolution, including the merger of smaller vorticies into a single long-lived vortex. The second case examines the interaction of the convective plumes with shear layers and capping stable layers. These data show explosive convective growth as fire-induced buoyancy penetrated into the free troposphere. Observations of entrainment into the plumes is expecitly resolved in the lidar scans. The final case examines rarely observed deep pyrocumulus clouds associated with an intense forest fire. The lidar data reveal plume structure, including t the height of the lifted condensation level and the full height of the plume top which was in excess of 8 km AGL.

  16. Raman processes in sub-Doppler laser cooling

    International Nuclear Information System (INIS)

    We have observed a new type of sub-Doppler laser cooling with neither polarization gradients nor magnetic fields. All known sub-Doppler laser cooling methods require one of these two to resdistribute the atomic population among the energy levels. This allows the irreversible processes of optical pumping vels. This allows the irreversible processes of optical pumping (OP) to manipulate the conservative force of light shifts (e.g. resonant exchange between the two beams comprising a standing wave) into a damping force. Our scheme employs stimulated Raman transitions between ground state hyperfine levels of Rb with a bichromatic standing wave, accompanied by a momentum change of ?p = 2?k. OP, with ?p = 1?k, creates a population imbalance allowing repetition of the Raman process. When the detuning of the light from Raman resonance ? is properly chosen, the net momentum exchange damps the atomic motion. Changing ? by only ?/6(1 MHz) replaces cooling by heating. This process separates the velocity selective Raman resonance and OP processes differently from others, and helps clarify the role of these different mechanisms

  17. Utilización de la flujometría Doppler en el manejo de la restricción del crecimiento pretérmino / Using Doppler flowmetry in the preterm growth restriction management

    Scientific Electronic Library Online (English)

    Alfredo, Nodarse Rodríguez; Ana Mary, Sanabria Arias; Lourdes, Carrillo Bermúdez; Niobys Maya, Sánchez Ramírez; Irina, Soler Guibert; Roberto, Guzmán Parrado.

    2013-03-01

    Full Text Available Introducción: el Doppler umbilical es una herramienta fundamental en el diagnóstico de la restricción del crecimiento fetal que permite clasificar los riesgos de morbimortalidad y contribuye a estratificar el nivel de control obstétrico necesario en los fetos con alteraciones biométricas. Objetivo: [...] describir los resultados perinatales en recién nacidos pretérmino con crecimiento intrauterino restringido. Métodos: el universo del presente estudio estuvo constituido por 585 nacidos vivos pretérmino en el Hospital Ginecobstétrico Docente "Ramón González Coro" de La Habana entre el 1ro. de julio de 2008 y el 30 junio de 2011, a los que se le realizó flujometría Doppler ante el diagnóstico de bajo peso o restricción del crecimiento fetal. Resultados: el ANOVA realizado mostró que no hubo asociación significativa del Doppler con la edad gestacional al nacimiento y el peso al nacer, p= 0,675, p= 0,714, respectivamente, pero sí con los días transcurridos entre los resultados del Doppler y la interrupción de la gestación. Según la prueba X2= 23,796; gl= 6 y p Abstract in english Introduction: umbilical Doppler is a fundamental tool in the diagnosis of fetal growth restriction for classifying morbidity and mortality risks and it contributes to stratify the necessary control level of obstetrical in fetuses with biometric abnormalities. Objective: to describe the perinatal out [...] come in preterm infants with restricted intrauterine growth. Method: 585 preterm births was the universe of this study at Ramón González Coro Teaching Hospital in Havana from July 1st, 2008 to June 30th, 2011, who underwent Doppler flowmetry before the diagnosis of low birth weight or fetal growth restriction. Results: no significant association with Doppler gestational age at birth (p= 0.675) and birth weight (p= 0.714) was shown when ANOVA was performed; but there was association with the days elapsed between the Doppler results and interruption of gestation. According to the test (X2= 23.796, df= 6 and p

  18. Doppler effects in a left-handed material: a first-principle theoretical study

    OpenAIRE

    Xiao, Sanshui; Qiu, Min

    2004-01-01

    The Doppler effects for the reflected wave from a moving media are systemically analyzed in this paper. The theoretical formula for the Doppler shift in the left-handed material, which is described by Drude's dispersion model, is presented. This formula is examined by first-principles numerical experiments, which are in agreement with the theoretical results.

  19. Strain rate derived from color Doppler myocardial imaging for assessment of fetal cardiac function

    DEFF Research Database (Denmark)

    Larsen, L U; Petersen, O B

    2006-01-01

    Color Doppler myocardial imaging (CDMI) is a new multigated method that allows direct analysis of myocardial motion. It is superior to pulsed-wave tissue Doppler in its ability to generate new and important indices of myocardial function such as strain, strain rate and tissue tracking. The purpose of this study was to assess the feasibility of CDMI in the fetal heart.

  20. Speed distributions of the photofragments of vinyl chloride determined by direct inversion of Doppler profiles

    Science.gov (United States)

    Huang, Yibo; He, Guoxin; Yang, Yungan; Hashimoto, Satoshi; Gordon, Robert J.

    1994-11-01

    A method is developed for extracting the photofragment speed distribution function from a velocity aligned Doppler spectrum. This method is used to determine the distribution function of HCl produced by 193 nm photodissociation of vinyl chloride. The speed distribution of the Cl fragment is determined by the method of magic angle Doppler spectroscopy.

  1. Operator Auditory Perception and Spectral Quantification of Umbilical Artery Doppler Ultrasound Signals

    OpenAIRE

    Thuring, Ann; Bra?nnstro?m, Jonas; Ewerlo?f, Maria; Hernandez-andrade, Edgar; Ley, David; Lingman, Go?ran; Liuba, Karina; Marsal, Karel; Jansson, Tomas

    2013-01-01

    An experienced sonographer can by listening to the Doppler audio signals perceive various timbres that distinguish different types of umbilical artery flow despite an unchanged pulsatility index (PI). Our aim was to develop an objective measure of the Doppler audio signals recorded from fetoplacental circulation in a sheep model.

  2. Differentiation of Benign and Malignant Skin Lesions with Color and Power Doppler Ultrasonography

    OpenAIRE

    Bülent Petik

    2013-01-01

          Aim: The aim of this study was to prospectively evaluate the usefulness of color Doppler ultrasonography, power Doppler ultrasonography, and gray scale ultrasonography in differentiating benign and malignant skin lesions. Material and Method: Patients were histopathologically divided into two groups as benign and malignant skin tumors. The dimensions of the lesion, the contour characteristics, existence of pagoda echo, levels of invasion, the internal echogenici...

  3. Laser Doppler anemometer: new algorithm for signal processing at high light scattering

    Science.gov (United States)

    Borozdova, M. A.; Fedosov, I. V.; Tuchin, V. V.

    2015-03-01

    We developed a Laser Doppler anemometer which uses a novel technique of signal processing to minimize the effect of undesirable light scattering. The technique has been applied to estimate Doppler frequency shift at flow velocity measurements. We have shown that technique is applicable for measurements in turbid media like biological tissues.

  4. Measurement of high intensity atomic and ionic beams by using method of Doppler laser spectroscopy

    International Nuclear Information System (INIS)

    The possibility of measuring divergence of high intensity atomic and ionic beams by using the method of Doppler laser spectroscopy, proposed by the author, is considered. This method, which is based on the detection of induced atomic radiation, allows for increased efficiency of detecting primary levels in comparison with passive Doppler spectroscopy which uses detection of spontaneous radiation

  5. Frequency-domain, wide-field laser Doppler in vivo imaging

    OpenAIRE

    Atlan, Michael; Gross, Michel; Forget, Benoit,; Vitalis, Tania; Rancillac, Armelle; Dunn, Andrew

    2006-01-01

    We present a new instrument, based on a low frame rate (8 Hz) CCD camera used in a heterodyne optical-mixing configuration, that can create wide-field laser Doppler maps. As an illustration, we show results obtained in a mouse brain, in vivo, showing the Doppler signature of blood flow. The instrument is based on the frequency-shifting digital holography scheme.

  6. Evaluation of gastrointestinal activity patterns in healthy horses using B mode and Doppler ultrasonography

    OpenAIRE

    Mitchell, Colin F.; Malone, Erin D.; Sage, Abby M.; Niksich, Katie

    2005-01-01

    Healthy adult horses were examined by using transabdominal ultrasonography to quantitatively and qualitatively evaluate activity of the jejunum, cecum, and colon with B mode and Doppler techniques. Doppler ultrasound was used to assess jejunal peristaltic activity. Examinations were performed on multiple occasions under imposed colic evaluation conditions, including fasting, nasogastric intubation, and xylazine sedation.

  7. Effect of interposed skin at Doppler flow estimation at 5 and 10 MHz

    International Nuclear Information System (INIS)

    Flow measurements with high ultrasound frequencies (Doppler technique) can be used at quantitative estimations of flow. A calibrator for Doppler equipments is presented. The effect of skin as interposed material with 10 MHz and 5 MHz is discussed as are limitations in the apparatus itself especially when using 10 MHz ultrasound. (Auth.)

  8. Doppler Reactivity Feedback Model for Metal-fueled Liquid Metal Reactors

    International Nuclear Information System (INIS)

    In fast reactors, the Doppler effect is the completely reliable, prompt, negative reactivity feedback mechanism. A prompt negative reactivity feedback is particularly important for fast reactors because of a possibility of fuel compaction and sodium loss. The fuel compaction under a sodium loss condition has the potential to make the reactor super prompt critical. The Doppler effect provides a prompt negative reactivity feedback and can help limit the extent of a power-increase excursion if the reactor becomes prompt critical. The Doppler effect is the direct result of the laws of nature. As the fuel temperature rises, the increased kinetic motion of the fuel atoms results in the broadening of cross-section resonances and increasing resonance absorption. This has the effect of removing active neutrons from the core and reducing the reactivity. Doppler feedback is the fastest acting feedback mechanism. KALIMER-600 has a metal fueled core. Metal-fueled reactors have a hard neutron spectrum because they have no moderator in the fuel matrix. The flux in the principal Doppler resonance region for the metal-fueled reactors is less than that for the oxide-fueled reactors. Two analytical methods are suggested in this report as a prediction method of Doppler feedback effect in fast reactor transients with a metal fueled core. The first method is to use the temperature correlation representing the whole core Doppler coefficient. The second one is to follow the calculation way for the mixed-oxide fuel with the Doppler constants calculated for metal fueled core

  9. Device for stabilization of middle position of Moessbauer Doppler modulator source

    International Nuclear Information System (INIS)

    A device for stabilization of middle position of Moessbauer spectrometer Doppler modulator rod is described. The device contains induction type displacement gage and a circuit which produces a signal of Doppler modulator mobile part deviation from the middle position. Utilization of this device with a unified spectrometer YaGRS-4M completely eliminated instrumental errors resulting from imperfection of spectrometer stabilization system

  10. Algunas aplicaciones del Doppler transcraneal no habituales en las unidades de cuidados intensivos Some uncommon applications of transcranial Doppler in the intensive care unit

    Directory of Open Access Journals (Sweden)

    J.A. Álvarez-Fernández

    2009-03-01

    Full Text Available Se presenta el caso de una mujer de 64 años con shock por colitis isquémica en relación con embolia paradójica a través de un foramen oval permeable. Se comentan algunas utilidades del Doppler transcraneal empleadas en este caso que podrían tener interés habitual en cuidados intensivos e intermedios. Éstas incluyen el análisis de la distribución regional del flujo sanguíneo cerebral, la monitorización arterial intracraneal para detección de microembolias espontáneas o la inyección de microburbujas para detección de cortocircuito derecha-izquierda. Se destaca el valor añadido aportado por la incorporación del Doppler modo M a la ultrasonografía Doppler transcraneal.We present the case of a 64-year old woman with shock related to ischemic colitis associated with paradoxical embolism through a foramen ovale. Some utilities of transcranial Doppler ultra-sonography applied in this case that could have an usual interest in intensive and intermediate care are discussed. These include analysis of the regional distribution of cerebral blood flow, intracranial arterial continuous monitoring for detection of spontaneous microembolisms and injection of microbubbles to detect right to left shunts. The added value of using power M-mode Doppler in transcranial Doppler evaluations is highlighted.

  11. Algunas aplicaciones del Doppler transcraneal no habituales en las unidades de cuidados intensivos / Some uncommon applications of transcranial Doppler in the intensive care unit

    Scientific Electronic Library Online (English)

    J.A., Álvarez-Fernández; R., Pérez-Quintero.

    2009-03-01

    Full Text Available Se presenta el caso de una mujer de 64 años con shock por colitis isquémica en relación con embolia paradójica a través de un foramen oval permeable. Se comentan algunas utilidades del Doppler transcraneal empleadas en este caso que podrían tener interés habitual en cuidados intensivos e intermedios [...] . Éstas incluyen el análisis de la distribución regional del flujo sanguíneo cerebral, la monitorización arterial intracraneal para detección de microembolias espontáneas o la inyección de microburbujas para detección de cortocircuito derecha-izquierda. Se destaca el valor añadido aportado por la incorporación del Doppler modo M a la ultrasonografía Doppler transcraneal. Abstract in english We present the case of a 64-year old woman with shock related to ischemic colitis associated with paradoxical embolism through a foramen ovale. Some utilities of transcranial Doppler ultra-sonography applied in this case that could have an usual interest in intensive and intermediate care are discus [...] sed. These include analysis of the regional distribution of cerebral blood flow, intracranial arterial continuous monitoring for detection of spontaneous microembolisms and injection of microbubbles to detect right to left shunts. The added value of using power M-mode Doppler in transcranial Doppler evaluations is highlighted.

  12. Stokes $IQUV$ Magnetic Doppler Imaging of Ap stars II: Next Generation Magnetic Doppler Imaging of $\\alpha^2$ CVn

    CERN Document Server

    Silvester, J; Wade, G A

    2014-01-01

    We present updated magnetic field maps of the chemically peculiar B9p star $\\alpha^2$ CVn created using a series of time resolved observations obtained using the high resolution spectropolarimeters ESPaDOnS and Narval. We compare these new magnetic field maps with the original magnetic Doppler imaging maps based on spectra recorded with the MuSiCoS spectropolarimeter and taken a decade earlier. These new maps are inferred from line profiles in all four Stokes parameters using the magnetic Doppler imaging code INVERS10. With the addition of new lines exhibiting Stokes $IQUV$ signatures we have a unique insight into how the derived magnetic surface structure may be affected by the atomic lines chosen for inversion. We report new magnetic maps of $\\alpha^2$ CVn created using strong iron lines (directly comparable to the published MuSiCoS maps), weak iron lines and chromium lines, all of which yield a magnetic field structure roughly consistent with that obtained previously. We then derive an updated magnetic str...

  13. Valor diagnóstico de la ecografía Doppler transcraneal en oftalmología / Diagnostic value of transcranial Doppler ultrasound in ophthalmology

    Scientific Electronic Library Online (English)

    Mayelín, Navarro Scott; Alina, Recasens Cáceres; Ana, Lamas Ávila.

    2011-04-01

    Full Text Available La ecografía Doppler transcraneal oftálmica es el estudio no invasivo de los vasos oculares intracraneales, útil no solo como prueba de exploración selectiva, sino también como instrumento para valorar la extensión y gravedad de las enfermedades arteriales. Sus usos en el campo oftalmológico son múl [...] tiples, aunque en la mayoría de los casos se indica para precisar los cambios del flujo sanguíneo en pacientes diabéticos, con retinopatía o sin ella. Dada la importancia que en los últimos años han ido adquiriendo las alteraciones vasculares en la génesis de algunas afecciones oculares, particularmente en el glaucoma, se decidió revisar la bibliografía médica sobre esa técnica de ultrasonidos para destacar su valor radiodiagnóstico en oftalmología. Abstract in english Transcranial Doppler ultrasound in ophthalmology is a noninvasive study of intracranial ocular vessels, useful not only as a selective scanning test, but also as a tool to evaluate the extent and severity of arterial disease. Its uses in ophthalmology are numerous, although in most cases it is indic [...] ated to specify the changes of the blood flow in diabetic patients with retinopathy o without it. Given the importance that in recent years vascular abnormalities have acquired in the genesis of some ocular conditions, particularly in glaucoma, it is decided to review the literature on that ultrasonic technique to highlight its radiodiagnostic value in ophthalmology.

  14. Valor diagnóstico de la ecografía Doppler transcraneal en oftalmología Diagnostic value of transcranial Doppler ultrasound in ophthalmology

    Directory of Open Access Journals (Sweden)

    Mayelín Navarro Scott

    2011-04-01

    Full Text Available La ecografía Doppler transcraneal oftálmica es el estudio no invasivo de los vasos oculares intracraneales, útil no solo como prueba de exploración selectiva, sino también como instrumento para valorar la extensión y gravedad de las enfermedades arteriales. Sus usos en el campo oftalmológico son múltiples, aunque en la mayoría de los casos se indica para precisar los cambios del flujo sanguíneo en pacientes diabéticos, con retinopatía o sin ella. Dada la importancia que en los últimos años han ido adquiriendo las alteraciones vasculares en la génesis de algunas afecciones oculares, particularmente en el glaucoma, se decidió revisar la bibliografía médica sobre esa técnica de ultrasonidos para destacar su valor radiodiagnóstico en oftalmología.Transcranial Doppler ultrasound in ophthalmology is a noninvasive study of intracranial ocular vessels, useful not only as a selective scanning test, but also as a tool to evaluate the extent and severity of arterial disease. Its uses in ophthalmology are numerous, although in most cases it is indicated to specify the changes of the blood flow in diabetic patients with retinopathy o without it. Given the importance that in recent years vascular abnormalities have acquired in the genesis of some ocular conditions, particularly in glaucoma, it is decided to review the literature on that ultrasonic technique to highlight its radiodiagnostic value in ophthalmology.

  15. Structure of a swirl-stabilized spray flame by imaging, laser Doppler velocimetry, and phase Doppler anemometry

    Science.gov (United States)

    Edwards, C. F.; Rudoff, R. C.

    1991-01-01

    Data are presented which describe the mean structure of a steady, swirl-stabilized, kerosene spray flame in the near-injector region of a research furnace. The data presented include ensemble-averaged results of schlieren, luminosity, and extinction imaging, measurement of the gas phase velocity field by laser Doppler velocimetry, and characterization of the condensed phase velocity by phase Doppler anemometry. The results of these studies define six key regions in the flame: the dense spray region; the rich, two-phase, fuel jet; the main air jet; the internal product recirculation zone; the external product recirculation zone; and the gaseous diffusion flame zone. The first five of these regions form a conical mixing layer which prepares the air and fuel for combustion. The air and fuel jets comprise the central portion of this mixing layer and are bounded on either side by the hot product gases of the internal and external recirculation zones. Entrainment of these product gases into the air/fuel streams provides the energy required to evaporate the fuel spray and initiate combustion. Intermittency of the internal recirculation and spray jet flows accounts for unexpected behavior observed in the aerodynamics of the two phases. The data reported herein are part of the database being accumulated on this spray flame for the purpose of detailed comparison with numerical modeling.

  16. An Performance Study for Sectorised Antenna based Doppler Diversity in High-Speed Railway Communications

    Directory of Open Access Journals (Sweden)

    Cheng Tao

    2011-12-01

    Full Text Available The wireless channel of High-Speed Railway communication system is rapidly time-varying. The orthogonal frequency division multiplexing transmitting over this channel will be exposed to the intercarrier interference caused by large Doppler spread. The sectorised antenna can be employed for Doppler mitigation and obtaining Doppler diversity gain. In this paper the performance of this directional antenna is analyzed. The preferable partition scheme for the omnidirectional antenna and the optimal Doppler compensation frequency are addressed firstly. And the uncorrelated property of the signal received from the different sectorised antennas is demonstrated originally which can be utilized for Doppler diversity gain. Finally, it is proved by the simulation results that this architecture will allows us to achieve remarkable performance under high mobility conditions.

  17. Terrestrial--Doppler Adjustment and Analysis of the Primary Triangulation of Great Britain: Preliminary Report

    Science.gov (United States)

    Ashkenazi, V.; Crane, S. A.; Williams, J. W.; Dean, J. D. A.

    1980-01-01

    The 1977 readjustment of the primary triangulation of Great Britain resulted in an internally consistent geodetic framework. The remaining suspected sources of systematic error could only be detected through comparisons with satellite Doppler derived observations carried out at selected stations of the network. These comparisons are followed by a simultaneous adjustment and strength analysis involving both terrestrial observations and Doppler positional data. The results of this combined adjustment are compared with the 1977 coordinates to assess the contribution of the satellite Doppler-derived data. Details are given of the choice of the reference system, the treatment of the Doppler data and the assignment of a priori standard errors of the various types of observations. The variance--covariance analysis is carried out with real data as well as with simulated observations in order to quantify the contribution of additional satellite Doppler observations to the geometrical strength of the combined network.

  18. Strain-rate sensor based on in-fiber Doppler velocimetry

    Science.gov (United States)

    Lo, Yu Lung; Sirkis, James S.

    1998-05-01

    An optical fiber strain-rate sensor based on in-line Doppler velocimetry is developed using a 3 X 3 coupler with a large path imbalance Mach-Zehnder interferometer for passive demodulation of Doppler wavelength shifts. A model is developed that relates the strain rate in an optical fiber to the corresponding Doppler wavelength shifts. The strain rate obtained by differentiating strain from a Michelson strain sensor mounted on the piezoelectric transistor cylinder shows good agreement with the strain rate directly obtained from the Doppler-based strain-rate sensor. The Doppler-based strain-rate sensor is also bonded to a Hopkinson pressure bar in an attempt to detect the stress waves propagation. It is shown that the higher the strain rate of stress wave, the easier it is to couple into the lead in/out fiber.

  19. Korea-China Joint R and D on Doppler Lidar Technology

    International Nuclear Information System (INIS)

    Doppler lidar technology is to monitor atmospheric wind velocity by measuring the light scattering signals between a laser and aerosol particles or molecules existing in the atmosphere. When the particles (or molecules) in the atmosphere are moving by wind force, the frequency of backscattering light is shifted by doppler effect, so that the wind velocity profile can be obtained by measurement of the shifted frequencies. When the laser radiation is scanned in four different direction, three dimensional wind profiles are obtained. The Anhui Institute of Optics and Fine Mechanics under the China Academy of Sciences has developed and operated the doppler lidar system for long time. In this project we want to developed a new technologies adopted to the chinese doppler system and to test the updated In the process of collaboration between China and Korea research teams, we want to learn the state-of-art technology involved in the doppler lidar system

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

    CERN Document Server

    Kopeikin, S M

    1999-01-01

    The determination of velocities of stars from precise Doppler measurements is described here using relativistic theory of astronomical reference frames so as to determine the Keplerian and post-Keplerian parameters of binary systems. Seven appropriate reference frames are introduced and then we apply successive Lorentz transformations and the relativistic equation of light propagation to establish the exact treatment of Doppler effect in binary systems, both in special and general relativity theories. As a result, the Doppler shift is a sum of (1) linear in $c^{-1}$ terms, which include the ordinary Doppler effect and its variation due to the secular radial acceleration of the binary with respect to observer; (2) terms proportional to $c^{-2}$, which include the contributions from the quadratic Doppler effect caused by the relative motion of binary star with respect to the Solar system, motion of the particle emitting light and diurnal rotational motion of observer, orbital motion of the star around the binar...