WorldWideScience
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)

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

Scientific Electronic Library Online (English)

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

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

2004-08-01

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

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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

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

Directory of Open Access Journals (Sweden)

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

Silvio Henrique Barberato

2006-06-01

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

Scientific Electronic Library Online (English)

Full Text Available OBJETIVO: Avaliar os efeitos da redução da pré-carga induzida por uma sessão de hemodiálise sobre o índice de desempenho miocárdico (Tei) e outros parâmetros ecocardiográficos de função cardíaca. MÉTODOS: Estimamos o índice de Tei e parâmetros de função sistólica e diastólica do ventrículo esquerdo [...] (VE), antes e depois de uma sessão de hemodiálise. Incluímos no estudo indivíduos em ritmo sinusal e sem antecedentes de insuficiência coronariana ou evidências de valvopatia e derrame pericárdico. RESULTADOS: 15 pacientes (8 homens, idade 53 ± 14 anos) completaram o estudo. Após ultrafiltração de 2,2 ± 1,1 litros, a onda E diminuiu (p Abstract in english OBJECTIVE: To assess the influence of preload reduction by hemodialysis on Doppler Tei Index of myocardial performance and other parameters of cardiac function. METHODS: The Tei index and left ventricular (LV) systolic and diastolic function parameters were estimated, before and after a single hemod [...] ialysis session. Only subjects who were in sinus rhythm, without history of coronary artery disease, and no evidence of cardiac valve disease and pericardial effusion were included in the study. RESULTS: Fifteen patients (8 men, mean age 53 ± 14 years) completed the study. After an ultrafiltration of 2,2 ± 1,1 liters, peak mitral E velocity decreased (p

Silvio Henrique, Barberato; Roberto, Pecoits Filho.

2006-06-01

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

Scientific Electronic Library Online (English)

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

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

2010-06-01

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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)

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.

Sava? Özsu

2012-12-01

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Position Estimation Using Image Derivative  

Science.gov (United States)

This paper describes an image processing algorithm to process Moon and/or Earth images. The theory presented is based on the fact that Moon hard edge points are characterized by the highest values of the image derivative. Outliers are eliminated by two sequential filters. Moon center and radius are then estimated by nonlinear least-squares using circular sigmoid functions. The proposed image processing has been applied and validated using real and synthetic Moon images.

Mortari, Daniele; deDilectis, Francesco; Zanetti, Renato

2015-01-01

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Using TEI, CMDI and ISOcat in CLARIN-DK  

DEFF Research Database (Denmark)

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.

Hansen, Dorte Haltrup; Offersgaard, Lene

2014-01-01

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

Science.gov (United States)

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

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

2014-11-01

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Doppler Effect  

Science.gov (United States)

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

Mrs. Brown

2010-10-26

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Doppler Tomography  

OpenAIRE

I review the method of Doppler tomography which translates binary-star line profiles taken at a series of orbital phases into a distribution of emission over the binary. I begin with a discussion of the basic principles behind Doppler tomography, including a comparison of the relative merits of maximum entropy regularisation versus filtered back-projection for implementing the inversion. Following this I discuss the issue of noise in Doppler images and possible methods for c...

Marsh Tom

2000-01-01

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Crystal structure of human cyclin-dependent kinase-2 complex with MK2 inhibitor TEI-I01800: insight into the selectivity  

OpenAIRE

The Gly-rich loop of cyclin-dependent kinase 2 (CDK2) bound to TEI-I01800 as an MK2 specific inhibitor forms a ?-sheet which is a common structure in CDK2–ligand complexes. Here, the reason why TEI-I01800 does not become a strong inhibitor against CDK2 based on the conformation of TEI-I01800 is presented.

Fujino, Aiko; Fukushima, Kei; Kubota, Takaharu; Kosugi, Tomomi; Takimoto-kamimura, Midori

2013-01-01

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

OpenAIRE

The recent nuclear accident in Japan revealed the confusion and the inadequate knowledge of the citizens about the issues of nuclear energy, nuclear applications, radioactivity and their consequences In this work we present the first results of an ongoing study which aims to evaluate the knowledge and the views of Greek undergraduate students on the above issues. A web based survey was conducted and 131 students from TEI Piraeus answered a multiple choice questionnaire with ...

Pilakouta, Mirofora

2011-01-01

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Doppler tomography  

International Nuclear Information System (INIS)

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

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Thermal expansion coefficient of glass and melts of Te-I system  

International Nuclear Information System (INIS)

Volumetric thermal expansion coefficient (VTEC) was studied in glasses and melts of (TeI)1-x (T2I)x system in the range 293-773 K. During heating to glass transition temperature VTEC of all studied glasses don't depend on temperature. VTEC for melts don't depend on temperature. This points to more high rigidity of structure as compared with Te-Cl and Te-Br systems. More significant rigidity of structure in studied system is conditioned by strengthening of intermolecular interaction increasing density of chain cross-linking. VTEC of glasses in given system are close to corresponding values of chain polymers

18

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

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

Science.gov (United States)

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…

Ritzmann, Sandrina; Hagemann, Vera; Kluge, Annette

2014-01-01

20

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

CERN Document Server

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

Pilakouta, Mirofora

2011-01-01

21

"Sonoelasticity" images derived from ultrasound signals in mechanically vibrated tissues.  

Science.gov (United States)

A method has been developed for detecting and imaging the relative "stiffness," or elasticity of tissues. Externally applied vibration at low frequencies (10-1000 Hz) is used to induce oscillations within soft tissues, and the motion is detected by Doppler ultrasound. The results are displayed in a format resembling conventional Doppler color flow mapping, and are termed "sonoelasticity images." Preliminary experiments indicate that these novel images may be useful for detecting hard tumors in the prostate, liver, breast, and other organs. PMID:1694603

Lerner, R M; Huang, S R; Parker, K J

1990-01-01

22

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

Directory of Open Access Journals (Sweden)

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

Vin Davis

2009-09-01

23

Soil and building material as main sources of indoor radon in B?i?a-?tei radon prone area (Romania)  

International Nuclear Information System (INIS)

Radon contributes to over than 50% of the natural radiation dose received by people. In radon risk areas this contribution can be as high as 90–95%, leading to an exposure to natural radiation 5–10 times higher than normal. This work presents results from radon measurements (indoor, soil and exhalation from building materials) in B?i?a-?tei, a former uranium exploitation area in NW Romania. In this region, indoor radon concentrations found were as high as 5000 Bq m?3 and soil radon levels ranged from 20 to 500 kBq m?3. An important contribution from building materials to indoor radon was also observed. Our results indicate two independent sources of indoor radon in the surveyed houses of this region. One source is coming from the soil and regular building materials, and the second source being uranium waste and local radium reached material used in building construction. The soil as source of indoor radon shows high radon potential in 80% of the investigated area. Some local building materials reveal high radon exhalation rate (up to 80 mBq kg?1 h?1 from a sandy-gravel material, ten times higher than normal material). These measurements were used for the radon risk classification of this area by combining the radon potential of the soil with the additional component from building materials. Our results indicate that B?i?a-?tei area can be categorized as a radon prone area.

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

Science.gov (United States)

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

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

2015-02-01

25

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

Science.gov (United States)

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.

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

26

Cosmology with Doppler Lensing  

CERN Document Server

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

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

2014-01-01

27

Piktnaudžiavimas dominuojan?ia pad?timi: piktnaudžiaujantys susiejimo veiksmai pagal Europos S?jungos ir Jungtini? Amerikos Valstij? konkurencijos teis?  

OpenAIRE

Šis darbas nagrin?ja piktnaudžiaujan?io susiejimo praktik? ir jos s?vok? pagal Europos S?jungos ir Jungtini? Amerikos Valstij? teis?s aktus. Autor? bando nustatyti piktnaudžiaujan?io susiejimo veiklos koncepcij? ir rasti susiejimo teisiniam ?vertinimui reikalingus elementus. Be to, autor? atlieka lyginam?j? analiz? Microsoft susiejimo bylos Europos S?jungos ir Jungtini? Amerikos Valstij? teismuose, su tikslu nustatyti ar tie patys elementai abiejose jurisdikcijose lemia...

Kazakevic?, Diana

2013-01-01

28

Doppler Lidar (DL) Handbook  

Energy Technology Data Exchange (ETDEWEB)

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

Newsom, RK

2012-02-13

29

Rotational Doppler Effect  

OpenAIRE

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

Halder, Amit

2002-01-01

30

Research & Medical Doppler platform  

OpenAIRE

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

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

2012-01-01

31

Rotational Doppler Effect  

CERN Document Server

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

Halder, A

2002-01-01

32

Image-derived input function for brain PET studies: many challenges and few opportunities  

OpenAIRE

Quantitative positron emission tomography (PET) brain studies often require that the input function be measured, typically via arterial cannulation. Image-derived input function (IDIF) is an elegant and attractive noninvasive alternative to arterial sampling. However, IDIF is also a very challenging technique associated with several problems that must be overcome before it can be successfully implemented in clinical practice. As a result, IDIF is rarely used as a tool to reduce invasiveness i...

Zanotti-fregonara, Paolo; Chen, Kewei; Liow, Jeih-san; Fujita, Masahiro; Innis, Robert B.

2011-01-01

33

Holographic laser Doppler ophthalmoscopy  

CERN Document Server

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

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

2010-01-01

34

Doppler Optical Coherence Tomography  

OpenAIRE

Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained impo...

Leitgeb, Rainer A.; Werkmeister, Rene? M.; Blatter, Cedric; Schmetterer, Leopold

2014-01-01

35

Doppler-musical instrument  

Energy Technology Data Exchange (ETDEWEB)

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 {mu}eV, even when the ultra-high energy resolution of {delta}E{approx}0.03 {mu}eV is attained. (author)

Sato, T.J. [National Research Institute for Metals, Tsukuba, Ibaraki (Japan); Watanabe, N. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Shibata, K. [Institute for Materials Research, Tohoku Univ., Sendai, Miyagi (Japan)

2001-03-01

36

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.

37

Laser double Doppler flowmeter  

Science.gov (United States)

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

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

2014-05-01

38

Clinical applications of doppler ultrasound  

Energy Technology Data Exchange (ETDEWEB)

This book introduces a guide to the physical principles and instrumentation of duplex Doppler ultrasound and its applications in obstetrics, gynecology, neonatology, gastroentology, and evaluation of peripheral vascular disease. The book provides information needed to perform Doppler ultrasound examinations and interpret the results. An introduction to Doppler physics and instrumentation is followed by a thorough review of hemodynamics, which explains the principles underlying interpretation of Doppler signals. Of special note is the state-of-the-art coverage of new applications of Doppler in recognition of high-risk pregnancy, diagnosis of intrauterine growth retardation, investigation of neonatal blood flow, evaluation of first-trimester pregnancy, and diagnosis of gastrointestinal disease. The book also offers guidelines on the use of Doppler ultrasound in diagnosing carotid disease, deep venous thrombosis, and aorta/femoral disease.

Taylor, K.J.W.; Burns, P.N.; Well, P.N.T.

1987-01-01

39

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

40

Comparisons between PW Doppler system and enhanced FM Doppler system  

DEFF Research Database (Denmark)

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

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

1995-01-01

41

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

42

Doppler Beats or Interference Fringes?  

Science.gov (United States)

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

Kelly, Paul S.

1979-01-01

43

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

CERN Document Server

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

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

2012-01-01

44

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

Directory of Open Access Journals (Sweden)

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

Gail Falkingham

2005-04-01

45

Estudo Doppler na hipertensão portal / Doppler evaluation in portal hypertension  

Scientific Electronic Library Online (English)

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

Márcio Martins, Machado; Ana Cláudia Ferreira, Rosa; Nestor de, Barros; Letícia Martins, Azeredo; Junia Beatriz Ferreira, Rosa; Luciana Mendes de Oliveira, Cerri; Maria Cristina, Chammas; Murilo Tavares, Daher; Renato Tavares, Daher; William Abrão, Saad; Giovanni Guido, Cerri.

2004-02-01

46

Doppler characteristics of sea clutter.  

Energy Technology Data Exchange (ETDEWEB)

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

Raynal, Ann Marie; Doerry, Armin Walter

2010-06-01

47

Continuous wave ultrasonic Doppler tomography  

OpenAIRE

In continuous wave ultrasonic Doppler tomography (DT), the ultrasonic beam moves relative to the scanned object to acquire Doppler-shifted frequency spectra which correspond to cross-range projections of the scattering and reflecting structures within the object. The relative motion can be circular or linear. These data are then backprojected to reconstruct the two-dimensional image of the object cross section. By using coherent processing, the spatial resolution of ultrasonic DT is close to ...

Liang, Haidong-dong; Tsui, Chun Sing Louis; Halliwell, Michael; Wells, Peter N. T.

2011-01-01

48

Adaptive Spectral Doppler Estimation  

DEFF Research Database (Denmark)

In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested and compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of matched filters (one for each veloc- ity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pul- sating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior per- formance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.

Gran, Fredrik; Jakobsson, Andreas

2009-01-01

49

Airborne Doppler lidar activities  

Science.gov (United States)

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

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

1985-01-01

50

Calculated T2 images derived from a multiple SE sequence, (2)  

International Nuclear Information System (INIS)

T2 images as currently utilized in clinical practice are generally obtined by calculation from two SE images having different parameters. We applied the least square estimation (LSE) to many SE images derived from a multiple SE sequence, to analyze T2 for individual pixels and to construct T2, M0 (0th echo intensity) and error approximation images. Using this method we can not only get high quality T2 and M0 images but also appraise the approximation accuracy. Analyses of the T2 values thus obtained for NiSO4 solution phantoms (spanning a T2 range of 40 to 1000 ms) indicate a good linear relation between NiSO4 conc. and 1/T2. The greater the number of SE used in the calculation, the smaller the T2 estimation error value of the calculated images. By utilizing an array processor, we could reduce the T2 calculation time to 2 or 3 minutes to construct a 256 x 256 image. (author)

51

Automatic Identification and Truncation of Boundary Outlets in Complex Imaging-Derived Biomedical Geometries  

Energy Technology Data Exchange (ETDEWEB)

Fast and accurate reconstruction of imaging-derived geometries and subsequent quality mesh generation for biomedical computation are enabling technologies for both clinical and research simulations. Often, the transformation of image to mesh is the rate-limiting step, requiring arduous manual manipulations. A challenging part of this process is the introduction of computable, orthogonal boundary patches, namely the outlets, into treed structures, such as vasculature, arterial or airway trees. Herein, we present efficient and robust algorithms for automatically identifying and truncating the outlets for complex biomedical geometries. Our approach is based on a conceptual decomposition of objects into three different types of local structures, including tips, segments, and branches, where the tips determine the outlets. We define the tips by introducing a novel geometric concept called the average interior center of curvature (AICC), and identify those that are physically stable and numerically noise resistant through successive inflation and deflation tests. We compute well-defined orthogonal planes, which truncate the tips into outlets. The rims of the outlets are then connected into curves, and the outlets are then closed using Delaunay triangulation with the curves as the boundary constraints. Our approach is efficient, with near linear time complexity. We illustrate the effectiveness and robustness of our approach with a variety of complex lung and coronary artery geometries.

Jiao, Xiangmin; Einstein, Daniel R.; Dyedov, Volodymyr; Carson, James P.

2009-09-01

52

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

Science.gov (United States)

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

da Silva, N. A.; Herzog, H.; Weirich, C.; Tellmann, L.; Rota Kops, E.; Hautzel, H.; Almeida, P.

2013-02-01

53

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

International Nuclear Information System (INIS)

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

54

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-07-15

55

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

56

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

Directory of Open Access Journals (Sweden)

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

Shiyuan LIU

2009-05-01

57

On the use of image-derived input functions in oncological fluorine-18 fluorodeoxyglucose positron emission tomography studies  

International Nuclear Information System (INIS)

There is growing interest in monitoring response to therapy in oncology patients using positron emission tomography and fluorine-18 fluorodeoxyglucose (FDG). Quantification is required, and various methods have been described. Arterial sampling, which provides the most accurate input function, often is not feasible in patients undergoing chemotherapy. In the thorax an image-derived input function can be obtained from the large vascular structures. In many studies the left ventricle (LV) is used, but the obtained data are rarely validated. In this study a simple quality control procedure for the image-derived input function was developed and compared with a standard LV curve. Twenty dynamic FDG scans were obtained in nine patients with non-small cell lung cancer stage IIIA-N2. Three venous blood samples were taken as a quality control for the image-derived input function. Regions of interest (ROIs) were defined for aorta, LV and left atrium. Input curves were generated according the the standard use of the LV curve and by applying the quality control method to all vascular ROIs. Tumour ROIs were defined and both input functions were used to calculate tumour glucose metabolism (MRglu), using both standard non-linear regression and Patlak analyses. Mean differences in MRglu using ''standard'' LV and ''quality control approved'' input functions were 16.2% and 17.5% for non-linear regression and Patlak analyses, respectively, iondicating that the use of ''standard'' LV curcating that the use of ''standard'' LV curve might lead to significant errors. It is concluded that care should be taken in using image derived input functions without appropriate quality control. The proposed procedure is simple and results in significantly more accurate MRglu data. (orig.)

58

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

Directory of Open Access Journals (Sweden)

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

Begoña Simal

2010-03-01

59

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

Directory of Open Access Journals (Sweden)

Full Text Available

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

Begoña Simal

2010-03-01

60

Doppler indicates of uterine artery Doppler velocimetry by placental location  

International Nuclear Information System (INIS)

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

61

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)

62

Doppler indicates of uterine artery Doppler velocimetry by placental location  

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-09-15

63

Spatial weighting of Doppler reactivity feedback  

International Nuclear Information System (INIS)

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

64

Analysis of Doppler lidar data  

Science.gov (United States)

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

Rothermel, J.

1985-01-01

65

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

Science.gov (United States)

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

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

2015-02-01

66

Avaliação dos tumores hepáticos ao Doppler Doppler evaluation of liver tumors  

Directory of Open Access Journals (Sweden)

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

Márcio Martins Machado

2004-10-01

67

Detection of microemboli by transcranial Doppler ultrasound.  

OpenAIRE

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

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

1996-01-01

68

Chromospheric Doppler Velocity Oscillations in a Sunspot  

OpenAIRE

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

Maurya, R. A.

2013-01-01

69

Luminosity Dependence and Search Doppler  

Science.gov (United States)

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

VanParadijs, Johannes A.

1998-01-01

70

Doppler photoacoustic and Doppler ultrasound in blood with optical contrast agent  

Science.gov (United States)

Photoacoustic Doppler flowmetry as well as Doppler ultrasound were performed in acoustic resolution regime on tubes filled with flowing blood with indocyanine green (ICG) at different concentrations. The photoacoustic excitation utilized a pair of directly-modulated fiber-coupled 830nm laser-diodes, modulated with either CW or tone-bursts for depthresolved measurements. The amplitude of the Doppler peak in photoacoustic Doppler measurements was found to be proportional to the ICG concentration. Photoacoustic Doppler was measured in ICG at human safe concentrations, but not in whole blood. Comparing the results between the two modalities implied that using a wavelength with higher optical absorption may improve the photoacoustic signal in blood.

Sheinfeld, Adi; Eyal, Avishay

2013-03-01

71

Doppler tomography in fusion plasmas and astrophysics  

DEFF Research Database (Denmark)

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

Salewski, Mirko; Geiger, B.

2015-01-01

72

Chromospheric Doppler Velocity Oscillations in a Sunspot  

Science.gov (United States)

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

Maurya, R. A.

2013-12-01

73

Microwave Doppler radar in unobtrusive health monitoring  

Science.gov (United States)

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.

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

2015-02-01

74

Doppler Resilient Waveforms with Perfect Autocorrelation  

CERN Document Server

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

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

2007-01-01

75

Color doppler sonography in thickened gallbladder wall  

International Nuclear Information System (INIS)

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

76

Lorentz Covariant Theory of Precise Doppler Measurements  

CERN Document Server

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.

Kopeikin, S M

1999-01-01

77

Chromospheric Doppler Velocity Oscillations in a Sunspot  

CERN Document Server

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

Maurya, R A

2013-01-01

78

Color doppler ultrasonography diagnosis of intramuscular hemangioma  

International Nuclear Information System (INIS)

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

79

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

DEFF Research Database (Denmark)

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.

Christensen, Anders Nymark; Reichkendler, Michala H.

2014-01-01

80

Intensity changes in the Doppler effect  

OpenAIRE

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

Johnson, Montgomery H.; Teller, Edward

1982-01-01

81

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

82

Determination of cardiac output by Doppler echocardiography.  

OpenAIRE

Cardiac output determined by Doppler echocardiography was compared with that determined by thermodilution at rest and during dobutamine infusion in 10 patients (group A) and by the Fick method at rest in 11 patients (group B). All patients had angina pectoris without valvular heart disease. Maximum spatial blood velocity and cross sectional aortic area were estimated by the Doppler technique and echocardiography. Cardiac output was calculated by multiplying blood velocity by aortic area at va...

Ihlen, H.; Amlie, J. P.; Dale, J.; Forfang, K.; Nitter-hauge, S.; Otterstad, J. E.; Simonsen, S.; Myhre, E.

1984-01-01

83

Doppler Imaging of Exoplanets and Brown Dwarfs  

OpenAIRE

Doppler Imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these objects in un- precedented detail. I present the first quantitative assessment of the prospects for Doppler Imaging of substellar objects with current facilities and with future giant ground-based telescopes. Observations will have the grea...

Crossfield, Ian J. M.

2014-01-01

84

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

85

Doppler Effect of Mechanical Waves and Light  

Directory of Open Access Journals (Sweden)

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

Jiacai Nie

2009-09-01

86

Microwave Doppler reflectometer system in LHD.  

Science.gov (United States)

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

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

2012-10-01

87

Color Doppler Ultrasound Indices in Endometriotic Cysts  

Directory of Open Access Journals (Sweden)

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

Parisa Hajialioghlo

2009-01-01

88

Estimating the Doppler centroid of SAR data  

DEFF Research Database (Denmark)

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

Madsen, SØren NØrvang

1989-01-01

89

Doppler evaluation of valvular regurgitation  

International Nuclear Information System (INIS)

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

90

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

Science.gov (United States)

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

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

2012-12-01

91

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

Science.gov (United States)

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

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

2012-12-01

92

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

Scientific Electronic Library Online (English)

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

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

2004-10-01

93

Doppler-guided retrograde catheterization system  

Science.gov (United States)

The purpose of this study was to investigate a Doppler guided catheterization system as an adjunctive or alternative methodology to overcome the disadvantages of left heart catheterization and angiography. These disadvantages include the biological effects of radiation and the toxic and volume effects of iodine contrast. Doppler retrograde guidance uses a 20 MHz circular pulsed Doppler crystal incorporated into the tip of a triple lumen multipurpose catheter and is advanced retrogradely using the directional flow information provided by the Doppler waveform. The velocity detection limits are either 1 m/second or 4 m/second depending upon the instrumentation. In a physiologic flow model of the human aortic arch, multiple data points revealed a positive wave form when flow was traveling toward the catheter tip indicating proper alignment for retrograde advancement. There was a negative wave form when flow was traveling away from the catheter tip if the catheter was in a branch or bent upon itself indicating improper catheter tip position for retrograde advancement. In a series of six dogs, the catheter was able to be accurately advanced from the femoral artery to the left ventricular chamber under Doppler signal guidance without the use of x-ray. The potential applications of a Doppler guided retrograde catheterization system include decreasing time requirements and allowing safer catheter guidance in patients with atherosclerotic vascular disease and suspected aortic dissection. The Doppler system may allow left ventricular pressure monitoring in the intensive care unit without the need for x-ray and it may allow left sided contrast echocardiography. With pulse velocity detection limits of 4 m/second, this system may allow catheter direction and passage into the aortic root and left ventricle in patients with aortic stenosis. A modification of the Doppler catheter may include transponder technology which would allow precise catheter tip localization once the catheter tip is placed in the aortic root. Such technology may conceivably assist in allowing selective coronary catheterization. These studies have demonstrated that Doppler guided retrograde catheterization provides an accurate method to catheterization the aortic root and left ventricular chamber without x-ray. In humans, it may prove useful in a variety of settings including the development of invasive ultrasonic diagnostic and therapeutic technology.

Frazin, Leon J.; Vonesh, Michael J.; Chandran, Krishnan B.; Khasho, Fouad; Lanza, George M.; Talano, James V.; McPherson, David D.

1991-05-01

94

The EVE Doppler Sensitivity and Flare Observations  

Science.gov (United States)

The Extreme-ultraviolet Variability Experiment (EVE; see Woods et al., 2009) obtains continuous EUV spectra of the Sun viewed as a star. Its primary objective is the characterization of solar spectral irradiance, but its sensitivity and stability make it extremely interesting for observations of variability on time scales down to the limit imposed by its basic 10 s sample interval. In this paper we characterize the Doppler sensitivity of the EVE data. We find that the 30.4 nm line of He ii has a random Doppler error below 0.001 nm (1 pm, better than 10 km s-1 as a redshift), with ample stability to detect the orbital motion of its satellite, the Solar Dynamics Observatory (SDO). Solar flares also displace the spectrum, both because of Doppler shifts and because of EVE's optical layout, which (as with a slitless spectrograph) confuses position and wavelength. As a flare develops, the centroid of the line displays variations that reflect Doppler shifts and therefore flare dynamics. For the impulsive phase of the flare SOL2010-06-12, we find the line centroid to have a redshift of 16.8 ± 5.9 km s-1 relative to that of the flare gradual phase (statistical errors only). We find also that high-temperature lines, such as Fe xxiv 19.2 nm, have well-determined Doppler components for major flares, with decreasing apparent blueshifts as expected from chromospheric evaporation flows.

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

2011-10-01

95

Doppler radar imaging of spherical planetary surfaces  

International Nuclear Information System (INIS)

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

96

Development of the doppler electron velocimeter: theory.  

Energy Technology Data Exchange (ETDEWEB)

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

Reu, Phillip L.

2007-03-01

97

Doppler flow patterns in pediatric pulmonary pathology  

International Nuclear Information System (INIS)

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

98

Doppler tomography by total variation minimization  

Science.gov (United States)

We have developed a new model of Doppler tomography using total variation minimization (DTTVM). This method can reconstruct localized and nonaxisymmetric profiles with sharp edges in the Doppler map. This characteristic is emphasized in the case where input data are small in number. We apply this model to natural data for the dwarf nova WZ Sge in superoutburst and TU Men in quiescence. We confirm that DTTVM can reproduce the observed spectra with high precision. Compared with the models based on the maximum entropy method, our new model can provide Doppler maps that little depend on the hyperparameter and on the presence of the absorption core. We also introduce a cross-validation method of estimating reasonable values of a hyperparameter in the model from the data themselves.

Uemura, Makoto; Kato, Taichi; Nogami, Daisaku; Mennickent, Ronald

2015-04-01

99

Doppler US evaluation of the obstetric patient  

International Nuclear Information System (INIS)

A continuous-wave Doppler US device was used to evaluate the umbilican and uterine artery wave forms in pregnancy. The A/B ratio (peak systolic frequency shift divided by the lowest diastolic frequency shift) of the patients in this study were compared with known standards determined in pregnant women of similar gestational status. The wave form data were correlated with the outcome of pregnancy. In 73% of pregnancies with abnormal outcomes, one or both wave forms were abnormal (73% sensitivity). The specificity of the examination was 96%. Although a negative Doppler US examination does not completely exclude the possibility of an abnormal pregnancy outcome, there is a strong correlation between a positive Doppler US study and an abnormal outcome

100

Doppler Tomography by Total Variation Minimization  

CERN Document Server

We have developed a new model of the Doppler tomography using total variation minimization (DTTVM). This method can reconstruct localized and non-axisymmetric profiles having sharp edges in the Doppler map. This characteristic is emphasized in the case that the number of the input data is small. We apply this model to real data of the dwarf novae, WZ Sge in superoutburst and TU Men in quiescence. We confirmed that DTTVM can reproduce the observed spectra with a high precision. Compared with the models based on the maximum entropy method, DTTVM provides the Doppler maps that little depend on the hyper-parameter and on the presence of the absorption core. We also introduce a cross-validation method to estimate reasonable values of a hyperparameter in the model by the data itself.

Uemura, Makoto; Nogami, Daisaku; Mennickent, Ronald

2014-01-01

101

Doppler tomography by total variation minimization  

Science.gov (United States)

We have developed a new model of Doppler tomography using total variation minimization (DTTVM). This method can reconstruct localized and nonaxisymmetric profiles with sharp edges in the Doppler map. This characteristic is emphasized in the case where input data are small in number. We apply this model to natural data for the dwarf nova WZ Sge in superoutburst and TU Men in quiescence. We confirm that DTTVM can reproduce the observed spectra with high precision. Compared with the models based on the maximum entropy method, our new model can provide Doppler maps that little depend on the hyperparameter and on the presence of the absorption core. We also introduce a cross-validation method of estimating reasonable values of a hyperparameter in the model from the data themselves.

Uemura, Makoto; Kato, Taichi; Nogami, Daisaku; Mennickent, Ronald

2015-03-01

102

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

International Nuclear Information System (INIS)

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

103

Laser Doppler velocimeter aerial spray measurements  

Science.gov (United States)

An experimental research program for measuring the location, spatial extent, and relative concentration of airborne spray clouds generated by agricultural aircraft is described. The measurements were conducted with a ground-based laser Doppler velocimeter. The remote sensing instrumentation, experimental tests, and the results of the flight tests are discussed. The cross section of the aerial spray cloud and the observed location, extent, and relative concentration of the airborne particulates are presented. It is feasible to use a mobile laser Doppler velocimeter to track and monitor the transport and dispersion of aerial spray generated by an agricultural aircraft.

Zalay, A. D.; Eberle, W. R.; Howle, R. E.; Shrider, K. R.

1978-01-01

104

Laser Doppler And Range Systems For Spacecraft  

Science.gov (United States)

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.

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

1990-01-01

105

Fish embryo multimodal imaging by laser Doppler digital holography  

CERN Document Server

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

Verrier, Nicolas; Picart, Pascal; Gross, Michel

2015-01-01

106

Doppler colour flow mapping: technology in search of an application?  

OpenAIRE

Although Doppler colour flow mapping may considerably reduce the need for conventional pulsed Doppler examination, quantitative flow measurements (particularly by continuous wave Doppler) are still essential in the evaluation of many conditions such as aortic stenosis. Doppler colour flow mapping is an important addition to the accurate non-invasive evaluation of several haemodynamic disorders of the heart and, as the technology improves, the range of applications will undoubtedly increase. A...

Monaghan, M. J.; Mills, P.

1989-01-01

107

Three-dimensional power Doppler angiography  

Science.gov (United States)

The purpose of the present study is to improve the quantification of peripheral arterial stenosis using 3D power Doppler angiography and investigate the potential of this technique for generating the arterial tree of the lower limb for surgery planning. Stenotic wall-less agar arteries were created to simulate the femoral and carotid arteries. 3D power Doppler angiograms of those arteries were generated under different hemodynamic conditions using a 3D ultrasound imaging system developed by the Life Imaging System Inc. The effect of multiple stenoses on the 3D power Doppler angiograms was investigated using the femoral arterial phantoms. Using the carotid arterial phantoms, 3D power Doppler angiograms of the carotid arteries were generated and compared with the known geometry. To image a whole lower limb arterial tree for lower limb salvage surgery planning, multiple scans are required to cover the entire field-of- view interested by using a water-coupled scanner. Preliminary in vivo test was performed using water-coupled scanning.

Guo, Zhenyu; Durand, Louis-Gilles; Holdsworth, David W.; Fenster, Aaron

1997-05-01

108

Parameter estimation based on Doppler frequency shifts  

Science.gov (United States)

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

Statman, Joseph I.; Rodemich, Eugene R.

1987-01-01

109

HF Doppler Radar Observations of Geomagnetic Pulsations.  

Czech Academy of Sciences Publication Activity Database

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

Fišer, Ji?í; Chum, Jaroslav

110

The Doppler effect measurement on 238U  

International Nuclear Information System (INIS)

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

111

[Hemotachymetry by Doppler effect (author's transl)].  

Science.gov (United States)

Transcutaneous hemotachymetry by ultrasonic Doppler effect is a simple, rapid, atraumatic and inexpensive method for obtaining hemodynamic data from cervical arteries; it is immensely useful for diagnosis of circulatory disorders. The author consider the physical principles of the method, its advantages and its drawbacks. Reproducibility and normal hemodynamic values are discussed. PMID:749514

Depresseux, J C

1978-01-01

112

Doppler instrumentation for measuring blood velocity and flow  

Science.gov (United States)

Doppler ultrasonic blood flowmeters are reviewed in detail. The importance of measurement accuracy for transcutaneous flowmeters and their clinical application is stressed. Doppler imaging was combined with conventional pulse echo imaging, and diagnostic information was extracted from flow signals. The range and extent of applications of Doppler instruments was also presented.

Gill, R. W.; Hottinger, C. F.; Meindl, J. D.

1975-01-01

113

Equipment for flow measurements according to the ultrasonic Doppler method  

International Nuclear Information System (INIS)

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

114

Improved transverse flow estimation using differential maximum Doppler frequency.  

Science.gov (United States)

Conventional Doppler technique can only provide the axial component of the blood flow vector, which is actually a three dimensional (3-D) quantity. To acquire the complete flow vector, estimations of the other two velocity components are essential. For the two dimensional (2-D) Doppler-bandwidth-based transverse estimation, however, accuracy is generally limited because of the complex dependence of the Doppler spectral shape on the flow variation within the sample volume. Two factors that may lead to the Doppler spectral change were considered in this study. One is the position offset of the sample volume and the other is the length of the sample volume. Simulations were performed and experimental data were also collected. Results indicate that the position offset may result in severe underestimation of Doppler shift frequency. Consequently, Doppler bandwidth is overestimated when it is determined by the difference between Doppler shift frequency and maximum Doppler frequency. Compared with the position offset, influence of the length of sample volume on the Doppler bandwidth is minor. To overcome this problem, a novel method, which is based on the differential maximum Doppler frequency, is proposed. Specifically, two beams with different beam widths are simultaneously generated to observe the blood flow and the difference between the corresponding maximum Doppler frequencies is used to estimate the transverse velocity. It is demonstrated that the accuracy and stability of transverse estimation are significantly improved by the proposed method even when the position offset is present. PMID:17208352

Shen, Che-Chou; Chou, Ching-Han; Wang, Yu-Chun

2007-03-01

115

Use of power Doppler in pediatric neurosonography: a pictorial essay.  

Science.gov (United States)

In pediatric neurosonography, conventional color Doppler imaging has been the primary adjunct to routine gray-scale imaging. Power Doppler sonography is a relatively recent development that does not have the limitations of conventional color Doppler ultrasound. The power Doppler technique measures the energy of moving red blood cells instead of the velocity and direction of flow. Advantages of this technique include increased sensitivity for identifying flow in slow-flow states, more complete evaluation of a vessel, and more accurate evaluation of the course of the vessel. Power Doppler sonography is helpful in evaluation of the neonatal brain in a variety of clinical situations: identifying the exact locations of extraaxial fluid collections, differentiating intraventricular clot from normal choroid plexus, detecting intraventricular hemorrhage, and demonstrating asymmetries in cerebral perfusion. However, in certain difficult cases, use of both conventional color Doppler sonography and power Doppler sonography produces increased diagnostic accuracy because these techniques furnish complementary information. PMID:9672972

Seibert, J J; Avva, R; Hronas, T N; Mocharla, R; Vanderzalm, T; Cox, K; Kinder, D; Lidzy, B; Knight, K L

1998-01-01

116

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.)

117

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

118

Renal duplex Doppler ultrasound findings in diabetics  

International Nuclear Information System (INIS)

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

119

Design of a Doppler reflectometer for KSTAR  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-11-15

120

Transcranial Doppler sonography in familial hemiplegic migraine  

Energy Technology Data Exchange (ETDEWEB)

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

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

1991-02-01

121

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

122

Design of a Doppler reflectometer for KSTARa)  

Science.gov (United States)

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

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

2014-11-01

123

Design of a Doppler reflectometer for KSTAR.  

Science.gov (United States)

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

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

2014-11-01

124

Color Doppler US of the penis  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-07-01

125

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

126

Monitoring of renal allografts by Doppler ultrasound  

OpenAIRE

Cyclosporin (CyA) associated renal dysfunction may be due to an arteriolopathy which reduces graft perfusion. We have prospectively monitored 27 renal allograft recipients, within 30 days of transplantation, by continuous wave Doppler ultrasound. Changes in the frequency shift waveform should indicate alterations in renal blood flow. Objective analysis was made in 112 waveforms by determining the ratio of the area under the frequency shift/time curve of the first half and the second half of t...

Canning, C. R.

1988-01-01

127

Measurement of aortic regurgitation by Doppler echocardiography.  

OpenAIRE

In an attempt to develop a new approach to the non-invasive measurement of aortic regurgitation, transmitral volumetric flow (MF) and left ventricular total stroke volume (SV) were measured by Doppler and cross sectional echocardiography in 23 patients without aortic valve disease (group A) and in 26 patients with aortic regurgitation (group B). The transmitral volumetric flow was obtained by multiplying the corrected mitral orifice area by the diastolic velocity integral, and the left ventri...

Zhang, Y.; Nitter-hauge, S.; Ihlen, H.; Rootwelt, K.; Myhre, E.

1986-01-01

128

Sub-Nyquist Radar via Doppler Focusing  

OpenAIRE

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

Bar-ilan, Omer; Eldar, Yonina C.

2012-01-01

129

Doppler Findings in Intrapartum Fetal Distress  

OpenAIRE

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

Khatereh Tooba; Laleh Eslamian

2011-01-01

130

Phase Doppler droplet sizing: Scattering angle effects  

Energy Technology Data Exchange (ETDEWEB)

The phase Doppler technique is an LDV-based method for the nonintrusive, simultaneous measurement of particle size, velocity, and concentration. It is becoming a standard device for measurement of spray droplets in air as well as cavitation nuclei bubbles in water. The Phase Doppler Particle Analyzer (PDPA) is a commercial phase Doppler instrument. Previous calibrations of the PDPA using well-characterized liquid droplets have revealed nonlinearity of the instrument response for droplet diameters less than 20 {mu}m. For many applications, droplet sizing accuracy in the small diameter range is critical. Light scattering calculations performed by the instrument manufacturer suggest two theoretical approaches to improving the instrument response in this size range: optimizing the collection angle and increasing the collection area. The first approach has been tested experimentally. This paper presents size calibrations of the PDPA with the receiver configured at two angles: 30{degree} (the standard configuration) and 70{degree} off-forward axis. The calibration was performed with monodisperse oleic acid droplets in the diameter range 3.7 to 32 {mu}m. As in earlier calibration studies, the 30{degree} configuration resulted in marked nonlinearity in instrument response below 20 {mu}m. Oscillations were still apparent for the 70{degree} configuration, which showed only a modest improvement compared to the response at 30{degree}. 7 refs., 5 figs.

Ceman, D.L.; O' Hern, T.J.; Rader, D.J.

1990-01-01

131

Precise Doppler Monitoring of Barnard's Star  

CERN Document Server

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

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

2012-01-01

132

Doppler Lidar for Wind Measurements on Venus  

Science.gov (United States)

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

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

2010-01-01

133

Doppler angle correction in the measurement of intrarenal parameters  

Directory of Open Access Journals (Sweden)

Full Text Available Jing Gao¹, Keith Hentel¹, Qiang Zhu², Teng Ma², George Shih¹, Kevin Mennitt¹, Robert Min¹¹Department of Radiology, New York Presbyterian Hospital, Weill Cornell Medical College, NY, USA; ²Division of Diagnostic Ultrasound, Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, ChinaBackground: The aim of this study was to assess differences in intrarenal artery Doppler parameters measured without and with Doppler angle correction.Methods: We retrospectively reviewed color duplex sonography in 30 normally functioning kidneys (20 native kidneys in 10 subjects and 10 transplanted kidneys in 10 subjects performed between January 26, 2010 and July 26, 2010. There were 10 age-matched men and10 age-matched women (mean 39.8 ± 12.2, range 21–60 years in this study. Depending on whether the Doppler angle was corrected in the spectral Doppler measurement, Doppler parameters including peak systolic velocity (PSV, end-diastolic velocity (EDV, and resistive index (RI measured at the interlobar artery of the kidney were divided into two groups, ie, initial Doppler parameters measured without Doppler angle correction (Group 1 and remeasured Doppler parameters with Doppler angle correction (Group 2. Values for PSV, EDV, and RI measured without Doppler angle correction were compared with those measured with Doppler angle correction, and were analyzed statistically with a paired-samples t-test.Results: There were statistical differences in PSV and EDV at the interlobar artery in the upper, mid, and lower poles of the kidney between Group 1 and Group 2 (all P < 0.001. PSV and EDV in Group 1 were significantly lower than in Group 2. RI in Group 1 was the same as that in Group 2 in the upper, mid, and lower poles of the kidneys.Conclusion: Doppler angle correction plays an important role in the accurate measurement of intrarenal blood flow velocity. The true flow velocity converted from the maximum Doppler velocity shift is produced only when the Doppler angle is 0°, so that the emission sound beam is parallel to the direction of blood flow at the sampled artery. Therefore, the Doppler angle correction should be routinely applied and displayed on renal color duplex sonography.Keywords: color duplex sonography, blood flow velocity, Doppler angle, Doppler shift, kidney

Mennitt K

2011-03-01

134

A 94-GHz Doppler radar for cloud observations  

Science.gov (United States)

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

Lhermitte, Roger

1987-03-01

135

Doppler US evaluation of the hypertensive portal system  

International Nuclear Information System (INIS)

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

136

Applications of Doppler ultrasound in clinical vascular disease  

Science.gov (United States)

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

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

1975-01-01

137

Is tissue Doppler echocardiography the Holy Grail for the intensivist?  

OpenAIRE

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

Poelaert, Jan; Roosens, Carl

2007-01-01

138

Spectral Doppler of the hepatic veins in pulmonary hypertension.  

Science.gov (United States)

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

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

2015-01-01

139

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

Directory of Open Access Journals (Sweden)

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

Luca Giugno

2007-05-01

140

Power Doppler - Principles and Potential Clinical Applications  

OpenAIRE

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

Nilsson, Anders

2003-01-01

141

Tecnología Doppler y movimientos respiratorios fetales  

Scientific Electronic Library Online (English)

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

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

2008-03-01

142

[Color Doppler sonography of focal abdominal lesions].  

Science.gov (United States)

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

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

2004-01-01

143

Doppler cooling to the Quantum limit  

CERN Document Server

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

Chalony, Maryvonne; Klappauf, Bruce; Wilkowski, David

2011-01-01

144

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-11-01

145

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2002-07-01

146

Ambiguity resolution for satellite Doppler positioning systems  

Science.gov (United States)

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

Argentiero, P.; Marini, J.

1979-01-01

147

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.

148

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

149

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.

150

Cardiac tissue Doppler in steroid users.  

Science.gov (United States)

Anabolic steroids cause a variety of side effects, among them a slight concentric left ventricular hypertrophy. The objective of the present study was to clarify if they also induce alterations in left ventricular function. 14 male body builders with substantial intake of anabolic steroids (users) were examined by standard echocardiography and cardiac tissue Doppler imaging. They were compared to 11 steroid-free strength athletes (non-users) and 15 sedentary control subjects. Users showed an increased left ventricular muscle mass index. The ratio of peak transmitral blood flow velocities during early diastolic filling and atrial contraction did not differ between groups (users: 1.4 +/- 0.3; non-users: 1.7 +/- 0.5; controls: 1.4 +/- 0.4). In contrast an analogous tissue Doppler parameter, the ratio of myocardial velocities during early and late ventricular filling in the basal septum, was significantly lower in users (1.2 +/- 0.4) when compared to non-users (1.6 +/- 0.5) or controls (1.6 +/- 0.6). The velocity gradient during myocardial E-wave in the posterior wall showed significantly lower values in users (3.8 +/- 1.3 1/s) as compared to controls (5.8 +/- 2.5 1/s). There were no differences in systolic function. Summarizing strength athletes abusing anabolic steroids show negative alterations in diastolic function. PMID:17549658

Krieg, A; Scharhag, J; Albers, T; Kindermann, W; Urhausen, A

2007-08-01

151

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)

152

Cervicocranial artery dissection. Detection by Doppler ultrasound and MR angiography  

Energy Technology Data Exchange (ETDEWEB)

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

Bakke, S.J. [Dept. of Radiology, National Hospital, Univ. Oslo (Norway); Smith, H.J. [Dept. of Radiology, National Hospital, Univ. Oslo (Norway); Kerty, E. [Dept. of Neurology, National Hospital, Univ. Oslo (Norway); Dahl, A. [Dept. of Neurology, National Hospital, Univ. Oslo (Norway)

1996-07-01

153

Cervicocranial artery dissection. Detection by Doppler ultrasound and MR angiography  

International Nuclear Information System (INIS)

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

154

Optimized doppler optical coherence tomography for choroidal capillary vasculature imaging  

Science.gov (United States)

In this paper, we analyzed the retinal and choroidal blood vasculature in the posterior segment of the human eye with optimized color Doppler and Doppler variance optical coherence tomography. Depth-resolved structure, color Doppler and Doppler variance images were compared. Blood vessels down to capillary level were able to be obtained with the optimized optical coherence color Doppler and Doppler variance method. For in-vivo imaging of human eyes, bulkmotion induced bulk phase must be identified and removed before using color Doppler method. It was found that the Doppler variance method is not sensitive to bulk motion and the method can be used without removing the bulk phase. A novel, simple and fast segmentation algorithm to indentify retinal pigment epithelium (RPE) was proposed and used to segment the retinal and choroidal layer. The algorithm was based on the detected OCT signal intensity difference between different layers. A spectrometer-based Fourier domain OCT system with a central wavelength of 890 nm and bandwidth of 150nm was used in this study. The 3-dimensional imaging volume contained 120 sequential two dimensional images with 2048 A-lines per image. The total imaging time was 12 seconds and the imaging area was 5x5 mm2.

Liu, Gangjun; Qi, Wenjuan; Yu, Lingfeng; Chen, Zhongping

2011-03-01

155

A Doppler system for dynamic vector velocity maps.  

Science.gov (United States)

The aim of the vector Doppler technique is the quantitative reconstruction of a velocity field independently of the ultrasonic probe axis to flow angle. In particular, vector Doppler is interesting for studying vascular pathologies related to complex blood flows. A problem of vector Doppler is data representation in real-time that should be easy to interpret for the physician. In this work, we present a technique for dynamic display of vector velocity maps and some experimental results obtained in vitro with 2-D vector Doppler on flow phantoms reproducing complex flow conditions. An improvement in the map presentation was obtained by using velocity vector field interpolation. In this work, we considered the problem of spatial sampling for vector Doppler, establishing a relationship between sampling steps and scanning system characteristics. Finally, we developed a novel multimedia solution that uses both interpolated images and sound to discriminate between laminar and turbulent flows. PMID:11937287

Capineri, Lorenzo; Scabia, Marco; Masotti, Leonardo

2002-02-01

156

Use of GPS network data for HF Doppler measurements interpretation  

CERN Document Server

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

Petrova, Inna R; Latypov, Ruslan R

2014-01-01

157

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.

158

Airborne Doppler-lidar and ground-based Doppler radar observations of a thunderstorm in Oklahoma  

Science.gov (United States)

The results of airborne Doppler-lidar and ground-based Doppler radar observations of multicellular storms, marked by heavy rainfall, strong surface outflow, and a gust-front tornado, on June 30, 1981 are analyzed. The airborne lidar comprised a CO2-laser operating in the IR region, which was discharged once each second at 20 deg fore and aft, alternatively, of the normal to the aircraft's heading, and a quarter-wave plate for registering the returning frequency-shifted beams. Wind fields are plotted taking into account the advection effects. The lidar data set is noted for its self-consistency, though limited to a range of 5 km by the high moisture levels. Fair agreement was found between the lidar-derived and radar-derived average ground-based radial wind fields, with discrepancies on the order of 1.5 m/s.

Bluestein, H. B.; Mccaul, E. W., Jr.; Fitzjarrald, D. E.

1983-01-01

159

The recondite intricacies of Zeeman Doppler mapping  

CERN Document Server

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

Stift, M J; Cowley, C R

2011-01-01

160

Microscale Heat Conduction Models and Doppler Feedback  

Energy Technology Data Exchange (ETDEWEB)

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

Hawari, Ayman I.; Ougouag, Abderrafi

2015-01-22

161

Implementation of Doppler backscattering for MAST  

CERN Document Server

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

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

2014-01-01

162

Transcranial doppler, EEG and SEP monitoring  

Directory of Open Access Journals (Sweden)

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

A. Opp

2009-07-01

163

Widefield laser doppler velocimeter: development and theory.  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-03-01

164

LISA data analysis; 1, Doppler demodulation  

CERN Document Server

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

Cornish, N; Cornish, Neil; Larson, Shane

2003-01-01

165

Planar Particle Imaging Doppler Velocimetry Developed  

Science.gov (United States)

Two current techniques exist for the measurement of planar, three-component velocity fields. Both techniques require multiple views of the illumination plane in order to extract all three velocity components. Particle image velocimetry (PIV) is a high-resolution, high accuracy, planar velocimetry technique that provides valuable instantaneous velocity information in aeropropulsion test facilities. PIV can provide three-component flow-field measurements using a two-camera, stereo viewing configuration. Doppler global velocimetry (DGV) is another planar velocimetry technique that can provide three component flow-field measurements; however, it requires three detector systems that must be located at oblique angles from the measurement plane. The three-dimensional configurations of either technique require multiple (DGV) or at least large (stereo PIV) optical access ports in the facility in which the measurements are being conducted. Optical access is extremely limited in aeropropulsion test facilities. In many cases, only one optical access port is available. A hybrid measurement technique has been developed at the NASA Glenn Research Center, planar particle image and Doppler velocimetry (PPIDV), which combines elements from both the PIV and DGV techniques into a single detection system that can measure all three components of velocity across a planar region of a flow field through a single optical access port. In the standard PIV technique, a pulsed laser is used to illuminate the flow field at two closely spaced instances in time, which are recorded on a "frame-straddling" camera, yielding a pair of single-exposure image frames. The PIV camera is oriented perpendicular to the light sheet, and the processed PIV data yield the two-component velocity field in the plane of the light sheet. In the standard DGV technique, an injection-seeded Nd:YAG pulsed laser light sheet illuminates the seeded flow field, and three receiver systems are used to measure three components of velocity. The receiver systems are oriented at oblique angles to the light sheet in order to accurately resolve the three-component velocity. Each DGV receiver system contains two cameras, which share a common view of the illuminated flow through a beam-splitting cube. One camera views the illuminated flow directly (reference camera) and the second camera images the illuminated flow through an iodine vapor cell (signal camera). The laser frequency (wavelength) is adjusted so that the Doppler-shifted light from particles in the flow falls on an iodine absorption feature, see the following graph. The iodine vapor cell acts as a frequency-to-velocity filter by modulating the intensity of the transmitted light as a function of the flow velocity (Doppler shift). The ratio of the signal and reference images yields the component of the flow velocity along the bisector of the laser sheet propagation direction and the receiver system observation direction. The hybrid system employs a single-component DGV receiver system configured to simultaneously acquire PIV image data, as shown in the following diagram. The cameras used in the DGV receiver are replaced with PIV frame-straddling cameras, and the receiver system views the illuminated light sheet plane at 90 (as in the standard PIV configuration).

Wernet, Mark P.

2000-01-01

166

Laser Doppler vibrometry: new ENT applications  

Science.gov (United States)

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

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

1996-12-01

167

Role of colour doppler sonography in adnexal masses  

Directory of Open Access Journals (Sweden)

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

Shazia Ashraf Khan, Aamina Banoo

2014-04-01

168

Pulsed Doppler echocardiographic analysis of mitral regurgitation after myocardial infarction.  

Science.gov (United States)

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

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

1986-10-01

169

Sub-Doppler laser cooling of potassium atoms  

CERN Document Server

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.

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

2011-01-01

170

Sub-Doppler laser cooling of potassium atoms  

Energy Technology Data Exchange (ETDEWEB)

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.

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

171

Assessment of human tumor vascularity: Doppler color flow mapping  

International Nuclear Information System (INIS)

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

172

Recommended ENTREE S-band and Doppler models  

Science.gov (United States)

Based on comparisons between instantaneous and light time delay (LTD) formulations for S band range and Doppler observables, expanded models for instantaneous S band observables are recommended for inclusion in the ENTREE program. In a worst case situation using Guam tracking for a representative shuttle entry trajectory, the proposed ENTREE model differs from the LTD model by approximately + or - 0.2 ft in range and + or - 0.02 Hz in Doppler. In contrast, the maximum differences between the existing ENTREE model and the LTD model are approximately (-80, +60) ft in range and (-4, -1) Hz in Doppler.

Kelly, G. M.

1980-01-01

173

Measurement depth and volume in laser Doppler flowmetry  

OpenAIRE

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

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

2009-01-01

174

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

175

Advances in Direct Detection Doppler Lidar Technology and Techniques  

Science.gov (United States)

In this paper we will describe the ground based Doppler lidar system which is mounted in a modified delivery van to allow field deployment and operations. The system includes an aerosol double edge receiver optimized for aerosol backscatter Doppler measurements at 1064 nm and a molecular double edge receiver which operates at 355 nm. The lidar system will be described including details of the injection seeded diode pumped laser transmitter and the piezoelectrically tunable high spectral resolution Fabry Perot etalon which is used to measure the Doppler shift. Examples of tropospheric wind profiles obtained with the system will also be presented to demonstrate its capabilities.

Gentry, Bruce; Einaudi, Franco (Technical Monitor)

2001-01-01

176

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

Science.gov (United States)

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

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

2014-05-01

177

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

178

The Next Generation Airborne Polarimetric Doppler Radar  

Science.gov (United States)

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

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

2013-04-01

179

Doppler study of cerebral arteries in hypercholesterolemia  

Directory of Open Access Journals (Sweden)

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

Farhoudi M

2011-03-01

180

Doppler Signatures of the Atmospheric Circulation on Hot Jupiters  

CERN Document Server

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

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

2013-01-01

181

Value of intraplacental villous artery Doppler measurements in severe preeclampsia.  

Directory of Open Access Journals (Sweden)

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

Lacin S

1996-10-01

182

Micro-Doppler processing for ultra-wideband radar data  

Science.gov (United States)

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

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

2012-06-01

183

Laser Doppler technology applied to atmospheric environmental operating problems  

Science.gov (United States)

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

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

1976-01-01

184

Radiowave Phase Scintillation and Precision Doppler Tracking of Spacecraft  

Science.gov (United States)

Phase scintillation cause by propagation through irregularities in the solar wind, ionosphere, and tropospher, introduces noise in spacecraft radio science experiments. The observations reported here are uses to refine the propagation noise model for Doppler tracking of deep space probes.

Armstrong, J. W.

1997-01-01

185

Cerebral infarction following a carotid Doppler ultrasound: a chance association?  

OpenAIRE

The authors present a case report of a 64-year-old lady with multiple risk factors for atherosclerosis, who suffered an ischaemic stroke immediately following carotid Doppler ultrasound despite therapeutic warfarin and antiplatelet therapy. This event was only 16 days after the patient suffered a first ischaemic stroke during diagnostic coronary angiography following a syncopal episode accompanied with a raised troponin-T. The temporal relationship between the carotid Doppler ultrasound and s...

Roberton, Andrew; Shinton, Roger; Clow, Laura; Tudway, David

2012-01-01

186

Equine corpus luteum vascular evaluation by power-doppler ultrasound  

OpenAIRE

A ecografia com recurso Doppler é uma tecnologia emergente que tem demonstrado ter potencial para melhorar as capacidades de diagnóstico dos veterinários de equinos. Esta tecnologia baseia-se nos príncipios do Doppler, onde as frequências de ultra-som estão dependentes do movimento dos eritrócitos dentro dos vasos sanguíneos. A função do Corpo Lúteo (CL) está dependente do aporte sanguíneo, o qual fornece não só percursores esteroides mas também permite liberta?...

Gomes, Tiago Joa?o Da Silva

2008-01-01

187

Special Theory of Relativity through the Doppler Effect  

OpenAIRE

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

Moriconi, M.

2006-01-01

188

Color doppler ultrasound diagonosis in cesarean scar pregnancy  

International Nuclear Information System (INIS)

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

189

Doppler ultrasonographic changes in the canine kidney during normovolaemic anaemia  

OpenAIRE

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

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

2006-01-01

190

Changes in left ventricular stroke volume measured by Doppler echocardiography.  

OpenAIRE

Cardiac stroke volume was measured simultaneously by Doppler echocardiography and thermodilution in 20 patients with coronary artery disease. Stroke volume as determined by ultrasound was calculated from the area of the aortic orifice and the flow velocity just distal to the aortic cusps. The recordings were made twice at rest. Ten patients were given dobutamine (2.5 and 5.0 micrograms/kg/min) by infusion to induce rapid changes in stroke volume from the resting state. The individual Doppler ...

Ihlen, H.; Myhre, E.; Pamlie, J.; Forfang, K.; Larsen, S.

1985-01-01

191

A Human Gait Classification Method Based on Radar Doppler Spectrograms  

OpenAIRE

An image classification technique, which has recently been introduced for visual pattern recognition, is successfully applied for human gait classification based on radar Doppler signatures depicted in the time-frequency domain. The proposed method has three processing stages. The first two stages are designed to extract Doppler features that can effectively characterize human motion based on the nature of arm swings, and the third stage performs classification. Three types of arm motion are...

Fok Hing Chi Tivive; Abdesselam Bouzerdoum; Amin, Moeness G.

2010-01-01

192

Using doppler radar images to estimate aircraft navigational heading error  

Science.gov (United States)

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

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

2012-07-03

193

Resonant two photon spectrum in a doppler broadened line  

International Nuclear Information System (INIS)

The line shape in the resonant and near resonant two photon absorption spectra in the Na 3s1sub(/)2-3P1sub(/)2-5s1sub(/)2 transition was investigated using two single frequency dye lasers. Two types of Doppler-free peaks for resonant case and Doppler-broadened normal two photon peaks were observed. They were different in the width, selection rule and the laser power dependence in agreement with theory. (orig.)

194

Doppler broadening studies of surface-modified conducting polyethylene  

International Nuclear Information System (INIS)

Carbon doped, conducting polyethylene has been studied by positron techniques: bulk lifetime and depth-resolved doppler broadening analysis. Lowering of the Doppler broadening S-parameter has been observed for samples just at percolation threshold. Chemical modifications reduce diffusion of positrons in near surface layers. Doping with carbon does not change free-volumes, as monitored via long component of positron lifetime spectrum. (author). 7 refs, 3 figs

195

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

196

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

197

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

198

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-07-01

199

Smoke-Column Observations from Two Forest Fires Using Doppler Lidar and Doppler Radar.  

Science.gov (United States)

To demonstrate the usefulness of active remote-sensing systems in observing forest fire plume behavior, we studied two fires, one using a 3.2-cm-wavelength Doppler radar, and one more extensively, using Doppler lidar. Both instruments observed the kinematics of the convection column, including the presence of two different types of rotation in the columns, and monitored the behavior of the smoke plume.The first fire, a forest fire that burned out of control, was observed by the Doppler radar during late-morning and afternoon hours. Strong horizontal ambient winds produced a bent-over convection column, which the radar observed to have strong horizontal flow at its edges and weaker flow along the centerline of the plume. This velocity pattern implies that the column consisted of a pair of counterrotating horizontal vortices (rolls), with rising motion along the centerline and sinking along the edges. The radar tracked the smoke plume for over 30 km. It also provided circular depolarization ratio measurements, which gave information that the scattering particles were mostly flat or needle shaped as viewed by the radar, perhaps pine needles or possibly flat ash platelets being viewed edge on.The second fire, observed over a 5-h period by Doppler lidar, was a prescribed forest fire ignited in the afternoon. During the first hour of the fire the lidar observed many kinematic quantities of the convection column, including flow convergence and anticyclonic whole-column, rotation of the nearly vertical column, with a vorticity of approximately 102 s1 and an estimated peak vertical velocity w of 1 5 m s1. After the first hour ambient meteorological conditions changed, the whole-column rotation ceased, and the convection column and smoke plume bent over toward the lidar in stronger horizontal flow. At two times during this later stage, w was estimated to be 24 and 10 m s1. Lidar observations show that the smoke plume of this second fire initially went straight up in the convection column to heights of over 2 km, so most of the smoke was injected into the atmosphere above the unstable, afternoon, convective boundary layer, or mixed layer. Later, as the horizontal winds increased, a larger friction of the smoke remained in the mixed layer. Finally, very late in the afternoon, after ignitions had ceased and the fire was smoldering, almost all of the smoke remained within the mixed layer.These analyses show that lidar and radar can provide valuable three-dimensional datasets on kinematic quantities and smoke distribution in the vicinity of fires. This kind of information should be of great value in understanding and modeling convection-column dynamics and smoke-plume behavior.

Banta, R. M.; Olivier, L. D.; Holloway, E. T.; Kropfli, R. A.; Bartram, B. W.; Cupp, R. E.; Post, M. J.

1992-11-01

200

Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking  

Directory of Open Access Journals (Sweden)

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

Armstrong J. W.

2006-01-01

201

Analysis of Radar Doppler Signature from Human Data  

Directory of Open Access Journals (Sweden)

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

M. ANDRI?

2014-04-01

202

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

Science.gov (United States)

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

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

1986-01-01

203

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

LENUS (Irish Health Repository)

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

Kennelly, M M

2012-04-01

204

Doppler optical coherence tomography in cardiovascular applications  

Science.gov (United States)

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

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

2010-06-01

205

Doppler optical coherence tomography in cardiovascular physiology  

Science.gov (United States)

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

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

2008-09-01

206

DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS  

International Nuclear Information System (INIS)

The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation—and Doppler signature—of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows toward Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blueshifted and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps these waves and inhibits jet formation. As a result, this second regime exhibits a circulation dominated by high-altitude, day-to-night airflow, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art circulation models including non-gray radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that cool planets like GJ 436b lie in the first regime, HD 189733b b lie in the first regime, HD 189733b is transitional, while planets hotter than HD 209458b lie in the second regime. Moreover, we show how the amplitude of the Doppler shifts constrains the strength of frictional drag in the upper atmospheres of hot Jupiters. If due to winds, the ?2 km s–1 blueshift inferred on HD 209458b may require drag time constants as short as 104-106 s, possibly the result of Lorentz-force braking on this planet's hot dayside.

207

Comparison between oscillometric- and Doppler-ABI in elderly individuals  

Directory of Open Access Journals (Sweden)

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

Takahashi I

2013-03-01

208

[Technic of the peroperative use of Doppler in neurosurgery].  

Science.gov (United States)

Intraoperative Doppler exploration during neurosurgery was used during treatment of intracranial aneurysms, arteriovenous malformations (AVM) and cerebral revascularization by extra-intra cranial anastomosis (EICA). It was also employed to study behavior of cortical arteries under different conditions. During treatment of aneurysms, Doppler can show, prior to clipping, whether blood flow through. The flow is regular--spasm of supply artery provokes acceleration of blood rate. After clipping it is possible to evaluate whether artery is still permeable without stenosis or torsion. In AVM, Doppler detects direction of blood. Flow and, in case of intraoperative embolization, confirms good exclusion of angiomatous nidus. Flow rate in cortical arteries was determined to verify reality of operative trauma under automatic retractors used in standard surgery. In EICA, Doppler provides precise data on exact localization of cutaneous incision centered on superficial temporal artery (STA) (longitudinal incision) and identifies its parietal branch. The artery in the cortical vessels with the lowest flow rate can be selected. After EICA it is possible to identify whether the donor artery is under spasm from the proximal clamp and whether or not the anastomosis is patent. When functioning is correct it can be defined whether there exists a preferential direction or a regular laminar distribution in T. In tumoral pathology, Doppler serves to identify arteries enclosed in lesion and therefore whether conservation is essential. PMID:3294324

Fuentes, J M; Benezech, J; Cesari, J B; Vongsouthi, C; Prince, P; Billet, M

1988-01-01

209

Response of a Doppler canceling system to plane gravitational waves  

Science.gov (United States)

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

Caporali, A.

1982-01-01

210

Response of a Doppler canceling system to plane gravitational waves  

International Nuclear Information System (INIS)

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

211

Quantitative study of steady flow using color Doppler ultrasound.  

Science.gov (United States)

The use of color Doppler flow mapping systems for quantitative in vitro studies of flow fields is examined and illustrated. A 5-MHz color Doppler system was used, and the resolution was determined by comparing the results of flow-field measurement for steady parabolic pipe flow with calculated values. The velocity accuracy was about 6% of the velocity corresponding to half the pulse repetition frequency, and the spatial resolution was better than 1 mm. Frame frequency limitations permitted only partial tracking of fast temporal changes in the flow field. However, detection of vortices downstream from a small cylinder placed in the flow tube was significantly enhanced by synchronizing the frame frequency with the vortex shedding frequency and using a velocity-variance mode. Color Doppler aliasing was found to be useful to define streamlines and determine whether the flow was laminar or turbulent. The color Doppler system clearly imaged Poiseuille, transitional and turbulent flow and vortex shedding in vitro. It is concluded that color Doppler ultrasound flow mapping can enable large, complex flow fields to be quantitatively studied in vitro. PMID:1962362

Tamura, T; Cobbold, R S; Johnston, K W

1991-01-01

212

Long duration meteor echoes characterized by Doppler spectrum bifurcation  

Science.gov (United States)

We report on a new category of long lasting meteor echoes observed occasionally with HF and VHF radars. These meteoric returns, which have lifetimes from many seconds to a few minutes, are characterized by a distinct Doppler spectral signature showing a pronounced Doppler bifurcation which includes narrow bands of discrete Doppler velocities, often of opposite polarity. The large signal to noise ratios and the narrowness of the spectra imply that coherent or Bragg scattering is not of relevance here, therefore these echoes do not associate with the long living meteor-induced backscatter (MIB) from the lower E region. A reasonable interpretation needs to explain both the Doppler spectrum bifurcation and the long echo duration. As such, we propose the idea of a structured vertical wind shear in the lower E region which traps different fragments of a meteor trail plasma in the same way that sporadic E layers form. These trail parts inside the shear-related wind profile may act as relatively long-lasting meteoric reflectors moving with different Doppler velocities, also of opposite polarity.

Bourdillon, A.; Haldoupis, C.; Hanuise, C.; Le Roux, Y.; Menard, J.

2005-03-01

213

Doppler Uterine Artery Flow Velocimetry in Prediction of Preterm Labor  

Directory of Open Access Journals (Sweden)

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.  

Mahyar Mohammadi Fard

2009-01-01

214

Blood flow measurement by laser Doppler method in orofacial region  

Directory of Open Access Journals (Sweden)

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

Grga ?urica

2010-01-01

215

Cardiac tissue Doppler imaging in sports medicine.  

Science.gov (United States)

The differentiation of training-induced cardiac adaptations from pathological conditions is a key issue in sports cardiology. As morphological features do not allow for a clear delineation of early stages of relevant pathologies, the echocardiographic evaluation of left ventricular function is the technique of first choice in this regard. Tissue Doppler imaging (TDI) is a relatively recent method for the assessment of cardiac function that provides direct, local measurements of myocardial velocities throughout the cardiac cycle. Although it has shown a superior sensitivity in the detection of ventricular dysfunction in clinical and experimental studies, its application in sports medicine is still rare. Besides technical factors, this may be due to a lack in consensus on the characteristics of ventricular function in relevant conditions. For more than two decades there has been an ongoing debate on the existence of a supernormal left ventricular function in athlete's heart. While results from traditional echocardiography are conflicting, TDI studies established an improved diastolic function in endurance-trained athletes with athlete's heart compared with controls.The influence of anabolic steroids on cardiac function also has been investigated by standard echocardiographic techniques with inconsistent results. The only TDI study dealing with this topic demonstrated a significantly impaired diastolic function in bodybuilders with long-term abuse of anabolic steroids compared with strength-trained athletes without abuse of anabolic steroids and controls, respectively.Hypertrophic cardiomyopathy is the most frequent cause of sudden death in young athletes. However, in its early stages, it is difficult to distinguish from athlete's heart. By means of TDI, ventricular dysfunction in hypertrophic cardiomyopathy can be disclosed even before the development of left ventricular hypertrophy. Also, a differentiation of left ventricular hypertrophy due to hypertrophic cardiomyopathy or systemic hypertension is possible by TDI. Besides the evaluation of different forms of left ventricular hypertrophy, the diagnosis of myocarditis is also of particular importance in athletes. Today, it still requires myocardial biopsy. The analysis of focal disturbances in myocardial velocities might be a promising non-invasive method; however, systematic validation studies are lacking. An important future issue for the implementation of TDI into routine examination will be the standardisation of procedures and the establishment of significant reference values for the above-mentioned conditions. Innovative TDI parameters also merit further investigation. PMID:17190533

Krieg, Anne; Scharhag, Jürgen; Kindermann, Wilfried; Urhausen, Axel

2007-01-01

216

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

DEFF Research Database (Denmark)

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

Boesen, M I; Boesen, Mikael

2011-01-01

217

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

DEFF Research Database (Denmark)

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

Boesen, M I; Boesen, M

2010-01-01

218

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

Science.gov (United States)

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

Fung, Edward K.; Carson, Richard E.

2013-03-01

219

Three-dimensional laser cooling at the Doppler limit  

Science.gov (United States)

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.

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

2014-12-01

220

The implications of precise timekeeping of doppler gravitational wave observations  

International Nuclear Information System (INIS)

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

221

Imaging nanoparticle flow using magneto-motive optical Doppler tomography  

International Nuclear Information System (INIS)

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

222

Micro-range micro-doppler for dismount classification  

Science.gov (United States)

This paper presents a processing technique that can be used to detect and classify pedestrians group based on the micro- Doppler signature gathered with a millimeter wave radar. The evaluation of the number of pedestrians moving in a group can be a difficult task using a traditional micro-Doppler spectrogram because of a tendency for people to partially synchronize their steps when walking together. The new approach, based on multi-range variation as well as the micro-Doppler variations, provides promising results. The range-spectrogram processing technique was developed and tested using a database composed of hundreds of pedestrian and vehicle signatures gathered in an urban test site over a two year period in a variety of weather conditions. We associate image detections with radar detections through motion extracted from both radar and imagery. We also explain how radar and video together can produce an inexpensive alternative to 3-D imaging.

Tahmoush, Dave

2013-05-01

223

An introduction and guide to effective Doppler assessment.  

Science.gov (United States)

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

Benbow, Maureen

2014-12-01

224

Characterization of vortices using pulsed-wave Doppler ultrasound.  

Science.gov (United States)

The detection and characterization of vortices from a Kaman vortex generator by means of a 20 MHz pulsed-wave Doppler ultrasound system were assessed. Measurements were made at different steady flowrates in a 10 mm internal diameter polyurethane tube, 14 mm distal to a circular cylinder of diameter 2 mm, placed across the tube inlet. The results were compared with those obtained with a two-component laser Doppler anemometer system. There was generally good agreement between the two techniques in the measurement of convective flow velocity, frequency of vortex shedding and the circulation velocity of the vortices. It is concluded that pulsed-wave Doppler ultrasound is a suitable technique for investigating vortical flow structures. PMID:11201415

Gaupp, S; Wang, Y; How, T V; Fish, P J

2000-01-01

225

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)

226

Three-dimensional laser cooling at the Doppler limit  

CERN Document Server

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

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

2014-01-01

227

The Doppler paradigm and the APEX-EPOS-ORANGE quandary  

CERN Document Server

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

Griffin, J J

1996-01-01

228

A Human Gait Classification Method Based on Radar Doppler Spectrograms  

Directory of Open Access Journals (Sweden)

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

Fok Hing Chi Tivive

2010-01-01

229

Spacecraft-Doppler gravity-wave detection. I. Theory  

International Nuclear Information System (INIS)

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

230

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

231

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

Science.gov (United States)

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

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

2004-07-01

232

Holographic laser Doppler imaging of microvascular blood flow  

CERN Document Server

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

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

2014-01-01

233

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

Science.gov (United States)

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

Browne, Jacinta E

2014-11-01

234

New measurement of the relativistic Doppler shift in neon  

International Nuclear Information System (INIS)

The Doppler free two photon transition from the metastable 1S5 to 4S1'double-prime in neon was measured for both a fast beam (?120 keV) and a slow thermal beam. The transition frequencies for each beam were measured independently relative to a hyperfine component of a nearby I2 reference line. The absolute frequency shift between the two beams was obtained. This measurement of the relativistic Doppler shift verifies the time dilation effect to an accuracy of 2.3 ppm which represents a more than 10 fold improvement over previous measurements

235

Cerebral infarction following a carotid Doppler ultrasound: a chance association?  

Science.gov (United States)

The authors present a case report of a 64-year-old lady with multiple risk factors for atherosclerosis, who suffered an ischaemic stroke immediately following carotid Doppler ultrasound despite therapeutic warfarin and antiplatelet therapy. This event was only 16 days after the patient suffered a first ischaemic stroke during diagnostic coronary angiography following a syncopal episode accompanied with a raised troponin-T. The temporal relationship between the carotid Doppler ultrasound and second ischaemic stroke raised the question whether it was possible that the investigation had caused the stroke, a complication not previously recognised. PMID:22892233

Roberton, Andrew; Shinton, Roger; Clow, Laura; Tudway, David

2012-01-01

236

Fano-Doppler laser cooling of hybrid nanostructures.  

Science.gov (United States)

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

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

2011-09-27

237

Optical Doppler tomography based on a field programmable gate array  

DEFF Research Database (Denmark)

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

Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup

2008-01-01

238

Feasibility assessment of Doppler radar long-term physiological measurements.  

Science.gov (United States)

In this paper we examine the feasibility of applying doppler radar technique for a long-term health monitoring. Doppler radar was used to detect and eliminate periods of significant motion. This technique was verified using a human study on 17 subjects, and it was determined that for 15 out of 17 subjects there was no significant motion for over 85% of the measurement interval in supine positions. Majority of subjects exhibited significantly less motion in supine position, which is promising for sleep monitoring, and monitoring of hospitalized patients. PMID:22254615

Massagram, Wansuree; Lubecke, Victor M; Boric-Lubecke, Olga

2011-01-01

239

ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO  

Directory of Open Access Journals (Sweden)

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

Marcelo Rodríguez G

2010-01-01

240

ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO  

Scientific Electronic Library Online (English)

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

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

241

Classification of the subclavian steal syndrome with transcranial Doppler.  

Science.gov (United States)

Ultrasound has provided a highlight of the different types of subclavian steal. The authors report epidemiological and clinical data concerning 40,000 ultrasound examinations performed on epiaortic arteries and particularly the last 12,000 in which Doppler c.w., duplex scanner and transcranial Doppler were used. Various types of steal are described; five types of subclavian steal have been classified and patients stratified as being symptomatic and asymptomatic. The neurological symptoms are divided as follows: generalized cerebral ischemia, vertebro-basilar ischemia and hemispheric ischemia. Based on this clinical and haemodynamic outline, surgical therapy is indicated and type of surgery suggested. PMID:9201124

Berni, A; Tromba, L; Cavaiola, S; Tombesi, T; Castellani, L

1997-04-01

242

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)

243

Spectral fine structure effects on material and doppler reactivity worth  

International Nuclear Information System (INIS)

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

244

Development of Doppler Sodar for environmental monitoring- salient design features  

International Nuclear Information System (INIS)

Doppler Sodar is one of the most sophisticated instruments used for assessment of environmental impacts due to nuclear and thermal power plants. The transport and dispersion of hazardous pollutants released in the air is mainly governed by meteorological factors like temperatures and winds which vary with space and time. This paper presents salient design features of Doppler Sodar capable of giving continuous unattended measurements of wind speeds, wind directions and thermal structures up to 1000 meter with resolution of about 30 meters. Representative results obtained from its operation are very encouraging. 2 refs., 3 figs

245

Color Doppler imaging of early arterial bypass graft dysfunction  

International Nuclear Information System (INIS)

This paper reports prospective comparison of color Doppler US and arteriography performed in 14 patients who had undergone arterial revascularization with venous grafts. Color Doppler was used to locate the site of stenosis, and duplex US with spectrum analysis was used to measure peak systolic velocities. Arteriograms were compared with US findings on a segment-by-segment basis. A velocity >1.3 m/sec was used as a discriminator; sensitivity was 84% (16 of 19) and specificity was 100% (73 of 73) for detecting lesions >50% lumen diameter narrowing. The authors conclude that color-assisted duplex imaging is an accurate means of detecting stenoses in venous arterial bypass grafts

246

Color Doppler imaging of cardiac catheters using vibrating motors.  

Science.gov (United States)

A miniature motor rotating at 11,000 rpm was attached onto the proximal end of cardiac electrophysiological (EP) catheters in order to produce vibrations at the tip that were then visualized by color Doppler on ultrasound scanners. The catheter tip was imaged 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 visualized in each case, although results varied with the color Doppler properties of the individual scanner. PMID:19514134

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

2008-10-01

247

Determination of Doppler Effect on nuclear resonances of uranium-238  

International Nuclear Information System (INIS)

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

248

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

249

Real-time bulk-motion-correction free Doppler variance optical coherence tomography for choroidal capillary vasculature imaging  

OpenAIRE

In this paper, we analyze the retinal and choroidal blood vasculature in the posterior segment of the human eye with optimized color Doppler and Doppler variance optical coherence tomography. Depth-resolved structure, color Doppler and Doppler variance images are compared. Blood vessels down to the capillary level were detected and visualized with the optimized optical coherence color Doppler and Doppler variance method. For in-vivo imaging of human eyes, bulk-motion induced bulk phase must b...

Liu, Gangjun; Qi, Wenjuan; Yu, Lingfeng; Chen, Zhongping

2011-01-01

250

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

Directory of Open Access Journals (Sweden)

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

Claudio E Scherle-Matamoros

2011-03-01

251

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

Scientific Electronic Library Online (English)

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

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

2011-03-01

252

A simplified study of trans-mitral Doppler patterns  

Directory of Open Access Journals (Sweden)

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.

Thomas George

2008-11-01

253

Usefulness of Doppler Parameter in Patients with Renal Transplantation  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-08-15

254

Analysis of multiple scattering effects in optical Doppler tomography  

DEFF Research Database (Denmark)

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

Yura, H.T.; Thrane, L.

2005-01-01

255

Cosmic Background Radiation Temperature Anisotropy Position of First Doppler Peak  

CERN Document Server

The purpose of the Cosmic Background Radiation (CBR) experiments is to measure the temperature anisotropy via the autocorrelation function. The partial wave $l_1$ corresponding to the first Doppler peak caused by baryon-photon oscillations at the surface of last scattering depends on the present density $\\Omega_0$ and the cosmological constant contribution figures.

Frampton, Paul H; Rohm, R M; Frampton, Paul H.; Rohm, Ryan

1998-01-01

256

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.

257

Doppler measurement integration for kinematic real-time GPS positioning  

OpenAIRE

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

Agostino, Mattia; Manzino, Ambrogio

2010-01-01

258

Relativistic Doppler effect in a uniformly accelerated motion - III  

CERN Document Server

In the context of special relativity, we describe with detail the Doppler effect between a light source at rest and an observer in linear motion and constant proper acceleration. To have an Englis version of this article, ask the authors. ----- ^Ce special-relativeco ni detale priskribas lum-Doppleran efikon inter restanta fonto kaj observanto kun rektilinia movado kaj konstanta propra akcelo.

Paiva, F M

2008-01-01

259

High-Energy 2-Micrometers Doppler Lidar for Wind Measurements  

Science.gov (United States)

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

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

2006-01-01

260

Doppler sonography in diagnosis of the acute scrotum  

Directory of Open Access Journals (Sweden)

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

Nikoli? Olivera

2006-01-01

261

Color Doppler in the Assessment of Uteroplacental Circulation Insufficiency  

Directory of Open Access Journals (Sweden)

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

Ahmad Soltani Shirazi

2010-05-01

262

Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-05-04

263

Complex Doppler effect in left-handed metamaterials  

CERN Document Server

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.

Ziemkiewicz, David

2014-01-01

264

Complex Doppler effect in left-handed metamaterials  

Science.gov (United States)

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.

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

2015-03-01

265

Viking S-band Doppler RMS phase fluctuations used to calibrate the mean 1976 equatorial corona  

Science.gov (United States)

Viking S-band Doppler RMS phase fluctuations (noise) and comparisons of Viking Doppler noise to Viking differenced S-X range measurements are used to construct a mean equatorial electron density model for 1976. Using Pioneer Doppler noise results (at high heliographic latitudes, also from 1976), an equivalent nonequatorial electron density model is approximated.

Berman, A. L.; Wackley, J. A.

1977-01-01

266

Color Doppler Ultrasonography in Evaluation of the Postoperative Penis  

Directory of Open Access Journals (Sweden)

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

M. Ghafouri

2005-08-01

267

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

Scientific Electronic Library Online (English)

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

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

1144-11-01

268

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-01-01

269

Non-Gaussianity and CMB aberration and Doppler  

Energy Technology Data Exchange (ETDEWEB)

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.

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

270

Doppler ultrasound scan during normal gestation: umbilical circulation  

International Nuclear Information System (INIS)

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

271

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

272

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

Scientific Electronic Library Online (English)

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.

Pablo Andrés, Victoria-Gómez.

2006-09-01

273

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

Directory of Open Access Journals (Sweden)

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

Pablo Andrés Victoria-Gómez

2006-09-01

274

All semiconductor laser Doppler anemometer at 1.55 ?m  

DEFF Research Database (Denmark)

We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz. Udgivelsesdato: October 23, 2008

Hansen, René Skov; Pedersen, Christian

2008-01-01

275

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

276

Analysis on wind retrieval methods for Rayleigh Doppler lidar  

Science.gov (United States)

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

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

2014-06-01

277

Gravimetric missions by VLBI and Doppler in SELENE  

Science.gov (United States)

SELENE is a mission in preparation for launch in 2007 by JAXA (Japan Aerospace Exploration Agency). It execute 15 experiments, two of which (RSAT and VRAD) are gravimetric experiments using radio waves. RSAT (Relay Satellite Transponder) mission will undertake 4-way Doppler measurements of the main orbiter through the Rstar sub-satellite. This is in addition to 2-way Doppler and ranging measurements of the satellites and will realize the first direct observation of the gravity fields on the far side of the Moon. VRAD (Differential VLBI Radio Source) mission involves observing the trajectories of Rstar and Vstar sub-satellites using differential VLBI with both a Japanese network (VERA), and an international network. We have already finished development of the onboard instruments and are carrying out proto-flight tests under various conditions. We have also performed test VLBI observations of orbiters with the international network.

Hanada, H.; Iwata, T.; Namiki, N.; Kawano, N.; Asari, K.; Ishikawa, T.; Kikuchi, F.; Liu, Q.; Matsumoto, K.; Noda, H.; Tsuruta, S.

2005-12-01

278

Multipoint photonic doppler velocimetry using optical lens elements  

Science.gov (United States)

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

Frogget, Brent Copely; Romero, Vincent Todd

2014-04-29

279

Doppler reflectometry for the investigation of poloidally propagating density perturbations  

International Nuclear Information System (INIS)

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

280

Doppler radar fall activity detection using the wavelet transform.  

Science.gov (United States)

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

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

2015-03-01

281

Gravity theories, Transverse Doppler and Gravitational Redshifts in Galaxy Clusters  

CERN Document Server

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.

Zhao, Hongsheng; Li, Baojiu

2012-01-01

282

Microwave Doppler reflectometer system in the Experimental Advanced Superconducting Tokamak.  

Science.gov (United States)

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

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

2013-10-01

283

SIGACE, Code for Doppler broadening of ACE-formatted files  

International Nuclear Information System (INIS)

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

284

Using Doppler Shifts of GPS Signals To Measure Angular Speed  

Science.gov (United States)

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

Campbell, Charles E., Jr.

2006-01-01

285

Multipath-dominant, pulsed doppler analysis of rotating blades  

CERN Document Server

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

Robinson, Michael

2012-01-01

286

Michelson interferometer null may confirm transverse Doppler Effect  

CERN Document Server

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

Woodruff, Robert A

2014-01-01

287

Reactive Collision Avoidance for Unmanned Aerial Vehicles using Doppler Radar  

OpenAIRE

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

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

2007-01-01

288

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

OpenAIRE

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

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

1989-01-01

289

Evaluation of the MV (CAPON) Coherent Doppler Lidar Velocity Estimator  

Science.gov (United States)

The performance of the CAPON velocity estimator for coherent Doppler lidar is determined for typical space-based and ground-based parameter regimes. Optimal input parameters for the algorithm were determined for each regime. For weak signals, performance is described by the standard deviation of the good estimates and the fraction of outliers. For strong signals, the fraction of outliers is zero. Numerical effort was also determined.

Lottman, B.; Frehlich, R.

1997-01-01

290

Laser Doppler flowmetry to measure changes in cerebral blood flow.  

OpenAIRE

Laser Doppler flowmetry (LDF) is a method by which relative cerebral blood flow (CBF) of the cortex can be measured. Although the method is easy to employ, LDF only measures relative CBF, while absolute CBF cannot be quantified. LDF is useful for investigating CBF changes in a number of different applications including neurovascular and stroke research. This chapter will prepare the reader for rodent experiments using LDF with two preparations. The closed skull preparation can be used to moni...

Sutherland, Ba; Rabie, T.; Buchan, Am

2014-01-01

291

Exploring shot noise and Laser Doppler imagery with heterodyne holography  

OpenAIRE

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.

Gross, Michel; Verpillat, Fre?de?ric; Joud, Fadwa; Atlan, Michael

2012-01-01

292

Analysis of energy-dependent Doppler experiment for uranium-238  

International Nuclear Information System (INIS)

The energy dependent Doppler effect for 238U was calculated using the collision probability method with the resonance parameters of the HRG library, and this calculated result was compared with the experiment carried out at Karlsruhe. Though the discrepancy between the calculation and the experiment is 1 -- 4%, the calculated result shows rather good agreement with the experiment in the energy region of 150 -- 1,000 eV, considering the experimental errors of 3.2%, except two experimental data. (auth.)

293

Graphical Representation of the Doppler Shift: Classical and Relativistic  

Science.gov (United States)

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

Rojas, R.; Fuster, G.

2007-01-01

294

Vocal fold vibration measurements using laser Doppler vibrometry  

OpenAIRE

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...

Chan, Alfred; Mongeau, Luc; Kost, Karen

2013-01-01

295

Detection of gravitational radiation by the Doppler tracking of spacecraft  

International Nuclear Information System (INIS)

It has been suggested that the residual Doppler shift in the precision electromagnetic tracking of spacecraft be used to search for gravitational radiation that may be incident on the Earth-spacecraft system. The influence of a gravitational wave on the Doppler shift is calculated, and it is found that the residual shift is dominated by two terms: one is due to the passage of electromagnetic waves through the gravitational radiation field, and the other depends on the change in the relative velocity of the Earth and the spacecraft caused by the external wave. A detailed analysis is given of the influence of gravitational radiation on a binary system with an orbital size small compared to the wavelength of the incident radiation. It is shown that, as a consequence of the interaction with the external wave, the system makes a transition from one Keplerian orbit into another which, in general, has a different energy and angular momentum. It is therefore proposed to search for such effects in the solar system. Observations of the orbit of an artificial Earth satellite, the lunar orbit, and especially the planetary orbits offer exciting possibilities for the detection of gravitational waves of various wavelengths. From the results of the lunar laser ranging experiment and the range measurement to Mars, certain interesting limits may be established on the frequency of incidence of gravitational waves of a given flux on the Earth-Moon and the Earth-Mars systems. This is folln and the Earth-Mars systems. This is followed by a brief and preliminary analysis of the possibility of detecting gravitational radiation by measuring a residual secular Doppler shift in the satellite-to-satellite Doppler tracking of two counterorbiting drag-free spacecraft around the Earth as in the Van Patten-Everitt experiment

296

MRI and colour-Doppler in sclerosing mesenteritis  

Energy Technology Data Exchange (ETDEWEB)

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

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

1992-08-01

297

MRI and colour-Doppler in sclerosing mesenteritis  

International Nuclear Information System (INIS)

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

298

A Fisheye Lens as a Photonic Doppler Velocimetry Probe  

Energy Technology Data Exchange (ETDEWEB)

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

Frogget, B. C.

2012-08-16

299

Wind Measurements with High Energy 2 Micron Coherent Doppler Lidar  

Science.gov (United States)

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

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

2004-01-01

300

Adaptive cancellation of harmonic interferences in transcranial Doppler signal  

Science.gov (United States)

This paper presents a method of improving the Transcranial Doppler (TCD) signal by removing harmonic interferences. Such interferences, originating from medical equipment using the high power HF signals are common in a clinical environment, especially in the neighborhood of the operating theater. The Adaptive Interference Canceler based on the NLMS FIR filter has been used. The reference signal was obtained by delaying of the original TCD signal. The presented method allows significant improvement of a seriously disturbed TCD signal.

Zabolotny, Wojciech M.; Karlowicz, Pawel; Jurkiewicz, Jerzy

2004-07-01

301

Doppler Effect of Nonlinear Waves and Superspirals in Oscillatory Media  

OpenAIRE

Nonlinear waves emitted from a moving source are studied. A meandering spiral in a reaction-diffusion medium provides an example, where waves originate from a source exhibiting a back-and-forth movement in radial direction. The periodic motion of the source induces a Doppler effect that causes a modulation in wavelength and amplitude of the waves (``superspiral''). Using the complex Ginzburg-Landau equation, we show that waves subject to a convective Eckhaus instability can ...

Brusch, Lutz; Torcini, Alessandro; Baer, Markus

2003-01-01

302

Detection of small UAV helicopters using micro-Doppler  

Science.gov (United States)

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

Tahmoush, David

2014-05-01

303

HF Bistatic Ocean Doppler Spectra: Simulation Versus Experimentation  

OpenAIRE

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

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

2013-01-01

304

Novel data evaluation algorithm for Coincident Doppler Broadening Spectroscopy  

Science.gov (United States)

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

Pikart, Philip; Hugenschmidt, Christoph

2014-06-01

305

Fluorescence during Doppler cooling of a single trapped atom  

OpenAIRE

We investigate the temporal dynamics of Doppler cooling of an initially hot single trapped atom in the weak binding regime using a semiclassical approach. We develop an analytical model for the simplest case of a single vibrational mode for a harmonic trap, and show how this model allows us to estimate the initial energy of the trapped particle by observing the fluorescence rate during the cooling process. The experimental implementation of this temperature measurement provi...

Wesenberg, J. H.; Epstein, R. J.; Leibfried, D.; Blakestad, R. B.; Britton, J.; Home, J. P.; Itano, W. M.; Jost, J. D.; Knill, E.; Langer, C.; Ozeri, R.; Seidelin, S.; Wineland, D. J.

2007-01-01

306

Transcranial Doppler Monitoring During Carotid Endarterectomy: A Technical Case Report  

OpenAIRE

We report a case involving a patient undergoing carotid endarterectomy in whom transcranial doppler monitoring demonstrated impaired cerebral blood flow during the initial dissection of the carotid artery, during cross-clamping of the carotid artery, and after the shunt was kinked inadvertently. Only when the carotid artery was cross-clamped were these ischemic changes also seen by electroencephalography. During the other episodes, the electroencephalography tracings demonstrated no detectabl...

Heyer, Eric J.; Winfree, Christopher J.; Mack, William J.; Connolly, E. Sander

2000-01-01

307

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.

308

Doppler broadening of neutron elastic scattering kernel in TRIPOLI-4®  

International Nuclear Information System (INIS)

Highlights: ? DBRC and WCM algorithms are implemented in TRIPOLI-4. ? The effects of resonant Doppler broadening on static and burnup criticality calculations is analyzed. ? The differential contributions of distinct isotopes are singled out. - Abstract: Recent works have pointed out some relevant shortcomings of the so called ‘Sampling of the Velocity of the Target nucleus’ (SVT) algorithm, which is currently used in most Monte Carlo codes for the Doppler broadening of the elastic scattering kernel. To overcome these limitations, which affect resonant nuclei such as 238U, and whose consequences in pincell criticality calculations can amount to a drop of several hundred pcm, the Doppler Broadening Rejection Correction (DBRC) and the Weight Correction Method (WCM) have been proposed. In this work, we illustrate the implementation of DBRC and WCM in the TRIPOLI-4® Monte Carlo code. Several validation tests are discussed, and the impact of using DBRC or WMC to replace SVT is analyzed in detail in static as well as burnup calculations for UOX and MOX pincells, and in a PWR full-core simulation

309

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

310

Gestational trophoblastic neoplasia: efficacy of color doppler ultrasound  

International Nuclear Information System (INIS)

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

311

Doppler radar wind field retrieval over the Po Valley  

Directory of Open Access Journals (Sweden)

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

Y. K. Goh

2006-01-01

312

Reducing Spaceborne-Doppler-Radar Rainfall-Velocity Error  

Science.gov (United States)

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.

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

2008-01-01

313

Carotid artery Doppler ultrasonography in patients with chronic kidney disease  

Science.gov (United States)

Background We investigated the changes in the values of carotid intima-media thickness (IMT) and Doppler index measurements in the autosomal dominant polycystic kidney disease (ADPKD), peritoneal dialysis (PD), and hemodialysis (HD) patients. Material/Methods Twenty outpatients on HD (mean age 46.1±16.4), 27 outpatients on PD (mean age 45±12.4), and 26 normotensive outpatients with ADPKD (mean age 52.4±16.7) as the case groups and 21 healthy subjects (mean age 48.4±7.2), as the control group, were included. The participants underwent ultrasonography of the common, right, and left carotid arteries for the IMT and Doppler flow measurements. Results Overall, compared to the normal group, in the study groups, the IMT and peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) were significantly higher in common carotid arteries; however, their differences were not meaningful in internal carotid arteries (p<0.05). Conclusions Overall, ADPKD, PD, and HD increase the IMT, PSV, EDV, RI, and PI values of CCA; however, their effect considerable less on the study parameters of ICA. There is no considerable difference among the effects of ADPKD, HD, and PD on the study parameters. Of CKD patients during the first diagnostic and follow-up workups, the measurements of carotid IMT and Doppler indices may provide valuable data for improving success of the clinical management. PMID:24394695

Salk, Ismail; Yildiz, Gursel; Egilmez, Hulusi; Atalar, Mehmet Haydar; Candan, Ferhan; Cetin, Ali

2014-01-01

314

Advances in precision Doppler spectroscopy on cool stars  

Directory of Open Access Journals (Sweden)

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

Anglada-Escudé Guillem

2013-04-01

315

Dual-illumination planar Doppler velocimetry using a single camera  

Science.gov (United States)

A Planar Doppler Velocimetry (PDV) illumination system has been designed which is able to generate two beams, separated in frequency by about 600 MHz. This allows a common-path imaging head to be constructed, using a single imaging camera instead of the usual camera pair. Both illumination beams can be derived from a single laser, using acousto-optic modulators to effect the frequency shifts. One illumination frequency lies on an absorption line of gaseous iodine, and the other just off the absorption line. The beams sequentially illuminate a plane within a seeded flow and Doppler-shifted scattered light passes through an iodine vapor cell onto the camera. The beam that lies at an optical frequency away from the absorption line is not affected by passage through the cell, and provides a reference image. The other beam, the frequency of which coincides with an absorption line, encodes the velocity information as a variation in transmission dependent upon the Doppler shift. Images of the flow under both illumination frequencies are formed on the same camera, ensuring registration of the reference and signal images. This removes a major problem of a two-camera imaging head, and cost efficiency is also improved by the simplification of the system. The dual illumination technique has been shown to operate successfully with a spinning disc as a test object. The benefits of combining the dual illumination system with a three-component, fiber-linked imaging head developed at Cranfield will be discussed.

Charrett, Tom O. H.; Ford, Helen D.; Nobes, David S.; Tatam, Ralph P.

2003-11-01

316

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

OpenAIRE

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

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

2013-01-01

317

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

Scientific Electronic Library Online (English)

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 [...

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.

1931-19-01

318

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)

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.

Emmanuelle Tenório Albuquerque Madruga Godoi

2008-04-01

319

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

Scientific Electronic Library Online (English)

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

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

2008-04-01

320

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)

321

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-06-01

322

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

Scientific Electronic Library Online (English)

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

José Alexandre, Mendonça.

2014-12-01

323

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

OpenAIRE

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...

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

2002-01-01

324

Intrinsic Lorentz violation in Doppler effect from a moving point light source  

OpenAIRE

Einstein's Doppler formula is not applicable when a moving point light source is close enough to the observer; for example, it may break down or cannot specify a determinate value when the point source and the observer overlap. In this paper, Doppler effect for a moving point light source is analyzed, and it is found that the principle of relativity allows the existence of intrinsic Lorentz violation. A conceptual scheme to experimentally test the point-source Doppler effect...

Wang, Changbiao

2010-01-01

325

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

OpenAIRE

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

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

2010-01-01

326

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

OpenAIRE

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

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

2010-01-01

327

Micro-Doppler Frequency Estimation Based on Radon-Wigner Transform  

Directory of Open Access Journals (Sweden)

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

Sun Huixia

2014-01-01

328

Doppler Radar Speed Measurement Based On A 24 GHz Radar Sensor  

OpenAIRE

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

Dybedal, Joacim

2013-01-01

329

A New Underwater Acoustic Navigation Method Based on the Doppler Principle  

Directory of Open Access Journals (Sweden)

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

Jinsong Tang

2013-07-01

330

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

International Nuclear Information System (INIS)

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

331

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

Science.gov (United States)

The development of a field-programmable gate array (FPGA)-based pulsed-wave Doppler processing approach in pure digital domain is reported in this paper. After the ultrasound signals are digitized, directional Doppler frequency shifts are obtained with a digital-down converter followed by a low-pass filter. A Doppler spectrum is then calculated using the complex fast Fourier transform core inside the FPGA. In this approach, a pulsed-wave Doppler implementation core with reconfigurable and real-time processing capability is achieved. PMID:18986909

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

2009-01-01

332

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

Directory of Open Access Journals (Sweden)

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.

Alkan Alpay

2002-02-01

333

Non-Doppler Redshift and Dark Matter in the Coma Cluster  

OpenAIRE

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

Zheng, Yi-jia

2013-01-01

334

Generation of void and Doppler reactivity feedback for application to BWR design (amendment No. 1)  

International Nuclear Information System (INIS)

Information is presented under the following section headings: (1) Doppler reactivity and reactivity coefficients, (2) void reactivity and reactivity coefficients, and (3) design philosophy for plant transient analysis

335

Doppler ultrasonography: A tool for nephrologists - single centre experience  

International Nuclear Information System (INIS)

Colour Doppler duplex ultrasonography (CDUS) has allowed noninvasive assessment of alternations of vascular perfusion showing general perfusion in colour. Since 1996, ultrasound examination by a duplex Doppler apparatus has been performed with an HDI 3000, ATL machine.We have retrospectively evaluated all patients (pts) with colour Doppler duplex examination for the last tree years. Resistive indexes (RIs) are measured in each kidney using the existing software capabilities of the scanner. A total of 2581 CDUS examinations were performed over the past three years; in 2005 - 883 pts, in 2006 - 908 pts and on 2007 - 790 pts. Most of these examinations were an transplant pts. In 98 cases we examinated chronic rejection reactions, in 58 cases acute rejection and in 38 cases we postulated renal artery stenosis or thrombosis. We used CDUS to determine whether the RI can be used as a predictor in pts with Diabetic Nephropathy; in 108 cases we found an increased RI>0.68. there is a positive correlation between the RI and the severity of arteriolosclerosis in the majority of pts, 331, where we found nephroarterioloslerosis (RI>0.64). In 52 cases renal artery stenosis was suspected (0.04 differences between RI on right and left renal artery). Acute renal failure was suspected in 53 cases. According to neoplasms, pathological, marked increased vascularisation was noticed in 34 cases suspected for renal carcinoma, in 46 cases suspected of testicular tumours, 19 cases suspected of testicular tumours, 19 cases suspected of prostate neoplasm and 32 cases suspected of tumours in other localization. In combination with patient history, clinical and laboratory examination CDUS provides very useful information in accomplishing the diagnosis.

336

Investigation of Frequency Analysis Methods for Doppler Ultrasound Systems  

Directory of Open Access Journals (Sweden)

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.

Tatsuro Baba

2013-03-01

337

PRECISE DOPPLER MONITORING OF BARNARD'S STAR  

Energy Technology Data Exchange (ETDEWEB)

We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during the 25 years between 1987 and 2012. The early precision was 20 m s{sup -1} but was 2 m s{sup -1} during the last 8 years, constituting the most extensive and sensitive search for Doppler signatures of planets around this stellar neighbor. We carefully analyze the 136 Keck radial velocities spanning 8 years by first applying a periodogram analysis to search for nearly circular orbits. We find no significant periodic Doppler signals with amplitudes above {approx}2 m s{sup -1}, setting firm upper limits on the minimum mass (Msin i) of any planets with orbital periods from 0.1 to 1000 days. Using a Monte Carlo analysis for circular orbits, we determine that planetary companions to Barnard's Star with masses above 2 M {sub Circled-Plus} and periods below 10 days would have been detected. Planets with periods up to 2 years and masses above 10 M {sub Circled-Plus} (0.03 M {sub Jup}) are also ruled out. A similar analysis allowing for eccentric orbits yields comparable mass limits. The habitable zone of Barnard's Star appears to be devoid of roughly Earth-mass planets or larger, save for face-on orbits. Previous claims of planets around the star by van de Kamp are strongly refuted. The radial velocity of Barnard's Star increases with time at 4.515 {+-} 0.002 m s{sup -1} yr{sup -1}, consistent with the predicted geometrical effect, secular acceleration, that exchanges transverse for radial components of velocity.

Choi, Jieun; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); McCarthy, Chris [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States); Fischer, Debra A. [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Johnson, John A. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Wright, Jason T., E-mail: jieun_eb@berkeley.edu [Department of Astronomy, The Pennsylvania State University, University Park, PA 16802 (United States)

2013-02-20

338

[Ultrasound and color Doppler in nephrology. Technology and applications].  

Science.gov (United States)

Advances in digital technology in the last decades have led to a fast development of ultrasound technology. Ultrasound information originating from stationary structures or red blood cells moving into the vessels can be visualized with different imaging modalities. Conventional B-mode sonography provides anatomical details based on acoustic impedance differences. Gray-scale sonography represents the structural echoes as brightness points. Based on the Doppler effect, vascular scattering can be represented as spectral wave velocity depending on time (velocity/time curve), or as dual-scale color mapping depending on the changes in average blood velocity. The flow-in is depicted in red and the flow-out in blue. The analysis of the vascular scattering enhanced by infusion of contrast agents is the basis of contrast-enhanced harmonic imaging. The perfusional pattern of tissues allows the differential diagnosis of expansive lesions. Tissue strain analysis provides a new dimension of diagnostic information. It is used in elastographic imaging to describe relative physical tissue stiffness properties. Tissue stiffness information is complementary to and independent of the acoustic impedance information provided by B-mode imaging as well as the vascular flow information provided by Doppler imaging. Adjacent tissue elements may appear identical using conventional B-mode or Doppler imaging. When stress (axial force) is applied to tissues, they show different degrees of deformation. Comparing the baseline and stress image information, each tissue element may be labeled by its relative stiffness. A lighter shade indicates relatively soft tissue (elastic), while a darker shade indicates relatively stiff tissue (non-elastic). PMID:22538950

Meola, Mario; Petrucci, Ilaria; Bortolotto, Chandra; Carone, Luisa

2012-01-01

339

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

International Nuclear Information System (INIS)

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 tesient 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

340

Observing crosswind over urban terrain using scintillometer and Doppler lidar  

Science.gov (United States)

In this study, the crosswind (wind component perpendicular to a path, U\\bot) 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\\bot (U\\bot), while the Doppler lidar allows acquisition of path-resolved U\\bot (U\\bot (x), where x is the position along the path). The goal of this study is to evaluate the applicability of scintillometer U\\bot-measurements for conditions where U\\bot (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\\bot 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\\bot 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\\bot (x) than the lookup table method. However, the lookup table method can be adjusted to improve its capabilities to obtain U\\bot for conditions where U\\bot (x) is variable.

van Dinther, D.; Wood, C. R.; Hartogensis, O. K.; Nordbo, A.; O'Connor, E. J.

2014-07-01

341

Observing crosswind over urban terrain using scintillometer and Doppler lidar  

Directory of Open Access Journals (Sweden)

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.

D. van Dinther

2014-07-01

342

Coherent Doppler Laser Radar: Technology Development and Applications  

Science.gov (United States)

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.

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

2000-01-01

343

Global Doppler frequency shift detection with near-resonant interferometry  

Science.gov (United States)

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.

Landolt, Andrin; Roesgen, Thomas

2009-10-01

344

Doppler prediction of adverse perinatal outcome in intrauterine growth restriction  

Directory of Open Access Journals (Sweden)

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

Nina Mahale

2015-02-01

345

Doppler cooling of an optically dense cloud of trapped atoms  

CERN Document Server

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.

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

346

Sub-Doppler Laser Cooling of Fermionic K-40 Atoms  

CERN Document Server

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.

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

1999-01-01

347

Observations of Oklahoma severe thunderstorms using airborne Doppler lidar  

Science.gov (United States)

The NASA airborne Doppler lidar was successfully employed in obtaining detailed views of the horizontal wind fields near a complex of severe multicell thunderstorms in central Oklahoma on June 30, 1981. Despite uncertainties caused by inertial navigation errors, clear pictures of the relative reflectivity distributions, horizontal wind velocity, and velocity spectral width near the cloud base were obtained. The presence of numerous gust front vortices along the leading edge of the advancing storm outflow were noted which correspond to inflections in the shape of the gust front arcus cloud formation. Explanations for the observed vortical circulations and calculated vorticities are given.

Mccaul, E. W., Jr.; Bluestein, Howard B.; Doviak, Richard J.

1985-01-01

348

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

Energy Technology Data Exchange (ETDEWEB)

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.

Dolan, Daniel H., III; Ao, Tommy

2010-06-01

349

Synchronous ultrasonic Doppler imaging of magnetic microparticles in biological tissues  

International Nuclear Information System (INIS)

We considered applicability of acoustic imaging technology for the detection of magnetic microparticles and nanoparticles inside soft biological tissues. Such particles are widely used for magnetically targeted drug delivery and magnetic hyperthermia. We developed a new method of ultrasonic synchronous tissue Doppler imaging with magnetic modulation for in vitro and in vivo detection and visualization of magnetic ultradisperse objects in soft tissues. Prototype hardware with appropriate software was produced and the method was successfully tested on magnetic microparticles injected into an excised pig liver.

350

Intrahepatic portosystemic venous shunts: diagnosis by Doppler ultrasound  

International Nuclear Information System (INIS)

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

351

Short-time Fourier transform laser Doppler holography  

OpenAIRE

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...

Samson, Benjamin; Atlan, Michael

2012-01-01

352

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

353

Extension of Doppler global velocimetry to periodic flows  

Science.gov (United States)

A three-component, time- and phase-averaging Doppler global velocimetry (DGV) system was developed. Measurements were performed in the cold exhaust flow of a piston engine at two different rotational speeds, with an angular resolution of 5° with respect to the cam-shaft angle. The results gave a very detailed insight into the temporal evolution of the flow field. Phase-averaged DGV measurements were performed in the unsteady periodic flow of a generic swirl nozzle using an acoustic trigger. The measurements help to identify the phenomena of a precessing vortex core. The measurement accuracy of the DGV system was investigated.

Roehle, I.; Willert, C. E.

2001-04-01

354

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.

355

Meteor Trajectory from Multiple Station Head Echo Doppler Observations  

Science.gov (United States)

An improved method for determining a meteor's trajectory from its head echo Doppler signature is presented. This methodology is derived from pioneering work from over half a century ago. The new analytical technique employs head echo data that was simultaneously captured by multiple receiving stations located around a low power beacon. In addition to the geometrical data, Monte Carlo simulations of timing errors were generated and reviewed. The method shows great potential, especially if tighter constraints in the inter-station timing can be achieved.

Steyaert, C.; Verbelen, F.; VVS Beacon Observers

2010-08-01

356

Non-doppler redshift of some galactic objects--  

International Nuclear Information System (INIS)

Redshift observations reported in several galactic objects like binary stars, star clusters, and in the K effect are compared with the predicted non-Doppler redshift caused by the inelastic transmission of photons in gases. It is found that all the observations are compatible with the predicted redshift caused by a gas surrounding the star. The new mechanism explains in a simple way and without the requirement of any of the previous ad hoc hypotheses why so many early-type stars in the solar neighborhood appear to be generally redshifted. This mechanism has important consequences in cosmology

357

Fiber optic laser Doppler anemometry in swirling jets  

Science.gov (United States)

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.

Taghavi, R.; Rice, E. J.

1991-01-01

358

Laser-scanning Doppler photoacoustic microscopy based on temporal correlation  

Science.gov (United States)

We present a methodology to measure absolute flow velocity using laser-scanning photoacoustic microscopy. To obtain the Doppler angle, the angle between ultrasonic detection axis and flow direction, we extracted the distances between the transducer and three adjacent scanning points along the flow and repeatedly applied the law of cosines. To measure flow velocity along the ultrasonic detection axis, we calculated the time shift between two consecutive photoacoustic waves at the same scanning point, then converted the time shift to velocity according to the sound velocity and time interval between two laser illuminations. We verified our method by imaging flow phantoms.

Song, Wei; Liu, Wenzhong; Zhang, Hao F.

2013-05-01

359

Optical spectroscopy and Doppler tomography of Cygnus X-2  

OpenAIRE

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

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

2009-01-01

360

Hardening Doppler Global Velocimetry Systems for Large Wind Tunnel Applications  

Science.gov (United States)

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.

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

2004-01-01

361

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

362

Duplex Color Doppler Sonogram of the Orbital Diseases  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-06-15

363

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

364

Doppler Radar Sounding of Volcanic Eruption Dynamics at Mount Etna  

Science.gov (United States)

Based on the UHF wind profiler technique, a medium power (100 W) pulsed Doppler radar has been specifically developed for the sounding of explosive volcanic jets. Named Voldorad (Volcanological Doppler Radar), this radar can operate at medium distance ( ~0.5 - 4 km) from the active vent and is compact enough to be easily set up on a volcano. The last version of the radar is housed in one unit ( ~60x60x60 cm) and its total weight is ~50 kg. A PC is used for real-time monitoring and data storage. The radar antenna is a 2*2 array of 24 elements Yagi antenna (9° beamwidth) set up on a tripod which is steerable in azimuth and elevation. A pulsed signal (typical duration 0.75 ? s) is transmitted every 100 ? s with a wavelength of 23.5 cm. After amplification and filtering, the received signal is digitized. Each digitized sample corresponds to a received echo at a selected time (i.e. selected range), thus defining the so-called range gates. The Doppler spectrum is then computed for each gate. Three parameters characterizing the ejecta can be deduced from this spectrum: reflectivity, mean velocity and maximum velocity of the jet particles. We present results from experimental campains at Mount Etna during strombolian activity of the SE crater in October 1998 and July 2001. Quasi-continuous and powerful echoes were observed in the central gates, on either side of the jet axis, whereas echoes of side gates were weaker and more intermittent. The temporal variations of the radar signal were analyzed at two time scales. First, the time variations of reflectivity appear to be a good indicator of the long-term evolution of the eruption and also follow the overall trend of the tremor signal. Secondly, detailed analysis of the radar signal (typical integration time ~64 ms) reveals 5 s periodic outbursts during fountain activity. Moreover, the maximum velocity of the jet particles estimated from Doppler spectra might represent the velocity of the finest particles directly entrained by gas.

Dubosclard, G.; Donnadieu, F.; Allard, P.; Cordesses, R.; Hervier, C.; Kornprobst, J.; Lnat, J.; Coltelli, M.; Privitera, E.

2001-12-01

365

Measurement Capabilities of Single-Pulse Planar Doppler Velocimetry  

Science.gov (United States)

Preliminary investigations are described of a method that is capable of measuring instantaneous, 3-D, velocity vectors everywhere in a light sheet generated by a pulsed laser. The technique, here called Planar Doppler Velocimetry (PDV), is a variation of a new concept for velocity measurements that was called Doppler Global Velocimetry (DGV) in its original disclosure. The concept relies on the use of a narrowband laser and measurements of the Doppler shift of scattered light from particles moving with a flow. The Doppler shift is recorded as a variation in transmission through a sharp-edged spectral filter provided by iodine vapor in a cell. Entire fields of velocity can be determined by using a solid-state camera to record the intensity variations throughout the field of view. However, the implementation of DGV has been centered principally on the use of high power, continuous-wave, ion lasers and measurement times that are determined by the 30-ms framing times of standard video cameras. Hence, they provide velocity fields that are averaged in time at least over that period. On the other hand, the PDV concept described in this presentation incorporates a high energy, repetitively pulsed, Nd-YAG laser that is injection-seeded to make it narrowband and then frequency-doubled to provide light at frequencies absorbed by the iodine vapor. The duration of each pulse is less than 10 nanoseconds. When used in combination with nonstandard, scientific quality, solid state cameras, a sequence of images can be obtained that provides instantaneous velocity vectors everywhere in the field of view. The investigations described in this paper include an accurate characterization of the iodine cell spectral behavior and its influence on the PDV measurements, a derivation of the PDV signal analysis requirements, and the unique aspects of the pulsed laser behavior related to this application. In addition, PDV measurements are to be demonstrated using data from a rotating wheel target and from the flow of a subsonic jet. Initially, single optical fiber light collection and photomultiplier detectors will be substituted for solid state cameras. Those results will allow the determination of the fundamental limitations of the PDV technique without the complications of image acquisition and processing. They will then be used to provide an analysis of the measurement capabilities of PDV both in small aerodynamic research wind tunnels and in large wind tunnels designed for production airframe and propulsion testing. Future plans include the implementation of solid state cameras and the development of the required image acquisition and processing software. Eventually, the PDV technique will be applied to an aerodynamic research program related to transonic wing flutter.

McKenzie, Robert L.; Kutler, Paul F. (Technical Monitor)

1994-01-01

366

Transcranial Doppler validation of hemodynamic vertebrobasilar insufficiency diagnosis.  

Science.gov (United States)

Transcranial Doppler (TCD) can be useful in the diagnosis and validation of surgical treatment of vertebrobasilar insufficiency (VBI). A case is reported in which TCD confirmed the diagnosis of vertebrobasilar insufficiency and validated the indication of surgery by detecting a bidirectional flow in a stenotic and compressed vertebral artery. In the postoperative period and at late follow-up TCD demonstrated a restored antegrade flow, as a consequence of a well functioning revascularization. Surgical indication of VBI is rare and TCD can be proposed as part of routine patients' study before a surgical decision is taken. PMID:9177624

Illuminati, G; Caliò, F G; Bertagni, A; Vietri, F; Martinelli, V

1996-01-01

367

Distribution of the extensive Doppler redshift of quasars  

OpenAIRE

We make an analysis of the distribution of the extensive Doppler redshift defined as $\\widetilde{z}_{Dopp}=(z_{abs}-z_{em})/(1+z_{em})$ with a sample of 1317 absorption redshifts available from 401 quasars. The analysis reveals a bi-peak structure in the distribution, with one component located at $\\widetilde{z}_{Dopp}\\simeq 0.00$ and the other at $\\widetilde{z}% _{Dopp}\\simeq -0.01$. A study of some possible causes suggests that the structure can be well interpreted: while ...

Qin, Yi-ping; Liu, Hong-tao; Liang, En-wei; Dong, Yun-ming; Su, Cheng-yue

2004-01-01

368

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

369

Application of coincidence Doppler broadening spectroscopy to simple hydrocarbons  

Science.gov (United States)

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.

Djourelov, N.; Suzuki, T.; Ito, Y.; Shantarovich, V.; Ito, Y.; Kondo, K.; Onoe, J.

2004-03-01

370

Color Doppler Imaging of Cardiac Catheters Using Vibrating Motors  

OpenAIRE

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...

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

2008-01-01

371

Holographic laser Doppler imaging of pulsatile blood flow  

CERN Document Server

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.

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

2015-01-01

372

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

373

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

Science.gov (United States)

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.

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

1975-01-01

374

On the Doppler effect for photons in rotating systems  

CERN Document Server

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,...

Giuliani, Giuseppe

2015-01-01

375

Blood velocity estimation by Doppler ultrasound: Problems and issues  

Science.gov (United States)

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.

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

2002-05-01

376

Velocimetría Doppler de las arterias uterinas en el embarazo  

Directory of Open Access Journals (Sweden)

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.

H\\u00E9ctor Pe\\u00F1a Dehesa

2008-01-01

377

Doppler weather radar as a meteorite recovery tool  

Science.gov (United States)

We report the use of Doppler weather radar as a tool for locating meteorites, both at the time of a fall and from archived radar data. This asset is especially useful for meteorite recovery as it can provide information on the whereabouts of falling meteorites in "dark flight" portion of their descent where information on their flight paths cannot be discerned from more traditional meteorite location techniques such as eyewitness accounts. Weather radar data can provide information from detection in three distinct regimes: (A) direct detection of the rapidly moving, optically bright fireball by distant radars, (B) detection of falling debris to include hand-sample sized rocks, and (C) detection of dust produced by detonation events that can occur tens of minutes and many kilometers laterally removed from the actual fireball locality. We present examples of each, as well as comparisons against man-made debris from a re-entering Soyuz rocket and the Stardust Sample Return Capsule. The use of Doppler weather radar as a supplement to traditional meteorite recovery methods holds the promise of improving both the speed and total number of meteorite recoveries, thereby increasing the number of freshly fallen meteorites for scientific study.

Fries, Marc; Fries, Jeffrey

2010-09-01

378

Method for ambiguity resolution in range-Doppler measurements  

Science.gov (United States)

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.

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

1994-01-01

379

Doppler disc tomography applied to low-mass AGN spin  

Science.gov (United States)

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 active galactic nuclei (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 × 105 M?) 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 note that, as the mass and spin are very low, this appears to favour supermassive black hole (SMBH) growth by chaotic rather than constant accretion.

Middleton, Matthew J.; Ingram, Adam R.

2015-01-01

380

Extremely high-frequency micro-Doppler measurements of humans  

Science.gov (United States)

The development of sensors that are capable of penetrating smoke, dust, fog, clouds, and rain is critical for maintaining situational awareness in degraded visual environments and for providing support to the Warfighter. Atmospheric penetration properties, the ability to form high-resolution imagery with modest apertures, and available source power make the extremely high-frequency (EHF) portion of the spectrum promising for the development of radio frequency (RF) sensors capable of penetrating visual obscurants. Comprehensive phenomenology studies including polarization and backscatter properties of relevant targets are lacking at these frequencies. The Army Research Laboratory (ARL) is developing a fully-polarimetric frequency-modulated continuous-wave (FMCW) instrumentation radar to explore polarization and backscatter properties of in-situ rain, scattering from natural and man-made surfaces, and the radar cross section and micro-Doppler signatures of humans at EHF frequencies, specifically, around the 220 GHz atmospheric window. This work presents an overview of the design and construction of the radar system, hardware performance, data acquisition software, and initial results including an analysis of human micro-Doppler signatures.

Hedden, Abigail S.; Silvious, Jerry L.; Dietlein, Charles R.; Green, Jeremy A.; Wikner, David A.

2014-05-01

381

Depth resolved Doppler broadening spectroscopy in thin metallic films  

International Nuclear Information System (INIS)

Within this contribution the examination of thin metallic films by (C)DB ((coincident) Doppler broadening) measurements at different temperatures is presented. Systems with a gold or copper layer with a thickness between 20 and 500 nm were produced by evaporation deposition on silicon substrates. Doppler broadening and positronium fraction were examined in order to investigate annealing processes. In addition, theses samples as well as gold-copper-silicon systems were studied by depth resolved CDB measurements with the goal to obtain information about temperature dependent diffusion processes at the interface. These measurements were performed by use of the highly intensive positron beam NEPOMUC. Depth resolved DB measurements are used for the determination of the positron diffusion length which is highly sensitive to defect concentration. At high temperatures the thermic desorption of positronium can be detected and additionally considered to determine the diffusion length. Depth resolved CDB measurements allow the detection of the chemical surrounding of defects in layered structures. Recently a new heatable sample holder has been set up in order to achieve a sample temperature up to 1000 K.

382

[Placental 3D Doppler angiography: current and upcoming applications].  

Science.gov (United States)

The placental dysfunction, which seems to be caused by a defect of trophoblastic invasion and impaired uterine vascular remodeling since the first trimester, is responsible in a non-exclusive way for the chronic placental hypoxia, resulting secondarily in the intra-uterine growth restriction (IUGR) and/or pre-eclampsia (PE). The quality of utero-placental vasculature is essential for a proper fetal development and a successful progress of pregnancy. However, the in vivo assessment of placental vascularization with non-invasive methods is complicated by the small size of placental terminal vessel and its complex architecture. Moreover, imaging with contrast agent is not recommended to pregnant women. Until recently, the fetal and maternal vascularization could only be evaluated through pulse Doppler of uterine arteries during pregnancy, which has little clinical value for utero-placental vascularization defects assessment. Recently, a non-invasive study, without use of contrast agent for vasculature evaluation of an organ of interest has become possible by the development of 3D Doppler angiography technique. The objective of this review was to make an inventory of its current and future applications for utero-placental vasculature quantification. The main findings of the literature on the assessment of utero-placental vascularization in physiological situation and major placental vascular dysfunction pathologies such as PE and IUGR were widely discussed. PMID:25307617

Duan, J; Perdriolle-Galet, E; Chabot-Lecoanet, A-C; Callec, R; Beaumont, M; Chavatte-Palmer, P; Tsatsaris, V; Morel, O

2015-02-01

383

An improved Doppler model for obtaining accurate maximum blood velocities.  

Science.gov (United States)

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

Ricci, Stefano; Matera, Riccardo; Tortoli, Piero

2014-09-01

384

Hypercholesterolemia and Myocardial function evaluated via Tissue Doppler Imaging  

Directory of Open Access Journals (Sweden)

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.

Kotaru Pavan

2009-11-01

385

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)

386

Feature extraction from Doppler ultrasound signals for automated diagnostic systems.  

Science.gov (United States)

This paper presented the assessment of feature extraction methods used in automated diagnosis of arterial diseases. Since classification is more accurate when the pattern is simplified through representation by important features, feature extraction and selection play an important role in classifying systems such as neural networks. Different feature extraction methods were used to obtain feature vectors from ophthalmic and internal carotid arterial Doppler signals. In addition to this, the problem of selecting relevant features among the features available for the purpose of classification of Doppler signals was dealt with. Multilayer perceptron neural networks (MLPNNs) with different inputs (feature vectors) were used for diagnosis of ophthalmic and internal carotid arterial diseases. The assessment of feature extraction methods was performed by taking into consideration of performances of the MLPNNs. The performances of the MLPNNs were evaluated by the convergence rates (number of training epochs) and the total classification accuracies. Finally, some conclusions were drawn concerning the efficiency of discrete wavelet transform as a feature extraction method used for the diagnosis of ophthalmic and internal carotid arterial diseases. PMID:16278106

Ubeyli, Elif Derya; Güler, Inan

2005-11-01

387

Optical spectroscopy and Doppler tomography of Cygnus X-2  

CERN Document Server

We present phase resolved optical spectroscopy and Doppler tomography of V1341 Cygni, the optical counterpart to the neutron star low mass X-ray binary Cygnus X-2. We derive a radial velocity curve for the secondary star, finding a projected radial velocity semi-amplitude of K2 = 79 +/- 3 km/s, leading to a mass function of 0.51 +/- 0.06 Msun, ~30% lower than the previous estimate. We tentatively attribute the lower value of K2 (compared to that obtained by other authors) to variations in the X-ray irradiation of the secondary star at different epochs of observations. The limited phase coverage and/or longer timebase of previous observations may also contribute to the difference in K2. Our value for the mass function implies a primary mass of 1.5 +/- 0.3 Msun, somewhat lower than previous dynamical estimates, but consistent with the value found by analysis of type-I X-ray bursts from this system. Our Doppler tomography of the broad He II 4686 line reveals that most of the emission from this line is produced o...

Elebert, P; Torres, M A P; García, M R

2009-01-01

388

Doppler Images and Chromospheric Variability of TWA 6  

CERN Document Server

We present Doppler imaging and Balmer line analysis of the weak-line T Tauri star TWA 6. Using this data we have made one of the first attempts to measure differential rotation in a T Tauri star, and the first detection of a slingshot prominence in such a star. We also show the most direct evidence to date of the existence of solar-type plages in a star other than the Sun. Observations were made over six nights: 11-13th February 2006 and 18-20th February 2006, when spectra were taken with the UCL Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope. Using least-squares deconvolution to improve the effective signal--to--noise ratio we produced two Doppler maps. These show similar features to maps of other rapidly rotating T Tauri stars, i.e. a polar spot with more spots extending out of it down to equator. Comparison of the two maps was carried out to measure the differential rotation. Cross-correlation and parameter fitting indicates that TWA 6 does not have detectable differential rotation. The Balme...

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

2008-01-01

389

Doppler imaging of the helium-variable star a Cen  

CERN Document Server

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

Bohlender, David A; Hechler, P

2010-01-01

390

Doppler effects on velocity spectra observed by MST radars  

Science.gov (United States)

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

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

1986-01-01

391

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)

392

Doppler disc tomography applied to low mass AGN spin  

CERN Document Server

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...

Middleton, Matthew

2014-01-01

393

Intrinsic physical properties and Doppler boosting effects in LSI+61303  

CERN Document Server

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...

Massi, M

2014-01-01

394

Fullwave Simulation of Doppler Reflectometry in Turbulent Plasmas  

Science.gov (United States)

Doppler reflectometry is a microwave diagnostic for plasma density fluctuations and flow velocities. A meaningful interpretation of Doppler reflectometry measurements necessitates the analysis of the wave propagation in the plasma using simulations methods. While the beam path can usually be reconstructed with beam tracing methods, the modeling of the scattering process demands the use of wave simulation codes. Furthermore, in the presence of strong density fluctuations, the response from the plasma is dominated by dispersion and multiple scattering, and hence becomes non-linear. IPF-FD3D [1] is the finite difference time domain code used to investigate the dependence of the scattering efficiency on the various plasma conditions. It uses the full set of Maxwell equations and the electron equation of motion. First results in slab geometry indicate a strong dependence of the scattering efficiency on the density gradient, the turbulent fluctuation strength, and the wave polarisation. In addition, the actual plasma conditions in ASDEX-Upgrade are recreated in the simulation in order to interpret experimental measurements.[4pt] [1] C. Lechte, IEEE Trans. Plasma Sci. 37 (6), 2009

Lechte, Carsten; Stroth, Ulrich; Conway, Garrard

2009-11-01

395

PC-integrated laser Doppler blood flow measurements in skin  

Science.gov (United States)

By irradiation of the skin with a diode laser the blood flow can be measured using the back scattered light. The majority of the back scattered light is scattered from fixed cells, but a small amount is scattered from moving erythrocytes and is Doppler shifted. The mixed light detected with a photodiode leads directly to a photocurrent proportional to the Doppler signal. A laser Doppler blood flow meter was developed, consisting of a PC-AT (66 MHz), a commercial A/D card (14 bit, 100 kHz) and a special head control card for two laser heads. The heads have a diameter of 35 mm and a height of 15 mm. The heads are fixed to the skin with tape. A DOS-Pascal software program provides the measurement, the calculation of a whole blood flow spectrum and shows the results on the screen with a time resolution of up to 50 Hz. The laser head is connected via 2 m cables with the head control card and contains a diode laser (5 mW, 670, 785 nm) a micro lens, two photodiodes and a pre-amplifier. On the head control card there is the current supply for the laser diodes, also the Doppler signals are band passed (400 Hz to 50 kHz), further amplified and fed into the A/D card. On the A/D card the analog signal is sampled with 100 kHz and digitized with 14 bit resolution. With 256 samples a frequency spectrum (128 channels, 0 - 50 kHz) is calculated by a FFT, but only the first 100 channels (0 - 39 kHz) are used to prevent ghosts. The measurements of the Doppler signal of the two laser heads need 5.2 ms and for all software calculations 15 ms are necessary. A quantitative recalculation of a velocity spectrum from the frequency spectrum is only possible if the velocity-, the irradiation-, and scattering-directions are known. In skin the small blood vessels have various directions and because of scattering in skin the irradiation of an erythrocyte can be assumed to be random. With this assumption of a random direction distribution a velocity spectrum can be calculated from the frequency spectrum. A flow spectrum is defined as the product of the velocity and the intensity at this velocity. The flow is defined as the integral over a given region of the flow spectrum. Four independent flow curves can be shown simultaneously on the screen and the frequency region for each flow can be set independently. The flows from low (1 - 3 mm/s) and high (7 - 9 mm/s) velocities show a different behavior and give the possibility to distinguish between the flow in the micro capillaries and larger vessels in the skin.

Doerschel, Klaus; Mueller, Gerhard J.

1996-05-01

396

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)

Full Text Available SciELO Peru | Language: Spanish Abstract in spanish 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

Igor, Huerta; Aída, Borcic.

397

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)

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

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

2013-03-01

398

Reply to Comment on ‘Correct interpretation of two experiments on the transverse Doppler shift’  

Science.gov (United States)

Chen et al (2014 Phys. Scr. 89 067004) wrote a critical comment on the paper ‘Correct interpretation of two experiments on the transverse Doppler shift’ (Zanchini 2012 Phys. Scr. 86 015004). In their comment, the authors agree with the result of the interpretation, which states that the Doppler shift is blue, but criticize the method. Here, a reply to their critical remarks is presented.

Zanchini, Enzo

2014-06-01

399

Efficacy of Doppler Ultrasonography for Assessment of Transjugular Intrahepatic Portosystemic Shunt Patency  

International Nuclear Information System (INIS)

Purpose: To assess the efficacy of Doppler ultrasonography (US) as a noninvasive method for monitoring patency of the transjugular intrahepatic portosystemic shunt (TIPS). Methods: Twenty-nine patients who had received TIPS for bleeding esophagogastric varices and/or refractory ascites with portal hypertension underwent Doppler US studies within 2 weeks after TIPS. Further studies were performed in 15 of them at 6 months, in 9 at 1 year, and in 4 at 2 years for a total of 57 US studies. The US findings were compared with the angiographic findings obtained at the same time. Results: In 45 of the 57 studies, shunt patency was found by Doppler US, correlating to 44 patencies and one occlusion on angiography. Doppler signal in the shunt could not be detected in 12 studies resulting in the diagnosis of shunt occlusion. This correlated with angiographic occlusion in 8 studies and patency in the remaining 4. All angiographically patent shunts that were occluded by Doppler US had various degrees of stenosis. A number of technical factors were found to be responsible for Doppler US false-positive or false-negative diagnoses, some related to the type of stent used. The Doppler US sensitivity was therefore 92%, the specificity 89%. Conclusion: Doppler US is a reliable noninvasive method to evaluate patency of TIPS

400

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

Science.gov (United States)

BACKGROUND: Transmitral Doppler flow indices are used to evaluate diastolic function. Recently, velocities measured by Doppler tissue imaging have been used as an index of left ventricular relaxation. OBJECTIVE: To determine whether Doppler tissue velocities are influenced by alterations in preload. METHODS: Left ventricular preload was altered in 17 patients (all men, mean (SD) age, 49 (8) years) during echocardiographic measurements of left ventricular end diastolic volume, maximum left atrial area, peak early Doppler filling velocity, and left ventricular myocardial velocities during early filling. Preload altering manoeuvres included Trendelenberg (stage 1), reverse Trendelenberg (stage 2), and amyl nitrate (stage 3). Systolic blood pressure was measured at each stage. RESULTS: In comparison with baseline, left ventricular end diastolic volume (p = 0.001), left atrial area (p = 0.003), peak early mitral Doppler filling velocity (p = 0.01), and systolic blood pressures (p = 0.001) were all changed by preload altering manoeuvres. Only left ventricular myocardial velocity during early filling remained unchanged by these manoeuvres. CONCLUSIONS: In contrast to standard transmitral Doppler filling indices, Doppler tissue early diastolic velocities are not significantly affected by physiological manoeuvres that alter preload. Thus Doppler tissue velocities during early left ventricular diastole may provide a better index of diastolic function in cardiac patients by providing a preload independent assessment of left ventricular filling.

Yalcin, F.; Kaftan, A.; Muderrisoglu, H.; Korkmaz, M. E.; Flachskampf, F.; Garcia, M.; Thomas, J. D.

2002-01-01

401

Use of simultaneous Doppler-derived ranges in the geometric mode  

Science.gov (United States)

A mathematical model for the use of ranges derived from integrated Doppler-shifted frequency observations in a satellite trilateration is presented. The model is tested with data taken during the Second European Doppler Observation Campaign (EDOC-2) campaign. The results of this adjustment are compared with the EDOC-2 results.

Schneeberger, R.; Pavlis, D.; Mueller, I. I.

1983-01-01

402

Operator auditory perception and spectral quantification of umbilical artery Doppler ultrasound signals.  

OpenAIRE

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.

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

403

Explanation of the Inverse Doppler Effect Observed in Nonlinear Transmission Lines  

International Nuclear Information System (INIS)

The theory of the inverse Doppler effect recently observed in magnetic nonlinear transmission lines is developed. We explain the crucial role of the backward spatial harmonic in the occurrence of an inverse Doppler effect and draw analogies of the magnetic nonlinear transmission line to the backward wave oscillator

404

Explanation of the inverse Doppler effect observed in nonlinear transmission lines.  

Science.gov (United States)

The theory of the inverse Doppler effect recently observed in magnetic nonlinear transmission lines is developed. We explain the crucial role of the backward spatial harmonic in the occurrence of an inverse Doppler effect and draw analogies of the magnetic nonlinear transmission line to the backward wave oscillator. PMID:16090248

Kozyrev, Alexander B; van der Weide, Daniel W

2005-05-27

405

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

Directory of Open Access Journals (Sweden)

Full Text Available Introduction Cardiovascular diseases are the leading cause of death in the majority of well-developed countries. Importance of early diagnosis Early diagnosis of coronary artery disease is difficult due to blood vessels remodeling, late manifestations of reduced maximal and normal coronary blood flow, and negative correlation between stenosis and plaque burden. Pulsed Doppler tissue imaging Pulsed Doppler tissue imaging is used for assessment of myocardial velocity, whereas classical Doppler imaging is used for measurement of blood flow velocity. Systolic myocardial velocity profile During the systolic phase only a single myocardial motion is registered - S wave. Diastolic myocardial velocity profile There are early and late myocardial relaxation velocities. Impact of coronary artery disease on myocardial velocities Early to late myocardial relaxation velocity ratio is influenced by coronary artery disease. This paper provides practical guidelines for using pulsed doppler tissue imaging. Conclusion Pulsed Doppler tissue imaging is an excellent procedure for early diagnosis of coronary artery disease. .

Zdravkovi? Marija

2007-01-01

406

Laser-diode based 10MHz photoacoustic Doppler flowmetry at 830 nm  

Science.gov (United States)

Photoacoustic Doppler Flowmetry has several potential advantages over its purely acoustical counterpart. The key ones are better inherent contrast and potential molecular information. It is therefore highly desired to continue to develop this modality into a viable complementary tool alongside with Doppler Ultrasound flowmetry. Working towards this goal we have constructed a Photoacoustic Doppler setup based on a combined pair of laser diodes at 830nm and a 10MHz focused acoustical transducer. Using tone-burst intensity modulation, depth-resolved Doppler spectrograms of a phantom vessel containing flowing suspension of carbon particles, were obtained. In order to investigate the conditions required for successful photoacoustic Doppler measurement in blood a k-space photoacoustic simulation was performed. It tested the photoacoustic response which is obtained for moving random spatial distributions of red blood cells and the effect of several parameters, such as particles density, ultrasonic frequency and optical spot size.

Sheinfeld, Adi; Eyal, Avishay

2012-02-01

407

Population statistics of beamed sources. II: Evaluation of Doppler factor estimates  

CERN Document Server

In a companion paper we presented a statistical model for the blazar population, consisting of distributions for the unbeamed radio luminosity function and the Lorentz factor distribution of each of the BL Lac and Flat Spectrum Radio Quasar (FSRQ) classes. Our model has been optimized so that it reproduces the MOJAVE distributions of apparent speeds and redshifts when the appropriate flux limit is applied and a uniform distribution of jet viewing angles is assumed for the population. Here we use this model to predict the Doppler factor distribution for various flux-limited samples for which Doppler factors have been estimated in a variety of ways (equipartition, variability + equipartition, inverse Compton dominance) on a blazar-by-blazar basis. By comparing the simulated and data-estimated Doppler factor distributions in each case, we evaluate the different methods of estimating blazar Doppler factors. We find that the variability Doppler factors assuming equipartition are the ones in the best agreement with...

Liodakis, I

2014-01-01

408

The helicopter flight test analysis of all-fiber laser Doppler velocity sensor  

Science.gov (United States)

This paper gives a novel All-Fiber laser Doppler Velocity Sensor(ALDVS) to measure the relative velocity to the lunar or planetary bodies during the vehicle landing phase. In the beginning of the paper, A brief description of the principle of laser Doppler velocity sensor is given. After that, the paper gives the laser Doppler velocity sensor configuration. The paper introduce the helicopter flight test that was held in Zhengzhou. The altitude of flight is about 3km.The laser Doppler velocity data is analysed. The GPS velocity data and laser Doppler velocity sensor velocity information are compared. Finally, the equivalent distant in moon is calculated and the measurement error is discussed.

Liu, Bo; Sui, Xiao-lin; Zhao, Hong; Xiong, Wen-long; Cao, Chang-dong; Yan, Zi-heng; Zhang, Ying

2013-09-01

409

Caroli's disease: hepatic arterial color doppler signals in the communicating dilated bile ducts  

International Nuclear Information System (INIS)

Three siblings with congenital dilatation of the intrahepatic bile ducts (Caroli's disease) are presented. Bile duct pathology was associated with congenital hepatic fibrosis and polycystic renal disease in all three patients. On color Doppler imaging (CD imaging), multiple small color Doppler signals were observed in or near the vascular radicles within the dilated bile ducts, besides other well-known sonographic findings such as bile duct dilatation, biliary calculi. Doppler frequency spectral analysis confirmed all these color Doppler signals as arterial origin in all patients, showing pulsatile wave pattern. Although portal venous radicles are well known in conventional sonograms or computed tomography(CT), continuous wave patterns were not detected in all patients. In addition to previously reported sonographic findings about Caroli's disease, color Doppler signals showing arterial wave pattern in or around the portal venous radicles within dilated ducts are another helpful diagnostic criteria and those findings are easily depicted on routine sonograms with color mapping

410

Filtering of spacecraft Doppler tracking data and detection of gravitational radiation  

International Nuclear Information System (INIS)

A gravitational-radiation pulse leaves a unique trace on the Doppler tracking record of a spacecraft. In a one-way microwave link the signal appears twice in the Doppler records. In a link that is transponded (or reflected) from the spacecraft the signal is repeated three times. Similarly some of the sources of Doppler system noise also have a unique, repeated signature. These features provide a meaningful way to improve the sensitivity of proposed spacecraft tracking experiments by using an on-board clock of extremely high stability where the spacecraft and Earth stations each obtain Doppler data. We construct software filters for data from this type of experiment, and using numerical simulations we compare the sensitivity of the proposed new experiments to current ones, where two-way Doppler data are obtained

411

Collapse and revival of the Doppler-Rabi oscillations of a moving atom in a cavity  

International Nuclear Information System (INIS)

Collapse and revival of the Doppler-Rabi oscillations of a two-level atom moving in a cavity electromagnetic field are analyzed. The coupled atom-field dynamics are predicted accurately by numerical calculation and approximately by using the stationary phase approximation combined with the Poisson summation formula. The collapse and revival patterns are shown to be qualitatively different in the cases of moving atom and atom at rest. In particular, quantum revivals of Doppler-Rabi oscillations occur with a period determined by the Doppler shift of the atomic transition frequency. This regime of Doppler-Rabi oscillations requires that the Rabi frequency and the Doppler shift satisfy the condition ?R D. Under the inverse relation, the collapse- revival phenomenon generally does not occur. It is shown that even a small amount of atom-cavity detuning eliminates collapse-revival behavior. The analysis is performed for both coherent and thermal cavity fields

412

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

413

Transthoracic Doppler echocardiography to predict optimal tube pulsing window for coronary artery CT angiography  

International Nuclear Information System (INIS)

Rationale and objective: To evaluate the feasibility of transthoracic Doppler echocardiography to determine the optimal pulsing windows for CT coronary angiography to narrow the pulsing windows further, especially in higher heart rate. Materials and methods: Doppler was performed on 135 patients before CT scanning. For Doppler, the intervals with minimal motion were evaluated during both systole and diastole integrating electrocardiogram (ECG) intervals. For CT scanning, the retrospective ECG-gating was applied and the optimal reconstruction intervals were determined. The accuracy of Doppler analysis to predict the optimal reconstruction intervals was tested. The predicted length of pulsing windows was compared between Doppler analysis and traditional prospective ECG-gating protocol (heart rate ? 65 bpm, 60–76%; 66–79 bpm, 30–77%; ?80 bpm, 31–47%). Results: According to Doppler analysis, the mean length of intervals with minimal motion in systole was 106.4 ± 39.2 ms and 125.2 ± 92.0 ms in diastole. When the intervals with minimal motion during diastole > 90 ms, the optimal reconstruction intervals were located at diastole; otherwise, at systole (P < 0.001). The optimal reconstruction intervals in 93.8% (132/135) patients could be predicted accurately by Doppler analysis. If the optimal reconstruction intervals predicted by Doppler were applied as the exposure windows, the mean length of pulsing windows should has been 105.2 ± 69.4 ms (range: 26.9–510.3 ms), which was significantly shorter than that of traditional prospective ECG-gating protocol (232.0 ± 120.2 ms, range: 93.2–427.3 ms, P < 0.001). Conclusion: Doppler can help detecting the optimal pulsing windows accurately. Prospective ECG-gating incorporating Doppler analysis may narrow pulsing windows significantly while maintaining image quality

414

Magnetic Compensation for Second-Order Doppler Shift in LITS  

Science.gov (United States)

The uncertainty in the frequency of a linear-ion-trap frequency standard (LITS) can be reduced substantially by use of a very small magnetic inhomogeneity tailored to compensate for the residual second-order Doppler shift. An effect associated with the relativistic time dilatation, one cause of the second-order Doppler shift, is ion motion that is attributable to the trapping radio-frequency (RF)electromagnetic field used to trap ions. The second-order Doppler shift is reduced by using a multi-pole trap; however it is still the largest source of systematic frequency shift in the latest generation of LITSs, which are among the most stable clocks in the world. The present compensation scheme reduces the frequency instability of the affected LITS to about a tenth of its previous value. The basic principles of prior generation LITSs were discussed in several prior NASA Tech Briefs articles. Below are recapitulated only those items of basic information necessary to place the present development in context. A LITS includes a microwave local oscillator, the frequency of which is stabilized by comparison with the frequency of the ground state hyperfine transition of 199Hg+ ions. The comparison involves a combination of optical and microwave excitation and interrogation of the ions in a linear ion trap in the presence of a nominally uniform magnetic field. In the current version of the LITS, there are two connected traps (see figure): (1) a quadrupole trap wherein the optical excitation and measurement take place and (2) a 12-pole trap (denoted the resonance trap), wherein the microwave interrogation takes place. The ions are initially loaded into the quadrupole trap and are thereafter shuttled between the two traps. Shuttling ions into the resonance trap allows sensitive microwave interrogation to take place well away from loading interference. The axial magnetic field for the resonance trap is generated by an electric current in a finely wound wire coil surrounded by magnetic shields. In the quadrupole and 12-pole traps, the potentials are produced by RF voltages applied to even numbers (4 and 12, respectively) of parallel rods equally spaced around a circle. The polarity of the voltage on each rod is opposite that of the voltage on the adjacent rod. As a result, the amplitude of the RF trapping field is zero along the centerline and increases, with radius, to a maximum value near the rods.

Burt, Eric; Tjoelker, Robert

2008-01-01

415

Avaliação com Doppler colorido e espectral da veia porta de cães / Evaluation of portal vein in dogs by color and spectral Doppler imaging  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A perfusão total do fígado e suas contribuições relativas, pelo sistema portal e pela artéria hepática, podem estar alteradas por vários processos hepáticos, como doença hepato-celular difusa, neoplasia e shunts intra-hepáticos. O estudo do comportamento do fluxo sangüíneo nos vasos do fígado por me [...] io da ultra-sonografia Doppler tem demonstrado que este é um método viável não-invasivo e de grande auxílio, principalmente na avaliação da hemodinâmica portal. São duas as modalidades de ultra-sonografia Doppler com maior aplicação na rotina para avaliação de fluxo nos vasos abdominais, o Doppler espectral e o Doppler colorido. Na doença hepática crônica, ocorre alteração da complacência hepática devido à fibrose ou à cirrose, as quais acarretam alterações vasculares, levando ao aumento da pressão venosa portal. As principais indicações desse exame são os casos em que há suspeita de hipertensão portal. A hemodinâmica portal é avaliada pela mensuração de sua área, da velocidade média, do volume de fluxo no vaso e do índice de congestão portal. Esta revisão de literatura tem como objetivo descrever os princípios físicos básicos da ultra-sonografia Doppler e sua aplicação na avaliação da hemodinâmica portal nos cães. Abstract in english Total hepatic perfusion by portal system and hepatic arteria as well as its respective average contributions, can be affected for several hepatic processes, such as diffuse liver disease, neoplasm and intrahepatic shunts. Blood flow exams of the liver vessels using Doppler ultrasonography, appeared [...] as a viable, non-invasive and helpful diagnostic method for the hemoportal dynamic evaluation. There are two Doppler ultrasonographic modalities most frequently used in routine for evaluation of the abdominal vessels flow, spectral Doppler imaging and color-flow Doppler imaging. In chronic liver disease, alteration of hepatic complacency occurs because of either fibrosis or cirrhosis, bringing to vascular alterations which provoke an increase in portal pressure. The main indications for this exam are cases suspicious of portal hypertension. Portal hemodynamics is evaluated by measurements of the area, average speed, flow volume and portal vein congestion index. The objectives of this review are to describe the basic physical principles of Doppler ultrasonography and its use for evaluation of portal hemodynamics in dogs.

Raquel, Sartor; Maria Jaqueline, Mamprim.

2009-04-01

416

An extra-heating mechanism in Doppler-cooling experiments  

CERN Document Server

In this paper we experimentally and theoretically investigate laser cooling of Strontium 88 atoms in one dimensional optical molasses. In our case, since the optical cooling dipole transition involves a $J_g=0$ groundstate, no Sisyphus-type mechanisms can occur. We are thus able to test quantitatively the predictions of the Doppler-cooling theory. We have found, in agreement with other similar experiments, that the measured temperatures are systematically larger than the theoretical predictions. We quantitatively interpret this discrepancy by taking into consideration the extra-heating mechanism induced by transverse spatial intensity fluctuations of the optical molasses. Experimental data are in good agreement with Monte-Carlo simulations of our theoretical model. We thus confirm the important role played by intensity fluctuations in the dynamics of cooling and for the steady-state regime.

Chaneliere, T; Kaiser, R; Miniatura, C; Wilkowski, D; Chaneliere, Thierry; Meunier, Jean-Louis; Kaiser, Robin; Miniatura, Christian; Wilkowski, David

2004-01-01

417

The mobile SOUSY Doppler radar: Technical design and first results  

Science.gov (United States)

On the basis of the experience obtained with the stationary SOUSY radar in the Harz mountains, a mobile VHF Doppler system was developed during the last two years. The electronic part is installed in a 20-foot container and was tested for the first time during a joint experiment at the Arecibo Observatory (Puerto Rico) using a special log-periodic aerial to illuminate the 300-m dish. In 1982 this system was extended by designing a mobile phased antenna array with 576 Yagi elements. The grouping of the single Yagis, the feeding network, the phase shifters, the power splitters, and the transmit receive switch are described. A summary of results obtained during the first two campaigns is presented as well as a survey of future programs demonstrating the flexibility of this mobile system.

Czechowsky, P.; Schmidt, G.; Rüster, R.

1984-01-01

418

Color-flow Doppler imaging in suspected extremity venous thrombosis  

International Nuclear Information System (INIS)

Color-flow Doppler imaging (CFDI) (Quanatum, 5 and 7.5 MHz, linear array) has been performed on 23 extremities (nine positive for venous thrombosis, 14 negative) with venographic correlation. CFDI criteria evaluated were venous color-flow respiratory variation, augmentation, compressibility, valve competence, and intraluminal echogenic filling defects. Both CFDI and venography were evaluated independently and prospectively. CFDI and venography agreed in all six cases of femoral vein thrombosis and eight of nine cases of popliteal vein thrombosis. CFDI was negative in one instance of recanalized popliteal vein thrombosis. Recanalized femoral vein thrombosis was documented in three patients by CFDI when the vein was nonopacified on conventional venography. CFDI provides a rapid and accurate assessment of the femoral popliteal venous system and can distinguish an occluded from a recanalized thrombus. Initial experience with auxiliary subclavian venous thrombus has produced equally accurate results

419

Doppler broadening thermometry based on cavity ring-down spectroscopy  

CERN Document Server

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) in the determined linewidth values by several hours' measurement at a sample pressure of 1.5 Pa. The influence on the spectroscopy-determined temperatures has been investigated, including the "hidden" weak lines overlapped with the selected transition for DBT measurements. The reproducibility has also been examined to be better than 10 ppm, and it indicates that the instrument is feasible for DBT measurement toward a precision at the ppm level.

Cheng, C -F; Sun, Y R; Tan, Y; Kang, P; Hu, S -M

2015-01-01

420

A novel, multichannel, comb-frequency Doppler backscatter system  

International Nuclear Information System (INIS)

Doppler backscattering has emerged in recent years as a powerful diagnostic tool in high temperature fusion plasmas. The technique is sensitive to plasma turbulence flow and has been utilized to determine radial electric field and to study geodesic acoustic modes, zonal flows, and intermediate scale density turbulence. The current manuscript describes a novel technique for creating a stable, multichannel system covering the V-band frequency range (50-75 GHz) which enables simultaneous monitoring of turbulent flows and fluctuation levels at eight distinct spatial locations. The system is based on a high-frequency, low phase noise comb-frequency generator combined with a filter bank and quadrature detection system. The system is now in operation on DIII-D and has allowed monitoring of the flow and turbulence levels across the plasma radius during events such as the L-H transition.

421

Flight test performance of a high precision navigation Doppler lidar  

Science.gov (United States)

A navigation Doppler Lidar (DL) was developed at NASA Langley Research Center (LaRC) for high precision velocity measurements from a lunar or planetary landing vehicle in support of the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project. A unique feature of this DL is that it has the capability to provide a precision velocity vector which can be easily separated into horizontal and vertical velocity components and high accuracy line of sight (LOS) range measurements. This dual mode of operation can provide useful information, such as vehicle orientation relative to the direction of travel, and vehicle attitude relative to the sensor footprint on the ground. System performance was evaluated in a series of helicopter flight tests over the California desert. This paper provides a description of the DL system and presents results obtained from these flight tests.

Pierrottet, Diego; Amzajerdian, Farzin; Petway, Larry; Barnes, Bruce; Lockard, George

2009-05-01

422

Positron annihilation Doppler broadening study of Xe-implanted aluminum  

International Nuclear Information System (INIS)

Positron annihilation Doppler broadening measurements were conducted to characterize information of defects in 380 keV Xe+-implanted aluminum upon thermal annealing at temperatures ranging from 100 to 600 °C. The results suggest a broad distribution in the depth of vacancy-type defects in all the as-implanted samples. Meanwhile, with an increase in implantation dose the defect-rich region shifts toward the sample surface. It was found that increasing the annealing temperature triggers surface-directed migration and coalescence of vacancy and XenVm clusters in samples with implantation doses of 1E15 and 1E16 Xe+cm?2. In the sample implanted with a high dose of 1E17 Xe+cm?2, positron annihilation revealed a decomposition and even elimination of such defects under post-implantation annealing treatment.

423

Droplet sizing calibration of the Phase Doppler Particle Analyzer  

Energy Technology Data Exchange (ETDEWEB)

The Phase Doppler Particle Analyzer (PDPA) is an LDV-based instrument for simultaneous measurement of single particle size and velocity. A PDPA calibration was performed using well-characterized liquid droplets in the 4 to 80 ..mu..m diameter range. Two test liquids were used: oleic acid and kerosene. A standard PDPA instrument and a fiber-optic probe PDPA system were tested. The standard instrument measurements agreed with expected droplet diameters to within the droplet generation accuracy for droplets above 15 ..mu..m diameter, and had a measurement accuracy of about 2 ..mu..m for smaller droplets. The fiber-optic probe system exhibited similar behavior, although the 2 ..mu..m sizing uncertainty extended to droplets as large as 25 ..mu..m. The measurement uncertainties in the small diameter ranges are in qualitative agreement with the light-scattering computations of Al-Chalabi et al. (1988) and Saffman et al. (1984). 7 refs., 4 figs.

O' Hern, T.J.; Rader, D.J.; Ceman, D.L.

1989-01-01

424

Doppler images of the eclipsing binary ER Vulpeculae  

Science.gov (United States)

We present Doppler images of both components of the eclipsing binary system ER Vul, based on the spectra obtained in 2004 November, 2006 September and 2008 November. The least-squares deconvolution technique is used for enhancing the signal-to-noise ratios of the observed profiles. The new surface images reveal that both stars of ER Vul show strong starspot activities and the starspots appear at various latitudes. The surface maps of 2006 and 2008 both show the presence of large high-latitude starspots on each component of ER Vul. We find no obvious phase shift of the active regions during our observations. The longitude distributions of starspots are non-uniform on both stars. At low-to-mid latitudes, the active regions are almost exclusively found in the hemisphere facing the other star. However, we find no pronounced concentration of spots at the sub-stellar points.

Xiang, Yue; Gu, Shenghong; Cameron, A. Collier; Barnes, J. R.

2015-02-01

425

How reliable is Zeeman Doppler Imaging without simultaneous temperature reconstruction?  

CERN Document Server

Aims: The goal of this study is to perform numerical tests of Zeeman Doppler Imaging (ZDI) to asses whether correct reconstruction of magnetic fields is at all possible without taking temperature into account for stars in which magnetic and temperature inhomogeneities are spatially correlated. Methods: We used a modern ZDI code employing a physically realistic treatment of the polarized radiative transfer in all four Stokes parameters. We generated artificial observations of isolated magnetic spots and of magnetic features coinciding with cool temperature spots and then reconstructed magnetic and temperature distributions from these data. Results: Using Stokes I and V for simultaneous magnetic and temperature mapping for the star with a homogeneous temperature distribution yields magnetic field strengths underestimated by typically 10-15% relative to their true values. When temperature is kept constant and Stokes I is not used for magnetic mapping, the underestimation is 30-60%. At the same time, the strength...

Rosén, Lisa

2012-01-01

426

Spacecraft-Doppler gravity-wave detection. II. Results  

International Nuclear Information System (INIS)

Results are presented from an experiment to detect very-low-frequency-band gravitational waves by Doppler tracking the Voyager I spacecraft at its solar oppositions in January, 1979 and March, 1980. Searches were performed for both coherent pulses and an incoherent background. No gravity-wave pulses were seen with amplitudes greater than 3 x 10-14 at 500-sec sample times, and no gravity-wave background was detected with an amplitude power spectral density given by S/sub h/=10-27f-1 (Hz-1), where f is the Fourier frequency. The limits to sensitivity come from plasma scintillation at low Fourier frequencies and thermal system noise at high frequencies, though there appears to be tentative evidence also for a detectable level of some other low-frequency noise source, probably troposphere scintillation. Methods of getting around these limits in the future are also discussed

427

High resolution ion Doppler spectroscopy at Prairie View Rotamak  

International Nuclear Information System (INIS)

A fast ion Doppler spectroscopy (IDS) diagnostic system is installed on the Prairie View Rotamak to measure ion temperature and plasma flow. The diagnostic employs a single channel photomultiplier tube and a Jarrell-Ash 50 monochromator with a diffraction grating line density of 1180 lines/mm, which allows for first order spectra of 200–600 nm. The motorized gear of the monochromator allows spectral resolution of 0.01 nm. Equal IDS measurements are observed for various impurity emission lines of which carbon lines exhibit stronger intensities. Furthermore, the diagnostics is examined in an experiment where plasma experiences sudden disruption and quick recovery. In this case, the IDS measurements show ?130% increase in ion temperature. Flow measurements are shown to be consistent with plasma rotation.

428

Characterizing Ocean Turbulence from Argo, Acoustic Doppler, and Simulation Data  

Science.gov (United States)

Turbulence is inherently chaotic and unsteady, so observing it and modeling it are no easy tasks. The ocean's sheer size makes it even more difficult to observe, and its unpredictable and ever-changing forcings introduce additional complexities. Turbulence in the oceans ranges from basin scale to the scale of the molecular viscosity. The method of energy transfer between scales is, however, an area of active research, so observations of the ocean at all scales are crucial to understanding the basic dynamics of its motions. In this collection of work, I use a variety of datasets to characterize a wide range of scales of turbulence, including observations from multiple instruments and from models with different governing equations. I analyzed the largest scales of the turbulent range using the global salinity data of the Argo profiling float network. Taking advantage of the scattered and discontinuous nature of this dataset, the second-order structure function was calculated down to 2000m depth, and shown to be useful for predicting spectral slopes. Results showed structure function slopes of 2/3 at small scales, and 0 at large scales, which corresponds with spectral slopes of -5/3 at small scales, and -1 at large scales. Using acoustic Doppler velocity measurements, I characterized the meter- to kilometer-scale turbulence at a potential tidal energy site in the Puget Sound, WA. Acoustic Doppler current profiler (ADCP) and acoustic Doppler velocimeter (ADV) observations provided the data for an analysis that includes coherence, anisotropy, and intermittency. In order to more simply describe these features, a parameterization was done with four turbulence metrics, and the anisotropy magnitude, introduced here, was shown to most closely capture the coherent events. Then, using both the NREL TurbSim stochastic turbulence generator and the NCAR large-eddy simulation (LES) model, I calculated turbulence statistics to validate the accuracy of these methods in reproducing the tidal channel. TurbSim models statistics at the height of a turbine hub (5m) well, but do not model coherent events, while the LES does create these events, but not realistically in this configuration, based on comparisons with observations. Each of the datasets have disadvantages when it comes to observing turbulence. The Argo network is sparse in space, and few measurements are taken simultaneously in time. Therefore spatial and temporal averaging is needed, which requires the turbulence to be homogeneous and stationary if it is to be generalized. Though the acoustic Doppler current profiler provides a vertical profile of velocities, the fluctuations are dominated by instrument noise and beam spread, preventing it from being used for most turbulence metrics. ADV measurements have much less noise, and no beam spread, but the observations are made at one point in space, limiting us to temporal statistics or an assumption of "frozen turbulence" to infer spatial scales. As for the models, TurbSim does not have any real-world forcing, and uses parameterized spectra, and coherence functions and randomizes phase information, while LES models must make assumptions about sub-grid scales, which may be inaccurate. Additionally, all models are set up with idealizations of the forcing and domain, which may make the results unlike observations in a particular location and time. Despite these difficulties in observing and characterizing turbulence, I present several quantities that use the imperfect, yet still valuable observations, to attain a better description of the turbulence in the oceans.

McCaffrey, Katherine

429

Laser doppler techniques for sizing particulate pollutants and therapeutic aerosols  

Science.gov (United States)

A particle size analyzer based on laser Doppler velocimetry has been developed for measuring, in real time, the aerodynamic size distribution of aerosol particulates in the respirable range 0.1 to 10.0 ?m in diameter. The instrument, a single particle aerodynamic relaxation time analyzer, measures the aerodynamic relaxation time of individual suspended particles and droplets without removing the particulates from their aerosol phase. Measurements can be made at a maximum count rate of 200 particles/sec, although coincidence error restricts the count rate to a lower limit. The size resolution is within ±5% of the measured aerodynamic diameter. Currently, three prototype SPART analyzers are being used for: (1) studying aerodynamic size distribution and lung retention of therapeutic aerosols, (2) measuring fractional efficiency of electrostatic precipitators as a function of size and electrical resistivity of flyash particles, and (3) characterizing atmospheric and household aerosols.

Mazumder, M. K.; Hiller, F. C.; Ware, R. E.; Wilson, J. D.; McLeod, P. C.

1980-12-01

430

Externally Dispersed Interferometry for Resolution Boosting and Doppler Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

Externally dispersed interferometry (EDI) is a rapidly advancing technique for wide bandwidth spectroscopy and radial velocimetry. By placing a small angle-independent interferometer near the slit of an existing spectrograph system, periodic fiducials are embedded on the recorded spectrum. The multiplication of the stellar spectrum times the sinusoidal fiducial net creates a moire pattern, which manifests high detailed spectral information heterodyned down to low spatial frequencies. The latter can more accurately survive the blurring, distortions and CCD Nyquist limitations of the spectrograph. Hence lower resolution spectrographs can be used to perform high resolution spectroscopy and radial velocimetry (under a Doppler shift the entire moir{acute e} pattern shifts in phase). A demonstration of {approx}2x resolution boosting (100,000 from 50,000) on the Lick Obs. echelle spectrograph is shown. Preliminary data indicating {approx}8x resolution boost (170,000 from 20,000) using multiple delays has been taken on a linear grating spectrograph.

Erskine, D J

2003-12-01

431

Application of laser Doppler velocimeter to chemical vapor laser system  

Science.gov (United States)

A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

1993-01-01

432

Short-time Fourier transform laser Doppler holography  

CERN Document Server

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 Fourier transformation. The measurement band can be positioned freely within the low radio-frequency spectrum by tuning the frequency of the reference beam in real-time. Video-rate image rendering is achieved by streamline image processing with commodity computer graphics hardware. This experimental scheme is validated by a non-contact vibrometry experiment.

Atlan, Michael

2012-01-01

433

Doppler effect measurement in FCA assembly XII-1  

International Nuclear Information System (INIS)

Doppler reactivity worths of 238U and structural materials (iron and nickel) were measured at the internal blanket and the core region in FCA assembly XII-1 which is the mock-up of a large axially heterogeneous core. The measurements were also performed in sodium-voided core. The experiments were carried out using the heated sample oscillation technique with an accuracy of 1 x 10-7 ?k/k. The range of temperature change was from the room temperature up to 800 0C. The analysis was made using the 70 group JFS-3-J2 data set and compared with the measured results. In the internal blanket and the core region the calculation agrees well with the measured values, on the other hand, in the sodium-voided core the calculation for 238U underestimates the measurement by 10 %. (author)

434

Fluorescence during Doppler cooling of a single trapped atom  

International Nuclear Information System (INIS)

We investigate the temporal dynamics of Doppler cooling of an initially hot single trapped atom in the weak-binding regime using a semiclassical approach. We develop an analytical model for the simplest case of a single vibrational mode for a harmonic trap, and show how this model allows us to estimate the initial energy of the trapped particle by observing the time-dependent fluorescence during the cooling process. The experimental implementation of this temperature measurement provides a way to measure atom heating rates by observing the temperature rise in the absence of cooling. This method is technically relatively simple compared to conventional sideband detection methods, and the two methods are in reasonable agreement. We also discuss the effects of rf micromotion, relevant for a trapped atomic ion, and the effect of coupling between the vibrational modes on the cooling dynamics

435

Fluorescence during Doppler cooling of a single trapped atom  

CERN Document Server

We investigate the temporal dynamics of Doppler cooling of an initially hot single trapped atom in the weak binding regime using a semiclassical approach. We develop an analytical model for the simplest case of a single vibrational mode for a harmonic trap, and show how this model allows us to estimate the initial energy of the trapped particle by observing the fluorescence rate during the cooling process. The experimental implementation of this temperature measurement provides a way to measure atom heating rates by observing the temperature rise in the absence of cooling. This method is technically relatively simple compared to conventional sideband detection methods, and the two methods are in reasonable agreement. We also discuss the effects of RF micromotion, relevant for a trapped atomic ion, and the effect of coupling between the vibrational modes on the cooling dynamics.

Wesenberg, J H; Leibfried, D; Blakestad, R B; Britton, J; Home, J P; Itano, W M; Jost, J D; Knill, E; Langer, C; Ozeri, R; Seidelin, S; Wineland, D J

2007-01-01