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1

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

International Nuclear Information System (INIS)

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

2

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)

3

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

International Nuclear Information System (INIS)

25, 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)

4

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

5

Right Ventricular Tissue Doppler in Space Flight  

Science.gov (United States)

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

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

2010-01-01

6

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

Directory of Open Access Journals (Sweden)

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

C. Lightowler

2006-12-01

7

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

Scientific Electronic Library Online (English)

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

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

2006-12-01

8

Welcome to the TEI’10 Proceedings  

DEFF Research Database (Denmark)

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

Pederson, Thomas; Shaer, Orit

2010-01-01

9

Effect of dobutamine on a Doppler echocardiographic index of combined systolic and diastolic performance.  

Science.gov (United States)

Dobutamine stress echocardiography has become accepted in the evaluation of cardiac functional reserve. Although the Doppler-derived index of combined systolic/diastolic myocardial performance (Tei index) has been reported to be easily obtainable and useful for predicting left ventricular performance, the effect of dobutamine on the Tei index has not been determined in children. To assess the effect of dobutamine on the Tei index, 8 patients who had undergone surgery for ventricular septal defect and 7 patients who had a history of Kawasaki disease were examined. Echocardiographic recordings were obtained before and after dobutamine infusion (5 microg/kg per minute). Variables measured were transmitral flow velocities (E, A, E/A), rate-corrected mean velocity of circumferential fiber shortening (rate-corrected Vcf), and IMP. We measured isovolumic contraction time (ICT), isovolumic relaxation time (IRT), and ejection time (ET) and then calculated the Tei index using the following formula: Tei index = (ICT + IRT)/ET. Dobutamine infusion increased rate-corrected Vcf (29%, p ICT, and IRT were found to decrease during dobutamine infusion. The magnitude of the change in the ICT (-21%, p ICT/ET (-21%, p < 0.01) and a slight decrease in IRT/ET (-12%, p < 0.05). The Tei index has potential as a sensitive indicator of the effects of inotropic stimilation on global left ventricular function. PMID:12530494

Harada, K; Tamura, M; Toyono, M; Yasuoka, K

2002-01-01

10

[Prognostic value of the myocardial performance (Tei) index in patients with chronic heart failure].  

Science.gov (United States)

Aim of this study was to define the prognostic value of Tei index compared with other clinical and instrumental parameters in elderly patients with chronic heart failure (CHF) observed in outpatient conditions. A total of 97 patients aged 60 to 85 years with symptoms of CHF NYHA class II--IV due to coronary heart disease or hypertension were included. Clinical examination, a 6-minute walk test, echocardiography with determination of Tei index were carried out. There was statistically significant difference between survival among patients with Tei index > or = 0.6 and patients with Tei index or = 0.6 (p or = 0.6. Among patients with preserved LVEF (LVEF > 45%) prognostic value of Tei index was similar to that of LV EF. PMID:24654433

Larina, V N; Bart, B Iu; Dergunova, E N; Alekhin, M N

2013-01-01

11

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

12

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Heiden, Serge

2010-01-01

13

Manuel d'encodage XML-TEI - édition numérique de manuscrits baroques  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ce manuel présente les recommandations d'encodage en XML-TEI en vue de l'édition de textes du XVIIe siècle. Il a été établi dans le cadre d'un projet européen par les deux autrices, encodeuses elles-mêmes. Elles ont suivi cette méthodologie rigoureuse et élaboré les recommandations qu'elles expliquent ici. Ce manuel répond aux exigences d'un projet de recherche européen mais également à un souci pédagogique pour les équipes de recherche actuelles qui désirent éditer numéri...

Dufournaud, Nicole; Gratsac Legendre, Vale?rie

2012-01-01

14

Doppler Tomography  

CERN Document Server

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 coping with it. Then I move on to look at the results of Doppler Tomography applied to cataclysmic variable stars. Outstanding successes to date are the discovery of two-arm spiral shocks in cataclysmic variable accretion discs and the probing of the stream/magnetospheric interaction in magnetic cataclysmic variable stars. Doppler tomography has also told us much about the stream/disc interaction in non-magnetic systems and the irradiation of the secondary star in all systems. The latter indirectly reveals such effects as shadowing by the a...

Marsh, T R

2000-01-01

15

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

Scientific Electronic Library Online (English)

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

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

16

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

Directory of Open Access Journals (Sweden)

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

Cláudio Roberto Vieira Braga

2009-11-01

17

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

Directory of Open Access Journals (Sweden)

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

Boban Marko

2013-12-01

18

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

19

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

Science.gov (United States)

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

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

2009-05-01

20

Doppler flowmeter  

Science.gov (United States)

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

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

1983-01-01

 
 
 
 
21

Image-derived input functions for PET brain studies  

International Nuclear Information System (INIS)

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

22

Laser Doppler Velocimetry Workshop  

Science.gov (United States)

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

Owen, R. B.

1979-01-01

23

Laser Doppler Velocimetry Workshop.  

Science.gov (United States)

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

R. B. Owen

1979-01-01

24

The doppler ultrasound  

International Nuclear Information System (INIS)

The discovery and development of Doppler ultrasound has had a great influence on Medical practice since it allows the noninvasive study of vascular pathology, both arterial and venous, as well as the flow patterns of the different parenchyma. This article deals with the principles, limitations and interpretation of the Doppler signal, as well as the different Doppler ultrasound systems routinely employed in Medicine

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

Myocardial performance in asphyxiated full-term infants assessed by Doppler tissue imaging.  

Science.gov (United States)

The aim of this study was to assess myocardial performance of full-term infants with perinatal asphyxia using Doppler tissue imaging (DTI) and to correlate it with serum cardiac troponin T (cTnT) concentrations. Twenty-five asphyxiated and 20 nonasphyxiated term infants were investigated. Serum cTnT concentrations were measured between 12 and 24 h of life. Conventional two-dimensional Doppler echocardiography and DTI were done during the first 72 h of life. Right ventricular (RV) and left ventricular (LV) Tei indexes were significantly higher in asphyxiated neonates (mean +/- SD: 0.45 +/- 0.05 vs. 0.28 +/- 0.05, P < 0.001 and 0.51 +/- 0.04 vs. 0.38 +/- 0.04, P < 0.001, respectively). Mitral and tricuspid systolic (Sm) velocities were significantly lower in asphyxiated neonates (mean +/- SD: 5.06 +/- 0.89 vs. 6.89 +/- 0.94 cm/s, P < 0.001 and 5.78 +/- 0.58 vs. 6.69 +/- 0.87 cm/s, P < 0.001, respectively). cTnT concentrations were significantly higher in asphyxiated neonates [median (range): 0.17 (0.05-0.23) vs. 0.03 (0-0.07) microg/l, P < 0.001)], and they correlated positively with the LV Tei index (r = 0.67, P < 0.001) and the RV Tei index (r = 0.68, P < 0.001) and negatively with the mitral systolic (Sm) velocity (r = -0.68, P < 0.001) and tricuspid systolic (Sm) velocity (r = -0.41, P = 0.01). A higher cTnT was a significant predictor of mortality, whereas fractional shortening (FS) and DTI measurements did not show any significant predictive value. The DTI technique appears to be more sensitive than conventional echocardiography in the early detection of myocardial dysfunction induced by perinatal asphyxia in full-term infants. PMID:20143054

Matter, Mohamed; Abdel-Hady, Hesham; Attia, Gehan; Hafez, Mona; Seliem, Wael; Al-Arman, Mohamed

2010-07-01

27

Christian Doppler and the Doppler effect  

Science.gov (United States)

A summary is given of Doppler's life and career. He was born 180 years ago on November 29, 1803, in Salzburg, Austria. He died on March 17, 1853 in Venice. The effect bearing his name was first announced in a presentation before the Royal Bohemian Society of the Sciences in Prague on May 25, 1842. Doppler considered his work a generalization of the aberration theorem as discovered by Bradley. With it came the inference that the perception of physical phenomena can change with the state of motion of the observer. Acceptance of the principle was not without controversy. In 1852, the mathematician Petzval claimed that no useful scientific deductions can be made from Doppler's elementary equations. In 1860, Ernst Mach resolved the misunderstanding that clouded this controversy. The Doppler effect is alive and well. Its role in radio science and related disciplines is enumerated.

Toman, Kurt

1984-04-01

28

Determination of the Accuracy of Echocardiographic Parameters Mitral Inflow S/D Ratio and Tei Index to Detect Left Ventricular Dysfunction in Pediatric Patients with Mitral Regurgitation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background and Objectives: Congenital heart diseases are one of the most common anomalies in infancy. This study was performed aimed to determine the accuracy, sensitivity and specificity of the left ventricular Tei index (TX) and the systolic to diastolic duration ratio (S/D) to detect ventricular dysfunction in pediatric pediatrics with congenital heart defect accompanied by mitral regurgitation.Methods: In this study, systolic and diastolic function of left ventricle was evaluated by TX an...

Mohammad Hossein Arjmandnia; Mohammad Aghaali

2013-01-01

29

The Doppler pendulum experiment  

Science.gov (United States)

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

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

2011-07-01

30

Doppler’s Effect, Gravity and Cosmology  

Directory of Open Access Journals (Sweden)

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

Sanjay M. Wagh

2013-08-01

31

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

Science.gov (United States)

Introduction: This joint US-Russian work aims to establish a methodology for assessing cardiac function in microgravity in association with manipulation of central circulating volume. Russian Braslet-M (Braslet) occlusion cuffs were used to temporarily increase the volume of blood in the lower extremities, effectively reducing the volume in central circulation. The methodology was tested at the International Space Station (ISS) to assess the volume status of crewmembers by evaluating the responses to application and release of the cuffs, as well as to modified Valsalva and Mueller maneuvers. This case study examines the use of tissue Doppler (TD) of the right ventricular (RV) free wall. Results: Baseline TD of the RV free wall without Braslet showed early diastolic E' (16 cm/s), late diastolic A' (14 cm/s), and systolic S' (12 cm/s) velocities comparable with those in normal subjects on Earth. Braslet application caused 50% decrease of E' (8 cm/s), 45% increase of A', and no change to S'. Approximately 8 beats after the Braslet release, TD showed E' of 8 cm/s, A' of 12 cm/s, and S' of 13 cm/s. At this point after release, E' did not recover to baseline values while l A' and S' did recover. The pre-systolic cross-sectional area of the internal jugular vein without Braslet was 1.07 cm 2, and 1.13 cm 2 10 min after the Braslet was applied. The respective cross-sectional areas of the femoral vein were 0.50 and 0.54 cm 2. The RV myocardial performance Tei index was calculated by dividing the sum of the isovolumic contraction time and isovolumic relaxation time by the ejection time ((IVCT+IVRT)/ET); baseline and Braslet-on values for Tei index were 0.25 and 0.22, respectively. Braslet Tei indices are within normal ranges found in healthy terrestrial subjects and temporarily become greater than 0.4 during the dynamic Braslet release portion of the study. Conclusions: TD modality was successfully implemented in space flight for the first time. TD of RV revealed that the Braslet influenced cardiac preload and that fluid was sequestered in the lower extremity interstitial and vascular space after only 10 min of application. This report demonstrates that Braslet application has an effect on RV physiology in long-duration space flight based on TD, and that this effect is in part due to venous hemodynamics.

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

2011-05-01

32

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

Science.gov (United States)

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

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

2009-01-01

33

Resonant Doppler velocimeter  

Science.gov (United States)

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

Miles, R. B.

1975-01-01

34

Research & Medical Doppler platform  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

35

Doppler Effect JS Model  

Science.gov (United States)

The Doppler Effect JS Model shows five different animations with different combinations of moving/stationary sources/detectors. The final animation shows what happens when a source exceeds the speed of sound. The Doppler Effect JS Model was developed using the Easy Java Simulations (EJS) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support. It is also distributed as an ePub.

Kennedy, Matt; Dixon, Rachel

2014-07-02

36

Determination of the Accuracy of Echocardiographic Parameters Mitral Inflow S/D Ratio and Tei Index to Detect Left Ventricular Dysfunction in Pediatric Patients with Mitral Regurgitation  

Directory of Open Access Journals (Sweden)

Full Text Available Background and Objectives: Congenital heart diseases are one of the most common anomalies in infancy. This study was performed aimed to determine the accuracy, sensitivity and specificity of the left ventricular Tei index (TX and the systolic to diastolic duration ratio (S/D to detect ventricular dysfunction in pediatric pediatrics with congenital heart defect accompanied by mitral regurgitation.Methods: In this study, systolic and diastolic function of left ventricle was evaluated by TX and S/D ratio parameters in 66 children with mitral regurgitation (34 children with normal ventricular function and 32 patients with ventricular dysfunction and the results were compared to the findings of echocardiography. Tei index>0.5 was defined as abnormal.Results: The accuracy, sensitivity, specificity, positive and negative predictive values of S/D ratio were obtained 89.3%, 87.5%, 91%, 90% and 88.5%, respectively and for TX, 87.8%, 87.5%, 88.2%, 87.5% and 88.2%, respectively.Conclusion: The results of this study showed that in general, accuracy, sensitivity, specificity, predictive values, and likelihood ratios of TX are less than those of S/D ratio in patients with congenital heart defect accompanied by mitral regurgitation.

Mohammad Hossein Arjmandnia

2013-02-01

37

Heterodyne Doppler global velocimetry  

Science.gov (United States)

Doppler Global Velocimetry (DGV) is an imaging flow measurement technique which allows the measurement of the velocity distribution in a plane. In DGV the frequency shift of scattered light from moving particles within the flow is used to determine the local flow velocity. Heterodyne Doppler Global Velocimetry (HDGV) is a new approach which combines the imaging and geometrical characteristics of DGV with the measurement principles of reference beam laser Doppler anemometry. The frequency shifted scattered light from the flow tracers is heterodyned with a reference beam from the same light source. Due to interference the result of this superposition is a harmonic intensity modulated signal. This signal is detected using a smart pixel detector array to obtain the velocity distribution. Two different experiments are presented. The first experiment compares the measured velocity distribution of a rotating disk with its actual velocity. The second experiment demonstrates the capability of the technique to measure a real flow.

Meier, Alexander H.; Roesgen, Thomas

2009-10-01

38

Pulse Doppler radar  

CERN Document Server

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

Alabaster, Clive

2012-01-01

39

Photonic doppler velocimetry  

International Nuclear Information System (INIS)

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

40

Doppler Free Laser Spectroscopy  

Science.gov (United States)

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

2012-01-09

 
 
 
 
41

Ejs Doppler Effect Model  

Science.gov (United States)

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

Aguirregabiria, Juan

2008-08-20

42

Doppler-musical instrument  

International Nuclear Information System (INIS)

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

43

Automated measurement of fetal myocardial performance index in ultrasound Doppler waveforms  

Science.gov (United States)

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

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

2014-03-01

44

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

45

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.

46

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

47

Doppler optical coherence tomography.  

Science.gov (United States)

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 importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A common problem with the technique is that the Doppler angle is not known and several approaches have been realized to obtain absolute velocity and flow data from the retina. Additional studies are required to elucidate which of these techniques is most promising. In the recent years, however, several groups have shown that data can be obtained with high validity and reproducibility. In addition, several groups have published values for total retinal blood flow. Another promising application relates to non-invasive angiography. As compared to standard techniques such as fluorescein and indocyanine-green angiography the technique offers two major advantages: no dye is required and depth resolution is required is provided. As such Doppler OCT has the potential to improve our abilities to diagnose and monitor ocular vascular diseases. PMID:24704352

Leitgeb, Rainer A; Werkmeister, René M; Blatter, Cedric; Schmetterer, Leopold

2014-07-01

48

Laser Doppler diagnostics for orthodontia  

Science.gov (United States)

The results of statistical analysis of Doppler spectra of intensity fluctuations of light, scattered from mucous membrane of oral cavity of healthy volunteers and patients, abused by the orthodontic diseases, are presented. Analysis of Doppler spectra, obtained from tooth pulp of patients, is carried out. New approach to monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of Doppler measuring system on formation of the output signal is studied.

Ryzhkova, Anastasia V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Ulyanov, Sergey S.; Lepilin, Alexander V.; Kharish, Natalia A.

2004-06-01

49

Laser Doppler velocimetry primer  

Science.gov (United States)

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

Bachalo, William D.

1985-01-01

50

STEM Colorado: Doppler Shift  

Science.gov (United States)

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

Mccray, Richard; Koelemay, Andrew

2008-08-30

51

Comparisons between PW Doppler system and enhanced FM Doppler system  

DEFF Research Database (Denmark)

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

Wilhjelm, Jens E.

1995-01-01

52

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

International Nuclear Information System (INIS)

cating 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.)

53

A Multimodal Approach to Image-Derived Input Functions for Brain PET.  

Science.gov (United States)

Many methods have been proposed for generating an image-derived input function (IDIF) exclusively from PET images. The purpose of this study was to assess the viability of a multimodality approach utilizing registered MR images. 3T-MR and HRRT-PET data were acquired from human subjects. Segmentation of both the left and right carotid arteries was performed in MR images using a 3D level sets method. Vessel centerlines were extracted by parameterization of the segmented voxel coordinates with either a single polynomial curve or a B-spline curve fitted to the segmented data. These centerlines were subsequently re-registered to static PET data to maximize the accurate classification of PET voxels in the ROI. The accuracy of this approach was assessed by comparison of the area under the curve (AUC) of the IDIF to that measured from conventional automated arterial blood sampling.Our method produces curves similar in shape to that of blood sampling. The mean AUC ratio of the centerline region was 0.40±0.19 before re-registration and 0.69±0.26 after re-registration. Increasing the diameter of the carotid ROI produced a smooth reduction in AUC. Thus, even with the high resolution of the HRRT, partial volume correction is still necessary. This study suggests that the combination of PET information with MR segmented regions will demonstrate an improvement over regions based solely on MR or PET alone. PMID:20607124

Fung, Edward K; Planeta-Wilson, Beata; Mulnix, Tim; Carson, Richard E

2009-10-24

54

Laser Doppler Imaging of Microflow  

CERN Document Server

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

Gross, Michel; Leng, Jacques

2013-01-01

55

Doppler global velocimetry  

Science.gov (United States)

A new program to develop a Doppler Global Velocimeter (DGV) for application in the High angle-of-Attack Technology Program is discussed. The Flight research instrument system will make non-intrusive multicomponent velocity measurements of the vortical flow field around an aircraft in flight. The DGV will provide a means to obtain airborne experimental data to evaluate and refine computational fluid dynamic models and to correlate with wind-tunnel data sets. The primary use of the instrument system will be to provide a flexible research tool to map the 3D velocity field at various locations around an aircraft during high angle-of-attack maneuvers at subsonic, transonic, and supersonic speeds. Other potential applications may include shock definition and interactions, external stores flow interactions, rotary flow field definition, non-steady flow field definition, measurement of inlet and duct flow field, and measurement of hypersonic flow field in flight.

Usry, Jim

1991-01-01

56

Visualizing the Doppler Effect  

Directory of Open Access Journals (Sweden)

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

Marcos H. Giménez

2008-01-01

57

Visualizing the Doppler Effect  

CERN Document Server

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

Gimenez, M H; Riera, J; Vidaurre, A; Gimenez, Marcos H.; Monsoriu, Juan A.; Riera, Jaime; Vidaurre, Ana

2007-01-01

58

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-04-15

59

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

International Nuclear Information System (INIS)

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

60

Image derived input functions for dynamic High Resolution Research Tomograph PET brain studies.  

Science.gov (United States)

The High Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography (PET) scanner. The aim of the present study was to validate the use of image derived input functions (IDIF) as an alternative for arterial sampling for HRRT human brain studies. To this end, IDIFs were extracted from 3D ordinary Poisson ordered subsets expectation maximization (OP-OSEM) and reconstruction based partial volume corrected (PVC) OP-OSEM images. IDIFs, either derived directly from regions of interest or further calibrated using manual samples taken during scans, were evaluated for dynamic [(11)C]flumazenil data (n=6). Results obtained with IDIFs were compared with those obtained using blood sampler input functions (BSIF). These comparisons included areas under the curve (AUC) for peak (0-3.3 min) and tail (3.3-55.0 min). In addition, slope, intercept and Pearson's correlation coefficient of tracer kinetic analysis results based on IDIF and BSIF were calculated for each subject. Good peak AUC ratios (0.83+/-0.21) between IDIF and BSIF were found for calibrated IDIFs extracted from OP-OSEM images. This combination of IDIFs and images also provided good slope values (1.07+/-0.11). Improved resolution, as obtained with PVC OP-OSEM, changed AUC ratios to 1.14+/-0.35 and, for tracer kinetic analysis, slopes changed to 0.95+/-0.13. For all reconstructions, non-calibrated IDIFs gave poorer results (>61+/-34% higher slopes) compared with calibrated IDIFs. The results of this study indicate that the use of IDIFs, extracted from OP-OSEM or PVC OP-OSEM images, is feasible for dynamic HRRT data, thereby obviating the need for online arterial sampling. PMID:18707007

Mourik, Jurgen E M; van Velden, Floris H P; Lubberink, Mark; Kloet, Reina W; van Berckel, Bart N M; Lammertsma, Adriaan A; Boellaard, Ronald

2008-12-01

 
 
 
 
61

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.

62

Interstitial Doppler optical coherence tomography  

Science.gov (United States)

Doppler optical coherence tomography (OCT) can image tissue structure and blood flow at micrometer-scale resolution but has limited imaging depth. We report a novel, linear-scanning, needle-based Doppler OCT system using angle-polished gradient-index or ball-lensed fibers. A prototype system with a 19-guage (diameter of ~0.9 mm) echogenic needle is constructed and demonstrates in vivo imaging of bidirectional blood flow in rat leg and abdominal cavity. To our knowledge, this is the first demonstration of Doppler OCT through a needle probe in interstitial applications to visualize deeply situated microcirculation.

Yang, Victor X. D.; Mao, You X.; Munce, Nigel; Standish, Beau; Kucharczyk, Walter; Marcon, Norman E.; Wilson, Brian C.; Vitkin, I. Alex

2005-07-01

63

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

64

High Resolution Doppler Lidar  

Science.gov (United States)

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

1996-01-01

65

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; Jensen, JØrgen Arendt

2009-01-01

66

L wave in echo Doppler.  

Science.gov (United States)

62-year-old female presented with progressive dyspnea NYHA class III for six months. Echocardiography showed normal left ventricular (LV) systolic function, mild biatrial enlargement, an L wave in pulse wave Doppler at mitral inflow and in M mode echocardiography across mitral valve. Tissue Doppler imaging at medial mitral annulus showed an L' wave in mid diastole in addition to E' and A' wave. An L wave in pulse wave Doppler and M mode echocardiography represents continued pulmonary vein mid diastolic flow through the left atrium in to LV across mitral valve after early rapid filling. Presence of an L' wave in these patients associated with higher E/E' is indicative of advance diastolic dysfunction with elevated filling pressures. PMID:24973854

Kumar, Vipin; Jose, John; Jose, V Jacob

2014-01-01

67

Laser Doppler methods in electrophoresis  

Science.gov (United States)

Electrophoretic motion of particles, molecules, and biological cells can be readily measured by laser Doppler techniques. Small frequency shifts associated with the motion of the scatterers are detected by heterodyne detection of the scattered laser light. The principles of laser light scattering and heterodyne detection are reviewed. The central experimental problems associated with the application of electric fields to conducting solutions are considered in detail. Various types of laser Doppler spectrometers and electrophoresis chambers are compared both from fundamental physical points of view as well as in terms of resolving power of standard marker cells. As applications of the laser Doppler technique, measurements on proteins, virtues, nucleic acids, bioparticles and biological cells are reviewed.

Uzgiris, Egidijus E.

68

Doppler Ultrasound Doppler and their applications in maternal medicine  

International Nuclear Information System (INIS)

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

69

The micro-doppler effect in radar  

CERN Document Server

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

Chen, Victor

2011-01-01

70

A generic Doppler feedback model  

International Nuclear Information System (INIS)

A new method has been developed for obtaining the Doppler feedback correction to the absorption cross section for off-reference power conditions. Second-order factors have been derived to extend the methodology to all Westinghouse fuel and burnable absorber types and soluble boron conditions. The method eliminates the need for multiple cross-section calculations at various power levels, while providing results of comparable accuracy

71

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

72

General principles of carotid Doppler ultrasonography  

Directory of Open Access Journals (Sweden)

Full Text Available

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

Whal Lee

2014-01-01

73

Detection of microemboli by transcranial Doppler ultrasound.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1996-01-01

74

Doppler principle - inspiration of modern physics  

International Nuclear Information System (INIS)

The Doppler principle not only represents a useful experimental method of velocity measurement in many fields of science and technology, it is deeply embedded in the foundations of modern relativistic and quantum physics. The discovery of the anomalous Doppler effect exactly 50 years ago and the development of microwave electronics, laser techniques and plasma physics made possible new extensive applications and a deeper understanding of the Doppler principle; this is true especially in the case of supersonic and supraluminous motions. Also, the Einstein quantum theory of radiation has been modified by including new types of quantum transitions closely related to the Doppler effect. (author) 12 refs

75

Pulsed-Doppler ultrasonic arteriography  

International Nuclear Information System (INIS)

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

76

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Science.gov (United States)

...2010-04-01 2010-04-01 false Ultrasonic pulsed doppler imaging system...Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging system. (a) Identification. An ultrasonic pulsed doppler imaging...

2010-04-01

77

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

78

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

79

Color doppler sonography in thickened gallbladder wall  

International Nuclear Information System (INIS)

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

80

Color doppler sonography in thickened gallbladder wall  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-11-01

 
 
 
 
81

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

82

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

83

Color doppler imaging of subclavian steal phenomenon  

Energy Technology Data Exchange (ETDEWEB)

To evaluate the characteristic color doppler imaging of vertebral artery flow in the subclavian steal phenomenon. The study group consisted of eight patients with reversed vertebral artery flow proved by color Doppler imaging. We classified this flow into two groups:(1) complete reversal;(2) partial reversal, as shown by Doppler velocity waveform. Vertebral angiography was performed in six of eight patients;color Doppler imaging and angiographic findings were compared. On color Doppler imaging, all eight cases with reversed vertebral artery flow showed no signal at the proximal subclavian or brachiocephalic artery. We confirmed shunting of six cases by performing angiography from the contralateral vertebral and basilar artery to the ipsilateral vertebral artery. On the Doppler spectrum, six cases showed complete reversal and two partial reversal. On angiography, one partial reversal case showed complete occlusion of the subclavian artery with abundant collateral circulation of muscular branches of the vertebral artery. On color Doppler imaging, a reversed vertebral artery suggests the subclavian steal phenomenon. In particular, partial reversal waveform may reflect collateral circulation.

Cho, Nari Ya; Chung, Tae Sub; Kim, Jai Keun [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)

1997-03-01

84

Color doppler imaging of subclavian steal phenomenon  

International Nuclear Information System (INIS)

To evaluate the characteristic color doppler imaging of vertebral artery flow in the subclavian steal phenomenon. The study group consisted of eight patients with reversed vertebral artery flow proved by color Doppler imaging. We classified this flow into two groups:(1) complete reversal;(2) partial reversal, as shown by Doppler velocity waveform. Vertebral angiography was performed in six of eight patients;color Doppler imaging and angiographic findings were compared. On color Doppler imaging, all eight cases with reversed vertebral artery flow showed no signal at the proximal subclavian or brachiocephalic artery. We confirmed shunting of six cases by performing angiography from the contralateral vertebral and basilar artery to the ipsilateral vertebral artery. On the Doppler spectrum, six cases showed complete reversal and two partial reversal. On angiography, one partial reversal case showed complete occlusion of the subclavian artery with abundant collateral circulation of muscular branches of the vertebral artery. On color Doppler imaging, a reversed vertebral artery suggests the subclavian steal phenomenon. In particular, partial reversal waveform may reflect collateral circulation

85

Doppler sonography of the native liver  

International Nuclear Information System (INIS)

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

86

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

87

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

88

Preliminary simulation study of doppler reflectometry  

International Nuclear Information System (INIS)

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

89

The use of two-dimensional Doppler sonography (color Doppler) in the diagnosis of hydranencephaly.  

Science.gov (United States)

Hydranencephaly, first described by Cruveilhier, may be defined as a rare condition in which the cerebral hemispheres are replaced by membranous sacs filled with cerebrospinal fluid. Cerebral angiography is especially useful in differentiating hydranencephaly and severe hydrocephalus, massive subdural hygromas and alobar holoprosencephaly, but it is no better than other neuroradiological diagnosis methods in the neonate. This report outlines the diagnostic use of two-dimensional Doppler (color Doppler) in a child with hydranencephaly. Color Doppler was performed using an SSA-270A (Toshiba) with a 3.75 MHz phase-array sector scanning probe and no sedation. In this study, color Doppler demonstrated the internal carotid artery in the proximal portion, but the secondary and tertiary branches were not observed. In summary, color Doppler permitted early, easy diagnosis of hydranencephaly. In addition, the use of color Doppler was beneficial in diagnosing other anomalies of the central nervous system in neonates. PMID:2095306

Doi, H; Tatsuno, M; Mizushima, H; Matsumoto, K

1990-12-01

90

The MSFC Doppler lidar system, appendix B  

Science.gov (United States)

The development of pulsed and continuous wave Doppler lidars for atmospheric measurement is discussed. A description of how the lidar systems operate is presented. The scanning mode is also described.

Bilbro, J. W.; Krause, M. C.

1980-01-01

91

Doppler coefficient measurements in Zebra Core 5  

International Nuclear Information System (INIS)

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

92

Laser Doppler flowmeter measures gas velocity  

Science.gov (United States)

Utilizing the large magnitudes of Doppler shifts obtainable from a CW gas laser, local velocity vectors are measured by using the visible light from the laser. This technique is applicable for the measurement of velocity of any moving surface.

Foreman, W.; Huffaker, R. M.

1966-01-01

93

Evaluation of a pulsed ultrasonic Doppler flowmeter  

Science.gov (United States)

The in vivo application of the pulsed ultrasound Doppler velocity meter (PUDVM) for measuring arterial velocity waveforms is reported. In particular, the performance of the PUDVM is compared with a hot film anemometer of proven accuracy.

Wells, M. K.

1973-01-01

94

Doppler Imaging of Exoplanets and Brown Dwarfs  

CERN Document Server

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

Crossfield, Ian J M

2014-01-01

95

An overview of Doppler global velocimetry  

Science.gov (United States)

Doppler global velocimetry (DGV), currently undergoing development at NASA-Langley, obtains velocity measurements by identifying the Doppler frequency of laser light that is scattered by submicronic particles moving within the flow. An effort is here made to predict DGV's measurement capabilities and envision plausible applications. Attention is given to frequency discrimination, illumination and seeding nonuniformities, velocity component resolution capabilities, and attainable levels of temporal and spatial resolution.

Miller, L. S.

1992-10-01

96

The Doppler Wind and Temperature Sounder  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Doppler Wind and Temperature Sounder (DWTS) is novel sensor concept for measuring global winds and temperatures from cloud-top to the thermosphere. This will significantly improve medium- and long-range weather forecasts and enable more advanced tracking of severe storms. The approach uses the inherent high spectral resolution from gas filter correlation radiometry to simultaneously measure the Doppler shift and linewidth of limb emission spectra as viewed from low-Earth orbit. DWTS im...

Mchugh, Martin; Fritts, Dave; Gordley, Larry

2014-01-01

97

Borescopic Laser Doppler Velocimetry probe  

Science.gov (United States)

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

O'Brien, Kory T.

98

Doppler synthetic aperture hitchhiker imaging  

International Nuclear Information System (INIS)

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

99

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

100

Estimation of the continuously varying Doppler effect  

Science.gov (United States)

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

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

2010-04-01

 
 
 
 
101

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.

102

Retroreflector for photonic Doppler velocimetry  

Science.gov (United States)

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

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

2009-08-01

103

Doppler evaluation of valvular regurgitation  

International Nuclear Information System (INIS)

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

104

Doppler Imaging of Exoplanets and Brown Dwarfs  

Science.gov (United States)

Doppler Imaging produces 2D global maps. When applied to cool planets or more massive brown dwarfs, it can map atmospheric features and track global weather patterns. The first substellar map, of the 2pc-distant brown dwarf Luhman 16B (Crossfeld et al. 2014), revealed patchy regions of thin & thick clouds. Here, I investigate the feasibility of future Doppler Imaging of additional objects. Searching the literature, I find that all 3 of P, v sin i, and variability are published for 22 brown dwarfs. At least one datum exists for 333 targets. The sample is very incomplete below ~L5; we need more surveys to find the best targets for Doppler Imaging! I estimate limiting magnitudes for Doppler Imaging with various hi-resolution near-infrared spectrographs. Only a handful of objects - at the M/L and L/T transitions - can be mapped with current tools. Large telescopes such as TMT and GMT will allow Doppler Imaging of many dozens of brown dwarfs and the brightest exoplanets. More targets beyond type L5 likely remain to be found. Future observations will let us probe the global atmospheric dynamics of many diverse objects.

Crossfield, I.; Biller, B.; Schlieder, J.; Deacon, N.; Bonnefoy, M.; Homeier, D.; Allard, F.; Buenzli, E.; Henning, T.; Brandner, W.; Goldman, Bertr; Kopytova, T.

2014-03-01

105

Duplex doppler sonography in portal hypertension  

Directory of Open Access Journals (Sweden)

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

Ni?iforovi? Dijana

2007-01-01

106

Uteroplacental Doppler ultrasound in routine antenatal care.  

Science.gov (United States)

Three hundred and five pregnant women referred consecutively from a single antenatal clinic for imaging ultrasound after 26 weeks' gestation had doppler velocimetry of umbilical artery, uterine artery and umbilical vein. Results of doppler studies were not available to clinicians until after delivery and clinical case records were examined postpartum for the development of pregnancy-induced hypertension (PIH) or gestational diabetes mellitus (DM) and for fetal outcome. Accurate data were available for 272 women, of whom 167 had a normal pregnancy, 61 had or developed PIH and 44 had or developed DM. None of the various doppler velocimetry measurements differed significantly amongst these 3 groups at any gestational stage. Abnormal values for doppler systolic: diastolic (A/B) ratio were found in only 7% of umbilical artery measurements, 6% of uterine artery measurements and none of umbilical vein measurements. Specificity of abnormal results for PIH or DM was high (95-97%) but sensitivity low (16-17%) and positive and negative predictive values were generally low. Two perinatal deaths occurred and umbilical artery A/B ratio was abnormal in both cases. This study shows that there is a low yield of abnormal results for doppler velocimetry of umbilical artery, uterine artery or umbilical vein in routine antenatal screening. PMID:2082883

Brown, M A; North, L; Hargood, J

1990-11-01

107

Applications of Doppler ultrasound during labor.  

Science.gov (United States)

The information provided by Doppler ultrasound examination during labor permits the understanding of the mechanisms regarding the physiology and pathophysiology of feto-placental exchange and the fetal adaptive systems. There are certain technical difficulties related to intrapartum Doppler ultrasound examination. The investigated sites are the uterine arteries, umbilical arteries, fetal circulation. In diastole, when intrauterine pressure exceeds maternal diastolic pressure, the perfusion pressure of the uterine artery blood flow is no longer present. A progressive decrease in the diastolic component is seen along with an increase in intrauterine pressure from 10 to 60 mmHg. During premature birth or preeclampsia, there are particular changes in the uterine blood flow. A remarkable stability of the umbilical resistance index is found during labor, which shows the permanent presence of feto-placental exchange. Certain correlations can be established between fetal heart rate changes in labor and Doppler ultrasound aspects at the level of umbilical arteries. Doppler examination confirms the concept of reduced cerebral blood flow by the compression of the fetal skull as a cause of decelerations occurring during labor. The decision regarding the extraction of the fetus can only be made by correlating the results of Doppler ultrasound with the other paraclinical methods for the monitoring of the intrapartum fetal status. PMID:21655541

Mihu, Dan; Diculescu, Doru; Costin, Nicolae; Mihu, Carmen Mihaela; Blaga, Ligia; Ciortea, R?zvan; M?lu?an, Andrei

2011-06-01

108

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

109

Doppler Simulation and Analysis of SCME Channel Model  

Directory of Open Access Journals (Sweden)

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

Xiaoyan Huang

2012-10-01

110

Diabetic Nephropathy : Evaluation with Doppler Ultrasonography  

Energy Technology Data Exchange (ETDEWEB)

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

Sim, Jung Suk; Kim, Seung Hyup; Kang, Heung Sik; Park, Jae Hyung; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

1996-06-15

111

Color Doppler ultrasonography evaluation of amblyopia  

Directory of Open Access Journals (Sweden)

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

Ece Turan-Vural

2013-07-01

112

Hydrogen doppler spectroscopy using 15N ions  

Science.gov (United States)

The energy spread of atomic and molecular ion beams from the 4 MV Dynamitron tandem accelerator at the Ruhr-Universität Bochum has been studied and in part minimized. Using the ER= 6.40 MeV narrow resonance in 1H(15N,??)12C with an 15N energy spread of 4.55 keV, the Doppler broadening for several hydrogen-bearing gases was found to be in good agreement with expectation: e.g. for NH3 gas a rotational-vibrational Doppler width of 10.41 +/- 0.25 keV was observed (theory = 10.4 keV). Studies of the vibrational Doppler widths of H-bonds on a Si surface were performed using a 4??-ray detection system together with UHV-chambers for sample preparation, transport, and analysis. The results showed that further improvements in the experimental set-ups are needed for such investigations.

Borucki, L.; Becker, H. W.; Gorris, F.; Kubsky, S.; Schulte, W. H.; Rolfs, C.

113

Doppler optomechanics of a photonic crystal.  

Science.gov (United States)

A laser beam directed at a mirror attached onto a flexible mount adds friction to its mechanical motion by the Doppler effect. For a normal mirror the efficiency of this radiative Doppler friction is very weak and practically masked by laser shot noise. We find that it can become very efficient using a photonic crystal mirror near its photonic band gaps. As an example, a Bragg mirror used at the long wavelength edge of its band stop can be efficiently optically cooled using the Doppler friction. The opposite effect opens new routes for optical pumping of mechanical systems: a laser pointing at a Bragg mirror and tuned at its short wavelength edge induces amplification of the vibrational excitation of the mirror leading eventually to its self-oscillation. These new effects rely on the strong dependency of a photonic crystal reflectivity on the wavelength. PMID:18643566

Karrai, K; Favero, I; Metzger, C

2008-06-20

114

Diabetic Nephropathy : Evaluation with Doppler Ultrasonography  

International Nuclear Information System (INIS)

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

115

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

116

Aortic coartation. Diagnostic by renal arteries Doppler  

International Nuclear Information System (INIS)

Aortic coartaction is an important and treatable cause of hypertension. The diagnosis is suspected by the physician and can be confirmed or be suggested by the radiologist because many of these patients are referred for Doppler looking to exclude renal artery stenosis as a cause of hypertension. Tardus-parvus pattern in both renal arteries in combination with an alteration of the waveform in the abdominal aorta strongly suggests the diagnosis. We report three cases in young patients with symptomatic arterial hypertension and alteration in the morphology of the spectral waves demonstrated by Doppler of renal arteries that suggest the diagnosis of aortic coartaction, which is confirmed by CT, echocardiography and aortography

117

21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.  

Science.gov (United States)

... Ultrasonic pulsed doppler imaging system. 892.1550 Section 892.1550 Food and Drugs FOOD AND DRUG ADMINISTRATION... RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging system....

2010-04-01

118

Comparison of power Doppler and color Doppler ultrasonography in the detection of intrasticular blood flow of normal infants  

International Nuclear Information System (INIS)

To compare color Doppler ultrasonography (US) and power Doppler US in the detection of intratesticular blood flow in normal infants and to asses the symmetry of blood flow. Testicular blood flow was assessed prospectively in 100 testes of 50 infants with both power and color Doppler US. We compared the power Doppler with color Doppler to detect intratesticular blood. When the flow was detected, intratesticular blood flow was graded as follows: grade 1: single intratesticular Doppler signal ; grade 2: multiple intratesticular Doppler signals. The symmetry of intratesticular flow was assessed by using the same method. Intratesticular flow was detected in 72 (72%) and 68 (68%) testes on power and color Doppler US, respectively. In 76 testes (76%), intratesticular flow was detected in either one or both techniques. On power Doppler US, grade 1 was seen in 40 tests and grade 2 in 32 testes. On color Doppler US, grade 1 was noted in 52 testes and grade 2 in 16 testes. Testicular blood flow was symmetric on both power and color Doppler US in each patient. There was no difference between power Doppler and color Doppler ultrasonography in detecting intratesticular blood flow in normal infants.

119

A compact, laser diode based phase Doppler system  

Science.gov (United States)

Recent advances in laser diode technology provide the opportunity to reduce the size and cost of laser Doppler and phase Doppler anemometry systems. The application of laser diodes to phase Doppler systems is discussed, and the construction of a compact, laser diode based Doppler system is described. Test measurements in a monosized drop stream, a water spray and a fluidized bed are reported, demonstrating the functionality of such a system.

Sellens, R. W.

1990-05-01

120

Atmospheric laser Doppler velocimetry - An overview  

Science.gov (United States)

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

Bilbro, J. W.

1980-01-01

 
 
 
 
121

The Bell Laboratories Moessbauer effect Doppler modulator  

International Nuclear Information System (INIS)

This paper describes briefly the Doppler modulator used at Bell Laboratories to provide a means of shifting the energy of nuclear gamma rays by a precisely controlled amount. This makes it possible to examine regions of the spectrum in the vicinity of nuclear transition energies. 2 refs, 4 figs

122

Power Doppler sonography of cervical lymphadenopathy  

International Nuclear Information System (INIS)

AIMS: The supraclavicular region is a common site for tuberculous and metastatic nodes from infraclavicular carcinomas. Grey scale sonographic features differentiating the two have been previously described. However, as power Doppler sonography is now frequently used in the assessment of neck nodes, power Doppler features that may help to differentiate the two are discussed. MATERIALS AND METHODS: In 78 patients, power Doppler sonograms of nodes involved by metastases from infraclavicular carcinomas (n = 24) and tuberculosis (n = 54) were evaluated. The intranodal distribution of vessels and the intranodal vascular resistance of vessels was assessed and compared. In addition, the power Doppler features of metastatic nodes from infraclavicular carcinomas were compared with metastatic nodes from a head and neck primary (n = 38) such as nasopharyngeal carcinoma (NPC). RESULTS: Tuberculous nodes frequently demonstrated displaced hilar vascularity or avascularity and the intranodal vascular resistance was low. Metastatic nodes from infraclavicular primaries demonstrated capsular or mixed vascularity and their intranodal resistance was significantly (P < 0.05) higher. In general, metastatic nodes from infraclavicular primaries had a higher intranodal vascular resistance compared to metastatic nodes from NPC, but this was not statistically significant. CONCLUSION: In the supraclavicular region, the presence of displaced low resistance hilar vascularity or avascularity in nodes is suggestive of tuberculous nodes. Metastatic nodes from infraclavicular primaries have a capsular or mixed vascularity with high resistance. Ahuja, A. et al. (2001)

123

Ultrasonic Doppler color in glaucoma: Concordance study  

International Nuclear Information System (INIS)

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

124

The Doppler Effect and Sonic Booms  

Science.gov (United States)

This web page provides animations that show the physics of the Doppler effect and the formation of shockwaves from sound waves generated by a moving source. Photos show shockwaves of a bullet, an airplane, and a supersonic land vehicle. Links provide further information.

2007-07-01

125

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

126

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

127

Preoperative Doppler assessment for transmetatarsal amputation.  

Science.gov (United States)

A thorough preoperative vascular evaluation should be performed before the initiation of any lower extremity surgical intervention, but particularly in situations of diabetic foot reconstruction with compromised blood flow. The intended emphasis of this brief report is to provide the foot and ankle surgeon with an appreciation for the clinical vascular anatomy of the transmetatarsal amputation through a handheld Doppler examination. PMID:20123301

Attinger, Christopher E; Meyr, Andrew J; Fitzgerald, Sarah; Steinberg, John S

2010-01-01

128

An Audit of a Hospital-Based Doppler Ultrasound Quality Control Protocol Using a Commercial String Doppler Phantom  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Cournane, S.; Fagan, A. J.; Browne, Jacinta

2014-01-01

129

A comprehensive two-way Doppler noise model for near-real-time validation of Doppler data  

Science.gov (United States)

Doppler noise generated within the tracking system is modeled as a function of the dominant variable-Doppler sample interval. Additionally, the relationship between media noise and Doppler samples interval is empirically determined, and the ratio of media noise for S- and X-band downlinks is solved for. These functional relationships are incorporated into the previous media noise modeling to obtain a comprehensive two-way Doppler noise model.

Berman, A. L.

1977-01-01

130

Doppler speedometer for micro-organisms  

International Nuclear Information System (INIS)

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

131

Doppler imaging of exoplanets and brown dwarfs  

Science.gov (United States)

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

Crossfield, Ian J. M.

2014-06-01

132

Carotid Artery Doppler Assessment In Patients Accussed Of Strokes  

Directory of Open Access Journals (Sweden)

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

H. Mazaher

2005-08-01

133

Doppler-spectrally encoded imaging of translational objects  

Science.gov (United States)

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

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

2014-05-01

134

Minior Actinide Doppler Coefficient Measurement Assessment  

International Nuclear Information System (INIS)

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

135

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

136

ESTADO ACTUAL DEL ULTRASONIDO DOPPLER CAROTÍDEO  

Directory of Open Access Journals (Sweden)

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

H\\u00E9ctor Pereira Recio

2007-01-01

137

Renal duplex Doppler ultrasound findings in diabetics  

Energy Technology Data Exchange (ETDEWEB)

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

Shim, Hyang Yee; Kim, Young Geun; Kook, Cheol Keu; Yoon, Chong Hyun; Lee, Shin Hyung; Lee, Chang Joon [National Medical Center, Seoul (Korea, Republic of)

1993-12-15

138

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

139

The Doppler spread theory and parameterization revisited  

Science.gov (United States)

The author's earlier Doppler Spread Theory (DST) and Doppler Spread Parameterization (DSP) are revisited with a new understanding of the dichotomous roles played by nonlinearity in Eulerian and Lagrangian coordinates, respectively. An embryo Lagrangian DST is introduced and employed to assess the original DST. Earlier results near the Eulerian spectral peak are found to be reasonably valid, whereas those at greater vertical wavenumber are confirmed to have produced too much spreading. The earlier DSP is found to need little if any change, though specific values are suggested for its two most important ``fudge factors''. In a more general context, the continuing identity of a wave undergoing certain nonlinear interactions with other waves is discussed.

Hines, Colin O.

2004-07-01

140

Doppler cooling three-electronic-level molecules  

CERN Document Server

Analogous to the extension of laser cooling techniques from two-level to three-level atoms, Doppler cooling of molecules with an intermediate electronic state is considered. In particular, we use a rate-equation approach to simulate cooling of SiO+, in which population buildup in the intermediate state is prevented by its short lifetime. We determine that Doppler cooling of SiO+ can be accomplished without optically repumping from the intermediate state, at the cost of causing undesirable parity flips and rotational diffusion. Since the necessary repumping would require a large number of continuous-wave lasers, optical pulse shaping of a femtosecond laser is proposed as an attractive alternative. Other candidate three-electron-level molecules are also discussed.

Nguyen, J H V

2010-01-01

 
 
 
 
141

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

142

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.)

143

Applications of Doppler optical coherence tomography  

Science.gov (United States)

A major development in biomedical imaging in the last decade has been optical coherence tomography (OCT). This technique enables microscale resolution, depth resolved imaging of the detailed morphology of transparent and nontransparent biological tissue in a noncontact and quasi-noninvasive way. In the first part of this dissertation, we will describe the development and the performance of our home-made OCT systems working with different wavelength regions based on free-space and optical fiber Michelson interferometers. The second part will focus on Doppler OCT (DOCT), an important extension of OCT, which enables the simultaneous evaluation of the structural information and of the fluid flow distribution at a localized position beneath the sample surface. Much effort has been spent during the past few years in our laboratory aimed at providing more accurate velocity measurements with an extended dynamic range. We also applied our technique in different research areas such as microfluidics and hemodynamics. Investigations on the optical properties of the biological tissues (such as absorption and scattering) corresponding to different center wavelengths, have been performed in our laboratory. We used a 10 femtosecond Ti:sapphire laser centered at about 810 nm associated with a free-space Michelson interferometer. The infrared sources were centered at about 1310 and 1560 nm with all-fiber interferometers. Comparative studies using three different sources for several in vitro biological tissues based on a graphical method illustrated how the optical properties affect the quality of the OCT images in terms of the penetration depth and backscattering intensity. We have shown the advantage of working with 810-nm emission wavelength for good backscattering amplitude and contrast, while sources emitting at 1570 nm give good penetration depth. The 1330-nm sources provide a good compromise between the two. Therefore, the choice of the source will ultimately determine the longitudinal resolution and the imaging depth for OCT imaging. Doppler OCT is becoming an increasingly popular field of investigation within optical coherence tomography with potentially important applications in cardiovascular and microfluidic research. We have spent some of the effort on searching for accurate and efficient methods for processing the experimental data. We applied the pseudo Wigner time-frequency distribution method to the data processing of Doppler OCT and compared its performance to that of the short-time Fourier transform method, the Hilbert-based phase-resolved method and the autocorrelation method. We concluded that the pseudo Wigner-distribution signal processing method is overall more precise than other often-used methods in Doppler OCT for the analysis of cross-sectional velocity distributions, especially in the high velocity regime. We also discovered the advantage of using the time-domain instead of the frequency domain for Doppler OCT for some applications where precise Doppler-speed metrology is essential. Based on the fact that the obtained local OCT interference signal is almost a single periodic waveform, we have developed a novel, simple and less time-consuming processing method based on the zero-crossing points in an OCT signal for the measurement of the Doppler frequency in a laminar flow. This method was compared to other processing approaches currently used in Doppler OCT. The results show that in the case of laminar flow, the zero-crossing method gives the more precise results, especially in the higher velocity regime with a substantial economy in processing time and an increase in dynamic range which can reach 70 dB. This feature becomes a major advantage in metrology if one wants to measure velocities over several orders of magnitude. We have applied this technique to some real flow models and the preliminary results on flow velocity distributions obtained in the case of a microfluidic circuit and in that of a phantom of a blood vessel stenosis and bifurcation will be described in this thesis. We also proposed the method to

Xu, Zhiqiang

144

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

145

Windfield retrieval from Doppler lidar observations  

Science.gov (United States)

An approach to the retrieval of a vector wind field from Doppler lidar observations is developed in general terms. The field of radial velocity measurements from each look angle is modeled by a smooth surface, the parameters of the model being determined from the data by least squares techniques. The vector wind field and higher order fields are obtained from the two modeled surfaces. Estimated measurement errors are taken into account, and error estimates are available for all output data sets.

Lee, R. W.

1980-01-01

146

Colour Doppler ultrasound of the penis  

Energy Technology Data Exchange (ETDEWEB)

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

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

2003-07-01

147

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

148

A Doppler flowmeter for use in theatre.  

Science.gov (United States)

We have developed a Doppler flowmeter based on a 10 MHz pencil probe and mean frequency estimator which overcomes many of the limitations of existing electromagnetic and ultrasonic flowmeters. The output of the flowmeter, which is proportional to the first moment of the Doppler power spectrum and hence mean blood velocity is linear from 1.3 to over 50 cm s-1 for pulsatile flow. Variation in vessel diameter and angle of insonation, which are the common sources of error in Doppler flowmetry, are minimised by constraining the vessel in a plastic cuff which fixes the probe angle at 50 degrees. A simple gauge is used to compress the vessel flat, before the cuff is applied, to measure the wall thickness to within 0.25 mm. The vessel internal diameter and hence blood flow can then be calculated using an experimentally determined calibration factor to compensate for non-even insonation. A range of sterilizable cuffs from 3-12 mm diameter have been built and the flowmeter is now being used routinely during all arterial reconstructive surgery. The accuracy and reproducibility of the system was tested for range of different sized silastic tubes on a hydraulic model and found to be less than 12% for vessels greater than 2 mm internal diameter. Satisfactory signals were easily obtained from all prosthetic materials with the exception of PTFE. The instantaneous output was compared to an electromagnetic flowmeter using a fast Fourier transform algorithm; the moduli of the harmonics were virtually identical but the Doppler system produced a smaller phase shift with increasing harmonics.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2949415

Beard, J D; Evans, J M; Skidmore, R; Horrocks, M

1986-11-01

149

Doppler, Johann Christian Andreas (1803-53)  

Science.gov (United States)

Born in Salzburg, Austria, Doppler studied and taught mathematics in Vienna. On the verge, because of economic hardship, of emigrating to America, he was offered posts in Prague. Despite huge teaching loads, he was able to carry out some research of his own (in the face of complaints of neglect by his students). In 1842 read a paper to the Royal Bohemian Society `On the colored light of the doubl...

Murdin, P.

2000-11-01

150

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

Directory of Open Access Journals (Sweden)

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

Cibele Figueira Carvalho

2008-06-01

151

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

Scientific Electronic Library Online (English)

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

Cibele Figueira, Carvalho; Maria Cristina, Chammas; Giovanni Guido, Cerri.

152

Optimization of cw-QC lasers for Doppler and sub-Doppler molecular spectroscopy  

Science.gov (United States)

Inter-subband (Type I) quantum-cascade (QC) lasers have shown the potential to generate tunable mid-IR radiation with narrow intrinsic linewidths (optical configurations which preclude significant optical feedback and need for stringent mode coupling alignments, the cw-DFB-QC lasers show great promise to do high resolution sub-Doppler spectroscopy. By serendipitous events, a varient of 'mode- or level-crossing' spectroscopy was probably rediscovered, which may allow very high resolution, sub-Doppler features and/or hyperfine alignments to be probed with 'uni-directional' topologies. We will primarily discuss the basic features of the 'uni-directional' sub-Doppler spectroscopy concept in this report. It shows potential to be exploitable in multi-pass cells or ring configurations. The phenomena of satuation 'dips' in molecular transitions appear to be very accessible with sinusoidally current-modulated DFB-QC lasers. Observations of sub-Doppler structures, either induced by residual AM 'pulsation dips' and/or hyperfine level-crossing effects (due to weak Zeeman splittings by the earth's B-field) can be recovered with good contrast. If this phenomena is indeed implicated with long-lived coherent hyperfine alignments, due perhaps to coherent population trapping in 'dark-states,' then sub-Doppler signals from saturated 'level-crossings' can potentially be seen without recourse to expensive polarization optics, nor elaborate beam shaping and isolation techniques.

Kelly, James F.; Disselkamp, Robert S.; Sams, Robert L.; Blake, Thomas A.; Sharpe, Steven W.; Richter, Dirk A.; Fried, Alan

2002-09-01

153

Anomalous Doppler effect in microwave devices  

International Nuclear Information System (INIS)

The anomalous Doppler effect (ADE) is explained in close relation with the normal Doppler effect (NDE) and the Cherenkov effect (CE). The concept of waves with either negative or positive energy in an electron beam is dealt with, and the interaction of the waves with an electromagnetic wave is discussed, including the synchronization conditions for resonance energy transfer. A comparison shows that the synchronization conditions (the energy approach) are identical with relations obtained from the Doppler formulae for radiation emitted by moving electrons of the beam (the frequency approach). The case of the interaction of the electromagnetic wave with a longitudinal electron wave with positive energy corresponds to the NDE, and the case of the interaction of the electromagnetic wave with a longitudinal electron wave with negative energy corresponds to the ADE. Attention is paid to the concept of the induced ADE and of the induced NDE. Based on the theoretical results provided, a description is given of the operation of certain microwave devices (e.g. the travelling wave tube). (author) 2 figs., 11 refs

154

Imaging system considerations in Doppler global velocimetry  

Science.gov (United States)

Doppler Global Velocimetry (DGV) is a full-field optical technique for the measurement of fluid flow velocities. The flow is illuminated using a light sheet, and the Doppler shift imposed on light scattered from moving particles within the sheet is imaged through a cell containing iodine vapor onto a solid-state array camera, thereby converting the Doppler frequency shifts into intensity variations in the image. In this paper, a DGV system is presented based around an argon-ion laser source and a fast digital image-processing system, which allows the DGV velocity map to be updated at camera frame rate. Interpretation of DGV images is complicated by errors which arise at positions some way out in the field of view due to the modified illumination and viewing vectors corresponding to these positions. Typical magnitudes of such errors are calculated. Significant errors can arise for points more than about 5 degree(s) out from the center of the field of view, and for divergence angles of the illumination beam exceeding about 10 degree(s) at a distance of 5 cm from the beam axis. Other considerations affecting system accuracy are also discussed.

Ford, Helen D.; Tatam, Ralph P.

1995-09-01

155

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

156

Doppler sonographic findings in testicular microlithiasis  

Scientific Electronic Library Online (English)

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

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

2008-08-01

157

Doppler sonographic findings in testicular microlithiasis  

Directory of Open Access Journals (Sweden)

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

Selim Serter

2008-08-01

158

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

159

Pulsed and Color Doppler Sonographic Findings of Penile Mondor's Disease  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This report describes the color and pulsed Doppler US findings of penile Mondor's disease. The pulsed Doppler US findings of penile Mondor's disease have not been previously published, so we report here for the first time on the cavernosal arterial flow signal pattern of penile Mondor's disease. Penile Mondor's disease is rare disease that's characterized by thrombosis in the dorsal vein of the penis. The previous reports on penile Mondor's disease are concerned with the color Doppler US find...

Han, Hye Yeon; Chung, Dong Jin; Kim, Kum Won; Hwang, Cheol Mog

2008-01-01

160

Doppler radar wind field retrieval over the Po Valley  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2006-01-01

 
 
 
 
161

Active Region Moss: Doppler Shifts from Hinode/EIS Observations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

162

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

163

Calculation of the Doppler broadening function using Fourier analysis  

International Nuclear Information System (INIS)

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

164

Power doppler 'blanching' after the application of transducer pressure  

International Nuclear Information System (INIS)

The aim of this study was to determine if transducer pressure modifies power Doppler assessments of rheumatoid arthritis synovium at the metacarpophalangeal joints and metatarsophalangeal joints. Five rheumatoid arthritis patients of varying degrees of 'disease activity' and damage were assessed with power Doppler ultrasound scanning of the dominant hand second to fifth metacarpophalangeal joints. Two rheumatoid arthritis patients had their dominant foot first to fifth metatarsophalangeal joints assessed with power Doppler ultrasound. Ultrasonography was performed with a high frequency transducer (14 MHz) with a colour mode frequency of 10 Mhz, and a standard colour box and gain. In the joint that showed the highest power Doppler signal, an image was made. A further image was taken after transducer pressure was applied. In all patients, there was increased flow to at least one joint. After pressure was applied, power Doppler signal intensity markedly reduced in all images and in some there was no recordable power Doppler signal. Increased transducer pressure can result in a marked reduction or obliteration in power Doppler signal. This power Doppler 'blanching' shows the need for further studies to evaluate sources of error and standardization before power Doppler ultrasound becomes a routine measure of 'disease activity' in rheumatoid arthritis. Copyright (2005) Blackwell Science Pty Ltd

165

Color Doppler studies in trophoblastic tumors: a preliminary report.  

Science.gov (United States)

Ten women, referred because of a strong suspicion of gestational trophoblastic neoplasia, were examined by abdominal real-time ultrasound and color Doppler. The results were compared to those of pelvic angiography. In all but one case color Doppler examination revealed areas of increased vascularity. In all cases the findings of color Doppler and pelvic angiography agreed. Real-time ultrasound failed to detect abnormal uterine echoes in three of the patients where the other methods indicated tumor. The present study indicates that color Doppler could be of great value in a non-invasive assessment of trophoblastic tumors. PMID:12797041

Flam, F; Lindholm, H; Bui, T H; Lundström-Lindstedt, V

1991-09-01

166

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

Directory of Open Access Journals (Sweden)

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

Zanier Francesca

2007-01-01

167

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

168

Transcranial Doppler ultrasonography in intensive care.  

Science.gov (United States)

Transcranial Doppler is an innovative, flexible, accessible tool for the bedside monitoring of static and dynamic cerebral flow and treatment response. Introduced by Rune Aaslid in 1982, it has become indispensable in clinical practice. The main obstacle to ultrasound penetration of the skull is bone. Low frequencies, 1-2 MHz, reduce the attenuation of the ultrasound wave caused by bone. Transcranial Doppler also provides the advantage of acoustic windows representing specific points of the skull where the bone is thin enough to allow ultrasounds to penetrate. There are four acoustic windows: transtemporal, transorbital, suboccipital and retromandibular. The identification of each intracranial vessel is based on the following elements: (a) velocity and direction; (b) depth of signal capture; (c) possibility of following the vessel its whole length; (d) spatial relationship with other vessels; and (e) response to homolateral and contralateral carotid compression. The main fields of clinical application of transcranial Doppler are assessment of vasospasm, detection of stenosis of the intracranial arteries, evaluation of cerebrovascular autoregulation, non-invasive estimation of intracranial pressure, measure of effective downstream pressure and assessment of brain death. Mean flow velocity is directly proportional to flow and inversely proportional to the section of the vessel. Any circumstance that leads to a variation of one of these factors can thus affect mean velocity. The main pathological condition affecting flow velocity is the vasospasm. Vasospasm is a frequent complication of subarachnoid haemorrhage, it often remains clinically silent and the factors that make it symptomatic are largely unknown. Threshold velocities above which vasospasm comes into place are well defined as regards the median cerebral artery, while there is no consensus for the other vessels. Nevertheless, an increase in velocity alone is not sufficient to arrive at a diagnosis of vasospasm; a condition of hyperaemia also presents with an increase in flow velocity. The Lindegaard Index has therefore been introduced, which is defined by the ratio between the mean flow velocity in the median cerebral artery and the mean flow velocity in the internal carotid artery. Criteria for diagnosis of a stenosis >50% of an intracranial vessel with transcranial Doppler include: (a) segmentary acceleration of flow velocity; (b) drop in velocity below the stenotic segment; (c) asymmetry; and (d) circumscribed flow disturbances (turbulence and musical murmur). The transcranial Doppler enables us to assess both components of self-regulation. The static component is measured by observing changes in flow velocity caused by pharmacologically induced episodes of hypertension and hypotension. The dynamic component of autoregulation can be measured using a method devised by Aaslid known as the 'cuff test'. A very effective and safe device for measuring cerebral autoregulation is the transient hyperaemic response test. This test is based on the compensatory vasodilatation of the arterioles, which occurs after brief compression of the common carotid. Csonyka proposed the following formula based on clinical observation for the calculation of cerebral perfusion pressure: CPP = MAP x FVd/FVm + 14. Brain death is defined as the irreversible cessation of all functions of the whole brain. The clinical criteria are usually considered sufficient to establish a diagnosis of brain death; however, they might not be sufficient in patients who have been on sedatives or when there are ethical or legal controversies. Many authors have demonstrated the existence of a transcranial Doppler pattern, which is typical of brain death. PMID:18289437

Rasulo, F A; De Peri, E; Lavinio, A

2008-01-01

169

Evaluation of CIRS String Doppler Phantom as a Test Tool for Use in a Doppler Ultrasound Quality Assurance Program  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ultrasound Doppler systems are routinely used to perform blood flow velocity measurements which assist in the clinical assessment and diagnosis of vascular. Doppler measurements of peak velocities for vascular applications provide an indication of the degree of the stenosis which will ultimately assist in deciding how a patient is managed. It is imperative that Doppler systems are capable of accurately measuring blood flow velocities to ensure correct diagnosis and appropriate patient treatme...

Browne, Jacinta E.; Cournane, S.; Fagan, Andrew

2012-01-01

170

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

171

Catadioptric optics for laser Doppler velocimeter applications  

Science.gov (United States)

This paper examines the adaptation of low-cost Schmidt-Cassegrain astronomical telescopes to perform the laser-beam-focusing and scattered-light collection tasks associated with dual-beam laser Doppler velocimetry. A generic telescope design is analyzed using ray-tracing methods and Gaussian beam-propagation theory. A straightforward modification procedure to convert from infinite to near unity conjugate-ratio operation with very low residual aberration is identified and tested with a 200-mm-aperture telescope modified for f/10 operation. Performance data for this modified telescope configuration are near the diffraction limit and agree well with predictions.

Dunagan, Stephen E.

1989-01-01

172

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

173

Accuracy and precision in photonic Doppler velocimetry  

International Nuclear Information System (INIS)

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

174

Accuracy and precision in photonic Doppler velocimetry  

Science.gov (United States)

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

Dolan, D. H.

2010-05-01

175

Accuracy and precision in photonic Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

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

Dolan, D. H. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1195 (United States)

2010-05-15

176

Everyday relativity and the Doppler effect  

Science.gov (United States)

It is generally believed that special relativistic effects are important only when studying objects moving at speeds close to that of light. This belief leaves many practicing scientists and engineers with the impression that an understanding of relativity is not necessary for their day jobs. Our aim is to show that the ideas and mathematics of the special theory of relativity are used in practical applications involving objects moving much slower than the speed of light. In particular, we show how the Doppler shift for sound and light can be calculated from the postulates of relativity.

Picton Drake, Samuel; Purvis, Alan

2014-01-01

177

Laser Doppler velocimeter measurements in tornadolike vortices  

Science.gov (United States)

Using data recently gathered within the Purdue University tornado vortex chamber II (PU TVC II) using a state-of-the-art laser Doppler velocimeter (LDV), we present and discuss radial and vertical profiles of measured radial and tangential velocity components and derived vertical velocity component. A mean offset of the vortex from the centerline of the tornado vortex chamber (TVC) required a coordinate transformation of the measured data from a "chamber" reference frame to a "vortex" reference frame. Further, the impact of small vortex translations (vortex wander) on the data set is examined through the use of a simple mathematical model of the data collection process.

Lund, Donald E.; Snow, John T.

178

In-suit Doppler technology assessment  

Science.gov (United States)

The objective of this program was to perform a technology assessment survey of non-invasive air embolism detection utilizing Doppler ultrasound methodologies. The primary application of this technology will be a continuous monitor for astronauts while performing extravehicular activities (EVA's). The technology assessment was to include: (1) development of a full understanding of all relevant background research; and (2) a survey of the medical ultrasound marketplace for expertise, information, and technical capability relevant to this development. Upon completion of the assessment, LSR was to provide an overview of technological approaches and R&D/manufacturing organizations.

Schulze, Arthur E.; Greene, Ernest R.; Nadeau, John J.

1991-01-01

179

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

180

Doppler Tomographic Observations of Kepler-13b  

Science.gov (United States)

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

Johnson, Marshall C.; Cochran, William D.

2014-01-01

 
 
 
 
181

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

182

Doppler global velocimetry data in circular jets  

Science.gov (United States)

A two-component Doppler global velocimeter (DGV) system has been improved through the use of vapour-limited iodine cells that have temperature-independent responses, along with nonpolarizing beam splitters and lower f-number lenses. Two-component DGV velocity measurements have been obtained for a 1 inch diameter uniform circular jet flow at a nominal exit velocity of 60 m s-1, as well as for an annular jet and a swirling jet. These data generally agree with earlier point Doppler velocimeter and hot wire anemometer results to within about 2-4 m s-1, and display a total variability from a smooth curve of ±2-3 m s-1. This level of accuracy has been obtained for a system that uses a cw argon ion laser and eight-bit CCD cameras and digitizers. Exceptions to this level of accuracy are noted in regions of significant secondary scattering, due to scattered laser light that is reflected off the lip of the jet nozzle, as well as in regions of low smoke seeding levels, resulting in low signal-to-noise ratios. A significant amount of the variability of the data from a smooth curve is due to the flat field correction.

Kuhlman, John; Burton, Lucinda; Scarberry, Tom

2002-07-01

183

Comparison of Triature Doppler Velocimetry and Visar  

Energy Technology Data Exchange (ETDEWEB)

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 120{sup 0} 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 ({approx}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 {approx}200 ps. This resolution was better than that of a fast VISAR, which can achieve {approx}500 ps temporal resolution. Test methods and results are presented.

Gallegos, Cenobio H; Teel, Matthew; Romero, Vincent T; Diaz, Abel; Berninger, Michael [National Security Technologies, LLC, Los Alamos Operations 182 East Gate Drive, Los Alamos, NM 87544 (United States); Marshall, Bruce, E-mail: gallegch@nv.doe.go [National Security Technologies, LLC, Special Technologies Laboratory 5520-B Ekwill Street, Santa Barbara, CA 93111 (United States)

2010-08-01

184

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.

185

Comparison of Triature Doppler Velocimetry and Visar  

Science.gov (United States)

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 120° 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.

Gallegos, Cenobio H.; Marshall, Bruce; Teel, Matthew; Romero, Vincent T.; Diaz, Abel; Berninger, Michael

2010-08-01

186

Fiber Scrambling for Extreme Doppler Precision  

Science.gov (United States)

The detection of Earth-like exoplanets with the radial velocity method requires extreme Doppler precision and long-term stability in order to measure tiny reflex velocities in the host star. Recent planet searches have led to the detection of so called “super-Earths” (up to a few Earth masses) that induce radial velocity changes of about 1 m/s. However, the detection of true Earth analogs requires a precision of 10 cm/s. One of the factors limiting Doppler precision is variation in the Point Spread Function (PSF) from observation to observation due to changes in the illumination of the slit and spectrograph optics. Thus, this stability has become a focus of current instrumentation work. Fiber optics have been used since the 1980’s to couple telescopes to high-precision spectrographs, initially for simpler mechanical design and control. However, fiber optics are also naturally efficient scramblers. Scrambling refers to a fiber’s ability to produce an output beam independent of input. Our research is focused on understanding the scrambling properties of fibers with different geometries (circular, square, octagonal), different lengths and fiber sizes. Another important parameter when it comes to fibers is the so-called focal ratio degradation (FRD), which accounts for a different (faster) focal ratio after the fiber than the one sent into the fiber. In this paper, we will present new insight on fiber scrambling, FRD and what we call fiber personality, which describes differing behaviors for supposedly identical fiber.

Spronck, Julien; Kaplan, Z.; Fischer, D.

2011-09-01

187

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

188

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

DEFF Research Database (Denmark)

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

Christensen, Anders N; Reichkendler, Michala H

2014-01-01

189

?rinciple of relativity in navigation for example doppler meter speed  

Directory of Open Access Journals (Sweden)

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

?.?. ??????????

2006-01-01

190

Imaging doppler velocimeter with downward heterodyning in the optical domain  

Science.gov (United States)

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

Reu, Phillip L; Hansche, Bruce D

2013-05-21

191

Laser Doppler velocimetry and its application to turbulent flow measurements  

International Nuclear Information System (INIS)

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

192

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.)

193

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

194

Micro-Doppler classification of riders and riderless horses  

Science.gov (United States)

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

Tahmoush, David

2014-05-01

195

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

196

Ionospheric Doppler measurements by means of HF-radar techniques  

Directory of Open Access Journals (Sweden)

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

D. Altadill

2005-06-01

197

Teis? ? juridinio asmens pavadinim? ir jos gynimas  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Šiame darbe nagrin?jamas juridinio asmens pavadinimo apsaugos reglamentavimas bei teism? praktika Lietuvoje, Vokietijoje bei bendrai Europos S?jungos lygmeniu. Darbe pateikiama juridinio asmens pavadinimo samprata bei pavadinimo santykis su preki? ženklais ir domen? vardais. Didžiausias d?mesys skiriamas juridinio asmens pavadinimo gynimo b?d? bei s?lyg? analizei, pateikiami j? skirtumai ir ypatyb?s esant konfliktams tarp dviej? juridini? asmen? pavadinim?, tarp juridinio a...

S?imonyte?, Renata

2011-01-01

198

Doppler shift experiments with source in periodic motion: Parametrized Doppler shift formulas  

CERN Document Server

Doppler shift formulas are derived for two less studied scenarios: stationary receiver and source in harmonic oscillatory motion and stationary receiver and source in uniform circular motion. For each of the scenarios we derive a formula, one which works when the emission period is small enough that it can be considered that two successive signals are emitted from the same point in space (locality assumption) and another which takes into account that two successive signals are emitted from two different points in space (non-locality assumption). The results furnished by the two Doppler shift formulas are compared, showing that increasing the emission frequency decreases the difference between the results obtained with the two formulas.

Rothenstein, B; Rothenstein, Bernhard; Rothenstein, Albert

2003-01-01

199

Doppler global velocimetry - The next generation?  

Science.gov (United States)

A new measurement technique is being developed by NASA to measure off-surface flow fields. This method, Doppler global velocimetry, will allow quantification of complex three-dimensional flow fields at video camera rates. The entire flow field structure within a selected plane is measured simultaneously rather than by scanned, point-by-point measurements using conventional laser velocimetry. To assess the capability of this new technique, velocity measurements of the vortical flow field above a thin 75-degree delta wing were made in the NASA Langley Basic Aerodynamics Research Tunnel. The operation of the system is described along with the techniques developed to process the output images. The results are then compared with similar measurements obtained using a three component laser velocimeter.

Meyers, James F.

1992-01-01

200

Doppler Global Velocimetry: The Next Generation?  

Science.gov (United States)

A new measurement technique is being developed by NASA to measure off-surface flow fields. This method, Doppler global velocimetry, will allow quantification of complex three-dimensional flow fields at video camera rates. The entire flow field structure within a selected plane is measured simultaneously rather than by scanned, point-by-point measurements using conventional laser velocimetry. To assess the capability of this new technique, velocity measurements of the vortical flow field above a thin 75-degree delta wing were made in the NASA Langley Basic Aerodynamics Research Tunnel. The operation of the system is described along with the techniques developed to process the output images. The results are then compared with similar measurements obtained using a three component laser velocimeter.

Meyers, James F.

1991-01-01

 
 
 
 
201

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

202

Parallax effects in laser Doppler spectroscopy  

International Nuclear Information System (INIS)

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

203

A miniature, battery operated laser Doppler anemometer  

Science.gov (United States)

A hand-held lithium battery-operated 30 mW laser diode backscatter LDA is described. The LDA is constructed in a tube of 30 mm diameter and 250 mm length. The tube also contains microoptical beam collimation, a miniature galilean telescope, a miniature beamsplitter and prism, spatial filtering, a solid state detector, an electronic amplifier, a bandpass filter, a discriminator, and either (1) telemetry to transmit Doppler signals to a remote signal processor, or (2) integral frequency analysis and LCD display of single-component velocity. All the components are mounted on microoptical benching. The velocity measurement range is as much as a few meters per second, and the system operates for a few hours before battery replacement is necessary. The development of this LDA into modular mechanical form for easier replication is described. How the principles of this concept are extended to laser TOF anemometry and particle sizing is also discussed.

Brown, R. G. W.; Burnett, J. G.; Hackney, N.

204

[Cerebral microembolism detected by transcranial Doppler ultrasonography].  

Science.gov (United States)

The clinical diagnosis of brain embolism has traditionally been based on evidence suggesting a potential embolic source. However, it is now possible to detect circulating cerebral microemboli by means of transcranial Doppler ultrasound. We explain the theory behind microembolus detection, and discuss initial clinical experience of this method. During invasive cardiovascular investigations and surgery this method can warn the physician that microemboli are entering the cerebral circulation, and preventive measures can be taken. Cerebral microemboli are quite often detected in stroke prone patients, and their presence probably indicates increased risk of stroke. In the acute phase of ischemic stroke, microembolus detection may help to decide the etiology and the source of the emboli. When microemboli are detected in cases of acute embolic stroke, serial detections can be performed which, in future studies, might be of help when evaluating the effect of the treatment. PMID:9599505

Lund, C; Braekken, S K; Haggag, K J; Røste, L S; Russell, D

1998-03-30

205

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

Directory of Open Access Journals (Sweden)

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

Cibele Figueira Carvalho

2008-06-01

206

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

207

Is tissue Doppler echocardiography the Holy Grail for the intensivist?  

Science.gov (United States)

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 lateral and septal placed sample volume, there remain still several unanswered questions, particularly with respect to the preload dependency of these indices. PMID:17567926

Poelaert, Jan; Roosens, Carl

2007-01-01

208

Doppler global velocimeter development for large wind tunnels  

Science.gov (United States)

An optical, laser-based flow-field measurement technique for large wind tunnels is described. The technique, Doppler global velocimetry (DGV), uses laser sheet illumination and digital imaging to rapidly measure velocity distributions over large planar regions of the flow. DGV measures the Doppler shift of laser light scattered by aerosol particles that are added to the flow. An optical filter cell containing iodine vapour functions as a sensitive frequency discriminator that converts Doppler frequency to image intensity. The procedure used to process image intensity to yield three-component velocity maps is described. Measurement uncertainty is analysed and discussed, and sample measurements are presented.

Reinath, Michael S.

2001-04-01

209

A Modified Modulation Recognition Method against Doppler Effects  

Directory of Open Access Journals (Sweden)

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

Yaqin Zhao

2011-01-01

210

Role of Doppler ultrasound in the diagnosis of cerebrovascular insufficiency  

International Nuclear Information System (INIS)

Full text: By Doppler method, most insufficiency of function in the carotid, common carotid and vertebral arteries are diagnosed. 84.8% of people with insufficiency of common carotid on one or 2 sides have hypertension. By Doppler method, we have the possibility of diagnosing pathological net artery and vein blood flow in the brain, spasm of brain vessel and collateral blood supply resulting from obstruction of the carotid vessels. Comparative results of Doppler ultrasound and carotid angiography in the differential diagnosis of cerebral insufficiency will be discussed. (author)

211

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

212

The Next Generation Airborne Polarimetric Doppler Radar  

Science.gov (United States)

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

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

2013-04-01

213

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

International Nuclear Information System (INIS)

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

214

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-07-01

215

Differentiation of midbrain cystic lesions by duplex Doppler US  

International Nuclear Information System (INIS)

The addition of Doppler technology to an ultrasound imaging system allows easy differentiation of vascular from nonvascular masses. In addition, the characteristic flow in different arteries, veins, and arteriovenous communications allows accurate diagnosis of vascular structures. Cystic lesions in the region of the midbrain are uncommon but not rare in neonates, and it is important to differentiate between quadrigeminal plate cysts and vein of Galen aneurysms. Six neonates with cystic midbrain structures lying above the tectum were studied over a 2-year period. All were examined with duplex Doppler imaging and followed up by CT and angiography, when indicated. In two of the six infants a highly vascular signal was demonstrated with high flow rates and low impedance. Subsequent CT and angiography revealed typical vein of Galen aneurysms. The remaining four infants had cystic lesions that were avascular on Doppler imaging and demonstrated no enhancement on CT. Duplex Doppler imaging is helpful in the initial investigation of patients with midbrain cystic lesions

216

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

217

Doppler electron velocimetry : notes on creating a practical tool.  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-11-01

218

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

219

Doppler-free spectroscopy in driven three-level systems  

CERN Document Server

We demonstrate two techniques for studying the features of three-level systems driven by two lasers (called control and probe), when the transitions are Doppler broadened as in room-temperature vapor. For $\\Lambda$-type systems, the probe laser is split to produce a counter-propagating pump beam that saturates the transition for the zero-velocity atoms. Probe transmission then shows Doppler-free peaks, which can even have sub-natural linewidth. For V-type systems, the transmission of the control beam is detected as the probe laser is scanned. The signal shows Doppler-free peaks when the probe laser is resonant with transitions for the zero-velocity group. Both techniques greatly simplify the study of three-level systems since theoretical predictions can be directly compared without complications from Doppler broadening and the presence of multiple hyperfine levels in the spectrum.

Rapol, U D; Rapol, Umakant D.; Natarajan, Vasant

2004-01-01

220

Doppler Compensation by using of Segmented Match Filter  

Directory of Open Access Journals (Sweden)

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

Nader Ghadimi

2008-09-01

 
 
 
 
221

DELAY-DOPPLER PERFORMANCE OF HYPERBOLIC FREQUENCY MODULATION WAVEFORMS  

Directory of Open Access Journals (Sweden)

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

A.NAGAJYOTHI

2013-11-01

222

Ultraviolet-excimer laser-based incoherent Doppler lidar system  

Science.gov (United States)

The topics covered include the following: principles of Doppler measurements, laser backscatter, eye safety, demonstration concepts, the wavelength-meter, the interferometer detector, return signal model, and comparison of incoherent and coherent lidars.

Mcdermid, I. Stuart; Laudenslager, James B.; Rees, David

1985-01-01

223

A Digital Multigate Doppler Method for High Frequency Ultrasound  

Directory of Open Access Journals (Sweden)

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

Weibao Qiu

2014-07-01

224

Estimating delay and Doppler from a super resolution delay function  

Science.gov (United States)

Presented is a super resolution method for estimating the relative time delay of transmitted and received signals. The method is applied to the problem of accurately estimating both delay and Doppler effects from transmitted and received signals where the transmitter and receiver are moving with respect to each other. Unlike conventional methods based on the cross-ambiguity function (CAF), we use only the crosscorrelation function and estimate only delay with enough accuracy that accurate scale estimates may be obtained from the delay function. While CAF processes are two dimensional and are based on a linear approximation of the Doppler process, the method presented here represents a one dimensional solution based on the exact model of the Doppler process. While we address the problem in the context of resolving both delay and Doppler, the method may be used to obtain super resolution estimates of correlation delay in the case that delay is constant.

Nelson, D. J.

2008-08-01

225

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

Scientific Electronic Library Online (English)

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

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

2014-02-01

226

Cerebral blood flow with [15O]water PET studies using 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 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. Grey and white matter CBF values were 61.4 ± 11.0 and 15.6 ± 3.0 mL/min/100g 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/100g 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. PMID:23442733

Fung, Edward K; Carson, Richard E

2013-01-01

227

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

International Nuclear Information System (INIS)

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

228

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

Science.gov (United States)

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

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

2014-01-01

229

Color Doppler Ultrasonography in Evaluation of the Postoperative Penis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 penil...

Ghafouri, M.

2005-01-01

230

Digital Doppler extraction demonstration with the advanced receiver  

Science.gov (United States)

A digital Doppler extraction demonstration with the Advanced Receiver 2 (ARX 2) tracking Pioneer 10 and Voyager 2 is described. The measured results are compared with those of the Block 4 receiver that was operating in parallel with the ARX 2. It is shown that the ARX 2 outperforms the Block 4 receiver in terms of Allan variance of the Doppler residuals, the amount of which depends on the scenario of interest.

Hinedi, S.; Bevan, R.; Delcastillo, H.; Kinman, P.; Chong, D.; Labelle, R.

1990-01-01

231

Transthoracic Doppler echocardiography of the left internal mammary artery graft.  

Science.gov (United States)

Assessment of the left internal mammary artery (LIMA) graft patency currently requires invasive investigation through coronary angiography. In the last years the successful application of noninvasive Doppler spectrum analysis has been reported for patency assessment of the LIMA graft after myocardial revascularization. Echocardiography is considered to be a sensitive noninvasive screening modality to diagnose critical narrowing of LIMA grafts and angiography should be reserved for cases in which Doppler echocardiography fails to visualize the LIMA or reveals an abnormal flow pattern. PMID:23486624

Pârv, Andreea; Ober, Camelia; Bindea, Dan; Duncea, Caius

2013-03-01

232

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

233

Transcranial Doppler ultrasound and cerebral angiography - alternative or complementary  

International Nuclear Information System (INIS)

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

234

Two-way coherent Doppler error due to solar corona  

Science.gov (United States)

Two-way coherent Doppler errors resulting from phase scintillations induced on the uplink by the solar corona are considered. It is shown that this error can be estimated by taking statistics on the differential Doppler measurements. Typical estimates for the error are given for four Sun-Earth-probe angles and for integration times ranging from 1 second to 1 minute. These results are based on data collected during the 1985 Voyager 2 conjunction.

Kinman, P. W.; Asmar, S. W.

1988-01-01

235

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)

236

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

237

SIAMOIS: a Doppler asteroseismometer for Dome C  

Science.gov (United States)

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

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

238

High-momentum analysis in Doppler spectroscopy  

International Nuclear Information System (INIS)

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

239

Performance of an incoherent Doppler lidar system  

Science.gov (United States)

The performance of a space-borne incoherent Doppler lidar system has been discussed by using modeled atmosphere and analytical calculations. With using the modeled atmosphere, the analytical calculations, and reasonable instrumental parameters, we estimated the error on the line-of-sight (LOS) wind under the assumptions that the horizontal and temporal variation of tropospheric aerosol and atmospheric molecule is negligible in no cloud condition. We used the solar radiance value measured in the troposphere to discuss the LOS wind error on the effect of the solar radiance during daytime. Although the LOS wind error depends on the system parameters, the comparison between the various analytical calculations suggested that the LOS wind errors for those the analytical methods were almost the same values. The simulations showed that the LOS wind error during daytime was almost the same as that during nighttime, suggesting that the wind velocity can be made measurement under the same LOS wind error condition if the integrated solar bandwidth of the filter is narrow enough.

Ishii, Shoken; Mizutani, Kohei; Itabe, Toshikasu; Asai, Kazuhiro

2002-01-01

240

Doppler spectroscopy and collective flows in RFXmod  

Science.gov (United States)

Doppler spectroscopy based toroidal and poloidal flow velocities measured on the modified RFX Reversed Field Pinch are compared with the results obtained in the previous machine [1]. Passive measurements with integrated lines of sight confirm the decaying dependence of the toroidal plasma velocity with electron density but show a higher dynamics with respect to the past, often featuring significant accelerations during the plasma discharge. Edge flow, opposite to the core co-current flow, in presence of induced bulges of localized MHD modes or externally induced radial magnetic perturbations reverses its direction: this corresponds to a reversal of the radial electric field. A new diagnostic neutral beam injector (50 kV, 2.5 A equivalent current) has been recently installed for spatially resolved measurements. Preliminary results are presented. Among the main objectives of the system is a detailed measurement of the radius at which the radial electric field reverses and whether such radius coincides with the magnetic field reversal. [1] L. Carraro et al. Plasma Phys. Control. Fusion 40 (1998) 1021-1034.

Zaniol, B.

2005-10-01

 
 
 
 
241

Muscle activity characterization by laser Doppler Myography  

Science.gov (United States)

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

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

2013-09-01

242

Evaluating microcirculation by pulsatile laser Doppler signal  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2006-02-21

243

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

244

New developments in photon Doppler velocimetry  

Science.gov (United States)

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

Moro, E. A.

2014-05-01

245

Color Doppler imaging of cervicocephalic fibromuscular dysplasia  

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Full Text Available Abstract Background Fibromuscular dysplasia (FMD is a possible cause of stroke, especially in middle-aged women. However, only few reports are available on ultrasonographic detection and monitoring. Methods Among the 15,000 patients who underwent color Doppler imaging (CDI of the cervicocephalic arteries during the study period, all cases fulfilling ultrasound criteria of FMD were included into the case series. Criteria of FMD were: 1. Segmental string-of-beads pattern, 2. Localization in the distal extracranial part of internal carotid artery (ICA or vertebral artery (VA, and 3. (optional: Direct and/or indirect criteria of stenosis. Results CDI detected FMD in 39 vessels (37 ICA and 2 VA segments of 21 patients. 16 patients had bilateral manifestation on ICA, one of those also on VA, bilaterally. CDI disclosed 4 symptomatic high-grade ICA stenoses, 3 of them underwent endovascular treatment. 5 patients with moderate symptomatic ICA stenoses got medical treatment. In 6 patients FMD was the most likely cause of headache and in one patient FMD was diagnosed as a cause of vertigo. Conclusions CDI may be used for detection of cervicocephalic FMD. Due to the unfavourable localisation of FMD for CDI, the sensitivity of CDI is lower in comparison to angiography. However, high-grade FMD stenoses that require invasive treatment can be recognized on the basis of indirect hemodynamic criteria.

Grzyska Ulrich

2004-07-01

246

VW Hyi: optical spectroscopy and Doppler tomography  

CERN Document Server

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

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

2006-01-01

247

Colour Doppler flow imaging in regurgitant valvular heart disease.  

Science.gov (United States)

This brief discussion of colour Doppler flow imaging in regurgitant valvular lesions has focused on the emerging information about the sensitivity and specificity of this technique. This technique has been of unquestionable value to the echocardiographer in delineating regurgitant lesion. However, the clinician should be aware of the large number of factors that affect the colour Doppler flow image of the regurgitant jet, such as jet size, Doppler instrumentation and Doppler physics such as attenuation, angle, dependency, gain dependency as well as such artefacts or ghosting and reverberation. Characteristics of colour Doppler flow image of the regurgitant jet provide data that must still be considered semiquantitative because, in addition to the amount of the regurgitant volume, other factors affect the image such as the size and compliance of the receiving changer, the size of valve defect and differential pressure and velocity of regurgitant jet. Interpretation of the literature on sensitivity and specificity of this technique requires an understanding of these factors and awareness of the relatively few studies that have examined this question. Colour Doppler flow imaging has the potential, and should continue, to improve the noninvasive assessment of regurgitant valvular lesions. PMID:3228757

Skwarok, D; Rabkin, S W

1988-10-01

248

Doppler Findings in Intrapartum Fetal Distress  

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

Khatereh Tooba

2011-08-01

249

Doppler ultrasound and giant cell arteritis  

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Full Text Available Ana Marina Suelves1, Enrique España-Gregori1,2, Jose Tembl3, Stephanie Rohrweck1, Jose Maria Millán4, Manuel Díaz-Llopis1,4,51Service of Ophthalmology, La Fe University Hospital, Valencia, Spain; 2Department of Optics, University of Valencia, Valencia, Spain; 3Service of Neurology, La Fe University Hospital, Valencia, Spain; 4CIBERER, Ciber de Enfermedades Raras, Valencia, Spain; 5Faculty of Medicine, University of Valencia, Valencia, SpainObjective: To evaluate the utility of ultrasound in aiding the diagnosis of giant cell arteritis (GCA, in monitoring the response to corticotherapy, and in detecting early relapses.Methods: A pilot study, prospective, included 10 patients with suspected GCA. All patients underwent ultrasound examination of both temporal arteries before temporal artery biopsy (TAB, 3 weeks after starting treatment, and 3 months after diagnosis. For this study, the histological findings alone were used to define if patients were suffering from GCA. The findings on ultrasound were compared with the results of biopsy. The best place to perform TAB was observed by ultrasound.Results: All patients with positive biopsy were detected with ultrasound. No false positives were observed on ultrasound. The results presented give a sensibility, specificity, and positive predictive value of 100% for the use of ultrasound in the diagnosis of GCA. Two relapses were detected early by ultrasound during the follow-up.Conclusions: This pilot study suggests that eco-doppler may be a useful tool in diagnosis and clinic follow-up in patients with suspected GCA.Keywords: giant cell arteritis, ultrasound, temporal artery biopsy, optic nerve

Ana Marina Suelves

2010-11-01

250

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

251

ADEPT - Abnormal Doppler Enteral Prescription Trial  

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

McCormick Kenny

2009-10-01

252

[Transcranial color Doppler guided Matas' test].  

Science.gov (United States)

Carotid artery involvement in head and neck tumor is a great concern to surgeons because of the unpredictable effects of its resection. For the investigation of brain collateral circulation, color Doppler guided Matas' test has been performed to examine blood flow in the middle cerebral artery (MCA) and internal carotid artery (ICA). SSA-270A convex (3.75MHz) and linear (3.75MHz, 2.5MHz) array probes (Toshiba Co., Ltd.) were used for this investigation. A temporary occlusion test (60 sec) was performed on the common carotid artery (CCA) in thirty patients who were scheduled to undergo radical neck dissection. The blood flow velocity of MCA during Matas' test was recorded. Then relative flow (percent blood flow before the test) of MCA during the 60 sec Matas' test was measured. The relative mean flow was 72% with a standard deviation of 15%. The results of thirty patients were classified into four groups according to the relative flow of MCA after 60 sec occlusion of the common carotid artery: Group A, over 87% (three cases); Group B, 86-72% (twelve cases); Group C, 71-57% (twelve cases); Group D, under 56% (three cases). Brain collateral circulation (BCC) of the Group A patients was considered to be excellent, and therefore reconstructive vascular surgery (RVS) was not necessarily indicated. In Group B patients (fair) and Group C patients (slightly poor) further investigation of BCC, i.e., Balloon Matas' test (occlusion of CCA and ICA), SPECT and brain angiography, was considered to be necessary. In Group D patients (poor) RVS was inevitable if either CCA or ICA had to be resected. Important information is provided by this noninvasive examination to predict the risk of carotid resection. This test seems to be useful to determine whether or not RVS is indicated. PMID:1744794

Takeuchi, Y

1991-09-01

253

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

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

Thomas George

2004-08-01

254

Doppler Signatures of the Atmospheric Circulation of Hot Jupiters  

Science.gov (United States)

To date, the exotic meteorology of hot Jupiters has primarily been characterized with thermal measurements, providing only indirect clues to the wind regime. Recently, however, Snellen et al. (2010) presented high-resolution groundbased transit spectra of HD209458b containing an apparent 2 km/sec blueshift, which they interpreted as a signature of atmospheric winds flowing from dayside to nightside toward Earth along the planet's terminator. Motivated by these observations, we describe the types of Doppler signatures generated by the atmospheric circulation and show how Doppler measurements can place powerful constraints on the meteorology. We show that, depending on parameters, the atmospheric circulation--and Doppler signature--of hot Jupiters splits into two regimes. At moderate stellar insolation, the day-night thermal forcing generates fast east-west jet streams from the interaction of standing planetary-scale 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 bimodal Doppler signature exhibiting distinct, superposed blue- and redshifted velocity peaks. Under more intense stellar insolation, however, the thermal forcing is so strong that it damps these planetary-scale waves, inhibiting their ability to generate jet streams. As a result, this second regime exhibits a circulation dominated primarily by high-altitude, day-to-night airflow along both terminators rather than longitudinally symmetric jets. This causes air to flow toward Earth along most of the terminator, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art 3D circulation models including nongrey radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that HD189733b lies in the first regime while HD209458b lies in the second regime. Moreover, we show how the amplitude of the Doppler shifts place strong constraints on the strength of frictional drag in the upper atmospheres of hot Jupiters.

Showman, Adam P.; Fortney, J. J.; Lewis, N. K.; Shabram, M.

2011-09-01

255

Comparison between oscillometric- and Doppler-ABI in elderly individuals  

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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

256

Differentiation of abdominal lymphadenoptahy with power doppler sonography  

International Nuclear Information System (INIS)

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

257

Renal Power Doppler Ultrasonographic Evaluation of Children With Acute Pyelonephritis  

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

Ali Pahlusi

2011-10-01

258

Color Doppler US in the acute scrotal disease  

Energy Technology Data Exchange (ETDEWEB)

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

Cha, Yoo Mi; Yang, Dal Mo; Kang, Sook Wook; Kim, Hyung Sik; Lee, Young Seok; Kim, Hyeon Hoe [Chung Ang Gil Hospital, Incheon (Korea, Republic of)

1993-12-15

259

Blood flow measurement by laser Doppler method in orofacial region  

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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

260

Doppler Uterine Artery Flow Velocimetry in Prediction of Preterm Labor  

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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

 
 
 
 
261

Acute intrascrotal pathology in childhood: color Doppler study  

International Nuclear Information System (INIS)

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

262

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

263

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

264

Flow measurement during compression using doppler global velocimetry; Stroemungsmessung waehrend der Kompression mit Doppler Global Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

IAV GmbH has been using Doppler Global Velocimetry (DGV) for a number of years on a routine basis for steady-state flow testing in its combustion process and port development activities. In order to visualize the influence of piston geometry and dynamic effects on in-cylinder flow, the DGV measurement technique has been taken forward as part of a cooperation agreement between DLR e.V. (German Aerospace Center) and IAV GmbH. As a result, measurements are conducted on the motored engine during the compression phase and displayed in the context of steady-state intake flow. The measurement technique can be adapted to production engines with little effort. (orig.)

Dingel, O.; Seidel, T.; Steuker, H. [Geschaeftsbereich Powertrain Entwicklung, IAV GmbH (Germany)

2006-05-15

265

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

Science.gov (United States)

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

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

1991-01-01

266

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

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

S Shahriaran

2002-09-01

267

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)

268

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)

269

Doppler spectroscopy, a powerful tool for studying molecular collision dynamics  

International Nuclear Information System (INIS)

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

270

Detection of electron velocity in graphene by Doppler effect  

Science.gov (United States)

Electron velocity in a two-dimensional electron gas can be measured by Doppler shift. Thus, we construct the Doppler shift of light and apply it to the motion of electrons in a graphene sheet to estimate the electron velocity. Here, a laser beam with initial frequency is incident on the graphene sheet in a parallel direction, and then the frequency of the emitted light can be measured by spectroscopy after detecting the electron velocity. Then, the ratio of frequency shift from the Doppler effect is described in terms of the electron velocity, as well as the incident and the detection angle of laser beam. The thermal broadening of detected frequency as a function of velocity is also shown for different temperatures.

Kim, Heetae; Park, Chang-Soo; Cho, Hak Dong

2014-11-01

271

Assessment of endometrial receptivity by Color Doppler and ultrasound imaging  

Directory of Open Access Journals (Sweden)

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

Lili? Vekoslav

2007-01-01

272

Diagnosis of subclavian steal syndrome using color doppler ultrasonography  

International Nuclear Information System (INIS)

Objective: To evaluate the diagnostic value of color Doppler ultrasonography in subclavian steal syndrome (SSS). Methods: The sonographic appearance and the hemodynamic data of extracranial vertebral, subclavian, innominate arteries in 30 patients with SSS were displayed with color Doppler ultrasonography, and do tourniquet test. Results: The insidious group included 6 cases (20.0%), the partial group included 14 cases (46.6%) and the completed group included 10 (33.3%). The accurately diagnosed cases by ultrasound were 28 (93.3%). The misdiagnosed cases were 2 (6.7%, all in the insidious group). Conclusion: Color Doppler ultrasonography can be prompted to subclavian steal the lesion site, extent and causes, while effectively evaluate the hemodynamic changes in the clinical diagnosis of SSS is the preferred method of imaging examination. (authors)

273

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

274

All-sky Doppler interferometer for thermospheric dynamics studies.  

Science.gov (United States)

An efficient, all-sky input optical system has been mated to a 100-mm-aperture Fabry-Perot interferometer that employs a cooled (-150 °C) CCD as a photon detector to create an all-sky Doppler interferometer. The instrument is capable of simultaneously measuring Doppler shifts and widths of nightglow emission lines from many different points in the sky, thereby providing determinations of upperatmosphere neutral wind and temperature fields over a large region (to ?2000 km in extent). For OI 630-nm (thermosphere) and OH 799.6-nm (mesopause) nightglow emissions, exposure times of 5-15 min provide good-quality interferometric images. The capability of the all-sky Doppler interferometer is illustrated by examples of thermospheric wind and temperature fields measured over Millstone Hill, Massachusetts. PMID:21037707

Biondi, M A; Sipler, D P; Zipf, M E; Baumgardner, J L

1995-04-01

275

Vein Thrombosis Associated with Umbilical Vascular Catheters with Color Doppler  

Directory of Open Access Journals (Sweden)

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

Masoud Nemati

2013-01-01

276

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

277

Effect of surface reflectivity on photonic Doppler velocimetry measurement  

Science.gov (United States)

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

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

2014-05-01

278

Imaging nanoparticle flow using magneto-motive optical Doppler tomography  

Energy Technology Data Exchange (ETDEWEB)

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 (B{sub max} = 1 T, {nabla}B{sup 2}=220T{sup 2}m{sup -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.

Kim, Jeehyun [Beckman Laser Institute and Medical Clinic, University of California, 1002 Health Sciences Road East, Irvine, CA 92612 (United States); Oh, Junghwan [Biomedical Engineering Department, University of Texas, Austin, TX 78712 (United States); Milner, Thomas E [Biomedical Engineering Department, University of Texas, Austin, TX 78712 (United States); Nelson, J Stuart [Beckman Laser Institute and Medical Clinic, University of California, 1002 Health Sciences Road East, Irvine, CA 92612 (United States)

2007-01-24

279

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

280

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

 
 
 
 
281

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

Science.gov (United States)

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

2010-01-01

282

The Dependence of the Resonance Integral on the Doppler Effect  

International Nuclear Information System (INIS)

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

283

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

284

Miniature Laser Doppler Velocimeter for Measuring Wall Shear  

Science.gov (United States)

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

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

2005-01-01

285

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.)

286

The Doppler-defect benchmark: Overview and summary of results  

International Nuclear Information System (INIS)

A set of computational benchmarks for the Doppler reactivity defect has been specified for fuel pin cells containing normal or enriched UO2 fuel, reactor-recycle mixed-oxide (MOX) fuel, or weapons-grade MOX fuel. This Doppler benchmark has been approved by the Joint Benchmark Committee of the Mathematics and Computations, Reactor Physics, and Radiation Protection and Shielding Divisions of the American Nuclear Society. This paper describes the benchmark specifications and provides a succinct summary of the results submitted for it. Some of those results are described in more detail in individual companion papers submitted by the participants. The complete set of benchmark specifications is provided in Appendix A. (authors)

287

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.

288

Prenatal color Doppler ultrasonographic diagnosis of fetal tetralogy of Fallot  

International Nuclear Information System (INIS)

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

289

Special theory of relativity through the Doppler effect  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-11-01

290

Transurethral resection syndrome detected and managed using transesophageal Doppler.  

Science.gov (United States)

Transurethral resection syndrome during transurethral resection of the prostate (TURP) results from excessive absorption of electrolyte-free irrigation fluids causing acute hypervolemia and hyponatremia. Neuraxial anesthesia is often recommended for TURP procedures because early signs of neurological deterioration can be detected. However, in patients requiring general anesthesia, other continuous and noninvasive measures are needed. Acute intravascular hypervolemia should be reflected by changes in hemodynamic values. Transesophageal Doppler ultrasonography of the aorta allows determination of stroke volume and other advanced hemodynamic variables related to intravascular volume status. We describe the first case of intraoperative detection of a TURP syndrome by noninvasive Doppler monitoring of hemodynamic variables during TURP. PMID:18713906

Schober, Patrick; Meuleman, Eric J H; Boer, Christa; Loer, Stephan A; Schwarte, Lothar A

2008-09-01

291

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

292

Micro-Doppler Frequency Estimation Based on Radon-Wigner Transform  

Directory of Open Access Journals (Sweden)

Full Text Available A nonparametric computationally efficient algorithm is proposed for micro-Doppler frequency estimation, assuming that this non-linear micro-Doppler frequency is approximate linear frequency in short-time intervals. In this algorithm, we use Radon-Wigner transform in short-time intervals to estimate micro-Doppler frequency. Simulation results confirm the effectiveness of the proposed method.

Sun Huixia

2014-01-01

293

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

294

Language Lateralization in Children Using Functional Transcranial Doppler Sonography  

Science.gov (United States)

Aim: Language lateralization with functional transcranial Doppler sonography (fTCD) and lexical word generation has been shown to have high concordance with the Wada test and functional magnetic resonance imaging in adults. We evaluated a nonlexical paradigm to determine language dominance in children. Method: In 23 right-handed children (12…

Haag, Anja; Moeller, Nicola; Knake, Susanne; Hermsen, Anke; Oertel, Wolfgang H.; Rosenow, Felix; Hamer, Hajo M.

2010-01-01

295

Methodology and reproducibility of bidirectional laser Doppler velocimetry  

International Nuclear Information System (INIS)

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

296

Check list Doppler and duplex sonography. 4. rev. ed.  

International Nuclear Information System (INIS)

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.

297

Color Doppler sonographic findings in focal spleen lesions  

Energy Technology Data Exchange (ETDEWEB)

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

Bachmann, Christian [Department of Internal Medicine, Philipps University Marburg, Baldingerstrasse, D-35043 Marburg (Germany); Goerg, Christian [Department of Internal Medicine, Philipps University Marburg, Baldingerstrasse, D-35043 Marburg (Germany)]. E-mail: christian.goerg@med.uni-marburg.de

2005-12-15

298

Enhanced color Doppler sonography of eye and orbit tumors  

International Nuclear Information System (INIS)

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

299

Development of Rayleigh Doppler lidar for measuring middle atmosphere winds  

Science.gov (United States)

Interpretation of most of the middle and upper atmospheric dynamical and chemical data relies on the climatological description of the wind field Rayleigh Doppler lidar is one instrument which monitors wind profiles continuously though continuity is limited to clear meteorological conditions in the middle atmosphere A Doppler wind lidar operating in incoherent mode gives excellent wind and temperature information at these altitudes with necessary spectral sensitivity It observes atmospheric winds by measuring the spectral shift of the scattered light due to the motions of atmospheric molecules with background winds and temperature by spectral broadening The presentation is about the design and development of Incoherent Doppler lidar to obtain wind information in the height regions of 30-65 km The paper analyses and describes various types of techniques that can be adopted viz Edge technique and Fringe Imaging technique The paper brings out the scientific objectives configuration simulations error sources and technical challenges involved in the development of Rayleigh Doppler lidar The presentation also gives a novel technique for calibrating the lidar

Raghunath, K.; Patra, A. K.; Narayana Rao, D.

300

Critical design parameters in laser Doppler perfusion imaging  

Science.gov (United States)

Laser Doppler Perfusion Imaging (LDPI) is a method for visualization of tissue blood perfusion. A low power laser beam is used to step-wise scan a tissue area of interest and a perfusion estimate based on the backscattered, partially Doppler broadened, light is generated. Although the basic operating principle of LDPI is the same as that of conventional Laser Doppler Perfusion Monitoring (LDPM), significant differences exist between the implementation of the methods which must be taken into account in order to generate high quality perfusion images. The purpose of this study is to investigate the relevance of a number of LDPI design parameters, such as: (1) The influence of artifact noise when using a continuously moving laser beam instead of a step-wise moving beam to scan the image. (2) The signal processor output's dependency on the distance between the measurement object and the scanner head when using collimated laser light. (3) The speed and mode of the scanning. The results show a substantial rise in the noise level when using a continuously moving beam as opposed to a step-wise. Skin measurements using a collimated laser beam demonstrated an amplification factor dependency on the distance between the skin surface and the scanner head not present when using a divergent laser beam. The scanning speed is limited by the trade-off between the Doppler signal lower cut-off frequency and the image quality.

Arildsson, Mikael L.; Nilsson, Gert E.; Wardell, Karin

1996-05-01

 
 
 
 
301

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

302

Predictive analog to digital conversion of Doppler ultrasound signals.  

Science.gov (United States)

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

Bøe, S; Kristoffersen, K

1995-03-01

303

Dual beam translator for use in Laser Doppler anemometry  

Science.gov (United States)

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

Brudnoy, David M. (Albany, NY)

1987-01-01

304

Pulsed laser-Doppler flowmetry for monitoring deep perfusion  

Science.gov (United States)

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

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

2001-10-01

305

The role of color flow Doppler ultrasound in dialysis access.  

Science.gov (United States)

Color flow Doppler provides accurate imaging and access flow volume measurement of the hemodialysis vascular access. It can readily identify subsets of patients at high risk for future thrombosis. It is noninvasive, mobile, and allows convenient clinical evaluation at the dialysis facility. In Europe, Doppler ultrasound has become the standard of care for evaluation of arteriovenous (AV) fistula dysfunction and is essential in the preoperative evaluation for access placement. It also can diagnose the arterial inflow disease that has become more prevalent in our aging, diabetic, end-stage renal disease (ESRD) population. Access management programs based on Doppler ultrasound have been highly successful and have produced outcome data as good or better than provided with other techniques. In light of its proven clinical efficacy, reimbursement and regulatory agencies should allow its appropriate inclusion into integrated access management programs. In conclusion, Doppler ultrasound should be included as a part of an integrated vascular access management program. This is supported by clinical outcome data and direct comparisons with other modalities. PMID:12012305

Sands, Jeffrey J; Ferrell, Lori M; Perry, Michael A

2002-05-01

306

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

307

Color Doppler sonographic findings in focal spleen lesions  

International Nuclear Information System (INIS)

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

308

Unidirectional Rotation of Molecules Measured by the Rotational Doppler Effect  

Directory of Open Access Journals (Sweden)

Full Text Available A pair of linearly polarized pump pulses induce field-free unidirectional molecular rotation, which is detected by a delayed circularly polarized probe. The polarization and spectrum of the probe are modified by the interaction with the molecules, in accordance with the Rotational Doppler Effect.

Prior Yehiam

2013-03-01

309

Estimation of amputation level with a laser Doppler flowmeter.  

DEFF Research Database (Denmark)

Leg amputation levels were decided in 24 patients suffering from atherosclerosis, using the conventional techniques of segmental blood pressure and radioisotope skin clearance. The skin microcirculation was measured and recorded before operation with a laser doppler flowmeter. A high correlation was found between the successful amputation levels and the maximal blood perfusion of the skin measured in this way.

Gebuhr, Peter Henrik; JØrgensen, J P

1989-01-01

310

Research on Fast-Doppler-Broadening of neutron cross sections  

International Nuclear Information System (INIS)

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

311

Diagnostic usefulness of findings in Doppler sonography for amelanotic melanoma.  

Science.gov (United States)

To evaluate the diagnostic usefulness of Doppler sonography for amelanotic melanoma (AM), the correspondence between the findings of dermoscopy and Doppler sonography was investigated in AM in comparison with other hypopigmented tumors. Seven cases with AM and 11 cases with squamous cell carcinoma (SCC), 10 cases with non- or hypopigmented basal cell carcinoma (NP-BCC) and six cases with eccrine poroma (EP) as hypopigmented tumors were investigated. EP is readily recognized by differences from AM and SCC based on a single vertical and non-torvtuous vessels. NP-BCC is distinguished from AM based on tortuosity running in a vertical direction. Though findings of tortuosity in vessels and heterogeneity of vessel size are recognized both in AM and SCC: (i) abundant blood flow was recognized more clearly in AM; (ii) total blood flow was more than 40% in most cases of AM (average, 60.9%); and (iii) more vessels which flow into a tumor are found in AM (85.7%). There is no relationship between dermoscopic findings of vessel types and Doppler sonography findings of vessels. In this study, the diagnostic usefulness of the above-mentioned specific findings in examination may suggest using Doppler sonography for AM as one non-invasive method. PMID:23802993

Kato, Masayuki; Mabuchi, Tomotaka; Yamaoka, Hanako; Ikoma, Norihiro; Tamiya, Shiho; Ozawa, Akira; Taguchi, Masahito; Kuramochi, Akira; Tsuchida, Tetsuya

2013-09-01

312

The Dark Side of the Universe: Doppler Shift  

Science.gov (United States)

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

313

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

314

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

315

Doppler signatures of the atmospheric circulation on hot Jupiters  

Science.gov (United States)

To date, the exotic meteorology of hot Jupiters has primarily been characterized with thermal measurements of secondary eclipse depths and phase curves, providing only indirect clues to the wind regime. Recently, however, Snellen et al. (2010) presented highresolution groundbased spectra of HD 209458b obtained during transit. From analysis of the data, they reported an overall 2±1 km/sec blueshift in 56 spectral lines of carbon monoxide, which they interpreted as a signature of atmospheric winds flowing from dayside to nightside toward Earth along the planet's terminator. Although the detection is tentative, these observations pave the way for an entirely new approach to characterizing hot Jupiter meteorology. Motivated by these observations, we describe the types of Doppler signatures generated by the atmospheric circulation and show how Doppler measurements can place powerful constraints on the meteorology. We show that, depending on parameters, the atmospheric circulation—and Doppler signature—of hot Jupiters split into two regimes. In one regime, at moderate stellar insolation, the day-night thermal forcing generates fast east-west jet streams from the interaction of standing planetary-scale waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows strongly toward Earth in some regions and away from Earth in others, leading to a bimodal Doppler signature exhibiting distinct, superposed blue- and redshifted velocity peaks. In the other regime, which occurs at intense stellar insolation, the thermal forcing is so strong that it damps these planetary-scale waves, inhibiting their ability to generate jet streams. As a result, this second regime exhibits a circulation dominated primarily by highaltitude, day-to-night airflow along both terminators rather than longitudinally symmetric jets. This implies that air flows toward Earth along most of the terminator, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art three-dimensional circulation models including nongrey radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that HD 189733b lies in the first regime while HD 209458b lies in the second regime. Moreover, we show how the amplitude of the Doppler shifts and the inferred velocities place strong constraints on the strength of frictional drag—due to Lorentz-force braking or other processes—in the upper atmospheres of hot Jupiters.

Showman, A. P.; Fortney, J. J.; Lewis, N. K.; Shabram, M.

2011-10-01

316

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

317

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.

318

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

319

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

320

Power Doppler imaging and color Doppler flow imaging for the evaluation of normal and pathological vertebral arteries.  

Science.gov (United States)

Recently, an ultrasound method for vascular applications using the amplitude of the reflected echosignal for the generation of intravascular color signals has been introduced. We compared the utility of this power Doppler imaging (PDI) with conventional color Doppler flow imaging (CDFI) for examination of vertebral arteries (VA). Forty-nine patients with signs and symptoms suggesting ischemia within the posterior circulation were evaluated. Quality of blood flow visualization by PDI and CDFI at the different VA segments was classified according to a four point scale. Furthermore, combined sonographic findings were correlated with the results of digital substraction and/or magnetic resonance angiography (DSA, MRA). Power Doppler imaging provided a significantly superior visualization of the intertransversal VA, whereas display of the intracranial V4 segment was superior significantly on CDFI. Both methods were complementary for the evaluation of the VA at the origin. With respect to the angiographic findings, combined CDFI and PDI achieved a sensitivity of 90.63% and a specificity of 97.22% for the differentiation of healthy and pathologic VAs. Power Doppler imaging is complementary to CDFI for the sonographic assessment of VA disease. Combined use of PDI and CDFI achieves a high sensitivity and specificity, thus increasing diagnostic confidence. PMID:9557142

Ries, S; Steinke, W; Devuyst, G; Artemis, N; Valikovics, A; Hennerici, M

1998-04-01

 
 
 
 
321

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

322

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

Scientific Electronic Library Online (English)

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

Pablo Andrés, Victoria-Gómez.

323

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

Scientific Electronic Library Online (English)

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

Cibele Figueira, Carvalho; Maria Cristina, Chammas; Giovanni Guido, Cerri.

324

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

325

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

326

Doppler broadening measurements in FRX-C/LSM  

International Nuclear Information System (INIS)

Measurements obtained in situ during field reversed configuration (FRC) formation show that the Doppler broadening ion temperature TCV is larger by a factor of two or more than the ion temperature Ti derived from pressure balance and Thomson scattering. After a time comparable to an ion-ion equilibrium time, TCV and Ti come into agreement with each other. An exception to this picture occurs in the lowest fill pressure condition (2 mtorr), for which TCV > Ti is maintained throughout the FRC lifetime. Earlier Doppler broadening measurements in FRX-B and FRX-C also showed persistent, anomalously high TCV at low fill pressure. The initially high values of TCV are probably caused by convective motion generated by the radial implosion. The low fill pressure results suggest an enhanced ohmic power input to the carbon ions. 7 refs., 3 figs

327

Normal Doppler velocimetry of renal vasculature in Persian cats.  

Science.gov (United States)

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

Carvalho, Cibele F; Chammas, Maria C

2011-06-01

328

Doppler lidar for measurement of atmospheric wind fields  

Science.gov (United States)

Measurements of wind fields in the earth's troposphere with daily global coverage is widely considered as a significant advance for forecasting and transport studies. For optimal use by NWP (Numerical Weather Prediction) models the horizontal and vertical resolutions should be approximately 100 km and 1 km, respectively. For boundary layer studies vertical resolution of a few hundred meters seems essential. Earth-orbiting Doppler lidar has a unique capability to measure global winds in the troposphere with the high vertical resolution required. The lidar approach depends on transmission of pulses with high spectral purity and backscattering from the atmospheric aerosol particles or layered clouds to provide a return signal. Recent field measurement campaigns using NASA research aircraft have resulted in collection of aerosol and cloud data which can be used to optimize the Doppler lidar instrument design and measurement strategy.

Menzies, Robert T.

1991-01-01

329

An ideal blood mimicking fluid for doppler ultrasound phantoms  

Directory of Open Access Journals (Sweden)

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

Samavat H

2006-01-01

330

US-Doppler in the evaluation of hemodialysis arteriovenous fistulas  

International Nuclear Information System (INIS)

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

331

Novel Doppler laser radar for diagnostics in fusion reactors  

International Nuclear Information System (INIS)

We describe the development of a novel Doppler laser radar (DOLAR) for remote measurement of flow velocity (0-10 m/s) and film thickness of liquid metal walls, currently being studied for their superior heat handling and self-healing characteristics. Small fluctuations in flow velocity(?mm/s) and flow thickness (?50 ?m) that may arise during plasma discharges can also be measured. The DOLAR is also designed for non intrusive mapping of features of plasma-facing solid surfaces with very high precision (?50 ?m). It can also measure the motion of structural components of a fusion reactor during plasma discharges and during plasma disruptions. The device utilizes frequency modulation laser radar principles for precision range measurements. Compensation of Doppler frequency shift is used to measure flow velocity. The DOLAR probe head is designed with acousto-optic and piezoelectric devices for operation in the harsh fusion environment

332

Remote intensity fluctuation measurements with a laser Doppler radar  

Science.gov (United States)

A coaxial focused CW scanning laser Doppler velocimeter (SLDV) radar equipment applying heterodyne detection at 10.6 microns can measure intensity fluctuations under field conditions. The set includes a 20 W CO2 laser, a coaxial Cassegrainian telescope, standard heterodyne equipment, and a SAW spectrum analyzer with 100 kHz signal resolution. Operation of the equipment and techniques for taking remote measurements are described briefly. Applications to remote measurements of transverse component of wind speed, as a complement to the traditional Doppler method of determining axial velocity, are under study. SLDV equipment has been used in detection, tracking, and measurements of atmospheric turbulence associated with aircraft wing-tip vortices or with dust devils, and in measurement of general atmospheric wind profiles.

Kennedy, L. Z.; Bilbro, J. W.

1976-01-01

333

Multi-slit spectrograph and H alpha Doppler system  

Science.gov (United States)

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

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

1974-01-01

334

HF Doppler observations of acoustic waves excited by the earthquake  

Science.gov (United States)

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

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

1985-01-01

335

A reliable Doppler-based solution for single sensor geolocation  

Science.gov (United States)

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

Witzgall, H.

336

Gravitational Doppler effect explored by means of a geostationary satellite  

International Nuclear Information System (INIS)

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

337

3D color Doppler of monoamniotic twin cord entanglement.  

Science.gov (United States)

Cord entanglement is a leading cause of mortality of monochorionic monoamniotic twins. Few studies focused on entanglement features/structure itself. Three-dimensional color Doppler ultrasound was conducted to evaluate the cord entanglement in monoamniotic twins at 30 weeks of gestation. Ultrasound revealed detailed features: the two cords were entangled at several points with a chain-like appearance and this complicated structure led us to closely monitor fetal well-being. Seven days later, non-reassuring fetal heart rate pattern was observed, and cesarean section was performed at 30 6/7 pregnancy week, yielding female infants without neurological sequelae. Three-dimensional color Doppler clearly delineated the features of entanglement, and thus was useful for evaluating cord entanglement in monoamniotic twins. PMID:19956962

Kuwata, Tomoyuki; Matsubara, Shigeki; Suzuki, Mitsuaki

2010-05-01

338

Development of Doppler Global Velocimetry for Wind Tunnel Testing  

Science.gov (United States)

The development of Doppler global velocimetry is described. Emphasis is placed on the modifications necessary to advance this nonintrusive laser based measurement technique from a laboratory prototype to a viable wind tunnel flow diagnostics tool. Several example wind tunnel flow field investigations are described to illustrate the versatility of the technique. Flow conditions ranged from incompressible to Mach 2.8 with measurement distances extending from 1 to 15 m.

Meyers, James F.

1994-01-01

339

Cardiac relaxation dynamics investigated by Doppler Tissue Imaging (DTI)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Following an initial pilot study to explore the usefulness of Doppler tissue imaging (DTI) for the assessment of regional systolic dysfunction in the ischaemic heart, new techniques for the diagnosis of diastolic dysfunction have been developed In the refinement of the techniques further evidence to support the existence of the early diastolic mechanism was obtained prior to assessing its clinical utility. For this the relationship between peak early diastolic mitral ring tissue velocity (...

King, Gerard J.

2005-01-01

340

Reactive Collision Avoidance for Unmanned Aerial Vehicles using Doppler Radar  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

 
 
 
 
341

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

342

Prediction of cerebrovascular reserve by the MRI and doppler ultrasonography  

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-07-15

343

Meckel's Diverticulum: Doppler Ultrasound and the tree sign  

International Nuclear Information System (INIS)

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

344

Scanning Doppler lidar applications for air quality monitoring  

Science.gov (United States)

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

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

2014-05-01

345

Duplex colour Doppler sonography — role in neck metastasis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present study was done to evaluate the rote of Duplex colour Doppler Sonography in neck metastasis. 30 patients with primary head and neck cancer were evaluated by Duplex colour Doppier sonography and results analysed. In more than 95% of cases, the vascular status could be established before any form of therapy was instituted. Compression and infiltration of carotids and internal jugular vein (IJV) could be demonstrated and a structured and dynamic relationship of metastatic nodes to the...

Puri, R.; Srinath, V. S.; Chakravarti, A. L.

2002-01-01

346

Doppler Global Velocimetry of F/A-18  

Science.gov (United States)

The laser light sheet visualization of the vortical flow was part of a Doppler Global Velocimetry (DGV) measurement system. The DGV system is capable of simultaneously measuring three-components of velocity within the measurement plane illuminated by the laser light sheet. The investigation of the flow above the F/A-18 model was the first use of the technique to measure the flow about an aircraft configuration.

1991-01-01

347

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

348

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

349

Doppler-free resonance ionization mass spectrometry of beryllium  

International Nuclear Information System (INIS)

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

350

Cross sectional early mitral flow velocity profiles from colour Doppler.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Instantaneous cross sectional flow velocity profiles from early mitral flow in 10 healthy men were constructed by time interpolation of the velocity data from each point in sequentially delayed two dimensional digital Doppler ultrasound maps. This interpolation allows correction of the artificially produced skewness of velocities across the flow sector caused by the time taken to scan the flow sector for velocity recording of pulsatile blood flow. These results suggested that early mitral flo...

Samstad, S. O.; Torp, H. G.; Linker, D. T.; Rossvoll, O.; Skjaerpe, T.; Johansen, E.; Kristoffersen, K.; Angelsen, B. A.; Hatle, L.

1989-01-01

351

The coincidence spectrometer of Doppler broadening of annihilation line  

Energy Technology Data Exchange (ETDEWEB)

A Doppler broadening spectrometer with the reduction of background based on standard electronics is presented. The peak to background ratio achieved for the annihilation line is about 470:1 at 530 keV. It allows us to clearly observe positron annihilation with core electrons. As examples of the work of the spectrometer preliminary measurements of positron annihilation with core electrons in Mg-Cd, in uranium and nickel are presented. (author). 8 refs, 4 figs.

Dryzek, J.; Dryzek, E. [Institute of Nuclear Physics, Cracow (Poland)

1997-10-01

352

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

353

Imaging nanoparticle flow using magneto-motive optical Doppler tomography  

Science.gov (United States)

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, \

Kim, Jeehyun; Oh, Junghwan; Milner, Thomas E.; Nelson, J. Stuart

2007-01-01

354

Doppler images of DI Piscium during 2004-2006  

Science.gov (United States)

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

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

2014-02-01

355

Ultrasonic Doppler measurement of renal artery blood flow  

Science.gov (United States)

An extensive evaluation of the practical and theoretical limitations encountered in the use of totally implantable CW Doppler flowmeters is provided. Theoretical analyses, computer models, in-vitro and in-vivo calibration studies describe the sources and magnitudes of potential errors in the measurement of blood flow through the renal artery, as well as larger vessels in the circulatory system. The evaluation of new flowmeter/transducer systems and their use in physiological investigations is reported.

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

1975-01-01

356

Analytical theory of Doppler reflectometry in slab plasma model  

International Nuclear Information System (INIS)

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

357

Doppler ultrasonography of hepatic artery in malignant liver tumors  

Directory of Open Access Journals (Sweden)

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

Periši? Mirjana

2008-01-01

358

Study of retrobulbar hemodynamics in diabetes via color doppler ultrasound  

Directory of Open Access Journals (Sweden)

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

Wei Chen

2014-09-01

359

Ion Doppler Measurements in the HIT--II Spherical Torus  

Science.gov (United States)

An Ion Doppler Spectrometer (IDS) has been used to diagnose plasmas in the Helicity Injected Torus (HIT--II) experiment. The IDS instrument uses a linear array optical fiber and a telescope, which is mountable on several mid-plane and axial ports on the HIT--II device, to obtain collimated light along a single line-of-sight chord. The 1 m spectrometer (with a resolution of 0.09 Åuses a 16-channel-PMT array, to obtain chord-averaged toroidal flow velocity from Doppler shifting and ion temperature from Doppler broadening of particular emission lines from impurity ion species (e.g., Ouc(V,) Cuc(III,) Buc(IV).) IDS data from repeatable discharges, taken using chords with various impact parameters, can be used to generate radial profiles of toroidal flow velocity, ion temperature and emission intensity for each species. The IDS instrument has been used to study both Ohmic and Coaxial Helicity Injection (CHI) discharges in the HIT--II device, with sets of CHI discharges taken with anode and cathode central column injector polarities, and Ohmic discharges in both single- and double-null divertor configurations. Results obtained from IDS will be presented, and the implications for current drive will be discussed.

Gu, P.; Jarboe, T. R.; Nelson, B. A.; Redd, A. J.; Smith, R. J.; Nagata, M.; Uyama, T.

2002-11-01

360

Active Region Moss: Doppler Shifts from Hinode/EIS Observations  

CERN Document Server

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

Tripathi, Durgesh; Klimchuk, James A

2012-01-01

 
 
 
 
361

[Usefulness of transvaginal Doppler color in ovarian neoplasms diagnosis].  

Science.gov (United States)

The vascular resistant evaluation by Doppler waveform is a method used in clinic and research. The neoplastic malignant has an increased growth with an increased amount of neomalignant vessels. The presence of these vessels produce an increase of the transversal section area from the tumoral vascular system, therefore there is a decrease in the vascular resistance. The main objective of this work is to show the usefulness of Doppler waveform as predictor factor of malignity in ovary tumors. Eighteen patients with tumoral mass in the ovary were studied. They were between 21 and 67 years old (mean = 43). The tumoral volume and the flow resistance of blood vessels which irrigated those tumoral mass were evaluated by transvaginal ultrasound with color and pulsed Doppler. The pulsatility index (SD/media) was used. The Chi cuadrado test was used to evaluate the results. The results show the presence of six malignant tumors, three of them with low malignicity and the presence of twelve benign tumors. The age of the patients between both groups (malignant and benign tumors) were significant different (40.7 versus 52 years old, p < 0.001). The mean tumoral volume was 65 ml, with a range of 17 to 225 ml in the group of patients with benign tumors and the mean tumoral volume from patients with malignant tumors was 951 ml with a range of 141 to 3142 ml. The difference in the tumoral in both groups was significative with p < 0.001.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8209049

Muñoz, H; Martínez, L; Parra, M; Cunill, E; Polanco, M; Leible, S; Romero, C

1993-01-01

362

Estimation of Carotid Artery Pulse Wave Velocity by Doppler Ultrasonography  

Directory of Open Access Journals (Sweden)

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

Mehdi Maerefat

2009-06-01

363

Diagnostic sensitivity and specificity of Doppler ultrasound in rheumatoid arthritis  

DEFF Research Database (Denmark)

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

Terslev, L.; Recke, P. von der

2008-01-01

364

Color Doppler in the Assessment of Uteroplacental Circulation Insufficiency  

Directory of Open Access Journals (Sweden)

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

Ahmad Soltani Shirazi

2011-05-01

365

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

366

New signal analysis methods for laser doppler flowmetric recordings  

Science.gov (United States)

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

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

2014-01-01

367

Doppler spectra of the UHF diffuse radio aurora  

International Nuclear Information System (INIS)

A large number of radar backscatter Doppler spectra from the 398-MHz phased array at Homer, Alaska, have been analyzed for representative periods of widespread, long-lasting radar echoes in the premidnight and postmidnight sectors. Spectra corresponding to type 1 and type 2 echoes were observed. The type 1 spectra were most evident in the postmidnight data, where they appeared as velocity plateaus in azimuthal scans at the farther ranges. The type 2, low-velocity spectra were generally observed only in the absence of type 1 echoes. The spectral widths if the type 2 spectra were consistent with decay rates estimated by linear theory, as might be expected for dissipative waves at the short-wavelength end of a turbulent cascade. The velocity plateaus and other features of the azimuthal and range variation of Doppler velocity can be understood if the auroral electrojet is assumed to have moderate variations in direction on a scale of tens of kilometers. It was possible to obtain from the Doppler data qualitative estimates of the electric field, whose variation in time and latitude was in general agreement with the model electrojet configuration of Kamide and Vickrey (1983)

368

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

369

Active Region Moss: Doppler Shifts from Hinode/EIS Observations  

Science.gov (United States)

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

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

2012-01-01

370

Transthoracic ultrafast Doppler imaging of human left ventricular hemodynamic function.  

Science.gov (United States)

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

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

2014-08-01

371

Uranium dioxide crystalline binding effect on Doppler broadening  

International Nuclear Information System (INIS)

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

372

Measurement of colonic blood flow with laser Doppler flowmetry.  

Science.gov (United States)

Colonic blood flow was measured with laser Doppler flowmetry during operation in 62 patients and during coloscopy in 15 patients. In 18 subjects mucosal and serosal laser Doppler signals were compared during 'resting' conditions, vascular occlusion, and reactive hyperemia. The mucosal (n = 36) and serosal (n = 36) flowmeter signals were of the same order of magnitude throughout the whole range of flowmeter signals (r = 0.96; p less than 0.001). In eight subjects total venous outflow from a colonic segment was measured simultaneously with flowmeter recordings from the serosal side. A correlation coefficient of 0.95 (n = 46; p less than 0.001) was obtained between total intestinal blood flow and serosal flowmeter signal during 'resting' and reduced blood flows. In this flow range a calibration curve was constructed for interpretation of the flowmeter signals in absolute flow units. The wall thickness of the bowel determined the quantitative relationship between flowmeter signal and total intestinal blood flow. It is concluded that laser Doppler flowmetry represents a potentially very interesting non-invasive, continuous method for the quantitative study of human intestinal blood flow. PMID:2946071

Ahn, H; Lindhagen, J; Lundgren, O

1986-09-01

373

Color doppler flow mapping of prosthetic heart valves  

International Nuclear Information System (INIS)

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

374

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.

375

Portal Doppler ultrasound evaluation in myelitis by Schistosoma mansoni Avaliação pela ultrassonografia com Doppler portal na mielite pelo Schistosoma mansoni  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The mechanism for development of schistosomal myelitis has not yet been completely understood. Few publications have tried to establish a link between the general clinical presentation of the illness and its neurological manifestations. Objective: To evaluated the portal blood flow in patients with schistosomal myelitis and controls. Method: Forty-three individuals were evaluated using portal Doppler ultrasound. Group I consisted of 13 patients with the spinal form of schistosomiasis. Group I...

Claudio Henrique Fernandes Vidal; Fernando Viana Gurgel; Maria Lucia Brito Ferreira; Ana Lúcia Coutinho; Hildo Rocha Cirne de Azevedo Filho

2010-01-01

376

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

International Nuclear Information System (INIS)

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

377

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)

378

[Transesophageal, anatomic and Doppler echocardiography. Technic, indications, interpretation].  

Science.gov (United States)

Cardiac ultrasonography completed by the Doppler technique has demonstrated his ability to visualize almost all of the anatomical pathology including description and semi-quantification of pathological blood flows within the heart. However, the physical properties of the ultrasound beam frequently limit the imaging process and Doppler flow studies. Absorption of ultrasound by the chest wall is a major determinant of quality and hence interpretation, together with the depth of the examined zone of interest. It's a common finding that echo-Doppler images are better in children than in obese adults. Moreover, strong echo-reflectors, such as calcification or prosthetic heart valves, create large acoustic shadowing effects behind which obtaining an ultrasound signal is difficult if not impossible. For this reason transesophageal echocardiography represents a new essential window into the heart. By positioning a transducer mounted on a fibroscopy sheath into the esophagus in close contact with the left atrium, images of unequaled quality are obtained. An image-resolution of the order of 1-2 mm explains the diagnostic quality in infectious aortic and mitral valve diseases for assessing small vegetations, annular abscesses, and regurgitant lesions by adding color-coded Doppler. The investigation of prosthetic valves dysfunction is completely renewed for detecting disinsertion and thromboses. Heart screening for systemic emboli includes mandatory how the visualization of left (and also right) auricles and the interatrial septum associated with contrast study. Lesions of the descending aorta (aneurysms, thromboses and especially dissections) are perfectly documented in combination with color-Doppler indicating true and false channels as well as re-entry sites. Lastly, other applications are being developed including global and segmental myocardial contractility at rest or even at stress, although this last application is still at the experimental stage. Transesophageal echocardiography therefore appears to constitute a real revolution as an added possibility to the cardiological use of ultrasound: the indication for this "window" being decided for the preferential cases described above only after having performed a standard echo examination. Very often, the indication will be raised by the echocardiographer who, after performing a conventional echo may consider that better or supplementary information could be obtained via the esophageal route. This technique performed by trained operators, is relatively simple, minimally traumatic and can be performed on an outpatient basis provided certain precautions, imposed by the preparation and the consequences of premedication received by the patient, are respected. PMID:2589811

Scheublé, C; Castillo-Fenoy, A

1989-09-30

379

Aspectos psicológicos y Doppler-Duplex dinámico en disfunción eréctil / Psychological features and Doppler-Duplex in erectile disfunction  

Scientific Electronic Library Online (English)

Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Objetivo: Relacionar los hallazgos de la ecografía Doppler-Duplex color tras la inyección intracavernosa de prostaglandina con los aspectos psicológicos en pacientes con disfunción eréctil (DE). Material y método: Se estudiaron, de forma prospectiva, 42 pacientes con DE mediante ecografía Doppler-Du [...] plex color tras la inyección de 20 microgramos de PGE1 intracavernosa. Se evaluaron los patrones morfodinámicos y de flujo. Se graduó visualmente la tumescencia peneana en pobre, moderada o buena (I, II, III). Todos los pacientes completaron el Índice Internacional de Función Eréctil (IIFE). Para el estudio psicológico de los pacientes se utilizó el examen Internacional de los Trastornos de la Personalidad (IPDE, módulo CIE-10) y Symptom Checlist 90-Revised (SCL-90R). Resultados: 29 pacientes (69.05%) mostraron una respuesta normal en el estudio ecográfico (velocidad picosistólica >30 cm/s; velocidad telediastólica negativa o Abstract in english Objectives: To establish a relationship between Doppler-Duplex colour ultrasound after prostaglandin intracorporeal injection and psychological features in patients suffering from erectile dysfunction. Methods: Forty two patients with erectile dysfunction were prospectively evaluated with Doppler-Du [...] plex colour ultrasonography after intracavernosal injection of 20 micrograms of E1 prostaglandin. Dynamic vascular pattern were analyzed and penile tumescence were graded in poor, moderate or good (I, II, III). All of them completed the International Index of Erectile Dysfunction, International Exam of Personality Traits (IPDE) and the Symptom Checklist (SCL-90). Results: 29 patients (69.05%) showed a normal ultrasonography response (Peak Systolic Velocity >30 cm/s; Telediastolic velocity negative or less than 5cm/s and penile tumescence grade III) and were classified as good responders with probably psychogenic erectile dysfunction. Patients who did not show these values were classified in the group of erectile dysfunction of vascular origin. We found significative differences between the two groups in sex desire, tumescence and paranoid personality. The more frequent personality features were paranoid and squizoid (excentric) and ananchastic and anxious (fearful ones). Somatization and obsessive-compulsive symptoms have been outlined over the rest. We have found that paranoid personality is sixteen times more frequent in patients with normal ultrasonography. Conclusions: Psychological features and dysfunctional personality traits accompany psychogenic and organic erectile dysfunction, thus it is thought that mixed aetiology coexist in this patients. Doppler-Dupplex Colour ultrasound is an useful method to exclude organic vascular factors. On de basis of our article, is more common to find psychological discomfort and dysfunctional personality traits in patients with normal ultrasound, which may help in their diagnosis and treatment.

M.A., Fernández-Gil; L., Martínez-Piñeiro; M., Martí; F.J., Vaz Leal; J.A., Guisado Macías.

380

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

Science.gov (United States)

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

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

2006-01-01

 
 
 
 
381

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Danielsen, R.; Stangeland, L.; Vik-mo, H.

1988-01-01

382

A new active cavitation mapping technique for pulsed HIFU applications-bubble doppler.  

Science.gov (United States)

In this work, a new active cavitation mapping technique for pulsed high-intensity focused ultrasound (pHIFU) applications termed bubble Doppler is proposed and its feasibility is tested in tissue-mimicking gel phantoms. pHIFU therapy uses short pulses, delivered at low pulse repetition frequency, to cause transient bubble activity that has been shown to enhance drug and gene delivery to tissues. The current gold standard for detecting and monitoring cavitation activity during pHIFU treatments is passive cavitation detection (PCD), which provides minimal information on the spatial distribution of the bubbles. B-mode imaging can detect hyperecho formation, but has very limited sensitivity, especially to small, transient microbubbles. The bubble Doppler method proposed here is based on a fusion of the adaptations of three Doppler techniques that had been previously developed for imaging of ultrasound contrast agents-color Doppler, pulse-inversion Doppler, and decorrelation Doppler. Doppler ensemble pulses were interleaved with therapeutic pHIFU pulses using three different pulse sequences and standard Doppler processing was applied to the received echoes. The information yielded by each of the techniques on the distribution and characteristics of pHIFU-induced cavitation bubbles was evaluated separately, and found to be complementary. The unified approach-bubble Doppler-was then proposed to both spatially map the presence of transient bubbles and to estimate their sizes and the degree of nonlinearity. PMID:25265178

Li, Tong; Khokhlova, Tatiana; Sapozhnikov, Oleg; O'Donnell, Matthew; Hwang, Joo

2014-10-01

383

Data Quality Control for Vessel Mounted Acoustic Doppler Current Profiler. Application for the Western Mediterranean Sea  

Science.gov (United States)

A systematic Data Quality Checking Protocol for vessel Mounted Acoustic Doppler Current Profiler observations is proposed. Previous-to-acquisition conditions are considered along with simultaneous ones.

Garcia-Gorriz, E.; Front, J.; Candela, J.

1997-01-01

384

High resolution Doppler lidar based on actively stabilized ring dye laser  

International Nuclear Information System (INIS)

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

385

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

386

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

Directory of Open Access Journals (Sweden)

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

Edip Hatipo?lu

2008-01-01

387

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

CERN Document Server

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

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

2007-01-01

388

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

389

Assessment of resistive index in acute epididymitis on doppler sonography  

International Nuclear Information System (INIS)

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

390

Implementation of on-the-fly doppler broadening in MCNP  

International Nuclear Information System (INIS)

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

391

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

392

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

393

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

394

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

395

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

396

Doppler global velocimetry - A new way to look at velocity  

Science.gov (United States)

A new laser velocimetry technique, Doppler global velocimetry, is described. This technique is capable of simultaneously measuring in real time the three components of velocity of an entire particle field illuminated by a laser light sheet. A prototype one-component velocimeter is described along with the signal processing electronics. The system was tested by measuring the velocity field from a rotating wheel and a small subsonic jet flow in the laboratory. The first wind tunnel test measured the vortical velocity field above a delta wing. The results are presented and compared with fringe-type laser velocimeter and five-hole probe data.

Meyers, James F.; Komine, Hiroshi

1991-01-01

397

Doppler Global Velocimetry: A New Way to Look at Velocity  

Science.gov (United States)

A new laser velocimetry technique, Doppler global velocimetry, is described. This technique is capable of simultaneously measuring in real time the three components of velocity of an entire particle field illuminated by a laser light sheet. A prototype one-component velocimeter is described along with the signal processing electronics. The system was tested by measuring the velocity field from a rotating wheel and a small subsonic jet flow in the laboratory. The first wind tunnel test measured the vortical velocity field above a delta wing. The results are presented and compared with fringe-type laser velocimeter and five-hole probe data.

Meyers, James F.; Komine, Hiroshi

1991-01-01

398

A two color, dual beam backscattering laser Doppler velocimeter  

Science.gov (United States)

A laser Doppler velocimeter has been developed which uses two of the colors emitted from an argon ion laser for the simultaneous measurement of orthogonal velocities. Designed for use in a 2.13 m by 3.05 m wind tunnel, it is capable of traversing its focal volume across spatially unstable flows at scan speeds of up to 1.15 m/sec. Its optical layout and principles of operation are discussed and the data from a typical traversal of a trailing wing tip vortex are presented.

Grant, G. R.; Orloff, K. L.

1973-01-01

399

Two-color dual-beam backscatter laser Doppler velocimeter  

Science.gov (United States)

A laser Doppler velocimeter has been developed that uses two of the colors emitted from an argon-ion laser for the simultaneous measurement of orthogonal velocities. Designed for use in a 2.13- by 3.05-m wind tunnel, it is capable of traversing its focal volume across spatially unstable flows at scan speeds of up to 1.5 m/sec. Its optical layout and principles of operation are discussed, and the data from a typical traversal of a trailing wing-tip vortex are presented.

Grant, G. R.; Orloff, K. L.

1973-01-01

400

Airborne Doppler lidar techniques for observing severe thunderstorms  

Science.gov (United States)

On 30 June 1981 the wind fields around an Oklahoma severe thunderstorm were observed in detail using an airborne Doppler lidar operated by NASA. Desipte uncertainties caused by inertial navigation errors and problems in sampling some of the aircraft attitude and motion parameters, reasonably clear picures of the distributions of relative reflectivity, horizontal wind velocity, and velocity spectral width near the cloud base have been obtained. Aspects of the design and functioning of the NASA lidar relevant to the collection and analysis of the data are described.

Mccaul, E. W., Jr.; Bluestein, H. B.; Doviak, R. J.

1986-01-01

 
 
 
 
401

NASA airborne Doppler lidar program: Data characteristics of 1981  

Science.gov (United States)

The first flights of the NASA/Marshall airborne CO2 Doppler lidar wind measuring system were made during the summer of 1981. Successful measurements of two-dimensional flow fields were made to ranges of 15 km from the aircraft track. The characteristics of the data obtained are examined. A study of various artifacts introduced into the data set by incomplete compensation for aircraft dynamics is summarized. Most of these artifacts can be corrected by post processing, which reduces velocity errors in the reconstructed flow field to remarkably low levels.

Lee, R. W.

1982-01-01

402

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

403

Approximation of the Doppler broadening function by Frobenius method  

International Nuclear Information System (INIS)

An analytical approximation of the Doppler broadening function ?(x,?) is proposed. This approximation is based on the solution of the differential equation for ?(x,?) using the methods of Frobenius and the parameters variation. The analytical form derived for ?(x,?) in terms of elementary functions is very simple and precise. It can be useful for applications related to the treatment of nuclear resonances mainly for the calculations of multigroup parameters and self-protection factors of the resonances, being the last used to correct microscopic cross-sections measurements by the activation technique. (author)

404

Improved Prediction of the Doppler Effect in TRISO Fuel  

Energy Technology Data Exchange (ETDEWEB)

The Doppler feedback mechanism is a major contributor to the passive safety of gas-cooled, graphite-moderated High Temperature Reactors that use fuel based on TRISO particles. It follows that the correct prediction of the magnitude and time-dependence of this feedback effect 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 transfer and temperature rise must be correctly predicted. This paper presents an improved model for the TRISO particle and its thermal behavior during transients. The improved approach incorporates an explicit TRISO heat conduction model to better quantify the time dependence of the temperature in the various layers of the TRISO particle, including its fuel central zone. There follows a better treatment of the Doppler Effect within said fuel zone. The new model is based on a 1-D analytic solution for composite media using the Green’s function technique. The modeling improvement takes advantage of some of the physical behavior of TRISO fuel under irradiation and includes a distinctive look at the physics of the neutronic Doppler Effect. The new methodology has been implemented within the coupled R-Z nodal diffusion code CYNOD-THERMIX. The new model has been applied to the analysis of earthquakes (presented in a companion paper). In this paper, the model is applied to the control rod ejection event, as specified in the OECD PBMR-400 benchmark, but with temperature dependent thermal properties. The results obtained for this transient using the enhanced code are a considerable improvement over the predictions of the original code. The incorporation of the enhanced model shows that the Doppler Effect plays a more significant role than predicted by the original unenhanced model based on the THERMIX homogenized fuel region model. The new model shows that the overall energy generation during the rod ejection transient is significantly lower than predicted by the unenhanced model. The fuel temperature reaches a slightly higher maximum, but at no time does it approach the nominal allowable TRISO fuel temperature. The analyses with the enhanced model also show that the reactor period during the cool down is larger than previously predicted with the homogenous fuel region model.

J. Ortensi; A.M. Ougouag

2009-05-01