WorldWideScience
 
 
1

Comparison of Doppler flow Tei-indexes with pulmonary artery thermodilution measurement of cardiac output in an experimental porcine model.  

UK PubMed Central (United Kingdom)

The objective of our study was to compare Doppler echocardiography imaging with pulmonary artery thermodilution measurement during mechanical ventilation. Total 78 piglets (6 weeks old, average weight 24 kg, under general anesthesia) were divided into 4 groups under different cardiac loading conditions (at rest, with increased left ventricular afterload, with increased right ventricular preload, and with increased afterload of both heart ventricles). At 60 and 120 min the animals were examined by echocardiography and simultaneously pulmonary artery thermodilution was used to measure cardiac output. Tei-indexes data were compared with invasively monitored hemodynamic data and cardiac output values together with calculated vascular resistance indices. A total of 224 parallel measurements were obtained. Correlation was found between values of right Tei-index of myocardial performance and changes in right ventricular preload (p<0.05) and afterload (p<0.01). Significant correlation was also found between left index values and changes of left ventricular preload (p<0.001), afterload (p<0.001), stroke volume (p<0.01), and cardiac output (p<0.01). In conclusion, echocardiographic examination and determination of the global performance selectively for the right and left ventricle can be recommended as a suitable non-invasive supplement to the whole set of methods used for monitoring of circulation and cardiac performance.

Kobr J; T?eška V; Molá?ek J; Kuntscher V; Liška V; Slavík Z

2011-01-01

2

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

Scientific Electronic Library Online (English)

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

Barberato, Silvio Henrique; Pecoits Filho, Roberto

2006-06-01

3

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

International Nuclear Information System (INIS)

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

2005-01-01

4

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

UK PubMed Central (United Kingdom)

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

Yadav DK; Choudhary S; Gupta PK; Beniwal MK; Agarwal S; Shukla U; Dubey NK; Sankar J; Kumar P

2013-08-01

5

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

Directory of Open Access Journals (Sweden)

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

Sava? Özsu; Abdülkadir K?r??; Y?lmaz Bülbül; Funda Öztuna; Kay?han Karaman; Merih Kutlu; Tevfik Özlü

2012-01-01

6

Fetal myocardial performance (Tei) index in fetal hemoglobin Bart's disease.  

UK PubMed Central (United Kingdom)

PURPOSE: To assess the effectiveness of Tei index in differentiating fetal Hb Bart's disease in pregnancies at risk in the first half of pregnancy. MATERIALS AND METHODS: Pregnancies meeting the inclusion criteria were consecutively recruited to the study. The inclusion criteria were as follows: 1) singleton pregnancies, 2) gestational age of 12 - 20 weeks, 3) at risk of Hb Bart's disease, 4) confirmed fetal diagnosis of Hb Bart's disease. Fetuses with frank hydrops fetalis or fetuses with chromosomal abnormalities or structural anomalies were excluded. Tei index was performed and immediately recorded before invasive prenatal diagnosis was performed. RESULTS: Of 152 fetuses, 50 were finally proven to be affected by Hb Bart disease, and the remainder was unaffected. Mean (± SD) Tei index were 0.48 ± 0.07 and 0.54 ± 0.08 in group of unaffected and affected fetuses, respectively. The mean difference was 0.05 which was statistically significant (p < 0.001). Likewise, mean (± SD) isovolumetric contraction time (ICT) in normal fetuses were also significantly different from that of affected fetuses. CONCLUSION: In the first half of pregnancy, Tei index in the fetuses with Hb Bart's disease was significantly higher than that in normal fetuses implying that Tei index may be a novel useful and non-invasive tool for early detection of fetal Hb Bart's disease among pregnancies at risk.

Luewan S; Tongprasert F; Srisupundit K; Tongsong T

2013-08-01

7

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

8

Markup Enhancement: Converting CEE Dictionaries into TEI, and Beyond  

UK PubMed Central (United Kingdom)

This paper describes the process of markup enhancement for six Centraland Eastern European language dictionaries. We provide examplesof the process for the English-Slovene dictionary, currently beingproduced by the Slovene publishing house DZS, and based onthe Oxford-Hachette English-French dictionary. The TEI documenttype for Dictionaries is presented, followed by the process of crosstranslatingfrom original DZS SGML documents into a TEI.dictionarydocument and into HTML. We next discuss the development of a specializedDTD that can serve as a general model for lexical data, andprovide some examples of its use.11 IntroductionThe EU project concede aims to build structured lexical databases derivedfrom existing machine-readable dictionaries, for six languages: Bulgarian,Czech, Estonian, Hungarian, Romanian and Slovene. The project builds onthe experience and resources of the multext-east project [2], which developedan annotated parallel corpus for the same six...

Tomaz Erjavec; Nancy Ide

9

A TEI Encoding of Aligned Corpora as Translation Memories  

UK PubMed Central (United Kingdom)

Sentence level aligned parallel corporaare a basic language resource for multilingualresearch. TEI proposes severalways in which to encode such corpora,but all separate the alignment informationfrom the texts. This article proposesan alternative TEI conformant inplaceencoding of aligned texts, whichis similar to that employed for translationmemories. For research corpora targetedtowards language engineering andterminology/translation studies, we arguethat such an encoding can aid theprocess of corpus acquisition, processingand exploitation.1 IntroductionSentence level aligned parallel corpora are a basiclanguage resource for multilingual research. Agrowing number of parallel corpora are being produced,recent ones including MLCC (Armstronget al., 1998), Crater (McEnery et al., 1997), ENPC(Johansson et al., 1996), and MULTEXT-East(Dimitrova et al., 1998). We are involved in aproject to produce a Slovene-English sentencelevelaligned parallel corpus ...

Tomaz Erjavec

10

TEI-9063, a stable and highly specific prostacyclin analogue for the prostacyclin receptor in mastocytoma P-815 cells.  

UK PubMed Central (United Kingdom)

The prostacyclin (PGI2) analogues, TEI-9063 and its methyl ester, TEI-1324, have been compared with another stable analogue, iloprost, with respect to binding to the PGI2 receptor, stimulation of adenylate cyclase activity and inhibition of thrombin-induced Ca2+ mobilization in mastocytoma P-815 cells. TEI-9063 displaced the [3H]iloprost binding to the membrane fraction, the IC50 value being 3 nM, but showed very low affinity for the PGE receptor. TEI-9063 dose dependently stimulated cAMP formation in the cells and GTP-dependent adenylate cyclase activity in the membrane fraction, the EC50 value being 50 and 10 nM, respectively. Furthermore, TEI-9063 prevented the thrombin-induced increase in the intracellular Ca2+ concentration, the IC50 value being 50 nM. These IC50 and EC50 values are lower than those obtained for iloprost. On the other hand, those of TEI-1324 were about two-orders higher. Although PGI2 lost its ability to stimulate cAMP formation by preincubation for 20 min at 37 degrees C, TEI-9063 completely retained its ability after 60-min preincubation. These results demonstrate that TEI-9063 is a stable and stronger agonist for the PGI2 receptor than iloprost, and that it prevents thrombin-induced Ca2+ mobilization through stimulation of the adenylate cyclase system in mastocytoma cells.

Negishi M; Hashimoto H; Yatsunami K; Kurozumi S; Ichikawa A

1991-09-01

11

Suppression of IgE antibody response in mice by a naphthalene derivative, TEI-6472.  

UK PubMed Central (United Kingdom)

In the present report, we investigated suppressive effects of a naphthalene derivative, (7E)-N-(2-carboxyphenyl)-8-(2-naphthyl)-5,6-trans-5,6-methano-7- octenamide L-lysine salt (TEI-6472), on in vitro and in vivo antigen-specific IgE response. Anti-trinitrophenyl (TNP) IgE response induced in vitro in TNP-keyhole limpet hemocyanin (KLH)-primed murine spleen cells was suppressed by about 60% in the presence of 10(-6) M TEI-6472. On the other hand, anti-TNP IgG1 and IgM response were not significantly suppressed under the same conditions. Proliferative responses of BALB/c spleen cells stimulated by lipopolysaccharide, concanavalin A or allogeneic spleen cells were not inhibited by TEI-6472 at 10(-6)-10(-5) M. Interleukin 4 production from helper T-cell clone, D10.G4.1 was suppressed only slightly (less than 20%) at 10(-6) M TEI-6472. This compound was also effective in suppressing secondary anti-TNP IgE response in mice that were immunized twice with TNP-KLH and alum. When 10-20 mg/kg/day TEI-6472 was administered s.c. for 5 consecutive days starting from one day before the first and the second immunization, secondary anti-TNP IgE response was inhibited most strongly (40-45%). Anti-TNP IgG1 response was also inhibited but to a smaller extent (20-24%), while anti-TNP IgM response was suppressed only slightly (0-15%). These results suggest that, under appropriate conditions, TEI-6472 can suppress IgE responses more preferentially both in vitro and in vivo.

Ohmori H; Kishimoto T; Hikida M; Hazato A; Kurozumi S

1993-07-01

12

Antitumor activity, optimum administration method and pharmacokinetics of 13,14-dihydro-15-deoxy-deoxy-Delta7 -prostaglandin A1 methyl ester (TEI-9826) integrated in lipid microspheres (Lipo TEI-9826).  

Science.gov (United States)

13,14-Dihydro-15-deoxy-Delta7-prostaglandin A1 methyl ester (TEI-9826), an antitumor prostaglandin analog, is a candidate for clinical trial. In the present study, we examined its biological stability in vitro, antitumor activity in vitro and in vivo, and pharmacokinetics. Although TEI-9826 was rapidly hydrolyzed to the carboxylic acid form (TOK-4528), TOK-4528 as well as Delta12-prostaglandin J2 (PGJ2) were found to be stable in rat, mouse and human serum in vitro. TEI-9826 exhibited nearly identical or greater potential antitumor activity compared to Delta12-PGJ2 and Delta7-PGA1 in vitro against Colon26 tumor cells. Further evaluation of TEI-9826 using the 38 human cancer cell lines panel and COMPARE analysis suggested that its mode of action is quite different from other anticancer agents that are currently used. TEI-9826 was integrated into lipid microspheres (Lipo TEI-9826) for dosing. Growth inhibition by Lipo TEI-9826 against Colon26 tumor inoculated s.c. in mice depended on administration route, i.e. at 80 mg/kg, no growth suppressive effect was observed for daily bolus i.v., but significant growth suppressive effect was observed for daily i.p., daily s.c. every other day s.c. and 4 times a day continuous (5 min) i.v. These tumor growth-suppressive effects were cytostatic and the tumor started to regrow at the end or a few days after the end of administration. The pharmacokinetic study suggested that maintaining the blood level of TEI-9826 and/or TOK-4528 was essential for their antitumor effects. These results show that continuous i.v. infusion might be the most suitable administration method of Lipo TEI-9826 for clinical trial. PMID:11290870

Fukushima, S; Takeuchi, Y; Kishimoto, S; Yamashita, S; Uetsuki, K; Shirakawa, S; Suzuki, M; Furuta, K; Noyori, R; Sasaki, H; Kikuchi, Y; Kita, T; Yamori, T; Sawada, J; Kojima, M; Hazato, A; Kurozumi, S; Fukushima, M

2001-03-01

13

Open E-book vs. TEI-lite; ebook standards compared  

UK PubMed Central (United Kingdom)

This paper compares two leading XML markup sets for electronic book publishing. TEIlitehas for several years been the default markup for scholarly text archive projects.Open-Ebook is an industry-developed standard currently championed by Microsoft. Thispaper examines the two in terms of their views of document architecture, metadata, andimplementation. It also examines issues in the automatic conversion of documentsmarked up with TEI- lite to Open-Ebook.BackgroundThe experiences of researchers developing full- text databases over the past two or moredecades has led first to a decision on the part of much of the academic community tostandardize on SGML (and now XML-based) markup [Barnard, David, et al.], andsecond to the development of a common document type definition (DTD) for scholarlytexts via the Text Encoding Initiative (TEI) project [Sperberg-McQueen and Burnard1994]. The requirement that this common DTD meet the needs of all types of projectsmeans that (at about 1,...

John A. Lehman

14

Doppler Effect  

Science.gov (United States)

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

Cosi

2009-01-01

15

Enhancement of in vitro mineralization in human osteoblasts by a novel prostaglandin A1 derivative TEI-3313.  

UK PubMed Central (United Kingdom)

Human osteoblasts derived from long bone periosteum were induced to mineralize in culture in the presence of 2 mM alpha-glycerophosphate, with typical characteristics of mineralization, namely, accumulation of hydroxyapatite and increases in alkaline phosphatase activity and in osteocalcin production. Mineralization was also enhanced by 10(-8) M 1 alpha, 25-dihydroxyvitamin D3. In this system, a prostaglandin A1 derivative, TEI-3313, with the chemical structure 5-[(Z,2E)-4,7-dihydroxy-2-heptenyridene]-4-hydroxy-2-methylthio-4- (4- phenoxybutyl)-2-cyclopentenone, was found to enhance mineralization as effectively as 1 alpha, 25-dihydroxyvitamin D3, although its potency was 10 times lower than that of the vitamin D3 metabolite. Osteocalcin, a bone-specific noncollagenous matrix protein, accumulated onto the cell layers by treatment with TEI-3313 to a much greater extent than those released into the culture medium. TEI-3313 also enhanced collagen synthesis. Based on the finding that TEI-3313 enhanced the synthesis of both collagen and noncollagenous protein, it is speculated that TEI-3313 enhanced the mineralization by stimulating the expression of various genes in osteoblasts.

Koshihara Y; Takamori R; Nomura K; Sugiura S; Kurozumi S

1991-09-01

16

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

International Nuclear Information System (INIS)

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

1992-01-01

17

Basic doppler echocardiography  

Energy Technology Data Exchange (ETDEWEB)

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

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

1986-01-01

18

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

Directory of Open Access Journals (Sweden)

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

Mitra Kazemi Jahromi; Ali Shahriari Ahmadi; Kaveh Mousavi Kani

2011-01-01

19

Structural analysis of an MK2-inhibitor complex: insight into the regulation of the secondary structure of the Gly-rich loop by TEI-I01800.  

UK PubMed Central (United Kingdom)

Mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2 or MK2) is a Ser/Thr kinase from the p38 mitogen-activated protein kinase signalling pathway and plays an important role in inflammatory diseases. The crystal structure of the complex of human MK2 (residues 41-364) with the potent MK2 inhibitor TEI-I01800 (pK(i) = 6.9) was determined at 2.9 A resolution. The MK2 structure in the MK2-TEI-I01800 complex is composed of two domains, as observed for other Ser/Thr kinases; however, the Gly-rich loop in the N-terminal domain forms an alpha-helix structure and not a beta-sheet. TEI-I01800 binds to the ATP-binding site as well as near the substrate-binding site of MK2. Both TEI-I01800 molecules have a nonplanar conformation that differs from those of other MK2 inhibitors deposited in the Protein Data Bank. The MK2-TEI-I01800 complex structure is the first active MK2 with an alpha-helical Gly-rich loop and TEI-I01800 regulates the secondary structure of the Gly-rich loop.

Fujino A; Fukushima K; Namiki N; Kosugi T; Takimoto-Kamimura M

2010-01-01

20

Structural analysis of an MK2-inhibitor complex: insight into the regulation of the secondary structure of the Gly-rich loop by TEI-I01800.  

Science.gov (United States)

Mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2 or MK2) is a Ser/Thr kinase from the p38 mitogen-activated protein kinase signalling pathway and plays an important role in inflammatory diseases. The crystal structure of the complex of human MK2 (residues 41-364) with the potent MK2 inhibitor TEI-I01800 (pK(i) = 6.9) was determined at 2.9 A resolution. The MK2 structure in the MK2-TEI-I01800 complex is composed of two domains, as observed for other Ser/Thr kinases; however, the Gly-rich loop in the N-terminal domain forms an alpha-helix structure and not a beta-sheet. TEI-I01800 binds to the ATP-binding site as well as near the substrate-binding site of MK2. Both TEI-I01800 molecules have a nonplanar conformation that differs from those of other MK2 inhibitors deposited in the Protein Data Bank. The MK2-TEI-I01800 complex structure is the first active MK2 with an alpha-helical Gly-rich loop and TEI-I01800 regulates the secondary structure of the Gly-rich loop. PMID:20057052

Fujino, Aiko; Fukushima, Kei; Namiki, Naoko; Kosugi, Tomomi; Takimoto-Kamimura, Midori

2009-12-21

 
 
 
 
21

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

2009-01-01

22

Doppler flowmeter  

Energy Technology Data Exchange (ETDEWEB)

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

23

The doppler ultrasound. La ecografia Doppler  

Energy Technology Data Exchange (ETDEWEB)

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.

Contreras Cecilia, E.; Lozano Setien, E.; Hernandez Montero, J.; Ganado Diaz, T.; Jorquera Moya, M.; Blasco Pascual, E. (Hospital Universitario San Carlos. Madrid (Spain))

1994-01-01

24

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.)

2009-01-01

25

Comparison of Cardiac Function by 2 Methods of Echocardiography: Conventional and MPI (Tei Index)  

Directory of Open Access Journals (Sweden)

Full Text Available CHD including LV volume overload may cause alteration in cardiac functions. Echocardiography could detect systolic and diastolic dysfunction using several echo indices. We performed a comparison between 2 different methods (standard and MPI) in echocardiography to detect cardiac dysfunction in abovementioned diseases. This study was of descriptive and analytic type. We studied 35 patients with left to right shunt such as VSD and PDA and valvular insufficiency such as MR and AI. We consider other 20 healthy people as control group to find normal range of MPI. Echo was performed in case group using standard method (systolic: Cardiac Index, mVCF, LVEF by simpson method and diastolic: E, A, E/A, EF slope), MPI and shunt flow by a pediatric cardiologist. In control group only MPI was measured. The data were analyzed by SPSS 13, descriptive statistic, t test, pearson correlation and chisquare. Thirty five patients at an age limit of 1mo to 9yr and sex of 13 female and 22 male were studied. Non of them had systolic and diastolic dysfunction using echocardiographic standard method. MPI was 0. 27±0. 08 in case group which was slightly higher than 0. 27±0. 06 in control group (NS). MPI had slightly positive correlation to shunt flow , male sex , age andweight which was also nonsignificant. MPI (tei index) is of high value in estimation of systolic and diastolic function. It can be used to diagnose cardiac dysfunction a little earlier than standard method.

Fariba Rashidi Ghader; Atieh Makhlough

2008-01-01

26

Image-derived input functions for PET brain studies  

Energy Technology Data Exchange (ETDEWEB)

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 [{sup 11}C]PIB (Pittsburgh Compound-B) ([{sup 11}C]PIB), six repeat (R)-[{sup 11}C]verapamil, and ten single (R)-[{sup 11}C]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)-[{sup 11}C]verapamil, accurate IDIFs were obtained using noncalibrated IDIFs (slope 0.96{+-}0.17; R {sup 2} 0.92{+-}0.07). However, calibration was necessary to obtain IDIFs comparable to the BSIF for both [{sup 11}C]PIB (slope 1.04{+-}0.05; R {sup 2} 1.00{+-}0.01) and (R)-[{sup 11}C]PK11195 (slope 0.96{+-}0.05; R {sup 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 [{sup 11}C]PIB, (R)-[{sup 11}C]verapamil and (R)-[{sup 11}C]PK11195 studies, thereby obviating the need for online arterial sampling. (orig.)

Mourik, Jurgen E.M.; Lubberink, Mark; Berckel, Bart N.M. van; Lammertsma, Adriaan A.; Boellaard, Ronald [VU University Medical Center, Department of Nuclear Medicine and PET Research, P.O. Box 7057, Amsterdam (Netherlands); Schuitemaker, Alie; Tolboom, Nelleke [VU University Medical Center, Department of Nuclear Medicine and PET Research, P.O. Box 7057, Amsterdam (Netherlands); VU University Medical Center, Department of Neurology, Amsterdam (Netherlands)

2009-03-15

27

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

Directory of Open Access Journals (Sweden)

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

MARIA REGINA BUENO FRANCO; DELIA RODRIGUEZ-AMAYA; MARIA HELENA DAMASIO; JOSé LUIZ LLANOS CARRILLO

2009-01-01

28

Laser Doppler Velocimetry.  

Science.gov (United States)

Because it uses light scattering, Doppler shift, and optical heterodyne, laser Doppler velocimetry is an extremely powerful diagnostic technique for the measurement of flow velocity components. Its basic principles, optical arrangements, signal processing...

C. P. Wang

1986-01-01

29

The laser Doppler techniques  

Energy Technology Data Exchange (ETDEWEB)

An attempt is made to give a complete discussion of the principles of velocity measurement by the laser Doppler technique and an adequate description of the instruments and their application. The principles of laser optics are discussed and attention is given to the Doppler shift, the differential Doppler technique, signal processing techniques, directional discrimination and frequency shifting, and the properties of scattering properties. Such applications as studies of turbulence, the measurement of wind speed, and studies of combustion are discussed.

Drain, L.E.

1980-01-01

30

The Doppler moment transform in Doppler tomography  

Science.gov (United States)

The problem of reconstructing two-dimensional vector fields from tomographic measurements based on Doppler techniques is addressed. Measurements are made along lines, from which distributions of the field component parallel to the line are obtained. A new transform, the Doppler moment transform, which extracts local information from such data, is introduced. In contrast to most previous approaches in vector tomography that are only able to treat solenoidal fields, the Doppler moment transform provides information also of the irrotational part of the field. Specifically, it gives rise to partial differential equations in the field components. Properties of the new transform and the corresponding equations are discussed, shedding light on questions of uniqueness. It is also shown that the differential equations can be combined to form algebraic equations in the field components. Finally, a reconstruction scheme is constructed and some numerical experiments are provided.

Andersson, F.

2005-08-01

31

The Doppler Pendulum Experiment  

Science.gov (United States)

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

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

2011-01-01

32

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

2013-01-01

33

Differential doppler heterodyning technique  

DEFF Research Database (Denmark)

Measuring velocity without disturbing the moving object is possible by use of the laser doppler heterodyning technique. Theoretical considerations on the doppler shift show that the antenna property of the photodetector can solve an apparent conflict between two different ways of calculating the detected doppler frequency. It is found that the doppler frequency for this particular setup is independent of the direction of detection. Investigations of the signal-to-noise ratio (SNR) show that the maximum SNR-considering the optical setup-is obtained by measuring the frequency difference between two doppler-shifted beams rather than by measuring the shift of a single beam by comparing it with a reference beam. Measurements seem to be in agreement with the theoretical consideration

Lading, Lars

1971-01-01

34

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

2001-01-01

35

[The Doppler palm test  

UK PubMed Central (United Kingdom)

In 384 hands the patency of the arterial arch was investigated by means of both the Allen test and the Doppler palmar arch test as developed by the authors. While the Allen test is purely subjective and gives a high proportion of false results especially in shocked patients, the Doppler palmar arch test is based on two objective criteria: 1. Demonstration of reversed flow in the distal section of the radial artery on proximal compression. 2. Demonstration of pulsatile flow in the radial thumb artery even on compression of the radial artery. The Doppler palmar arch test eliminates all negative aspects of the Allen test and is therefore definitely more reliable than the latter. It is easy to perform for investigators having little experience with Doppler sonography. The time consumed is not greater than with the Allen test.

Ruland O; Borkenhagen N; Prien T

1988-04-01

36

[The Doppler palm test].  

Science.gov (United States)

In 384 hands the patency of the arterial arch was investigated by means of both the Allen test and the Doppler palmar arch test as developed by the authors. While the Allen test is purely subjective and gives a high proportion of false results especially in shocked patients, the Doppler palmar arch test is based on two objective criteria: 1. Demonstration of reversed flow in the distal section of the radial artery on proximal compression. 2. Demonstration of pulsatile flow in the radial thumb artery even on compression of the radial artery. The Doppler palmar arch test eliminates all negative aspects of the Allen test and is therefore definitely more reliable than the latter. It is easy to perform for investigators having little experience with Doppler sonography. The time consumed is not greater than with the Allen test. PMID:3041584

Ruland, O; Borkenhagen, N; Prien, T

1988-04-01

37

The weighted doppler transform  

CERN Multimedia

We consider the tomography problem of recovering a covector field on a simple Riemannian manifold based on its weighted Doppler transformation over a family of curves $\\Gamma$. This is a generalization of the attenuated Doppler transform. Uniqueness is proven for a generic set of weights and families of curves under a condition on the weight function. This condition is satisfied in particular if the weight function is never zero, and its derivatives along the curves in $\\Gamma$ is never zero.

Holman, Sean

2009-01-01

38

Doppler Effect Applet  

Science.gov (United States)

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

39

Ultrasonic wave Doppler diagnosing apparatus  

UK PubMed Central (United Kingdom)

A Doppler ultrasound diagnostic apparatus equipped with Doppler detection units and a forward/reverse separating means in an audio signal output system, a complex Doppler signal control means which stores a complex Doppler signal received during the Doppler-mode period and reads out said complex Doppler signal during the B-mode period to use as a complex Doppler signal during the B-mode period, wherein said complex Doppler signal control means includes storage means for storing complex Doppler signals that are received during the Doppler-mode period; control means for reading out complex Doppler signals stored in said storage means in a reverse order during the B-mode period; complex frequency inversion means for inverting the frequency of the complex Doppler signals read by said control means in the reverse order from said storage means; and phase rotation correction means for correcting a difference in phase at a moment when the Doppler mode is connected to the B-mode for a complex Doppler signal from said complex frequency inversion means. This decreases deterioration in the quality of a Doppler sound.

IZUMI MIKIO

40

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

Directory of Open Access Journals (Sweden)

Full Text Available La importante presencia de puertos deportivos en las costas gallegas y las previsiones de crecimiento en la oferta de plazas de atraque invitan a la reflexión sobre su incidencia en el bienestar de la sociedad. Es por esto que la incorporación en el análisis coste-beneficio de los costes sociales asociados resulta útil y necesaria para una asignación eficiente de los recursos disponibles. En este artículo se empleó el método de valoración contingente para estimar la disposición al pago (DAP) o variación compensatoria de los residentes por un plan de regeneración del litoral frente al proyecto de ampliación de un puerto deportivo en Punta Lagoa en Teis (Vigo). Para el análisis de las respuestas se empleó un modelo paramétrico y uno no paramétrico, que no precisa asumir ninguna forma funcional de la distribución de la disposición al pago. Las estimaciones obtenidas muestran una DAP de 48 /hogar y de 34 /hogar, respectivamente. De estos resultados se deriva que el plan de regeneración del litoral llevaría consigo una ganancia de bienestar social respecto de la ampliación del puerto deportivo o, lo que es lo mismo, que existe un coste social asociado a este último. Al mismo tiempo, a la luz de los resultados y ante las ventajas que ofrece el estimador Turnbull, se recomienda un mayor empleo de los métodos no paramétricos para obtener estimadores a partir de datos de valoración contingente.

ROI DURÁN MEDRAÑO; MARÍA XOSÉ VÁZQUEZ RODRÍGUEZ

2009-01-01

 
 
 
 
41

Doppler Effect Model  

Science.gov (United States)

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

Duffy, Andrew

2010-04-25

42

Doppler cooling a microsphere  

CERN Document Server

Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

Barker, P F

2010-01-01

43

Comparison of pulse subtraction Doppler and pulse inversion Doppler.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, a new Doppler technique based on pulse subtraction imaging (PSD) is described and compared with pulse inversion Doppler (PID). Combining a nonlinear contrast agent imaging technique with a Doppler process provides a tool for detecting motion of both contrast agents and tissues. This h...

Mahue, V; Mari, JM; Eckersley, RJ; Tang, MX

44

Study on Doppler effect  

International Nuclear Information System (INIS)

[en] A critical examination of experimental works was carried out on check-up of the formula for the Doppler effect in the form ?=?0(1-? cos 0)/?1-?2. A series of measurements was done, the results of which show that the classical formula for the Doppler effect ?=?0(1-? cos 0) takes place. It is supposed that in this case, as well as for operation of ondulators, the transition from the first expression to the second one should be performed by the transformation of the coordinate system. 13 refs.; 9 figs.; 1 tab

1991-01-01

45

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

46

Deconvoluting double doppler spectra  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The successful deconvolution of data from Double Doppler Broadening of Annihilation Radiation (D-DBAR) Spectroscopy is a promising area of endeavour aimed at producing momentum distributions of a quality comparable to those of the angular correlation technique. The deconvolution procedure we test in...

Ho, KF; Ng, KP; Beling, CD; Fung, S; Chan, KL; Tang, HW

47

Photonic doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

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.

Lowry, M E; Molau, N E; Sargis, P D; Strand, O T; Sweider, D

1999-01-01

48

Imaging laser Doppler velocimetry  

Science.gov (United States)

Imaging laser Doppler velocimetry (ILDV) is a novel flow measurement technique, which enables the measurement of the velocity in an imaging plane. It is an evolution of heterodyne Doppler global velocimetry (HDGV) and may be regarded as the planar extension of the classical dual-beam laser Doppler velocimetry (LDV) by crossing light sheets in the flow instead of focused laser beams. Seeding particles within the flow are illuminated from two different directions, and the light scattered from the moving particles exhibits a frequency shift due to the Doppler effect. The frequency shift depends on the direction of the illumination and the velocity of the particle. The superposition of the two different frequency-shifted signals on the detector creates interference and leads to an amplitude modulated signal wherein the modulation frequency depends on the velocity of the particle. This signal is detected using either a high-speed camera or alternatively a smart pixel imaging array. This detector array performs a quadrature detection on each pixel with a maximum demodulation frequency of 250 kHz. To demonstrate the feasibility of the technique, two experiments are presented: The first experiment compares the measured velocity distribution of a free jet using ILDV performed with the smart pixel detector array and a high-speed camera with a reference measurement using PIV. The second experiment shows an advanced setup using two smart pixel detector arrays to measure the velocity distribution on a rotating disk, demonstrating the potential of the technique for high-velocity flow measurements.

Meier, Alexander H.; Roesgen, Thomas

2012-04-01

49

Photonic doppler velocimetry  

International Nuclear Information System (INIS)

[en] 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

1999-01-01

50

Ultrasonic colour Doppler imaging  

DEFF Research Database (Denmark)

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

Evans, David H.; Jensen, JØrgen Arendt

2011-01-01

51

COLOUR DOPPLER ULTRASOUND  

Directory of Open Access Journals (Sweden)

Full Text Available T he incidence & prevalence of venous thrombosis can only be estimated as most episodes go undetected clinically.Venous Thromboembolism (VTE) is a major source of emboli in 95% cases of pulmonary embolism (P.E), which in tuneris one of the leading causes of death in patients dying undetected. This study was carried out in the Department ofRadiology & Ultrasound at Allied Hospital, PMC Faisalabad for a period of 8 months and total number of cases are100. The objective was to evaluate the case of VTE & their squealae by using Colour Doppler studies. The result was thatcolour doppler sonography and colour enhanced technique has improved the sensitivity of blood flow detection.

SYED MEHDI RAZA RIZVI

2002-01-01

52

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.

53

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

54

Holographic laser Doppler ophthalmoscopy  

CERN Multimedia

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

55

Doppler ultrasound velocity estimation  

UK PubMed Central (United Kingdom)

A spatial-temporal doppler velocity estimation method expands the detectable frequency range by extending the frequency boundary at which aliasing artifacts may occur. In various embodiments the detectable frequency range is extended beyond the Nyquist limit. To do so, multiple velocity estimation functions are defined. One function is the conventional function typically bound by the Nyquist limit. For additional functions, the (n-1)-th echo is spatially shifted with respect to the n-th echo, (i.e., temporal/spatial pulse-pairs are averaged). For example, in one embodiment a shift of + DELTA is inserted to define one additional estimation function, while a shift of - DELTA is inserted to define another additional estimation function. A power function then is calculated for each velocity estimation function. The estimation function having the highest power is selected for use in deriving the doppler shift frequency of a given sample point. By selecting a one of the K+1 velocity estimation functions with the highest power, the detectable frequency range, f, becomes: -(2K/2)fs< f< (2K/2)fs, where fs is the Doppler sampling frequency.

KIM JIN H; LIU DONG-CHYUAN

56

Range Doppler coupling magnifier  

Science.gov (United States)

A pulse expander-compressor for magnifying the range-Doppler-coupling effects that accompany the use of frequency-modulation derived phase coded pulse compressors in order to accentuate the Doppler-coupling velocity effects on target echoes. The foregoing magnification is accomplished by generating a Doppler tolerant polyphase coded waveform with equal time spaces inserted between successive code elements in order to make the time difference between the first and last code elements independent of the number of code elements involved. These equal spaces may be variable in order to allow any desired target radial velocity to produce a phase difference between the first and last code elements of 2 pi. The foregoing may be implemented in a pulse expander-compressor by replacing each delay tc in the compressor input-signal expansion circuit by a set of N delay elements tc, and a set of N associated switches, the switches permitting each element in the set to be connected or bypassed, as desired. The time-dispersion circuit for the compressor is likewise modified by replacing each of its Mtc delays by a set of N delay elements Mtc, each of which is independently connectable or bypassable.

Lewis, B. L.

1986-03-01

57

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

Directory of Open Access Journals (Sweden)

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

DEBORAH H. M. BASTOS; MARIA A. A. P. SILVA; MARIA R. B. FRANCO

2009-01-01

58

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; Mohammad Aghaali

2013-01-01

59

Estudo Doppler na hipertensão portal Doppler evaluation in portal hypertension  

Directory of Open Access Journals (Sweden)

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

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

2004-01-01

60

Clinical applications of doppler ultrasound  

Energy Technology Data Exchange (ETDEWEB)

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

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

1987-01-01

 
 
 
 
61

The effects of different inspired oxygen fractions on gas exchange and Tei-index of myocardial performance in propofol-anesthetized dogs.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To evaluate the influence of different inspired oxygen fractions (FiO2 ) on pulmonary oxygen exchange and Tei-index of myocardial performance in propofol-anesthetized dogs. STUDY DESIGN: Prospective crossover, randomized, experimental trial. ANIMALS: Eight adult dogs weighing 8.6 ± 1.8 kg. METHODS: The animals were anesthetized on five occasions, receiving either an FiO2  = 1.0 (F100), 0.8 (F80), 0.6 (F60), 0.4 (F40) or 0.21 (F21). Propofol was used for induction (6.45 ± 0.69 mgkg(-1) IV) followed by a continuous rate infusion (CRI, 0.7 mgkg(-1)  minute(-1) ). The dogs breathed spontaneously. The initial measurements of arterial partial pressures of oxygen (PaO2 ) and carbon dioxide (PaCO2 ), arterial hemoglobin saturation (SaO2 ), heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), stroke index (SI), pre-ejection period (PEP) and left ventricular ejection time (LVET) were performed 30 minutes after beginning the CRI (T0) and then, at 15-minute intervals (T15-T60). From these measurements the following were calculated; alveolar oxygen partial pressure (PAO2 ), alveolar-arterial oxygen gradient (AaDO2 ), arterial oxygen partial pressure/inspired oxygen fraction ratio (PaO2 /FiO2 ), arterial-to-alveolar oxygen tension ratio (PaO2 /PAO2 ), respiratory index (RI), oxygen delivery (D·O2 ), PEP/LVET ratio, isovolumic relaxation time (IVRT) and Tei-index. RESULTS: At T30, PaCO2 in F100 was higher than in F21. The AaDO2 mean in F100 was greater than in other treatments. PaO2 /FiO2 in F21 was lower than F100 and F80 at T0 and than in F80 and F60 at T15. At T15, PaO2 /PAO2 and RI in F100 were higher than in F80, F60 and F21. At T30, PaO2 /PAO2 in F21 was lower than in F100 and F60. At T30, PEP/LVET in F100 was higher than F80, F40 and F21, which was lower than F80 and F40. CONCLUSION: The Tei-index and cardiovascular parameters are not affected by different FiO2 . CLINICAL RELEVANCE: An FiO2 of 1.0 and 0.21 impaired respiratory efficiency.

Ferro Lopes PC; Nunes N; Sousa MG; Nishimori CT; Carareto R; Dos Santos PS; Camacho AA

2013-08-01

62

Principles of doppler tomography  

International Nuclear Information System (INIS)

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

1992-01-01

63

Estudo Doppler na hipertensão portal  

Directory of Open Access Journals (Sweden)

Full Text Available A ultra-sonografia e o Doppler representaram grande marco no diagnóstico da hipertensão portal. Este fato decorre do aspecto não-invasivo destes métodos, possibilitando o estudo do fígado, do baço e da circulação esplâncnica. Neste artigo os autores discutem alguns aspectos importantes avaliados pela ultra-sonografia e pelo Doppler na avaliação da hipertensão portal.

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

2004-01-01

64

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; Ana Vidaurre; Jaime Riera; Juan A. Monsoriu

2008-01-01

65

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

66

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

UK PubMed Central (United Kingdom)

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.

Fung EK; Planeta-Wilson B; Mulnix T; Carson RE

2009-10-01

67

Doppler characteristics of sea clutter.  

Energy Technology Data Exchange (ETDEWEB)

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

Raynal, Ann Marie; Doerry, Armin Walter

2010-06-01

68

Transversal Doppler-Fizeau effect  

Energy Technology Data Exchange (ETDEWEB)

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

Subacius, E. (Centro Tecnico Aeroespacial, Sao Jose dos Campos (Brazil). Inst. Tecnologico de Aeronautica)

1981-12-01

69

Doppler imaging of HD 184905  

CERN Document Server

A Doppler imaging analysis of HD 184905 is pre-sented. Based on time series of high resolution and high signal-to-noise ratio observations we have refined vsini and v_rad with the help of synthesis modelling tools. The maps of Mg and Si abundance distributions were obtained with the help of Doppler imaging software, which was done for the first time for this particular object.

Makaganiuk, V A

2011-01-01

70

Adaptive Spectral Doppler Estimation  

DEFF Research Database (Denmark)

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

Gran, Fredrik; Jakobsson, Andreas

2009-01-01

71

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

Science.gov (United States)

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

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

2013-02-01

72

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

International Nuclear Information System (INIS)

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

2011-01-01

73

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

Energy Technology Data Exchange (ETDEWEB)

There is growing interest in monitoring response to therapy in oncology patients using positron emission tomography and fluorine-18 fluorodeoxyglucose (FDG). Quantification is required, and various methods have been described. Arterial sampling, which provides the most accurate input function, often is not feasible in patients undergoing chemotherapy. In the thorax an image-derived input function can be obtained from the large vascular structures. In many studies the left ventricle (LV) is used, but the obtained data are rarely validated. In this study a simple quality control procedure for the image-derived input function was developed and compared with a standard LV curve. Twenty dynamic FDG scans were obtained in nine patients with non-small cell lung cancer stage IIIA-N2. Three venous blood samples were taken as a quality control for the image-derived input function. Regions of interest (ROIs) were defined for aorta, LV and left atrium. Input curves were generated according the the standard use of the LV curve and by applying the quality control method to all vascular ROIs. Tumour ROIs were defined and both input functions were used to calculate tumour glucose metabolism (MRglu), using both standard non-linear regression and Patlak analyses. Mean differences in MRglu using ''standard'' LV and ''quality control approved'' input functions were 16.2% and 17.5% for non-linear regression and Patlak analyses, respectively, iondicating that the use of ''standard'' LV 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.)

Hoekstra, C.J. [Dept. of Pulmonary Medicine, University Hospital Vrije Universiteit, Amsterdam (Netherlands); Clinical PET Centre, University Hospital Vrije Universiteit, Amsterdam (Netherlands); Hoekstra, O.S. [Clinical PET Centre, University Hospital Vrije Universiteit, Amsterdam (Netherlands); Department of Clinical Epidemiology, University Hospital Vrije Universiteit, Amsterdam (Netherlands); Lammertsma, A.A. [Clinical PET Centre, University Hospital Vrije Universiteit, Amsterdam (Netherlands)

1999-11-01

74

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

Directory of Open Access Journals (Sweden)

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

Bohdan Firek; Jacek Wo?niak; Alicja Kraska; Wanda Szyma?ska-Jagie??o; Ilona Kowalik; Hanna Szwed

2004-01-01

75

Duplex/doppler ultrasound test (image)  

Science.gov (United States)

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

76

Color Doppler Ultrasound Indices in Endometriotic Cysts  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. <...

Parisa Hajialioghlo; Fatemeh Ghatresamani; Nariman Nezami; Narges Sobhani

77

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.

1990-01-01

78

Human rights – local value or universal norm? Žmogaus teis?s – lokalin?s vertyb?s ar visuotin?s normos?  

Directory of Open Access Journals (Sweden)

Full Text Available The article argues for the universal character of human rights. It is demonstrated that they are not of specific value of Western culture but are a universal norm. This norm is valid not only for political practices but, first of all, for the morality and practice of argumentation. Human rights are strictly correlated with Kantian Categorical Imperative and can be substantiated by means of transcendental­pragmatic argument (K.­O. Apel). The difference between values and norms are also considered. It is demonstrated that values are always subjective and arbitrary meanwhile final justification is possible for norms.  Article in RussianGrindžiamas visuotinis žmogaus teisi? pob?dis, argumentuojama, kad jos n?ra nuoseklios Vakar? kult?ros vertyb?s, bet veikiau turi b?ti traktuojamos kaip universalios normos. Šios normos galioja ne tik politin?je praktikoje, bet pirmiausia moral?s srityje ir argumentavimo praktikoje. Straipsnyje pabr?žiama, kad žmogaus teis?s yra glaudžiai susijusios su Kanto kategoriniu imperatyvu ir gali b?ti pateisintos pasitelkus transcendental?-pragmatin? argument? (K. O. Apelis). Straipsnyje taip pat nagrin?jami skirtumai tarp vertybi? ir norm?, grindžiama mintis, kad vertyb?s visuomet yra subjektyvios ir sutartin?s, o normos gali tur?ti finalin? pagrindim?. Straipsnis rus? kalba

Grigory Gutner

2009-01-01

79

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

2010-01-01

80

Anomalous Doppler effects in bulk phononic crystal  

International Nuclear Information System (INIS)

[en] Doppler effects in simple cubic phononic crystal are studied theoretically and numerically. In addition to observing Doppler shifts from a moving source's frequencies inside the gap, we find that Doppler shifts can be multi-order, anisotropic, and the dominant order of shift depends on the band index that the source's frequency is in.

2010-08-23

 
 
 
 
81

Anomalous Doppler effects in bulk phononic crystal  

Energy Technology Data Exchange (ETDEWEB)

Doppler effects in simple cubic phononic crystal are studied theoretically and numerically. In addition to observing Doppler shifts from a moving source's frequencies inside the gap, we find that Doppler shifts can be multi-order, anisotropic, and the dominant order of shift depends on the band index that the source's frequency is in.

Cai Feiyan [Key Lab of Acoustic and Photonic Materials and Devices of Ministry of Education and Department of Physics, Wuhan University, Wuhan 430072 (China); Paul. C. Lauterbur Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Key Laboratory of Biomedical Informatics and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); He Zhaojian; Zhang Anqi; Ding Yiqun [Key Lab of Acoustic and Photonic Materials and Devices of Ministry of Education and Department of Physics, Wuhan University, Wuhan 430072 (China); Liu Zhengyou, E-mail: zyliu@whu.edu.c [Key Lab of Acoustic and Photonic Materials and Devices of Ministry of Education and Department of Physics, Wuhan University, Wuhan 430072 (China)

2010-08-23

82

Role of transcranial Doppler ultrasonography in stroke  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transcranial Doppler sonongraphy is a non?invasive, non?ionising, inexpensive, portable and safe technique that uses a pulsed Doppler transducer for assessment of intracerebral blood flow. This article deals with the principles and technique of transcranial Doppler sonography. It gives a brief overv...

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

83

Position of first Doppler peak  

Energy Technology Data Exchange (ETDEWEB)

A analytic derivation is made of the position of the first Doppler peak for the cosmic background radiation anisotropy. The resulting depndences on {Omega}{sub m} and {Omega}{sub {Lambda}} agree well with numerical results showing that the principal physics is the geometry of the geodesics since last scatter at recombination time. {copyright} {ital 1999 American Institute of Physics.}

Frampton, P.H. [University of North Carolina, Chapel Hill, North Carolina 27599-3255 (United States)

1999-07-01

84

Computer Analysis of Doppler Signals  

Directory of Open Access Journals (Sweden)

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

DR?GHICIU Nicolae; POPA Sorin

2011-01-01

85

Space-Borne Coherent Doppler Lidar  

Science.gov (United States)

Global wind profiling with a space-borne Doppler lidar is expected to bring big progress in the studies on global climate modeling and accurate numerical weather prediction. This research program aims at a demonstration of the coherent Doppler lidar technology in space. CRL has been conducting feasibility study on the coherent Doppler lidar aiming at demonstration onboard the Japanese Experiment module of the International Space Station. We are in parallel developing an airborne coherent Doppler lidar system to measure wind profile under a jet plane for simulation of the Doppler lidar measurement in space. This system is also operated in the ground to develop algorithm of the wind measurements.

Mizutani, Kohei; Itabe, Toshikazu; Ishii, Shoken; Sasano, Masahiko; Aoki, Tetsuo; Ohno, Yuichi; Asai, Kazuhiro

2002-06-01

86

Doppler indicates of uterine artery Doppler velocimetry by placental location  

International Nuclear Information System (INIS)

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

2001-01-01

87

Doppler indicates of uterine artery Doppler velocimetry by placental location  

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-09-15

88

Doppler velocimetry in prolonged pregnancy.  

UK PubMed Central (United Kingdom)

Eighty-two patients at 287 days' gestation or longer were tested by nonstress test (NST), amnioscopy, ultrasound assessment of amniotic fluid volume, and Doppler velocimetry. Several maternal and fetal arteries were analyzed: uterine, umbilical, descending thoracic aorta, renal, and middle cerebral. During the study, other maternal-fetal functional indices were recorded: hPL, estriol, hematocrit, platelets, mean platelet volume, and uric acid. No abnormalities were found in the uterine, umbilical, middle cerebral, thoracic descending aorta, and renal artery velocimetry in post-dates gestations. However, a significant reduction of the time-averaged mean velocity in the descending thoracic aorta was associated with an increased incidence of oligohydramnios, meconium-stained fluid, abnormal NST, and cesarean delivery for fetal distress. The present study suggests that serial Doppler flow measurements of mean velocity of the fetal descending thoracic aorta may be a simple and rapid technique for identifying prolonged pregnancies at increased risk for perinatal complications.

Battaglia C; Larocca E; Lanzani A; Coukos G; Genazzani AR

1991-02-01

89

Moments of ambient Doppler spectra  

Energy Technology Data Exchange (ETDEWEB)

The author studied the first four moments (center of mass, standard deviation, skew, and kurtosis) of the Doppler spectra in ambient regions of LLNL-Hughes real aperture radar data collected during WCSEX91--92. The goal was to correlate trends in the moments with wind velocity and direction. Although the center of mass appears to increase when the wind is blowing into the radar antenna, no other conclusions have been drawn from the higher order moments.

Lehman, S.K.

1993-03-23

90

Doppler Signal Processing and Instrumentation for Modified 'Porcupine' C-Band Pulse Doppler Radar.  

Science.gov (United States)

Section 1 of the report summarizes doppler signal processing techniques in the following areas: Fast fourier transform processing; 'Pulse pair' processing; Doppler separation using a hilbert transformer. Section 2 of the report summarizes the following in...

F. E. Compton H. L. Groginsky R. B. Campbell V. Friedmann

1971-01-01

91

Avaliação dos tumores hepáticos ao Doppler Doppler evaluation of liver tumors  

Directory of Open Access Journals (Sweden)

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

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

2004-01-01

92

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

Directory of Open Access Journals (Sweden)

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

K. A. JALES; G. A. MAIA; D. S. GARRUTI; M. A. SOUZA NETO; H. M. C. AZEREDO; E. S. BRITO

2009-01-01

93

Frequency domain phase-resolved optical Doppler and Doppler variance tomography  

Science.gov (United States)

Frequency domain phase-resolved optical Doppler tomography (ODT) was developed with Doppler variance imaging capability. It is shown that utilizing the frequency domain method, phase-resolved ODT can achieve much higher imaging speed and velocity dynamic range than the time domain method. Structural, Doppler and Doppler variance images of fluid flow through glass channels were quantified and blood flow through vessels were demonstrated in vivo.

Wang, Lei; Wang, Yimin; Guo, Shuguang; Zhang, Jun; Bachman, Mark; Li, G. P.; Chen, Zhongping

2004-12-01

94

Doppler color imaging. Principles and instrumentation.  

Science.gov (United States)

DCI acquires Doppler-shifted echoes from a cross-section of tissue scanned by an ultrasound beam. These echoes are then presented in color and superimposed on the gray-scale anatomic image of non-Doppler-shifted echoes received during the scan. The flow echoes are assigned colors according to the color map chosen. Usually red, yellow, or white indicates positive Doppler shifts (approaching flow) and blue, cyan, or white indicates negative shifts (receding flow). Green is added to indicate variance (disturbed or turbulent flow). Several pulses (the number is called the ensemble length) are needed to generate a color scan line. Linear, convex, phased, and annular arrays are used to acquire the gray-scale and color-flow information. Doppler color-flow instruments are pulsed-Doppler instruments and are subject to the same limitations, such as Doppler angle dependence and aliasing, as other Doppler instruments. Color controls include gain, TGC, map selection, variance on/off, persistence, ensemble length, color/gray priority. Nyquist limit (PRF), baseline shift, wall filter, and color window angle, location, and size. Doppler color-flow instruments generally have output intensities intermediate between those of gray-scale imaging and pulsed-Doppler duplex instruments. Although there is no known risk with the use of color-flow instruments, prudent practice dictates that they be used for medical indications and with the minimum exposure time and instrument output required to obtain the needed diagnostic information. PMID:1497942

Kremkau, F W

1992-01-01

95

Doppler color imaging. Principles and instrumentation.  

UK PubMed Central (United Kingdom)

DCI acquires Doppler-shifted echoes from a cross-section of tissue scanned by an ultrasound beam. These echoes are then presented in color and superimposed on the gray-scale anatomic image of non-Doppler-shifted echoes received during the scan. The flow echoes are assigned colors according to the color map chosen. Usually red, yellow, or white indicates positive Doppler shifts (approaching flow) and blue, cyan, or white indicates negative shifts (receding flow). Green is added to indicate variance (disturbed or turbulent flow). Several pulses (the number is called the ensemble length) are needed to generate a color scan line. Linear, convex, phased, and annular arrays are used to acquire the gray-scale and color-flow information. Doppler color-flow instruments are pulsed-Doppler instruments and are subject to the same limitations, such as Doppler angle dependence and aliasing, as other Doppler instruments. Color controls include gain, TGC, map selection, variance on/off, persistence, ensemble length, color/gray priority. Nyquist limit (PRF), baseline shift, wall filter, and color window angle, location, and size. Doppler color-flow instruments generally have output intensities intermediate between those of gray-scale imaging and pulsed-Doppler duplex instruments. Although there is no known risk with the use of color-flow instruments, prudent practice dictates that they be used for medical indications and with the minimum exposure time and instrument output required to obtain the needed diagnostic information.

Kremkau FW

1992-01-01

96

Application of image-derived and venous input functions in major depression using [carbonyl-(11)C]WAY-100635.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Image-derived input functions (IDIFs) represent a promising non-invasive alternative to arterial blood sampling for quantification in positron emission tomography (PET) studies. However, routine applications in patients and longitudinal designs are largely missing despite widespread attempts in healthy subjects. The aim of this study was to apply a previously validated approach to a clinical sample of patients with major depressive disorder (MDD) before and after electroconvulsive therapy (ECT). METHODS: Eleven scans from 5 patients with venous blood sampling were obtained with the radioligand [carbonyl-(11)C]WAY-100635 at baseline, before and after 11.0±1.2 ECT sessions. IDIFs were defined by two different image reconstruction algorithms 1) OSEM with subsequent partial volume correction (OSEM+PVC) and 2) reconstruction based modelling of the point spread function (TrueX). Serotonin-1A receptor (5-HT1A) binding potentials (BPP, BPND) were quantified with a two-tissue compartment (2TCM) and reference region model (MRTM2). RESULTS: Compared to MRTM2, good agreement in 5-HT1A BPND was found when using input functions from OSEM+PVC (R(2)=0.82) but not TrueX (R(2)=0.57, p<0.001), which is further reflected by lower IDIF peaks for TrueX (p<0.001). Following ECT, decreased 5-HT1A BPND and BPP were found with the 2TCM using OSEM+PVC (23%-35%), except for one patient showing only subtle changes. In contrast, MRTM2 and IDIFs from TrueX gave unstable results for this patient, most probably due to a 2.4-fold underestimation of non-specific binding. CONCLUSIONS: Using image-derived and venous input functions defined by OSEM with subsequent PVC we confirm previously reported decreases in 5-HT1A binding in MDD patients after ECT. In contrast to reference region modeling, quantification with image-derived input functions showed consistent results in a clinical setting due to accurate modeling of non-specific binding with OSEM+PVC.

Hahn A; Nics L; Baldinger P; Wadsak W; Savli M; Kraus C; Birkfellner W; Ungersboeck J; Haeusler D; Mitterhauser M; Karanikas G; Kasper S; Frey R; Lanzenberger R

2013-04-01

97

Doppler Imaging of Ap Stars  

CERN Multimedia

Doppler imaging, a technique which inverts spectral line profile variations of an Ap star into a two-dimensional abundance maps, provides new observational constraints on diffusion mechanism in the presence of a global magnetic field. A programme is presented here with the aim to obtain abundance distributions of at least five elements on each star, in order to study how different diffusion processes act under influence of a stellar magnetic field. The importance of this multi-element approach is demonstrated, by presenting the abundance maps of helium, magnesium, silicon, chromium and iron for the magnetic B9pSi star CU Virginis.

Kuschnig, R

1998-01-01

98

Doppler echocardiographic evaluation of valve regurgitation in healthy volunteers.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVE--To study the prevalence and the characteristics of physiological valve regurgitation. DESIGN--Pulsed wave Doppler echocardiography, continuous wave Doppler echocardiography and Doppler colour flow mapping were performed prospectively in healthy volunteers. SETTING--Echocardiography labora...

Jobic, Y; Slama, M; Tribouilloy, C; Lan Cheong Wah, L; Choquet, D; Boschat, J; Penther, P; Lesbre, J P

99

Renal duplex Doppler ultrasound findings in diabetics  

International Nuclear Information System (INIS)

The correlation between clinical-laboratory findings and renal duplex Doppler ultrasound findings was studied in 45 patients with diabetes mellitus to see the role of duplex Doppler ultrasound in the detection of diabetic nephropathy. The resistive indices in patients with elevated serum creatinine, BUN, proteinuria, and systolic blood pressure levels were statistically significantly higher than those in patients with normal levels (p

1993-01-01

100

Signal validation in laser-Doppler velocimetry  

International Nuclear Information System (INIS)

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

1988-01-01

 
 
 
 
101

Doppler study of precordial musical murmurs.  

Science.gov (United States)

Using phonocardiography, continuous- and pulsed-wave Doppler, 51 patients with precordial "musical" murmurs (49 with cardiac abnormalities) and 21 patients with noisy murmurs were examined. With M-mode echocardiography, fine fluttering of the structure generating the murmur was evident in 23 patients with musical murmurs and in 5 with noisy murmurs. A continuous-wave Doppler spectral signal characterized by parallel harmonics (Doppler musical signal) was evident in all patients with musical murmurs and in none with a noisy murmur. With pulsed-wave Doppler, the musical signal had less defined spectral features because of range ambiguity. Such a signal was experimentally reproduced by activating a diapason bathed in saline solution. The source of the musical murmur was established in all 51 patients by Doppler. The musical signal was associated with a valvular regurgitation signal in 36 patients and with a ventricular septal defect in 1 patient. The musical signal always disappeared when the pulsed-wave Doppler sample volume was placed 2 cm away from the generating structure. In 11 patients with musical murmur examined by color Doppler, no abnormal bidirectional flow signal was observed in the structures generating the signal. In 6 of the patients without valvular regurgitation, no flow disturbance was found. In conclusion, Doppler is valuable in determining the source of musical murmurs, and musical murmurs are caused by a vibrating structure even in the absence of flow turbulence. PMID:2729112

Pennestri, F; Boccardi, L; Minardi, G; Di Segni, M; Pucci, E; Biasucci, L M; Ferrari, O; Lombardo, A; Giovannini, E; Loperfido, F

1989-06-01

102

Doppler study of precordial musical murmurs.  

UK PubMed Central (United Kingdom)

Using phonocardiography, continuous- and pulsed-wave Doppler, 51 patients with precordial "musical" murmurs (49 with cardiac abnormalities) and 21 patients with noisy murmurs were examined. With M-mode echocardiography, fine fluttering of the structure generating the murmur was evident in 23 patients with musical murmurs and in 5 with noisy murmurs. A continuous-wave Doppler spectral signal characterized by parallel harmonics (Doppler musical signal) was evident in all patients with musical murmurs and in none with a noisy murmur. With pulsed-wave Doppler, the musical signal had less defined spectral features because of range ambiguity. Such a signal was experimentally reproduced by activating a diapason bathed in saline solution. The source of the musical murmur was established in all 51 patients by Doppler. The musical signal was associated with a valvular regurgitation signal in 36 patients and with a ventricular septal defect in 1 patient. The musical signal always disappeared when the pulsed-wave Doppler sample volume was placed 2 cm away from the generating structure. In 11 patients with musical murmur examined by color Doppler, no abnormal bidirectional flow signal was observed in the structures generating the signal. In 6 of the patients without valvular regurgitation, no flow disturbance was found. In conclusion, Doppler is valuable in determining the source of musical murmurs, and musical murmurs are caused by a vibrating structure even in the absence of flow turbulence.

Pennestri F; Boccardi L; Minardi G; Di Segni M; Pucci E; Biasucci LM; Ferrari O; Lombardo A; Giovannini E; Loperfido F

1989-06-01

103

Differential Doppler traking of interplanetary spacecraft  

International Nuclear Information System (INIS)

Simultaneous Doppler traking of the same spacecraft from two widely separated stations on the ground can be profitably used in space experiments for the detection of low-frequency gravitational waves. The second, reciving only station, could be a VLBI radiotelescope. The instrumentation required to convert a VLBI system to Doppler measurement is relatively easy to set up and uses a digital tone extractor.

1987-01-01

104

Doppler Resilient Waveforms with Perfect Autocorrelation  

CERN Multimedia

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

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

2007-01-01

105

Doppler transcraniano na prática neurológica  

Directory of Open Access Journals (Sweden)

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

Zétola Viviane Flumignan; Lange Marcos Christiano; Muzzio Juliano A.; Marchioro Ivo; Nóvak Edison Mattos; Werneck Lineu C.

2006-01-01

106

Color doppler ultrasonography diagnosis of intramuscular hemangioma  

International Nuclear Information System (INIS)

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

2008-01-01

107

Endarterectomía carotídea: monitoreo intraoperatorio con Doppler transcraneano  

Directory of Open Access Journals (Sweden)

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

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

2007-01-01

108

Endarterectomía carotídea: monitoreo intraoperatorio con Doppler transcraneano  

Scientific Electronic Library Online (English)

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

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

2007-09-01

109

Novel nonlinear adaptive Doppler shift estimation technique (NADSET) for the coherent Doppler lidar system VALIDAR  

Science.gov (United States)

A novel Nonlinear Adaptive Doppler Shift Estimation Technique (NADSET) is introduced in this paper. The quality of Doppler shift and power estimations by conventional Fourier-transform-based spectrum estimation methods deteriorates rapidly in low signal-to-noise-ratio (SNR) environment. The new NADSET algorithm compensates such deterioration in the quality of wind parameter estimates by adaptively utilizing the statistics of Doppler shift estimate in strong SNR ranges and identifying sporadic range bins where good Doppler shift estimates are found. NADSET is based on the nature of continuous wind profile and significantly improves the accuracy and the quality of Doppler shift estimates in low SNR ranges. The authenticity of NADSET is established by comparing the trend of wind parameters with and without NADSET applied to the lidar returns acquired over a long period of time by the coherent Doppler lidar system VALIDAR at NASA Langley Research Center in Virginia.

Beyon, Jeffrey Y.; Koch, Grady J.

2006-06-01

110

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Although Doppler colour flow mapping may considerably reduce the need for conventional pulsed Doppler examination, quantitative flow measurements (particularly by continuous wave Doppler) are still essential in the evaluation of many conditions such as aortic stenosis. Doppler colour flow mapping is...

Monaghan, M J; Mills, P

111

The Doppler principle and the study of cardiac flows  

International Nuclear Information System (INIS)

[en] Doppler instruments allow us to use the Doppler principle to study normal and abnormal blood flows through the heart. To perform or interpret cardiac Doppler examinations, it is necessary to understand the basics of blood flow and some basics of Doppler physics. The authors' purpose in this chapter is to present the elementary principles and avoid complex and detailed discussions

1986-01-01

112

Nonorthogonal Measurement Axes in Laser Doppler Velocimetry.  

Science.gov (United States)

The measurement axes of virtually all multiaxis laser Doppler velocimeter (LDV) systems are nonorthogonal to some degree and are, in general, rotated with respect to orthogonal, Cartesian reference axes. Systematic errors are introduced into the LDV data ...

F. L. Crosswy

1979-01-01

113

Doppler coefficient measurements in Zebra Core 5  

International Nuclear Information System (INIS)

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

1965-01-01

114

Doppler Effect of Mechanical Waves and Light  

Directory of Open Access Journals (Sweden)

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

Lianxi Ma; Junjun Yang; Jiacai Nie

2009-01-01

115

Holographic Doppler imaging of rotating objects.  

UK PubMed Central (United Kingdom)

The Doppler frequency shift of coherent light reflected from rotating objects is used to obtain one-dimensional resolution much greater than the classical limit for aperture limited imaging systems. The Doppler information is processed by using the temporal and spatial filtering properties of modulated-referencewave holograms. The holographic reconstruction is a superresolved image. Resolution improvements greater than 200 times the classical limit were obtained at good signal-to-noise ratios.

Aleksoff CC; Christensen CR

1975-01-01

116

Color Doppler Ultrasound Indices in Endometriotic Cysts  

Directory of Open Access Journals (Sweden)

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

Parisa Hajialioghlo; Fatemeh Ghatresamani; Nariman Nezami; Narges Sobhani

2009-01-01

117

Velocity measurement by vibro-acoustic Doppler.  

UK PubMed Central (United Kingdom)

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

Nabavizadeh A; Urban MW; Kinnick RR; Fatemi M

2012-04-01

118

Advances in transcranial Doppler US: imaging ahead.  

UK PubMed Central (United Kingdom)

Transcranial Doppler ultrasonography (US) is a noninvasive, portable technique for evaluating the intracranial vasculature. It has found its most useful clinical application in the detection of vasospasm involving the cerebral vessels after subarachnoid hemorrhage due to aneurysm rupture. The technique has become an integral part of monitoring and managing patients with subarachnoid hemorrhage in the neurologic intensive care unit. In addition, it has proved useful for evaluating the intracranial vasculature in patients with sickle cell disease, stroke, or brain death. Transcranial US originated as a "blind" nonimaging study in which pulsed Doppler technology was used. Identification of the major intracranial vessels and evaluation of those vessels for vasospasm relied on spectral waveforms obtained in each vessel and was based on the depth of the vessel from the skull, the direction of blood flow, and the orientation of the transducer. Recent advances in US technology allow the use of gray-scale, spectral Doppler, and color Doppler flow imaging to directly visualize intracranial vessels, thereby simplifying flow velocity measurements and enhancing their accuracy for vasospasm detection. In particular, measurements of peak systolic velocity and mean flow velocity and calculation of the Lindegaard ratio facilitate the identification of vessels that may be in vasospasm and help differentiate vasospasm from physiologic conditions such as hyperemia and autoregulation. Thus, gray-scale and color Doppler flow imaging offer many advantages over the original pulsed Doppler technique for evaluating the intracranial vasculature.

Kirsch JD; Mathur M; Johnson MH; Gowthaman G; Scoutt LM

2013-01-01

119

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

120

Doppler evaluation of valvular regurgitation  

International Nuclear Information System (INIS)

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

1986-01-01

 
 
 
 
121

Usefulness of tissue Doppler imaging to predict arrhythmic events in adults with repaired tetralogy of Fallot.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Adults with repaired tetralogy of Fallot (TOF) may be at risk for progressive right ventricular (RV) dilatation and dysfunction, which is commonly associated with arrhythmic events. In frequently volume-overloaded patients with congenital heart disease, tissue Doppler imaging (TDI) is particularly useful for assessing RV function. However, it is not known whether RV TDI can predict outcome in this population. OBJECTIVE: To evaluate whether RV TDI parameters are associated with supraventricular arrhythmic events in adults with repaired TOF. METHODS: We studied 40 consecutive patients with repaired TOF (mean age 35 +/- 11 years, 62% male) referred for routine echocardiographic exam between 2007 and 2008. The following echocardiographic measurements were obtained: left ventricular (LV) ejection fraction, LV end-systolic volume, LV end-diastolic volume, RV fractional area change, RV end-systolic area, RV end-diastolic area, left and right atrial volumes, mitral E and A velocities, RV myocardial performance index (Tei index), tricuspid annular plane systolic excursion (TAPSE), myocardial isovolumic acceleration (IVA), pulmonary regurgitation color flow area, TDI basal lateral, septal and RV lateral peak diastolic and systolic annular velocities (E' 1, A' 1, S' 1, E' s, A' s, S' s, E' rv, A' rv, S' rv), strain, strain rate and tissue tracking of the same segments. QRS duration on resting ECG, total duration of Bruce treadmill exercise stress test and presence of exercise-induced arrhythmias were also analyzed. The patients were subsequently divided into two groups: Group 1--12 patients with previous documented supraventricular arrhythmias (atrial tachycardia, fibrillation or flutter) and Group 2 (control group)--28 patients with no previous arrhythmic events. Univariate and multivariate analysis was used to assess the statistical association between the studied parameters and arrhythmic events. RESULTS: Patients with previous events were older (41 +/- 14 vs. 31 +/- 6 years, p = 0.005), had wider QRS (173 +/- 20 vs. 140 +/- 32 ms, p = 0.01) and lower maximum heart rate on treadmill stress testing (69 +/- 35 vs. 92 +/- 9%, p = 0.03). All patients were in NYHA class I or II. Clinical characteristics including age at corrective surgery, previous palliative surgery and residual defects did not differ significantly between the two groups. Left and right cardiac chamber dimensions and ventricular and valvular function as evaluated by conventional Doppler parameters were also not significantly different. Right ventricular strain and strain rate were similar between the groups. However, right ventricular myocardial TDI systolic (Sa: 5.4+2 vs. 8.5 +/- 3, p = 0.004) and diastolic indices and velocities (Ea, Aa, septal E/Ea, and RV free wall tissue tracking) were significantly reduced in patients with arrhythmias compared to the control group. Multivariate linear regression analysis identified RV early diastolic velocity as the sole variable independently associated with arrhythmic history (RV Ea: 4.5 +/- 1 vs. 6.7 +/- 2 cm/s, p = 0.01). A cut-off for RV Ea of < 6.1 cm/s identified patients in the arrhythmic group with 86% sensitivity and 59% specificity (AUC = 0.8). CONCLUSIONS: Our results suggest that TDI may detect RV dysfunction in patients with apparently normal function as assessed by conventional echocardiographic parameters. Reduction in RV early diastolic velocity appears to be an early abnormality and is associated with occurrence of arrhythmic events. TDI may be useful in risk stratification of patients with repaired tetralogy of Fallot.

Ramos R; Branco L; Agapito A; Oliveira JA; Sousa L; Galrinho A; Fiarresga A; Toste A; Lousinha A; Oliveira M; Da Silva JN; Ferreira RC

2010-07-01

122

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; Xinhong Wang; Yi Zhou; Ping Wang; Fuqiang Liu

2012-01-01

123

Doppler radar imaging of spherical planetary surfaces  

International Nuclear Information System (INIS)

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

1990-01-01

124

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; Till Viktor; Hadna?ev Dušan; Govor?in Mira; Lu?i? Zorka; Lovrenski Jovan

2007-01-01

125

Positron Doppler Broadening of Pure Elemental Metals  

Science.gov (United States)

Positron Doppler Broadening experiments using either a Sodium 22 or a Germanium 68 source were run on a range of pure elemental metals. The results are presented as ratios of the 511 keV annihilation line spectra to selected standard metals as a function of momentum of the atomic electron. The data are compared with theoretical calculations and with previous experimental results using the Coincidence Doppler Broadening method. Additionally, systematic investigations were done to determine the best techniques for optimization of the data. The factors that have an effect on the data include counting rate, detector resolution, amplifier shaping time, source backing material, background and total number of counts in the 511 keV annihilation peak. Furthermore, we were able to extend our results using the Germanium 68 source to a quality close to that of the more expensive and complex Coincidence Doppler Broadening practice.

Fernandez, Desmond; Quarles, C. A.

2011-10-01

126

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=0.001)and end-diastolic velocity(6.83±1.91 vs 13.99±4.15, P=0.001)for ophthalmic artery in amblyopic eyes.CONCLUSION: Our study showed amblyopic eyes may present a decrease in retrobulbar blood flow velocity.

Ece Turan-Vural; Handan Ucankale; Alev Kahya

2013-01-01

127

Doppler effect in Schwarzschild and Kerr geometries  

International Nuclear Information System (INIS)

[en] Calculation of the Doppler shift in general relativity involves contributions of gravitational and kinematical origins and for most metrics or trajectories these contributions are coupled. The exact expression for this Doppler shift may simplify for particular symmetries. Here the specific case for a light signal emitted by a distant inertial observer and received by an in-falling observer in a Schwarzschild geometry is discussed. The resulting expression the Doppler shift is composed of simple factors that can be clearly identified with contributions arising from classical kinematical, special relativistic and general relativistic origins. This result turns out to be more general and it holds for a case of an arbitrary radial in-fall in Schwarzschild geometry and for a particular type of in-fall in the case of a Kerr metric

2008-03-01

128

Research on the Laser Doppler Torque Sensor  

International Nuclear Information System (INIS)

Based on laser Doppler effect, single section rotational speed of a rotating shaft was measured. By measuring the two sections rotational speed, the difference of the rotational speed between the two could be made. Integrating the rotational speed difference, the relative torsional angle of the two sections under the action of torsional virbration was received, so the rotating shaft torque was gotten. Non-contact torque measurement of rotary machine was achieved. The system was designed and the experiment was done on the torque experiment equipment. The result of experimentation indicate that the relative error between Laser Doppler and conventional torque measuring method that was less than 0.2%, and the measurement accuracy of Laser Doppler was high.

2006-01-01

129

Inline Ultrasonic Rheometry by Pulsed Doppler  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-12-22

130

Inline ultrasonic rheometry by pulsed Doppler.  

Science.gov (United States)

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

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

2006-06-02

131

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

132

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

1996-01-01

133

Doppler flow patterns in pediatric pulmonary pathology  

International Nuclear Information System (INIS)

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

1996-01-01

134

Rotational Doppler beaming in eclipsing binaries  

CERN Multimedia

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

Groot, Paul J

2011-01-01

135

The parametric Doppler effect in quartz glass  

Science.gov (United States)

Transformation of frequency is analyzed under the parametric Doppler effect in quartz glass in the "optic collider" scheme. In this scheme, intense laser radiation induces moving inhomogeneities of the refractive index in the glass and the probe radiation undergoes the Doppler frequency shift when being reflected from them. The possibilities of transforming the frequency both within the main transparent region and from the main transparent region to the low- and high-frequency regions separated from the main region by absorption peaks in the infrared and ultraviolet spectral ranges are demonstrated.

Vysotina, N. V.; Rosanov, N. N.; Alekseev, S. G.; Ermolaeva, G. M.; Shilov, V. B.; Malevich, V. L.; Sinitsyn, G. V.

2013-08-01

136

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.

2007-01-01

137

Sub-Doppler Raman saturation spectroscopy.  

Science.gov (United States)

Sub-Doppler linewidth spectra of the Q(01) (2) transition in deuterium (D(2)) have been obtained by using a stimulated Raman technique analogous to sub-Doppler IR saturation spectroscopy. Two experimental configurations are described that employ alternatively either three or four laser beams at two frequencies. The saturation dip is detected by using an inverse Raman technique to probe the saturated line shape. It is shown that, by delaying the pulsed measurement from the pulsed saturation, the technique can be used to study velocity relaxation processes in homonuclear diatomics or other Raman-active molecules. PMID:19693249

Owyoung, A; Esherick, P

1980-10-01

138

Proposed protocols for peripheral and renal Doppler  

International Nuclear Information System (INIS)

A literature review was performed in order to prepare a summary of the important concepts of Doppler and applications in peripheral vascular evaluation and renal. The normal characteristics are summarized and explained in each vascular system and diagnostic criteria of the disorders frequently encountered in practice. Requested more studies have been identified and proposed protocols and report sheets have been developed to standardize the methodology of realization of several Doppler studies. The variability between operators has been treated to reduce as much as possible and follow-up studies have provided in patients who need. (author)

2009-01-01

139

Laser Doppler Velocimeter particle velocity measurement system  

Energy Technology Data Exchange (ETDEWEB)

This report gives a detailed description of the operation of the Laser Doppler Velocimeter (LDV) system maintained by DIAL at MSU. LDV is used for the measurement of flow velocities and turbulence levels in various fluid flow settings. Ills report details the operation and maintenance of the LDV system and provides a first-time user with pertinent information regarding the system`s setup for a particular application. Particular attention has been given to the use of the Doppler signal analyzer (DSA) and the burst spectrum analyzer (BSA) signal processors and data analysis.

Wilson, W.W.; Srikantaiah, D.V.; Philip, T.; George, A.

1993-10-01

140

Signal-to-noise improvement in laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

Simple optical methods are described that, working in conjunction with an electronic synchronous detector, can substantially increase signal detectability in laser Doppler velocimetry. These methods involve rotating the laser polarization to amplitude-modulate exclusively the Doppler signal.

Le-Cong P; Lovberg RH

1980-12-01

 
 
 
 
141

Performance Analysis of a Multistatic Coherent Doppler Lidar.  

Science.gov (United States)

Wind velocity can be obtained using a light detection and ranging (lidar) system by measuring the Doppler shift of the scattered return from aerosols and particulates in the atmosphere. Doppler lidar systems for wind velocity measurements can be classifie...

E. P. Magee

1999-01-01

142

Transcranial Doppler and angiographic findings in adolescent stretch syncope.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The clinical, angiographic, and Doppler findings are reported for two young patients with recurrent syncope induced by neck hyperextension during stretching. Transcranial Doppler monitoring of both posterior cerebral arteries was performed during head manoeuvres. There were reproducible rapid decrea...

Sturzenegger, M; Newell, D W; Douville, C M; Byrd, S; Schoonover, K D; Nicholls, S C

143

A comparison of Doppler optical coherence tomography methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract: We compare, in detail, the phase-resolved color Doppler (PRCD), phase-resolved Doppler variance (PRDV) and intensity-based Doppler variance (IBDV) methods. All the methods are able to quantify flow speed when the flow rate is within a certain range, which is dependent on the adjacent A-lin...

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

144

Measurement depth and volume in laser Doppler flowmetry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new method for estimating the measurement depth and volume in laser Doppler flowmetry (LDF) is presented. The method is based on Monte Carlo simulations of light propagation in tissue. The contribution from each individual Doppler shift is calculated and thereby multiple Doppler shifts are handled...

Fredriksson, Ingemar; Larsson, Marcus; Strömberg, Tomas

145

Detection des Pertes de Connaissance en Vol Par Methode Doppler (Detection of Loss of Consciousness in Flight by Doppler Method).  

Science.gov (United States)

The use of transcranial Doppler monitoring is recommended for detecting acceleration induced loss of consciousness (LOC). One transcranial Doppler pulse device was developed specifically to function in a centrifuge and another for use in a Mirage 2000, ca...

J. M. Clere G. Ossard D. Lejeune A. Leger A. Roncin

1990-01-01

146

Doppler Signal Analysis and Processing Techniques for Modified 'Porcupine' C-Band Pulse Doppler Radar.  

Science.gov (United States)

The report deals primarily with various doppler signal processing techniques for the Porcupine Weather Radar System. Continuing emphasis is placed on digital data reduction techniques including the fast Fourier transform method of spectral analysis. Pract...

T. Berger E. G. Cox H. L. Groginsky J. M. Kovalik G. A. Works

1968-01-01

147

Pulsed Doppler lidar at QinetiQ  

Science.gov (United States)

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

Pearson, Guy N.

2004-12-01

148

The Doppler shift in a Schwarzschild spacetime  

International Nuclear Information System (INIS)

[en] We demonstrate that in the case of Schwarzschild spacetime the Doppler shift is partially factorized into terms representing relativistic, kinematical and the gravitational contributions. The condition for the complete factorization is derived. Application of these results to the simplest cases and possible implementation in the framework of GPS is briefly discussed

2009-02-23

149

The Doppler shift in a Schwarzschild spacetime  

CERN Multimedia

We demonstrate that in the case of Schwarzschild spacetime the Doppler shift is partially factorized into terms representing relativistic, kinematical and the gravitational contributions. The condition for the complete factorization is derived. Application of these results to the simplest cases and possible implementation in the framework of GPS is briefly discussed.

Radosz, A; Ostasiewicz, K

2009-01-01

150

Developments in laser Doppler blood perfusion monitoring  

Digital Repository Infrastructure Vision for European Research (DRIVER)

peer-reviewed , This paper reviews the development and use of laser Doppler perfusion monitors and imagers. Despite their great success and almost universal applicability in microcirculation research, they have had great difficulty in converting to widespread clinical application. The enormous interest...

Leahy, Martin J.; de Mul, Frits F.M.; Nilsson, Gert E.; Maniewski, Roman; Liebert, Adam

151

The vector Borowiec - Wettzell from Doppler observations.  

Science.gov (United States)

The paper presents the results of a homogeneous elaboration of the results of common Doppler observations carried out at Borowiec and Wettzell stations during different campaigns. The influence of the orbital error model on the determined vector is examined. Obtained results are compared with results of other authors.

Jak?, W.

152

Duplex doppler sonography in portal hypertension  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 wit...

Ni?iforovi? Dijana; Till Viktor; Hadna?ev Dušan; Govor?in Mira; Lu?i? Zorka; Lovrenski Jovan

153

Ultrasonic Doppler color in glaucoma: Concordance study  

International Nuclear Information System (INIS)

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

2005-01-01

154

The medical Doppler in hand surgery: its scientific basis, applications, and the history of its namesake, Christian Johann Doppler.  

Science.gov (United States)

The word Doppler is used synonymously in hand surgery for evaluating patency of vascular structures; however, the science and history behind the Doppler effect are not as well-known. We will present the theories behind the Doppler effect and the history of the person who made this discovery. PMID:18070651

Ghori, Ahmer K; Chung, Kevin C

2007-12-01

155

The medical Doppler in hand surgery: its scientific basis, applications, and the history of its namesake, Christian Johann Doppler.  

UK PubMed Central (United Kingdom)

The word Doppler is used synonymously in hand surgery for evaluating patency of vascular structures; however, the science and history behind the Doppler effect are not as well-known. We will present the theories behind the Doppler effect and the history of the person who made this discovery.

Ghori AK; Chung KC

2007-12-01

156

[Aortic regurgitation: evaluation by pulsed Doppler echocardiography  

UK PubMed Central (United Kingdom)

Ninety-one consecutive patients with aortic regurgitation, either isolated (23 subjects) or associated with other valvular diseases (68 subjects), were studied with pulsed Doppler echocardiography and subsequent aortography, and the results were compared in order to assess the value of the noninvasive technique for a semiquantitative evaluation of the degree of the aortic regurgitation. Both the noninvasive and invasive estimations were graded on a four-point scale. In the long-axis parasternal view, the outflow tract of the left ventricle was divided in four areas going from the aortic valve to the apex. Echo-Doppler grading (from + 1 to +4) was obtained by assessing the area where the abnormal diastolic flow could still be recorded. In the group as a whole, concordant degrees of the aortic insufficiency were obtained in 73 of 91 patients (r = .93; p less than .001); the degree of the aortic regurgitation was overestimated in 8 cases (9%) and underestimated in 10 cases (11%). Most of the discrepancies between the Doppler and the aortographic evaluation were found in patients with intermediate degree (+2, +3) of aortic regurgitation; the degree of discordance was never more than +1 or -1. Correlation between Doppler and aortography was higher in the subjects with pure aortic regurgitation (r = .94, p less than .001) and lower in the subgroup of the subjects with associated mitral stenosis (r = .87, p less than .001). Two-dimensional pulsed Doppler echocardiography is a simple and little time consuming technique that in selected groups of patients can be relied upon for the semiquantitated evaluation of the degree of aortic regurgitation.

Montemurro D; Ronzani G; De Filippi G; Gozzelino G; Orzan F; Presbitero P

1986-06-01

157

[Aortic regurgitation: evaluation by pulsed Doppler echocardiography].  

Science.gov (United States)

Ninety-one consecutive patients with aortic regurgitation, either isolated (23 subjects) or associated with other valvular diseases (68 subjects), were studied with pulsed Doppler echocardiography and subsequent aortography, and the results were compared in order to assess the value of the noninvasive technique for a semiquantitative evaluation of the degree of the aortic regurgitation. Both the noninvasive and invasive estimations were graded on a four-point scale. In the long-axis parasternal view, the outflow tract of the left ventricle was divided in four areas going from the aortic valve to the apex. Echo-Doppler grading (from + 1 to +4) was obtained by assessing the area where the abnormal diastolic flow could still be recorded. In the group as a whole, concordant degrees of the aortic insufficiency were obtained in 73 of 91 patients (r = .93; p less than .001); the degree of the aortic regurgitation was overestimated in 8 cases (9%) and underestimated in 10 cases (11%). Most of the discrepancies between the Doppler and the aortographic evaluation were found in patients with intermediate degree (+2, +3) of aortic regurgitation; the degree of discordance was never more than +1 or -1. Correlation between Doppler and aortography was higher in the subjects with pure aortic regurgitation (r = .94, p less than .001) and lower in the subgroup of the subjects with associated mitral stenosis (r = .87, p less than .001). Two-dimensional pulsed Doppler echocardiography is a simple and little time consuming technique that in selected groups of patients can be relied upon for the semiquantitated evaluation of the degree of aortic regurgitation. PMID:3758583

Montemurro, D; Ronzani, G; De Filippi, G; Gozzelino, G; Orzan, F; Presbitero, P

1986-06-01

158

[Echo-Doppler study of musical heart murmurs].  

Science.gov (United States)

The origin of systolic or diastolic musical murmurs was investigated by means of echo-doppler examination in 51 patients with various cardiac diseases. In all cases a typical doppler spectrum was identified, showing bi-directional clusters of frequencies which were concentric in systole and parallel in diastole. The doppler audio signal was musical. A similar echo-doppler signal was obtained by a diapason vibrating in isotonic solution. These data allowed us to identify the site of the vibrating cardiac structure causing the typical echo-doppler spectrum and characteristic audio signal. PMID:3181660

Boccardi, L; Pennestrì, F; Minardi, G; Di Segni, M; Pucci, E; Biasucci, L M; Loperfido, F; Ferrari, O; Giovannini, E

1988-04-01

159

[Echo-Doppler study of musical heart murmurs  

UK PubMed Central (United Kingdom)

The origin of systolic or diastolic musical murmurs was investigated by means of echo-doppler examination in 51 patients with various cardiac diseases. In all cases a typical doppler spectrum was identified, showing bi-directional clusters of frequencies which were concentric in systole and parallel in diastole. The doppler audio signal was musical. A similar echo-doppler signal was obtained by a diapason vibrating in isotonic solution. These data allowed us to identify the site of the vibrating cardiac structure causing the typical echo-doppler spectrum and characteristic audio signal.

Boccardi L; Pennestrì F; Minardi G; Di Segni M; Pucci E; Biasucci LM; Loperfido F; Ferrari O; Giovannini E

1988-04-01

160

Development of 2-micron airborne coherent Doppler lidar at NICT  

Science.gov (United States)

We have studied a 2-micron airborne coherent Doppler lidar to observe wind profile downward from flying object. We investigated the algorithms required to extract the Doppler-shifted frequency compensating for a speed of the flying object. The airborne experiments were conducted to demonstrate the feasibility of the airborne coherent Doppler lidar from a flying object in 2002, 2004 and 2006. We extracted the Doppler-shifted frequency corresponding to aircraft speed with developed algorithms and obtained wind profiles through airborne experiment. To examine wind profiles measured by the airborne coherent Doppler lidar, we compared those profiles with profiles measured by a GPS-dropsonde and a windprofiler. Although the volume measured by the airborne coherent Doppler lidar system differed spatially and temporally from those by other instruments, the wind profiles observed by the airborne coherent Doppler lidar agreed well with those observed by other instruments.

Ishii, S.; Mizutani, K.; Itabe, T.; Aoki, T.; Ohno, Y.; Horie, H.; Shimabukuro, T.; Sato, A.; Asai, K.

2006-12-01

 
 
 
 
161

A method of generating image derived input function in quantitative 18F-FDG PET study based on the monotonicity of the input and output function curve  

Science.gov (United States)

Objective A method for defining image-derived input function (IDIF) has been introduced and evaluated for the quantification of the regional cerebral metabolic rate of glucose in positron emission tomography studies. Methods The voxels in the brain vasculature are extracted based on the different monotonicity between the input and output function curves. The TACs of such voxels are averaged to get the uncorrected TAC of the brain vasculature. The IDIF was obtained from the raw TAC after correcting for the partial volume and spillover effects by an empirical formula in conjunction with single blood sample and the TAC of the brain tissue. Data from 16 human subjects were used to test the proposed method. The Patlak approach is used to calculate the net FDG clearance with plasma-derived input function (PDIF) and our generated IDIF, respectively. Results the net FDG clearances calculated with the image-derived input function generated by our approach are not only highly correlated (correlation coefficients close to 1) to, but also highly comparable (regression slopes close to 1, and intercepts close to 0) with those calculated with plasma-derived input function. Conclusion The method used in the present work is feasible and accurate.

Zhou, Shan; Chen, Kewei; Reiman, Eric M; Li, De-min; Shan, Baoci

2013-01-01

162

Considerations for Calibrating a Laser Doppler Anemometer  

Energy Technology Data Exchange (ETDEWEB)

Laser Doppler Anemometers have long been the device-of-choice for air velocity measurements due to their avoidance of turbulence induced by insertion-method air velocity measurement devices. At first glance, the use of a Laser Doppler Anemometer (LDA) for calibrating air velocity meters appears to be a relatively simple and straightforward process. As is typical in most metrological applications the process becomes much more complex when attempting to use the apparatus to make high-performance, metrology measurements. This paper focuses on the considerations for calibration of a LDA beginning with a discussion why an LDA needs to be calibrated. Other areas of discussion include alignment of the optics, dealing with imperfections in the alignment process, establishing the traceability of measurements from the apparatus and design and development of and experiences with using a calibration apparatus.

Duncan, Michael L [ORNL; Keck, Joe [ORNL

2010-01-01

163

Positive power Doppler signal in plantar fasciitis.  

UK PubMed Central (United Kingdom)

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

Mendonça JA; Provenza JR; Appenzeller S

2013-02-01

164

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.

1983-01-01

165

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

166

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.)

2008-01-01

167

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

168

Minior Actinide Doppler Coefficient Measurement Assessment  

International Nuclear Information System (INIS)

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

2008-01-01

169

Precision Doppler measurements with steep dispersion.  

UK PubMed Central (United Kingdom)

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

Bortolozzo U; Residori S; Howell JC

2013-08-01

170

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

1991-01-01

171

Transcranial Doppler sonography in familial hemiplegic migraine  

Energy Technology Data Exchange (ETDEWEB)

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

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

1991-02-01

172

[Diagnostic usefulness of uterine artery Doppler].  

Science.gov (United States)

Doppler waves present hemodynamic state of vascular bed. This method is used in a diagnostic of pathological states in pregnancy. Basing on the observation of curve shape of uterine artery blood flow, we may conclude about its vascular resistance, wall tension and amount of blood. Several studies confirmed the opportunity of the use of Doppler uterine artery in a diagnosis and prognosis of complicated pregnancies. The incidence of notch in uterine artery blood flow was observed in pregnancies with incomplete trophoblast invasion and inadequate placentation. Many studies confirmed that bilateral notch might be associated with increased likelihood of different pregnancy complications, particularly pregnancy--induced hypertension (PIH) and intrauterine growth restriction (IUGR). The results of the most recent trials include the possibility of the use Ut-PI in a distinguishing of abnormal biochemical, prenatal tests in chromosomal aberrations and different pathological states in pregnancy such as preeclampsia and fetal hypotrophy. PMID:23437707

Karwasik-Kajszczarek, Katarzyna; Kondracka, Adrianna; Dymanowska-Dyjak, Izabela; Krzyzanowski, Arkadiusz; Kwa?niewska, Anna

2012-12-01

173

Uterine artery Doppler and prediction of preeclampsia.  

Science.gov (United States)

Identifying patients at risk for preeclampsia would allow an increase in perinatal surveillance and possibly decrease the inherent maternal and fetal morbidity and mortality associated with severe preeclampsia and eclampsia. First and second trimester uterine artery Doppler velocimetry is a sensitive screening tool for the detection of preeclampsia and intrauterine growth retardation (IUGR) requiring delivery before 34 weeks. The performance of uterine artery Doppler velocimetry as a screening test depends on the prevalence of the adverse outcome in the studied population and whether the adverse outcomes are assessed individually or collectively as a group. Future research in this area should focus on identification of additional markers that may be incorporated into a prediction model for early identification of patients at risk for adverse outcomes. PMID:21048456

Lovgren, Todd R; Dugoff, Lorraine; Galan, Henry L

2010-12-01

174

Uterine artery Doppler and prediction of preeclampsia.  

UK PubMed Central (United Kingdom)

Identifying patients at risk for preeclampsia would allow an increase in perinatal surveillance and possibly decrease the inherent maternal and fetal morbidity and mortality associated with severe preeclampsia and eclampsia. First and second trimester uterine artery Doppler velocimetry is a sensitive screening tool for the detection of preeclampsia and intrauterine growth retardation (IUGR) requiring delivery before 34 weeks. The performance of uterine artery Doppler velocimetry as a screening test depends on the prevalence of the adverse outcome in the studied population and whether the adverse outcomes are assessed individually or collectively as a group. Future research in this area should focus on identification of additional markers that may be incorporated into a prediction model for early identification of patients at risk for adverse outcomes.

Lovgren TR; Dugoff L; Galan HL

2010-12-01

175

Doppler Effect and Properties of Light  

Science.gov (United States)

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

Robison, David

176

On Doppler tracking in cosmological spacetimes  

Energy Technology Data Exchange (ETDEWEB)

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

Carrera, Matteo; Giulini, Domenico [Physikalisches Institut, Albert-Ludwigs-Universitaet, Hermann-Herder-Strasse 3, D-79104 Freiburg i. Br. (Germany)

2006-12-21

177

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.

2003-01-01

178

A Doppler flowmeter for use in theatre.  

UK PubMed Central (United Kingdom)

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)

Beard JD; Evans JM; Skidmore R; Horrocks M

1986-11-01

179

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

180

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; Maria Cristina Chammas; Giovanni Guido Cerri

2008-01-01

 
 
 
 
181

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; Sebnem Orguc; Bilal Gumus; Veli Ayyildiz; Yuksel Pabuscu

2008-01-01

182

An efficient algorithm to remove low frequency Doppler signals in digital Doppler systems.  

UK PubMed Central (United Kingdom)

In color flow imaging, a high flow map rate in combination with a reasonable width of the map and good velocity resolution is essential to properly appreciate the time-dependent phenomena. The velocity resolution depends on the length of the signal segment considered in combination with the settling time of the high pass filter used to eliminate transients and low frequency artifacts. The latter can be reduced by appropriate processing. This paper presents an algorithm to suppress low frequency Doppler signals effectively and efficiently, while all the data points within the segment considered contribute equally to the average Doppler frequency computed. The algorithm is applied to computer generated Doppler signals to evaluate their time and frequency behavior. It is concluded that the proposed scheme functions adequately under various signal conditions.

Hoeks AP; van de Vorst JJ; Dabekaussen A; Brands PJ; Reneman RS

1991-04-01

183

An efficient algorithm to remove low frequency Doppler signals in digital Doppler systems.  

Science.gov (United States)

In color flow imaging, a high flow map rate in combination with a reasonable width of the map and good velocity resolution is essential to properly appreciate the time-dependent phenomena. The velocity resolution depends on the length of the signal segment considered in combination with the settling time of the high pass filter used to eliminate transients and low frequency artifacts. The latter can be reduced by appropriate processing. This paper presents an algorithm to suppress low frequency Doppler signals effectively and efficiently, while all the data points within the segment considered contribute equally to the average Doppler frequency computed. The algorithm is applied to computer generated Doppler signals to evaluate their time and frequency behavior. It is concluded that the proposed scheme functions adequately under various signal conditions. PMID:1858218

Hoeks, A P; van de Vorst, J J; Dabekaussen, A; Brands, P J; Reneman, R S

1991-04-01

184

Doppler pressure field deduced from the Doppler velocity field in an observation plane in a fluid.  

UK PubMed Central (United Kingdom)

A new method is developed for a nondisturbing and quantitative measurement of the pressure at an arbitrary point in a flowing fluid in three-dimensional (3-D) space. In this method, after measuring the velocity field in the observation plane (scanning plane) using the pulsed Doppler technique, the velocity component orthogonal to the Doppler velocity is deduced, taking the law of conservation of mass (the equation of continuity) into consideration. Then, the pressure, "Doppler pressure," is calculated from the acceleration. It is expected that, when this method is applied to cardiology in clinical medicine, it will be very useful as a clinical diagnostic tool for the practical analysis and estimation of hemodynamics in the blood flow in the heart chambers, because the pressure field can be displayed as a 2-D contour.

Ohtsuki S; Tanaka M

2003-10-01

185

Rotational Doppler effect in left-handed materials  

CERN Document Server

We explain the rotational Doppler effect associated with light beams carrying with orbital angular momentum in left-handed materials (LHMs). We demonstrate that the rotational Doppler effect in LHMs is unreversed, which is significantly different from the linear Doppler effect. The physics underlying this intriguing effect is the combined contributions of negative phase velocity and inverse screw of wave-front. In the normal dispersion region, the rotational Doppler effect induces a upstream energy flow but a downstream momentum flow. In the anomalous dispersion region, however, the rotational Doppler effect produces a downstream energy flow but a upstream momentum flow. We theoretically predict that the rotational Doppler effect can induce a transfer of angular momentum of the LHM to orbital angular momentum of the beam.

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

2008-01-01

186

Influence of Doppler Bin Width on GNSS Detection Probabilities  

CERN Multimedia

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

Geiger, Bernhard C

2011-01-01

187

Doppler-compensated three-photon electromagnetically induced transparency  

CERN Multimedia

We demonstrate Doppler-compensated bright and dark states in a resonant four-level atomic system. The spectral features are the result of electromagnetically induced transparency (EIT) and absorption (EIA) and are sub-Doppler due to the compensation of Doppler shifts with AC Stark shifts. We demonstrate the effect using a three-photon cascade system to Rydberg states in Cs vapor, however, the results apply to any four-level cascade or N-type system.

Carr, Christopher; Sargsyan, Armen; Sarkisyan, David; Adams, Charles S; Weatherill, Kevin J

2012-01-01

188

The image of urachus adenocarcinoma on Doppler ultrasonography  

Energy Technology Data Exchange (ETDEWEB)

Malignant urachal lesions are exceedingly rare and occur predominantly in adult life. In this case report, an adult patient with urachal carcinoma is presented with abdominal plain film, intravenous urography, gray-scale ultrasonography (US), Doppler US, and computed tomography (CT). Doppler US successfully showed the neovascularity with low resistive index value in the urachus tumor. We believe that Doppler US examination is helpful in the differential diagnosis of urachal carcinoma.

Oyar, Orhan E-mail: o_oyar@hotmail.com; Yesildag, Ahmet; Gulsoy, Ufuk Kemal; Perk, Hakki

2002-10-01

189

The image of urachus adenocarcinoma on Doppler ultrasonography  

International Nuclear Information System (INIS)

Malignant urachal lesions are exceedingly rare and occur predominantly in adult life. In this case report, an adult patient with urachal carcinoma is presented with abdominal plain film, intravenous urography, gray-scale ultrasonography (US), Doppler US, and computed tomography (CT). Doppler US successfully showed the neovascularity with low resistive index value in the urachus tumor. We believe that Doppler US examination is helpful in the differential diagnosis of urachal carcinoma

2002-01-01

190

Calculation of the Doppler broadening function using Fourier analysis  

International Nuclear Information System (INIS)

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

2010-01-01

191

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

2005-01-01

192

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.

Giugno Luca; Zanier Francesca; Luise Marco

2007-01-01

193

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; Francesca Zanier; Marco Luise

2007-01-01

194

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

CERN Document Server

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

Wang, J; Yan, S; Liu, T; Zhang, T; Wang, Junmin; Wang, Yanhua; Yan, Shubin; Liu, Tao; Zhang, Tiancai

2003-01-01

195

Plasma rotation profile measurements using Doppler reflectometry  

International Nuclear Information System (INIS)

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

2004-06-01

196

Tecnología Doppler y movimientos respiratorios fetales  

Scientific Electronic Library Online (English)

Full Text Available 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 una adecuada función de la circulación útero placentaria y feto placentaria, sino de otras estructuras orgánicas, es por lo que este método abre una línea de inves (more) tigación 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 expo (more) se 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.

García Noguera de Yegüez, Marisol; Inaudy Bolívar, Efraín

2008-03-01

197

Tecnología Doppler y movimientos respiratorios fetales  

Directory of Open Access Journals (Sweden)

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

2008-01-01

198

Doppler cooling to the Quantum limit  

CERN Document Server

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

Chalony, Maryvonne; Klappauf, Bruce; Wilkowski, David

2011-01-01

199

Analysis of Doppler Activation Measurements in ZEBRA  

International Nuclear Information System (INIS)

[en] An analysis is made of some recent Doppler activation foil measurements in the UKAEA zero-power fast reactor ZEBRA. A model is used to approximate the system of a foil, oven and heterogeneous reactor by a foil and homogenized reactor. The collision probabilities obtained by this reduction are used in the computer programme SDR-GENEX which produces a detailed continuous-energy slowing-down spectrum in the foil for the range 0-15 keV. The spectrum above 15 keV is obtained using the multigroup diffusion code SCRAMBLE. The measured (n, ?) activation ratio for a 12.19 mm X 0.254 mm U3O8/Ni foil is 1.024 ±0.003 in ZEBRA core 6A and 1.020 ± 0.003 in core 6D compared with the calculated values 1.022 and 1.020, respectively. The model, although approximate in its treatment of homogenizing the reactor core, is a useful tool for understanding the more important physics of the (n, ?) activation experiment. A comparison is made of the calculated energy distributions of the Doppler effect in the foil and in the core. It shows the median energy of each distribution to be at 900 eV and 1550 eV, respectively. This relative displacement is attributed to the differing degree of self-shielding of the 238U resonances, in the foil and in the core. In the core the background scattering cross-section is about 50 barns per 238U atom compared with an effective scattering cross-section of 250 000 barns in the. thin foil. The effect of this dilution in the foil is to lower the Doppler contribution from the predominantly scattering resonances around 1 or 2 keV and to increase the percentage contribution of the strongly absorbing low-energy resonances. We observe this as a relative shift in energy of the foil and core Doppler distributions. The analysis shows that, by equalizing the scattering cross-section per absorbing atom in the foil and core, the activation ratio and its energy distribution are also approximately equalized in the foil and core. We may therefore optimize the design of the activation experiment. For example, in a typical fast reactor core, a long circular cylinder of natural uranium would require a diameter of 0.53 cm, or a 2.54-cm-diam. disc a thickness of 0.33 cm, to produce an optimum response. (author)

1967-11-03

200

[Study of infectious endocarditis using Doppler echocardiography  

UK PubMed Central (United Kingdom)

Infective endocarditis is still a common and serious disease. Echocardiography is an essential complementary investigation in this condition. Its value in the diagnosis of valvular vegetations has become more accurate since the introduction of two-dimensional and transesophageal echocardiography. Transesophageal echocardiography is currently the most reliable non-invasive technique for demonstrating small vegetations of less than 5 mm diameter. The diagnosis and surveillance of complications (valvular destruction, ring abscess) are also privileged indications of transthoracic and transesophageal echocardiography coupled with intracardiac Doppler blood flow studies. The finding of these lesions may sometimes lead to early surgical management.

Roudaut R; Dallocchio M

1990-05-01

 
 
 
 
201

Transcranial Doppler Examination and Its Clinical Usage  

Directory of Open Access Journals (Sweden)

Full Text Available Transcranial Doppler sonography provides information on the velocity of blood flow in the major intracranial arteries and its direction in relation to the ultrasound probe. It is a non-invasive, inexpensive, easy, and repeatable method and can be performed at the bedside. It provides useful information on cerebral circulations, changes in the intracranial pressure, on the diagnosis of patent foramen ovale, and in the evaluation of risk factors for stroke. Other indications include monitoring of intracranial arterial occlusions and stenosis, detection of emboli, and assessment of cerebrovascular reactivity.

Talip ASIL

2002-01-01

202

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

203

Comparison of Triature Doppler Velocimetry and Visar  

International Nuclear Information System (INIS)

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

2010-08-01

204

Color Doppler Ultrasonographic Features of Hashimoto's Thyroiditis  

International Nuclear Information System (INIS)

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

1995-01-01

205

Doppler echocardiography in athletes from different sports.  

UK PubMed Central (United Kingdom)

BACKGROUND: Studies have shown cardiac changes induced by intense and regular physical activity. The purpose of this study was to evaluate cardiac structures and function in soccer players, cyclists and long-distance runners, and compare them with non-athlete controls. MATERIAL AND METHODS: Cardiac structural, systolic, and diastolic function parameters in 53 athletes and 36 non-athlete controls were evaluated by Doppler echocardiography. RESULTS: Athletes presented higher left atrial volume, left ventricular (LV) thickness, and LV and right ventricular (RV) diastolic diameters (LVDD and RVDD, respectively) compared to non-athletes. Left atrium and LVDD were higher in cyclists than runners, and RVDD was higher in cyclists than soccer players. LV mass index was higher in athletes, and cyclists had higher values than runners and soccer players. LV systolic function did not differ significantly between groups. The only altered index of LV diastolic function was a higher E/A ratio in cyclists compared to controls. There was no difference in LV E/E' ratio. RV systolic function evaluated by tissue Doppler imaging was higher in cyclists and soccer players than runners. There were no conclusive differences in RV diastolic function. CONCLUSIONS: Soccer players, runners and cyclists had remodeling of left and right ventricular structures compared to controls. Cardiac remodeling was more intense in cyclists than runners and soccer players.

Moro AS; Okoshi MP; Padovani CR; Okoshi K

2013-01-01

206

Doppler Spread Estimation by Subspace Tracking for OFDM Systems  

CERN Multimedia

This paper proposes a novel maximum Doppler spread estimation algorithm for OFDM systems with the comb-type pilot pattern. By tracking the drifting delay subspace of the multipath channel, the time correlation function is measured at a high accuracy, which accordingly improves the estimation accuracy of the maximum Doppler spread considerably.

Zhao, Xiaochuan; Yang, Ming; Wang, Wenbo

2008-01-01

207

Transit time broadening: A pulsed Doppler ultrasound perspective  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Many studies on transit time broadening have been performed to characterize its effect on the Doppler spectrum. However, the dependence of transit time broadening on an important pulsed Doppler ultrasound parameter - the range gate used for depth localization - has not been rigorously addressed. The...

Yu, ACH; Steinman, AH; Lui, EYL; Cobbold, RSC

208

A laser Doppler method for noninvasive measurement of flow velocity  

Energy Technology Data Exchange (ETDEWEB)

Laser Doppler velocimetry is a powerful optical technique for noninvasively obtaining experimental flow-velocity data. This paper describes the principle of operation and various optical configurations of the laser Doppler velocimeter. As a sample application, we describe an experimental apparatus for measuring the velocity flow field around a cylinder, and give our experimental results.

Biggs, G.L.

1986-11-25

209

Imaging doppler velocimeter with downward heterodyning in the optical domain  

Energy Technology Data Exchange (ETDEWEB)

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

Reu, Phillip L; Hansche, Bruce D

2013-05-21

210

Transcranial Doppler detection of anterior cerebral artery vasospasm.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The performance of transcranial Doppler in the detection of anterior cerebral artery vasospasm and vasospasm in patients after subarachnoid haemorrhage was analysed. Transcranial Doppler and cerebral angiography were performed within the same 24 hours on each of 41 patients with acute subarachnoid h...

Lennihan, L; Petty, G W; Fink, M E; Solomon, R A; Mohr, J P

211

A simulation of transit time effects in Doppler ultrasound signals.  

UK PubMed Central (United Kingdom)

A signal model is proposed which can be used to study frequency extraction techniques for Doppler ultrasound. The signal is based on the physics of the Doppler process and depends on a sliding window used to average a set of independent Gaussian random numbers. This window is related to the shape of the sample volume for the Doppler pulse and depends on the Doppler angle. Simulation results compare favorably with results from flow experiments in terms of the variance of the estimated Doppler shift, the shape of the power spectra and the behavior of the signals with respect to Burg autoregressive power spectra. A potential use of the signal in the study of spectral analysis techniques is presented.

Jones SA; Giddens DP

1990-01-01

212

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.

C. Bianchi; D. Altadill

2005-01-01

213

Predictable Progressive Doppler Deterioration in IUGR - Does it really exist?  

UK PubMed Central (United Kingdom)

OBJECTIVE: An objective of the PORTO Study was to evaluate multi-vessel Doppler changes in a large cohort of IUGR fetuses to establish whether a predictable progressive sequence of Doppler deterioration exists and to correlate these Doppler findings with respective perinatal outcomes. METHODS: Over 1,100 unselected consecutive ultrasound-dated singleton pregnancies with EFW<10th centile were recruited between January 2010 and June 2012. Eligible pregnancies were assessed by serial Doppler interrogation of umbilical (UA) and middle cerebral (MCA) arteries, ductus venosus (DV), aortic isthmus (AoI) and myocardial performance index (MPI). Intervals between Doppler changes and patterns of deterioration were recorded and correlated with respective perinatal outcomes. RESULTS: Our study of 1,116 non-anomalous fetuses comprised 7,769 individual Doppler datapoints. 511 (46%) patients had an abnormal UA, 300 (27%) had an abnormal MCA and 129 (11%) had an abnormal DV Doppler. The classic pattern from abnormal UA to MCA to DV existed but no more frequently than any of the other potential pattern. Doppler interrogation of the UA and MCA remains the most useful and practical tool in identifying fetuses at risk of adverse perinatal outcome, capturing 88% of all adverse outcomes. CONCLUSION: In contrast to previous reports, we have demonstrated multiple potential patterns of Doppler deterioration in this large prospective cohort of IUGR pregnancies which calls into question the usefulness of multi-vessel Doppler assessment to inform frequency of surveillance and timing of delivery of IUGR fetuses. These data will be critically important for planning any future intervention trials.

Unterscheider J; Daly S; Geary MP; Kennelly MM; McAuliffe FM; O'donoghue K; Hunter A; Morrison JJ; Frcog GB; Dicker P; Tully EC; Malone FD

2013-08-01

214

Direct comparison of laser Doppler flowmetry and laser Doppler imaging for assessment of experimentally-induced inflammation in human skin  

DEFF Research Database (Denmark)

Laser Doppler imaging (LDI) and laser Doppler flowmetry (LDF) can measure localized skin perfusion. The purpose of the study was to directly compare LDF with LDI as a tool for measuring skin blood changes in an experimental model of chemically-induced skin inflammation.

Petersen, Lars J

2013-01-01

215

[The Doppler Simulator DS 81. A new calibration method for ultrasound-cw-Doppler blood flow measurement devices  

UK PubMed Central (United Kingdom)

Quality assurance in commercial cw-Doppler devices demands the use of special techniques in providing reproducible, optimized patient examination conditions for the individual instrument, and to permit a comparison with results obtained by other equipment. Equipment can be tested on two different technical levels: by checking the total performance by means of a Doppler phantom, or by testing the relevant components by means of electrical test signals. The use of Doppler phantoms involves certain drawbacks with respect to some equipment parameters and the routine equipment check. In the German Federal Republic, new official regulations (KBV), including the minimum requirements for Doppler equipment have been issued. To fulfil the legal requirements, a special test device, The Doppler Simulator DS 81 (1981), has proved suitable. The device provides a graduated scale of discrete, synthetic Doppler frequencies; these are fed into the Doppler equipment under test, and the response is recorded on the instrument's strip chart recorder or viewing screen. They are used as reference frequencies and for calibration. This method represents a further step towards reproducible or quantitative Doppler sonography.

Reuter R; Trier HG

1983-09-01

216

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

217

Ultrasonic intrusion sensor using the Doppler effect; Choonpa Doppler hoshiki shinnyu sensor  

Energy Technology Data Exchange (ETDEWEB)

For vehicle anti-theft alarm systems which cope with vehicle and car component theft, EU initiated vehicle security regulations from Jan 1997. Also, the insurance industry has instituted the insurance certification of vehicle anti-theft alarm systems. We have developed an ultrasonic intrusion sensor using the doppler effect for vehicle anti-theft alarm systems specifically for these EU regulations and insurance certification. 2 refs., 7 figs., 1 tab.

Kani, H.; Iwasaki, N.; Goto, M. [Nippon Soken, Inc., Tokyo (Japan); Tsuzuki, T.; Nakamura, T. [Denso Corp., Aichi (Japan)

1997-10-01

218

Signal Processing Schemes for Doppler Global Velocimetry  

UK PubMed Central (United Kingdom)

Two schemes for processing signals obtained from the Doppler globalvelocimeter are described. The analog approach is a simple, real timemethod for obtaining an RS-170 video signal containing the normalizedintensity image. Pseudo colors are added using a monochromatic framegrabber producing a standard NTSC video signal that can be monitoredand/or recorded. The digital approach is more complicated, butmaintains the full resolution of the acquisition cameras with thecapabilities to correct the signal image for pixel sensitivity variationsand to remove of background light. Prototype circuits for each schemeare described and example results from the investigation of the vorticalflow field above a 75-degree delta wing presented.IntroductionThe use of high lift devices to increase the performance envelope ofadvanced aircraft results in flow fields comprised of vortical andreversed flows with turbulent separations interacting with lift andcontrol surfaces. These complicated flow...

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

219

Widefield laser doppler velocimeter: development and theory.  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-03-01

220

Laser Doppler vibrometry: new ENT applications  

Science.gov (United States)

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

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

1996-12-01

 
 
 
 
221

Unambiguous Doppler Shift Estimation for Moving  

UK PubMed Central (United Kingdom)

This paper presents a new methodology to retrieveslant-range velocity estimates of moving targets inducing Dopplershiftsbeyond the Nyquist limit determined by the pulse repetition frequency (PRF). The proposed approach exploitsthe linear dependence (not subject to PRF limitations) of the Doppler-shift with respect to the slant-range velocity,ateachwavelength. Basically,we propose an algorithm to compute the skew of the two-dimensional spectral signature of amoving target. Distinctive features of this algorithm are its ability to cope with strong range migration and its efficiencyfrom the computational point of view. By combining the developed scheme to retrieve the slant-range velocitywithamethodology proposed elsewhere to estimate the velocityvector magnitude, the full velocityvector is unambiguouslyretrieved without increasing the mission PRF. The effectiveness of the method is illustrated with simulated and realdata. As an example, slant-range velocities of moving objects with velocities between 6 and 12 times the Nyquist velocityare estimated with accuracy better than 3%.

Jos'e M. B. Dias; Paulo A. C. Marques

222

Fractal fluctuations in transcranial Doppler signals  

Science.gov (United States)

Cerebral blood flow (CBF) velocity measured using transcranial Doppler ultrasonography (TCD) is not strictly constant, but has both a systematic and random component. This behavior may indicate that the axial blood flow in the middle cerebral artery is a chaotic process. Herein we use the relative dispersion, the ratio of the standard deviation to the mean, to show by systematically aggregating the data that the correlation in the beat-to-beat CBF time series is a modulated inverse power law. This scaling of the CBF time series indicates the existence of long-time memory in the underlying control process. We argue herein that the control system has allometric properties that enable it to maintain a relatively constant brain perfusion.

West, B. J.; Zhang, R.; Sanders, A. W.; Miniyar, S.; Zuckerman, J. H.; Levine, B. D.

1999-03-01

223

Transcranial doppler, EEG and SEP monitoring  

Directory of Open Access Journals (Sweden)

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

H. Gehring; L. Meyer zu Westrup; S. Boye; A. Opp; U. Hofmann

2009-01-01

224

Doppler imaging of magnetic Ap stars  

Energy Technology Data Exchange (ETDEWEB)

An application of the Doppler imaging technique is presented for mapping the surface distribution of elements on rapidly rotating magnetic Ap stars. This method uses the principles of maximum entropy image reconstruction to solve a matrix equation relating the local equivalent width distribution on the surface of a star to a sequence of time resolved spectral lines profiles. The method's ability at recovering both the shape and location of abundance features strictly from spectral line profile variations is demonstrated by reconstruction several test input distributions. The method can also accurately recover both depleted and enhanced abundance features. Using high signal-to-noise and high resolution spectral line profiles obtained at Lick Observatory, this technique was used to derived the distribution of silicon on 7 stars and chromium on 6 stars. The Doppler images show that silicon and possibly chromium is depleted in spots coincident with the magnetic poles of these stars, and enhanced near regions where one expects the field lines to be horizontal. These results are consistent with the predictions of diffusion theory and provide strong direct evidence that selective diffusion is the mechanism responsible for the spectral variations. Finally, these images are used to derive the magnetic field configuration in these stars. The stars show a bimodal distribution in obliquity angles centered on 75{degree} and 50{degree}, and decentering parameters near 0.2 stellar radii. The non-axisymmetric fields evident in the abundance distributions are consistent with the hypothesis that a redistribution of surface fields occurs in rapidly rotating magnetic Ap stars.

Hatzes, A.P.

1988-01-01

225

Doppler imaging of magnetic Ap stars  

International Nuclear Information System (INIS)

An application of the Doppler imaging technique is presented for mapping the surface distribution of elements on rapidly rotating magnetic Ap stars. This method uses the principles of maximum entropy image reconstruction to solve a matrix equation relating the local equivalent width distribution on the surface of a star to a sequence of time resolved spectral lines profiles. The method's ability at recovering both the shape and location of abundance features strictly from spectral line profile variations is demonstrated by reconstruction several test input distributions. The method can also accurately recover both depleted and enhanced abundance features. Using high signal-to-noise and high resolution spectral line profiles obtained at Lick Observatory, this technique was used to derived the distribution of silicon on 7 stars and chromium on 6 stars. The Doppler images show that silicon and possibly chromium is depleted in spots coincident with the magnetic poles of these stars, and enhanced near regions where one expects the field lines to be horizontal. These results are consistent with the predictions of diffusion theory and provide strong direct evidence that selective diffusion is the mechanism responsible for the spectral variations. Finally, these images are used to derive the magnetic field configuration in these stars. The stars show a bimodal distribution in obliquity angles centered on 75 degree and 50 degree, and decentering parameters near 0.2 stellar radii. The non-axisymmetric fields evident in the abundance distributions are consistent with the hypothesis that a redistribution of surface fields occurs in rapidly rotating magnetic Ap stars

1988-01-01

226

[Doppler color ultrasonography of the normal penis].  

Science.gov (United States)

The penile blood vessels arise from the internal pudendal artery. After the arcuate ligament the artery is usually called the main penile artery. Afterwards the vessel is divided into the dorsal penile artery, which is thin, and the cavernosal artery, which enter the corpus cavernosum on the supero-medial surface of the penis. The branches of this artery are called the arteriae helicinas that subsequently divide in smaller vessels that communicate with the lacunae of the corpus cavernosum. The venous blood flow is drained into the venous plexus beneath the tunica albuginea. The emissary veins perforate the albuginea and the blood is drained by the venae circumflexae into the deep dorsal vein. Color-Doppler sonography allows actually to depict all these vessels and to study the blood flow in these structures with the exclusion of the lacunar spaces. To detect slow flows the technical parameters are very important and the Doppler angle must be always less than 60 degrees. During pharmacologically induced erection the peak systolic velocity in the cavernosal artery shows different values, according to the time of measurements. Initially high systolic velocity is detected (over 35 cm/s) and high diastolic flow (8-15 cm/s) due to low intracavernosal resistance. After veno-occlusive mechanism activation, an increase of flow is normally observed with peak systolic velocity up to 80-120 cm/s associated to progressive decrease of diastolic flow. In the initial phase of the erection the venous flow is characterized with elevated blood velocity in the circumflex and deep dorsal veins. Afterwards with progressive erection the venous flow reduces to disappear completely with full rigidity. Three dimensional US allows a better visualization of the morphology, number and distribution of the vascular tree of the penis. PMID:11221073

Barozzi, L; Pavlica, P; Piervitali, D

2000-12-01

227

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; Maria Cristina Chammas; Giovanni Guido Cerri

2008-01-01

228

Analysis of INS Derived Doppler Effects on Carrier Tracking Loop  

Science.gov (United States)

Tracking dynamics on the GPS signal is still a big challenge to the receiver designer as the operating conditions are becoming more volatile. Optimizing the stand-alone system for dynamics generally degrades the accuracy of measurements. Therefore, an inertial navigation system (INS) is integrated with GPS to address this issue. Doppler derived from INS can be used to aid the carrier tracking loop for improving the performance under dynamic conditions. However, the derived doppler does not truly reflect the GPS signal doppler due to errors in inertial sensors. As the tracking loop bandwidth is reduced significantly in ultra-tightly integrated systems, any offsets in the aiding doppler creates undesired correlations in the tracking loop resulting in sub-optimal performance of the loop. The paper addresses this issue and also provides a mitigating mechanism to reduce the effects of incorrect estimates of the doppler. It is shown that doppler offsets resulting in a bias in the tracking loop can be appropriately modelled and removed. Mathematical algorithms pertaining to this are provided and the results are summarized. Simulations show that the bias due to aiding doppler offsets could be effectively addressed by appropriate modelling.

Babu, Ravindra; Wang, Jinling

2005-09-01

229

Clutter reduction using Doppler sonar in a harbor environment.  

Science.gov (United States)

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

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

2012-11-01

230

Clutter reduction using Doppler sonar in a harbor environment.  

UK PubMed Central (United Kingdom)

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

Yang TC; Schindall J; Huang CF; Liu JY

2012-11-01

231

Intraoperative Doppler assessment of gastric tube perfusion in esophagogastroplasty.  

UK PubMed Central (United Kingdom)

BACKGROUND: Intraoperative Doppler ultrasonography is a non-invasive method with a great potential for the assessment of perfusion in surgery. This study aimed to determine the accuracy of Doppler ultrasonography in the assessment of blood flow on the top of an Akiyama-fashioned stomach tube for esophagus substitution. A secondary point of interest was the real length gained after construction of the gastric tube. MATERIALS AND METHODS: The Ivor-Lewis two stage gastro-esophagectomy was performed in 22 patients with carcinoma of the lower third of the esophagus. Vascularization of the gastric tube was assessed in every patient by Doppler sonographies after every separate step of stomach mobilization. Control arteriographies were performed at 4 major steps of mobilization to evaluate the accuracy of Doppler measurements. RESULTS: Doppler assessment showed a sensitivity of 50 to 95%, specificity of up to 97% and overall accuracy between 95% and 75% during the separate steps of construction of the gastric tube. An approximate length of 4 cm was gained after the final mobilization and tubularization of the stomach. CONCLUSION: Our clinical trial revealed an excellent agreement between the results of Doppler sonography and arteriography. Doppler sonography proved to be a precise technique for the evaluation of stomach perfusion, especially for the needs of tissue viability assessment of the stomach tube in esophageal surgery.

Tsekov C; Belyaev O; Tcholakov O; Tcherveniakov A

2006-05-01

232

A method for generating image-derived input function in quantitative 18F-FDG PET study based on the monotonicity of the input and output function curve.  

UK PubMed Central (United Kingdom)

OBJECTIVE: A method of defining the image-derived input function (IDIF) was introduced and evaluated for the quantification of the regional cerebral metabolic rate of glucose in PET studies. METHODS: The voxels in the brain vasculature are extracted on the basis of the different monotonicities between the input and the output function curves. Time activity curves (TACs) of such voxels are averaged to obtain the uncorrected TAC of the brain vasculature. The IDIF was obtained from the raw TAC after correcting for the partial volume and spillover effects by an empirical formula in conjunction with a single blood sample and the TAC of the brain tissue. Data from 16 patients were used to test the proposed method. The Patlak approach is used to calculate the net fluoro-2-deoxyglucose clearance with plasma-derived input function and our generated IDIF, respectively. RESULTS: The net fluoro-2-deoxyglucose clearances calculated with the IDIF generated by our approach are not only highly correlated (correlation coefficients close to 1) to, but also highly comparable (regression slopes close to 1 and intercepts close to 0) with those calculated with plasma-derived input function. CONCLUSION: The method used in the present work is feasible and accurate.

Zhou S; Chen K; Reiman EM; Li DM; Shan B

2012-04-01

233

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

International Nuclear Information System (INIS)

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

2007-12-07

234

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

235

Observing molecular spinning via the rotational Doppler effect  

Science.gov (United States)

When a wave is reflected from a moving object, its frequency is Doppler shifted. Similarly, when circularly polarized light is scattered from a rotating object, a rotational Doppler frequency shift may be observed, with manifestations ranging from the quantum world (fluorescence spectroscopy, rotational Raman scattering and so on) to satellite-based global positioning systems. Here, we observe for the first time the Doppler frequency shift phenomenon for a circularly polarized light wave propagating through a gas of synchronously spinning molecules. An ensemble of such spinning molecules was produced by double-pulse laser excitation, with the first pulse aligning the molecules and the second (linearly polarized at a 45° angle) causing a concerted unidirectional rotation of the `molecular propellers'. We observed the resulting rotating birefringence of the gas by detecting a Doppler-shifted wave that is circularly polarized in a sense opposite to that of the incident probe.

Korech, Omer; Steinitz, Uri; Gordon, Robert J.; Averbukh, Ilya Sh.; Prior, Yehiam

2013-09-01

236

Learning Based Falling Detection Using Multiple Doppler Sensors  

Directory of Open Access Journals (Sweden)

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

Shoichiro Tomii; Tomoaki Ohtsuki

2013-01-01

237

"DERIVATION" OF THE DE BROGLIE RELATION FROM THE DOPPLER EFFECT  

Energy Technology Data Exchange (ETDEWEB)

In this note we assume that all particles have wave properties and hence must exhibit a Doppler shift when they reflect from a massive slowly receding mirror. We then show that particles must satisfy the de Broglie relation.

Crawford, Frank S.

1980-10-01

238

Extending emission line Doppler tomography ; mapping modulated line flux  

CERN Multimedia

Emission line Doppler tomography is a powerful tool that resolves the accretion flow in binaries on micro-arcsecond scales using time-resolved spectroscopy. I present an extension to Doppler tomography that relaxes one of its fundamental axioms and permits the mapping of time-dependent emission sources. Significant variability on the orbital period is a common characteristic of the emission sources that are observed in the accretion flows of cataclysmic variables and X-ray binaries. Modulation Doppler tomography maps sources varying harmonically as a function of the orbital period through the simultaneous reconstruction of three Doppler tomograms. One image describes the average flux distribution like in standard tomography, while the two additional images describe the variable component in terms of its sine and cosine amplitudes. I describe the implementation of such an extension in the form of the maximum entropy based fitting code MODMAP. Test reconstructions of synthetic data illustrate that the technique...

Steeghs, D

2003-01-01

239

The determinations of station coordinates from Doppler observations  

Science.gov (United States)

This paper presents contribution of Astronomical Latitude Observatory in Borowiec to Doppler observations performance and elaboration. Analysis of periodical variation of Borowiec coordinates and changes of Borowiec-Borowa Gora vector are described more closely.

Jaks, Waldemar; Zeller, Krzysztof

240

Ultrasonic Doppler methods to extract signatures of a walking human.  

UK PubMed Central (United Kingdom)

Extraction of Doppler signatures that characterize human motion has attracted a growing interest in recent years. These Doppler signatures are generated by various components of the human body while walking, and contain unique features that can be used for human detection and recognition. Although, a significant amount of research has been done in radio frequency regime for human Doppler signature extraction, considerably less has been done in acoustics. In this work, 40 kHz ultrasonic sonar is employed to measure the Doppler signature generated by the motion of body segments using different electronic and signal processing schemes. These schemes are based on both analog and digital demodulation with homodyne and heterodyne receiver circuitry. The results and analyses from these different schemes are presented.

Mehmood A; Sabatier JM; Damarla T

2012-09-01

 
 
 
 
241

USAGE OF LASER DOPPLER FLOWMETRY FOR CHILDREN BLOOD MICROCIRCULATION ASSESSMENT  

Directory of Open Access Journals (Sweden)

Full Text Available The individual features of blood microcirculation were investigated for children of 6-9 years. The childrennormative of blood microcirculation were revealed due to laser Doppler flow data.

Anosov I. P.; Antonovskaya L. V.; Gornaya O. I.; Stanishevskaya T. I.; Mankovskaya L. N.; Yusupova O.V.; Khomatov V. X.

2011-01-01

242

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; Demir N; Koyuncu F; Goktay Y

1996-01-01

243

Microembolus Detection by Transcranial Doppler Sonography: Review of the Literature  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transcranial Doppler can detect microembolic signals which are characterized by unidirectional high intensity increase, short duration, random occurrence, and a “whistling” sound. Microembolic signals have been detected in a number of clinical settings: carotid artery stenosis, aortic arch plaques, ...

Vukovi?-Cvetkovi?, Vlasta

244

Role of transcranial Doppler ultrasonography in acute stroke  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Transcranial Doppler (TCD) ultrasonography is the only noninvasive examination that provides a reliable evaluation of intracranial blood flow patterns in real-time, adding physiological information to the anatomical information obtained from other neuroimaging modalities. TCD is ...

Sharma Vijay; Venketasubramanian N; Khurana Dheeraj; Tsivgoulis Georgios; Alexandrov Andrei

245

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

246

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

1997-01-01

247

Electromagnetic radiofrequency interference with Doppler equipment.  

UK PubMed Central (United Kingdom)

Doppler ultrasound equipments incorporate radiofrequency (RF) receivers operating at the microvolt level and are liable to interference from radiated fields and mains disturbances. The most significant interference routes are: radiation from radio broadcast, paging, communication and diathermy picked up on the transducer and patient acting as an aerial; and mains disturbances from diathermy, x-ray sets, motors and thyristor controls, etc, reaching the equipment interior. Direct mains interference can be reduced by proper design incorporating a mains filter, a low RF leakage enclosure, a ground plane, careful layout and further screening of the receiver circuits. Pick-up via the transducer occurs even if the signal leads are completely screened because an RF potential can exist between transducer and equipment enclosure due to the considerable impedance at RF of any wire or cable, typically 70 omega at 5 MHz for 2 m. This potential, reduced by about 50-60 dB, appears at the receiver input because of imperfect common mode rejection of the coupling cable. As a result, induced voltages above 100-300 microV may cause problems. It is shown that such levels can easily result from the interfering field strengths of 1 mV m-1 or more that may be experienced in a hospital environment. On the other hand, field strengths of 300 microV m-1, as generally allowed by regulatory standards at 3 m from interfering sources, should not cause much effect. Other interference can arise from modulation of a strong RF signal by mains frequency power components in the Doppler equipment and from associated computer circuits. These require careful layout to reduce electric and magnetic coupling, decoupling and filtering of power supplies and components, screening of RF circuits and particular attention to the reduction of power and computer signal currents flowing in RF signal earth paths. Finally, some initial simple acceptance tests for interference susceptibility are proposed, based on the application of 300 microV of RF signal between transducer body and equipment enclosure and 10 mV to the mains supply.

Follett DH

1991-11-01

248

Doppler study of cerebral arteries in hypercholesterolemia  

Directory of Open Access Journals (Sweden)

Full Text Available Mehdi Farhoudi1, Kaveh Mehrvar2, Naser Aslanabadi3, Kamyar Ghabili1, Nazila Rasi Baghmishe4, Farzad Ilkhchoei41Neuroscience Research Center, 2Razi Hospital, 3Department of Cardiology, 4Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, IranBackground: Hypercholesterolemia is one of the major modifiable risk factors for atherosclerosis of the coronary and carotid arteries. Although transcranial Doppler (TCD) studies of the cerebral arteries are indicative of decreased cerebral blood flow velocities in patients with hypercholesterolemia, the number of these studies has been limited. The aim of this study was to assess the hemodynamic status of the cerebral arteries in patients with hypercholesterolemia using TCD.Methods: In a case-control study, 60 individuals, including 30 hypercholesterolemic cases (low-density lipoprotein [LDL] > 160 mg/dL) and 30 healthy controls were enrolled. Other arterial risk factors, including diabetes mellitus, hypertension, smoking, and obesity (body mass index > 30), were evaluated and matched as well. TCD was used to assess the hemodynamics of the intracranial arteries as well as the internal carotid arteries. The mean blood flow velocity, pulsatility index, and resistance index were recorded in all the arteries.Results: The mean blood flow velocity, pulsatility index, and resistance index of the intracranial arteries and internal carotid arteries were not significantly different between the two groups (P > 0.05). However, those with higher levels of LDL (>180 mg/dL) showed significantly lower mean blood flow velocity and resistance index of the internal carotid arteries than the healthy controls. In addition, individuals with high-density lipoprotein (HDL) <35 mg/dL had significantly lower mean blood flow velocity in the internal carotid arteries.Conclusion: Hypercholesterolemia (LDL > 160 mg/dL) does not seem to have a detrimental effect on the hemodynamic status of the intracranial arteries and internal carotid arteries. However, in cases of higher LDL (>180 mg/dL) and lower HDL, decreased TCD parameters in the internal carotid arteries, as a surrogate of the peripheral arteries, are prominent.Keywords: hypercholesterolemia, transcranial Doppler, cerebral arteries

Farhoudi M; Mehrvar K; Aslanabadi N; Ghabili K; Baghmishe NR; Ilkhchoei F

2011-01-01

249

Experimental observation of rotational Doppler broadening in a molecular system.  

UK PubMed Central (United Kingdom)

The first experimental evidence of rotational Doppler broadening in photoelectron spectra, reported here, show good agreement with recently described theoretical predictions. The dependence of the broadening on temperature and photoelectron kinetic energy is quantitatively predicted by the theory. The experiments verify that the rotational contributions to the linewidth are comparable to those from translational Doppler broadening and must be considered in the analysis of high-resolution photoelectron spectra. A classical model accounting for this newly observed effect is presented.

Thomas TD; Kukk E; Ueda K; Ouchi T; Sakai K; Carroll TX; Nicolas C; Travnikova O; Miron C

2011-05-01

250

Experimental Observation of Rotational Doppler Broadening in a Molecular System  

Science.gov (United States)

The first experimental evidence of rotational Doppler broadening in photoelectron spectra, reported here, show good agreement with recently described theoretical predictions. The dependence of the broadening on temperature and photoelectron kinetic energy is quantitatively predicted by the theory. The experiments verify that the rotational contributions to the linewidth are comparable to those from translational Doppler broadening and must be considered in the analysis of high-resolution photoelectron spectra. A classical model accounting for this newly observed effect is presented.

Thomas, T. D.; Kukk, E.; Ueda, K.; Ouchi, T.; Sakai, K.; Carroll, T. X.; Nicolas, C.; Travnikova, O.; Miron, C.

2011-05-01

251

Transthoracic Doppler echocardiography of the left internal mammary artery graft.  

UK PubMed Central (United Kingdom)

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.

Pârv A; Ober C; Bindea D; Duncea C

2013-03-01

252

Measurement of Water Flowing Velocity Using Laser Doppler Velocimetry Technique  

International Nuclear Information System (INIS)

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

2005-01-01

253

Doppler-insensitive differential excitation of isotopic atoms  

Energy Technology Data Exchange (ETDEWEB)

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

Pegg, D.T. (Imperial Coll. of Science and Technology, London (UK). Blackett Lab.)

1981-05-28

254

Doppler-insensitive differential excitation of isotopic atoms  

International Nuclear Information System (INIS)

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

1981-01-01

255

Transcranial Doppler ultrasound and cerebral angiography - alternative or complementary  

Energy Technology Data Exchange (ETDEWEB)

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.

Bockenheimer, S.; Lorey, N.

1985-11-01

256

Transcranial Doppler ultrasound and cerebral angiography - alternative or complementary  

International Nuclear Information System (INIS)

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

1985-01-01

257

[Transesophageal echocardiography (Part 2): Basic concepts in Doppler techniques  

UK PubMed Central (United Kingdom)

Cardiac Doppler techniques provide information on blood flow dynamics by applying Doppler frequency shift analysis to echo signals from moving red blood cells. Velocity and direction of blood flow can be determined and instantaneously displayed on a monitor screen. These techniques include pulsed-wave Doppler (PWD), continuous wave Doppler (CWD) and color Doppler imaging (CDI). In PWD, short bursts of ultrasound waves are emitted at a pulse-repetition frequency (PRF), and velocity and direction of blood flow can be measured at specific locations in the heart. This technique enables measurement with high spatial resolution. By its nature as a sampling system, however, PWD can not accurately measure Doppler shift frequency exceeding the Nyquist limit (PRF/2). In CWD, ultrasound pulses are continuously emitted and received by two separate transducers. Precise localization of a sampling volume is impossible in this technique, but CWD can determine higher flow velocity without ambiguity than that detected by PWD. CWD is useful to evaluate high-velocity blood flows such as those seen with valvular diseases or shunt lesions. CDI displays two-dimensional patterns of blood flow in colors, superimposed on the two-dimensional images of the heart structures. Thus, the velocity, direction and location of blood flows can be visualized in real-time. This technique facilitates detection of abnormal blood flows in the heart and major blood vessels, and it is also utilized to evaluate the severity of valvular regurgitation.

Hayashi H; Kumon K

1996-07-01

258

[Transesophageal echocardiography (Part 2): Basic concepts in Doppler techniques].  

Science.gov (United States)

Cardiac Doppler techniques provide information on blood flow dynamics by applying Doppler frequency shift analysis to echo signals from moving red blood cells. Velocity and direction of blood flow can be determined and instantaneously displayed on a monitor screen. These techniques include pulsed-wave Doppler (PWD), continuous wave Doppler (CWD) and color Doppler imaging (CDI). In PWD, short bursts of ultrasound waves are emitted at a pulse-repetition frequency (PRF), and velocity and direction of blood flow can be measured at specific locations in the heart. This technique enables measurement with high spatial resolution. By its nature as a sampling system, however, PWD can not accurately measure Doppler shift frequency exceeding the Nyquist limit (PRF/2). In CWD, ultrasound pulses are continuously emitted and received by two separate transducers. Precise localization of a sampling volume is impossible in this technique, but CWD can determine higher flow velocity without ambiguity than that detected by PWD. CWD is useful to evaluate high-velocity blood flows such as those seen with valvular diseases or shunt lesions. CDI displays two-dimensional patterns of blood flow in colors, superimposed on the two-dimensional images of the heart structures. Thus, the velocity, direction and location of blood flows can be visualized in real-time. This technique facilitates detection of abnormal blood flows in the heart and major blood vessels, and it is also utilized to evaluate the severity of valvular regurgitation. PMID:8741476

Hayashi, H; Kumon, K

1996-07-01

259

Doppler velocity measurements from large and small arteries of mice.  

UK PubMed Central (United Kingdom)

With the growth of genetic engineering, mice have become increasingly common as models of human diseases, and this has stimulated the development of techniques to assess the murine cardiovascular system. Our group has developed nonimaging and dedicated Doppler techniques for measuring blood velocity in the large and small peripheral arteries of anesthetized mice. We translated technology originally designed for human vessels for use in smaller mouse vessels at higher heart rates by using higher ultrasonic frequencies, smaller transducers, and higher-speed signal processing. With these methods one can measure cardiac filling and ejection velocities, velocity pulse arrival times for determining pulse wave velocity, peripheral blood velocity and vessel wall motion waveforms, jet velocities for the calculation of the pressure drop across stenoses, and left main coronary velocity for the estimation of coronary flow reserve. These noninvasive methods are convenient and easy to apply, but care must be taken in interpreting measurements due to Doppler sample volume size and angle of incidence. Doppler methods have been used to characterize and evaluate numerous cardiovascular phenotypes in mice and have been particularly useful in evaluating the cardiac and vascular remodeling that occur following transverse aortic constriction. Although duplex ultrasonic echo-Doppler instruments are being applied to mice, dedicated Doppler systems are more suitable for some applications. The magnitudes and waveforms of blood velocities from both cardiac and peripheral sites are similar in mice and humans, such that much of what is learned using Doppler technology in mice may be translated back to humans.

Hartley CJ; Reddy AK; Madala S; Entman ML; Michael LH; Taffet GE

2011-08-01

260

Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking  

Directory of Open Access Journals (Sweden)

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

Armstrong J. W.

2006-01-01

 
 
 
 
261

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-07-01

262

Transcranial duplex doppler ultrasonography in dogs with hydrocephalus/ Ultrassonografia duplex Doppler transcraniana em cães com hidrocefalia  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Foi realizada a ultrassonografia duplex Doppler transcraniana em 32 cães, conscientes, que apresentavam ventriculomegalia previamente detectada ao exame modo-B, para obter as medidas dos ventrículos laterais e os parâmetros de resistência das artérias cerebrais antes e depois de 30 dias de tratamento clínico. Os animais foram distribuídos em dois grupos: 1 - formado por cães que apresentaram remissão ou diminuição dos sinais clínicos após tratamento; 2 - por (more) cães que apresentaram piora dos sinais neurológicos ou estabilidade do quadro clínico. Todos os dados foram dispostos em tabelas e submetidos ao teste t pareado e a modelos de regressão logística para avaliar a influência da redução do índice de resistividade (IR). Não foi observada influência das variáveis em modo-B. Após o tratamento, a média do IR foi significantemente menor para o grupo que apresentou melhora clínica; não houve diferença significativa da média de redução do IR para a mesma artéria quando comparados os lados direito e esquerdo. Concluiu-se que o duplex Doppler transcraniano é um métodos de avaliação hemodinâmica capaz de monitorar mais precisamente o tratamento da hidrocefalia em cães e verificar a resposta dos pacientes. Abstract in english Transcranial duplex Doppler ultrasound was performed in 32 conscious dogs presenting ventriculomegaly detected in B-mode, obtaining measures of lateral ventricles and resistance parameters of main cerebral arteries before and after 30 days of clinical treatment. The animals were distributed divided in two groups: group 1, dogs that presented remission or decrease of the neurological signs of the disease after clinical therapy; and group 2, dogs that displayed worsening of (more) the neurological signs or clinical stability. The data were all presented in tables and were submitted to paired t test and to logistic regression models to evaluate the influence of the RI reduction on both groups. There was no significant influence of the variables in the B-mode. After the treatment, the mean resistive index (RI) was significantly lower for the group that presented clinical improvement. There was no significant difference of the mean RI reduction for the same artery when the right and left sides were compared. It could be concluded that transcranial duplex Doppler ultrasound is a method of cerebral hemodynamic assessment able to monitor more precisely the treatment of hydrocephalus in dogs and verify the responses.

Carvalho, C.F.; Chammas, M.C.; Andrade Neto, J.P.; Jimenez, C.D.; Diniz, S.A.; Cerri, G.G.

2010-02-01

263

Transcranial duplex doppler ultrasonography in dogs with hydrocephalus Ultrassonografia duplex Doppler transcraniana em cães com hidrocefalia  

Directory of Open Access Journals (Sweden)

Full Text Available Transcranial duplex Doppler ultrasound was performed in 32 conscious dogs presenting ventriculomegaly detected in B-mode, obtaining measures of lateral ventricles and resistance parameters of main cerebral arteries before and after 30 days of clinical treatment. The animals were distributed divided in two groups: group 1, dogs that presented remission or decrease of the neurological signs of the disease after clinical therapy; and group 2, dogs that displayed worsening of the neurological signs or clinical stability. The data were all presented in tables and were submitted to paired t test and to logistic regression models to evaluate the influence of the RI reduction on both groups. There was no significant influence of the variables in the B-mode. After the treatment, the mean resistive index (RI) was significantly lower for the group that presented clinical improvement. There was no significant difference of the mean RI reduction for the same artery when the right and left sides were compared. It could be concluded that transcranial duplex Doppler ultrasound is a method of cerebral hemodynamic assessment able to monitor more precisely the treatment of hydrocephalus in dogs and verify the responses.Foi realizada a ultrassonografia duplex Doppler transcraniana em 32 cães, conscientes, que apresentavam ventriculomegalia previamente detectada ao exame modo-B, para obter as medidas dos ventrículos laterais e os parâmetros de resistência das artérias cerebrais antes e depois de 30 dias de tratamento clínico. Os animais foram distribuídos em dois grupos: 1 - formado por cães que apresentaram remissão ou diminuição dos sinais clínicos após tratamento; 2 - por cães que apresentaram piora dos sinais neurológicos ou estabilidade do quadro clínico. Todos os dados foram dispostos em tabelas e submetidos ao teste t pareado e a modelos de regressão logística para avaliar a influência da redução do índice de resistividade (IR). Não foi observada influência das variáveis em modo-B. Após o tratamento, a média do IR foi significantemente menor para o grupo que apresentou melhora clínica; não houve diferença significativa da média de redução do IR para a mesma artéria quando comparados os lados direito e esquerdo. Concluiu-se que o duplex Doppler transcraniano é um métodos de avaliação hemodinâmica capaz de monitorar mais precisamente o tratamento da hidrocefalia em cães e verificar a resposta dos pacientes.

C.F. Carvalho; M.C. Chammas; J.P. Andrade Neto; C.D. Jimenez; S.A. Diniz; G.G. Cerri

2010-01-01

264

Image-based tracking laser Doppler vibrometer  

International Nuclear Information System (INIS)

An innovative version of the tracking laser Doppler vibrometer based on image acquisition and processing (iTLDV) is proposed. The iTLDV is developed for tracking of arbitrary motions; the system is feedback controlled and allows measuring the vibrations of a moving target by driving moving mirrors via position signals of the target obtained from a charge-coupled-device camera and an image processing algorithm. The tracking system developed has been applied to an industrial test case subject to self-excited vibrations, in order to verify the performances and limits in the operating conditions. The system demonstrates its ability to measure vibration time histories on a windscreen wiper in operative conditions. This test case represents a challenging measurement problem, since no other measurement techniques are available that are able to extract such data. Some examples of obtained data are shown, which highlight the potential of iTLDV. In addition, position accuracy and measurement uncertainty are discussed. For the windscreen wiper, the worst position accuracy is estimate as ±1.2 mm along the wiper axis, while the measurement uncertainty mainly depends on the commercial vibrometer applied in the setup (about ±2% depending on operative conditions)

2004-01-01

265

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

266

Doppler Pulsatility Index in Spontaneous Intracerebral Hemorrhage.  

UK PubMed Central (United Kingdom)

Background and Purpose: Elevated intracranial pressure (ICP) as a result of intracerebral hemorrhage (ICH) and perihematomal edema often leads to tissue shift, which can be identified in cross-sectional imaging and presents a known predictor of functional outcome. Pulsatility indices (PIs) of the intracranial arteries as measured by transcranial Doppler sonography (TCD) may serve as surrogate parameters for ICP. This study aims to investigate whether PI correlates with ICP and midline shift and serves as a reliable predictor of functional outcome in patients with ICH. Methods: Within a 1-year period between April 2009 and April 2010, 136 patients with acute spontaneous, supratentorial ICH were admitted to our tertiary care hospital. One-hundred and twenty-four patients fulfilled the inclusion criteria and were eligible for analysis. TCD and transcranial duplex sonography were performed on admission and at least once more during hospital stay. Functional outcome was assessed 6 months after discharge. Correlation analyses, logistic regression analyses and receiver operating characteristic curves were calculated. Results: One-hundred and twenty-four patients were included in the analysis. Six-month mortality amounted to 39.5%. The ICH score and PIs of the middle cerebral artery were independent predictors of outcome 6 months after discharge. Conclusions: Early PI monitoring by TCD correlated with ICP and may be used to predict the outcome after 6 months.

Kiphuth IC; Huttner HB; Dörfler A; Schwab S; Köhrmann M

2013-07-01

267

Laser Doppler echo signal detection method  

Science.gov (United States)

The coherent lidar system for speed measurement and the characteristics of the echo signal are discussed. And the principle and the advantages of the digital quadrature transform are analyzed. A digital quadrature detection scheme based on polyphase filter for coherent lidar system for speed measurement is presented by using the idea of software radio. Firstly the amplified analog signal is sampled to digital signal, and then is re-sampled with parity, time-aligned by delay filtering, finally the signal is divided into in-phase component and quadrature component. The scheme can be used to decrease the hardware complexity of system to a large extent, to avoid aliasing between the positive and the negative spectrums, to improve the SNR, and to obtain the signal in the quadrature form so as to fit the follow-up processing. Simulations and experiments indicate that the scheme is capable of resisting the noise compared with the traditional methods and is prone to real-time implementation, which, in turn, makes a contribution to greatly improve the performance of coherent Doppler lidar system for speed measurement and to orient the direction of a moving target.

Wang, Jiqiang; Zhang, Chunxi; Feng, Di; Ou, Pan; Tian, Lun

2009-05-01

268

A prospective analysis of free flap monitoring techniques: physical examination, external Doppler, implantable Doppler, and tissue oximetry.  

UK PubMed Central (United Kingdom)

No universally accepted method of flap monitoring exists, and several techniques are in use. Repeated physical examination is most popular and is often supplemented with a handheld, external Doppler, and/or implantable Doppler probes; near-infrared spectroscopy is less commonly used. We investigated the nursing and resident house staff's experience and confidence with physical exam for flap monitoring. Also, a consecutive series of 38 patients with free flaps were monitored using physical examination, external Doppler, implantable arterial and venous Doppler probes, and near-infrared spectroscopy. Five patients developed signs of microvascular complications within 3 days of surgery; all were explored and salvaged. Neither the residents nor the nursing staff were universally trained or experienced in flap monitoring by physical exam. In all patients, changes in the appearance of the flap suggestive of a microvascular complication lagged 30 to 60 minutes after the adjunctive monitoring methods indicated that a problem had occurred. Near-infrared spectroscopy was the first warning sign in four of the five patients. Two patients were explored before thrombosis of the anastomoses occurred. Near-infrared spectroscopy may identify early microvascular complications more reliably than physical examination, external Doppler, or implantable Doppler.

Lohman RF; Langevin CJ; Bozkurt M; Kundu N; Djohan R

2013-01-01

269

Three-dimensional power Doppler transanal ultrasonography, to monitor haemorrhoidal blood flow after Doppler-guided ALTA sclerosing therapy.  

UK PubMed Central (United Kingdom)

AIM: The study aimed to use power Doppler imaging (PDI) transanal ultrasonography to produce three-dimensional power Doppler angiography images of haemorrhoidal tissue and to monitor the effects of Doppler-guided aluminium potassium sulfate and tannic acid (DGALTA) sclerotherapy. METHOD: Ninety-six haemorrhoids in 43 patients were examined using PDI transanal ultrasonography, and DGALTA sclerotherapy was performed from April 2011 to April 2012. DGALTA sclerotherapy was conducted using a four-step injection process with pulse wave Doppler ultrasound under perianal local anaesthesia. RESULTS: A three-dimensional power Doppler angiography image of the blood flow in haemorrhoidal tissue was produced using PDI transanal ultrasonography. The cross-sectional area of blood flow in the haemorrhoidal tissue (PDI area) significantly decreased after DGALTA sclerotherapy. The PDI areas in the preoperative state and 1 and 3 months after treatment were 0.35±0.27, 0.03±0.05 and 0.04±0.05 cm(2) (P<0.0001). CONCLUSION: A three-dimensional power Doppler angiography image of the haemorrhoidal tissue was technically possible and showed blood flow in the haemorrhoidal tissue to be significantly decreased after DGALTA sclerotherapy.

Miyamoto H; Asanoma M; Miyamoto H; Takasu C; Shimada M

2013-02-01

270

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

Directory of Open Access Journals (Sweden)

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

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

2006-01-01

271

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

Scientific Electronic Library Online (English)

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

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

2006-06-01

272

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

Directory of Open Access Journals (Sweden)

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

Thomas George

2004-01-01

273

Tissue Doppler echocardiography - a case of right tool, wrong use.  

UK PubMed Central (United Kingdom)

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 G

2004-01-01

274

ADEPT - Abnormal Doppler Enteral Prescription Trial  

Directory of Open Access Journals (Sweden)

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

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

2009-01-01

275

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

Science.gov (United States)

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

Fung, Edward K.; Carson, Richard E.

2013-03-01

276

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

International Nuclear Information System (INIS)

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

2013-03-21

277

Laser Doppler velocimetry and fluorescein dye in the prediction of skin flap viability. A comparison.  

UK PubMed Central (United Kingdom)

Laser Doppler velocimetry provides a quantitative and noninvasive measurement of cutaneous blood flow. Piglets were used to compare laser Doppler velocimetry and fluorescein with each other and as predictors of flap viability. Twenty-five random pattern rectangular skin flaps were studied with both techniques. Eighteen of the flaps were observed for two weeks and the length of viable flap documented. A reading of 100 mV on the laser Doppler corresponded with full fluorescence after dye injection. Both fluorescein and the laser Doppler underestimated flap surviving length slightly. Laser Doppler readings taken 24 hours postoperatively predicted the length of surviving flap exactly. The laser Doppler correlated well with fluorescein dye.

Larrabee WF Jr; Sutton GD; Holloway A Jr; Tolentino G

1983-07-01

278

Acute intrascrotal pathology in childhood: color Doppler study  

International Nuclear Information System (INIS)

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

1997-01-01

279

Early Doppler-echocardiography evaluation of 597 prosthetic aortic valves.  

UK PubMed Central (United Kingdom)

OBJECTIVES: This study was designed to describe the Doppler-echocardiography normal values in the early postoperative phase for Carpentier-Edwards Perimount Aortic Heart Valve bioprosthesis (CEP), St. Jude Medical (SJM) or Medical Regent (SJMR) Mechanical Heart Valves, evaluated by a single experienced echo-laboratory. METHODS: Five hundred and ninety-seven consecutive patients in our hospital, who had had a CEP, a SJM or SJMR-17 mm implanted due to aortic stenosis, underwent a control Doppler-echocardiography evaluation 4-7 days after surgery. Hemodynamic performance of SJM, SJMR and CEP were accurately described, evaluating flow-dependent (trans-prosthetic velocities and gradients) and flow-independent (effective orifice area, indexed effective orifice area and Doppler velocity index) Doppler-echocardiography parameters. RESULTS: Of the 597 patients 50.6% were women (n = 302). Mean age was 66.3 +/- 11.7 years. Mean body surface area (BSA) was 1.76 +/- 0.22 m. Mean ejection fraction was 55.3 +/- 10.3%. Two hundred and sixty CEPs and 337 St. Jude mechanical valves (301 SJM and 36 SJMR size-17) were implanted. Comparing size-by-size SJM to CEP, the former were basically less flow obstructive. CONCLUSION: Our data confirm the wide range of variability, pointing out the need to perform routinely an accurate baseline Doppler-echocardiography evaluation of the hemodynamic profile of prosthetic aortic valves, including flow-dependent and independent parameters, to allow an adequate interpretation at follow-up.

Minardi G; Pino PG; Manzara CC; Pulignano G; Viceconte GN; Stefanini GG; Gaudio C; Musumeci F

2010-04-01

280

Renal power Doppler ultrasonographic evaluation of children with acute pyelonephritis.  

Science.gov (United States)

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. PMID:22071640

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

2011-01-01

 
 
 
 
281

A study of doppler waveform using pulsatile flow model  

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-08-01

282

Renal power Doppler ultrasonographic evaluation of children with acute pyelonephritis.  

UK PubMed Central (United Kingdom)

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.

Shajari A; Nafisi-Moghadam R; Malek M; Smaili A; Fallah M; Pahlusi A

2011-01-01

283

Doppler US evaluation of renal biopsy complications in children.  

UK PubMed Central (United Kingdom)

PURPOSE: Percutaneous renal biopsy plays an important role in the diagnosis and management of renal disease in children, but it does carry some complications. As most cases are vascular in origin, Doppler ultrasonography (US) has clear benefits in terms of detecting bleeding and assessing vascular damage. The aim of this study was to investigate the effectiveness of Doppler US in detecting possible complications after percutaneous renal biopsy in pediatric patients. MATERIALS AND METHODS: This retrospective study was performed using the data obtained from all pediatric patients who underwent renal biopsy in our institution between 1999 and 2011. RESULTS: A total of 175 biopsies were performed in 172 patients (48.3% male, 51.7% female) ranging in age from 1 to 17 years (mean, 8.7 years). Of 175 biopsies, 42 (24.0%) led to complications. Overall, 52 complications (25% major, 75% minor) occurred following 42 biopsies. CONCLUSION: Doppler US examination is capable of and helpful in detecting possible vascular complications such as pseudoaneurysm and arteriovenous fistula and improves the management of these patients after biopsy. It is important to recognize the Doppler US appearance of complications associated with percutaneous renal biopsy and to perform close follow-up with Doppler US in the first 24 hours.

Gülcü A; Göktay Y; Soylu A; Türkmen M; Kavukçu S; Seçil M; Karabay N

2013-01-01

284

Blood flow measurement by laser Doppler method in orofacial region  

Directory of Open Access Journals (Sweden)

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

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

2010-01-01

285

Doppler effect in the oscillator radiation process in the medium  

International Nuclear Information System (INIS)

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

2011-01-01

286

Reproducibility of intravascular ultrasound and intracoronary Doppler measurements.  

UK PubMed Central (United Kingdom)

The aim of this study was to evaluate the reproducibility of intravascular ultrasound (IVUS) and intracoronary (IC) Doppler flow velocity measurements. The use of IVUS and IC Doppler has been suggested as a means for percutaneous coronary intervention (PCI) guidance in a series of studies. This would require an acceptable level of accuracy and reproducibility of these two methods for lesion evaluation. In this study, the main focus was on the issue of reproducibility. One hundred and eight patients referred for PCI entered into the study. Inter- and intraobserver variability was measured. Catheter difference was assessed. On-line and off-line measurements were compared. MUSIC criteria were assessed off-line, twice. Calculated and measured diameters were compared. After having obtained initial IC Doppler measurements, the Doppler wire was immediately withdrawn and repositioned for reacquisition of Doppler measurements. IVUS measurements are reproducible and reliable off-line and, to a slightly lesser degree, on-line. Area measurements should be performed more than once and the mean used for vessel description. Lumen diameters should be calculated from the mean of the area measurements. A measuring technique consensus should be reached and adhered to. CFR measurements can be used to determine reduced vs. normal flow reserve. In this study, it was found that proximal to distal velocity ratio and diastolic to systolic velocity ratio variability made these parameters unsuitable for PCI guidance.

Gaster AL; Korsholm L; Thayssen P; Pedersen KE; Haghfelt TH

2001-08-01

287

[Musical murmurs: phonocardiographic, echocardiographic and Doppler echocardiographic study].  

Science.gov (United States)

Musical murmurs are probably related to the vibrations of some structures in the cardiovascular system, and this may be reflected in the characteristic stripes which are recorded by the fast Fourier transformation (FFT) of the pulsed Doppler echocardiography (so-called FFT stripe). In the present study, we demonstrated new stripes by color Doppler echocardiography, which were composed of multiple warm and cold color bands which we termed color Doppler stripes (CD stripe). An experiment was performed to obtain Doppler signals from the surface of a vibrating tonometer at a frequency of 128 Hz. When the CD stripe was obtained, a similar FFT stripe was also recorded from the same sampling site. Fourteen patients with musical murmurs were selected from 2,000 consecutive phonocardiographic records made during the last one and a half years. The CD stripe was obtained in three and the FFT stripe in six. When both stripes were obtained, the FFT stripe was always obtained if we set carefully the sample site in the CD stripe, and these two were consistent in timing. We concluded that, in view of the close correlation between the CD stripe and the FFT stripe, the newly observed CD stripe is also a characteristic finding reflecting a regularly vibrating structure. The technical feasibility of color Doppler echocardiography to detect fine movements of structures may be helpful in the study of musical murmurs. PMID:3655420

Suzuki, J; Sakamoto, T; Hada, Y; Amano, K; Takahashi, H; Hasegawa, I; Takahashi, T; Sugimoto, T

1986-09-01

288

[Musical murmurs: phonocardiographic, echocardiographic and Doppler echocardiographic study  

UK PubMed Central (United Kingdom)

Musical murmurs are probably related to the vibrations of some structures in the cardiovascular system, and this may be reflected in the characteristic stripes which are recorded by the fast Fourier transformation (FFT) of the pulsed Doppler echocardiography (so-called FFT stripe). In the present study, we demonstrated new stripes by color Doppler echocardiography, which were composed of multiple warm and cold color bands which we termed color Doppler stripes (CD stripe). An experiment was performed to obtain Doppler signals from the surface of a vibrating tonometer at a frequency of 128 Hz. When the CD stripe was obtained, a similar FFT stripe was also recorded from the same sampling site. Fourteen patients with musical murmurs were selected from 2,000 consecutive phonocardiographic records made during the last one and a half years. The CD stripe was obtained in three and the FFT stripe in six. When both stripes were obtained, the FFT stripe was always obtained if we set carefully the sample site in the CD stripe, and these two were consistent in timing. We concluded that, in view of the close correlation between the CD stripe and the FFT stripe, the newly observed CD stripe is also a characteristic finding reflecting a regularly vibrating structure. The technical feasibility of color Doppler echocardiography to detect fine movements of structures may be helpful in the study of musical murmurs.

Suzuki J; Sakamoto T; Hada Y; Amano K; Takahashi H; Hasegawa I; Takahashi T; Sugimoto T

1986-09-01

289

Thyroid ultrasonography B-mode and color-Doppler.  

Science.gov (United States)

Recently, ultrasonography of the thyroid gland has proved to be a useful clinical diagnostic method. The newly developed high-resolution ultrasonography with color-Doppler flow mapping function can reveal fine details of the thyroid gland and the hemodynamic features of thyroid neoplasmas. Ultrasonography can deliver a diagnostic accuracy of over 90% in thyroid carcinoma, especially papillary carcinoma. However, in the case of follicular carcinoma, neither conventional B-mode ultrasound imaging nor aspiration biopsy cytology can deliver satisfactory results. Color-Doppler imaging examination of 212 follicular tumors has been carried out, resulting in the characteristic finding that a high-velocity pulsative blood flow penetrates the tumor in the case of follicular carcinoma, which led to new diagnostic criteria with color-Doppler examination. The differential diagnostic grading score using color-Doppler examination and FFT analysis can show a dramatic diagnostic accuracy of 81.0%, a sensitivity of 88.9% and a specificity of 74.2%. Ultrasound with the color-Doppler function can play a more important role in the differential diagnosis of thyroid tumors. PMID:12487253

Fukunari, Nobuhiro

2002-01-01

290

Thyroid ultrasonography B-mode and color-Doppler.  

UK PubMed Central (United Kingdom)

Recently, ultrasonography of the thyroid gland has proved to be a useful clinical diagnostic method. The newly developed high-resolution ultrasonography with color-Doppler flow mapping function can reveal fine details of the thyroid gland and the hemodynamic features of thyroid neoplasmas. Ultrasonography can deliver a diagnostic accuracy of over 90% in thyroid carcinoma, especially papillary carcinoma. However, in the case of follicular carcinoma, neither conventional B-mode ultrasound imaging nor aspiration biopsy cytology can deliver satisfactory results. Color-Doppler imaging examination of 212 follicular tumors has been carried out, resulting in the characteristic finding that a high-velocity pulsative blood flow penetrates the tumor in the case of follicular carcinoma, which led to new diagnostic criteria with color-Doppler examination. The differential diagnostic grading score using color-Doppler examination and FFT analysis can show a dramatic diagnostic accuracy of 81.0%, a sensitivity of 88.9% and a specificity of 74.2%. Ultrasound with the color-Doppler function can play a more important role in the differential diagnosis of thyroid tumors.

Fukunari N

2002-01-01

291

Doppler transcraniano na prática neurológica/ Transcranial Doppler in the neurological practice  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O Doppler transcraniano (DTC) é um método relativamente novo, descrito em 1982 por Rune Aaslid e introduzido no Brasil em 1992 por Roberto Hirsch, na Universidade de São Paulo. O serviço de Neurologia do Hospital de Clínicas da Universidade Federal do Paraná (HC-UFPR) disponibilizou esse exame em 2001, com divulgação das principais vantagens do método no diagnóstico, seguimento e manejo terapêutico de pacientes com suspeita ou portadores de doença cerebrovascu (more) lar. O objetivo deste trabalho é demonstrar como o DTC vem sendo utilizado em nosso meio e quais são as especialidades médicas que vêm absorvendo o auxílio do método. Embora diretrizes como a publicada pela Academia Americana de Neurologia em 2004 validem as indicações do DTC, estabelecendo especificidade e sensibilidade do método, verificamos que a solicitação do exame em nosso meio depende da divulgação do serviço, da implementação de linhas de pesquisa e, finalmente, do reconhecimento de sua utilidade na prática diária. Abstract in english Transcranial Doppler (TCD) was described in 1982 by Rune Aaslid and introduced in Brazil in 1992 by Roberto Hirsh in the University of São Paulo. Since the acquisition of TCD by Neurology Division of Hospital de Clínicas of Universidade Federal do Paraná (HC-UFPR) in 2001, the knowledge about TCD clinical utility has been increasing for diagnosis, follow-up and management of patients with cerebrovascular diseases. The objective of this study is to describe the current (more) TCD indications and medical specialties indicators in our hospital. Although guidelines as published by the American Academy of Neurology establish values for TCD study with method?s specificity and sensibility, we realize that the utility in our center depends on our efforts to show method?s beneficial in various clinical settings.

Zétola, Viviane Flumignan; Lange, Marcos Christiano; Muzzio, Juliano A.; Marchioro, Ivo; Nóvak, Edison Mattos; Werneck, Lineu C.

2006-03-01

292

Doppler transcraniano na prática neurológica Transcranial Doppler in the neurological practice  

Directory of Open Access Journals (Sweden)

Full Text Available O Doppler transcraniano (DTC) é um método relativamente novo, descrito em 1982 por Rune Aaslid e introduzido no Brasil em 1992 por Roberto Hirsch, na Universidade de São Paulo. O serviço de Neurologia do Hospital de Clínicas da Universidade Federal do Paraná (HC-UFPR) disponibilizou esse exame em 2001, com divulgação das principais vantagens do método no diagnóstico, seguimento e manejo terapêutico de pacientes com suspeita ou portadores de doença cerebrovascular. O objetivo deste trabalho é demonstrar como o DTC vem sendo utilizado em nosso meio e quais são as especialidades médicas que vêm absorvendo o auxílio do método. Embora diretrizes como a publicada pela Academia Americana de Neurologia em 2004 validem as indicações do DTC, estabelecendo especificidade e sensibilidade do método, verificamos que a solicitação do exame em nosso meio depende da divulgação do serviço, da implementação de linhas de pesquisa e, finalmente, do reconhecimento de sua utilidade na prática diária.Transcranial Doppler (TCD) was described in 1982 by Rune Aaslid and introduced in Brazil in 1992 by Roberto Hirsh in the University of São Paulo. Since the acquisition of TCD by Neurology Division of Hospital de Clínicas of Universidade Federal do Paraná (HC-UFPR) in 2001, the knowledge about TCD clinical utility has been increasing for diagnosis, follow-up and management of patients with cerebrovascular diseases. The objective of this study is to describe the current TCD indications and medical specialties indicators in our hospital. Although guidelines as published by the American Academy of Neurology establish values for TCD study with method’s specificity and sensibility, we realize that the utility in our center depends on our efforts to show method’s beneficial in various clinical settings.

Viviane Flumignan Zétola; Marcos Christiano Lange; Juliano A. Muzzio; Ivo Marchioro; Edison Mattos Nóvak; Lineu C. Werneck

2006-01-01

293

Pulse inversion Doppler: a new method for detecting nonlinear echoes from microbubble contrast agents.  

UK PubMed Central (United Kingdom)

A novel technique for the selective detection of ultrasound contrast agents, called pulse inversion Doppler, has been developed. In this technique, a conventional Doppler or color Doppler pulse sequence is modified by inverting every second transmit pulse. Either conventional or harmonic Doppler processing is then performed on the received echoes. In the resulting Doppler spectra, Doppler shifts from linear and nonlinear scattering are separated into two distinct regions that can be analyzed separately or combined to estimate the ratio of nonlinear to linear scattering from a region of tissue. The maximum Doppler shift that can be detected is 1/2 the normal Nyquist limit. This has the advantage over conventional harmonic Doppler that it can function over the entire bandwidth of the echo signal, thus achieving superior spatial resolution in the Doppler image. In vitro measurements comparing flowing agent and cellulose particles suggest that pulse inversion Doppler can provide 3 to 10 dB more agent to tissue contrast than harmonic imaging with similar pulses. Similar measurements suggest that broadband pulse inversion Doppler can provide up to 16 dB more contrast than broadband conventional Doppler. Nonlinear propagation effects limit the maximum contrast obtainable with both harmonic and pulse inversion Doppler techniques.

Simpson DH; Chin CT; Burns PN

1999-01-01

294

Pulse inversion Doppler: a new method for detecting nonlinear echoes from microbubble contrast agents.  

Science.gov (United States)

A novel technique for the selective detection of ultrasound contrast agents, called pulse inversion Doppler, has been developed. In this technique, a conventional Doppler or color Doppler pulse sequence is modified by inverting every second transmit pulse. Either conventional or harmonic Doppler processing is then performed on the received echoes. In the resulting Doppler spectra, Doppler shifts from linear and nonlinear scattering are separated into two distinct regions that can be analyzed separately or combined to estimate the ratio of nonlinear to linear scattering from a region of tissue. The maximum Doppler shift that can be detected is 1/2 the normal Nyquist limit. This has the advantage over conventional harmonic Doppler that it can function over the entire bandwidth of the echo signal, thus achieving superior spatial resolution in the Doppler image. In vitro measurements comparing flowing agent and cellulose particles suggest that pulse inversion Doppler can provide 3 to 10 dB more agent to tissue contrast than harmonic imaging with similar pulses. Similar measurements suggest that broadband pulse inversion Doppler can provide up to 16 dB more contrast than broadband conventional Doppler. Nonlinear propagation effects limit the maximum contrast obtainable with both harmonic and pulse inversion Doppler techniques. PMID:18238434

Simpson, D H; Chin, C T; Burns, P N

1999-01-01

295

The Doppler paradigm and the APEX-EPOS-ORANGE quandary  

CERN Multimedia

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

Griffin, J J

1996-01-01

296

Doppler-like effect and doubtful expansion of universe  

CERN Multimedia

The distance contraction, as observed in electrical soundings over horizontally stratified earth (static system), is identified as a counterpart of Doppler shift in dynamical systems. Identification of Doppler-like effect in a stock-still systems makes it possible to give an al-ternative answer to the question about an effective cause of the Doppler shift, which sounds: the inhomogeneities. This answer opens different static as well as kinematic possibilities, which challenge established theories of expanding universe and energizing big bang.The energy propagating in stratified universe of layers exhibits a shift which could be at-tributed not only to the expansion (Hubble's theory) but alternatively to fluctuations in material properties (inhomogeneities).

Szaraniec, E

2003-01-01

297

Ultrasound Doppler vector tomography measurements of directional blood flow.  

Science.gov (United States)

An experimental system has been developed to verify the possibility of detecting flow activity using a technique called ultrasound Doppler vector tomography. A tomography algorithm is used to reconstruct blood flow vector fields using data from computer-controlled ultrasound continuous-wave Doppler scanning equipment. The result is a picture in which the brightness variations represent the reconstructed values of the curl of the velocity field (inverted delta x v). Continuous ultrasound is transmitted into a region with flow activity and the Doppler-shifted signals are received. To obtain measurement data suited for fan beam tomography, the scanning is performed in a plane from points encircling the region. Reconstructions have been achieved using measurement data from two different flow phantoms. A comparison between the experimental results and simulations shows good conformity. PMID:9080617

Jansson, T; Almqvist, M; Stråhlén, K; Eriksson, R; Sparr, G; Persson, H W; Lindström, K

1997-01-01

298

Ultrasound Doppler vector tomography measurements of directional blood flow.  

UK PubMed Central (United Kingdom)

An experimental system has been developed to verify the possibility of detecting flow activity using a technique called ultrasound Doppler vector tomography. A tomography algorithm is used to reconstruct blood flow vector fields using data from computer-controlled ultrasound continuous-wave Doppler scanning equipment. The result is a picture in which the brightness variations represent the reconstructed values of the curl of the velocity field (inverted delta x v). Continuous ultrasound is transmitted into a region with flow activity and the Doppler-shifted signals are received. To obtain measurement data suited for fan beam tomography, the scanning is performed in a plane from points encircling the region. Reconstructions have been achieved using measurement data from two different flow phantoms. A comparison between the experimental results and simulations shows good conformity.

Jansson T; Almqvist M; Stråhlén K; Eriksson R; Sparr G; Persson HW; Lindström K

1997-01-01

299

A Human Gait Classification Method Based on Radar Doppler Spectrograms  

Directory of Open Access Journals (Sweden)

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

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

2010-01-01

300

Echocardiographic and Doppler echocardiographic findings in 11 wolves (Canis lupus).  

Science.gov (United States)

Two-dimensional real-time, M-mode and Doppler echocardiographic measurements were made in 11 adult wolves (Canis lupus) anaesthetised with an intramuscular combination of medetomidine, ketamine, butorphanol and acepromazine followed by isoflurane in oxygen. M-mode measurements of the left ventricle, B-mode measurements of the left atrium and aorta, systolic indices, and Doppler measurements of aortic and pulmonary blood outflow, and of mitral and tricuspid blood inflow, were recorded. The values obtained were compared with those reported for dogs of similar bodyweight and body type. The diastolic measurements of the cardiac chambers and walls were similar to those reported for healthy, conscious dogs, but the use of anaesthesia probably resulted in the markedly different systolic cardiac measurements, systolic indices and Doppler blood flow velocities observed in the wolves. Mild mitral regurgitation, probably due to mitral endocardiosis, was observed in one wolf, and trivial functional mitral insufficiency was observed in five others. PMID:16443838

Guglielmini, C; Rocconi, F; Brugnola, L; Valerio, F; Mattei, L; Boari, A

2006-01-28

 
 
 
 
301

Echocardiographic and Doppler echocardiographic findings in 11 wolves (Canis lupus).  

UK PubMed Central (United Kingdom)

Two-dimensional real-time, M-mode and Doppler echocardiographic measurements were made in 11 adult wolves (Canis lupus) anaesthetised with an intramuscular combination of medetomidine, ketamine, butorphanol and acepromazine followed by isoflurane in oxygen. M-mode measurements of the left ventricle, B-mode measurements of the left atrium and aorta, systolic indices, and Doppler measurements of aortic and pulmonary blood outflow, and of mitral and tricuspid blood inflow, were recorded. The values obtained were compared with those reported for dogs of similar bodyweight and body type. The diastolic measurements of the cardiac chambers and walls were similar to those reported for healthy, conscious dogs, but the use of anaesthesia probably resulted in the markedly different systolic cardiac measurements, systolic indices and Doppler blood flow velocities observed in the wolves. Mild mitral regurgitation, probably due to mitral endocardiosis, was observed in one wolf, and trivial functional mitral insufficiency was observed in five others.

Guglielmini C; Rocconi F; Brugnola L; Valerio F; Mattei L; Boari A

2006-01-01

302

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)

2009-01-01

303

Delay and Doppler spreads in underwater acoustic particle velocity channels.  

UK PubMed Central (United Kingdom)

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

Guo H; Abdi A; Song A; Badiey M

2011-04-01

304

Detection and Characterization of Extrasolar Planets through Doppler Spectroscopy  

CERN Multimedia

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

Eggenberger, A

2009-01-01

305

Application of pulsed Doppler lidar in the airport terminal area  

Science.gov (United States)

Pulsed coherent Doppler lidar systems have matured rapidly, especially at solid-state wavelengths. Turnkey systems are commercially available and are being deployed for various aviation applications. Doppler lidar data is used in the airport terminal area to map hazardous wind shear and turbulence levels and to detect and track wake vortices. Future applications could include slant path visibility monitoring. Several permanent installations and rapidly deployable instrument configurations have been achieved. The benefit of the infrared Doppler lidar relative to its microwave counterparts is the ability to sense clear air hazards, especially those in and around local terrain features. The fact that the lidar beam is quite narrow eliminates artifacts associated with sidelobe-induced ground clutter. This paper summarizes our autonomous pulsed lidar developments and reviews sample results.

Hannon, Stephen M.; Barr, Keith S.; Jacob, Donald K.; Phillips, Mark W.

2005-01-01

306

Doppler ultrasonography in lower extremity peripheral arterial disease.  

UK PubMed Central (United Kingdom)

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

Verim S; Ta?ç? I

2013-04-01

307

Lorentz invariance and the rotor Doppler shift experiments  

International Nuclear Information System (INIS)

It is shown that 'Rotor Doppler shift Experiments' provide a way to distinguish Einstein's Special Relativity (SR) from Lorentz's Aether Theory (LAT). Misconceptions in previous papers involving the Doppler shift experiments are examined. The theoretical and experimental data available on rotor Doppler shift experiments are analysed. Two models of SR violating theories are used to predict the output of a recently proposed experiment by Torr and Kolen. The first one corresponds to (strict) LAT and the other to an extended form of LAT. Contrary to the first, the second theory leads to results in agreement with the preliminary experimental data of Torr et al indicating a breakdown both of SR and strict LAT. (Author)

1984-01-01

308

Lorentz invariance and the rotor Doppler shift experiments  

International Nuclear Information System (INIS)

It is shown that 'Rotor Doppler shift Experiments' provide a way to distinguish Einstein's Special Relativity (SR) from Lorentz's Aether Theory (LAT). Misconceptions in previous papers involving the Doppler shift experiments are examined. The theoretical and experimental data available on rotor Doppler shift experiments are analysed. Two models of SR violating theories are used to predict the output of a recently proposed experiment by Torr and Kolen. The first one corresponds to (strict) LAT and the other to an extended form of LAT Contrary to the first, the second theory leads to results in agreement with the preliminary experimental data of Torr et al indicating a breakdown both of SR and strict LAT. (Author)

1984-01-01

309

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

2007-01-01

310

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

UK PubMed Central (United Kingdom)

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.

Takahashi I; Furukawa K; Ohishi W; Takahashi T; Matsumoto M; Fujiwara S

2013-01-01

311

Browsing a wealth of millimeter-wavelength doppler spectra data  

Energy Technology Data Exchange (ETDEWEB)

The ARM Climate Research Facility has collected an extensive archive of vertically pointing millimeter wavelength Doppler radar spectra at both 35 and 95 GHz. These data are a rich potential source of detailed microphysical and dynamical cloud and precipitation information. The recording of spectra, which is ongoing, began at the Southern Great Plains site in September of 2003, at the North Slope of Alaska site in April 2004, and at Tropical Western Pacific sites in 2006. Spectra are also being collected during ARM Mobile Facility deployments. The data’s temporal resolution is as high as two seconds, at height intervals of 45 to 90 m. However, the sheer volume of available data can be somewhat daunting to access and search for specific features of interest. Here we present a user interface for spectra browsing, which allows the user to view time-height images of radar moments, select a time or height of interest, and then “drill down” through images of spectrograms to individual Doppler spectra or time- and height-sequences of spectra. Also available are images summarizing spectral characteristics, such as number of spectral peaks, spectral shape information (skewness and kurtosis), moment uncertainty estimates, and hydrometeor vs. clutter identification as produced by the ARM MicroARSCL (Microphysical Active Remote Sensing of Clouds) value-added product. In addition to the access and visualization tools, we are developing a Doppler spectra simulator capable of generating Doppler spectra from liquid, mixed-phase, and solid cloud constituents and precipitation. The Doppler spectra simulator can be used as an interface between explicit microphysics models and Doppler spectra observations from the ARM radars. The plan is to ultimately make the spectra simulator available from within the spectra browser, allowing a user to associate observed spectra with the microphysical conditions capable of producing them.

Johnson,K.; Luke,E.; Kollias, P.; Remillard, J.; Widener, K.; Jensen, M.

2010-03-15

312

New measurement of the relativistic Doppler shift in neon  

Energy Technology Data Exchange (ETDEWEB)

The Doppler free two photon transition from the metastable 1S{sub 5} to 4S{sub 1}{prime}{double_prime} in neon was measured for both a fast beam ({approx}120 keV) and a slow thermal beam. The transition frequencies for each beam were measured independently relative to a hyperfine component of a nearby I{sub 2} reference line. The absolute frequency shift between the two beams was obtained. This measurement of the relativistic Doppler shift verifies the time dilation effect to an accuracy of 2.3 ppm which represents a more than 10 fold improvement over previous measurements.

McGowan, R.W.; Giltner, D.M.; Sternberg, S.J.; Lee, S.A.

1993-05-01

313

Pubertal varicocele: correlation between clinical, Doppler, and hormonal findings.  

Science.gov (United States)

Clinical, Doppler, and hormonal findings in puberal patients with unilateral and bilateral varicocele were evaluated. No correlation was found between clinical and hormonal findings. A significant increase was found in LH response to LH-RH in patients with bilateral varicocele as well as an increase in T to hCG in those with unilateral varicocele with prolonged reflux. Further longitudinal, hormonal, and Doppler studies in puberal patients might provide information about the most useful parameters to define those individuals at higher risk of having future problems. PMID:8458482

Fideleff, H; Boquete, H; Saskyn, N; Zanchetti, F; Ambiela, R; Sobrado, P; Perco, M; Holland, M

1993-03-01

314

ULTRASONOGRAFÍA DOPPLER EN EMBARAZOS DE TÉRMINO CON OLIGOHIDROAMNIOS AISLADO  

Directory of Open Access Journals (Sweden)

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

Marcelo Rodríguez G; Gabriela Egaña U; Rolando Márquez A

2010-01-01

315

Focusing SAR data with time-varying Doppler centroid  

Science.gov (United States)

SAR data spatially sampled at the Nyquist limit can be correctly processed if the Doppler centroid is precisely known. Whenever the Doppler centroid shows rapid variations either with range or azimuth, more care is required in order to take advantage of the computational efficiency of frequency domain techniques. In this paper it is shown that such focusing techniques can still be exploited, provided that SAR raw data are previously modified and a space-varying monodimensional filter is applied to the focused image. The computational cost increases, but it is still smaller than time-space domain processing. Results obtained with simulated SIR-C/X-SAR data and SPOTlight geometries are presented.

Prati, Claudio; Rocca, Fabio

1992-05-01

316

[Doppler technologies in combined diagnosis of acute pyelonephritis].  

Science.gov (United States)

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

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

317

Reference beam laser Doppler velocimeter incorporating fiber optic components  

Energy Technology Data Exchange (ETDEWEB)

A compact reference beam laser Doppler velocimeter, constructed using a semiconductor laser diode, optical fiber components and semiconductor detectors, is reported. The device has been designed to overcome many of the problems commonly associated with reference beam configurations. The anemometer may be operated with the laser diode operating in cw and pulsed modes, demonstrating its applicability to wavelength and time division multiplexing schemes for 3D laser Doppler velocimetry. The probe is used to measure the velocity of a spinning disk in the range {minus}20 m/s to +20 m/s.

James, S.W.; Lockey, R.A.; Egan, D.; Tatam, R.P. [Cranfield Univ., Bedford (United Kingdom)

1995-12-31

318

Aerial ultrasonic micro Doppler sonar detection range in outdoor environments.  

UK PubMed Central (United Kingdom)

Current research demonstrates that micro Doppler sonar has the capability to uniquely identify the presence of a moving human, making it an attractive component in surveillance systems for border security applications. Primary environmental factors that limit sonar performance are two-way spreading losses, ultrasonic absorption, and backscattered energy from the ground that appears at zero Doppler shift in the sonar signal processor. Spectral leakage from the backscatter component has a significant effect on sonar performance for slow moving targets. Sonar performance is shown to rapidly decay as the sensor is moved closer to the ground due to increasing surface backscatter levels.

Bradley M; Sabatier JM

2012-03-01

319

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

1983-01-01

320

Power spectra of fluid velocities measured by laser Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

The power spectrum and the correlation of the laser Doppler velocimeter velocity signal obtained by sampling and holding the velocity at each new Doppler burst are studied. Theory valid for low fluctuation intensity flows shows that the measured spectrum is filtered at the mean sample rate and that it contains a filtered white noise spectrum caused by the steps in the sample and hold signal. In the limit of high data density, the step noise vanishes and the sample and hold signal is statistically unbiased for any turbulence intensity.

Adrian, R.J.; Yao, C.S.

1987-01-01

 
 
 
 
321

Study of Coincidence Doppler Broadening in Carbon Nanotubes  

International Nuclear Information System (INIS)

[en] Coincidence Doppler broadening measurements of positron annihilation for multi-walled carbon nanotubes, double-walled carbon nanotubes, single-walled carbon nanotubes and graphite were performed. The ratio curves of the Doppler broadening for these samples to silicon were obtained. It is shown that there are distinct peaks at the position of 10×10-3m0c for both carbon nanotubes and graphite, however the amplitudes of the peaks are not the same. We have the opinion that these peaks arise from the annihilation of positron with the 2s and 2p electron of carbon element.

2012-01-01

322

Clinical use of laser Doppler flowmetry in a burns unit.  

UK PubMed Central (United Kingdom)

Laser Doppler Flowmetry (LDF) is a new noninvasive technique by which microcirculation changes in tissue can be studied. This has been done in a Burns Unit on burned as well as non-burned patients (volunteers). There were no infection problems with this device in a Burns Unit. Four kHz was the upper wave length limit analysing the doppler signal from burns. A topical temperature load test was defined and used in different situations. Homogeneous flows in reference points from a control group were demonstrated in unheated and heated skin, in this way standardizing the LDF analyses of skin microflow. Ability of LDF to define different degrees of burns was demonstrated.

Micheels J; Alsbjörn B; Sørensen B

1984-01-01

323

System-on-chip based Doppler radar occupancy sensor.  

UK PubMed Central (United Kingdom)

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

Yavari E; Song C; Lubecke V; Boric-Lubecke O

2011-01-01

324

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

325

Color Doppler imaging of cardiac catheters using vibrating motors.  

Science.gov (United States)

A miniature motor rotating at 11,000 rpm was attached onto the proximal end of cardiac electrophysiological (EP) catheters in order to produce vibrations at the tip that were then visualized by color Doppler on ultrasound scanners. The catheter tip was imaged within a vascular graft submerged in a water tank using the Volumetrics Medical Imaging 3D scanner, the Siemens Sonoline Antares 2D scanner and the Philips ie33 3D ultrasound scanner with TEE probe. The vibrating catheter tip was visualized in each case, although results varied with the color Doppler properties of the individual scanner. PMID:19514134

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

2008-10-01

326

Doppler and range determination for deep space vehicles using active optical transponders.  

UK PubMed Central (United Kingdom)

This paper describes and analyzes two types of laser system employing active transponders that could accurately determine Doppler and range to deep space vehicles from earth-orbiting satellites. The first is a noncoherent optical system in which the Doppler effect on an intensity-modulating subcarrier is measured. The second is a coherent optical system in which the Doppler effect of the optical carrier itself is measured. Doppler and range measurement errors are mathematically modeled and, for three example systems, numerically evaluated.

Kinman PW; Gagliardi RM

1988-11-01

327

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

Directory of Open Access Journals (Sweden)

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

Claudio E Scherle-Matamoros; Jesús Pérez-Nellar

2011-01-01

328

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

Scientific Electronic Library Online (English)

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

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

2011-03-01

329

Echocardiographic predictors of adverse clinical events in children with dilated cardiomyopathy: a prospective clinical study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objectives: To compare tissue Doppler (TD) velocities between patients with dilated cardiomyopathy (DCM) and normal controls and to determine whether TD velocities, Tei index, right ventricular fractional area change, and left ventricular ejection fraction (LVEF) predict adverse clinical outcomes in...

McMahon, C J; Nagueh, S F; Eapen, R S; Dreyer, W J; Finkelshtyn, I; Cao, X; Eidem, B W; Bezold, L I; Denfield, S W; Towbin, J A

330

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose spectral domain Doppler optical coherence tomography (SD-D-OCT) to qualitatively measure red blood cell aggregation. Variance/standard deviation (SD) of the Doppler frequency spectrum in Doppler variance imaging of flowing blood under shearing conditions was developed as a new aggregation...

Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

331

Laser Doppler velocimetry: a new technique for the measurement of intestinal mucosal blood flow.  

UK PubMed Central (United Kingdom)

Laser Doppler velocimetry is a technique for continuous measurement of blood flow changes in tissue utilizing the Doppler shift principle. The authors describe a study designed to evaluate laser Doppler velocimetry measurement of blood flow in the canine small intestinal mucosa compared with electromagnetically measured total flow to the isolated segment of the intestine.

Feld AD; Fondacaro JD; Holloway GA Jr; Jacobson ED

1984-08-01

332

Comparison between oscillometric- and Doppler-ABI in elderly individuals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Takahashi, Ikuno; Furukawa, Kyoji; Ohishi, Waka; Takahashi, Tetsuya; Matsumoto, Masayasu; Fujiwara, Saeko

333

Comparison between oscillometric- and Doppler-ABI in elderly individuals  

Science.gov (United States)

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 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.

Takahashi, Ikuno; Furukawa, Kyoji; Ohishi, Waka; Takahashi, Tetsuya; Matsumoto, Masayasu; Fujiwara, Saeko

2013-01-01

334

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

2013-06-27

335

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; Luka? Ilona

2006-01-01

336

Doppler Radar for Heartbeat Rate and Heart Rate Variability Extraction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Obeid, Dany; Sadek, Sawsan; Zaharia, Gheorghe; El Zein, Ghaïs

337

Two new types of laser doppler flowmeters prototypes validation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A fluxometria laser Doppler (LDF) é uma técnica para avaliação em tempo real do fluxo microcirculatório em tecidos biológicos. Esta técnica pode ser usada para monitorização não invasiva da microcirculação (por exemplo, avaliação da perfusão na pele), ou para monitorização da perfusão de forma invas...

Campos, Rita Helena Pinto Oliveira

338

Diagnostic usefulness of findings in Doppler sonography for amelanotic melanoma.  

UK PubMed Central (United Kingdom)

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.

Kato M; Mabuchi T; Yamaoka H; Ikoma N; Tamiya S; Ozawa A; Taguchi M; Kuramochi A; Tsuchida T

2013-09-01

339

Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-05-04

340

Doppler study of uterine hemodynamics in women with unexplained infertility.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To evaluate uterine artery blood flow using pulsed Doppler, and endometrial and subendometrial microvascularization using three-dimensional (3D) power Doppler, in women with unexplained infertility. STUDY DESIGN: In a prospective clinical trial at a university teaching hospital, 40 women with unexplained infertility were compared to 40 fertile parous controls. In the mid-luteal (peri-implantation) phase, the endometrial thickness and volume, uterine artery pulsatility index (PI) and resistance index (RI), endometrial and subendometrial 3D power Doppler vascularization index (VI), flow index (FI), and vascularization flow index (VFI), and serum estradiol and progesterone levels were measured in both groups. RESULTS: The uterine artery PI (P=0.003) and RI (P=0.007) were significantly increased and the endometrial VI (P=0.029), FI (P=0.031), and VFI (P=0.001) and subendometrial VI (P=0.032), FI (P=0.040), and VFI (P=0.005) were significantly decreased in the unexplained infertility group. The endometrial thickness and volume and serum estradiol and progesterone levels, however, were not significantly different between the two groups. CONCLUSION: Peri-implantation endometrial perfusion is impaired in women with unexplained infertility: Doppler study of uterine hemodynamics should therefore be considered in infertility work-up.

El-Mazny A; Abou-Salem N; Elshenoufy H

2013-08-01

 
 
 
 
341

Doppler ultrasonographic evaluation of twins discordant for Rh alloimmunization.  

UK PubMed Central (United Kingdom)

Minimally invasive methods have been used successfully to diagnose and treat maternal red blood cell alloimmunization. We present a case of a dizygotic twin pregnancy discordant for the Rh allele. Serial Doppler ultrasonography helped to diagnose the fetus that was at-risk for anemia caused by Rh alloimmunization and to direct treatment.

Chmait RH; Hull AD

2002-07-01

342

Christian Andreas Doppler--the man and his legacy.  

UK PubMed Central (United Kingdom)

AIMS: Reminding the life and legacy of the Austrian Scientist who discovered the famous 'Doppler Effect'. METHODS AND RESULTS: C.A. Doppler was born the 29th of November 1803 in Salzburg. After studies in Linz and Vienna, he graduated in mathematics, became assistant at the University and later worked as a professor in Prague. Back to Vienna, he was appointed as professor at the Polytechnic School and --in 1850--as first director of the new Institute of Physics. C.A. Doppler did publish on magnetism, electricity, optics, and astronomy. He remains in the history of science due to the discovery presented (May 25, 1842) at the Royal Bohemian Society of Science entitled "On the colored light of the double stars and certain other stars of the heavens"; the paper described (applied to light) the shift of frequency which bears nowadays his name. The theory was later experimentally proven and--extended for any electromagnetic and acoustic waves--got myriads if applications in astronomy, physics, aviation, meteorology, and health science. Satomura in Japan (1955) published it's first ultrasound vascular application--with successive achievements in the next decades. CONCLUSION: Doppler ultrasonagraphy became the main noninvasive instrument for functional assesment of heart and vessels.

Coman IM

2005-01-01

343

Pediatric imaging/doppler ultrasound of the chest: Extracardiac diagnosis  

Energy Technology Data Exchange (ETDEWEB)

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

Huhta, J.C.

1986-01-01

344

Doppler ultrasonographic changes in the canine kidney during normovolaemic anaemia.  

UK PubMed Central (United Kingdom)

The haemodynamics of the canine left renal artery (LRA) and interlobar artery (ILA) were evaluated in eleven fasted, healthy, conscious beagles with severe acute (haematocrit [Hct] 16%), moderate chronic (Hct 26%) and mild chronic (Hct 34%) normovolaemic anaemia using Doppler ultrasound. Heart rate, peak systolic velocity (PSV), end diastolic velocity (EDV), time-averaged mean velocity (TAVmean), pulsatility index (PI) and resistive index (RI) were recorded. Doppler values in the dogs following the induction of anaemia states were compared with corresponding values in the same dogs prior to the induction of anaemia. Left renal artery mean PSV, mean PI and mean RI were significantly higher and the mean EDV was significantly lower in severe acute anaemia. No significant change was seen in mean values of the same parameters in moderate or mild chronic anaemia. There was no significant change in TAVmean of the LRA or mean PI and mean RI of the ILA in any grade of anaemia. Acute, severe normovolaemic anaemia significantly altered LRA Doppler parameters in resting dogs without influencing those of the ILA. Moderate or mild chronic anaemia had no effect on any renal Doppler parameter.

Koma LM; Kirberger RM; Scholtz L

2006-02-01

345

Results of the observations with Doppler receiver DOG-2.  

Science.gov (United States)

In this paper a general description of the operation of the Doppler receiver DOG-2, produced in Poland, is presented as well as the actual results of determination of the Borowiec geocentric coordinates obtained from observations made by the use of that receiver. Processing of data was performed with the program GEODOP.

Fraczyk, P.; Jak?, W.

346

Doppler radar velocity measurements for wound ballistics experiments.  

UK PubMed Central (United Kingdom)

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

Knudsen PJ; Svender J

1994-01-01

347

Solar Supergranulation Waves Detected in Surface Doppler Shift  

CERN Document Server

Recently Gizon, Duvall and Schou (2002) suggested that supergranulation has a wave-like component. In this paper I show that the same phenomenon can be observed using surface Doppler shift data, thereby confirming their observations. I am also able to measure the dispersion relation to lower wavenumbers and to extend the results for rotation and meridional flows beyond +/-70 degrees latitude.

Schou, J

2002-01-01

348

Supergranular waves observed using MDI surface Doppler shift data  

Science.gov (United States)

Recently Gizon, Duvall and Schou (2002) suggested that supergranulation has a wave-like component. Here I show that the phenomenon can also be observed using surface Doppler shift data and extend their results. I also show results for rotation and meridional flows beyond ±70° latitude inferred using the supergranular waves and look for temporal variations in the various properties.

Schou, Jesper

2003-02-01

349

Electric dissociation within left atrial appendage diagnosed by Doppler echocardiography.  

UK PubMed Central (United Kingdom)

We describe a patient who presented with a transient ischemic event in whom transesophageal echocardiography showed presence of an accessory lobe within the left atrial appendage that was in atrial fibrillation by pulsed wave Doppler when the left and right atrial appendages, pulmonary vein, and right atria were in sinus rhythm.

Naqvi TZ; Zaky J

2004-10-01

350

Investigation of Frequency Analysis Methods for Doppler Ultrasound Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Due to the advances of electronic and semiconductor technologies in recent years, it is possible to realize complex, low cost, low size, and low power consumption, high-speed signal processing devices. The progress of these devices has enabled the development of the medical Doppler ultrasound sys...

Tatsuro Baba

351

[Doppler ultrasound to detect Rh: a systematic review].  

UK PubMed Central (United Kingdom)

BACKGROUND: Red cell alloimmunization is an important cause of perinatal morbidlity and mortality. Invasive procedures used to diagnose fetal anemia are associated with serious fetal and maternal complications. The development of noninvasive techniques as Doppler ultrasound can help us in the fetal anemia diagnosis. OBJECTIVES: To evaluate the effect of the Doppler ultrasound in prediction of fetal anemia caused by red cell alloimmunization. Strategy search: Relevant studies were identified by reviewing the registry of COCHRANE, and OVID, PROQUEST, MEDLINE and EMBASE data bases from 1966 to 2004. Selection criteria: All prospective studies with clinically relevant results with comparison of Doppler ultrasound in fetal umbilical artery, fetal descendent aorta, middle cerebral fetal artery or esplecnic fetal artery with hemoglobin or fetal hematocrit. Data collection and analysis: Data were extracted from each report. The quality revision of the studies and the data compilation were made by the reviewers. MAIN RESULTS: Eighteen articles were included. Two studies reached the level of evidence 1 for diagnostic tests. The diagnostic tests had variations depending on the different cut-off of each study. Studies with level 1 of evidence reported detection of 100% for moderate to severe fetal anemia. CONCLUSIONS: Implementation of Doppler ultrasound for prediction of fetal anemia in complicated pregnancies with alloimmunization could reduce the number of invasive procedures and therefore its complications. The level of present evidence reveals to us that the studies do not fulfill the criteria of methodological quality.

Acevedo Gallegos S; Guzmán Huerta ME; Gallardo Gaona JM; Velásquez Torres B; Benavides Serralde JA

2005-05-01

352

Relativistic Doppler effect in a uniformly accelerated motion - III  

CERN Document Server

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

Paiva, F M

2008-01-01

353

A simplified study of trans-mitral Doppler patterns  

Directory of Open Access Journals (Sweden)

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

Thomas George

2008-01-01

354

Dual beam translator for use in Laser Doppler anemometry  

Energy Technology Data Exchange (ETDEWEB)

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

Brudnoy, David M. (Albany, NY)

1987-01-01

355

Dual beam translator for use in Laser Doppler anemometry  

Energy Technology Data Exchange (ETDEWEB)

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

Brudnoy, D.M.

1984-04-12

356

Resolution enhancement of Doppler frequency measurements using a centroid technique  

Energy Technology Data Exchange (ETDEWEB)

A centroid-based technique for locating peaks in the frequency spectrum is demonstrated to have the potential for substantially enhancing the resolution of Fourier-based laser Doppler velocimetry measurements. The effect of data windowing and signal-to-noise ratio on the potential resolution improvement is also analyzed. (orig.)

Naguib, A. [Mechanical Engineering, Michigan State University East Lansing, MI (United States)

2002-05-01

357

Methodology and reproducibility of bidirectional laser Doppler velocimetry  

International Nuclear Information System (INIS)

[en] 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)

1990-01-01

358

Laser doppler velocimetry of the retinal blood flow.  

UK PubMed Central (United Kingdom)

The principles of laser doppler velocimetry, as applied to the measurement of retinal blood flow, are described. The technique offers the possibility of non-invasive clinical measurement; either continuous sequential measurements or repeated intermittent estimates can be made. The field of application is outlined.

Hill DW; Pike ER; Gardner K

1981-01-01

359

Varicocele: laparoscopic clipping and colour Doppler follow-up  

Digital Repository Infrastructure Vision for European Research (DRIVER)

PURPOSE: The aim of this study was to evaluate the results of laparoscopic treatment of varicocele and findings of testicular volume and blood supply using color Doppler ultrasound scan on follow-up. METHODS: Fourteen patients aged 7 to 15 years old (median, 12.3 years) with left varicocele (grade I...

Sun, N; Cheung, TT; Khong, PL; Chan, KL; Tam, PKH

360

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 an...

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

 
 
 
 
361

Cyclotron autoresonance maser with high Doppler frequency up-conversion.  

Science.gov (United States)

A linear induction acceleration (LIA) unit with explosive emission was used as a basis for CARM with high Doppler frequency up-conversion. Using a high-selective Bragg resonator as an electrodynamic system of CARM we investigated two regimes having essent...

O. V. Arkhipov V. L. Bratman G. G. Denisov

1992-01-01

362

Coherent localization exhibited by unequal Auger Doppler components  

International Nuclear Information System (INIS)

[en] If coherent superpositions such as the symmetry eigenstates gerade and ungerade are in turn coherently superimposed, localization occurs. This effect is studied by the intensities of the Doppler components of electrons emitted from dissociating fragments of superexcited O2. The measurements show clear evidence for such coherent localization.

2012-11-05

363

WIND: the joint French-German airborne Doppler lidar  

Science.gov (United States)

An airborne coherent Doppler Lidar to retrieve mesoscale wind fields has been developed in the frame of the Franco- German WIND project. The instrument is based on a pulsed CO2 laser transmitter, heterodyne detection and wedge scanner. The performance of the instrument operating on the ground and in the aircraft is reported.

Flamant, Pierre H.; Werner, Christian; Koepp, Friedrich; Loth, Claude; Delville, P.; Reitebuch, Oliver; Boitel, Ch.; Bruneau, Didier; Drobinski, Ph.; Haering, R.; Herrmann, H.; Klier, Michael; Lopez, M.; Meissonnier, Mireille; Nagel, Engelbert; Romand, B.; Sauvage, L.; Schrecker, M.; Streicher, Juergen; Wildgruber, Guenter

1999-12-01

364

Validar: a testbed for advanced 2-micron Doppler lidar  

Science.gov (United States)

High-energy 2-micron lasers have been incorporated in a breadboard coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Sample data is presented on wind profiling and CO2 concentration measurements.

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

2004-09-01

365

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

366

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

A study examining the utility of transcranial Doppler ultrasound for the determination of cerebral vasospasm following subarachnoid haemorrhage is reported. A control group of 21 patients and a second group of 20 patients suffering from subarachnoid haemorrhage or aneurysm and a group of 26 with oth...

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

367

Preoperative risk assessment for carotid occlusion by transcranial Doppler ultrasound.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVES: An endovascular carotid balloon occlusion test with continuous intracranial monitoring by transcranial Doppler sonography was performed in 55 patients for prediction of tolerance of a required permanent occlusion of the carotid artery. METHODS: Blood flow velocities of the ipsilateral mi...

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

368

Cerebrovascular reactivity in hypertensive patients: A transcranial doppler study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We studied the usefulness of transcranial Doppler sonography for assessing changes in vasoreactivity in patients with hypertension and the hemodynamic consequences of hypertension. METHODS: The study group comprised 25 patients with chronic severe hypertension and 25 age- and sex-matched healthy sub...

Ficzere, Andrea; Valikovics, Attila; Fülesdi, Béla; Juhász, Attila; Czuriga, István; Csiba, László; Csiba László (1952-) (neurológus)

369

Do hematocrit and serum fibrinogen influence transcranial Doppler measurements?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To investigate the effect of hematocrit and serum fibrinogen on transcranial Doppler ultrasound (TCD) measurements, we performed, TCD tests and measured hematocrit and serum fibrinogen concentrations in 112 healthy adult volunteers. The mean velocities of the middle cerebral (r = -.37, p < .0001), i...

Sohn, Y. H.; Kim, G. W.; Kim, J. S.

370

Diagnosis of brain death by transcranial Doppler sonography.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The blood flow velocities in the basal cerebral arteries can be recorded at any age by transcranial Doppler sonography. We examined nine children with either initial or developing clinical signs of brain death. Soon after successful resuscitation increased diastolic flow velocities indicated a proba...

Bode, H; Sauer, M; Pringsheim, W

371

A Preliminary Investigation of Bird Classification by Doppler Radar.  

Science.gov (United States)

A preliminary study of the application of Doppler radar to the classification of birds is reported. The desirability for improvements in bird classification stems primarily from the hazards they present to jet aircraft in flight and in the vicinity of air...

L. W. Martinson

1973-01-01

372

[Myocardial function analysis with echocardiography-Doppler in septic shock].  

UK PubMed Central (United Kingdom)

Septic shock is a severe sepsis associated with cardio-circulatory failure and tissular hypoperfusion. Echocardiography-Doppler remains essential for the assessment of myocardial function in septic shock. This ultrasound procedure helps clinicians for the analysis of left ventricular systolic function, left ventricular diastolic function, right ventricular function and cardiac filling.

Fayssoil A; Checinski A

2012-02-01

373

An automated carotid pulse assessment approach using Doppler ultrasound  

Digital Repository Infrastructure Vision for European Research (DRIVER)

During cardiac arrest emergencies, lay rescuers are required to manually check the patient's carotid pulse after the delivery of defibrillation shocks to assess the cardiac resuscitation progress of the patient. As a more automated way of monitoring the resuscitation progress, a new Doppler-ultrasou...

Yu, ACH; CohenSolal, E; Raju, BI; Ayati, S

374

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

2005-01-01

375

Tissue doppler echocardiography for evaluating left ventricular functions in obese  

Directory of Open Access Journals (Sweden)

Full Text Available Objective: The aim of this study was to investigate theimpact of childhood obesity on ventricular functions usingtissue Doppler echocardiography.Materials and methods: The mitral tissue Doppler signalswere recorded in the apical four-chamber view, with thesample volume placed at the lateral walls of mitral annulus.The mitral flow was examined with the sample Pulse Dopplerpositioned parallely to flow just at the orifice of the mitralleaflets. Twenty obese (mean age, 161.5±25.8 months)and 20 healthy children (mean age, 151.2±33.5 months)were included to this study.Results: Body mass index (BMI) was significantly higherin obese group (30.92±6.87). Isovolumic relaxation time(IVRT) which is one of the left ventricular (LV) diastolicfunction parameters was 66.10±7.30 ms in obese group,and 58.70±9.06 ms in the control group. IVRT was significantlyhigher in the obese group (p=0.007). In obesegroup, the mitral annulus tissue Doppler E velocity wasdecreased, flow velocity was increased and decrement inEm/Am ratio was significant. We found significant negativecorrelation between BMI and LV Em/Am ratio. Myocardialperformance index (MPI) in obese group and control groupwas 0.50±0.07 and 0.41±0.04, respectively (p<0.001).Between MPI and LV Em/Am ratio there was a significantnegative correlation while MPI showed positive correlationwith BMI. In obese group septal and LV posterior wall thicknesswas shown to be significantly increased compared tothe control group (p<0.001).Conclusion: Our findings, may be important for determinationof the relationship between obesity and cardiovascularrisk factors in children. Tissue Doppler echocardiographicimaging may be useful in revealing this relationship.Key words: obesity, doppler echocardiography, ventricular dysfunction

Mecnun Çetin; Mustafa Ça?layan; Münevver Y?ld?r?mer; Baran Serdar K?z?ly?ld?z; Murat Deveci; ?enol Co?kun

2013-01-01

376

[Doppler study of porcine bioprosthesis at the mitral site  

UK PubMed Central (United Kingdom)

Twenty-nine asymptomatic patients with porcine (9 Liotta, 8 Carpentier, 8 Hancock and 4 Xenomedica) mitral prosthesis without clinical findings of prosthetic dysfunction and with normal M-mode and two-dimensional echocardiography were studied with pulsed and continuous wave Doppler. The following parameters of prosthetic function were evaluated: 1) maximum velocity (Vmax); 2) mean pressure gradient; 3) pressure half-time (P 1/2 t); 4) functional prosthetic area or Doppler orifice area (DOA); 5) mitral prosthetic regurgitation (MR); 6) tricuspid regurgitation (TR), if associated. P 1/2 t reproducibility was tested. For the study of the bioprosthetic function the transducer was located in apical position with the best alignment between ultrasonic beam and flow direction in the apical four-chamber view. The best acoustic signal was the guide to an optimal Doppler recording, analyzed for calculations. In 26 patients without MR at Doppler examination Doppler data were as follows: Vmax 1.6 +/- 0.2 m/sec (1.2-2 m/sec); mean pressure gradient: 4.4 +/- 2.7 mmHg (1.4-13 mmHg); P 1/2 t = 94.2 +/- 19.8 msec (55-140 msec); DOA = 2.4 +/- 0.6 cm2 (1.5-4 cm2). Mild unsuspected MR was detected in 3 patients, but the other parameters did not differ from those of the other 26 patients. TR was found in 10 patients. The degree of reproducibility of P 1/2 t was 0.92. Only the P 1/2 t value was longer among Hancock and Liotta or Xenomedica bioprosthesis (p = 0.005). Furthermore P 1/2 t was longer in the patients with longer follow-up periods than in the others (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Montemurro D; Ronzani G; Bobbio M; Orzan F; Brusca A

1987-04-01

377

[Doppler study of porcine bioprosthesis at the mitral site].  

Science.gov (United States)

Twenty-nine asymptomatic patients with porcine (9 Liotta, 8 Carpentier, 8 Hancock and 4 Xenomedica) mitral prosthesis without clinical findings of prosthetic dysfunction and with normal M-mode and two-dimensional echocardiography were studied with pulsed and continuous wave Doppler. The following parameters of prosthetic function were evaluated: 1) maximum velocity (Vmax); 2) mean pressure gradient; 3) pressure half-time (P 1/2 t); 4) functional prosthetic area or Doppler orifice area (DOA); 5) mitral prosthetic regurgitation (MR); 6) tricuspid regurgitation (TR), if associated. P 1/2 t reproducibility was tested. For the study of the bioprosthetic function the transducer was located in apical position with the best alignment between ultrasonic beam and flow direction in the apical four-chamber view. The best acoustic signal was the guide to an optimal Doppler recording, analyzed for calculations. In 26 patients without MR at Doppler examination Doppler data were as follows: Vmax 1.6 +/- 0.2 m/sec (1.2-2 m/sec); mean pressure gradient: 4.4 +/- 2.7 mmHg (1.4-13 mmHg); P 1/2 t = 94.2 +/- 19.8 msec (55-140 msec); DOA = 2.4 +/- 0.6 cm2 (1.5-4 cm2). Mild unsuspected MR was detected in 3 patients, but the other parameters did not differ from those of the other 26 patients. TR was found in 10 patients. The degree of reproducibility of P 1/2 t was 0.92. Only the P 1/2 t value was longer among Hancock and Liotta or Xenomedica bioprosthesis (p = 0.005). Furthermore P 1/2 t was longer in the patients with longer follow-up periods than in the others (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3653588

Montemurro, D; Ronzani, G; Bobbio, M; Orzan, F; Brusca, A

1987-04-01

378

Doppler ultrasound scan during normal gestation: umbilical circulation  

International Nuclear Information System (INIS)

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

2002-01-01

379

Non-Gaussianity and CMB aberration and Doppler  

Science.gov (United States)

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

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

2013-09-01

380

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-03-25

 
 
 
 
381

The evaluation of doxorubicin-induced cardiotoxicity: comparison of Doppler and tissue Doppler-derived myocardial performance index.  

UK PubMed Central (United Kingdom)

BACKGROUND: Doxorubicin is a chemotherapeutic agent used in a wide spectrum of cancers. However, cardiotoxic effects have limited its clinical use. The early detection of doxorubicin-induced cardiotoxicity is crucial. The purpose of our study was to assess values of Doppler and tissue Doppler imaging (TDI)-derived myocardial performance index (MPI) in adult cancer patients receiving doxorubicin treatment. METHODS: A total of 45 patients underwent echocardiographic examinations before any doxorubicin had been administered and then after doxorubicin. Doppler and TDI-derived MPI of left ventricular (LV) were determined in the evaluation of cardiotoxicity. Additionally, TDI-derived MPI of right ventricular (RV) was determined. RESULTS: All patients underwent control echocardiographic examination after mean 5 ± 1.7 months. The LV MPI obtained by both Doppler and TDI were increased after doxorubicin treatment (0.56 ± 0.11, 0.61 ± 0.10, p = 0,005 vs 0.51 ± 0.09, 0.59 ± 0.09, p = 0.001, respectively). There was no correlation between Doppler-derived MPI and cumulative doxorubicin dose (coefficient of correlation 0.11, p = 0.6). TDI-derived MPI was correlated with cumulative doxorubicin dose (coefficient of correlation 0.35, p = 0.015), but this correlation is weak (r = 0.38). The study population was divided into two groups according to doxorubicin dose (below and above 300 mg level). There was a moderate correlation between TDI-derived MPI and less than 300 mg of doxorubicin dose (coefficient of correlation 0.51, p = 0.028). However, Doppler-derived MPI was not correlated with less than 300 mg of doxorubicin dose (coefficient of correlation 0.38, p = 0.123). Also, there was no significant change in the TDI-derived RV-MPI (0.49 ± 0.14, 0.50 ± 0.12, p = 0.56). CONCLUSIONS: TDI-derived MPI is a useful parameter and an early indicator compared with Doppler-derived MPI in the detection of cardiotoxicity during the early stages. Also, doxorubicin administration does not affect RV function.

Ayhan SS; Özdemir K; Kayrak M; Bacaksiz A; Vatankulu MA; Eren Ö; Koc F; Duman C; Gülec H; Demir K; Ari H; Sönmez O; Gök H

2012-01-01

382

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

Scientific Electronic Library Online (English)

Full Text Available 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 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 s (more) iguiente 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, 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 m (more) edicine 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.

Victoria-Gómez, Pablo Andrés

2006-09-01

383

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

2006-01-01

384

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.

2004-01-01

385

Doppler factor, Lorentz factor and viewing angle of superluminal quasars  

Science.gov (United States)

We carried out the investigation of the properties of features seen within superluminal sources often referred to as components. Our result indicates a fairly strong correlation of r˜0.76 between component radial distance L and component size ?. Assumption of simple ballistic motion and free adiabatic expansion, enabled us to use the observed jet component parameters to constrain the Doppler factor, Lorentz factor and the lower limit to the viewing angle with respect to a distant observer. The estimated average Doppler factor, Lorentz factor and viewing angle respectively are 10.3±5.0, 18.3±6.2 and 3.7±2.3 for ?=4/3; while the values obtained for ?=5/3 are 12.2±5.9,17.2±5.1 and 2.9±1.6, where ? is the adiabatic index. The large scatter in our results may be due to the uncertainties introduced by the assumptions made.

Onuchukwu, C. C.; Ubachukwu, A. A.

2013-07-01

386

Technology and Spin-Offs from Doppler Global Velocimetry  

UK PubMed Central (United Kingdom)

The development of Doppler Global Velocimetry as a flow diagnosticmeasurement system necessitated several innovations to solveproblems found during wind tunnel testing. These innovations rangedfrom ratioing a data image with a reference image to remove scatteredlight variations, dewarping the images to remove optical distortions,and to the use of virtual wind tunnels created with 3-D computeranimation technology to test potential optical configurations andpresent the resulting data. The paper describes Doppler GlobalVelocimetry and its development through laboratory and wind tunnelinvestigations, and the various techniques used to solve the problemsuncovered during these tests. Several of these solutions are presentedas potential spin-offs that can enhance and improve a wide variety ofglobal measurement technologies.IntroductionThe development of modern aircraft has become a complicated andexpensive undertaking. Characteristics such as fuel economy,environmental impac...

James F. Meyers

387

Doppler reflectometry for the investigation of poloidally propagating density perturbations  

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-09-15

388

Gravity theories, Transverse Doppler and Gravitational Redshifts in Galaxy Clusters  

CERN Multimedia

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

389

Pulsed doppler analysis of human fetal blood flow  

International Nuclear Information System (INIS)

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

1986-01-01

390

Multipath-dominant, pulsed doppler analysis of rotating blades  

CERN Multimedia

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

Robinson, Michael

2012-01-01

391

SIGACE, Code for Doppler broadening of ACE-formatted files  

International Nuclear Information System (INIS)

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

2006-01-01

392

Normal and anomalous Doppler effects in periodic waveguide cyclotron maser  

Energy Technology Data Exchange (ETDEWEB)

A linear analysis of the periodic-waveguide cyclotron (PWC) maser shows that the PWC interaction with fast-waves possesses properties of the known anomalous Doppler resonance interaction if the wave impedance of the resonant spatial harmonic, Z{sub n}, is much smaller than the free space impedance, i.e. if Z{sub n} {much_lt} Z{sub 0}. The feasibility of a fast-wave PWC interaction in a low impedance waveguide is examined theoretically in this paper. A practical scheme of a slotted-waveguide PWC operating in the fundamental harmonic near cutoff is proposed for a future experiment. The possible advantages of the quasi-anomalous Doppler effect in the fast-wave-PWC operating regime are the alleviation of the initial electron rotation and a high-efficiency operation.

Korol, M.; Jerby, E. [Tel Aviv Univ., Ramat Aviv (Israel)

1995-12-31

393

Evaluation of a bronchial anastomosis by laser Doppler velocimetry.  

UK PubMed Central (United Kingdom)

Healing after bronchoplasty was evaluated by assessing the bronchial mucosal blood flow by laser Doppler velocimetry in dogs. Bronchoplastic surgery at the right main bronchus was performed and bronchial mucosal blood flow was determined by laser Doppler velocimetry at proximal and distal sides of the anastomosis before and after operation. Four experimental groups were established. After operation the blood flow was adequately preserved, and healing of the anastomosis site was satisfactory in the minimum detachment group and steroid-treated group. Mucosal blood flow was markedly reduced in both proximal and distal sides in the extensive detachment group. The extent of the reduction in the blood flow was smaller in the omentum dressing group than in the extensive detachment group. The state of healing of the anastomosis site was closely related to the bronchial mucosal blood flow.

Inui K; Wada H; Yokomise H; Lee M; Yamazaki F; Aoki M; Hitomi S

1990-04-01

394

Clinical use of laser Doppler flowmetry in a burns unit.  

Science.gov (United States)

Laser Doppler Flowmetry (LDF) is a new noninvasive technique by which microcirculation changes in tissue can be studied. This has been done in a Burns Unit on burned as well as non-burned patients (volunteers). There were no infection problems with this device in a Burns Unit. Four kHz was the upper wave length limit analysing the doppler signal from burns. A topical temperature load test was defined and used in different situations. Homogeneous flows in reference points from a control group were demonstrated in unheated and heated skin, in this way standardizing the LDF analyses of skin microflow. Ability of LDF to define different degrees of burns was demonstrated. PMID:6234654

Micheels, J; Alsbjörn, B; Sørensen, B

1984-01-01

395

Left coronary arterial blood flow: Noninvasive detection by Doppler US  

Energy Technology Data Exchange (ETDEWEB)

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

Gramiak, R.; Holen, J.; Moss, A.J.; Gutierrez, O.H.; Picone, A.L.; Roe, S.A.

1986-06-01

396

[The use of doppler echography with contrast in gynecology].  

UK PubMed Central (United Kingdom)

The first studies on the clinical use of ultrasound contrast agents (UCAs) with contrast specific imaging techniques were published at the beginning of this century. A couple of years later sulphur hexafluoride (SonoVue, Bracco, Milan) was marketed in Europe. CEUS has a number of distinct advantages over CT and MRI. It can be performed immediately, without any preliminary laboratory testing. Neoangiogenesis is the typical process related to all malignant tumors, and attempts to investigate the abnormal vascularization of ovarian cancer have been performed using color and power Doppler. The addition of contrast media, could help to discriminate benign and malignant ovarian masses. Doppler enhancement in the ovarian arteries were significantly different, with faster onset, higher intensity, and longer duration in malignant tumors. The use of contrast media has been extensively applied to the diagnosis of adenomyosis, endometrial cancer cervical cancer and preoperative evaluation of the presence and the depth of invasion.

Malinova M

2012-01-01

397

[The use of doppler echography with contrast in gynecology].  

Science.gov (United States)

The first studies on the clinical use of ultrasound contrast agents (UCAs) with contrast specific imaging techniques were published at the beginning of this century. A couple of years later sulphur hexafluoride (SonoVue, Bracco, Milan) was marketed in Europe. CEUS has a number of distinct advantages over CT and MRI. It can be performed immediately, without any preliminary laboratory testing. Neoangiogenesis is the typical process related to all malignant tumors, and attempts to investigate the abnormal vascularization of ovarian cancer have been performed using color and power Doppler. The addition of contrast media, could help to discriminate benign and malignant ovarian masses. Doppler enhancement in the ovarian arteries were significantly different, with faster onset, higher intensity, and longer duration in malignant tumors. The use of contrast media has been extensively applied to the diagnosis of adenomyosis, endometrial cancer cervical cancer and preoperative evaluation of the presence and the depth of invasion. PMID:23236671

Malinova, M

2012-01-01

398

Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler  

Energy Technology Data Exchange (ETDEWEB)

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

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

1990-04-01

399

Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler  

International Nuclear Information System (INIS)

Transcranial Doppler ultrasound is a relatively new diagnostic modality which allows the non-invasive assessment of intracranial circulation. A total of 10 migraine patients were studied and compared to healthy controls without headaches. Migraineurs during the headache-free interval demonstrated excessive cerebrovascular reactivity to CO2, evidenced by an increase in middle cerebral artery blood flow velocity of 47% ± 15% compared to 28% ± 14% in controls. Differences between the two study groups revealed no significant decrease in middle cerebral artery blood flow velocity with hypocapnia. However, the differences between middle cerebral artery blood flow velocity during hyperventilation and CO2 inhalation were significantly different comparing migraineurs and controls. Instability of the baseline blood flow velocities was also noted in migraineurs during the interictal period. Characteristics which may allow differentiation of migraineurs from other headache populations could possibly be obtained from transcranial Doppler ultrasound flow studies. 24 refs., 2 tabs

1990-01-01

400

System-on-chip based Doppler radar occupancy sensor.  

Science.gov (United States)

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

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

2011-01-01

 
 
 
 
401

A compact designed receiver for Molecular Doppler lidar  

Science.gov (United States)

A mobile molecular Doppler lidar at an eye-safe 355nm wavelength based on double-edge technique for wind measurement from 10 km to 40 km altitude is being built in Hefei, China. As the key component of the Doppler lidar, the receiver subsystem is designed elaborately. A triple Fabry-Perot etalon is used as the frequency discriminator whose parameters are optimized. The thermal and mechanics stabilities are considered during the receiver design. The designed receiver system is very compact and stable, which could be embedded into a standard 19 inch socket bench with 21 inch length. With this new kind of receiver, the optical alignment is easy and the stability of the etalon transmittance, which is of great importance to the wind measurement, is expected to be improved.

Shen, Fahua; Sun, Dongsong

2011-10-01

402

MRI and colour-Doppler in sclerosing mesenteritis  

International Nuclear Information System (INIS)

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

1992-01-01

403

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; Juriši? Vladimir; Kerkez Mirko

2008-01-01

404

Analytical theory of Doppler reflectometry in slab plasma model  

Energy Technology Data Exchange (ETDEWEB)

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)

Gusakov, E.Z.; Surkov, A.V. [Ioffe Institute, Politekhnicheskaya 26, St. Petersburg (Russian Federation)

2004-07-01

405

A Combinatorical Approach to Vector Tomography for Doppler Spectral Data  

UK PubMed Central (United Kingdom)

Velocity spectra of a flow can be made by ultrasound Doppler measurements. Using only part of the information in these spectra, it is possible to reconstruct the solenoid part and the support of the flow. Here we demonstrate that using a local minimisation combinatorical algorithm and a certain neighbourhood structure it is possible to reconstruct all of the flow, hence also the divergence. In simulations the reconstructions are very close to the original full flow.

K. Strhln

406

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

407

Simultaneous Doppler maps of IP Peg in outburst  

CERN Multimedia

IP Pegasi is an eclipsing dwarf nova lying above the period gap with an orbital period of 3.8h. It is the first cataclysmic variable to show evidence of spiral arms in its accretion disc. We present new time-resolved echelle spectroscopic observations of IP Peg, covering the 3900-7700 Angstrom range. This allows us to produce simultaneous Doppler Maps in 9 emission lines.

Papadaki, C; Steeghs, D

2004-01-01

408

[Doppler ultrasound imaging of the carotid and vertebral arteries].  

UK PubMed Central (United Kingdom)

The prevalence of carotid artery diseases increases with age and exposure to cardiovascular risk factors. Significant carotid artery stenosis is closely associated with the development of stroke and cerebrovascular events. Doppler ultrasound imaging is a noninvasive and useful modality for the examination of carotid and vertebral arteries. However, proper investigation of the carotid artery system requires sufficient technical knowledge and experience. This review gives information about the techniques of appropriate examination of the carotid artery system.

Yurdakul S; Aytekin S

2011-09-01

409

Three-dimensional Doppler anemometer using a holographic optical element.  

UK PubMed Central (United Kingdom)

A new simple 3-D laser Doppler system has been developed for simultaneous measurement of the instantaneous velocity vector of a scattering particle. The system is based on the reference beam method. It uses a hologram to generate the reference beams. Only one laser operating in single mode is required as the light source. The system has been tested by measuring all the components of the Reynolds stress tensor in a round cold air jet. The results are presented.

Schneider F; Windein W

1988-11-01

410

Pulsed Doppler duplex sonography and CT of portal vein thrombosis  

Energy Technology Data Exchange (ETDEWEB)

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

Miller, V.E.; Berland, L.L.

1985-07-01

411

Pulsed Doppler duplex sonography and CT of portal vein thrombosis  

International Nuclear Information System (INIS)

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

1985-01-01

412

Evaluation of coherent Doppler lidar velocity estimators in nonstationary regimes.  

UK PubMed Central (United Kingdom)

We evaluate the mean velocity estimator performance for coherent Doppler lidar measurements of wind fields with wind shear and nonuniform system response as a function of target range. Performance of the velocity estimates is characterized by the bias and standard deviation that are determined by computer simulations. Results are for solid-state lasers with a Gaussian transmitted pulse. We consider data with high signal energy that produces negligible random outliers.

Lottman BT; Frehlich RG

1997-10-01

413

Autonomous Beam Alignment for Coherent Doppler Lidar With Multielement Detectors  

Science.gov (United States)

Autonomous beam alignment for coherent Doppler lidar requires accurate information about optical misalignment and optical aberrations. A multielement heterodyne detector provides the required information without a loss in overall system performance. The effects of statistical variations from the random backscattered field (speckle field) are determined with computer simulations for both ground-based operation with a fixed calibration target and for space-based operation with random target backscatter.

Frehlich, Rod

1999-11-01

414

Autonomous beam alignment for coherent Doppler lidar with multielement detectors.  

UK PubMed Central (United Kingdom)

Autonomous beam alignment for coherent Doppler lidar requires accurate information about optical misalignment and optical aberrations. A multielement heterodyne detector provides the required information without a loss in overall system performance. The effects of statistical variations from the random backscattered field (speckle field) are determined with computer simulations for both ground-based operation with a fixed calibration target and for space-based operation with random target backscatter.

Frehlich R

1999-11-01

415

Evaluation of coherent Doppler lidar velocity estimators in nonstationary regimes.  

Science.gov (United States)

We evaluate the mean velocity estimator performance for coherent Doppler lidar measurements of wind fields with wind shear and nonuniform system response as a function of target range. Performance of the velocity estimates is characterized by the bias and standard deviation that are determined by computer simulations. Results are for solid-state lasers with a Gaussian transmitted pulse. We consider data with high signal energy that produces negligible random outliers. PMID:18264319

Lottman, B T; Frehlich, R G

1997-10-20

416

Adaptive cancellation of harmonic interferences in transcranial Doppler signal  

Science.gov (United States)

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

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

2004-07-01

417

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.

2007-01-01

418

[Venous Doppler velocimetry: ten years of development of a method].  

Science.gov (United States)

Doppler velocimetry enables three haemodynamic parameters that are extremely useful for the study of venous diseases to be evaluated: blood flow direction, the morphology of the velocity wave and venous pressure. These three parameters are used in association depending on the particular requirements of the diagnostic problem. In the case of suspected deep venous thrombosis, study of the morphology of the velocity wave and clinostatism pressure give good diagnostic possibilities for the iliaco-femoral axis but poor for the leg trunks. In post-thrombotic syndrome, Doppler velocimetry is not so useful because the patient has to remain immobile during the examination while this specific pathology features insufficiency of the muscular pump during walking. In varicose disease, the investigation offers a very high diagnostic capability by evidencing the site and extent of valvular incontinence in the saphena and perforating vessels. The only limitation is the presence of numerous incontinent perforating vessels, but this is infrequent. In this pathology, Doppler v. has almost completely supplanted phlebography because it responds to the needs of modern medicine to replace invasive diagnostic investigations with non-invasive techniques that are equally effective. Finally, two other fields of application are very important for this investigation: the study of a patient with varices prior to saphenic stripping and prior to sclerotherapy. Definition of the origin and course of the reflux ways makes an optimal result possible, even allowing for the evolution of varicosity. PMID:2192304

Annoni, F; Lovaria, A; Pezzoni, F; Saccheri, S; Ceva, M

1990-02-01

419

[Venous Doppler velocimetry: ten years of development of a method  

UK PubMed Central (United Kingdom)

Doppler velocimetry enables three haemodynamic parameters that are extremely useful for the study of venous diseases to be evaluated: blood flow direction, the morphology of the velocity wave and venous pressure. These three parameters are used in association depending on the particular requirements of the diagnostic problem. In the case of suspected deep venous thrombosis, study of the morphology of the velocity wave and clinostatism pressure give good diagnostic possibilities for the iliaco-femoral axis but poor for the leg trunks. In post-thrombotic syndrome, Doppler velocimetry is not so useful because the patient has to remain immobile during the examination while this specific pathology features insufficiency of the muscular pump during walking. In varicose disease, the investigation offers a very high diagnostic capability by evidencing the site and extent of valvular incontinence in the saphena and perforating vessels. The only limitation is the presence of numerous incontinent perforating vessels, but this is infrequent. In this pathology, Doppler v. has almost completely supplanted phlebography because it responds to the needs of modern medicine to replace invasive diagnostic investigations with non-invasive techniques that are equally effective. Finally, two other fields of application are very important for this investigation: the study of a patient with varices prior to saphenic stripping and prior to sclerotherapy. Definition of the origin and course of the reflux ways makes an optimal result possible, even allowing for the evolution of varicosity.

Annoni F; Lovaria A; Pezzoni F; Saccheri S; Ceva M

1990-02-01

420

Advances in Doppler recognition for ground moving target indication  

Science.gov (United States)

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

Kealey, Paul G.; Jahangir, Mohammed

2006-06-01

 
 
 
 
421

The Doppler paradigm and the APEX-EPOS-ORANGE quandary  

Energy Technology Data Exchange (ETDEWEB)

The experimental detection of the sharp lines of the (e{sup +}e{sup -}) 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 (< 3 keV wide) electron line in few MeV e{sup +} or e{sup -} bombardments of U and Th targets could prove crucial.

Griffin, J.J.

1995-12-31

422

Considerations pertinent to the Doppler effect for space reactors  

Energy Technology Data Exchange (ETDEWEB)

Because of the potential importance of the Doppler effect to the safety considerations of compact fast spectrum reactors for space applications, extensive investigations have been carried out. The purpose of this paper is two-fold. First, the magnitude of the Doppler reactivity of such reactors will be estimated. Secondly, some relevant questions concerning the fundamental nature of the problems will be addressed. In the present study, a generic space reactor design having features of current designs is examined. In R-Z geometry, the reactor consists of 3 core regions which are made of UN with various enrichments mixed in with a W/Re matrix and coolant channels filled with /sup 7/Li and surrounded by Mo-vessel and beryllium oxide reflector along with external control drums made of B/sub 4/C in the radial direction and accompanied by axial regions. The axial region above the core contains BeO with W/Re structure. The enrichment increases as a function of radius to provide an approximately constant power distribution in the core regions. Hence, the temperature distribution is also expected to be approximately constant in various core regions. The Doppler reactivities will be given for various radial and axial regions.

Hwang, R.N.

1987-01-01

423

In vivo feasibility of endovascular Doppler optical coherence tomography.  

UK PubMed Central (United Kingdom)

Feasibility of detecting intravascular flow using a catheter based endovascular optical coherence tomography (OCT) system is demonstrated in a porcine carotid model in vivo. The effects of A-line density, radial distance, signal-to-noise ratio, non-uniform rotational distortion (NURD), phase stability of the swept wavelength laser and interferometer system on Doppler shift detection limit were investigated in stationary and flow phantoms. Techniques for NURD induced phase shift artifact removal were developed by tracking the catheter sheath. Detection of high flow velocity (~51 cm/s) present in the porcine carotid artery was obtained by phase unwrapping techniques and compared to numerical simulation, taking into consideration flow profile distortion by the eccentrically positioned imaging catheter. Using diluted blood in saline mixture as clearing agent, simultaneous Doppler OCT imaging of intravascular flow and structural OCT imaging of the carotid artery wall was feasible. To our knowledge, this is the first in vivo demonstration of Doppler imaging and absolute measurement of intravascular flow using a rotating fiber catheter in carotid artery.

Sun C; Nolte F; Cheng KH; Vuong B; Lee KK; Standish BA; Courtney B; Marotta TR; Mariampillai A; Yang VX

2012-10-01

424

Color Doppler ultrasound imaging of the eye and orbit.  

UK PubMed Central (United Kingdom)

Color Doppler imaging is a non-invasive ultrasound procedure which permits simultaneous gray scale imaging of structure and color-coded imaging of blood velocity. This improved technique allows the user to identify even very small blood vessels, such as those supplying the eye, from which measures of blood velocity and vascular resistance can be obtained. In the past five years, color Doppler imaging has found a number of applications in ophthalmology. A common examination procedure and expected normal values have been established, and the technique is becoming routinely employed to evaluate orbital vasculature in some medical centers. Color Doppler imaging has successfully demonstrated changes in orbital hemodynamics associated with a variety of pathological conditions, including central retinal artery and vein occlusions, cranial arteritis, nonarteritic ischemic optic neuropathy, and carotid disease. In addition, the method has been used to detect the vascularization of orbital and ocular tumors, as well as to investigate altered hemodynamics associated with diseases such as glaucoma and diabetic retinopathy.

Williamson TH; Harris A

1996-01-01

425

Doppler Spectra and Estimated Windspeed of a Violent Tornado.  

Science.gov (United States)

Presented in this Paper are Doppler spectra of a very large tornado that occurred on 22 May 1981 near Binger, Oklahoma. Tracking of the tornado was accomplished with the help of a novel `polar spectra display.' Bimodal tornado spectral signatures (TSS) were observed in about 40 scans. Direct measurements of maximum velocities from spectral skirts yielded a maximum tangential speed of 80 m s1 (90 m s1 relative to ground). A diameter of 1 km at 200 m above ground was deduced from a simplified model. Radial centrifuging of radar targets was estimated to be about 20 m s1. With simple assumptions for radar target sizes and summation of forces, a beamwidth average convergence value of about 2.5 × 102 s1 was calculated for the tornado boundary layer.Tornado damage to trees and structures was subjectively rated on the Fujita damage scale. The windspeed range associated with the damage scale agreed well with the Doppler-estimated maximum windspeed when the tornado was large (1 km diameter). However, as the tornado diameter decreased, the Doppler-derived windspeed considerably underestimated that associated with the damage scale.

Zrni, Dusan; Burgess, Donald W.; Hennington, Larry

1985-10-01