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Sample records for doppler tei index

  1. Value of tissue Doppler-derived Tei index and two-dimensional speckle tracking imaging derived longitudinal strain on predicting outcome of patients with light-chain cardiac amyloidosis.

    PubMed

    Liu, Dan; Hu, Kai; Herrmann, Sebastian; Cikes, Maja; Ertl, Georg; Weidemann, Frank; Störk, Stefan; Nordbeck, Peter

    2017-06-01

    Prognosis of patients with light-chain cardiac amyloidosis (AL-CA) is poor. Speckle tracking imaging (STI) derived longitudinal deformation parameters and Doppler-derived left ventricular (LV) Tei index are valuable predictors of outcome in patients with AL-CA. We estimated the prognostic utility of Tei index and deformation parameters in 58 comprehensively phenotyped patients with AL-CA after a median follow-up of 365 days (quartiles 121, 365 days). The primary end point was all-cause mortality. 19 (33%) patients died during follow-up. Tei index (0.89 ± 0.29 vs. 0.61 ± 0.16, p < 0.001) and E to global early diastolic strain rate ratio (E/GLSRdias) were higher while global longitudinal systolic strain (GLSsys) was lower in non-survivors than in survivors (all p < 0.05). Tei index, NYHA functional class, GLSsys and E/GLSRdias were independent predictors of all-cause mortality risk, and Tei index ≥0.9 (HR 7.01, 95% CI 2.43-20.21, p < 0.001) was the best predictor of poor outcome. Combining Tei index and GLSsys yielded the best results on predicting death within 1 year (100% with Tei index ≥0.9 and GLSsys ≤13%) or survival (95% with Tei index ≤0.9 and GLSsys ≥13%). We conclude that 1-year mortality risk in AL-CA patients can be reliably predicted using Tei index or deformation parameters, with combined analysis offering best performance.

  2. Relationship Between Tei Index and PEP-Derived Myocardial Performance Index in Sinus Rhythm

    PubMed Central

    Besli, Feyzullah; Basar, Cengiz; Ekinozu, Ismail; Turker, Yasin

    2015-01-01

    Abstract The goal of this study was to evaluate the preejection time (PEP)-derived myocardial performance index (MPI) in hypertensive (HT) patients with sinus rhythm and its relationship to the classic Tei index. One hundred five patients were enrolled in the study (65 HT and 40 control subjects). The mean age of all patients was 50.5 ± 15 years and 60% were female. Echocardiography was performed on all patients. MPI was measured with the classic Tei method (MPI-Tei index) and the PEP-derived MPI method by using tissue Doppler echocardiography. Although the MPI-Tei index is defined as the ratio of isovolumetric contraction time (IVCT) along with isovolumetric relaxation time (IVRT) to ejection time (ET), PEP-derived MPI is defined as the ratio of PEP and IVRT to ET. We compared echocardiographic data between the HT group and the control group. MPI-Tei index and the PEP-derived MPI values were higher in the HT group compared with controls (0.52 ± 0.10 vs 0.39 ± 0.07, P < 0.001, and 0.51 ± 0.09 vs 0.39 ± 0.07). PEP-derived MPI was strongly correlated with the MPI-Tei index (r = 0.945, P < 0.001). Our study determined that the PEP-derived MPI might be used in the evaluation of left ventricular function in patients with HT, similar to the classic MPI-Tei index. PMID:26200613

  3. Clinical value of Tei index in pediatric patients with repaired tetralogy of Fallot.

    PubMed

    Song, Bing; Qi, Quan; Liu, Ruisheng; Xing, Wang; Tang, Hanbo; Li, Yuanmin

    2015-01-01

    Tetralogy of Fallot is a congenital heart disease characterized by underdevelopment of the right ventricular infundibulum. Present study aimed to explore the clinic value of Tei index in assessing right ventricular function of pediatric patients with repaired Tetralogy of Fallot. A total of 45 pediatric patients with repaired Tetralogy of Fallot were recruited and classified into: group A (Tei index <0.5; n=13, aging 2-12 years), group B (0.5< Tei index <0.7; n=19, aging 1-14 years), and group C (Tei index >0.7; n=13, aging 4-14 years). The right ventricular Tei index value was related to the clinical characteristics of Tetralogy of Fallot repair patients. Right ventricular Tei index was positively correlated with ventilation time, drainage volumes, and negatively with drug assistance and Intensive Care Unit (ICU) stay, although time for drug assistance and ICU stay were not statically different between group B and group C. There was no significant difference in left ventricular ejection fraction. Tei index is a sensitive indicator of right ventricular dysfunction, and has important clinical value to better our understanding of right ventricular function after tetralogy of Fallot repair.

  4. Clinical value of Tei index in pediatric patients with repaired tetralogy of Fallot

    PubMed Central

    Song, Bing; Qi, Quan; Liu, Ruisheng; Xing, Wang; Tang, Hanbo; Li, Yuanmin

    2015-01-01

    Purpose: Tetralogy of Fallot is a congenital heart disease characterized by underdevelopment of the right ventricular infundibulum. Present study aimed to explore the clinic value of Tei index in assessing right ventricular function of pediatric patients with repaired Tetralogy of Fallot. Methods: A total of 45 pediatric patients with repaired Tetralogy of Fallot were recruited and classified into: group A (Tei index <0.5; n=13, aging 2-12 years), group B (0.5< Tei index <0.7; n=19, aging 1-14 years), and group C (Tei index >0.7; n=13, aging 4-14 years). The right ventricular Tei index value was related to the clinical characteristics of Tetralogy of Fallot repair patients. Results: Right ventricular Tei index was positively correlated with ventilation time, drainage volumes, and negatively with drug assistance and Intensive Care Unit (ICU) stay, although time for drug assistance and ICU stay were not statically different between group B and group C. There was no significant difference in left ventricular ejection fraction. Conclusion: Tei index is a sensitive indicator of right ventricular dysfunction, and has important clinical value to better our understanding of right ventricular function after tetralogy of Fallot repair. PMID:26221356

  5. Evaluation of right ventricular Tei index (index of myocardial performance) in healthy dogs and dogs with tricuspid regurgitation.

    PubMed

    Teshima, Kenji; Asano, Kazushi; Iwanaga, Koji; Koie, Hiroshi; Uechi, Masami; Kato, Yuka; Kutara, Kenji; Edamura, Kazuya; Hasegawa, Atsuhiko; Tanaka, Shigeo

    2006-12-01

    Right ventricular (RV) Tei index (index of myocardial performance) has been demonstrated to be clinically useful in estimating RV function in various human cardiac diseases. The purposes of this study were to validate the correlation between RV Tei index and RV function obtained by cardiac catheterization in healthy dogs, and to evaluate the RV Tei index in dogs with tricuspid regurgitation (TR). In healthy dogs, the RV Tei index significantly correlated with the RV peak +dP/dt (r=-0.80, p<0.0001) and -dP/dt (r=0.69, p=0.0001). In normal dogs, the RV Tei index was not significantly correlated with heart rate, body weight, and age. The RV Tei index significantly increased in dogs with moderate to severe TR (0.39 +/- 0.35, p=0.0015), filariasis (0.46 +/- 0.16, p=0.0131), and trivial to mild TR and severe mitral regurgitation (MR; 0.61 +/- 0.14, p=0.0017) when compared with the normal dogs (0.17 +/- 0.10). In addition, the RV Tei index in dogs with TR significantly increased in association with pulmonary hypertension [PH(-), 0.19 +/- 0.09; PH(+), 0.65 +/- 0.14; respectively p<0.0001]. Our study has demonstrated that RV Tei index is a feasible approach to estimate RV function in dogs and is not influenced by heart rate, body weight, and aging. Further investigations are required to clarify the clinical significance of RV Tei index in dogs with right-sided cardiac diseases.

  6. [Geographical distribution of left ventricular Tei index based on principal component analysis].

    PubMed

    Xu, Jinhui; Ge, Miao; He, Jinwei; Xue, Ranyin; Yang, Shaofang; Jiang, Jilin

    2014-11-01

    To provide a scientific standard of left ventricular Tei index for healthy people from various region of China, and to lay a reliable foundation for the evaluation of left ventricular diastolic and systolic function. The correlation and principal component analysis were used to explore the left ventricular Tei index, which based on the data of 3 562 samples from 50 regions of China by means of literature retrieval. Th e nine geographical factors were longitude(X₁), latitude(X₂), altitude(X₃), annual sunshine hours (X₄), the annual average temperature (X₅), annual average relative humidity (X₆), annual precipitation (X₇), annual temperature range (X₈) and annual average wind speed (X₉). ArcGIS soft ware was applied to calculate the spatial distribution regularities of left ventricular Tei index. There is a significant correlation between the healthy people's left ventricular Tei index and geographical factors, and the correlation coefficients were -0.107 (r₁), -0.301 (r₂), -0.029 (r₃), -0.277 (r₄), -0.256(r₅), -0.289(r₆), -0.320(r₇), -0.310 (r₈) and -0.117 (r₉), respectively. A linear equation between the Tei index and the geographical factor was obtained by regression analysis based on the three extracting principal components. The geographical distribution tendency chart for healthy people's left Tei index was fitted out by the ArcGIS spatial interpolation analysis. The geographical distribution for left ventricular Tei index in China follows certain pattern. The reference value in North is higher than that in South, while the value in East is higher than that in West.

  7. The Effects of Ivabradine on Left Ventricular Synchronization and Tei Index in Patients with Systolic Heart Failure

    PubMed Central

    Erdem, Fatma Hizal; Ozturk, Serkan; Öztürk, Selçuk; Erdem, Alim; Ayhan, Selim; Öztürk, Mustafa; Dönmez, İbrahim; Baltacı, Davut; Yazıcı, Mehmet

    2017-01-01

    Background The aim of our study was to evaluate in stable outpatients with systolic heart failure (HF) the 3 months effect of ivabradine on LV synchronization and Tei index in stable outpatients with systolic HF. Methods We evaluated prospectively 40 (30 males, 10 females) patients with HF. All patients were evaluated before and after treatment by transthoracic M mode, two dimensional (2D), pulsed-wave (PW), continuous wave (CW), color flow and tissue Doppler imaging (TDI) and tissue synchronization imaging (TSI). Standard deviation of Ts of the 12 LV segments (Ts-SD-12) is the most widely used parameter of intra-LV asynchrony. Results Thirty men and 10 women with mean ± SD age of 64.7 ± 9.9 years were included in this study. Most of the patients benefitted from some degree of clinical improvement, 12/16 (75.0%) from NYHA III to II and 18/24 (75.0%) from II to I, respectively. Resting heart rate was significantly reduced after ivabradine treatment (84.3 ± 11.4 vs. 66.5 ± 11.5 bpm, p < 0.001). E/E’ and Tei index were significantly changed after ivabradine treatment (17.3 ± 9.0 vs. 14.8 ± 7.1, p = 0.02 and 0.86 ± 0.74 vs. 0.81 ± 0.69, p = 0.02). Intra-LV synchrony parameters Ts-SD-12 and Ts-12 were significantly reduced after ivabradine (46.8 ± 13.6 vs. 42.7 ± 13.1, p = 0.01 and 142.5 ± 44.0 vs. 128.5 ± 45.2, p = 0.009). Conclusions The present study demonstrated that adding ivabradine to the standard therapy reduced HR and significantly improved LV ventricular asynchrony and Tei index in systolic HF patients. PMID:28115808

  8. Right Ventricular Tissue Doppler in Space Flight

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  10. Splenic Doppler resistive index for early detection of occult hemorrhagic shock after polytrauma in adult patients.

    PubMed

    Corradi, Francesco; Brusasco, Claudia; Garlaschi, Alessandro; Santori, Gregorio; Vezzani, Antonella; Moscatelli, Paolo; Pelosi, Paolo

    2012-11-01

    The objective of this study was to evaluate whether direct assessment of splenic circulation by splenic Doppler resistive index (Doppler RI) is a clinically useful noninvasive method for an early detection of occult hemorrhagic shock after polytrauma in adult patients. Splenic Doppler RI was measured in 49 hemodynamically stable adult patients admitted to the emergency department because of polytrauma. Renal Doppler RI was also determined in 20 patients. Spleen size, Injury Severity Score, systolic blood pressure, heart rate, blood lactate, standard base excess, pH, hemoglobin, and inferior vena cava diameter values were recorded at admission and at 24 h. Patients were grouped according to whether signs of hemorrhagic shock did (n = 22) or did not (n = 27) occur within the first 24 h from admission. Patients who developed hemorrhagic shock had significantly higher splenic and renal Doppler RI, higher Injury Severity Score, and lower standard base excess at admission. By multivariate logistic regression, splenic Doppler RI resulted to be a predictor of hemorrhagic shock development within the first 24 h from admission. Splenic Doppler RI may represent a clinically useful noninvasive method for early detection of occult hemorrhagic shock and persistent occult hypoperfusion after polytrauma in adult patients.

  11. Double Doppler effect in two-dimensional photonic crystal with negative effective index

    NASA Astrophysics Data System (ADS)

    Jiang, Qiang; Chen, Jiabi; Liang, Binming; Zhuang, Songlin

    2016-11-01

    The inverse Doppler effect in photonic crystal with negative refractive index had been proofed experimentally in our previous research. In this paper, we studied the spatial harmonics of Bloch wave propagating in such PhCs by FFT method. The lagging and front phase evolutions reveal that both backward wave and forward wave exist in these harmonics. Subsequently, we studied the double Doppler effect phenomenon that both the normal and inverse Doppler exist in one photonic crystal simultaneously by using the improved dynamic FDTD method which we made it suitable for dealing with moving objects. The simulative Doppler frequency shifts were consistent with the theoretical values. Our study provides a potential technology in measurement area.

  12. Reversing the direction of space and inverse Doppler effect in positive refraction index media

    NASA Astrophysics Data System (ADS)

    Sun, Fei; He, Sailing

    2017-01-01

    A negative refractive index medium, in which all spatial coordinates are reversed (i.e. a left-hand triplet is formed) by a spatial folding transformation, can create many novel electromagnetic phenomena, e.g. backward wave propagation, and inversed Doppler effect (IDE). In this study, we use coordinate rotation transformation to reverse only two spatial coordinates (e.g. x‧ and y‧), while keeping z‧ unchanged. In this case, some novel phenomena, e.g. radiation-direction-reversing illusions and IDE, can be achieved in a free space region wrapped by the proposed shell without any negative refractive index medium, which is easier for experimental realization and future applications.

  13. Doppler sonography in experimentally induced acute renal failure in rabbits. Resistive index versus serum creatinine levels.

    PubMed

    Yoon, D Y; Kim, S H; Kim, H D; Na, D G; Goo, J M; Choi, H J; Yeon, K M; Han, M C

    1995-03-01

    The purpose of this study is to investigate the temporal relation between the change in the resistive index (RI) from renal Doppler sonography and that of serum creatinine values in the course of experimentally induced reversible acute renal failure (ARF) in rabbits. Reversible ARF was induced in 10 New Zealand white rabbits by injecting a glycerol solution (6.0 mL/kg) into the thigh muscle. Doppler sonography was performed before injection, and 6, 12, and 24 hours, and 3, 5, 7, and 14 days after injection of glycerol. Blood samples for measuring serum creatinine levels were obtained in the same time sequence. Three rabbits, which died during the course of the experiment, were excluded from the study group. The RI elevated rapidly after glycerol injection, peaked at 12 hours, and then decreased to normal values by 7 days. Conversely, serum creatinine values were elevated and peaked at 1 day and then decreased to normal by 14 days. The change in the RI preceded the change in serum creatinine levels in the course of reversible ARF. There was a weak linear correlation between RI and serum creatinine levels, with a correlation coefficient of 0.33. Doppler sonography with measurement of resistive index may be useful in predicting the course of ARF.

  14. Experimental verification of the inverse Doppler effect in negative-index material

    NASA Astrophysics Data System (ADS)

    Feng, Lie; Chen, Jiabi; Wang, Yan; Geng, Tao; Zhuang, Songlin

    2010-10-01

    μResearch of negative-index material (NIM) is a very hot developing research field in recent years. NIM is also called left-handed material (LHM), in which the electric field [see manuscript], the magnetic field [see manuscript] and the wave vector [see manuscript] are not composed of a set of right-handed coordinates but a set of left-handed coordinates. Thus the action of electromagnetic waves in both left-handed material and right-handed material is just the opposite, for instance, the negative refraction phenomenon, the inverse Doppler effect and so on. Here we report the explicit result of the inverse Doppler effect through a photonic crystal (PC) prism at 10.6m wavelength for the first time, and the result we get from the experiment is much similar to the theoretical analysis we have deduced before. During the experiment, the CO2 laser is used as a light source, and the PC prism is used as a sample, which can move a tiny distance (1mm) uniformly with a translating stage. Based on the method of optical heterodyne, we let the emergent light from the output surface of PC prism and the reference light from light source interfere at the surface of the detector. When the translating stage moves towards the detector, the optical paths in the PC prism will be changed, and then the Doppler frequency shift will be generated. Though several different samples have been tested repeatedly, the results we get are extraordinarily similar. So we can be sure that the inverse Doppler effect really exists in the NIM at optical frequencies. To our best knowledge, this is the only experimental verification of the inverse Doppler effect in the NIM at optical frequencies at home and aboard.

  15. Amniotic fluid index measured with the aid of color flow Doppler.

    PubMed

    Zlatnik, M G; Olson, G; Bukowski, R; Saade, G R

    2003-04-01

    To determine whether using color flow Doppler to identify the umbilical cord affects amniotic fluid index (AFI) measurements. A total of 2236 AFI measurements between 24 and 42 weeks in singleton gestations with no known or suspected fetal anomalies and < 14 days' discrepancy between menstrual and ultrasonographic dating were included. Color flow Doppler was used to identify loops of umbilical cord; these were excluded from the measurement. Polynomial regression was used to generate means and centiles. Data were grouped according to completed weeks of gestation and descriptive statistics were calculated. At each week of gestation, the number and percentage of pregnancies diagnosed as < or = 2.5th, < or = 5th, > or = 95th, and > or = 97.5th centile according to a 'standard' nomogram derived without using color flow Doppler were calculated. The AFI decreased significantly over gestational age, starting at 31 weeks (p < 0.05 by ANOVA). The relationship between AFI and gestational age was best modeled by a second-degree polynomial (p < 0.001). The median and range of the proportion of AFIs that fell outside the ranges of the standard nomogram at each completed gestational age was: 6.0 (2.3-35.4)% for the < or = 2.5th centile, 9.9 (3.1-37.5)% for the < or = 5th centile, 3.8 (0-30)% for the > or = 95th centile, and 1.8 (0-20)% for the > or = 97.5th centile. The 2.5th and 5th centiles using the current data were lower than those of the 'standard', and the difference increased with advancing gestation. Upper centiles were also different. The AFI measured using color flow Doppler overestimates oligohydramnios and may underestimate polyhydramnios when a standard AFI table obtained without color flow Doppler is used. Normal values specific for measurement method should be used for reference.

  16. Right Ventricular Tissue Doppler in Space Flight

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    Tissue Doppler (TD) registers movement of a given sample of cardiac tissue throughout the cardiac cycle. TD spectra of the right ventricle (RV) were obtained from a long-duration ISS crewmember as a portion of an ongoing experiment ("Braslet" test objective). To our knowledge, this is the first report of RV TD conducted in space flight, and the data represent reproducibility and fidelity of this application in space and serve as the first "space normal" data set. Methods RV TD was performed by astronaut scientists remotely guided by an ultrasound expert from Mission Control Center, Houston, TX. In four of the subjects, RV TD was acquired from the free wall near the tricuspid annulus in two separate sessions 4 to 7 days apart. A fifth subject had only one session. All digital DICOM frames were exported for off-line analysis. Systolic (S ), early diastolic (E ) and late diastolic (A ) velocities were measured. RV Tei-index was calculated using diastolic and systolic time intervals as a combined measure of myocardial performance. Results and Discussion The mean values from the first 4 subjects (8 sessions) were used as the on-orbit reference data, and subject 5 was considered as a hypothetical patient for comparison (see Table). The greatest difference was in the early diastolic A (31 %) yet the standard deviation (a) for A amongst the reference subjects was 2.25 (mean = 16.02). Of interest is the Tei index, a simple and feasible indicator of overall ventricular function; it was similar amongst all the subjects. The late diastolic A seems to compensate for the variance in E . Normal Tei index for the RV is < 0.3, yet our data show all but one subject consistently above this level, notwithstanding their nominal responses to daily exercise in microgravity. These data remind us that the physiology of RV preload in altered gravity environments is still not completely understood.

  17. Testicular resistive index determined by Doppler ultrasonography in men with spinal cord injury - a case series.

    PubMed

    Krebs, J; Göcking, K; Pannek, J

    2015-09-01

    In this case series, the testicular resistive index was determined in men with spinal cord injury. In ten men participating in our fertility programme, the peak systolic and end-diastolic velocity of centripetal testicular arteries was measured in triplicates by Doppler ultrasonography to calculate the testicular resistive index. Furthermore, the right and left testicular volume was determined by ultrasonography, blood samples were obtained for hormonal evaluation, and sperm analysis was performed according to the WHO guidelines. The median testicular resistive index measured 0.69 and was significantly (P < 0.001) greater than the reported cut-off value of 0.6. The spermiograms were characterised by normal sperm count but decreased sperm motility and plasma membrane integrity. The median right and left testicular volume was significantly (P < 0.01) smaller compared to the volumes measured in able-bodied adult males without scrotal pathology and measured 8.4 ml and 7.2 ml respectively. There was a significant (P = 0.005) correlation (rs  = 0.81) between testicular resistive index and sperm concentration. However, no correlations were observed between testicular resistive index and other variables. The testicular resistive index in men with spinal cord injury was significantly greater than 0.6. Measuring the testicular resistive index may represent a useful additional parameter in the assessment of infertility in spinal cord-injured men.

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

    PubMed Central

    Patrlj, Leonardo; Bušić, Željko; Kolovrat, Marijan; Rakić, Mislav; Kliček, Robert; Židak, Marcel; Stipančić, Igor

    2014-01-01

    Many clinical and preclinical studies demonstrated that measurements of liver hemodynamic [Doppler perfusion index (DPI)] may be used to accurately diagnose and predict liver metastases from primary colorectal cancer in a research setting. However, Doppler measurements have some serious limitations when applied to general population. Ultrasound is very operator-dependent, and requires skilled examiners. Also, many conditions may limit the use of Doppler ultrasound and ultrasound in general, such as the presence of air in digestive tract, cardiac arrhythmias, vascular anomalies, obesity and other conditions. Therefore, in spite of the results from clinical studies, its value may be limited in everyday practice. On the contrary, scientific research of the DPI in detection of liver metastases is of great importance, since current research speaks strongly for the presence of systemic vasoactive substance responsible for observed hemodynamic changes. Identification of such a systemic vasoactive substance may lead to the development of a simple and reproducible laboratory test that may reliably identify the presence of occult liver metastases and therefore increase the success of adjuvant chemotherapy through better selection of patients. Further research in this subject is therefore of great importance. PMID:25392837

  19. Ultrasound resistive index, power Doppler, and clinical parameters in established rheumatoid arthritis.

    PubMed

    Bisi, Melissa Cláudia; do Prado, Aline Defaveri; Piovesan, Deise Marcela; Bredemeier, Markus; da Silveira, Inês Guimarães; de Mendonça, José Alexandre; Staub, Henrique Luiz

    2017-04-01

    Ultrasonography (US) is a useful tool for the evaluation of sinovial vascularization and proliferation in rheumatoid arthritis (RA). Accordingly, resistive index (RI) on spectral Doppler (sD) US provides a quantitative analysis of vascular inflammation, but its utility in the evaluation of RA activity has not been established. Our objective was to determine the association of RI with other US parameters of synovitis and with clinical disease activity in established RA. Patients with positive power Doppler (pD) were included in a prospective cross-sectional study. Disease activity and disability were evaluated using the Disease Activity Score in 28-joints (DAS28) and Health Assessment Questionnaire (HAQ), respectively. Gray scale (GS) synovitis, pD, and sD analyses were performed by one of two examiners in wrists and the second and third metacarpophalangeal and proximal interphalangeal joints. The 10-joint GS and 10-joint pD scores and mean RI were then calculated. Weighted kappa (WK) values were employed to assess interobserver reability, and correlations were tested using the Spearman coefficient. Ninety-five RA patients (median duration of disease of 7 years and mean DAS28 of 4.32 ± 1.66) were included. WK values in real-time US were 0.77 for synovitis, 0.87 for pD, and 0.68 for RI. There were no significant correlations of RI with 10-joint GS, 10-joint pD, DAS28, joint counts, or HAQ (P > 0.10 for all tests). Patients in remission had a mean RI similar to those with high disease activity (0.62 ± 0.10, n = 15 versus 0.63 ± 0.13, n = 34, respectively). The addition of the RI score did not seem to improve US performance in patients with established RA.

  20. Fetal umbilical artery Doppler pulsatility index and childhood neurocognitive outcome at 12 years

    PubMed Central

    Mone, Fionnuala; McConnell, Barbara; Thompson, Andrew; Segurado, Ricardo; Hepper, Peter; Stewart, Moira C; Dornan, James C; Ong, Stephen; McAuliffe, Fionnuala M; Shields, Michael D

    2016-01-01

    Objective To determine whether an elevated fetal umbilical artery Doppler (UAD) pulsatility index (PI) at 28 weeks’ gestation, in the absence of fetal growth restriction (FGR) and prematurity, is associated with adverse neurocognitive outcome in children aged 12 years. Methods Prospective cohort study, comparing children with a normal fetal UAD PI (<90th centile) (n=110) and those with an elevated PI (≥90th centile) (n=40). UAD was performed at 28, 32 and 34 weeks gestation. At 12 years of age, all children were assessed under standardised conditions at Queen's University, Belfast, UK to determine cognitive and behavioural outcomes using the British Ability Score-II and Achenbach Child Behavioural Checklist Parent Rated Version under standardised conditions. Regression analysis was performed, controlling for confounders such as gender, socioeconomic status and age at assessment. Results The mean age of follow-up was 12.4 years (±0.5 SD) with 44% of children male (n=63). When UAD was assessed at 28 weeks, the elevated fetal UAD group had lower scores in cognitive assessments of information processing and memory. Parameters included (1) recall of objects immediate verbal (p=0.002), (2) delayed verbal (p=0.008) and (3) recall of objects immediate spatial (p=0.0016). There were no significant differences between the Doppler groups at 32 or 34 weeks' gestation. Conclusions An elevated UAD PI at 28 weeks' gestation in the absence of FGR or prematurity is associated with lower scores of declarative memory in children aged 12 years. A potential explanation for this is an element of placental insufficiency in the presence of the appropriately grown fetus, which affects the development of the fetal hippocampus and information processing and memory long-term. These findings, however, had no impact on overall academic ability, mental processing and reasoning or overall behavioural function. PMID:27311899

  1. The assessment of cardiac functions by tissue Doppler-derived myocardial performance index in patients with Behcet's disease.

    PubMed

    Tavil, Yusuf; Ozturk, Mehmet Akif; Sen, Nihat; Kaya, Mehmet Gungor; Hizal, Fatma; Poyraz, Fatih; Turfan, Murat; Onder, Meltem; Gurer, Mehmet Ali; Cengel, Atiye

    2008-03-01

    Vascular involvement is one of the major characteristics of Behcet's disease (BD). However, there are controversial findings regarding cardiac involvement in BD. Although early reports demonstrated that there is diastolic dysfunction in BD, conflicting results were found in the following trials. Hence, a new method for more objectively estimating the cardiac functions is needed. For this aim, we used high-usefulness tissue Doppler echocardiography for detailed analysis of cardiac changes in BD patients because this method was superior to other conventional echocardiographic techniques. The study population included 42 patients with BD (19 men, 23 women; mean age, 35 +/- 10 years, mean disease duration, 2.7 +/- 1.6 years) and 30 healthy subjects (14 men, 16 women; mean age, 38 +/- 7 years). Cardiac functions were determined using echocardiography, comprising standard two-dimensional and conventional Doppler and tissue Doppler imaging (TDI). Peak systolic myocardial velocity at mitral annulus, early diastolic mitral annular velocity (Em), late diastolic mitral annular velocity (Am), Em/Am, and myocardial performance index (MPI) were calculated by TDI. The conventional echocardiographic parameters and tissue Doppler measurements were similar between the groups. Tissue Doppler derived mitral relaxation time was longer (75 +/- 13 vs 63 +/- 16 msn, p = 0.021) in patients with BD. There was statistically significant difference between the two groups regarding left ventricular MPI (0.458 +/- 0.072 vs 0.416 +/- 0.068%, p = 0.016), which were calculated from tissue Doppler systolic time intervals. There was also significant correlation between the disease duration and MPI (r = 0.38, p = 0.017). We have demonstrated that tissue Doppler-derived myocardial left ventricular relaxation time and MPI were impaired in BD patients, although systolic and diastolic function parameters were comparable in the patients and controls.

  2. Doppler ultrasound measurement of resistance index in the diagnosis of prostate cancer.

    PubMed

    Huang, Wei; Cen, Son; Kang, Xin-Li; Wang, Wei Fu; Wang, Yang; Chen, Xiang

    2015-01-01

    Prostate cancer (PCa) remains the second leading cause of cancer diagnosis worldwide. Early diagnosis and treatment of PCa is critical since the long-term prognosis is excellent in patients with tumors confined to the prostate gland. The current meta-analysis investigates the diagnostic value of resistive index (RI) measurement using color Doppler ultrasound in patients with PCa. Electronic literature databases were exhaustively searched for relevant studies published prior to May 31, 2014. Nine studies met our predetermined inclusion criteria for the present meta-analysis. The methodologic quality of the selected studies was independently assessed by 2 reviewers based on Quality Assessment of Diagnostic Accuracy Studies tool. Our meta-analysis results showed that RI values were significantly higher in malignant prostate tissues compared to normal prostate tissues (standardized mean difference [SMD] 0.42, 95% confidence interval [CI] 0.12~0.73, p = 0.007) and benign prostate tissues (SMD 0.41, 95% CI 0.26~0.56, p<0.001). Subgroup analysis based on the diagnostic instruments used revealed that RI values were accurate in diagnosis of PCa when compared between malignant tissue vs normal tissue and malignant tissue vs benign tissue (all p<0.05). Taken together, our findings support the potential clinical applications of RI values in diagnosis of PCa.

  3. Comparison of index velocity measurements made with a horizontal acoustic Doppler current profiler

    USGS Publications Warehouse

    Jackson, P. Ryan; Johnson, Kevin K.; Duncker, James J.

    2012-01-01

    The State of Illinois' annual withdrawal from Lake Michigan is limited by a U.S. Supreme Court decree, and the U.S. Geological Survey (USGS) is responsible for monitoring flows in the Chicago Sanitary and Ship Canal (CSSC) near Lemont, Illinois as a part of the Lake Michigan Diversion Accounting overseen by the U.S. Army Corps of Engineers, Chicago District. Every 5 years, a technical review committee consisting of practicing engineers and academics is convened to review the U.S. Geological Survey's streamgage practices in the CSSC near Lemont, Illinois. The sixth technical review committee raised a number of questions concerning the flows and streamgage practices in the CSSC near Lemont and this report provides answers to many of those questions. In addition, it is the purpose of this report to examine the index velocity meters in use at Lemont and determine whether the acoustic velocity meter (AVM), which is now the primary index velocity meter, can be replaced by the horizontal acoustic Doppler current profiler (H-ADCP), which is currently the backup meter. Application of the AVM and H-ADCP to index velocity measurements in the CSSC near Lemont, Illinois, has produced good ratings to date. The site is well suited to index velocity measurements in spite of the large range of velocities and highly unsteady flows at the site. Flow variability arises from a range of sources: operation of the waterway through control structures, lockage-generated disturbances, commercial and recreational traffic, industrial withdrawals and discharges, natural inflows, seiches, and storm events. The influences of these factors on the index velocity measurements at Lemont is examined in detail in this report. Results of detailed data comparisons and flow analyses show that use of bank-mounted instrumentation such as the AVM and H-ADCP appears to be the best option for index velocity measurement in the CSSC near Lemont. Comparison of the rating curves for the AVM and H-ADCP demonstrates

  4. Renal Doppler Resistive Index as a Marker of Oxygen Supply and Demand Mismatch in Postoperative Cardiac Surgery Patients

    PubMed Central

    Corradi, Francesco; Brusasco, Claudia; Paparo, Francesco; Manca, Tullio; Santori, Gregorio; Benassi, Filippo; Molardi, Alberto; Gallingani, Alan; Ramelli, Andrea; Gherli, Tiziano; Vezzani, Antonella

    2015-01-01

    Background and Objective. Renal Doppler resistive index (RDRI) is a noninvasive index considered to reflect renal vascular perfusion. The aim of this study was to identify the independent hemodynamic determinants of RDRI in mechanically ventilated patients after cardiac surgery. Methods. RDRI was determined in 61 patients by color and pulse Doppler ultrasonography of the interlobar renal arteries. Intermittent thermodilution cardiac output measurements were obtained and blood samples taken from the tip of pulmonary artery catheter to measure hemodynamics and mixed venous oxygen saturation (SvO2). Results. By univariate analysis, RDRI was significantly correlated with SvO2, oxygen extraction ratio, left ventricular stroke work index, and cardiac index, but not heart rate, central venous pressure, mean artery pressure, pulmonary capillary wedge pressure, systemic vascular resistance index, oxygen delivery index, oxygen consumption index, arterial lactate concentration, and age. However, by multivariate analysis RDRI was significantly correlated with SvO2 only. Conclusions. The present data suggests that, in mechanically ventilated patients after cardiac surgery, RDRI increases proportionally to the decrease in SvO2, thus reflecting an early vascular response to tissue hypoxia. PMID:26605339

  5. Renal Doppler Resistive Index as a Marker of Oxygen Supply and Demand Mismatch in Postoperative Cardiac Surgery Patients.

    PubMed

    Corradi, Francesco; Brusasco, Claudia; Paparo, Francesco; Manca, Tullio; Santori, Gregorio; Benassi, Filippo; Molardi, Alberto; Gallingani, Alan; Ramelli, Andrea; Gherli, Tiziano; Vezzani, Antonella

    2015-01-01

    Renal Doppler resistive index (RDRI) is a noninvasive index considered to reflect renal vascular perfusion. The aim of this study was to identify the independent hemodynamic determinants of RDRI in mechanically ventilated patients after cardiac surgery. RDRI was determined in 61 patients by color and pulse Doppler ultrasonography of the interlobar renal arteries. Intermittent thermodilution cardiac output measurements were obtained and blood samples taken from the tip of pulmonary artery catheter to measure hemodynamics and mixed venous oxygen saturation (SvO2). By univariate analysis, RDRI was significantly correlated with SvO2, oxygen extraction ratio, left ventricular stroke work index, and cardiac index, but not heart rate, central venous pressure, mean artery pressure, pulmonary capillary wedge pressure, systemic vascular resistance index, oxygen delivery index, oxygen consumption index, arterial lactate concentration, and age. However, by multivariate analysis RDRI was significantly correlated with SvO2 only. The present data suggests that, in mechanically ventilated patients after cardiac surgery, RDRI increases proportionally to the decrease in SvO2, thus reflecting an early vascular response to tissue hypoxia.

  6. Doppler-derived myocardial systolic strain rate is a strong index of left ventricular contractility

    NASA Technical Reports Server (NTRS)

    Greenberg, Neil L.; Firstenberg, Michael S.; Castro, Peter L.; Main, Michael; Travaglini, Agnese; Odabashian, Jill A.; Drinko, Jeanne K.; Rodriguez, L. Leonardo; Thomas, James D.; Garcia, Mario J.

    2002-01-01

    BACKGROUND: Myocardial fiber strain is directly related to left ventricular (LV) contractility. Strain rate can be estimated as the spatial derivative of velocities (dV/ds) obtained by tissue Doppler echocardiography (TDE). The purposes of the study were (1) to determine whether TDE-derived strain rate may be used as a noninvasive, quantitative index of contractility and (2) to compare the relative accuracy of systolic strain rate against TDE velocities alone. METHODS AND RESULTS: TDE color M-mode images of the interventricular septum were recorded from the apical 4-chamber view in 7 closed-chest anesthetized mongrel dogs during 5 different inotropic stages. Simultaneous LV volume and pressure were obtained with a combined conductance-high-fidelity pressure catheter. Peak elastance (Emax) was determined as the slope of end-systolic pressure-volume relationships during caval occlusion and was used as the gold standard of LV contractility. Peak systolic TDE myocardial velocities (Sm) and peak (epsilon'(p)) and mean (epsilon'(m)) strain rates obtained at the basal septum were compared against Emax by linear regression. Emax as well as TDE systolic indices increased during inotropic stimulation with dobutamine and decreased with the infusion of esmolol. A stronger association was found between Emax and epsilon'(p) (r=0.94, P<0.01, y=0.29x+0.46) and epsilon'(m) (r=0.88, P<0.01) than for Sm (r=0.75, P<0.01). CONCLUSIONS: TDE-derived epsilon'(p) and epsilon'(m) are strong noninvasive indices of LV contractility. These indices appear to be more reliable than S(m), perhaps by eliminating translational artifact.

  7. Doppler ultrasound velocities and resistive indexes immediately after pediatric liver transplantation: normal ranges and predictors of failure.

    PubMed

    Jamieson, Lucy H; Arys, Bo; Low, Gavin; Bhargava, Ravi; Kumbla, Surekha; Jaremko, Jacob L

    2014-07-01

    We sought to determine the ranges of Doppler ultrasound findings immediately after pediatric liver transplantation that are associated with successful outcomes or postoperative complications. This study included consecutive children who underwent Doppler ultrasound less than 48 hours after liver transplantation from 2001 to 2011. Operative reports and clinical outcome data were recorded. We had 110 patients (54% girls) with mean age at transplantation of 2.9 years (median, 1.3 years; range, 0-14 years) and a median follow-up interval of 3.5 years. Two pediatric radiologists reviewed ultrasound images in consensus. We computed descriptive statistics, interindex correlations, and analysis of variance. Twenty-four of 110 patients had a vascular complication, most commonly hepatic arterial thrombosis (seven patients). Compared with published adult normal values, normal pediatric Doppler parameters at postoperative day 1 trended toward higher normal velocities and resistive indexes (up to 0.95). Absent or low-velocity common hepatic artery flow less than 50 cm/s or a common hepatic artery resistive index less than 0.50 were significantly associated with hepatic artery thrombosis, whereas absent or low-velocity portal venous flow less than 30 cm/s or low-velocity hepatic venous flow less than 25 cm/s were significantly associated with vascular complications and a monotonic hepatic venous waveform was significantly associated with venous complications. Flow in a pediatric liver on the first day after transplantation is normally hyperdynamic, especially in the youngest transplant recipients, and, as a result, low velocities or resistive indexes are particularly concerning for complications. The pediatric-specific ranges of expected posttransplantation Doppler ultrasound findings presented in this article should assist in identifying normal variation and potentially life-threatening complications.

  8. Myocardial Performance Index in Neurocardiogenic Syncope Patients

    PubMed Central

    Yilmaz Coskun, Fatma; Sucu, Murat; Uku, Okkes; Yuce, Murat; Ozer, Orhan; Ercan, Suleyman; Davutoglu, Vedat

    2014-01-01

    Background Many syncopes resulting from neural reflexes in various conditions are called neurocardiogenic syncope (NCS). We aimed to investigate the presence of left ventricular (LV) myocardial performance index (MPI) in patients with NCS, which was diagnosed with head-up tilt table test (HUTT), and the accurateness of the test in order to use it as a method in patients with NCS. Assuming the MPI as a potential cause of syncope, we assessed the Tei index with non-invasive tissue Doppler echocardiography method. Methods Consecutive outpatients with a history of recurrent unexplained syncope underwent HUTT. Twenty-nine HUTT (+) patients (24 female and five male, mean age: 30 ± 15 years) as the study group and HUTT (-) 23 healthy patients (six female and 17 male, mean age: 34 ± 16 years) as the control group were included into the study. Conventional and tissue Doppler echocardiography was performed to both groups. The MPI was determined by using PW Doppler. Measurements of Doppler time intervals, according to Tei index ((isovolumic contraction time + isovolumic relaxation time)/ejection time) is calculated as (a - b/b), where “a” is the interval between cessation and onset of the mitral inflow, and “b” is the ejection time (ET) at the LV outflow. Results When comparing the groups in terms of MPI and ET, there was significant difference between groups. Patients with NCS had significantly longer ET and lower MPI value than control group (284 ± 24 ms vs. 260 ± 24 ms, P < 0.001, respectively and 0.44 ± 0.7 vs. 0.52 ± 0.8, P < 0.001, respectively). There was no significant difference in ejection fraction between groups. Conclusion In the present study, LV MPI value decreases in patients with NCS.

  9. Reliability of Doppler and stethoscope methods of determining systolic blood pressures: considerations for calculating an ankle-brachial index.

    PubMed

    Chesbro, Steven B; Asongwed, Elmira T; Brown, Jamesha; John, Emmanuel B

    2011-01-01

    The purposes of this study were to: (1) identify the interrater and intrarater reliability of systolic blood pressures using a stethoscope and Doppler to determine an ankle-brachial index (ABI), and (2) to determine the correlation between the 2 methods. Peripheral arterial disease (PAD) affects approximately 8 to 12 million people in the United States, and nearly half of those with this disease are asymptomatic. Early detection and prompt treatment of PAD will improve health outcomes. It is important that clinicians perform tests that determine the presence of PAD. Two individual raters trained in ABI procedure measured the systolic blood pressures of 20 individuals' upper and lower extremities. Standard ABI measurement protocols were observed. Raters individually recorded the systolic blood pressures of each extremity using a stethoscope and a Doppler, for a total of 640 independent measures. Interrater reliability of Doppler measurements to determine SBP at the ankle was very strong (intraclass correlation coefficient [ICC], 0.93-0.99) compared to moderate to strong reliability using a stethoscope (ICC, 0.64-0.87). Agreement between the 2 devices to determine SBP was moderate to very weak (ICC, 0.13-0.61). Comparisons of the use of Doppler and stethoscope to determine ABI showed weak to very weak intrarater correlation (ICC, 0.17-0.35). Linear regression analysis of the 2 methods to determine ABI showed positive but weak to very weak correlations (r2 = .013, P = .184). A Doppler ultrasound is recommended over a stethoscope for accuracy in systolic pressure readings for ABI measurements.

  10. Cardiac Functions Assessment in Children with Celiac Disease and its Correlation with the Degree of Mucosal Injury: Doppler Tissue Imaging Study

    PubMed Central

    Fathy, Abeer; Abo-Haded, Hany M.; Al-Ahmadi, Najat; El-Sonbaty, Marwa M.

    2016-01-01

    Background/Aims: Celiac disease (CD)-associated cardiologic disorders is a growing concern. However, data regarding cardiac affection in children with CD are few. This study aimed at assessing the subclinical impact of CD on the global myocardial performance in Saudi children with CD using Doppler tissue imaging (DTI). Patients and Methods: Conventional two-dimensional echocardiography was performed among 20 Saudi children with CDas well as 20 age and sex-matched healthy controls. DTI were used to determine right ventricular (RV) and left ventricular (LV) Tei indexes. These findings were correlated with the Modified Marsh Classification of the histologic findings in CD. Results: LV and RV Tei indexes were significantly higher in children with CD than the control group (mean ± standard deviation: 0.47 ± 0.05 vs. 0.31 ± 0.18; P < 0.0005 and 0.51 ± 0.04 vs. 0.32 ± 0.05; P < 0.0001, respectively). RV Tei index was found to be positively correlated with the Modified Marsh Classification of CD (r = 0.7753, P < 0.0001). LV Tei index tended to be more affected in patients with more severe histologic findings, however, such relation did not reach statistical significance (r = 0.2479, P = 0.292). Fractional shortening did not correlate with the Modified Marsh Classification of histologic findings in CD patients (r= −0.11, P = 0.641). Conclusions: Subclinical myocardial dysfunction of both ventricles occurs in children with CD. The DTI method appears to be more sensitive than conventional two-dimensional echocardiography in the early detection of myocardial dysfunction in children with CD. PMID:27976640

  11. Ambulatory blood pressure and Doppler echocardiographic indexes of borderline hypertensive men presenting an exaggerated blood pressure response during dynamic exercise.

    PubMed

    Herkenhoff, F L; Vasquez, E C; Mill, J G; Lima, E G

    2001-10-01

    Borderline hypertension (BH) has been associated with an exaggerated blood pressure (BP) response during laboratory stressors. However, the incidence of target organ damage in this condition and its relation to BP hyperreactivity is an unsettled issue. Thus, we assessed the Doppler echocardiographic profile of a group of BH men (N = 36) according to office BP measurements with exaggerated BP in the cycloergometric test. A group of normotensive men (NT, N = 36) with a normal BP response during the cycloergometric test was used as control. To assess vascular function and reactivity, all subjects were submitted to the cold pressor test. Before Doppler echocardiography, the BP profile of all subjects was evaluated by 24-h ambulatory BP monitoring. All subjects from the NT group presented normal monitored levels of BP. In contrast, 19 subjects from the original BH group presented normal monitored BP levels and 17 presented elevated monitored BP levels. In the NT group all Doppler echocardiographic indexes were normal. All subjects from the original BH group presented normal left ventricular mass and geometrical pattern. However, in the subjects with elevated monitored BP levels, fractional shortening was greater, isovolumetric relaxation time longer, and early to late flow velocity ratio was reduced in relation to subjects from the original BH group with normal monitored BP levels (P<0.05). These subjects also presented an exaggerated BP response during the cold pressor test. These results support the notion of an integrated pattern of cardiac and vascular adaptation during the development of hypertension.

  12. Doppler index and plasma level of atrial natriuretic hormone are improved by optimizing atrioventricular delay in atrioventricular block patients with implanted DDD pacemakers.

    PubMed

    Toda, N; Ishikawa, T; Nozawa, N; Kobayashi, I; Ochiai, H; Miyamoto, K; Sumita, S; Kimura, K; Umemura, S

    2001-11-01

    Doppler index is the sum of isovolumetric contraction time and isovolumetric relaxation time divided by ejection time and has clinical value as an index of combined systolic and diastolic myocardial performance. This crossover study compared the Doppler index and atrial natriuretic hormone (atrial natriuretic peptide) [ANP] between optimal (AV) delay and prolonged AV delay in patients with DDD pacemakers. The study included 14 patients (6 men, 8 women, age 78.4+/-9.3 [SD] years) with AV block with an implanted DDD pacemaker. AV delay was prolonged in a 25-ms, stepwise fashion starting from 125 ms to 250 ms. Pacing rate was set at 70 beats/min. Cardiac output (CO) was assessed by pulsed Doppler echocardiography, and optimal AV delay was defined as the AV delay at which CO was maximum, and an AV delay setting of 250 ms as prolonged AV delay. Plasma level of ANP and Doppler index determined by echocardiography were measured 1 week after programming. AV delay was switched to another AV delay and measurements were repeated after 1 week. Optimal AV delay was 159+/-19 ms. Doppler index was significantly lower at optimal AV delay than at prolonged AV delay (0.68+/-0.26 vs 0.92+/-0.30, P < 0.05). The plasma ANP level was significantly lower at optimal AV delay than at prolonged AV delay (29.0+/-30.7 vs 52.6+/-44.9 pg/mL, P < 0.05). In conclusion, the Doppler index and the plasma ANP level were significantly lower at optimal AV delay than at prolonged AV delay. This study shows the importance of the optimal AV delay setting in patients with an implanted DDD pacemaker, the Doppler index and plasma ANP levels are good indicators for optimizing AV delay.

  13. [Effect of metabolic uncontrolled diabetes mellitus (DM) on the resistance index of renal (IR) Interlobar arteries assessed with pulsed Doppler].

    PubMed

    Muraira-Cárdenas, Luis Cesar; Barrios-Pérez, Martín

    2016-01-01

    Diabetes mellitus is a chronic degenerative disease characterized by elevated hyperglycemia, triggering a series of processes and culminating in chronic, uncontrolled, cellular and vascular damage in different organs. To assess whether the elevated glycosylated hemoglobin, microalbuminuria, and the time evolution of more than 10 years of diabetes mellitus are associated with elevated resistance index of the interlobar renal arteries assessed with pulsed Doppler in patients with metabolic uncontrolled diabetes mellitus. Transversal-analytical, observational, prospective study that included diabetic patients attending UMAE abdominal ultrasound in 25 of IMSS, from October 15, 2014 to November 15, 2014, which was performed for pulsed Doppler index resistance of vascular interlobar renal arteries and was collected from electronic medical records: age, sex, glycated hemoglobin, and microalbuminuria. The association between metabolic uncontrolled diabetes mellitus was analyzed with the elevation of resistance index by χ(2) test or Fisher, being significant with a value of p < 0.05, and to assess the magnitude of the association that was measured with a response magnitude of 95%. 63 patients with type 2 diabetes were examined, with an average age of 52.3 ± 14.2 years, 41 were older than 50 years (65.0%), 26 with hypertension (41.2%), 32 with higher levels of glycated hemoglobin 7 (50.8%), 35 with normoalbuminuria (55.6%), 28 with microalbuminuria (44.4%), and 39 with a time evolution of diabetes of more than 10 years (61.9%). We observed a statistically significant difference between microalbuminuria and increased duration of diabetes mellitus with high resistance index. The alterations in renal microvasculature conditioned by the occurrence of microalbuminuria in diabetic nephropathy and the duration of diabetes are strongly associated with higher resistance index.

  14. An index of healing in below-knee amputation: leg blood pressure by Doppler ultrasound.

    PubMed

    Barnes, R W; Shanik, G D; Slaymaker, E E

    1976-01-01

    Preoperative Doppler ultrasonic assessment of below-knee (BK) arterial signals and systolic blood pressures was performed on 50 patients undergoing 53 BK amputations for advanced ischemia. No patient was excluded from initial BK amputation unless gangrene at that level or severe joint contracture was present. Failure of healing of the BK amputation occurred in all five limbs with an undetectable Doppler arterial signal (and thus pressure) below the knee. Failure of amputation occurred in four of 16 limbs with detectable arterial signals and BK pressures less than 70 mm. Hg. Healing occurred in all 32 limbs with BK pressures greater than 70 mm. Hg. The differences in healing between these three groups are highly significant (p less than 0.005). This study suggests that Doppler ultrasonic assessment of BK arterial signals and pressures may be a simple hemodynamic correlate of healing of a BK amputation. Absence of a detectable arterial signal below the knee may be an indication for initial above-knee (AK) amputation in advanced ischemia.

  15. Doppler echocardiography

    SciTech Connect

    Labovitz, A.J.; Williams, G.A.

    1988-01-01

    The authors are successful in presenting a basic book on clinical quantitative Doppler echocardiography. It is not intended to be a comprehensive text, but it does cover clinical applications in a succinct fashion. Only the more common diseases in the adult are considered. The subjects are presented logically and are easy to comprehend. The illustrations are good, and the book is paperbound. The basic principles of Doppler echocardiography are presented briefly. The book ends with chapters on left ventricular function (stroke volume and cardiac output), congenital heart disease, and color Doppler echo-cardiography. There are numerous references and a good glossary and index.

  16. Diagnostic role of new Doppler index in assessment of renal artery stenosis

    PubMed Central

    Chain, Sergio; Luciardi, Hector; Feldman, Gabriela; Berman, Sofia; Herrera, Ramón N; Ochoa, Javier; Muntaner, Juan; Escudero, Eduardo M; Ronderos, Ricardo

    2006-01-01

    Background Renal artery stenosis (RAS) is one of the main causes of secondary systemic arterial hypertension. Several non-invasive diagnostic methods for RAS have been used in hypertensive patients, such as color Doppler ultrasound (US). The aim of this study was to assess the sensitivity and specificity of a new renal Doppler US direct-method parameter: the renal-renal ratio (RRR), and compare with the sensitivity and specificity of direct-method conventional parameters: renal peak systolic velocity (RPSV) and renal aortic ratio (RAR), for the diagnosis of severe RAS. Methods Our study group included 34 patients with severe arterial hypertension (21 males and 13 females), mean age 54 (± 8.92) years old consecutively evaluated by renal color Doppler ultrasound (US) for significant RAS diagnosis. All of them underwent digital subtraction arteriography (DSA). RAS was significant if a diameter reduction > 50% was found. The parameters measured were: RPSV, RAR and RRR. The RRR was defined as the ratio between RPSV at the proximal or mid segment of the renal artery and RPSV measured at the distal segment of the renal artery. The sensitivity and specificity cutoff for the new RRR was calculated and compared with the sensitivity and specificity of RPSV and RAR. Results The accuracy of the direct method parameters for significant RAS were: RPSV >200 cm/s with 97% sensitivity, 72% specificity, 81% positive predictive value and 95% negative predictive value; RAR >3 with 77% sensitivity, 90% specificity, 90% positive predictive value and 76% negative predictive value. The optimal sensitivity and specificity cutoff for the new RRR was >2.7 with 97% sensitivity (p < 0.004) and 96% specificity (p < 0.02), with 97% positive predictive value and 97% negative predictive value. Conclusion The new RRR has improved specificity compared with the direct method conventional parameters (RPSV >200cm/s and RAR >3). Both RRR and RPSV show better sensitivity than RAR for the RAS diagnosis

  17. The (Pulsed-Wave) Doppler Fetal Myocardial Performance Index: Technical Challenges, Clinical Applications and Future Research.

    PubMed

    Mahajan, Aditi; Henry, Amanda; Meriki, Neama; Hernandez-Andrade, Edgar; Crispi, Fatima; Wu, Linda; Welsh, Alec W

    2015-01-01

    Functional cardiovascular assessment is becoming an increasingly important tool in the study of fetal pathology. The myocardial performance index (MPI) is a parameter measuring global myocardial function. Since its introduction, several studies have proposed methods to improve its reproducibility and have constructed normative reference ranges. Fetal heart evaluation using the MPI is technically challenging, requiring specific training and expertise, and a consensus has yet to be reached on the method of delineating the time periods used to calculate the index. Despite these limitations, it has been shown to be a useful and highly sensitive parameter of dysfunction in a number of fetal pathologies. Further research is warranted into the effect of pathology on MPI, parameters of unilateral cardiac strain that utilise MPI, and automation of the MPI to encourage incorporation of the MPI as a useful tool in clinical practice.

  18. [Comparitive [Comparative] study of the indexes of pulmonary arterial pressure of healthy children at different altitudes by Doppler echocardiography].

    PubMed

    Pang, Ying; Ma, Ru-Yan; Qi, Hai-Ying; Sun, Kun

    2004-08-01

    Reduced oxygen availability at a high altitude is associated with increased pulmonary arterial pressure (PAP). With the altitude goes up the change of PAP in healthy children is still not clear. The difference of PAP in native Tibetan and Han children at a high altitude are also not clear. Many studies have shown that Doppler echocardiographic estimation of PAP correlates closely to the values obtained with the invasive measurement. Therefore the indexes of PAP in health children living at different altitudes were investigated and the indexes of PAP in Han and Tibetan children at the high altitude were compared by Doppler echocardiography. A randomized survey was carried out on the indexes of PAP with Doppler echocardiography (HP-8500 and CAL-163 echocardiographic machine) by two doctors of Qinghai Provincial Women and Children Hospital from June 1998 to July 2002. The survey covering Jiuzhi Qinghai (at 3700 m above the sea level), Xining Qinghai (at 2260 m above the sea level) and Shanghai (at 16 m above the sea level) included a population of 1061 children aged 0 - 14 years. The population of 1061 composed of 218 Han children at Shanghai, 567 Han children at Xining Qinghai and 276 children at Jiuzhi, Qinghai including 118 migrated Han and 148 native Tibetan children. The physical, EKG and chest X-ray examination of each child were carried out to ensure all the subjects were healthy. A pulse oximeter was placed on each child's foot to provide measurements of arterial oxygen saturation (SO2) distal to the ductus arteriosus. The indexes of PAP included right ventricular systolic time interval (RSTI) and mean of pulmonary arterial pressure (mPAP) which was assessed by a multiple regression equation (mPAP=27.79 + 35.42 x PEP/AT-50.85 x AT/ETc). The AT/ETc was that AT/ET was divided by R-R. The RSTI included previous ejection period (PEP), ascending time (AT), ejection time (ET), PEP/AT and AT/ET. All subjects were divided into 7 age groups. The data of PAP indexes

  19. Transcranial Doppler ultrasound blood flow velocity and pulsatility index as systemic indicators for Alzheimer’s disease

    PubMed Central

    Roher, Alex E.; Garami, Zsolt; Tyas, Suzanne L.; Maarouf, Chera L.; Kokjohn, Tyler A.; Belohlavek, Marek; Vedders, Linda J.; Connor, Donald; Sabbagh, Marwan N.; Beach, Thomas G.; Emmerling, Mark R.

    2010-01-01

    Background Multiple lines of evidence suggest cardiovascular co-morbidities hasten the onset of Alzheimer’s disease (AD) or accelerate its course. Methods To evaluate the utility of cerebral vascular physical function/condition parameters as potential systemic indicators of AD, we employed transcranial Doppler (TCD) ultrasound to assess cerebral blood flow and vascular resistance of the 16 arterial segments comprising the circle of Willis and its major tributaries. Results Our study revealed decreased arterial mean flow velocity (MFV) and increased pulsatility index (PI) are associated with a clinical diagnosis of presumptive AD. Cerebral blood flow impairment revealed by these parameters reflects the global hemodynamic and structural consequences of a multifaceted disease process yielding diffuse congestive microvascular pathology, increased arterial rigidity, and decreased arterial compliance combined with putative age-associated cardiovascular output declines. Conclusions TCD evaluation offers direct physical confirmation of brain perfusion impairment and may ultimately provide a convenient, noninvasive means to assess the efficacy of medical interventions on cerebral blood flow or reveal incipient AD. In the near term, TCD-based direct assessments of brain perfusion may offer the prospect of preventing or mitigating AD simply by revealing patients who would benefit from interventions to improve circulatory system function. PMID:21388892

  20. Intrafamilial aggregation and heritability of tissue Doppler indexes of left ventricular diastolic function in a group of African descent.

    PubMed

    Peterson, Vernice R; Norton, Gavin R; Libhaber, Carlos D; Maseko, Muzi J; Sareli, Pinhas; Woodiwiss, Angela J

    2016-06-01

    Although several indexes of left ventricular (LV) diastolic function show heritability, the genetic influence on the tissue Doppler index, E/e' (early transmitral velocity/velocity of myocardial tissue lengthening), an index of LV filling pressures in those of black African descent is currently unknown. Furthermore, whether any genetic influences on E/e' are through an impact of LV remodeling or aortic function is unknown. Intrafamilial aggregation and heritability (SAGE software) of E/e' (echocardiography) were assessed in 129 nuclear families (29 spouse pairs, 216 parent-child pairs, and 113 sibling-sibling pairs) from an urban developing community of black Africans, independent of LV mass index (LVMI), LV relative wall thickness (RWT), central aortic systolic pressure (SBPc), and backward wave pressures (Pb) (applanation tonometry, SphygmoCor software). Independent of confounders including LVMI and RWT, E/e' was correlated in parent-child (r = 0.23; P < .001) and sibling-sibling (r = 0.29; P < .005), but not in spouse (r = 0.13; P = .51) pairs. The relationships between parent-child (r = 0.22; P < .001) and sibling-sibling (r = 0.29; P < .005) pairs persisted with adjustments for SBPc. The relationships between parent-child (r = 0.22; P < .001) and sibling-sibling (r = 0.26; P < .01) pairs also persisted with adjustments for Pb. Independent of confounders including LVMI and RWT, E/e' showed significant heritability (h(2) ± standard error of the mean [SEM] = 0.51 ± 0.11; P < .0001) which similarly persisted with adjustments for SBPc (h(2) ± SEM = 0.50 ± 0.11; P < .0001) and Pb (h(2) ± SEM = 0.49 ± 0.11; P < .0001). In conclusion, in a group of African ancestry, independent of LV remodeling and aortic function, E/e' shows significant intrafamilial aggregation and robust heritability. Hence, genetic factors may play an important role in determining moderate-to-severe LV diastolic dysfunction independent of

  1. XML, TEI, and Digital Libraries in the Humanities.

    ERIC Educational Resources Information Center

    Nellhaus, Tobin

    2001-01-01

    Describes the history and major features of XML and TEI, discusses their potential utility for the creation of digital libraries, and focuses on XML's application in the humanities, particularly theater and drama studies. Highlights include HTML and hyperlinks; the impact of XML on text encoding and document access; and XML and academic…

  2. Usefulness of tissue doppler and color M-mode indexes of left ventricular diastolic function in predicting outcomes in systolic left ventricular heart failure (from the ADEPT study).

    PubMed

    Troughton, Richard W; Prior, David L; Frampton, Christopher M; Nash, Patrick J; Pereira, Jeremy J; Martin, Maureen; Fogarty, Annette; Morehead, Annitta J; Starling, Randall C; Young, James B; Thomas, James D; Lauer, Michael S; Klein, Allan L

    2005-07-15

    The prognostic values of tissue Doppler imaging and color M-mode diastolic indexes were studied in 225 patients who had symptomatic systolic heart failure in the ADEPT study. The primary end point of death, transplantation, or hospitalization due to heart failure occurred in 65 patients and was independently predicted by shorter deceleration time, lower ratio of pulmonary vein systolic to diastolic velocity, and increasing levels of the ratios of early transmitral velocity to early annular velocity or velocity of propagation. For the ratio of early transmitral velocity to early annular velocity, this prediction was additive to deceleration time. Newer diastolic indexes provide an independent prediction of clinical outcomes.

  3. DOPPLER WEATHER SYSTEM

    SciTech Connect

    Berlin, Gary J.

    2002-08-05

    The SRS Doppler Weather System consists of a Doppler Server, A Master Server (also known as the Weather Server), several Doppler Slave Servers, and client-side software program called the Doppler Radar Client. This system is used to display near rel-time images taken from the SRS Weather Center's Doppler Radar computer. The Doppler Server is software that resides on the SRS Doppler Computer. It gathers raw data, 24-bit color weather images via screen scraping ever five minutes as requested by the Master Server. The Doppler Server then reduces the 24-bit color images to 8-bit color using a fixed color table for analysis and compression. This preserves the fidelity of the image color and arranges the colors in specific order for display. At the time of color reduction, the white color used for the city names on the background images are remapped to a different index (color) of white that the white on the weather scale. The Weather Server places a time stamp on the image, then compresses the image and passes it to all Doppler Slave servers. Each of the Doppler Slave servers mainitain a circular buffer of the eight most current images representing the last 40 minutes of weather data. As a new image is added, the oldest drops off. The Doppler Radar Client is an optional install program for any site-wide workstation. When a Client session is started, the Client requests Doppler Slave server assignment from the Master Server. Upon its initial request to the Slave Server, the Client obtains all eight current images and maintains its own circular buffer, updating its images every five minutes as the Doppler Slave is updated. Three background reference images are stored as part of the Client. The Client brings up the appropriate background image, decompresses the doppler data, and displays the doppler data on the background image.

  4. Comparison of esophageal Doppler and plethysmographic variability index to guide intraoperative fluid therapy for low-risk patients undergoing colorectal surgery.

    PubMed

    Warnakulasuriya, Samantha R; Davies, Simon J; Wilson, R Jonathan T; Yates, David R A

    2016-11-01

    This study aims to investigate if there is equivalence in volumes of fluid administered when intravenous fluid therapy is guided by Pleth Variability Index (PVI) compared to the established technology of esophageal Doppler in low-risk patients undergoing major colorectal surgery. Randomized controlled trial. Operating room. Forty low-risk patients undergoing elective colorectal surgery. Patients were monitored by esophageal Doppler and PVI probes and were randomized to have fluid therapy directed by using one of these technologies, with 250 mL boluses of colloid to maintain a maximal stroke volume, or a PVI of less than 14%. Absolute volumes of fluid volumes given intraoperatively were measured as were 24 hours fluid volumes. Perioperative measurements of lactate and base excess were recorded as were postoperative complications. There was no significant difference between PVI and esophageal Doppler groups in mean total fluid administered (1286 vs 1520 mL, P=.300) or mean intraoperative fluid balance (+839 v+1145 mL, P=.150). PVI offers an entirely non-invasive alternative for goal-directed fluid therapy in this group of patients. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Concordance between automated oscillometric measurement of ankle-brachial index and traditional measurement by eco-Doppler in patients without peripheral artery disease.

    PubMed

    Rodriguez-Roca, Gustavo C; Villarín-Castro, Alejandro; Carrasco-Flores, Javier; Artigao-Rodenas, Luis M; Carbayo-Herencia, Julio A; Escobar-Cervantes, Carlos; Alonso-Moreno, Francisco J; Segura-Fragoso, Antonio; Gómez-Serranillos, Manuel; Hernández-Moreno, Julio

    2014-10-01

    To evaluate the concordance between automated oscillometric measurement (WatchBP® Office ABI) of the ankle- brachial index (ABI) and the traditional measurement by eco-Doppler in a Spanish population without peripheral artery disease attended in primary care. The ABI was determined by both methods in a general population aged ≥ 18 years, from the RICARTO study. The intraclass correlation coefficient was calculated to assess the concordance between both techniques and the Bland-Altman plot was determined to analyze the agreement between them. A total of 322 subjects (mean age 47.7 ± 16.0 years; 54.3% women) were included in the study. With regard to cardiovascular risk factors, 70.5% of subjects had dyslipidemia, 26.7% hypertension, 24.8% obesity, 8.4% diabetes and 25.5% were smokers. Mean ABI measured by eco-Doppler and the automated method were 1.17 ± 0.1 and 1.2 ± 0.1, respectively (mean differences - 0.03 ± 0.09; p < 0.001). The Pearson correlation coefficient and the intraclass correlation coefficient were in both cases 0.70. The automated oscillometric measurement of ABI is a reliable and useful alternative to conventional eco-Doppler determination in the general population without peripheral artery disease attended in primary care.

  6. Color M-mode Doppler flow propagation velocity is a preload insensitive index of left ventricular relaxation: animal and human validation

    NASA Technical Reports Server (NTRS)

    Garcia, M. J.; Smedira, N. G.; Greenberg, N. L.; Main, M.; Firstenberg, M. S.; Odabashian, J.; Thomas, J. D.

    2000-01-01

    OBJECTIVES: To determine the effect of preload in color M-mode Doppler flow propagation velocity (v(p)). BACKGROUND: The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode v(p) has been proposed as a new index of LV relaxation. METHODS: We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak velocity during early filling (E) and v(p) were extracted by digital analysis of color M-mode Doppler images. RESULTS: In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p < 0.001). Peak early filling (E) velocity decreased in animals from 56 +/- 21 to 42 +/- 17 cm/s (p < 0.001) without change in v(p) (from 35 +/- 15 to 35 +/- 16, p = 0.99). Results were similar in humans (from 69 +/- 15 to 53 +/- 22 cm/s, p < 0.001, and 37 +/- 12 to 34 +/- 16, p = 0.30). In both species, there was a strong correlation between LV relaxation (tau) and v(p) (r = 0.78, p < 0.001, r = 0.86, p < 0.001). CONCLUSIONS: Our results indicate that color M-mode Doppler v(p) is not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.

  7. Color M-mode Doppler flow propagation velocity is a preload insensitive index of left ventricular relaxation: animal and human validation

    NASA Technical Reports Server (NTRS)

    Garcia, M. J.; Smedira, N. G.; Greenberg, N. L.; Main, M.; Firstenberg, M. S.; Odabashian, J.; Thomas, J. D.

    2000-01-01

    OBJECTIVES: To determine the effect of preload in color M-mode Doppler flow propagation velocity (v(p)). BACKGROUND: The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode v(p) has been proposed as a new index of LV relaxation. METHODS: We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak velocity during early filling (E) and v(p) were extracted by digital analysis of color M-mode Doppler images. RESULTS: In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p < 0.001). Peak early filling (E) velocity decreased in animals from 56 +/- 21 to 42 +/- 17 cm/s (p < 0.001) without change in v(p) (from 35 +/- 15 to 35 +/- 16, p = 0.99). Results were similar in humans (from 69 +/- 15 to 53 +/- 22 cm/s, p < 0.001, and 37 +/- 12 to 34 +/- 16, p = 0.30). In both species, there was a strong correlation between LV relaxation (tau) and v(p) (r = 0.78, p < 0.001, r = 0.86, p < 0.001). CONCLUSIONS: Our results indicate that color M-mode Doppler v(p) is not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.

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

    NASA Technical Reports Server (NTRS)

    Hamilton, D. R.; Sargsyan, A. E.; Fincke, E. M.; Magnus, S. H.; Lonchakov, Y. V.; Alferova, I. V.; Dulchavsky, S. A.; Ebert, D.; Garcia, K.; Martin, D.; hide

    2009-01-01

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

  9. Determinants and Regression Equations for the Calculation of z Scores of Left Ventricular Tissue Doppler Longitudinal Indexes in a Healthy Italian Pediatric Population.

    PubMed

    Fibbi, Veronica; Ballo, Piercarlo; Favilli, Silvia; Spaziani, Gaia; Calabri, Giovanni B; Pollini, Iva; Zuppiroli, Alfredo; Chiappa, Enrico

    2015-01-01

    Aim. We investigated the predictors of tissue Doppler left ventricular (LV) longitudinal indexes in a healthy Italian pediatric population and established normative data and regression equations for the calculation of z scores. Methods and Results. A total of 369 healthy subjects aged 1-17 years (age of 6.4 ± 1.1 years, 49.1% female) underwent echocardiography. LV peak longitudinal velocity at systole (s (')), early diastole (e (')), and late diastole (a (')) was determined by tissue Doppler. The ratio of peak early diastolic LV filling velocity to e (') was calculated. Age was the only independent determinant of s (') (β = 0.491, p < 0.0001) and the strongest determinant of e (') (β = 0.334, p < 0.0001) and E/e (') (β = -0.369, p < 0.0001). Heart rate was the main determinant of a (') (β = 0.265, p < 0.0001). Male gender showed no effects except for a weak association with lateral s ('), suggesting no need of gender-specific reference ranges. Age-specific reference ranges, regression equations, and scatterplots for the calculation of z scores were determined for each index. Conclusion. In a pediatric Italian population, age was the strongest determinant of LV longitudinal dynamics. The availability of age-specific normality data for the calculation of z scores may allow for correctly detecting LV dysfunction in pediatric pathological populations.

  10. Determinants and Regression Equations for the Calculation of z Scores of Left Ventricular Tissue Doppler Longitudinal Indexes in a Healthy Italian Pediatric Population

    PubMed Central

    Fibbi, Veronica; Ballo, Piercarlo; Spaziani, Gaia; Calabri, Giovanni B.; Pollini, Iva; Zuppiroli, Alfredo; Chiappa, Enrico

    2015-01-01

    Aim. We investigated the predictors of tissue Doppler left ventricular (LV) longitudinal indexes in a healthy Italian pediatric population and established normative data and regression equations for the calculation of z scores. Methods and Results. A total of 369 healthy subjects aged 1–17 years (age of 6.4 ± 1.1 years, 49.1% female) underwent echocardiography. LV peak longitudinal velocity at systole (s'), early diastole (e'), and late diastole (a') was determined by tissue Doppler. The ratio of peak early diastolic LV filling velocity to e' was calculated. Age was the only independent determinant of s' (β = 0.491, p < 0.0001) and the strongest determinant of e' (β = 0.334, p < 0.0001) and E/e' (β = −0.369, p < 0.0001). Heart rate was the main determinant of a' (β = 0.265, p < 0.0001). Male gender showed no effects except for a weak association with lateral s', suggesting no need of gender-specific reference ranges. Age-specific reference ranges, regression equations, and scatterplots for the calculation of z scores were determined for each index. Conclusion. In a pediatric Italian population, age was the strongest determinant of LV longitudinal dynamics. The availability of age-specific normality data for the calculation of z scores may allow for correctly detecting LV dysfunction in pediatric pathological populations. PMID:26759729

  11. Analysis of index modulation in microembolic Doppler signals part I: radiation force as a new hypothesis-simulations.

    PubMed

    Girault, Jean-Marc; Kouamé, Denis; Ménigot, Sébastien; Souchon, Grégrory; Tranquart, François

    2011-01-01

    The purpose of this study was to reveal the cause of frequency modulation (FM) present in microembolic Doppler ultrasound signals. This novel explanation should help the development of sensitive microembolus discrimination techniques. We suggest that the frequency modulation detected is caused by the ultrasonic radiation force (URF) acting directly on microemboli. The frequency modulation and the imposed displacement were calculated using a numerical dynamic model. By setting simulation parameters with practical values, it was possible to reproduce most microembolic frequency modulation signatures. The most interesting findings in this study were that: (1) the ultrasound radiation force acting on a gaseous microembolus and its corresponding cumulative displacement were far higher than those obtained for a solid microembolus, and that is encouraging for discrimination purposes; and 2) the calculated frequency modulation indices (FMIs) (≈20 kHz) were in good agreement with literature results. By taking into account the URF, the flow pulsatility, the beam-to-flow angle and both the velocity and the ultrasound beam profiles, it was possible to explain all erratic FM signatures of a microbubble. Finally, by measuring FMI from simulated Doppler signals and by using a constant threshold of 1 KHz, it was possible to discriminate gaseous from solid microemboli with ease. Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  12. Hyperhomocysteinemia as an Early Predictor of Erectile Dysfunction: International Index of Erectile Function (IIEF) and Penile Doppler Ultrasound Correlation With Plasma Levels of Homocysteine.

    PubMed

    Giovannone, Riccardo; Busetto, Gian Maria; Antonini, Gabriele; De Cobelli, Ottavio; Ferro, Matteo; Tricarico, Stefano; Del Giudice, Francesco; Ragonesi, Giulia; Conti, Simon L; Lucarelli, Giuseppe; Gentile, Vincenzo; De Berardinis, Ettore

    2015-09-01

    Erectile dysfunction (ED) is inability to achieve and maintain an erection to permit satisfactory sexual activity. Homocysteine (Hcys) is a sulfur-containing amino acid synthesized from the essential amino acid methionine. Experimental models have elucidated the role of hyperhomocysteinemia (HHcys) as a strong and independent predictor for atherosclerosis progression and impaired cavernosal perfusion. The aim of this study is to investigate the serum levels of Hcys in our cohort of patients with ED, to compare these values with these of control population and to examine Hcys as a predictive marker for those patients who are beginning to complain mild-moderate ED. A total of 431 patients were enrolled in the study. The whole cohort was asked to complete the International Index of Erectile Function (IIEF) questionnaire. The study population was divided in 3 main groups: Group A: 145 patients with no ED serving as a control group; Group B: 145 patients with mild or mild-moderate ED; Group C: 141 patients with moderate or severe ED. Each participant underwent blood analysis. All patients underwent baseline and dynamic penile Doppler ultrasonography. We found in our cohort mean Hcys plasma concentrations significantly higher than the cut-off point in both groups B and C (18.6 ± 4.7 and 28.38 ± 7.8, respectively). Mean IIEF score was 27.9 ± 1.39, 19.5 ± 2.6, and 11.1 ± 2.5 for groups A, B, and C, respectively (P < 0.0001). In the penile Doppler ultrasonography studies, a high significant inverse correlation was detected between the mean values of the 10th minute's peak-systolic velocity (PSV) and Hcys levels for the groups B and C. This establishes a dose-dependent association between Hcys and ED. Furthermore, we showed that Hcys was an earlier predictor of ED than Doppler studies, as the Hcys increase was present in patients with mild ED even before abnormal Doppler values.

  13. Between-day reliability of local thermal hyperaemia in the forearm and index finger using single point laser-Doppler flowmetry.

    PubMed

    McGarr, Gregory W; Hodges, Gary J; Cheung, Stephen S

    2017-08-12

    To assess between-day reliability for local thermal hyperaemia (LTH) in glabrous and non-glabrous index finger skin and non-glabrous forearm skin, with single point laser-Doppler flowmetry. Part-1: In healthy, habitually active males (n=10), LTH was examined twice (~7-10 d apart) for both skin types on the index finger. Part-2: Identical testing was performed on the volar forearm. Local heating (33-42°C at 1°C·20 s(-1) +20 min at 44°C) was performed at all skin sites and baseline, initial peak, and plateau phases were identified. Data were expressed as raw cutaneous vascular conductance (CVC; laser-Doppler flux/mean arterial pressure), and as CVC normalized to baseline (%CVC33°C ) and maximum heating (%CVC44°C ). Reliability was assessed using between-day mean difference, coefficient of variation (%CV), and intra-class correlation coefficient. Reliability (%CV) was poor at baseline for all forms of data presentation and for other phases with %CVC33°C . At the initial peak and plateau, reliability was moderate-poor (20-26%) for CVC and good-moderate (6-18%) for %CVC44°C . Reliability was good-moderate for vasodilatory onset time (10-23%) and time to initial peak (6-13%). For all sites, LTH reliability was acceptable for the timing, and for the initial peak and plateau using CVC or %CVC44°C . This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  14. Relative indexes of cutaneous blood perfusion measured by real-time laser Doppler imaging (LDI) in healthy volunteers.

    PubMed

    Seyed Jafari, S Morteza; Schawkat, Megir; Van De Ville, Dimitri; Shafighi, Maziar

    2014-07-01

    We used real-time LDI to study regional variations in microcirculatory perfusion in healthy candidates to establish a new methodology for global perfusion body mapping that is based on intra-individual perfusion index ratios. Our study included 74 (37 female) healthy volunteers aged between 22 and 30 years (mean 24.49). Imaging was performed using a recent microcirculation-imaging camera (EasyLDI) for different body regions of each volunteer. The perfusion values were reported in Arbitrary Perfusion Units (APU). The relative perfusion indexes for each candidate's body region were then obtained by normalization with the perfusion value of the forehead. Basic parameters such as weight, height, and blood pressure were also measured and analyzed. The highest mean perfusion value was reported in the forehead area (259.21APU). Mean perfusion in the measured parts of the body correlated positively with mean forehead value, while there was no significant correlation between forehead blood perfusion values and room temperature, BMI, systolic blood pressure and diastolic blood pressure (p=0.420, 0.623, 0.488, 0.099, respectively). Analysis of the data showed that perfusion indexes were not significantly different between male and female volunteers except for the ventral upper arm area (p=.001). LDI is a non-invasive, fast technique that opens several avenues for clinical applications. The mean perfusion indexes are useful in clinical practice for monitoring patients before and after surgical interventions. Perfusion values can be predicted for different body parts for patients only by taking the forehead perfusion value and using the perfusion index ratios to obtain expected normative perfusion values. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Doppler and the Doppler Effect.

    DTIC Science & Technology

    1984-06-01

    Doppler Applications Doppler Effect Roemer Doppler Principle Bradley Relative motion Velocity History Light Velocity 20. ABSTRACT (Continue on reverse...of Colorado, Boulder, CO 11-14 Jan 1984 5 1. Historical Background The astronomer Olaf Roemer determined the velocity of light in 1676 from time...approached Jupiter and longer when it receded from Jupiter. In effect, Roemer used a Doppler method in determining the velocity of light . [2 ] In 1727

  16. Right Pulmonary Artery Distensibility Index (RPAD Index). A field study of an echocardiographic method to detect early development of pulmonary hypertension and its severity even in the absence of regurgitant jets for Doppler evaluation in heartworm-infected dogs.

    PubMed

    Venco, Luigi; Mihaylova, Liliya; Boon, June A

    2014-11-15

    Despite the term "heartworm disease" Dirofilaria immitis infection in dogs should be considered a pulmonary arterial disease that might only involve the right heart structures in its late stage. Chronic infection by adult heartworms in dogs results in proliferative endoarteritis leading to progressively increasing pulmonary artery pressure due to reduced elasticity. Elasticity allows the pulmonary arteries to stretch in response to each pulse and helps maintain a relatively constant pressure in the arteries despite the pulsating nature of the blood flow. Pulmonary artery distensibility for both acute and chronic pulmonary hypertension has been investigated in humans using MRI and has been correlated with the severity of hypertension and its outcome and treatment response. The aim of the present study was to investigate whether echocardiographic measurement of the percentage change in diameter of the right pulmonary artery in systole and diastole (distensibility) may be of value in assessing the presence and severity of pulmonary hypertension in heartworm-infected dogs. The Right Pulmonary Artery Distensibility Index (RPAD Index) (which is calculated as the difference in diameter of the right pulmonary artery in systole and diastole) was calculated in healthy and naturally infected heartworm-positive dogs. The right pulmonary artery was chosen because it is usually affected earlier and to a greater degree. Data were obtained from healthy heartworm-free dogs without any clinical, radiographic, or echocardiographic signs of pulmonary hypertension; naturally infected heartworm-positive dogs in different stages of the disease in which pulmonary pressure could be measured by Doppler echocardiography (using tricuspid and or pulmonary regurgitation velocity and pressure gradient); and naturally infected heartworm-positive dogs in different stages of the disease (with or without tricuspid and or pulmonary regurgitation) in which the pulmonary pressure was measured

  17. Color Doppler Sonographic Evaluation of Peak Systolic Velocity and Pulsatility Index in Artery after Pulsed HIFU Exposure

    NASA Astrophysics Data System (ADS)

    Yang, Feng-Yi; Chiu, Wei-Hsiu; Yeh, Chi-Fang

    2011-09-01

    The objective of current study was to investigate the functional changes in arteries induced by pulsed-HIFU with or without microbubbles. Sonication was applied at an ultrasound frequency of 1 MHz with a burst length of 50 ms and a repetition frequency of 1 Hz. The duration of the whole sonication was 6s. The abdominal aortas of Sprague-Dawley rats were surgically exposed and sonicated with pulsed HIFU; the pulsed HIFU beam was aimed using color images of the blood flow. There was no obvious normalized peak systolic velocity (PSV) change at various acoustic powers of pulsed-HIFU exposure in the absence of ultrasound contrast agent (UCA). However, the normalized PSV change induced by pulsed-HIFU decreased with the injected dose of UCA at acoustic powers. At this time, the normalized pulsatility index (PI) change in the vessel subjected to pulsed-HIFU increased in proportion to UCA dose. Additional research is needed to investigate the detailed mechanical effects of pulsed-HIFU exposure on blood flow and the structure of vessel walls.

  18. Non-invasive vascular assessment in the foot with diabetes: sensitivity and specificity of the ankle brachial index, toe brachial index and continuous wave Doppler for detecting peripheral arterial disease.

    PubMed

    Tehan, Peta Ellen; Bray, Alan; Chuter, Vivienne Helaine

    2016-01-01

    Non-invasive lower limb vascular assessment in people at risk of peripheral arterial disease (PAD) including those with diabetes is crucial. There is evidence that standard assessment techniques such as the ankle-brachial index (ABI) may be less effective in people with diabetes. However there is limited evidence for other frequently used tests including continuous wave Doppler (CWD), and the toe-brachial index (TBI). The aim of this study was to determine the sensitivity and specificity of, ABI, CWD and TBI in a population with, and without diabetes. Participants with and without diabetes who met current guidelines for vascular screening were recruited, and CWD waveforms, an ABI and a TBI were obtained from the right lower limb. Diagnostic accuracy was determined using colour duplex ultrasound (CFDU). Receiver operating characteristic curves were calculated. 117 participants were recruited, seventy-two with diabetes and forty-five without diabetes. CWD had the highest sensitivity in people with diabetes (74%) and without (84%). CWD also had the highest specificity in people with diabetes (74%) and without (84%) compared to both TBI and ABI. In participants with diabetes, the ABI was a poor test, area under the curve: 0.58 (p=0.27). CWD waveform is more likely to detect significant PAD compared to ABI and TBI in people with and without diabetes. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. How can we predict ureteral obstruction after gynecological surgery? The changes in Doppler resistive index and plasma creatinine and magnesium concentrations after surgical, unilateral ureteral obstruction in a rabbit model.

    PubMed

    Terek, M C; Tamsel, S; Aygul, S; Akman, L; Irer, S V; Itil, I M; Alper, G

    2006-01-01

    The aim of this study is to evaluate the changes in Doppler resistive index (RI) and plasma creatinine and magnesium concentrations after unilateral ureteral obstruction in a rabbit model. Fourteen adult female rabbits were used in this study. In seven rabbits, the left ureter was ligated with silk suture, and the control group was sham operated. Before surgery and on the second and seventh days after surgery, blood samples were obtained to measure plasma creatinine and magnesium concentrations. Doppler RIs of both kidneys were also measured before surgery and on the second and seventh days after the surgical procedure. With regard to magnesium levels, there was a significant within-subjects sessions difference [F(2, 20) = 15.21, P= 0.001] indicating a decrease through sessions. Magnesium concentrations decreased significantly at the postoperative second and seventh days compared to preoperative baseline levels (P= 0.003 and P= 0.001, respectively). Multifactorial analysis of variance was applied for each session separately with laterality, and groups as factors. The Doppler RI and the creatinine level did not show any significant differences or interactions for all sessions (P > 0.05). The decreasing plasma magnesium concentration after surgery may indicate ureteral injury; however, Doppler studies and creatinine levels may not be useful as well.

  20. Strengthening the University-Industry Relationship: A Case Study of the Electronics Department, TEI Crete

    ERIC Educational Resources Information Center

    Liodakis, George; Vardiambasis, Ioannis O.; Kartsonakis, Evangelos; Kaliakatsos, Ioannis A.

    2012-01-01

    The Department of Electronics of the Technological Educational Institute of Crete (DoE/TEI Crete) enjoys good approval ratings from the market and its graduates have a high rate of employability. However, survey data collected over the last ten years from graduates and from the enterprises in which they have been employed, or have carried out…

  1. Strengthening the University-Industry Relationship: A Case Study of the Electronics Department, TEI Crete

    ERIC Educational Resources Information Center

    Liodakis, George; Vardiambasis, Ioannis O.; Kartsonakis, Evangelos; Kaliakatsos, Ioannis A.

    2012-01-01

    The Department of Electronics of the Technological Educational Institute of Crete (DoE/TEI Crete) enjoys good approval ratings from the market and its graduates have a high rate of employability. However, survey data collected over the last ten years from graduates and from the enterprises in which they have been employed, or have carried out…

  2. Optimal Finite-Thrust Trans-earth Injection (TEI) Maneuvers for a Low Lunar Orbit (LLO) Earth Return Mission

    DTIC Science & Technology

    2010-12-01

    THRUST TRANS- EARTH INJECTION (TEI) MANEUVERS FOR A LOW LUNAR ORBIT (LLO) EARTH RETURN MISSION by Omar J. Wheatley December 2010 Thesis Co...2010 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Optimal Finite-Thrust Trans- earth Injection (TEI) Maneuvers for a Low...Lunar Orbit (LLO) Earth Return Mission 6. AUTHOR(S) Wheatley, Omar J. 5. FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval

  3. Assessment of the Utility of the Septal E/(E′ × S′) Ratio and Tissue Doppler Index in Predicting Left Ventricular Remodeling after Acute Myocardial Infarction

    PubMed Central

    Kenar Tiryakioglu, Selma; Yalin, Kıvanc; Coskun, Senol

    2016-01-01

    Background. The aim of this study is to show whether the septal E/(E′ × S′) ratio assessed by tissue Doppler echocardiography can predict left ventricular remodeling after first ST segment elevation myocardial infarction treated successfully with primary percutaneous intervention. Methods. Consecutive patients (n = 111) presenting with acute anterior myocardial infarction for the first time in their life were enrolled. All patients underwent successful primary percutaneous coronary intervention. Standard and tissue Doppler echocardiography were performed in the first 24-36 hours of admission. Echocardiographic examination was repeated after 6 months to reassess left ventricular volumes. Septal E/(E′ × S′) ratio was assessed by pulsed Doppler echocardiography. Results. Group 1 consisted of 33 patients with left ventricular (LV) remodeling, and Group 2 had 78 patients without LV remodeling. E/(E′ × S′) was significantly higher in Group 1 (4.1 ± 1.9 versus 1.65 ± 1.32, p = 0.001). The optimal cutoff value for E/(E′ × S′) ratio was 2.34 with 87.0% sensitivity and 82.1% specificity. Conclusion. Septal E/(E′ × S′) values measured after the acute anterior myocardial infarction can strongly predict LV remodeling in the 6-month follow-up. In the risk assessment, the septal E/(E′ × S′) can be evaluated together with the conventional echocardiographic techniques. PMID:27703973

  4. The Assessment and Potential Implications of the Myocardial Performance Index Post Exercise in an at Risk Population

    PubMed Central

    Ruisi, Michael; Levine, Michael; Finkielstein, Dennis

    2013-01-01

    Background The myocardial performance index (MPI) first described by Chuwa Tei in 1995 is a relatively new echocardiographic variable used for assessment of overall cardiac function. Previous studies have demonstrated the MPI to be a sum representation of both left ventricular systolic and diastolic function with prognostic value in patients with coronary artery disease as well as symptomatic heart failure. Methods Ninety patients with either established coronary artery disease (CAD) or CAD risk factors underwent routine treadmill exercise stress testing with two-dimensional Doppler echocardiography using the standard Bruce protocol. Both resting and stress MPI values were measured for all 90 of the patients. Results Using a normal MPI cut off of ≤ 0.47, the prevalence of an abnormal resting MPI in our 90 subjects was 72/90 or 80% and the prevalence of an abnormal stress MPI in our 90 subjects was 48/90 or 53.33%. The average MPI observed in the resting portion of the stress test for the cohort was: 0.636 with a standard deviation of 0.182. The average MPI in the stress portion of the stress test for the cohort was 0.530 with a standard deviation of 0.250. The P value with the use of a one-tailed dependent T test was calculated to be < 0.05. Conclusion We postulate that these findings reflect that the MPI (Tei) index assessed during exercise may be a sensitive indicator of occult coronary disease in an at risk group independent of wall motion assessment.

  5. Observation of the Zero Doppler Effect.

    PubMed

    Ran, Jia; Zhang, Yewen; Chen, Xiaodong; Fang, Kai; Zhao, Junfei; Chen, Hong

    2016-04-05

    The normal Doppler effect has well-established applications in many areas of science and technology. Recently, a few experimental demonstrations of the inverse Doppler effect have begun to appear in negative-index metamaterials. Here we report an experimental observation of the zero Doppler effect, that is, no frequency shift irrespective of the relative motion between the wave signal source and the detector in a zero-index metamaterial. This unique phenomenon, accompanied by the normal and inverse Doppler effects, is generated by reflecting a wave from a moving discontinuity in a composite right/left-handed transmission line loaded with varactors when operating in the near zero-index passband, or the right/left-handed passband. This work has revealed a complete picture of the Doppler effect in metamaterials and may lead to potential applications in electromagnetic wave related metrology.

  6. Observation of the Zero Doppler Effect

    PubMed Central

    Ran, Jia; Zhang, Yewen; Chen, Xiaodong; Fang, Kai; Zhao, Junfei; Chen, Hong

    2016-01-01

    The normal Doppler effect has well-established applications in many areas of science and technology. Recently, a few experimental demonstrations of the inverse Doppler effect have begun to appear in negative-index metamaterials. Here we report an experimental observation of the zero Doppler effect, that is, no frequency shift irrespective of the relative motion between the wave signal source and the detector in a zero-index metamaterial. This unique phenomenon, accompanied by the normal and inverse Doppler effects, is generated by reflecting a wave from a moving discontinuity in a composite right/left-handed transmission line loaded with varactors when operating in the near zero-index passband, or the right/left-handed passband. This work has revealed a complete picture of the Doppler effect in metamaterials and may lead to potential applications in electromagnetic wave related metrology. PMID:27046395

  7. Mirror-symmetry protected non-TRIM surface state in the weak topological insulator Bi2TeI

    NASA Astrophysics Data System (ADS)

    Rusinov, I. P.; Menshchikova, T. V.; Isaeva, A.; Eremeev, S. V.; Koroteev, Yu. M.; Vergniory, M. G.; Echenique, P. M.; Chulkov, E. V.

    2016-02-01

    Strong topological insulators (TIs) support topological surfaces states on any crystal surface. In contrast, a weak, time-reversal-symmetry-driven TI with at least one non-zero v1, v2, v3 ℤ2 index should host spin-locked topological surface states on the surfaces that are not parallel to the crystal plane with Miller indices (v1 v2 v3). On the other hand, mirror symmetry can protect an even number of topological states on the surfaces that are perpendicular to a mirror plane. Various symmetries in a bulk material with a band inversion can independently preordain distinct crystal planes for realization of topological states. Here we demonstrate the first instance of coexistence of both phenomena in the weak 3D TI Bi2TeI which (v1 v2 v3) surface hosts a gapless spin-split surface state protected by the crystal mirror-symmetry. The observed topological state has an even number of crossing points in the directions of the 2D Brillouin zone due to a non-TRIM bulk-band inversion. Our findings shed light on hitherto uncharted features of the electronic structure of weak topological insulators and open up new vistas for applications of these materials in spintronics.

  8. Mirror-symmetry protected non-TRIM surface state in the weak topological insulator Bi2TeI

    PubMed Central

    Rusinov, I. P.; Menshchikova, T. V.; Isaeva, A.; Eremeev, S. V.; Koroteev, Yu. M.; Vergniory, M. G.; Echenique, P. M.; Chulkov, E. V.

    2016-01-01

    Strong topological insulators (TIs) support topological surfaces states on any crystal surface. In contrast, a weak, time-reversal-symmetry-driven TI with at least one non-zero v1, v2, v3 ℤ2 index should host spin-locked topological surface states on the surfaces that are not parallel to the crystal plane with Miller indices (v1 v2 v3). On the other hand, mirror symmetry can protect an even number of topological states on the surfaces that are perpendicular to a mirror plane. Various symmetries in a bulk material with a band inversion can independently preordain distinct crystal planes for realization of topological states. Here we demonstrate the first instance of coexistence of both phenomena in the weak 3D TI Bi2TeI which (v1 v2 v3) surface hosts a gapless spin-split surface state protected by the crystal mirror-symmetry. The observed topological state has an even number of crossing points in the directions of the 2D Brillouin zone due to a non-TRIM bulk-band inversion. Our findings shed light on hitherto uncharted features of the electronic structure of weak topological insulators and open up new vistas for applications of these materials in spintronics. PMID:26864814

  9. Comparison of transvaginal color Doppler imaging and color Doppler energy for assessment of intraovarian blood flow.

    PubMed

    Tailor, A; Jurkovic, D; Bourne, T H; Natucci, M; Collins, W P; Campbell, S

    1998-04-01

    To investigate any systematic differences in the analysis of blood flow velocity waveforms derived by color Doppler imaging and color Doppler energy examination of corpora lutea and adnexal tumors, to test whether the accuracy for diagnosing ovarian malignancy differs between end points derived by color Doppler imaging and color Doppler energy, and to compare the reproducibility of flow velocity waveform analysis obtained by both methods. Fifty-six asymptomatic women with presumed corpora lutea and 67 women with known adnexal masses were included in the study. They all were examined using transvaginal sonography with color Doppler imaging and color Doppler energy. Pulsed Doppler sonography was used to obtain flow velocity waveforms to determine the pulsatility index (PI), resistance index (RI), peak systolic velocity, and time-averaged maximum velocity. The tumors were classified retrospectively according to histologic criteria. There were 52 women with benign, three with borderline, and 12 with malignant ovarian tumors. Repeated-measures analysis of variance revealed no systematic differences in the values of all four measurements performed under color Doppler imaging and color Doppler energy for all cases of corpora lutea and adnexal tumors (PI: P=.153, RI: P=.197, peak systolic velocity: P=.355, time-averaged maximum velocity: P=.159). All cases of borderline and malignant tumors had detectable pulsatile blood flow with color Doppler imaging and color Doppler energy. Forty-two (80.8%) of the benign tumors had flow detectable with color Doppler imaging, compared with 40 (76.9%) with color Doppler energy (P=.480). Analysis of receiver operating characteristic curves showed a marginal but nonsignificant improvement in diagnostic performance with color Doppler energy compared with color Doppler imaging for all four measurements (PI: P=.182, RI: P=.178, peak systolic velocity: P=.254, time-averaged maximum velocity: P=.238). The intraclass correlation coefficients

  10. SU-E-I-27: Establishing Target Exposure Index Values for Computed Radiography

    SciTech Connect

    Murphy, N; Tchou, P; Belcher, K; Scott, A

    2014-06-01

    Purpose: To develop a standard set of target exposure index (TEI) values to be applied to Agfa Computed Radiography (CR) readers in accordance with International Electrotechnical Committee 62494-1 (ed. 1.0). Methods: A large data cohort was collected from six USAF Medical Treatment Facilities that exclusively use Agfa CR Readers. Dose monitoring statistics were collected from each reader. The data was analyzed based on anatomic region, view, and processing speed class. The Agfa specific exposure metric, logarithmic mean (LGM), was converted to exposure index (EI) for each data set. The optimum TEI value was determined by minimizing the number of studies that fell outside the acceptable deviation index (DI) range of +/− 2 for phototimed techniques or a range of +/−3 for fixed techniques. An anthropomorphic radiographic phantom was used to corroborate the TEI recommendations. Images were acquired of several anatomic regions and views using standard techniques. The images were then evaluated by two radiologists as either acceptable or unacceptable. The acceptable image with the lowest exposure and EI value was compared to the recommended TEI values using a passing DI range. Results: Target EI values were determined for a comprehensive list of anatomic regions and views. Conclusion: Target EI values must be established on each CR unit in order to provide a positive feedback system for the technologist. This system will serve as a mechanism to prevent under or overexposures of patients. The TEI recommendations are a first attempt at a large scale process improvement with the goal of setting reasonable and standardized TEI values. The implementation and effectiveness of the recommended TEI values should be monitored and adjustments made as necessary.

  11. Doppler flowmeter

    DOEpatents

    Karplus, Henry H. B.; Raptis, Apostolos C.

    1983-01-01

    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.

  12. Doppler flowmeter

    DOEpatents

    Karplus, H.H.B.; Raptis, A.C.

    1981-11-13

    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.

  13. An accelerometer based system to measure myocardial performance index during stress testing.

    PubMed

    Anh Dinh; Bui, Francis M; Tam Nguyen

    2016-08-01

    Stress testing is used to measure the performance of the heart in an elevated stress state, in order to monitor or diagnose certain heart problems. Many measurements can be used to determine the performance of the heart, with the Tei index being the measurement of interest in this work. The Tei index has been used as a reliable method to evaluate systolic and diastolic performance, as it overcomes some limitations of the classical echocardiographic indices. It is calculated based on the time intervals derived from echocardiography. This paper presents an exploratory study, which uses an accelerometer to record mechanical events occurring in each cardiac cycle, also known as the seismocardiogram (SCG). From timing measurements corresponding to various events in the heart, a metric for myocardial performance is calculated based on the Tei index. The use of SCG in addition to ECG has the potential to provide further insights about the heart during stress testing, since the SCG quantifies mechanical actions of the heart.

  14. Prognostic value of tissue Doppler right ventricular systolic and diastolic function indexes combined with plasma B-type natriuretic Peptide in patients with advanced heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

    PubMed

    Bistola, Vasiliki; Parissis, John T; Paraskevaidis, Ioannis; Panou, Fotios; Nikolaou, Maria; Ikonomidis, Ignatios; Flessas, Nikolaos; Filippatos, Gerasimos; Iliodromitis, Efstathios; Kremastinos, Dimitrios T

    2010-01-15

    Right ventricular (RV) dysfunction adversely affects prognosis in patients with chronic heart failure (CHF) due to left ventricular (LV) dysfunction. However, little evidence exists regarding the prognostic role of RV systolic and diastolic function indexes in combination with plasma B-type natriuretic peptide (BNP) in advanced CHF. Thus, 102 consecutive hospitalized patients with advanced CHF (New York Heart Association classes III to IV) due to LV systolic dysfunction (LV ejection fraction <35%) were studied by 2-dimensional conventional and tissue Doppler imaging (TDI) echocardiography of the left and right ventricles. Plasma BNP was also measured. Patients were followed for 6 months for major cardiovascular events (cardiovascular death and/or CHF-related hospitalization). During follow-up, 13 patients died and 63 patients reached the combined end point of cardiovascular death or CHF-related hospitalization. By univariate analysis, RV TDI systolic velocity, dilated cardiomyopathy, digoxin treatment (all p values <0.01), and female gender (p <0.05) were associated with increased cardiovascular death. Transmitral Doppler to mitral annular TDI early diastolic velocity ratio, RV TDI early diastolic velocity (p <0.05), and ratio of early to late RV diastolic TDI velocities (p <0.01) predicted the combined end point. In multivariate analysis, decreased RV systolic velocity, dilated cardiomyopathy, and female gender (all p values <0.05) were independent predictors of cardiovascular death, whereas increased ratio of early to late RV diastolic TDI velocities (p <0.01) and increased BNP (p <0.05) predicted the combined end point. In conclusion, RV TDI indexes combined with increased plasma BNP additively predict adverse cardiac outcomes in advanced CHF.

  15. Doppler assessment of the pulsatility index of the middle cerebral artery during constriction of the fetal ductus arteriosus after indomethacin therapy.

    PubMed

    Mari, G; Moise, K J; Deter, R L; Kirshon, B; Huhta, J C; Carpenter, R J; Cotton, D B

    1989-12-01

    To investigate the effects of constriction of the ductus arteriosus on the pulsatility index of the middle cerebral artery, maximum velocity waveforms were obtained in 13 fetuses (one set of twins) whose mothers were treated with indomethacin for preterm labor (n = 9) or polyhydramnios (n = 3). Eleven of the fetuses manifested ductal constriction within 48 hours of therapy, whereas two fetuses had constriction after 1 week of therapy. Six of the 13 fetuses also manifested tricuspid insufficiency in association with constriction of the ductus arteriosus. All abnormal cardiac changes resolved in utero after discontinuation of indomethacin. No difference in the pulsatility index values of the middle cerebral artery was observed in the fetuses with ductal constriction but without tricuspid regurgitation (n = 7) when the values were compared with those obtained in absence of ductal constriction (1.87 +/- 0.37 vs. 1.88 +/- 0.33). In the fetuses that manifested both ductal constriction and tricuspid insufficiency (n = 6), the pulsatility index values in the middle cerebral artery were significantly lower in the presence of ductal constriction when compared with the values obtained in the absence of ductal constriction (2.22 +/- 0.26 vs. 1.57 +/- 0.34). These results indicate that a response to indomethacin sufficient to cause both ductal constriction and tricuspid insufficiency decreases the pulsatility index of the middle cerebral artery.

  16. Tissue Doppler indexes of left ventricular systolic function in relation to the pulsatile and steady components of blood pressure in a general population.

    PubMed

    Sakiewicz, Wojciech; Kuznetsova, Tatiana; Kloch-Badelek, Malgorzata; D'hooge, Jan; Ryabikov, Andrew; Kunicka, Katarzyna; Swierblewska, Ewa; Thijs, Lutgarde; Jin, Yu; Loster, Magdalena; Malyutina, Sofia; Stolarz-Skrzypek, Katarzyna; Kawecka-Jaszcz, Kalina; Narkiewicz, Krzysztof; Staessen, Jan A

    2012-02-01

    To our knowledge, no population study described the association of the radial and longitudinal components of left ventricular strain with blood pressure (BP) components in continuous analyses. We therefore investigated these associations in participants randomly recruited from the general population in the framework of the family-based European Project on Genes in Hypertension. In 334 participants (55.4% women; mean age, 43.6 year), using tissue Doppler imaging (TDI), we measured the end-systolic longitudinal strain (mean 20.9%) and peak systolic strain rate (1.29 s) from the basal portion of the left ventricular inferior and posterior free walls and radial stain (51.1%) and strain rate (3.40 s) of the left ventricular posterior wall. Models included in addition to covariables and confounders both SBP and DBP or both pulse pressure (PP) and mean arterial pressure (MAP). Effect sizes were expressed per 1-SD increase in BP. Longitudinal strain (-0.62%; P = 0.04 and -0.64%; P = 0.007), but not strain rate, decreased with DBP and MAP. Radial strain (4.0 and -3.4%; P ≤ 0.001) and strain rate (0.38 and -0.18 s; P ≤ 0.04) independently increased with SBP and decreased with DBP. Accordingly, radial strain (2.9%; P < 0.0001) and strain rate (0.22 s; P = 0.0005) increased with higher PP, but were not related to MAP. In the general population, BP is an independent determinant of left ventricular systolic function as measured by TDI. Radial function increased with PP, the pulsatile BP component, whereas longitudinal function decreased with the steady component of BP as expressed by MAP or DBP.

  17. Pre and postoperative evaluation of transcranial Doppler pulsatility index of the middle cerebral artery in patients with severe carotid artery stenosis.

    PubMed

    Bracale, Umberto Marcello; Spalla, Flavia; Caioni, Federica; Solari, Domenico; Narese, Donatella; Pecoraro, Felice; Del Guercio, Luca

    2016-01-01

    Il Doppler transcranico (TCD) viene frequentemente utilizzato per la valutazione delle resistenze periferiche cerebrali e del flusso cerebrale a livello dell’arteria cerebrale media sia prima che durante chirurgia carotidea. Nella gestione della stenosi carotidea severa particolare importanza deve essere data alla valutazione del rischio di eventi ischemici cerebrali intraoperatori. Il nostro studio ha analizzato la possibile relazione tra l’indice di Gosling dell’arteria cerebrale media, calcolato mediante TCD preoperatorio e la Stump Pressure (SP) intra-operatoria, al fine di identificare i pazienti con elevato rischio di eventi ischemici. Inoltre, abbiamo registrato l’indice di Gosling pre e post operatorio correlandolo con possibili eventi durante il follow-up. In un lasso di tempo di un anno 47 pazienti sono stati sottoposti ad endoarterectomia carotidea (CEA) o stenting carotideo (CAS) con sistema di protezione embolica prossimale. Tutti i pazienti sono stati sottoposti a TCD pre e post-operatorio con calcolo dell’Indice Gosling e SP intra-operatoria. Abbiamo osservato che l’aumento di valori pre-operatori dell’Indice di Gosling sono associati a più bassi valori intra-operatori di SP, elementi che rappresentano un rischio più elevato di incidenti ischemici cerebrovascolari; Questo risultato è particolarmente evidente quando si osserva la sotto-popolazione di pazienti diabetici. Non vi e’ stata alcuna differenza statisticamente significativa, per quanto concerne eventi ischemici perioperatori, tra i pazienti sottoposti a CEA o CAS. Il TCD e la SP sono esami validi e semplici che possono aiutare a identificare precocemente i pazienti con un rischio più elevato di incidenti cerebro-vascolari correlati al trattamento chirurgico o endovascolare.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    ERIC Educational Resources Information Center

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

    2008-01-01

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

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

    ERIC Educational Resources Information Center

    Ritzmann, Sandrina; Hagemann, Vera; Kluge, Annette

    2014-01-01

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

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

    ERIC Educational Resources Information Center

    Ritzmann, Sandrina; Hagemann, Vera; Kluge, Annette

    2014-01-01

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

  2. Comparison between doppler ultrasound resistive index, serum creatinine, and histopathologic changes in patients with kidney transplant dysfunction in early posttransplantation period: A single center study with review of literature.

    PubMed

    Patel, Kajal N; Patel, Nitin A; Gandhi, Shruti P

    2016-05-01

    To determine the relationship between resistive index (RI) measured by Doppler ultrasound, serum creatinine (SCr), and histopathological changes on biopsy during kidney trans- plant dysfunction in early postoperative period, we studied 47 kidney transplant patients; 61% of the patients had acute transplant rejection, 19% had acute tubular necrosis, 4% had calcineurin inhibitor toxicity, 11% had normal morphology in biopsy, and 5% had changes compatible with pyelonephritis. None of the study patients had interstitial fibrosis or tubular atrophy on biopsy. We found that the sensitivity and specificity of RI in diagnosing transplant dysfunction was highly variable depending on the selected cutoff value. Sensitivity of RI decreased and its specificity increased with increasing the RI thresholds. Using an RI threshold of 0.7 resulted in a high sensitivity of 78% at a cost of very low specificity 40%, whereas using an RI threshold of 0.9 resulted in 100% specificity at a cost of very low sensitivity 16%. Acceptable specificity was only achieved at the expense of very low sensitivity, resulting in poor utility of RI as a screening tool for dysfunction. We found that there were no significant differences in the mean RI value between patients with and without biopsy-proven transplant dysfunction. However, we found a significant correlation between SCr value and RI of 0.383, P = 0.007.

  3. A pilot study of systolic dyssynchrony index by real time three-dimensional echocardiography and Doppler tissue imaging parameters predicting the hemodynamic response to biventricular pacing in the early postoperative period after cardiac surgery.

    PubMed

    Straka, Frantisek; Pirk, Jan; Pindak, Marian; Marek, Tomas; Schornik, David; Cihak, Robert; Skibova, Jelena

    2012-08-01

    To evaluate systolic dyssynchrony index (SDI) measured by real time three-dimensional echocardiography (RT3DE) and Doppler tissue imaging (DTI) dyssynchrony parameters in predicting the hemodynamic response to biventricular (BIV) pacing in the early postoperative period after cardiac surgery. To compare right ventricular (RV) and BIV pacing using invasively measured hemodynamic values. A prospective randomized clinical study enrolling 11 patients with ischemic heart disease, concomitant valvular heart disease, and left ventricular ejection fraction (LVEF) ≤ 35% comparing preoperative SDI by RT3DE and DTI LV dyssynchrony parameters to hemodynamic values obtained during RV or BIV sequential (DDD) epicardial pacing in the first 72 hours after cardiac surgery. BIV pacing produced a statistically significant higher cardiac output (CO) (6.27 ± 1.55 L/min) and cardiac index (CI) (3.44 ± 0.93 L/min per m(2) ) than RV pacing (CO 5.44 ± 0.97 L/min, CI 3.03 ± 0.83 L/min per m(2) , P < 0.05). We found a statistically moderate correlation between preoperative SDI by RT3DE and CO (r = 0.596, P < 0.05) and a nonsignificant correlation to CI (r = 0.535, P < 0.10) during BIV pacing. No correlation was observed between DTI dyssynchrony parameters and measured hemodynamic values. BIV pacing reduced the ICU stay and inotropic support requirements of patients after heart surgery. SDI measured preoperatively using RT3DE can predict CO during BIV pacing in the early postoperative period after cardiac surgery. BIV pacing is more hemodynamically effective than RV pacing in patients with LV dysfunction after coronary artery bypass grafting with or without a valve procedure. © 2012, Wiley Periodicals, Inc.

  4. Christian Doppler and the Doppler effect

    NASA Astrophysics Data System (ADS)

    Toman, Kurt

    1984-04-01

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

  5. Doppler ultrasound evaluation in preeclampsia

    PubMed Central

    2013-01-01

    Background Worldwide preeclampsia (PE) is the leading cause of maternal death and affects 5 to 8% of pregnant women. PE is characterized by elevated blood pressure and proteinuria. Doppler Ultrasound (US) evaluation has been considered a useful method for prediction of PE; however, there is no complete data about the most frequently altered US parameters in the pathology. The aim of this study was to evaluate the uterine, umbilical, and the middle cerebral arteries using Doppler US parameters [resistance index (RI), pulsatility index (PI), notch (N), systolic peak (SP) and their combinations] in pregnant women, in order to make a global evaluation of hemodynamic repercussion caused by the established PE. Results A total of 102 pregnant Mexican women (65 PE women and 37 normotensive women) were recruited in a cases and controls study. Blood velocity waveforms from uterine, umbilical, and middle cerebral arteries, in pregnancies from 24 to 37 weeks of gestation were recorded by trans-abdominal examination with a Toshiba Ultrasound Power Vision 6000 SSA-370A, with a 3.5 MHz convex transducer. Abnormal general Doppler US profile showed a positive association with PE [odds ratio (OR) = 2.93, 95% confidence interval (CI) = 1.2 - 7.3, P = 0.021)], and a specificity and predictive positive value of 89.2% and 88.6%, respectively. Other parameters like N presence, RI and PI of umbilical artery, as well as the PI of middle cerebral artery, showed differences between groups (P values < 0.05). Conclusion General Doppler US result, as well as N from uterine vessel, RI from umbilical artery, and PI from umbilical and middle cerebral arteries in their individual form, may be considered as tools to determine hemodynamic repercussion caused by PE. PMID:24252303

  6. Doppler ultrasound evaluation in preeclampsia.

    PubMed

    Lopez-Mendez, Maria A; Martinez-Gaytan, Victoria; Cortes-Flores, Raul; Ramos-Gonzalez, Rene M; Ochoa-Torres, Mauro A; Garza-Veloz, Idalia; Martinez-Acuña, Monica I; Badillo-Almaraz, Jose I; Martinez-Fierro, Margarita L

    2013-11-19

    Worldwide preeclampsia (PE) is the leading cause of maternal death and affects 5 to 8% of pregnant women. PE is characterized by elevated blood pressure and proteinuria. Doppler Ultrasound (US) evaluation has been considered a useful method for prediction of PE; however, there is no complete data about the most frequently altered US parameters in the pathology. The aim of this study was to evaluate the uterine, umbilical, and the middle cerebral arteries using Doppler US parameters [resistance index (RI), pulsatility index (PI), notch (N), systolic peak (SP) and their combinations] in pregnant women, in order to make a global evaluation of hemodynamic repercussion caused by the established PE. A total of 102 pregnant Mexican women (65 PE women and 37 normotensive women) were recruited in a cases and controls study. Blood velocity waveforms from uterine, umbilical, and middle cerebral arteries, in pregnancies from 24 to 37 weeks of gestation were recorded by trans-abdominal examination with a Toshiba Ultrasound Power Vision 6000 SSA-370A, with a 3.5 MHz convex transducer. Abnormal general Doppler US profile showed a positive association with PE [odds ratio (OR) = 2.93, 95% confidence interval (CI) = 1.2 - 7.3, P = 0.021)], and a specificity and predictive positive value of 89.2% and 88.6%, respectively. Other parameters like N presence, RI and PI of umbilical artery, as well as the PI of middle cerebral artery, showed differences between groups (P values < 0.05). General Doppler US result, as well as N from uterine vessel, RI from umbilical artery, and PI from umbilical and middle cerebral arteries in their individual form, may be considered as tools to determine hemodynamic repercussion caused by PE.

  7. Cilostazol decreases cerebral arterial pulsatility in patients with mild white matter hyperintensities: subgroup analysis from the Effect of Cilostazol in Acute Lacunar Infarction Based on Pulsatility Index of Transcranial Doppler (ECLIPse) study.

    PubMed

    Han, Sang Won; Song, Tae Jin; Bushnell, Cheryl D; Lee, Sung-Soo; Kim, Seo Hyun; Lee, Jun Hong; Kim, Gyu Sik; Kim, Ok-Joon; Koh, Im-Seok; Lee, Jong Yun; Suk, Seung-Han; Lee, Sung Ik; Nam, Hyo Suk; Kim, Won-Joo; Lee, Kyung-Yul; Park, Joong Hyun; Kim, Jeong Yeon; Park, Jae Hyeon

    2014-01-01

    The Effect of Cilostazol in Acute Lacunar Infarction Based on Pulsatility Index of the Transcranial Doppler (ECLIPse) study showed a significant decrease in the transcranial Doppler (TCD) pulsatility index (PI) with cilostazol treatment at 90 days after acute lacunar infarction. The aim of the present study was to perform a subgroup analysis of the ECLIPse study in order to explore the effect of cilostazol in acute lacunar infarction based on cerebral white matter hyperintensities (WMH) volume. The ECLIPse study was a multicenter, randomized, double-blind, placebo-controlled trial that evaluated the difference between the efficacy of cilostazol and a placebo to reduce the PI in patients with acute lacunar infarction using serial TCD examinations. The primary outcome was changes in the PIs of the middle cerebral artery (MCA) and basilar artery at 14 and 90 days from the baseline TCD study. For this subgroup analysis, using semi-automated computerized software, the WMH volume was measured for those subjects for whom fluid-attenuated inversion recovery (FLAIR) images were available. Of the 203 patients in eight hospitals in the ECLIPse study, 130 participants from six hospitals were included in this subgroup analysis. Cilostazol was given to 63 patients (48.5%) and placebo to 67 patients (51.5%). All baseline characteristics were well balanced across the two groups, and there were no significant differences in these characteristics except in the changes of PI from the baseline to the 90-day point. There was a significant decrease of TCD PIs at 90-day study from baseline in the cilostazol group (p = 0.02). The mean WMH volume was 11.57 cm(3) (0.13-68.45, median 4.86) and the mean MCA PI was 0.95 (0.62-1.50). The changes in PIs from the baseline to 14 days and to 90 days were 0.09 (-0.21 to 0.33) and 0.10 (-0.22 to 0.36). While there were no significant correlations between WMH volume and the changes in PIs, a trend of inverse correlation was observed between the WMH

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  9. Reference values for placental growth factor (PlGF) concentration and uterine artery doppler pulsatility index (PI) at 11-13(+6) weeks of gestation in the Polish population.

    PubMed

    Kosiński, Przemysław; Samaha, Robert Brawura Biskupski; Bomba-Opoń, Dorota A; Kozłowski, Szymon; Lipa, Michał; Kaczyński, Bartosz; Zbucka-Kretowska, Monika; Lawicki, Sławomir; Szmitkowski, Maciej; Wolczyński, Sławomir; Wielgoś, Mirosław

    2014-07-01

    The aim of the study was to determine placental growth factor (PIGF) concentration and uterine artery (UtA) Doppler pulsatility index (PI) at 11-13(+6) weeks of gestation in the Polish population. A prospective study was performed in pregnant women who underwent routine ultrasound scan at 11-13(+6) weeks of gestation. All participants completed a questionnaire about their medical history demographics and current pregnancy. Mean arterial pressure (MAP) was calculated. Gestational age was confirmed by CRL and mean UtA PI was calculated. Blood samples were taken to measure beta HCG, PAPP-A and P/GF concentrations. Out of the 577 analyzed participants, 60 (10.4%) were found to have abnormal placentation disorders (20 -hypertensive disorders and 40-IUGR). The patients were subdivided into two groups, depending on pregnancy outcome: unaffected (n = 517) and affected (n = 60). The study did not confirm the anticipated correlation between maternal BMI and PIGF, but the concentration of PIGF was significantly increased in smokers. UtA PI values were not statistically significantly different depending on maternal age, BMI, method of conception, smoking or parity The study confirms that both, UtA PI and PIGF concentrations are CRL-dependent. Median MoM values for PIGF and UtA PI were obtained for each set of CRL measurements. Median PIGF MoM was decreased in pregnancies complicated by hypertensive disorders and IUGR as compared to the unaffected group. The established reference ranges for UtA PI and PIGF at 11-13(+6) weeks of gestation may be of clinical value in predicting placenta-associated diseases in early stages of pregnancy in the Polish population.

  10. Doppler flowmetry in preeclampsia.

    PubMed

    Zahumensky, J

    2009-01-01

    The purpose of this study was to summarize the new published data on the Doppler flowmetry in preeclampsia. We summarize the new published data on the Doppler flowmetry in uteroplacental, fetoplacental and fetal circulation in preeclampsia. The present review summarized the results of clinical research on the Doppler flowmetry in the screening of risk of preclampsia, in the diagnosis of preclampsia and in the fetal risk in preclampsia (Ref. 19). Full Text (Free, PDF) www.bmj.sk.

  11. Advances in Doppler OCT

    PubMed Central

    Liu, Gangjun; Chen, Zhongping

    2014-01-01

    We review the principle and some recent applications of Doppler optical coherence tomography (OCT). The advances of the phase-resolved Doppler OCT method are described. Functional OCT algorithms which are based on an extension of the phase-resolved scheme are also introduced. Recent applications of Doppler OCT for quantification of flow, imaging of microvasculature and vocal fold vibration, and optical coherence elastography are briefly discussed. PMID:24443649

  12. Advanced Doppler tracking experiments

    NASA Technical Reports Server (NTRS)

    Armstrong, J. W.

    1989-01-01

    The Doppler tracking method is currently the only technique available for broadband gravitational wave searches in the approx. 10(exp -4) to 10(exp -1) Hz low frequency band. A brief review is given of the Doppler method, a discussion of the main noise sources, and a review of experience with current spacecraft and the prospects for sensitivity improvements in an advanced Doppler tracking experiment.

  13. The E-wave deceleration rate E/DT outperforms the tissue Doppler-derived index E/e' in characterizing lung remodeling in heart failure with preserved ejection fraction.

    PubMed

    Nguyen, T Dung; Shingu, Yasushige; Schwarzer, Michael; Schrepper, Andrea; Doenst, Torsten

    2013-01-01

    Diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF) may result in pulmonary congestion and lung remodeling. We evaluated the usefulness of major diastolic echocardiographic parameters and of the deceleration rate of early transmitral diastolic velocity (E/DT) in predicting lung remodeling in a rat model of HFpEF. Rats underwent aortic banding (AoB) to induce pressure overload (PO). Left ventricular hypertrophy fully developed 2 weeks after AoB. At 4 and 6 weeks, the lung weight-to-body weight ratio (LW/BW), a sensitive marker for pulmonary congestion and remodeling, dramatically increased despite preserved fractional shortening, indicating the presence of HFpEF. The time course of LW/BW was well reflected by E/DT, by the ratio of early to late transmitral diastolic velocity (E/A) and the deceleration time of E (DT), but not by the ratio of transmitral to mitral annular early diastolic velocity (E/e'). In agreement, the best correlation with LW/BW was found for E/DT (r = 0.76; p<0.0001), followed by E/A (r = 0.69; p<0.0001), DT (r = -0.62; p<0.0001) and finally E/e' (r = 0.51; p<0.001). Furthermore, analysis of receiver-operating characteristic curves for the prediction of increased LW/BW revealed excellent area under the curve values for E/DT (AUC = 0.98) and DT (AUC = 0.95), which are significantly higher than that of E/e' (AUC = 0.82). In a second approach, we also found that the new parameter E/DT correlated well with right ventricular weight index and echocardiographic measures of right ventricular systolic function. The novel parameter E/DT outperforms the tissue Doppler index E/e' in detecting and monitoring lung remodeling induced by pressure overload. The results may provide a handy tool to point towards secondary lung disease in HFpEF and warrant further clinical investigations.

  14. The Cognitive Doppler.

    ERIC Educational Resources Information Center

    Kozoil, Micah E.

    1989-01-01

    Discusses the learning needs of students in the concrete operational stage in mathematics. Identifies the phenomenon of reduced cognitive performance in an out-of-class environment as the "Cognitive Doppler." Suggests methods of reducing the pronounced effects of the Cognitive Doppler by capitalizing on the students' ability to memorize…

  15. Doppler ultrasound monitoring technology.

    PubMed

    Docker, M F

    1993-03-01

    Developments in the signal processing of Doppler ultrasound used for the detection of fetal heart rate (FHR) have improved the operation of cardiotocographs. These developments are reviewed and the advantages and disadvantages of the various Doppler and signal processing methods are compared.

  16. The Cognitive Doppler.

    ERIC Educational Resources Information Center

    Kozoil, Micah E.

    1989-01-01

    Discusses the learning needs of students in the concrete operational stage in mathematics. Identifies the phenomenon of reduced cognitive performance in an out-of-class environment as the "Cognitive Doppler." Suggests methods of reducing the pronounced effects of the Cognitive Doppler by capitalizing on the students' ability to memorize…

  17. Joint Agency Doppler Technology Tests.

    DTIC Science & Technology

    DOPPLER RADAR, *METEOROLOGICAL RADAR, *EARLY WARNING SYSTEMS, DAMAGE, HAZARDS, NETWORKS, REAL TIME, RADAR, IDENTIFICATION, RELIABILITY, HAIL, AIR FORCE FACILITIES, DOPPLER SYSTEMS, AIRPORTS, WARNING SYSTEMS, TORNADOES .

  18. Doppler radar flowmeter

    DOEpatents

    Petlevich, Walter J.; Sverdrup, Edward F.

    1978-01-01

    A Doppler radar flowmeter comprises a transceiver which produces an audio frequency output related to the Doppler shift in frequency between radio waves backscattered from particulate matter carried in a fluid and the radiated radio waves. A variable gain amplifier and low pass filter are provided for amplifying and filtering the transceiver output. A frequency counter having a variable triggering level is also provided to determine the magnitude of the Doppler shift. A calibration method is disclosed wherein the amplifier gain and frequency counter trigger level are adjusted to achieve plateaus in the output of the frequency counter and thereby allow calibration without the necessity of being able to visually observe the flow.

  19. [Relationship between the ankle-arm index determined by Doppler ultrasonography and cardiovascular outcomes and amputations, in a group of patients with type 2 diabetes mellitus from the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán].

    PubMed

    Miranda Garduño, Luis Miguel; Bermúdez Rocha, Rocío; Gómez Pérez, Francisco J; Aguilar Salinas, Carlos A

    2011-01-01

    An ankle/arm index < 0.90 and ≥ 1.41 is considered as abnormal. This study was aimed to investigate the prevalence of peripheral arterial disease through the identification of the ankle/arm index using Doppler ultrasound, and the possible association between pathological ankle/arm index and the micro- and macrovascular complications of diabetes and amputation. The ankle/arm index was determined in outpatient type 2 diabetic subjects. There were the following variables: age and cardiovascular outcomes. To find if the ankle/arm index is related to the cardiovascular outcomes or with the presence of micro- or macrovascular complications we determined the index of correlation of Pearson and also used logistic regression methods to analyze the association between ankle/arm index with the categorical variables. We calculated the ankle/arm index in 242 patients. The prevalence of ischemic ankle/arm index (< 0.90) was 13.6%. The Pearson correlation coefficient for ankle/arm index pathological and cardiovascular outcomes was 0.180 (p = 0.005), amputation 0.130 (p < 0.05), retinopathy 0.132 (p < 0.05), and nephropathy 0.158 (p = 0.01). In logistic regression analysis, the factors associated with pathological ankle/arm index were age > 51 years, cardiovascular outcomes, and amputation. With the Mann Whitney U test we found that a relationship exists between pathological and amputation iliotibial band (p < 0.05). Diabetic patients have a high prevalence of pathological ankle/arm index.

  20. Doppler Lidar (DL) Handbook

    SciTech Connect

    Newsom, RK

    2012-02-13

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

  1. Pulse subtraction Doppler

    NASA Astrophysics Data System (ADS)

    Mahue, Veronique; Mari, Jean Martial; Eckersley, Robert J.; Caro, Colin G.; Tang, Meng-Xing

    2010-01-01

    Recent advances have demonstrated the feasibility of molecular imaging using targeted microbubbles and ultrasound. One technical challenge is to selectively detect attached bubbles from those freely flowing bubbles and surrounding tissue. Pulse Inversion Doppler is an imaging technique enabling the selective detection of both static and moving ultrasound contrast agents: linear scatterers generate a single band Doppler spectrum, while non-linear scatterers generate a double band spectrum, one being uniquely correlated with the presence of contrast agents and non-linear tissue signals. We demonstrate that similar spectrums, and thus the same discrimination, can be obtained through a Doppler implementation of Pulse Subtraction. This is achieved by reconstructing a virtual echo using the echo generated from a short pulse transmission. Moreover by subtracting from this virtual echo the one generated from a longer pulse transmission, it is possible to fully suppress the echo from linear scatterers, while for non-linear scatterers, a signal will remain, allowing classical agent detection. Simulations of a single moving microbubble and a moving linear scatterer subject to these pulses show that when the virtual echo and the long pulse echo are used to perform pulsed Doppler, the power Doppler spectrum allows separation of linear and non-linear moving scattering. Similar results are obtained on experimental data acquired on a flow containing either microbubble contrast agents or linear blood mimicking fluid. This new Doppler method constitutes an alternative to Pulse Inversion Doppler and preliminary results suggest that similar dual band spectrums could be obtained by the combination of any non-linear detection technique with Doppler demodulation.

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

    PubMed Central

    2015-01-01

    Purpose: The purpose of this study was to investigate the value of UltraFast Doppler ultrasonography (US) for evaluating hepatic vessels in liver recipients. Methods: Thirty-nine liver Doppler US sessions were conducted in 20 liver recipients. Each session consisted of UltraFast and conventional liver Doppler US in a random order. We compared the velocities and phasicities of the hepatic vessels, duration of each Doppler study, occurrence of technical failures, and differences in clinical decisions. Results: The velocities and resistive index values of hepatic vessels showed a strong positive correlation between the two Doppler studies (mean R=0.806; range, 0.710 to 0.924). The phasicities of the hepatic vessels were the same in both Doppler US exams. With respect to the duration of the Doppler US exam, there was no significant difference between the UltraFast (251±99 seconds) and conventional (231±117 seconds) Doppler studies (P=0.306). In five poor breath-holders, in whom the duration of conventional Doppler US was longer, UltraFast Doppler US (272±157 seconds) required a shorter time than conventional Doppler US (381±133 seconds; P=0.005). There was no difference between the two techniques with respect to technical failures and clinical decisions. Conclusion: UltraFast Doppler US is clinically equivalent to conventional Doppler US with advantages for poor breath-holders during the post-liver transplantation work-up. PMID:25409662

  3. Assessment of left ventricular function with tissue Doppler echocardiography and of B-type natriuretic peptide levels in patients undergoing transcatheter aortic valve implantation.

    PubMed

    Yüksel, Isa Oner; Arslan, Sakir; Cagirci, Goksel; Koklu, Erkan; Ureyen, Cagin M; Bayar, Nermin; Kucukseymen, Selcuk; Kus, Gorkem; Guven, Ramazan

    2017-05-01

    Transcatheter aortic valve implantation (TAVI) is an emerging minimally invasive treatment modality in high surgical risk or inoperable patients. The aim of this study was to ascertain the effect of TAVI on left ventricular (LV) systolic and diastolic function and serum B-type natriuretic peptide (BNP) levels in high surgical risk or inoperable patients with severe aortic stenosis. Fifty-five patients were included in our retrospective study. LV systolic and diastolic function was assessed with conventional and tissue Doppler imaging (TDI) prior to and after TAVI. Additionally, BNP was measured 24 h before and three months after the procedure. Echocardiographic controls were performed at one, three and six months and one year and mean values were taken. At the end of the study, LV systolic and diastolic function, serum BNP levels and New York Heart Association functional capacity were assessed and compared to baseline parameters. The TAVI procedure was successful in all patients. In-hospital mortality was 1.8% (one patient). There was a substantial improvement in LV function and functional capacity at follow-up. In addition, a statistically significant decrease was detected in serum BNP levels post-TAVI (median 380 pg/ml [176.6-929.3] vs. 215 pg/ml [96.0-383.0], p=0.0001). Only one patient required a permanent pacemaker (1.8%) and there was no mortality after TAVI during follow-up. There were significant increases in LV ejection fraction and aortic valve area (51.0±13.1% vs. 58.4±9.1%, p<0.001, and 0.6±0.1 cm(2) vs. 2.1±0.2 cm(2), p=0.0001, respectively). At the end of the study, conventional Doppler echocardiography revealed improvement in diastolic function, with an increase in mitral E wave, a decrease in mitral A wave and an increase in E/A ratio. Deceleration time and isovolumetric relaxation time were shortened and myocardial performance (Tei) index decreased. TDI showed an increase in systolic myocardial velocity (Sm) and early diastolic velocity (Em

  4. Penile Doppler ultrasonography revisited.

    PubMed

    Jung, Dae Chul; Park, Sung Yoon; Lee, Joo Yong

    2017-06-10

    Penile Doppler ultrasonography is a high-performing, noninvasive or minimally-invasive imaging modality that allows the depiction of the normal anatomy and macroscopic pathologic changes in real time. Moreover, functional changes in penile blood flow, as seen in erectile dysfunction (ED), can be analyzed using color Doppler ultrasonography (CDUS). This review article describes the normal sonographic anatomy of the penis, the sonographic technique for evaluating ED, the normal phases of erection, and the various causes of ED. Additionally, we describe the interpretation of different parameters and findings on penile CDUS for the diagnosis and classification of ED, priapism, and Peyronie disease.

  5. Doppler ion program description

    SciTech Connect

    Henline, P.

    1980-12-01

    The Doppler spectrometer is a conventional Czerny-Turner grating spectrometer with a 1024 channel multiple detector. Light is dispersed across the detector, and its output yields a spectrum covering approximately 200 A. The width of the spectral peak is directly proportional to the temperature of the emitting ions, and determination of the impurity ion temperature allows one to infer the plasma ion temperature. The Doppler ion software system developed at General Atomic uses a TRACOR Northern 1710-31 and an LSI-11/2. The exact configuration of Doublet III is different from TRACOR Northern systems at other facilities.

  6. The Doppler Pendulum Experiment

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  7. The Doppler Pendulum Experiment

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  8. Photonic doppler velocimetry

    SciTech Connect

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

    1999-01-01

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

  9. Finnish Meteorological Institute Doppler Lidar

    SciTech Connect

    Ewan OConnor

    2015-03-27

    This doppler lidar system provides co-polar and cross polar attenuated backscatter coefficients,signal strength, and doppler velocities in the cloud and in the boundary level, including uncertainties for all parameters. Using the doppler beam swinging DBS technique, and Vertical Azimuthal Display (VAD) this system also provides vertical profiles of horizontal winds.

  10. Adaptive Spectral Envelope Estimation for Doppler Ultrasound.

    PubMed

    Kathpalia, Aditi; Karabiyik, Yucel; Eik-Nes, Sturla; Tegnander, Eva; Ekroll, Ingvild; Kiss, Gabriel; Torp, Hans

    2016-07-07

    Estimation of accurate maximum velocities and spectral envelope in ultrasound Doppler blood flow spectrograms are both essential for clinical diagnostic purposes. However, obtaining accurate maximum velocity is not straightforward due to intrinsic spectral broadening and variance in the power spectrum estimate. The method proposed in this work for maximum velocity point detection has been developed by modifying an existing method - Signal Noise Slope Intersection (SNSI), incorporating in it steps from an altered version of another method called Geometric Method (GM). Adaptive noise estimation from the spectrogram ensures that a smooth spectral envelope is obtained post detection of these maximum velocity points. The method has been tested on simulated Doppler signal with scatterers possessing a parabolic flow velocity profile constant in time, steady and pulsatile string phantom recordings as well as in vivo recordings from uterine, umbilical, carotid and subclavian arteries. Results from simulation experiments indicate a bias of less than 2.5% in maximum velocities when estimated for a range of peak velocities, Doppler angles and SNR levels. Standard deviation in the envelope is low - less than 2% in case of experiments done by varying the peak velocity and Doppler angle for steady phantom and simulated flow; and also less than 2% in case of experiments done by varying SNR but keeping constant flow conditions for in vivo and simulated flow. Low variability in the envelope makes the prospect of using the envelope for automated blood flow measurements possible and is illustrated for the case of Pulsatility Index estimation in uterine and umbilical arteries.

  11. Ultrasonic colour Doppler imaging

    PubMed Central

    Evans, David H.; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been found to be of great value in assessing blood flow in many clinical conditions. Although the method for obtaining the velocity information is in many ways similar to the method for obtaining the anatomical information, it is technically more demanding for a number of reasons. It also has a number of weaknesses, perhaps the greatest being that in conventional systems, the velocities measured and thus displayed are the components of the flow velocity directly towards or away from the transducer, while ideally the method would give information about the magnitude and direction of the three-dimensional flow vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new techniques that seek to overcome the vector problem mentioned above are described. Finally, some examples of vector velocity images are presented. PMID:22866227

  12. Testing radon mitigation techniques in a pilot house from Băiţa-Ştei radon prone area (Romania).

    PubMed

    Cosma, Constantin; Papp, Botond; Cucoş Dinu, Alexandra; Sainz, Carlos

    2015-02-01

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

  13. Doppler effect in optical velocimetry

    NASA Astrophysics Data System (ADS)

    Rinkevichius, Bronius S.

    1996-02-01

    The current state of the optical metrology based on the Doppler effect has been reviewed. Some historical and scientific information is given, in addition the contemporary optical methods of the velocity measurement using the Doppler effect are analyzed. The Doppler effect applications in astrophysics, plasma physics, investigations of gas and liquid flows, acoustics, mechanics of the deforming solid body and of the rotational motion are considered. The description is presented for the following techniques of the velocity measurement: laser Doppler anemometry, laser Doppler vibrometry, laser gyroscopy.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  15. An airborne Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Dimarzio, C. A.

    1980-01-01

    A pulsed CO2 Doppler Lidar, developed for airborne measurements of atmospheric wind fields, is described. In-flight tests show that the device can be successfully utilized in the detection and measurement of mountain-wave turbulence and wind shear, and in the generation of time histories of wind-field variations in smooth flight. This Lidar is in the process of being configured for measurement of the atmospheric flow fields surrounding severe convective storms.

  16. Laser Doppler anemometry

    NASA Technical Reports Server (NTRS)

    Johnson, Dennis A.

    1988-01-01

    The material in this NASA TM is to appear as a chapter on Laser Doppler Anemometry (LDA) in the AGARDograph entitled, A Survey of Measurements and Measuring Techniques in Rapidly Distorted Compressible Turbulent Boundary Layers. The application of LDA (specifically, the dual-beam, burst-counter approach) to compressible flows is discussed. Subjects treated include signal processing, particle light scattering and tracking, data reduction and sampling bias, and three-dimensional measurements.

  17. Laser double Doppler flowmeter

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  18. Doppler Optical Coherence Tomography

    PubMed Central

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

    2014-01-01

    Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A common problem with the technique is that the Doppler angle is not known and several approaches have been realized to obtain absolute velocity and flow data from the retina. Additional studies are required to elucidate which of these techniques is most promising. In the recent years, however, several groups have shown that data can be obtained with high validity and reproducibility. In addition, several groups have published values for total retinal blood flow. Another promising application relates to non-invasive angiography. As compared to standard techniques such as fluorescein and indocyanine-green angiography the technique offers two major advantages: no dye is required and depth resolution is required is provided. As such Doppler OCT has the potential to improve our abilities to diagnose and monitor ocular vascular diseases. PMID:24704352

  19. [Color-Doppler semiology in transplanted kidney].

    PubMed

    Rivolta, R; Castagnone, D; Burdick, L; Mandelli, C; Mangiarotti, R

    1993-05-01

    Color-encoded duplex ultrasonography (CEDU) makes a more accurate technique in kidney graft monitoring by combining real-time US with pulsed Doppler studies of renal vasculature. It is a non-invasive and easy technique. Suitable to study the whole renal artery and vein, CEDU also allows the qualitative and quantitative assessment of the intrarenal vasculature and therefore the easy diagnosis of such vessel dysfunctions as arteriovenous fistulas following biopsy. Moreover, Doppler spectral analysis can be used to distinguish among different causes of renal allograft dysfunction--i.e. rejection, cyclosporine nephrotoxicity or acute tubular necrosis. The value of the resistive index for the differential diagnosis is discussed. CEDU allows a more reliable measurement of renal blood flow thanks to the more precise evaluation of renal artery diameter and mean flow velocity.

  20. Clinical applications of doppler ultrasound

    SciTech Connect

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

    1987-01-01

    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.

  1. Growth and characterization of large weak topological insulator Bi2TeI single crystal by Bismuth self-flux method

    NASA Astrophysics Data System (ADS)

    Ryu, Gihun; Son, Kwanghyo; Schütz, Gisela

    2016-04-01

    Two dimensional (2D) topological insulators (TIs) with a quantum spin Hall (QSH) effect feature edge states (ESs) that are topologically protected from backscattering. Bi2TeI with 2D Bismuth bilayer is one of the representative compounds of weak topological insulator. However, nobody has prepared a high quality single crystal with a millimeter size so far. Here, we have successfully synthesized a large single crystal sized up to "millimeter (~5×5 mm2)" using the Bismuth self-flux method. And we also found its giant anisotropy transport behavior in Bi2TeI of a 2D TI constructed from nontrivial Bi bilayers (Quantum Spin Hall phase) capped by a trivial Te-Bi-I layer.

  2. Developing a measure of engagement with telehealth systems: The mHealth Technology Engagement Index.

    PubMed

    Dewar, Alexis R; Bull, Tyler P; Malvey, Donna M; Szalma, James L

    2017-02-01

    Introduction Telehealth systems and mobile health (mHealth) devices allow for the exchange of both physical and mental healthcare data, as well as information from a patient to a practitioner, or care recipient to caregiver; but there has been little research on why users are motivated to engage with telehealth systems. Given this, we sought to create a measure that satisfactorily assesses human motivation to use telehealth devices. Methods 532 survey responses were used in an exploratory factor analysis and confirmatory factor analysis, which tested and retested the feasibility of this new measure. Convergent and divergent validity analyses indicated that the mHealth Technology Engagement Index (mTEI) is a unique measure of motivation. Results The results indicated that autonomy, competence, relatedness, goal attainment, and goal setting underpin motivation to use telehealth systems. Discussion The mTEI shows promise in indexing human motivation to use telehealth technologies. We also discuss the importance of developing measurement tools based on theory and how practitioners can best utilize the mTEI.

  3. Laser Doppler diagnostics for orthodontia

    NASA Astrophysics Data System (ADS)

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

    2004-06-01

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

  4. Neutrino Induced Doppler Broadening

    PubMed Central

    Jolie, J.; Stritt, N.

    2000-01-01

    When a nucleus undergoes beta decay via the electron capture reaction, it emits an electron neutrino. The neutrino emission gives a small recoil to the atom, which can be experimentally observed as a Doppler broadening on subsequently emitted gamma rays. Using the two-axis flat-crystal spectrometer GAMS4 and the electron capture reaction in 152Eu, the motion of atoms having an excess kinetic energy of 3 eV in the solid state was studied. It is shown how the motion of the atom during the first hundreds of femtoseconds can be reconstructed. The relevance of this knowledge for a new neutrino helicity experiment is discussed. PMID:27551591

  5. Laser Doppler velocimetry primer

    NASA Technical Reports Server (NTRS)

    Bachalo, William D.

    1985-01-01

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

  6. ANL Doppler flowmeter

    NASA Astrophysics Data System (ADS)

    Karplus, H. B.; Raptis, A. C.; Lee, S.; Simpson, T.

    1985-10-01

    A flowmeter has been developed for measuring flow velocity in hot slurries. The flowmeter works on an ultrasonic Doppler principle in which ultrasound is injected into the flowing fluid through the solid pipe wall. Isolating waveguides separate the hot pipe from conventional ultrasonic transducers. Special clamp-on high-temperature transducers also can be adapted to work well in this application. Typical flows in pilot plants were found to be laminar, giving rise to broad-band Doppler spectra. A special circuit based on a servomechanism sensor was devised to determine the frequency average of such a broad spectrum. The device was tested at different pilot plants. Slurries with particulates greater than 70 microns (0.003 in.) yielded good signals, but slurries with extremely fine particulates were unpredictable. Small bubbles can replace the coarse particles to provide a good signal if there are not too many. Successful operation with very fine particulate slurries may have been enhanced by the presence of microbubbles.

  7. Doppler ultrasound study of penis in men with systemic sclerosis: a correlation with Doppler indices of renal and digital arteries.

    PubMed

    Rosato, E; Barbano, B; Gigante, A; Cianci, R; Molinaro, I; Quarta, S; Digiulio, M A; Messineo, D; Pisarri, S; Salsano, F

    2013-01-01

    Erectile dysfunction (ED) prevalence in male systemic sclerosis (SSc) is high and its pathogenesis is unclear. The aim of the study is to assess correlation between Doppler ultrasound indices of penis and kidneys or digital arteries in male systemic sclerosis. Fourteen men with systemic sclerosis were enrolled in this study. Erectile function was investigated by the International Index of Erectile Function-5. Peak systolic velocity, end diastolic velocity, resistive index, pulsative index, and systolic/diastolic ratio were measured on the cavernous arteries at the peno-scrotal junction in the flaccid state, on the interlobar artery of both kidneys and all ten proper palmar digital arteries. Ten (71 percent) patients have an International Index of Erectile Function-5 less than 21. Reduction of penis peak systolic velocity was observed in all SSc subjects. Doppler indices of cavernous arteries correlate with the International Index of Erectile Function-5. The renal and digital arteries resistive index demonstrated a good correlation (p less than 0.0001) with International Index of Erectile Function-5. A positive correlation exists between penis and kidney arteries Doppler indices: end diastolic velocity (p less than 0.05, r=0.54), resistive index (p less than 0.0001, r=0.90), systolic/diastolic ratio (p less than 0.01, r=0.69). A positive correlation was observed between penis and digital arteries Doppler indices: peak systolic velocity (p less than 0.01, r=0.68), end diastolic velocity (p less than 0.01, r=0.75), resistive index (p less than 0.001, r=0.79), systolic/diastolic ratio (p less than 0.05, r=0.59). A correlation exists between arterial impairment of penis and renal or digital arteries.

  8. Doppler Beats or Interference Fringes?

    ERIC Educational Resources Information Center

    Kelly, Paul S.

    1979-01-01

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

  9. Doppler Beats or Interference Fringes?

    ERIC Educational Resources Information Center

    Kelly, Paul S.

    1979-01-01

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

  10. Adaptive Spectral Envelope Estimation for Doppler Ultrasound.

    PubMed

    Kathpalia, Aditi; Karabiyik, Yucel; Eik-Nes, Sturla H; Tegnander, Eva; Ekroll, Ingvild Kinn; Kiss, Gabriel; Torp, Hans

    2016-11-01

    Estimation of accurate maximum velocities and spectral envelope in ultrasound Doppler blood flow spectrograms are both essential for clinical diagnostic purposes. However, obtaining accurate maximum velocity is not straightforward due to intrinsic spectral broadening and variance in the power spectrum estimate. The method proposed in this paper for maximum velocity point detection has been developed by modifying an existing method-signal noise slope intersection, incorporating in it steps from an altered version of another method called geometric method. Adaptive noise estimation from the spectrogram ensures that a smooth spectral envelope is obtained postdetection of these maximum velocity points. The method has been tested on simulated Doppler signal with scatterers possessing a parabolic flow velocity profile constant in time, steady and pulsatile string phantom recordings, as well as in vivo recordings from uterine, umbilical, carotid, and subclavian arteries. The results from simulation experiments indicate a bias of less than 2.5% in maximum velocities when estimated for a range of peak velocities, Doppler angles, and SNR levels. Standard deviation in the envelope is low-less than 2% in the case of experiments done by varying the peak velocity and Doppler angle for steady phantom and simulated flow, and also less than 2% in the case of experiments done by varying SNR but keeping constant flow conditions for in vivo and simulated flow. Low variability in the envelope makes the prospect of using the envelope for automated blood flow measurements possible and is illustrated for the case of pulsatility index estimation in uterine and umbilical arteries.

  11. Doppler echocardiographic parameters of evaluation of left ventricular systolic function.

    PubMed

    Drăgulescu, S I; Roşu, D; Abazid, J; Ionac, A

    1993-01-01

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

  12. Doppler echocardiography in athletes from different sports

    PubMed Central

    Moro, Andre Santos; Okoshi, Marina Politi; Padovani, Carlos Roberto; Okoshi, Katashi

    2013-01-01

    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/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. PMID:23478754

  13. Digital Doppler measurement with spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.; Hinedi, Sami M.; Labelle, Remi C.; Bevan, Roland P.; Del Castillo, Hector M.; Chong, Dwayne C.

    1991-01-01

    Digital and analog phase-locked loop (PLL) receivers were operated in parallel, each tracking the residual carrier from a spacecraft. The PLL tracked the downlink carrier and measured its instantaneous phase. This information, combined with a knowledge of the uplink carrier and the transponder ratio, permitted the computation of a Doppler observable. In this way, two separate Doppler measurements were obtained for one observation window. The two receivers agreed on the magnitude of the Doppler effect to within 1 mHz. There was less jitter on the data from the digital receiver. This was due to its smaller noise bandwidth. The demonstration and its results are described.

  14. GEOS-3 Doppler difference tracking

    NASA Technical Reports Server (NTRS)

    Rosenbaum, B.

    1977-01-01

    The Doppler difference method as applied to track the GEOS 3 spacecraft is discussed. In this method a pair of 2 GHz ground tracking stations simultaneously track a spacecraft beacon to generate an observable signal in which bias and instability of the carrier frequency cancel. The baselines are formed by the tracking sites at Bermuda, Rosman, and Merritt Island. Measurements were made to evaluate the effectiveness of the Doppler differencing procedure in tracking a beacon target with the high dynamic rate of the GEOS 3 orbit. Results indicate the precision of the differenced data to be at a level comparable to the conventional precise two way Doppler tracking.

  15. Digital Doppler measurement with spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.; Hinedi, Sami M.; Labelle, Remi C.; Bevan, Roland P.; Del Castillo, Hector M.; Chong, Dwayne C.

    1991-01-01

    Digital and analog phase-locked loop (PLL) receivers were operated in parallel, each tracking the residual carrier from a spacecraft. The PLL tracked the downlink carrier and measured its instantaneous phase. This information, combined with a knowledge of the uplink carrier and the transponder ratio, permitted the computation of a Doppler observable. In this way, two separate Doppler measurements were obtained for one observation window. The two receivers agreed on the magnitude of the Doppler effect to within 1 mHz. There was less jitter on the data from the digital receiver. This was due to its smaller noise bandwidth. The demonstration and its results are described.

  16. Multipoint photonic doppler velocimetry using optical lens elements

    SciTech Connect

    Frogget, Brent Copely; Romero, Vincent Todd

    2014-04-29

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

  17. Ductus Venosus Doppler Flow Velocity after Transplacental and Non-transplacental Amniocentesis during Midtrimester.

    PubMed

    Artunc Ulkumen, Burcu; Pala, Halil Gursoy; Baytur, Yesim Bulbul; Koyuncu, Faik Mumtaz

    2014-09-01

    We aimed to evaluate ductus venosus Doppler waveforms before and after amniocentesis in order to investigate any effect of amniocentesis on fetal myocardial hemodynamics. We also evaluated the umbilical artery, uterine artery and fetal mid-cerebral artery Doppler waveforms in order to investigate any relationship with ductus venosus Doppler changes. The study population consisted of 56 singleton pregnancies having genetic amniocentesis. Twenty seven of them had transplacental needle insertion; whereas 29 of them had non-transplacental amniocentesis. Uterine artery, umbilical artery, mid-cerebral artery and ductus venosus pulsatiliy index and resistance index were measured just before and after amniocentesis. Amniocentesis does not cause any significant changes in fetal ductus venosus Doppler waveforms. There is also no significant changes in uterine artery, umbilical artery, mid-cerebral artery pulsatility and resistance index. Amniocentesis-whether transplacental or not- does not cause any significant effect on fetal myocardial hemodynamics.

  18. Ductus Venosus Doppler Flow Velocity after Transplacental and Non-transplacental Amniocentesis during Midtrimester

    PubMed Central

    Ulkumen, Burcu Artunc; Pala, Halil Gursoy; Baytur, Yesim Bulbul; Koyuncu, Faik Mumtaz

    2014-01-01

    Objective: We aimed to evaluate ductus venosus Doppler waveforms before and after amniocentesis in order to investigate any effect of amniocentesis on fetal myocardial hemodynamics. We also evaluated the umbilical artery, uterine artery and fetal mid-cerebral artery Doppler waveforms in order to investigate any relationship with ductus venosus Doppler changes. Methods: The study population consisted of 56 singleton pregnancies having genetic amniocentesis. Twenty seven of them had transplacental needle insertion; whereas 29 of them had non-transplacental amniocentesis. Uterine artery, umbilical artery, mid-cerebral artery and ductus venosus pulsatiliy index and resistance index were measured just before and after amniocentesis. Results: Amniocentesis does not cause any significant changes in fetal ductus venosus Doppler waveforms. There is also no significant changes in uterine artery, umbilical artery, mid-cerebral artery pulsatility and resistance index. Conclusion: Amniocentesis-whether transplacental or not- does not cause any significant effect on fetal myocardial hemodynamics. PMID:25225513

  19. Evaluation of meteorological airborne Doppler radar

    NASA Technical Reports Server (NTRS)

    Hildebrand, P. H.; Mueller, C. K.

    1984-01-01

    This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  2. Theoretical analysis and experimental verification on optical rotational Doppler effect.

    PubMed

    Zhou, Hailong; Fu, Dongzhi; Dong, Jianji; Zhang, Pei; Zhang, Xinliang

    2016-05-02

    We present a theoretical model to sufficiently investigate the optical rotational Doppler effect based on modal expansion method. We find that the frequency shift content is only determined by the surface of spinning object and the reduced Doppler shift is linear to the difference of mode index between input and output orbital angular momentum (OAM) light, and linear to the rotating speed of spinning object as well. An experiment is carried out to verify the theoretical model. We explicitly suggest that the spatial spiral phase distribution of spinning object determines the frequency content. The theoretical model makes us better understand the physical processes of rotational Doppler effect, and thus has many related application fields, such as detection of rotating bodies, imaging of surface and measurement of OAM light.

  3. Pulsed Doppler on a vaginal probe. Necessity, convenience, or luxury?

    PubMed

    Schaaps, J P; Soyeur, D

    1989-06-01

    One hundred twenty-seven pregnancies were studied between 5 and 12 weeks of amenorrhea with Doppler ultrasound coupled with a vaginal probe. These biologically proven pregnancies had no clinical sign of abnormality; however, 29 were detected not to be evolving. Doppler signals were obtained from the embryonic heart, umbilical cord, trophoblastic crown, peritrophoblastic area, and from the uterine and ovarian arteries. In normally evolving pregnancies, no intratrophoblastic flow was detected, whereas it was present in all missed abortions. The peritrophoblastic area always generates a Doppler signal with an important diastolic component. The resistance index (RI) of uterine arteries was constant during the first trimester of pregnancy (RI = .77 +/- .15) and a protodiastolic notch was found in 58% of the cases. The combined use of these two modalities of examination was demonstrated. Although the clinical efficacy of the method has not yet been demonstrated, this combination of techniques opens new perspectives to echography and adds a dynamic dimension to morphologic studies.

  4. An introduction and guide to effective Doppler assessment.

    PubMed

    Benbow, Maureen

    2014-12-01

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

  5. Evaluation of factors influencing arterial Doppler waveforms in an in vitro flow phantom

    PubMed Central

    2017-01-01

    Purpose The aim of this study was to investigate factors that influence arterial Doppler waveforms in an in vitro phantom to provide a more accurate and comprehensive explanation of the Doppler signal. Methods A flow model was created using a pulsatile artificial heart, rubber or polyethylene tubes, a water tank, and a glass tube. Spectral Doppler tracings were obtained in multiple combinations of compliance, resistance, and pulse rate. Peak systolic velocity, minimum diastolic velocity, resistive index (RI), pulsatility index, early systolic acceleration time, and acceleration index were measured. On the basis of these measurements, the influences of the variables on the Doppler waveforms were analyzed. Results With increasing distal resistance, the RI increased in a relatively linear relationship. With increasing proximal resistance, the RI decreased. The pulsus tardus and parvus phenomenon was observed with a small acceleration index in the model with a higher grade of stenosis. An increase in the distal resistance masked the pulsus tardus and parvus phenomenon by increasing the acceleration index. Although this phenomenon occurred independently of compliance, changes in the compliance of proximal or distal tubes caused significant changes in the Doppler waveform. There was a reverse relationship between the RI and the pulse rate. Conclusion Resistance and compliance can alter the Doppler waveforms independently. The pulse rate is an extrinsic factor that also influences the RI. The compliance and distal resistance, as well as proximal resistance, influence the pulsus tardus and parvus phenomenon. PMID:27784154

  6. Doppler characteristics of sea clutter.

    SciTech Connect

    Raynal, Ann Marie; Doerry, Armin Walter

    2010-06-01

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

  7. Doppler tracking of planetary spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.

    1992-01-01

    This article concerns the measurement of Doppler shift on microwave links that connect planetary spacecraft with the Deep Space Network. Such measurements are made by tracking the Doppler effect with phase-locked loop receivers. A description of equipment and techniques as well as a summary of the appropriate mathematical models are given. The two-way Doppler shift is measured by transmitting a highly-stable microwave (uplink) carrier from a ground station, having the spacecraft coherently transpond this carrier, and using a phase-locked loop receiver at the ground station to track the returned (downlink) carrier. The largest sources of measurement error are usually plasma noise and thermal noise. The plasma noise, which may originate in the ionosphere or the solar corona, is discussed; and a technique to partially calibrate its effect, involving the use of two simultaneous downlink carriers that are coherently related, is described. Range measurements employing Doppler rate-aiding are also described.

  8. Dual-Doppler Feasibility Study

    NASA Technical Reports Server (NTRS)

    Huddleston, Lisa L.

    2012-01-01

    When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any

  9. [Color Doppler sonography of focal abdominal lesions].

    PubMed

    Licanin, Zoran; Lincender, Lidija; Djurović, V; Salihefendić, Nizama; Smajlović, Fahrudin

    2004-01-01

    rough border value. Values of DPI (Doppler perfusion index) over 0.3 and tumor index over 1.0 characterize primary, and lower values characterize secondary liver malignancies. In differentiation of benign and malign tumors of kidneys, besides the aspect of vascularisation, the maximal frequency altitude in tumor artery (the limit around 2.5 kHz) is very important. However, peripheral and penetrating blood vessels are most usually seen in RCC, less often in AML and bigger oncocytomas. CDS with contrast agent is very useful in making differential diagnosis of the focal lesions with 95% specificity for some lesions.

  10. Mathematical Models for Doppler Measurements

    NASA Technical Reports Server (NTRS)

    Lear, William M.

    1987-01-01

    Error analysis increases precision of navigation. Report presents improved mathematical models of analysis of Doppler measurements and measurement errors of spacecraft navigation. To take advantage of potential navigational accuracy of Doppler measurements, precise equations relate measured cycle count to position and velocity. Drifts and random variations in transmitter and receiver oscillator frequencies taken into account. Mathematical models also adapted to aircraft navigation, radar, sonar, lidar, and interferometry.

  11. Novel instantaneous laser Doppler velocimeter.

    PubMed

    Avidor, J M

    1974-02-01

    A laser Doppler velocimeter capable of directly measuring instantaneous velocities is described. The new LDV uses a novel detection technique based on the utilization of a static slightly defocused spherical Fabry-Perot interferometer used in conjunction with a special mask for the detection of instantaneous Doppler frequency shifts. The essential characteristics of this LDV are discussed, and such a system recently developed is described. Results of turbulent flow measurements show good agreement with data obtained using hot wire anemometry.

  12. High Resolution Doppler Lidar

    NASA Technical Reports Server (NTRS)

    1996-01-01

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

  13. Adaptive spectral doppler estimation.

    PubMed

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-04-01

    In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation 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 velocity 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 pulsating 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 performance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.

  14. High Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Hays, Paul B.

    1999-01-01

    This report summarizes the accomplishments of the High Resolution Doppler Imager (HRDI) on UARS spacecraft during the period 4/l/96 - 3/31/99. During this period, HRDI operation, data processing, and data analysis continued, and there was a high level of vitality in the HRDI project. The HRDI has been collecting data from the stratosphere, mesosphere, and lower thermosphere since instrument activation on October 1, 1991. The HRDI team has stressed three areas since operations commenced: 1) operation of the instrument in a manner which maximizes the quality and versatility of the collected data; 2) algorithm development and validation to produce a high-quality data product; and 3) scientific studies, primarily of the dynamics of the middle atmosphere. There has been no significant degradation in the HRDI instrument since operations began nearly 8 years ago. HRDI operations are fairly routine, although we have continued to look for ways to improve the quality of the scientific product, either by improving existing modes, or by designing new ones. The HRDI instrument has been programmed to collect data for new scientific studies, such as measurements of fluorescence from plants, measuring cloud top heights, and lower atmosphere H2O.

  15. Fetal renal pulsed Doppler waveform in prolonged pregnancies.

    PubMed

    Veille, J C; Penry, M; Mueller-Heubach, E

    1993-10-01

    Our purpose was to determine Doppler waveforms of the fetal human renal artery in prolonged pregnancy in the presence or absence of oligohydramnios. Fifty patients at or after 40 weeks were studied. Ultrasonography was performed to determine the amniotic fluid index by the four-quadrants technique. Two groups of patients were obtained on the basis of the amniotic fluid index. Group 1 had an amniotic fluid index > 5 (normal) (n = 33); group 2 had amniotic fluid index < or = 5 (oligohydramnios) (n = 17). Umbilical artery and fetal renal pulsed Doppler waveforms were determined and analyzed. The fetal renal artery systolic-to-diastolic ratio of the two groups was compared. Fetuses with a low amniotic fluid index had a significantly higher ratio. A significant negative correlation coefficient between amniotic fluid index and fetal renal systolic/diastolic ratio was found (r = -0.435 and p < 0.01). In prolonged pregnancies there is a significant relationship between the amniotic fluid index and the fetal renal systolic/diastolic ratio. In pregnancies associated with oligohydramnios the systolic/diastolic ratio is significantly higher than in those with normal amniotic fluid volume. These data suggest that intrarenal flow in prolonged pregnancies complicated with oligohydramnios is significantly different.

  16. [Echocardiographic and Doppler echocardiographic characterization of left ventricular diastolic function].

    PubMed

    Muscholl, M; Dennig, K; Kraus, F; Rudolph, W

    1990-12-01

    For noninvasive assessment of diastolic ventricular function, in addition to echocardiography, more recently, in particular, Doppler echocardiography has been employed. M-mode echocardiogram velocity curves for diameter changes as well as Doppler-echocardiographically registered velocity curves of mitral flow characterize the temporal changes of diastolic flow into the left ventricle. They represent the overall result of factors which influence diastolic filling and are functions of the temporal course of the pressure difference between left atrium and left ventricle. Registration of M-mode and Doppler echocardiograms: For determination of M-mode parameters which should describe left ventricular diastolic function, in addition to the motion of the mitral valve, the left ventricular contours of septum and posterior wall between mitral leaflets and papillary muscles are recorded together with the ECG. For evaluation of the index of atrial emptying, an M-mode registration is obtained from the region of the aortic root. Determination of the Doppler echocardiographic parameters is based on analysis of the blood flow velocity in the region of the mitral valve in the apical four-chamber view with the pulsed Doppler method. Additionally, simultaneous to the Doppler curve, a phonocardiogram is registered or, alternatively, a continuous-wave Doppler registration is obtained which delineates the left ventricular outflow signal and the artefact of mitral valve opening. Parameters for characterization of left ventricular diastolic filling: The first peak of the velocity curve of the diameter change in the M-mode echocardiogram corresponds with the maximal diameter change resulting from early-diastolic filling and the second peak with the maximal diameter change of the left ventricle associated with atrial filling. From this curve as well as the diameter curve relative to time and the mitral valve motion, the times for isovolumetric relaxation as well as the rapid, slow and

  17. [Ankle brachial index measurement].

    PubMed

    Rucigaj, Tanja Planinsek

    2014-10-01

    Ultrasound examinations are noninvasive diagnostic methods which, along with appropriate history and clinical examination, provide basic information on the etiology and spread of the disease, as well as on treatment options required in patients with chronic venous insufficiency and arterial flow impairment. Doppler flow meter offers useful data on venous blood return, primarily in great veins, while both deep and superficial veins as well as arteries can be visualized and data on venous and arterial hemodynamics obtained by duplex ultrasonography. In addition, Doppler flow meter provides data on the peripheral arterial system action through ankle brachial index measurement, which will guide the choice of compression therapy when deciding on the treatment of peripheral arterial disease and mixed arteriovenous leg ulcers. However, diagnosis of arterial insufficiency requires additional examinations.

  18. Planetary Doppler Imaging

    NASA Astrophysics Data System (ADS)

    Murphy, N.; Jefferies, S.; Hart, M.; Hubbard, W. B.; Showman, A. P.; Hernandez, G.; Rudd, L.

    2014-12-01

    Determining the internal structure of the solar system's gas and ice giant planets is key to understanding their formation and evolution (Hubbard et al., 1999, 2002, Guillot 2005), and in turn the formation and evolution of the solar system. While internal structure can be constrained theoretically, measurements of internal density distributions are needed to uncover the details of the deep interior where significant ambiguities exist. To date the interiors of giant planets have been probed by measuring gravitational moments using spacecraft passing close to, or in orbit around the planet. Gravity measurements are effective in determining structure in the outer envelope of a planet, and also probing dynamics (e.g. the Cassini and Juno missions), but are less effective in probing deep structure or the presence of discrete boundaries. A promising technique for overcoming this limitation is planetary seismology (analogous to helioseismology in the solar case), postulated by Vorontsov, 1976. Using trapped pressure waves to probe giant planet interiors allows insight into the density and temperature distribution (via the sound speed) down to the planetary core, and is also sensitive to sharp boundaries, for example at the molecular to metallic hydrogen transition or at the core-envelope interface. Detecting such boundaries is not only important in understanding the overall structure of the planet, but also has implications for our understanding of the basic properties of matter at extreme pressures. Recent Doppler measurements of Jupiter by Gaulme et al (2011) claimed a promising detection of trapped oscillations, while Hedman and Nicholson (2013) have shown that trapped waves in Saturn cause detectable perturbations in Saturn's C ring. Both these papers have fueled interest in using seismology as a tool for studying the solar system's giant planets. To fully exploit planetary seismology as a tool for understanding giant planet structure, measurements need to be made

  19. Laser Doppler systems in atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Murty, S. S. R.

    1976-01-01

    The loss of heterodyne signal power for the Marshall Space Flight Center laser Doppler system due to the random changes in the atmospheric index of refraction is investigated. The current status in the physics of low energy laser propagation through turbulent atmosphere is presented. The analysis and approximate evaluation of the loss of the heterodyne signal power due to the atmospheric absorption, scattering, and turbulence are estimated for the conditions of the January 1973 flight tests. Theoretical and experimental signal to noise values are compared. Maximum and minimum values of the atmospheric attenuation over a two way path of 20 km range are calculated as a function of altitude using models of atmosphere, aerosol concentration, and turbulence.

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

    PubMed

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

    2013-01-01

    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.

  1. Diagnosis of adnexal malignancies by using color Doppler energy imaging as a secondary test in persistent masses.

    PubMed

    Guerriero, S; Ajossa, S; Risalvato, A; Lai, M P; Mais, V; Angiolucci, M; Melis, G B

    1998-04-01

    The purpose of this prospective study was to compare the accuracy of B-mode transvaginal ultrasonography alone and in combination with color Doppler energy (or power Doppler) imaging in differentiating benign from malignant adnexal masses. A total of 192 consecutive persistent adnexal masses (159 benign, 33 malignant) were studied before surgery by B-mode transvaginal ultrasonography with and without color Doppler energy. In addition, CA-125 plasma levels were determined and spectral Doppler analysis was performed. By color Doppler energy imaging, a mass was considered malignant when arterial flow was visualized in an echogenic portion of a mass defined as malignant by B-mode. Intratumoral arterial blood flow could be readily detected by color Doppler energy imaging in all malignant tumors and in 94% of the benign tumors. The combined use of transvaginal B-mode ultrasonography and color Doppler energy imaging has greater accuracy in the diagnosis of ovarian malignancies than transvaginal ultrasonography alone (value of kappa: 0.81 and 0.63, respectively), reducing the number of false-positive results. The use of spectral Doppler analysis was of limited diagnostic value, with a kappa value of 0.17 for the pulsatility index (< 1) and of 0.41 for the resistance index (< 0.4). Also, the association with CA-125 increased the number of false-negative results. In conclusion, the use of color Doppler energy imaging seems to be a useful secondary test when a mass is suspected to be malignant by B-mode ultrasonography.

  2. A Fisheye Lens as a Photonic Doppler Velocimetry Probe

    SciTech Connect

    Frogget, B. C.

    2012-08-16

    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.

  3. Differential Doppler as a diagnostic

    SciTech Connect

    Dzieciuch, M.; Munk, W. )

    1994-10-01

    Differential Doppler compression and travel time of individual peaks in the arrival sequence (relative to an overall average) are measured for the 5500-km acoustic transmissions from a moving source at Heard Island to Christmas (Crab) Island. The differentials cannot be explained by simple adiabatic propagation models. A hybrid theory, coupling polar and temperate models at the Antarctic Front can account for some of the qualitative features. Differential Doppler could be a useful tool for identifying ray arrivals. 10 refs., 11 figs., 3 tabs.

  4. Continuous wave ultrasonic Doppler tomography

    PubMed Central

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

    2011-01-01

    In continuous wave ultrasonic Doppler tomography (DT), the ultrasonic beam moves relative to the scanned object to acquire Doppler-shifted frequency spectra which correspond to cross-range projections of the scattering and reflecting structures within the object. The relative motion can be circular or linear. These data are then backprojected to reconstruct the two-dimensional image of the object cross section. By using coherent processing, the spatial resolution of ultrasonic DT is close to an order of magnitude better than that of traditional pulse-echo imaging at the same ultrasound frequency. PMID:22866236

  5. [Doppler echocardiographic diagnosis and evaluation of tricuspid regurgitation].

    PubMed

    Blanchard, D; Diébold, B; Guermonprez, J L; Chitour, Z; Née, M; Péronneau, P; Forman, J; Maurice, P

    1982-12-01

    The reliability of pulsed Doppler echocardiography in the diagnosis and quantification of tricuspid regurgitation was assessed by analysis of blood flow in the inferior vena cava in 28 patients. The inferior vena caval flow was sampled in the retrohepatic portion of the vessel from the subxiphoid region. Recordings from 10 normal patients were used to define criteria of normality. This was characterised by two anterograde components (one systolic and one diastolic); atrial contraction gave rise to an end diastolic retrograde component. In tricuspid incompetence, retrograde systolic blood flow was recorded. A Doppler index was calculated from the ratio of the maximal amplitude of systolic reflux to the maximal amplitude of anterograde diastolic flow. In the absence of tricuspid regurgitation, this index approximated 0. The average of this ratio over 10 consecutive beats was compared with the semi quantitative assessment of tricuspid regurgitation from selective right ventricular angiography. There were no false positive results, specificity was, therefore, 100 p. 100. Six minimal regurgitations were not detected: sensitivity was therefore 74 p. 100. All moderate and severe regurgitations were detected, and the sensitivity for these cases was 100 p. 100. There was a close correlation (R = 0,89, p less than 0,01) between the Doppler index and the degree of regurgitation assessed by selective right ventricular angiography.

  6. Doppler Ultrasound: What Is It Used for?

    MedlinePlus

    ... in your neck (carotid artery stenosis) A Doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). During a Doppler ultrasound, a technician trained in ultrasound imaging (sonographer) presses ...

  7. Understanding Doppler Broadening of Gamma Rays

    SciTech Connect

    Rawool-Sullivan, Mohini; Sullivan, John P.

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  8. Doppler observations of solar rotation

    NASA Technical Reports Server (NTRS)

    Scherrer, P. H.; Wilcox, J. M.

    1980-01-01

    Daily observations of the photospheric equatorial rotation rate using the Doppler effect are made at the Stanford Solar Observatory. These observations show no variations in the rotation rate that exceed the observational error of about 1%. The average rotation rate is indistinguishable from that of sunspots and large-scale magnetic field structures.

  9. Doppler Imaging of EI Eridani

    NASA Astrophysics Data System (ADS)

    Washuettl, Albert; Strassmeier, Klaus G.; Collier-Cameron, Andrew

    We present Doppler images of the rapidly rotating active close binary star EI Eridani. Several Doppler images have been produced since 1984 making use of different versions of the Doppler imaging technique. They all show high-latitude spots surrounding or covering the rotational pole as well as some smaller spots on lower latitudes. The high-latitude/polar spot seems to be long-lived (at least a decade) but changes its shape on comparatively short timescales (of the order of one month). From time to time spots along the stellar equator also occur, but their lifetimes tend to be relatively short (weeks). Furthermore, long-term photometric observations revealed the existence of a magnetic cycle which has been estimated to be around 11 years. We also present time-resolved Doppler images from EI Eri obtained at McMath/NSO in fall 1996 during 70 consecutive nights. The final aim of this program is to investigate the spot evolution over the whole activity cycle.

  10. Doppler observations of solar rotation

    NASA Technical Reports Server (NTRS)

    Scherrer, P. H.

    1980-01-01

    Daily observations of the photospheric equatorial rotation rate using the Doppler effect mode at the Sanford Solar Observatory are presented. These observations show no variations in the rotation rate that exceed the observational error of about one percent. The average rotation rate is indistinguishable from that of sunspots and large scale magnetic field structures.

  11. Doppler observations of solar rotation

    NASA Technical Reports Server (NTRS)

    Scherrer, P. H.; Wilcox, J. M.

    1980-01-01

    Daily observations of the photospheric equatorial rotation rate using the Doppler effect are made at the Stanford Solar Observatory. These observations show no variations in the rotation rate that exceed the observational error of about 1%. The average rotation rate is indistinguishable from that of sunspots and large-scale magnetic field structures.

  12. The Doppler Effect--A New Approach

    ERIC Educational Resources Information Center

    Allen, J.

    1973-01-01

    Discusses the Doppler effect as it applies to different situations, such as a stationary source of sound with the observer moving, a stationary observer, and the sound source and observer both moving. Police radar, satellite surveillance radar, radar astronomy, and the Doppler navigator, are discussed as applications of Doppler shift. (JR)

  13. The Doppler Effect--A New Approach

    ERIC Educational Resources Information Center

    Allen, J.

    1973-01-01

    Discusses the Doppler effect as it applies to different situations, such as a stationary source of sound with the observer moving, a stationary observer, and the sound source and observer both moving. Police radar, satellite surveillance radar, radar astronomy, and the Doppler navigator, are discussed as applications of Doppler shift. (JR)

  14. Human polarimetric micro-doppler

    NASA Astrophysics Data System (ADS)

    Tahmoush, David; Silvious, Jerry

    2011-06-01

    Modern radars can pick up target motions other than just the principle target Doppler; they pick out the small micro-Doppler variations as well. These can be used to visually identify both the target type as well as the target activity. We model and measure some of the micro-Doppler motions that are amenable to polarimetric measurement. Understanding the capabilities and limitations of radar systems that utilize micro-Doppler to measure human characteristics is important for improving the effectiveness of these systems at securing areas. In security applications one would like to observe humans unobtrusively and without privacy issues, which make radar an effective approach. In this paper we focus on the characteristics of radar systems designed for the estimation of human motion for the determination of whether someone is loaded. Radar can be used to measure the direction, distance, and radial velocity of a walking person as a function of time. Detailed radar processing can reveal more characteristics of the walking human. The parts of the human body do not move with constant radial velocity; the small micro-Doppler signatures are timevarying and therefore analysis techniques can be used to obtain more characteristics. Looking for modulations of the radar return from arms, legs, and even body sway are being assessed by researchers. We analyze these techniques and focus on the improved performance that fully polarimetric radar techniques can add. We perform simulations and fully polarimetric measurements of the varying micro-Doppler signatures of humans as a function of elevation angle and azimuthal angle in order to try to optimize this type of system for the detection of arm motion, especially for the determination of whether someone is carrying something in their arms. The arm is often bent at the elbow, providing a surface similar to a dihedral. This is distinct from the more planar surfaces of the body and allows us to separate the signals from the arm (and

  15. Doppler velocimetric parameters of the testicular artery in healthy dogs.

    PubMed

    de Souza, Mírley Barbosa; da Cunha Barbosa, Claudia; Pereira, Barbara Sucupira; Monteiro, Cynthia Levi Baratta; Pinto, José Nicodemos; Linhares, Jussiara Candeira Spíndola; da Silva, Lúcia Daniel Machado

    2014-06-01

    This study aimed to examine the Doppler velocimetric pattern of the testicular artery of small dogs in two different locations. Testes of 21 dogs were evaluated by two-dimensional ultrasonography to measure testicular volume and by Doppler ultrasonography to record the velocimetric patterns of the testicular artery in the spermatic cord and marginal location. The volume of left testes (4.70 ± 1.22 cm(3)) was significantly higher than the volume of the right testes (4.45 ± 1.17 cm(3)). Peak systolic velocity (PSV) of the left spermatic cord was significantly higher than the right side. End-diastolic velocity was significantly higher in the marginal artery than the spermatic cord on both sides; however, resistance and pulsatility indexes were significantly lower in the marginal artery. Results demonstrate the viability of Doppler ultrasonography for characterization of the testicular artery in small dogs and Doppler velocimetric values vary according to the location of measurement along the artery.

  16. Doppler ultrasound and renal artery stenosis: An overview.

    PubMed

    Granata, A; Fiorini, F; Andrulli, S; Logias, F; Gallieni, M; Romano, G; Sicurezza, E; Fiore, C E

    2009-12-01

    Renovascular disease is a complex disorder, most commonly caused by fibromuscular dysplasia and atherosclerotic diseases. It can be found in one of three forms: asymptomatic renal artery stenosis (RAS), renovascular hypertension, and ischemic nephropathy. Particularly, the atherosclerotic form is a progressive disease that may lead to gradual and silent loss of renal function. Thus, early diagnosis of RAS is an important clinical objective since interventional therapy may improve or cure hypertension and preserve renal function. Screening for RAS is indicated in suspected renovascular hypertension or ischemic nephropathy, in order to identify patients in whom an endoluminal or surgical revascularization is advisable. Screening tests for RAS have improved considerably over the last decade. While captopril renography was widely used in the past, Doppler ultrasound (US) of the renal arteries (RAs), angio-CT, or magnetic resonance angiography (MRA) have replaced other modalities and they are now considered the screening tests of choice. An arteriogram is rarely needed for diagnostic purposes only. Color-Doppler US (CDUS) is a noninvasive, repeatable, relatively inexpensive diagnostic procedure which can accurately screen for renovascular diseases if performed by an expert. Moreover, the evaluation of the resistive index (RI) at Doppler US may be very useful in RAS affected patients for predicting the response to revascularization. However, when a discrepancy exists between clinical data and the results of Doppler US, additional tests are mandatory.

  17. Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry

    SciTech Connect

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

    2006-05-04

    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.

  18. Pulse Doppler ultrasound as a tool for the diagnosis of chronic testicular dysfunction in stallions

    PubMed Central

    Ortiz-Rodriguez, Jose M.; Anel-Lopez, Luis; Martín-Muñoz, Patricia; Álvarez, Mercedes; Gaitskell-Phillips, Gemma; Anel, Luis; Rodríguez-Medina, Pedro; Peña, Fernando J.

    2017-01-01

    Testicular function is particularly susceptible to vascular insult, resulting in a negative impact on sperm production and quality of the ejaculate. A prompt diagnosis of testicular dysfunction enables implementation of appropriate treatment, hence improving fertility forecasts for stallions. The present research aims to: (1) assess if Doppler ultrasonography is a good tool to diagnose stallions with testicular dysfunction; (2) to study the relationship between Doppler parameters of the testicular artery and those of sperm quality assessed by flow cytometry and (3) to establish cut off values to differentiate fertile stallions from those with pathologies causing testicular dysfunction. A total of 10 stallions (n: 7 healthy stallions and n: 3 sub-fertile stallions) were used in this study. Two ejaculates per stallion were collected and preserved at 5°C in a commercial extender. The semen was evaluated at T0, T24 and T48h by flow cytometry. Integrity and viability of sperm (YoPro®-1/EthD-1), mitochondrial activity (MitoTracker® Deep Red FM) and the DNA fragmentation index (Sperm Chromatin Structure Assay) were assessed. Doppler parameters were measured at three different locations on the testicular artery (Supratesticular artery (SA); Capsular artery (CA) and Intratesticular artery (IA)). The Doppler parameters calculated were: Resistive Index (RI), Pulsatility Index (PI), Peak Systolic Velocity (PSV), End Diastolic Velocity (EDV), Time Average Maximum Velocity (TAMV), Total Arterial Blood Flow (TABF) and TABF rate. The capsular artery was the most reliable location to carry out spectral Doppler assessment, since blood flow parameters of this artery were most closely correlated with sperm quality parameters. Significant differences in all the Doppler parameters studied were observed between fertile and subfertile stallions (p ≤ 0.05). The principal components analysis assay determined that fertile stallions are characterized by high EDV, TAMV, TABF and TABF rate

  19. Association between uterine artery Doppler blood flow changes and arterial wall elasticity in pregnant women.

    PubMed

    von Wowern, Emma; Andersson, Jakob; Skarping, Ida Dalene; Howie, Maria Teresa; Olofsson, Per

    2017-10-01

    Uterine artery (UtA) Doppler velocimetry changes and increased arterial stiffness are associated with preeclampsia. We aimed to investigate the relation between UtA velocimetry changes and arterial stiffness in pregnant women. Doppler velocimetry and photoplethysmographic digital pulse wave analysis (DPA) were performed in 173 pregnant women in the second or the third trimester, where UtA Doppler pulsatility index (PI), diastolic notching, and UtA score (UAS) combining notching and high PI were calculated. DPA stiffness parameters representing large arteries were ejection elasticity index (EEI) and b/a, small arteries dicrotic index (DI) and d/a, and global stiffness the aging index (AI). One hundred and thirty women had normal Doppler and 43 had diastolic notching, of whom nine had high PI. DI indicated increased stiffness in small arteries when notching was present (p = 0.044) and showed a significant but weak correlation to UAS (p = 0.025, tau 0.12). EEI and b/a indicated increased large artery stiffness (p ≤0.014), d/a small artery stiffness (p = 0.023), and AI a systemic stiffness (p = 0.040) when high PI. High UtA PI was associated with increased systemic arterial stiffness, whereas notching was related to increased stiffness in small arteries only. This indicates pathophysiological differences between the two Doppler parameters.

  20. Amplitude-coded color doppler: clinical applications.

    PubMed

    Turetschek, K; Kollmann, C; Dorffner, R; Wunderbaldinger, P; Mostbeck, G

    1999-01-01

    Amplitude-coded color Doppler sonography (ACD) has become an useful adjunct to gray-scale US and conventional color Doppler sonography (CD) for the assessment of vascular diseases and pathologic conditions that might affect or alter tissue vascularization or perfusion. Basically, all US units that generate conventional color Doppler information through autocorrelation technique are capable of displaying ACD. This technique is also referred to as power Doppler, amplitude-mode color Doppler US, color Doppler energy (CDE), or US angiography. Amplitude-coded color Doppler sonography has already emerged as a valuable adjunct to conventional CD, particularly for evaluating flow in parts of the body where CD signal is weak because of slow flow, small blood vessels, or both.

  1. Defect Tolerance to Intolerance in the Vacancy-Ordered Double Perovskite Semiconductors Cs2SnI6 and Cs2TeI6.

    PubMed

    Maughan, Annalise E; Ganose, Alex M; Bordelon, Mitchell M; Miller, Elisa M; Scanlon, David O; Neilson, James R

    2016-07-13

    Vacancy-ordered double perovskites of the general formula A2BX6 are a family of perovskite derivatives composed of a face-centered lattice of nearly isolated [BX6] units with A-site cations occupying the cuboctahedral voids. Despite the presence of isolated octahedral units, the close-packed iodide lattice provides significant electronic dispersion, such that Cs2SnI6 has recently been explored for applications in photovoltaic devices. To elucidate the structure-property relationships of these materials, we have synthesized solid-solution Cs2Sn1-xTexI6. However, even though tellurium substitution increases electronic dispersion via closer I-I contact distances, the substitution experimentally yields insulating behavior from a significant decrease in carrier concentration and mobility. Density functional calculations of native defects in Cs2SnI6 reveal that iodine vacancies exhibit a low enthalpy of formation, and that the defect energy level is a shallow donor to the conduction band rendering the material tolerant to these defect states. The increased covalency of Te-I bonding renders the formation of iodine vacancy states unfavorable and is responsible for the reduction in conductivity upon Te substitution. Additionally, Cs2TeI6 is intolerant to the formation of these defects, because the defect level occurs deep within the band gap and thus localizes potential mobile charge carriers. In these vacancy-ordered double perovskites, the close-packed lattice of iodine provides significant electronic dispersion, while the interaction of the B- and X-site ions dictates the properties as they pertain to electronic structure and defect tolerance. This simplified perspective based on extensive experimental and theoretical analysis provides a platform from which to understand structure-property relationships in functional perovskite halides.

  2. Soil and building material as main sources of indoor radon in Băiţa-Ştei radon prone area (Romania).

    PubMed

    Cosma, Constantin; Cucoş-Dinu, Alexandra; Papp, Botond; Begy, Robert; Sainz, Carlos

    2013-02-01

    Radon contributes to over than 50% of the natural radiation dose received by people. In radon risk areas this contribution can be as high as 90-95%, leading to an exposure to natural radiation 5-10 times higher than normal. This work presents results from radon measurements (indoor, soil and exhalation from building materials) in Băiţa-Ştei, a former uranium exploitation area in NW Romania. In this region, indoor radon concentrations found were as high as 5000 Bq m(-3) and soil radon levels ranged from 20 to 500 kBq m(-3). An important contribution from building materials to indoor radon was also observed. Our results indicate two independent sources of indoor radon in the surveyed houses of this region. One source is coming from the soil and regular building materials, and the second source being uranium waste and local radium reached material used in building construction. The soil as source of indoor radon shows high radon potential in 80% of the investigated area. Some local building materials reveal high radon exhalation rate (up to 80 mBq kg(-1) h(-1) from a sandy-gravel material, ten times higher than normal material). These measurements were used for the radon risk classification of this area by combining the radon potential of the soil with the additional component from building materials. Our results indicate that Băiţa-Ştei area can be categorized as a radon prone area. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  3. Right ventricular diastolic dysfunction in arterial systemic hypertension: analysis by pulsed tissue Doppler.

    PubMed

    Cicala, S; Galderisi, M; Caso, P; Petrocelli, A; D'Errico, A; de Divitiis, O; Calabrò, R

    2002-06-01

    This study analyses right ventricular longitudinal function in arterial systemic hypertension by pulsed tissue Doppler. Thirty normotensives and 30 hypertensives, free of cardiac drugs, underwent standard Doppler echocardiography and pulsed tissue Doppler of right ventricular lateral tricuspid annulus and left ventricular lateral mitral annulus. By tissue Doppler, systolic and diastolic measurements were obtained. Hypertensives had higher left ventricular mass and impaired Doppler diastolic indexes, without changes of global systolic function. Tissue Doppler showed reduction of right ventricular E/A ratio and prolongation of relaxation time in comparison with controls (both P<0.00001). In the overall population, the length of tissue Doppler derived right ventricular relaxation time was positively related to right ventricular anterior wall thickness while right ventricular E/A ratio was positively related to E/A ratio of left ventricular mitral annulus (both P<0.00001). These relations remained significant even after adjusting for clinical and echocardiographic confounders by separate multivariate models. Arterial systemic hypertension is associated to right ventricular longitudinal diastolic dysfunction. This dysfunction involves the prolongation of active relaxation, which is independently associated with the degree of right ventricular hypertrophy and the impairment of passive wall properties, which is mainly due to ventricular interaction occurring under left ventricular pressure overload conditions. Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.

  4. Differential diagnosis of prerenal azotemia from acute tubular necrosis and prediction of recovery by Doppler ultrasound.

    PubMed

    Izumi, M; Sugiura, T; Nakamura, H; Nagatoya, K; Imai, E; Hori, M

    2000-04-01

    Acute renal failure (ARF) is a life-threatening disease that often causes multiple organ dysfunction. The accurate and rapid diagnosis of the cause of ARF is particularly important for selecting the appropriate therapy. Ultrasound Doppler is a noninvasive diagnostic method that has recently been introduced to clinical nephrology. We report the diagnostic value of Doppler ultrasound in differentiating acute tubular necrosis (ATN) from prerenal azotemia by comparing this study with the fractional excretion of sodium (FENa), renal failure index (RFI), and urinary/serum creatinine (Cr) ratio. Doppler ultrasound was able to differentiate prerenal azotemia from ATN, equivalent to FENa, RFI, and the urinary/serum Cr ratio. Doppler ultrasound does not require blood or urine samples and can be performed at the bedside. Of note, Doppler is unaffected by changes in Na or Cr in urine or serum after diuretics or hemodialysis. Furthermore, one can predict recovery from ATN by Doppler findings. Thus, we consider Doppler ultrasound an effective diagnostic tool in ARF.

  5. Pathological prenatal Doppler sonography findings and their association with neonatal cranial ultrasound abnormalities in a high risk collective.

    PubMed

    Meyberg-Solomayer, G C; Soen, M; Speer, R; Poets, C; Goelz, R; Wallwiener, D; Solomayer, E-F

    2008-08-01

    The aim of this study was to evaluate whether prenatal Doppler ultrasound plays a role in the risk assessment of neonatal abnormal cranial ultrasound findings (NACU). Doppler examinations of blood flow velocities in the umbilical artery (n = 132), the fetal middle cerebral artery (n = 96) and the ductus venosus (n = 46) were conducted in 132 consecutive high-risk cases. The cases were divided into three groups: normal (I), pathological (II) and highly pathological Doppler (III) results, according to the resistance index calculated and were assessed for any association between the Doppler groups and the short-term outcome of the neonate, especially NACU. A significant association was found between Doppler groups and gestational age at delivery, birth weight, length and head circumference, growth restriction, cesarean section rate, Apgar score and pH values. NACU was diagnosed significantly more often in the pathological (12.1%) and highly pathological (38.5%) Doppler groups than in the group with normal Doppler (1.7%; p < 0.001). Multivariate analysis showed that the Doppler groups (odds ratio 1.67, 95% confidence interval [CI] 1.14-2.84, p < 0.001) and gestational age at delivery (odds ratio 1.37, 95% CI 1.08-2.74; p < 0.001) were independent variables that could be used to predict NACU. The present study showed that a pathological prenatal Doppler result is highly predictive for NACU in addition to gestational age and can therefore be used for risk assessment.

  6. The calibration of Doppler receivers

    NASA Astrophysics Data System (ADS)

    Jaks, W.

    A study to determine the relative positions of the antennas of two simultaneously operating Doppler receivers and the systematic corrections needed for a given type of receiver is presented. The types of receivers included in the study are listed and results showing the differences between the geocentric coordinates of the antenna phase centers of the receivers are given. It is found that, for DOG receivers, each antenna phase center must be determined separately.

  7. Doppler Imaging of PW And

    NASA Astrophysics Data System (ADS)

    Kolbin, A. I.; Galeev, A. I.

    2017-06-01

    In this work we have investigated spottiness of the young active K2-dwarf PW And. The spottiness analysis was based on high resolution spectroscopic observations obtained by 1.5-m Russian-Turkish telescope on September-October, 2015. The least square deconvolution technique was used to increase S/N of analyzed line profiles. The reconstruction of the spots distribution was performed by developed Doppler imaging codes. It was found that spots concentrate at intermediate latitudes.

  8. Effect of method and parameters of spectral analysis on selected indices of simulated Doppler spectra.

    PubMed

    Kaluzynski, K; Palko, T

    1993-05-01

    The sensitivity of Doppler spectral indices (mean frequency, maximum frequency, spectral broadening index and turbulence intensity) to the conditions of spectral analysis (estimation method, data window, smoothing window or model order) increases with decreasing signal bandwidth and growing index complexity. The bias of spectral estimate has a more important effect on these indices than its variance. A too low order, in the case of autoregressive modeling and minimum variance methods, and excessive smoothing, in the case of the FFT method, result in increased errors of Doppler spectral indices. There is a trade-off between the errors resulting from a short data window and those due to insufficient temporal resolution.

  9. Doppler effect's contribution to ultrasonic modulation of multiply scattered coherent light: Monte Carlo modeling.

    PubMed

    Elazar, Jovan M; Steshenko, Oleg

    2008-01-15

    Modulation of light by ultrasound in turbid media is investigated by modified public domain software based on the Monte Carlo algorithm. Apart from the recognized modulation mechanisms, originating in scatterers' displacements and refractive index modulation, an additional mechanism, evolving from Doppler shift during photon scattering, is considered. Comparison of the relative contributions from all three mechanisms to light modulation by ultrasound is performed for different medium scattering properties and ultrasound frequencies. Refractive index modulation remains the strongest mechanism for light modulation by ultrasound, but for high ultrasound frequencies and for large scattering coefficients the Doppler effect can become dominant.

  10. Ultrasound imaging for the rheumatologist. XVII. Role of colour Doppler and power Doppler.

    PubMed

    Iagnocco, A; Epis, O; Delle Sedie, A; Meenagh, G; Filippucci, E; Riente, L; Scirè, C A; Montecucco, C; Bombardieri, S; Grassi, W; Valesini, G

    2008-01-01

    The use of Doppler ultrasound in rheumatology has grown in recent years. This is partly due to the increasing number of rheumatologists who perform US in their daily clinical practise and also to the technological advances of US systems. Both colour Doppler and power Doppler are used to evaluate the degree of intra- and peri-articular soft tissue inflammation. Moreover, Doppler US has been found to be of help in the assessment of vascular pathologies such as the vasculitides. In this review we provide an update of the data regarding the use of colour Doppler and power Doppler in rheumatology.

  11. Acute Effects of Lateral Thigh Foam Rolling on Arterial Tissue Perfusion Determined by Spectral Doppler and Power Doppler Ultrasound.

    PubMed

    Hotfiel, Thilo; Swoboda, Bernd; Krinner, Sebastian; Grim, Casper; Engelhardt, Martin; Uder, Michael; Heiss, Rafael U

    2017-04-01

    Hotfiel, T, Swoboda, B, Krinner, S, Grim, C, Engelhardt, M, Uder, M, and Heiss, R. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and power Doppler ultrasound. J Strength Cond Res 31(4): 893-900, 2017-Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age, 25 ± 2 years; height, 177 ± 9 cm; body weight, 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by 4 blindfolded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 and 30 minutes after intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly after foam rolling exercises compared with baseline (p ≤ 0.05). We detected a relative increase in Vmax of 73.6% (0 minutes) and 52.7% (30 minutes) (p < 0.001), in TAMx of 53.2% (p < 0.001) and 38.3% (p = 0.002), and in TAMn of 84.4% (p < 0.001) and 68.2% (p < 0.001). Semiquantitative power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 minutes compared with 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.

  12. Phase equilibria and the thermodynamic properties of saturated solid solutions of BiTeI, Bi2TeI, and Bi4TeI1.25 compounds of the AgI-Bi-Bi2Te3-BiTeI system

    NASA Astrophysics Data System (ADS)

    Moroz, M. V.; Prokhorenko, M. V.

    2016-07-01

    The phase equilibria of the Ag-Bi-Te-I system in the part AgI-Bi-Bi2Te3-BiTeI is studied in the interval of 500-540 K by means of physicochemical analysis. Thermodynamic properties of phases are determined via EMF. Potential-forming processes occur in electrochemical cells (ECCs) of the C|Ag|glass Ag3GeS3I|D|C structure (where C denotes inert (graphite) electrodes; Ag, D denotes ECC electrodes; D denotes four-phase alloys of the AgI-Bi-Bi2Te3-BiTeI system; and Ag3GeS3I glass is the selective Ag+ conducting membrane). Linear dependences of the EMFs of cells E(T) in the interval of 505-535 K are used to calculate the values of the thermodynamic functions of BiTeI, Bi2TeI, and Bi4TeI1.25 phases saturated over silver.

  13. Comparison of echocardiographic parameters to assess right ventricular function in pulmonary hypertension.

    PubMed

    Amano, Hirohisa; Abe, Shichiro; Hirose, Suguru; Waku, Ryutaro; Masuyama, Taiki; Sakuma, Masashi; Toyoda, Shigeru; Taguchi, Isao; Inoue, Teruo; Tei, Chuwa

    2017-05-19

    Although measurement of right ventricular ejection fraction (RVEF) may be relevant for evaluation of therapeutic efficacy and/or prognosis in patients with pulmonary hypertension, RVEF obtained by echocardiography has limited accuracy. In contrast, radionuclide and/or magnetic resonance imaging can measure RVEF more reliably. In this study, we investigated the relationship between RVEF measured by radionuclide angiography and the echocardiographic parameters that are recommended by the American Society of Echocardiography as representative of right heart function. There were 23 study participants with pulmonary hypertension who underwent radionuclide angiography and 2-dimensional and Doppler echocardiography (n = 30 measurements). RVEF measured by radionuclide angiography correlated with right ventricular Tei index (RV Tei index) measured by Doppler echocardiography (r = -0.601, P < 0.0005). Receiver operating characteristic curve analysis showed that an RV Tei index cut-off value of 0.371 was the best of predictor of RVEF ≤35% (area under the curve = 0.768, sensitivity = 0.857, selectivity = 0.667). Multiple regression analysis showed that RVEF was correlated with the RV Tei index, and this association was independent of other echocardiographic right ventricular function parameters (r = -0.644, P < 0.005). The RV Tei index measured by Doppler echocardiography may be an acceptable surrogate marker of RVEF in patients with pulmonary hypertension.

  14. Transcranial Doppler sonography in fulminant hepatic failure.

    PubMed

    Abdo, A; López, O; Fernández, A; Santos, J; Castillo, J; Castellanos, R; González, L; Gómez, F; Limonta, D

    2003-08-01

    The clinical course of patients with fulminant hepatic failure (FHF) is often worsened by the presence of cerebral edema and endocranial hypertension. In spite of the multiple studies using Transcranial Doppler Sonography (TCDS), few have shown the cerebral blood flow (CBF) pattern among patients with encephalopathy resulting from FHF. Our objective was to characterize the CBF pattern in these patients through the use of TCDS to provide therapeutic strategies. The TCDS pattern was assessed in five patients diagnosed with FHF and compared with a control group who displayed critical neurologic conditions not associated with FHF. Pulsatile index, systolic, diastolic, and mean velocity of the middle cerebral artery were measured. The mean age of patients with FHF was 45.4 years. One hundred percent were women, with viral hepatitis as the predominant etiology. A cerebral hypoperfusion pattern was found in 80% of the FHF group and 40% of the control group. In the former group there was no evidence of hyperemia, as there was among 20% of the control group. The mean values of velocity and pulsatile index were 36.6 cm/sec and 2.4, respectively, in the FHF group and 47.8 cm/s and 1.8 in the control group (P=0.268, P=0.402). FHF patients show a predominance of cerebral hypoperfusion pattern with mean velocities lower than normal values and an increased pulsatile index. We recommend that clinicians take appropriate measures to improve cerebral perfusion and avoid hypoxia. Hyperventilation as a first level measure is contraindicated.

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

    PubMed

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

    2015-02-01

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

  16. Cardiovascular transition to extrauterine life in growth-restricted neonates: relationship with prenatal Doppler findings.

    PubMed

    Turan, Sifa; Turan, Ozhan M; Salim, Mubadda; Berg, Christoph; Gembruch, Ulrich; Harman, Christopher R; Baschat, Ahmet A

    2013-01-01

    Cardiovascular status in fetal growth restriction (FGR) can be classified by the severity of individual Doppler abnormalities (early and late) or by the rate of clinical progression. We tested the hypothesis that aspects of the fetal cardiovascular status in FGR affect neonatal cardiovascular findings. FGR cases [abdominal circumference <5th percentile and an elevated umbilical (MCA) artery (UA) pulsatility index] had UA, middle cerebral artery and ductus venosus (DV) Doppler. Positive UA end-diastolic velocity and/or a low MCA pulsatility index denoted early and absent/reversed UA end-diastolic velocity, whereas an increased DV pulsatility index for veins denoted late responses. The rate of progression was classified into mild, progressive and severe. After delivery, shunt dynamics and blood flow across the patent ductus arteriosus (PDA), foramen ovale and atriaventricular valves, myocardial contractility and pharmacologic pressor requirement were noted at neonatal echocardiography. These findings were related to prenatal Doppler parameters. In 94 patients, only individual Doppler parameters related to neonatal echocardiographic findings. Absent/reversed UA DV significantly predicted PDA with right to left shunt (p = 0.016). The pressor need for cardiovascular instability was observed in neonates with abnormal prenatal DV Doppler and with lower birth weights delivered at earlier gestational age (p < 0.0001 for both). Pressor need was significantly related to neonatal death (Nagelkerke R² = 0.35, p = 0.002). A markedly abnormal UA Doppler predisposes growth-restricted neonates to persistence of fetal circulation associated with right to left shunting. Abnormal venous Doppler is a risk factor for cardiovascular instability which in turn significantly contributes to neonatal mortality. Further clarification of the neonatal cardiovascular transition may be helpful in guiding early neonatal assessment and management. Copyright © 2012 S. Karger AG, Basel.

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

    PubMed

    Carvalho, Cibele F; Chammas, Maria C

    2011-06-01

    Renal diseases are common in older cats. Decreased renal blood flow may be the first sign of dysfunction and can be evaluated by Doppler ultrasound. But previous studies suggest that the resistive index (RI) has a low sensitivity for detecting renal disease. Doppler waveforms of renal and intrarenal arteries demonstrate decreased blood flow before there are any changes in the RI. The purpose of this study was to evaluate the normal Doppler flowmetrics parameters of renal arteries (RAs), interlobar arteries (IAs) and abdominal aorta (AO) in adult healthy, Persian cats. Twenty-five Persian cats (13 females and 12 males with mean age of 30 months and an age range 12-60 months) with normal clinical examinations and biochemical tests and normal systemic blood pressure were given B-mode ultrasonographies in order to exclude all nephropathies, including polycystic kidney disease. All measurements were performed on both kidneys. Both kidneys (n=50) were examined by color mapping of the renal vasculature. Pulsed Doppler was used to examine both RAs, the IAs at cranial, middle and caudal sites, and the AO. The RI was calculated for all of the vessels. Early systolic acceleration (ESA) of RA and IA was obtained with Doppler spectral analysis. Furthermore, the ratio indices between RA/AO, and IA/RA velocities were calculated. The mean values of peak systolic velocity (PSV) and the diameter for AO were 53.17±13.46 cm/s and 0.38±0.08 cm, respectively. The mean RA diameter for all 50 kidneys was 0.15±0.02 cm. Considering the velocimetric values in both RAs, the mean PSV and RI that were obtained were 41.17±9.40 cm/s and 0.54±0.07. The RA had a mean ESA of 1.12±1.14 m/s(2) and the calculated upper limit of the reference value was 3.40 m/s(2). The mean renal-aortic ratio was 0.828±0.296. The IA showed PSV and RI values of 32.16±9.33 cm/s and 0.52±0.06, respectively. The mean ESA of all IAs was 0.73±0.61 m/s(2). The calculated upper limit of the reference value was 2.0m

  18. Performance Of A Doppler-Corrected MDPSK Detector

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.; Jedrey, Thomas C.; Hinedi, Sami; Agan, Martin J.

    1994-01-01

    Report presents theoretical analysis of effect of rate of change of Doppler shift of received multiple-differential-phase-shift-keyed (MDPSK) radio signal on performance of Doppler-corrected differential detector. In particular detector, phase of received signal corrected for Doppler shift by use of Doppler estimator designed to operate in presence of negligibly small Doppler rate.

  19. Equations for Bistatic Doppler Shift and Rate of Change of Doppler Shift of Dark Satellite Observations

    DTIC Science & Technology

    Equations are given for the doppler shift and rate of change of doppler shift for the bistatic case where an orbiting, nontransmitting earth... of change of doppler shift, satellite height, earth-center angle between the receiver and the satellite, and zenith angle from receiver to satellite are shown for a typical satellite, 1958 Alpha, Explorer I....have been computed, using transmitting and receiving sites of the Space Surveillance System. Plots of various relationships between doppler shift, rate

  20. [Doppler color in superficial adenopathies].

    PubMed

    Giovagnorio, F

    1999-03-01

    Superficial lymph nodes are frequently involved in different diseases. Their location makes them suitable for effective assessment with high-resolution US and color Doppler has been recently suggested as a tool for increasing sensitivity in lymph node studies. Thus, we investigated the main vascular patterns detectable in abnormal superficial lymph nodes. We evaluated 260 nodes in 180 adult patients; the nodes were located in the cervicofacial ring (78, 30%), internal jugular stations (104, 40%), and supraclavicular (44, 17%), axillary (21, 8%), and inguinal (13, 5%) stations. Color Doppler was performed with 7.5-13 MHz linear transducers, with parameters adjusted for slow-flow detection (5-6 MHz frequency, 700-900 Hz PRF, 50 Hz band filter, high color persistence). Disease assessment required fine-needle biopsy (95 nodes in 95 patients) and clinical follow-up (165 nodes in 85 patients). Fifty-five nodes (21%) presented acute and 130 (50%) chronic inflammation: 75 nodes (29%) were metastatic. The following vascular patterns were detected: a single vascular pole (type I) was seen in chronic inflammation (72% sensitivity, 86% specificity, 57% positive and 92% negative predictive value); an enlarged single vascular pole, with 2-3 enlarged branches (type II) in acute adenitis (80% sensitivity, 81% specificity, 78% positive and 83% negative predictive value); multiple vascular poles with many deformed and displaced branches converging centrally (type III) in metastases (76% sensitivity, 100% specificity, 100% positive and 91% negative predictive value). We conclude that color and power Doppler are useful integrations to B-mode US because they can detect specific signs of malignancy such as peripheral vascular poles and intranodal displacement of vessels.

  1. The age-related advancement of arterial disease measured by Doppler ultrasound diastolic flow analysis.

    PubMed

    Terenzi, T; Gallagher, D; DeMeersman, R; Beadle, E; Muller, D

    1993-10-01

    To quantify by A-mode Doppler sonography the age-related progression of arterial disease so that age dependent normal values may be established for the screening Doppler peripheral arterial exam. Arterial distensibility was assessed by A-mode Doppler diastolic flow analysis as a measure of atherogenesis. These values will increase the sensitivity and decrease the incidence of false-positive results when the Doppler exam is utilized to differentially diagnosis vascular and sciatic neurogenic claudication. The relationship between age and results from the standard ankle/arm index ultrasound pneumatic cuff examination was also analyzed. A two by three analysis of variance with orthogonal Helmert contrast codes and simple linear regression analysis was utilized for this cross-sectionally designed investigation. The dependent measures of diastolic flow analysis and ankle/arm pressure index were obtained within three nested successively increasing age groups. Chiropractic office. Studied were a total of 90 sedentary nonsmoking subjects, aged 23-79 yr, all of whom had normally accepted levels of serum glucose, cholesterol and blood pressure. Subjects were screened for evidence of aortic coarctation, myocardial infarction, tachyarrhythmia, aortic valve stenosis, mitral prolapse, hypertension, hypercholesterolemia, diabetes and peripheral occlusive arterial disease. Anthropometric measurements and percent body fat were obtained. A predictive oxygen consumption bike ergometer test was performed to obtain aerobic capacity. The commonly utilized standard ankle/arm index ultrasound pneumatic cuff examination and arterial diastolic flow analysis were performed with A-mode Doppler ultrasound on all subjects. These results demonstrate that a significant inverse linear relationship exists between aging and arterial compliance (p < .0001) in our population. Diastolic flow analysis had a greater sensitivity to arterial disease than the standard ankle/arm index ultrasound pneumatic

  2. A Fisheye Lens as a Photonic Doppler Velocimetry Probe

    SciTech Connect

    Frogget, B C; Cox, B C; DeVore, D O; Esquibel, D L; Frayer, D K; Furlanetto, M R; Holtkamp, D B; Kaufman, M I; Malone, R M; Romero, V T

    2012-09-01

    A new fisheye lens design is used as a miniature probe to measure the velocity distribution of an imploding surface along many lines of sight. Laser light, directed and scattered back along each beam on the surface, is Doppler shifted by the moving surface and collected into the launching fiber. The received light is mixed with reference laser light in each optical fiber in a technique called photonic Doppler velocimetry, providing a continuous time record. An array of single-mode optical fibers sends laser light through the fisheye lens. The lens consists of an index-matching positive element, two positive doublet groups, and two negative singlet elements. The optical design minimizes beam diameters, physical size, and back reflections for excellent signal collection. The fiber array projected through the fisheye lens provides many measurement points of surface coverage over a hemisphere with very little crosstalk. The probe measures surface movement with only a small encroachment into the center of the cavity. The fiber array is coupled to the index-matching element using index-matching gel. The array is bonded and sealed into a blast tube for ease of assembly and focusing. This configuration also allows the fiber array to be flat polished at a common object plane. In areas where increased measurement point density is desired, the fibers can be close packed. To further increase surface density coverage, smaller-diameter cladding optical fibers may be used.

  3. A fisheye lens as a photonic Doppler velocimetry probe

    NASA Astrophysics Data System (ADS)

    Frogget, Brent C.; Cata, Brian M.; Cox, Brian C.; DeVore, Douglas O.; Esquibel, David L.; Frayer, Daniel K.; Furlanetto, Michael R.; Holtkamp, David B.; Kaufman, Morris I.; Malone, Robert M.; Romero, Vincent T.

    A new fisheye lens design is used as a miniature probe to measure the velocity distribution of an imploding surface along many lines of sight. Laser light, directed and scattered back along each beam on the surface, is Doppler shifted by the moving surface and collected into the launching fiber. The received light is mixed with reference laser light in each optical fiber in a technique called photonic Doppler velocimetry, providing a continuous time record. An array of single-mode optical fibers sends laser light through the fisheye lens. The lens consists of an index-matching positive element, two positive doublet groups, and two negative singlet elements. The optical design minimizes beam diameters, physical size, and back reflections for excellent signal collection. The fiber array projected through the fisheye lens provides many measurement points of surface coverage over a hemisphere with very little crosstalk. The probe measures surface movement with only a small encroachment into the center of the cavity. The fiber array is coupled to the index-matching element using index-matching gel. The array is bonded and sealed into a blast tube for ease of assembly and focusing. This configuration also allows the fiber array to be flat polished at a common object plane. In areas where increased measurement point density is desired, the fibers can be close packed. To further increase surface density coverage, smaller-diameter cladding optical fibers may be used.

  4. Sevoflurane Used for Color Doppler Ultrasound Examination in Children.

    PubMed

    Fan, Conghai; Zhang, Fengchao; Huang, Xiaomei; Wen, Cheng; Shan, Chengjing

    2015-05-01

    The objective of this study is to investigate the feasibility of sevoflurane inhalation in pediatric color doppler ultrasound examination. In this study, 30 cases of children under 1 year were selected. They were all I or II levels according to American Society of Anesthesiology. Children with severe cyanotic congenital heart disease or severe pneumonia were excluded. All the children received anesthesia with sevoflurane. The University of Michigan Sedation Scale was assessed and bispectral index (BIS) was recorded before induction (T0), after induction (T1), when maintaining (T2), and when waking-up (T3). Blood pressure and heart rate were monitored during the color doppler ultrasound examination, the time to receive sedation examination and anesthesia recovery time were also recorded. (1) Score for UMSS was zero at T0 and 3 at T1; (2) BIS value was 93.18 ± 2.94 at T0 and decreased to 87.6 ± 3.9 at T1; (3) Blood pressure or heart rate did not decline obviously; (4) The time to receive sedation examination was 46.4 ± 13.1 s and anesthesia recovery time was 7.8 ± 5.3 min. In conclusion, sevoflurane can be used in pediatric color doppler ultrasound examination safely and effectively.

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

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

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

  6. Luminosity Dependence and Search Doppler

    NASA Technical Reports Server (NTRS)

    VanParadijs, Johannes A.

    1998-01-01

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

  7. Doppler ultrasound exam of an arm or leg

    MedlinePlus

    ... the risk of problems with the heart and circulatory system. Most smoking-related deaths are caused by cardiovascular problems, not lung cancer. Alternative Names Peripheral vascular disease - Doppler; PVD - Doppler; PAD - Doppler; Blockage of leg ...

  8. [Per partum acidosis: Interest and feasibility of cerebral Doppler during labor].

    PubMed

    Barrois, M; Chartier, M; Lecarpentier, E; Goffinet, F; Tsatsaris, V

    2016-09-01

    To evaluate feasibility and interest of fetal cerebral Doppler during labor and the link with fetal pH to predict perinatal fetal asphyxia. Our prospective study in a university perinatal center, included patients during labor. There were no risk factors during pregnancy and patients were included after 37 weeks of pregnancy. For each patient an ultrasound with cerebral Doppler was done concomitant to a fetal scalp blood sample. We collected maternal and fetal characteristics as well as cervix dilatation, fetal heart rate analysis and fetal presentation. Among 49 patients included over a period of 4 months, cerebral Doppler failed in 7 cases (11%). Majority of failure occurred at 10cm of dilatation (P=0.007, OR=14.1 [1.483; 709.1275]). Others factors like: maternal age, body mass index, parity, history of C-Section were not associated with higher rate of failure. We did not found either significant correlation between cerebral fetal Doppler and pH on fetal scalp blood sample (r=0.15) nor pH at cord blood sample (r=0.13). No threshold of cerebral Doppler is significant for fetal asphyxia prediction. Fetal cerebral Doppler is feasible during labor with a low rate of failure but not a good exam to predict fetal acidosis and asphyxia. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  9. Ultrafast Doppler reveals the mapping of cerebral vascular resistivity in neonates

    PubMed Central

    Demené, Charlie; Pernot, Mathieu; Biran, Valérie; Alison, Marianne; Fink, Mathias; Baud, Olivier; Tanter, Mickaël

    2014-01-01

    In vivo mapping of the full vasculature dynamics based on Ultrafast Doppler is showed noninvasively in the challenging case of the neonatal brain. Contrary to conventional pulsed-wave (PW) Doppler Ultrasound limited for >40 years to the estimation of vascular indices at a single location, the ultrafast frame rate (5,000 Hz) obtained using plane-wave transmissions leads to simultaneous estimation of full Doppler spectra in all pixels of wide field-of-view images within a single cardiac cycle and high sensitivity Doppler imaging. Consequently, 2D quantitative maps of the cerebro-vascular resistivity index (RI) are processed and found in agreement with local measurements obtained on large arteries of healthy neonates using conventional PW Doppler. Changes in 2D resistivity maps are monitored during recovery after therapeutic whole-body cooling of full-term neonates treated for hypoxic ischemic encephalopathy. Arterial and venous vessels are unambiguously differentiated on the basis of their distinct hemodynamics. The high spatial (250 × 250 μm2) and temporal resolution (<1 ms) of Ultrafast Doppler imaging combined with deep tissue penetration enable precise quantitative mapping of deep brain vascular dynamics and RI, which is far beyond the capabilities of any other imaging modality. PMID:24667916

  10. Airborne Differential Doppler Weather Radar

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  11. Airborne Differential Doppler Weather Radar

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  12. Indexing Images.

    ERIC Educational Resources Information Center

    Rasmussen, Edie M.

    1997-01-01

    Focuses on access to digital image collections by means of manual and automatic indexing. Contains six sections: (1) Studies of Image Systems and their Use; (2) Approaches to Indexing Images; (3) Image Attributes; (4) Concept-Based Indexing; (5) Content-Based Indexing; and (6) Browsing in Image Retrieval. Contains 105 references. (AEF)

  13. Color Doppler imaging in glaucoma patients with asymmetric optic cups.

    PubMed

    Costa, V P; Sergott, R C; Smith, M; Spaeth, G L; Wilson, R P; Moster, M R; Katz, L J; Schmidt, C M

    1994-01-01

    To evaluate the color Doppler imaging (CDI) parameters of the retrobulbar circulation, we performed color Doppler imaging in both eyes of 29 glaucomatous patients with asymmetric cups [asymmetry >0.3 cup/disc ratio (C/D)] and asymmetric visual field loss. We used the QAD-1 Color Doppler unit (Quantum Medical Systems Inc.) with a 7.5-MHz linear-phased transducer to calculate the pulsatility index, and the peak systolic, end diastolic, and average blood-flow velocities in the ophthalmic, central retinal, nasal, and temporal short posterior ciliary arteries of each eye. In a second analysis, we compared the results of a randomly selected eye of age- and sex-matched controls. Paired t tests did not show any significant difference between the blood-flow velocities of the more damaged and less damaged eyes when the entire 29-patient group was considered together. The power was adequate to detect a 1.0 cm/s difference in most of the analyzed vessels. Thirteen of the 29 patients had primary open-angle glaucoma (POAG), and the remaining eyes had pseudoexfoliation and low tension, pigmentary, and chronic angle-closure glaucoma. When compared to age- and sex-matched controls, the less damaged eyes of patients with POAG displayed reduced systolic, diastolic, and mean velocities (p < 0.05) in the ophthalmic artery. In comparison, the more damaged eyes revealed statistically reduced velocities in the ophthalmic artery, temporal short posterior ciliary artery, and in all the parameters for the mean values of the short posterior ciliary arteries (p < 0.05). More advanced optic nerve damage in patients with POAG correlated with more severe reductions of CDI parameters of the retrobulbar circulation of patients with asymmetric disease. Further clinical color Doppler correlations are now mandatory to determine whether these vascular changes are pathogenetically important or epiphenomena.

  14. Cerebral blood flow in the newborn infant: comparison of Doppler ultrasound and /sup 133/xenon clearance

    SciTech Connect

    Greisen, G.; Johansen, K.; Ellison, P.H.; Fredriksen, P.S.; Mali, J.; Friis-Hansen, B.

    1984-03-01

    Two techniques of Doppler ultrasound examination, continuous-wave and range-gated, applied to the anterior cerebral artery and to the internal carotid artery, were compared with /sup 133/xenon clearance after intravenous injection. Thirty-two sets of measurements were obtained in 16 newborn infants. The pulsatility index, the mean flow velocity, and the end-diastolic flow velocity were read from the Doppler recordings. Mean cerebral blood flow was estimated from the /sup 133/Xe clearance curves. The correlation coefficients between the Doppler and the /sup 133/Xe measurements ranged from 0.41 to 0.82. In the subset of 16 first measurements in each infant, there were no statistically significant differences between the correlation coefficients of the various Doppler ultrasound variables, but the correlation coefficients were consistently lower for the pulsatility index than for mean flow velocity or end-diastolic flow velocity, and they were consistently higher for the range-gated than for the continuous-wave Doppler technique.

  15. Diagnostic Accuracy of Transcranial Doppler for Brain Death Confirmation: Systematic Review and Meta-Analysis.

    PubMed

    Chang, J J; Tsivgoulis, G; Katsanos, A H; Malkoff, M D; Alexandrov, A V

    2016-03-01

    Transcranial Doppler is a useful ancillary test for brain death confirmation because it is safe, noninvasive, and done at the bedside. Transcranial Doppler confirms brain death by evaluating cerebral circulatory arrest. Case series studies have generally reported good correlations between transcranial Doppler confirmation of cerebral circulatory arrest and clinical confirmation of brain death. The purpose of this study is to evaluate the utility of transcranial Doppler as an ancillary test in brain death confirmation. We conducted a systematic review of the literature and a diagnostic test accuracy meta-analysis to compare the sensitivity and specificity of transcranial Doppler confirmation of cerebral circulatory arrest, by using clinical confirmation of brain death as the criterion standard. We identified 22 eligible studies (1671 patients total), dating from 1987 to 2014. Pooled sensitivity and specificity estimates from 12 study protocols that reported data for the calculation of both values were 0.90 (95% CI, 0.87-0.92) and 0.98 (95% CI, 0.96-0.99), respectively. Between-study differences in the diagnostic performance of transcranial Doppler were found for both sensitivity (I(2) = 76%; P < .001) and specificity (I(2) = 74.3%; P < .001). The threshold effect was not significant (Spearman r = -0.173; P = .612). The area under the curve with the corresponding standard error (SE) was 0.964 ± 0.018, while index Q test ± SE was estimated at 0.910 ± 0.028. The results of this meta-analysis suggest that transcranial Doppler is a highly accurate ancillary test for brain death confirmation. However, transcranial Doppler evaluates cerebral circulatory arrest rather than brain stem function, and this limitation needs to be taken into account when interpreting the results of this meta-analysis. © 2016 by American Journal of Neuroradiology.

  16. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-08-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  17. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    PubMed

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-08-31

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  18. Development of the doppler electron velocimeter: theory.

    SciTech Connect

    Reu, Phillip L.

    2007-03-01

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

  19. Laser Doppler dust devil measurements

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    A scanning laser doppler velocimeter (SLDV) system was used to detect, track, and measure the velocity flow field of naturally occurring tornado-like flows (dust devils) in the atmosphere. A general description of the dust devil phenomenon is given along with a description of the test program, measurement system, and data processing techniques used to collect information on the dust devil flow field. The general meteorological conditions occurring during the test program are also described, and the information collected on two selected dust devils are discussed in detail to show the type of information which can be obtained with a SLDV system. The results from these measurements agree well with those of other investigators and illustrate the potential for the SLDV in future endeavors.

  20. [Doppler ultrasound diagnosis in post-term pregnancy].

    PubMed

    Jörn, H; Funk, A; Fendel, H

    1993-09-01

    The capability of Doppler flow velocimetry to predict intrauterine growth retardation is well known. The increased morbidity and mortality rate of postterm newborns is also well known. The aim of our study was to examine if Doppler flow velocimetry is able to indicate foetal jeopardy in the postterm period. Flow velocimetry of the foetal descending aorta, the umbilical artery, the uterine arteries and in 59 cases also the foetal middle cerebral artery was obtained from 167 pregnancies after 40 completed weeks of gestation. We found significant changes of normal values in prolonged pregnancy compared to third trimester normal values, examining the mean velocity of the foetal descending aorta and the S/D-ratio of the umbilical artery. No clinically significant changes were found examining the S/D-ratio of the uterine arteries and the pulsatility index of the foetal middle cerebral artery. Daily examinations of the foetal descending aorta were carried out in 23 and of the umbilical artery in 19 cases during the last four days before delivery, and in 11 cases of the foetal middle cerebral artery during the last three days before delivery. We did not find significant changes in the medians of the mean velocity of the foetal aorta, of the S/D-ratio of the umbilical artery and of the pulsatility index of the foetal middle cerebral artery. Measurement of sensitivity and positive predictive value of the four arteries examined showed, that Doppler ultrasound could not predict small for date infants or Caesarean section because of foetal distress.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Staggered Multiple-PRF Ultrafast Color Doppler.

    PubMed

    Posada, Daniel; Poree, Jonathan; Pellissier, Arnaud; Chayer, Boris; Tournoux, Francois; Cloutier, Guy; Garcia, Damien

    2016-06-01

    Color Doppler imaging is an established pulsed ultrasound technique to visualize blood flow non-invasively. High-frame-rate (ultrafast) color Doppler, by emissions of plane or circular wavefronts, allows severalfold increase in frame rates. Conventional and ultrafast color Doppler are both limited by the range-velocity dilemma, which may result in velocity folding (aliasing) for large depths and/or large velocities. We investigated multiple pulse-repetition-frequency (PRF) emissions arranged in a series of staggered intervals to remove aliasing in ultrafast color Doppler. Staggered PRF is an emission process where time delays between successive pulse transmissions change in an alternating way. We tested staggered dual- and triple-PRF ultrafast color Doppler, 1) in vitro in a spinning disc and a free jet flow, and 2) in vivo in a human left ventricle. The in vitro results showed that the Nyquist velocity could be extended to up to 6 times the conventional limit. We found coefficients of determination r(2) ≥ 0.98 between the de-aliased and ground-truth velocities. Consistent de-aliased Doppler images were also obtained in the human left heart. Our results demonstrate that staggered multiple-PRF ultrafast color Doppler is efficient for high-velocity high-frame-rate blood flow imaging. This is particularly relevant for new developments in ultrasound imaging relying on accurate velocity measurements.

  2. Wideband radar micro-doppler applications

    NASA Astrophysics Data System (ADS)

    Tahmoush, Dave

    2013-05-01

    Wideband radar provides a significant improvement over traditional narrowband radars for micro-Doppler analysis because the high bandwidth can be used to separate many of the signals in range, allowing a simpler decomposition of the micro-Doppler signals. Recent wideband radar work has focused on micro-Doppler, but there is a point where the narrowband approach used to analyze the micro-Doppler signals breaks down. The effect is shown to be independent of frequency, but the error relative to the bandwidth is shown to be inversely proportional to the frequency and proportional to the velocity of the subject. This error can create a smearing effect in the observed Doppler if it is not corrected, leading to reduced signal-to-noise and the appearance of more diffuse targets in Doppler space. In range-space, wideband data can also break the subject into several range bins, affecting the observed signal to noise ratio. The possible applications of wideband micro-Doppler radar are also shown, including the separation of arm movement from human motion which implies that the arms are not encumbered.

  3. Rotational Doppler effect in nonlinear optics

    NASA Astrophysics Data System (ADS)

    Li, Guixin; Zentgraf, Thomas; Zhang, Shuang

    2016-08-01

    The translational Doppler effect of electromagnetic and sound waves has been successfully applied in measurements of the speed and direction of vehicles, astronomical objects and blood flow in human bodies, and for the Global Positioning System. The Doppler effect plays a key role for some important quantum phenomena such as the broadened emission spectra of atoms and has benefited cooling and trapping of atoms with laser light. Despite numerous successful applications of the translational Doppler effect, it fails to measure the rotation frequency of a spinning object when the probing wave propagates along its rotation axis. This constraint was circumvented by deploying the angular momentum of electromagnetic waves--the so-called rotational Doppler effect. Here, we report on the demonstration of rotational Doppler shift in nonlinear optics. The Doppler frequency shift is determined for the second harmonic generation of a circularly polarized beam passing through a spinning nonlinear optical crystal with three-fold rotational symmetry. We find that the second harmonic generation signal with circular polarization opposite to that of the fundamental beam experiences a Doppler shift of three times the rotation frequency of the optical crystal. This demonstration is of fundamental significance in nonlinear optics, as it provides us with insight into the interaction of light with moving media in the nonlinear optical regime.

  4. Comparison between ultrasonographic findings of benign and malignant canine mammary gland tumours using B-mode, colour Doppler, power Doppler and spectral Doppler.

    PubMed

    Soler, Marta; Dominguez, Elisabet; Lucas, Xiomara; Novellas, Rosa; Gomes-Coelho, Kassia Valeria; Espada, Yvonne; Agut, Amalia

    2016-08-01

    The aim of this study was to evaluate whether the comparison between the ultrasonographic features of canine mammary tumours, assessed by B-Mode, colour Doppler, power Doppler, spectral Doppler, and histopathologic features, would help to differentiate if a tumour is benign or malignant. Ultrasonographic examinations of 104 tumours were performed. Volume, margins, presence of a capsule, echotexture and presence and distribution of the vascular flow of the tumours were evaluated. All the tumours were surgically removed, submitted for histopathologic examination and classified in two groups: Group I (benign tumours) and Group II (malignant tumours). Echotexture was the only parameter evaluated by B-Mode ultrasonography where significant differences were found (p<0.01), with tumours in Group I being homogeneous and tumours in Group II presenting greater heterogeneity. Presence of vascular flow was observed in most of the tumours from both groups and no differences between them were found. Regarding flow distribution, significant differences were observed between groups (p<0.05). In benign tumours, the most common vascular pattern was the peripheral, showing significant differences (p<0.05) compared to mixed and central patterns. In malignant tumours the mixed pattern was the most frequent. Also significant differences among other patterns (peripheral and central) were found. Concerning vascular resistivity and pulsatility indexes, there were no significant differences between the two groups. The echotexture and type of vascular flow pattern of canine mammary gland tumours may help, in a first examination of the tumour, to differentiate between benign and malignant tumours; however to reach a definitive diagnosis histological study is required. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Color Doppler imaging of untreated and irradiated choroidal melanomas.

    PubMed

    Regan, S; Egan, K M; Hart, L; Gragoudas, E S

    2001-01-01

    We examined untreated and irradiated choroidal melanomas with color Doppler imaging (CDI), a noninvasive method providing quantitative measures of blood flow, to determine if the tumor vessel damage associated with irradiation can be detected using this technology. CDI was performed on 122 untreated and 76 previously irradiated tumors using a Q2000 color Doppler ultrasound unit. Spectral analysis was performed on all detectable vascular regions within the tumor to obtain estimates of the peak systolic and end diastolic flow velocities and resistive index ((syst-diast)/syst). Vessels were detected in 93% of the untreated tumors and in 63% of the treated tumors (p<0.001, X2), and the median number of vascular regions found was higher among untreated tumors (3 vs 1, p=0.001, Wilcoxon Rank Sum). The effect of treatment status on the detection of tumor vessels was significant (p=0.039), controlling for age, sex, largest tumor pretreatment diameter, and tumor height at CDI in a logistic regression model. Mean resistive index was lower in the untreated tumors (0.53 vs 0.58, p=0.0050), controlling for tumor height and other covariates in an analysis of variance. On examination with CDI, irradiated tumors had fewer detectable vascular regions and greater resistance to flow than untreated tumors, a pattern consistent with known radiation effects.

  6. Denoising of arterial and venous Doppler signals using discrete wavelet transform: effect on clinical parameters.

    PubMed

    Tokmakçi, Mahmut; Erdoğan, Nuri

    2009-05-01

    In this paper, the effects of a wavelet transform based denoising strategy on clinical Doppler parameters are analyzed. The study scheme included: (a) Acquisition of arterial and venous Doppler signals by sampling the audio output of an ultrasound scanner from 20 healthy volunteers, (b) Noise reduction via decomposition of the signals through discrete wavelet transform, (c) Spectral analysis of noisy and noise-free signals with short time Fourier transform, (d) Curve fitting to spectrograms, (e) Calculation of clinical Doppler parameters, (f) Statistical comparison of parameters obtained from noisy and noise-free signals. The decomposition level was selected as the highest level at which the maximum power spectral density and its corresponding frequency were preserved. In all subjects, noise-free spectrograms had smoother trace with less ripples. In both arterial and venous spectrograms, denoising resulted in a significant decrease in the maximum (systolic) and mean frequency, with no statistical difference in the minimum (diastolic) frequency. In arterial signals, this leads to a significant decrease in the calculated parameters such as Systolic/Diastolic Velocity Ratio, Resistivity Index, Pulsatility Index and Acceleration Time. Acceleration Index did not change significantly. Despite a successful denoising, the effects of wavelet decomposition on high frequency components in the Doppler signal should be challenged by comparison with reference data, or, through clinical investigations.

  7. Color Doppler analysis of female reproductive vasculature in Behçet's disease.

    PubMed

    Tezcan, M E; Temizkan, O; Ozderya, A; Melikoglu, M; Aydin, K; Sargin, M; Temizkan, S

    2015-12-30

    Behçet's disease (BD) may affect female reproductive vasculature. We aimed to evaluate Doppler sonographic characteristics of female reproductive vasculature and also ovarian volume, endometrial thickness (EMT) and antral follicle count of BD patients in comparison with a healthy control group. Seventeen premenopausal women aged between 18-45 years with BD, and a control group of 31 age- and body mass index-matched healthy women was included in the study. Uterine, spiral and intraovarian artery blood flow were examined by Doppler sonography in the late follicular phase. Resistance index, pulsatility index and systolic/diastolic ratio were recorded together with ovarian volume, EMT and antral follicle count. In particular this is a pilot study including the evaluation of the spiral and uterine arteries in BD. Doppler sonographic parameters, ovarian volume, EMT and antral follicle count of BD patients and healthy controls were not found to be statistically different. As a result of our analysis, we found similar Doppler sonographic features of both BD patients and the control group. Further studies conducted on a larger sample population with more aggressive BD symptoms may reveal the actual effect of BD on the female reproductive system.

  8. Embedded Doppler system for industrial in-line rheometry.

    PubMed

    Ricci, Stefano; Liard, Maxime; Birkhofer, Beat; Lootens, Didier; Bruhwiler, Armin; Tortoli, Piero

    2012-07-01

    Rheological fluid behavior characterization is crucial for the industrial production of cosmetics, food, pharmaceutics, adhesive, sealants, etc. For example, the measurement of specific rheological features at every step of the production chain is critical for product quality control. Such measurements are often limited to laboratory tests on product specimens because of technical difficulties. In this work, we present an embedded system suitable for in-line rheometric evaluation of highly filled polyurethane-based adhesives. This system includes an ultrasound front-end and a digital signal processing section integrated in a low-cost field-programmable gate array. The system measures the real-time velocity profile developed in the pipe by the fluid, employing a Doppler multigate technique. The high-resolution velocity profile, combined with a pressure drop measurement, allows an accurate evaluation of the flow consistency index, K, and the flow behavior index, n, of the interrogated fluid.

  9. Progress in Doppler picture velocimetry (DPV)

    NASA Astrophysics Data System (ADS)

    Seiler, F.; George, A.; Srulijes, J.; Havermann, M.

    2008-03-01

    The special wide-field Michelson interferometer designed at ISL transforms the Doppler frequency shift of light scattered by tracer particles crossing a light sheet into a shift of luminous intensity at the output of the Michelson interferometer, yielding information about the particle velocity. To overcome former disadvantages, the optical set-up as well as the Doppler picture-processing algorithm were further improved. The present status of Doppler picture velocimetry (DPV) is explained by means of measurements carried out at Mach 6 in the ISL shock tunnel STA. The vertical velocity distribution around several bodies, such as a wedge, a sphere and a cylinder was visualized and measured.

  10. Automatic indexing

    SciTech Connect

    Harman, D.

    1992-09-01

    Automatic indexing has been a critical technology as more full-text data becomes available online. The paper discusses issues for automatic indexing of different types of full-text and also presents a survey of much of the current research into new techniques for automatic indexing.

  11. Author Indexing.

    ERIC Educational Resources Information Center

    Diodato, Virgil P.

    1981-01-01

    Discusses the effectiveness of using author-supplied indexing to increase subject control in information retrieval, and describes a study which compared author indexing for articles published in "American Mathematical Society" journals to indexing of the same articles by an editor of "Mathematical Reviews." Nine references are…

  12. Doppler backscatter properties of a blood-mimicking fluid for Doppler performance assessment.

    PubMed

    Ramnarine, K V; Hoskins, P R; Routh, H F; Davidson, F

    1999-01-01

    The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its suitability for use in a Doppler flow test object. Measurements were performed using a flow rig with C-flex tubing and BMF flow produced by a roller pump or a gear pump. A SciMed Doppler system was used to measure the backscattered Doppler power with a root-mean-square power meter connected to the audio output. Studies investigated the dependence of the backscattered Doppler power of the BMF with: circulation time; batch and operator preparations; storage; sieve size; flow speed; and pump type. A comparison was made with human red blood cells resuspended in saline. The backscatter properties are stable and within International Electrotechnical Commission requirements. The BMF is suitable for use in a test object for Doppler performance assessment.

  13. Three-dimensional ultrasound power Doppler assessment of the cervix: comparison between nulliparas and multiparas.

    PubMed

    Basgul, Alin; Kavak, Zehra Nese; Bakirci, Nadi; Gokaslan, Husnu

    2007-01-01

    To assess the sonographic cervical characteristics between nulliparous and multiparous women. Transvaginal three-dimensional ultrasound and power Doppler using the virtual organ computer-aided analysis (VOCAL) program were performed on 71 nulliparas and 59 multiparas at a mean gestational age of 25.3+/-7.9 weeks. We compared the cervical volume and power Doppler vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) between nulliparas and multiparas. The mean cervical volume and mean VI, VFI, FI measurements were not significantly different between multiparas and nulliparas. Our observations suggest that the morphological changes in the cervix of parous women are merely configurational without a change in cervical mass and vascularization. These configurational changes might result from the inevitable cervical stretching during labor and represent a healing process that does not involve a subsequent change in mass or vascularity.

  14. Relative blood flow changes measured using calibrated frequency-weighted Doppler power at different hematocrit levels.

    PubMed

    Wallace, Sean; Logallo, Nicola; Faiz, Kashif W; Lund, Christian; Brucher, Rainer; Russell, David

    2014-04-01

    In theory, the power of a trans-cranial Doppler signal may be used to measure changes in blood flow and vessel diameter in addition to velocity. In this study, a flow index (FI) of relative changes in blood flow was derived from frequency-weighted Doppler power signals. The FI, plotted against velocity, was calibrated to the zero intercept with absent flow to reduce the effects of non-uniform vessel insonation. An area index was also calculated. FIs were compared with actual flow in four silicone tubes of different diameter at increasing flow rates and increasing hematocrit (Hct) in a closed-loop phantom model. FI values were strongly correlated with actual flow, at constant Hct, but varied substantially with changes in Hct. Percentage changes in area indexes, relative to the 4-mm tube, were strongly correlated with tube cross-sectional area. The implications of these results for in vivo use are discussed.

  15. Assessment of myocardial function in preterm infants with patent ductus arteriosus using tissue Doppler imaging.

    PubMed

    Parikh, Ravikumar; Negrine, Robert J S; Chikermane, Ashish; Rasiah, Shree Vishna; Ewer, Andrew K

    2015-01-01

    To assess myocardial function in preterm infants with different degrees of ductal patency in the first week of life using tissue Doppler imaging. Infants <30 weeks of gestation underwent echocardiography on day 3. A total of 72 infants were recruited into the study and categorised into three groups (i) haemodyamically significant ductus arteriosus, (ii) patent ductus arteriosus and (iii) no patent ductus arteriosus. Those with haemodynamically significant ductus arteriosus were treated with indometacin and echocardiography was repeated after 48-72 hours following treatment. Peak systolic and diastolic myocardial velocities were obtained using tissue Doppler imaging, and myocardial performance index was calculated. Initial myocardial velocities were significantly lower and myocardial performance index significantly higher in the haemodynamically significant ductus arteriosus group compared with other groups. For the haemodynamically significant ductus arteriosus group, post-treatment myocardial velocities were higher and myocardial performance index lower than pre-treatment. Preterm infants with haemodynamically significant ductus arteriosus had lower myocardial velocities and higher myocardial performance index, suggesting relative systolic and diastolic myocardial dysfunction. Babies whose patent ductus arteriosus remained open despite indometacin had lower pre-treatment myocardial velocities and higher myocardial performance index than those babies whose patent ductus arteriosus closed, suggesting worse myocardial function in this group. Measurement of myocardial function using tissue Doppler imaging in preterm infants is feasible and may prove to be helpful in the management of babies with patent ductus arteriosus.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  17. Phase control of probe response in a Doppler-broadened N-type four-level system

    SciTech Connect

    Fan Xijun; Liu Zhongbo; Liang Ying; Jia Kening; Tong Dianmin

    2011-04-15

    In this paper, we investigate theoretically the effect of the relative phase ({phi}) between the probe and driving fields on gain (absorption) and dispersion of the probe field in a Doppler-broadened N-type four-level system with spontaneously generated coherence from different respects. It is shown that gain (absorption) and dispersion are very sensitive to variations in the relative phase, and changing the Doppler width also has an obvious effect on the phase-dependent gain (absorption) and dispersion. When the probe and driving fields have the same propagation directions (copropagating), for the same Doppler width, the dispersion curve with {phi}={alpha} is the same as the gain (absorption) curve with {phi}={alpha}+{pi}/2; however, when the probe and driving fields have opposite propagation directions (counterpropagating), the dispersion curve and gain (absorption) curve are different and the difference becomes more considerable with an increase in Doppler width. In the co- and counterpropagating cases, gain (absorption) and dispersion always vary periodically with varying {phi}, and the period is 2{pi}. By adjusting the value of {phi}, the largest gain (absorption) and dispersion can be obtained, and a large index of refraction without absorption can be realized. Generally speaking, gain decreases with an increase in Doppler width, but by adjusting value of {phi}, at some special values of Doppler width, a larger gain than that without Doppler broadening can be obtained. Our study also shows that gain in the copropagating case is much larger than that in the counterpropagating case.

  18. Can Doppler or contrast-enhanced ultrasound analysis add diagnostically important information about the nature of breast lesions?

    PubMed Central

    Stanzani, Daniela; Chala, Luciano F.; de Barros, Nestor; Cerri, Giovanni G.; Chammas, Maria Cristina

    2014-01-01

    OBJECTIVES: Despite evidence suggesting that Doppler ultrasonography can help to differentiate between benign and malignant breast lesions, it is rarely applied in clinical practice. The aim of this study was to determine whether certain vascular features of breast masses observed by duplex Doppler and color Doppler ultrasonography (before and/or after microbubble contrast injection) add information to the gray-scale analysis and support the Breast Imaging-Reporting and Data System (BI-RADS) classification. METHODS: Seventy solid lesions were prospectively evaluated with gray-scale ultrasonography, color Doppler ultrasonography, and contrast-enhanced ultrasonography. The morphological analysis and lesion vascularity were correlated with the histological results. RESULTS: Percutaneous core biopsies revealed that 25/70 (17.5%) lesions were malignant, while 45 were benign. Hypervascular lesions with tortuous and central vessels, a resistive index (RI)≥0.73 before contrast injection, and an RI≥0.75 after contrast injection were significantly predictive of malignancy (p<0.001). CONCLUSION: The combination of gray-scale ultrasonography data with unenhanced or enhanced duplex Doppler and color Doppler US data can provide diagnostically useful information. These techniques can be easily implemented because Doppler devices are already present in most health centers. PMID:24519198

  19. Tissue perfusion measurements: multiple-exposure laser speckle analysis generates laser Doppler-like spectra.

    PubMed

    Thompson, Oliver B; Andrews, Michael K

    2010-01-01

    Variations in skin perfusion are easily detected by laser speckle contrast maps, but a robust interpretation of the information has been lacking. We show that multiple-exposure laser speckle methods produce the same spectral information as laser Doppler methods when applied to targets with embedded moving scatterers. This enables laser speckle measurements to be interpreted more quantitatively. We do this by using computer simulation of speckle data, and by experimental measurements on Brownian motion and skin perfusion using a laser Doppler system and a multiple-exposure laser speckle system. The power spectral density measurements of the light fluctuations derived using both techniques are exactly equivalent. Dermal perfusion can therefore be measured by laser Doppler or laser speckle contrast methods. In particular, multiexposure laser speckle can be rapidly processed to generate a full-field map of the perfusion index proportional to the concentration and mean velocity of red blood cells.

  20. Analysis of a Four-Station Doppler Tracking Method Using a Simple CW Beacon

    NASA Technical Reports Server (NTRS)

    Fricke, Clifford L.; Watkins, Carl W. L.

    1961-01-01

    A Doppler tracking method is presented in which a very small, simple CW beacon transmitter is used with four Doppler receiving stations to obtain the position and velocity of a space research vehicle. The exact transmitter frequency need not be known, but an initial position is required, and Doppler frequencies must be measured with extreme accuracy. The errors in the system are analyzed and general formulas are derived for position and velocity errors. The proper location of receiving stations is discussed, a rule for avoiding infinite errors is given, and error charts for ideal station configurations are presented. The effect of the index of refraction is also investigated. The system is capable of determining transmitter position within 1,000 feet at a range of 200 miles.

  1. A study of the spectral broadening of simulated Doppler signals using FFT and AR modelling.

    PubMed

    Keeton, P I; Schlindwein, F S; Evans, D H

    1997-01-01

    Doppler ultrasound is used clinically to detect stenosis in the carotid artery. The presence of stenosis may be identified by disturbed flow patterns distal to the stenosis that cause spectral broadening in the spectrum of the Doppler signal around peak systole. This paper investigates the behaviour of the spectral broadening index (SBI) derived from wide-band spectra obtained using autoregressive modelling (AR), compared with the SBI based on the fast-Fourier transform (FFT) spectra. Simulated Doppler signals were created using white noise and shaped filters to analyse spectra typically found around the systolic peak and to assess the magnitude and variance of AR and FFT-SBI for a range of signal-to-noise ratios. The results of the analysis show a strong correlation between the indices calculated using the FFT and AR algorithms. Despite the qualitative improvement of the AR spectra over the FFT, the estimation of SBI for short data frames is not significantly improved using AR.

  2. Intensity changes in the Doppler effect

    PubMed Central

    Johnson, Montgomery H.; Teller, Edward

    1982-01-01

    When a source moves in any direction, the source strength and the frequencies are altered by the Doppler effect. It is shown that the source strength divided by the cube of the frequency is a Lorentz invariant. PMID:16593162

  3. Teaching the Doppler effect in astrophysics

    NASA Astrophysics Data System (ADS)

    Hughes, Stephen W.; Cowley, Michael

    2017-03-01

    The Doppler effect is a shift in the frequency of waves emitted from an object moving relative to the observer. By observing and analysing the Doppler shift in electromagnetic waves from astronomical objects, astronomers gain greater insight into the structure and operation of our Universe. In this paper, a simple technique is described for teaching the basics of the Doppler effect to undergraduate astrophysics students using acoustic waves. An advantage of the technique is that it produces a visual representation of the acoustic Doppler shift. The equipment comprises a 40 kHz acoustic transmitter and a microphone. The sound is bounced off a computer fan and the signal collected by a DrDAQ ADC and processed by a spectrum analyser. Widening of the spectrum is observed as the fan power supply potential is increased from 4 to 12 V.

  4. Laser Doppler Measurement of Atmopsheric Wind Velocity

    NASA Technical Reports Server (NTRS)

    Schwiesow, R. L.; Abshire, N. L.; Derr, V. E.

    1973-01-01

    Our presentation consists of two parts: (1) a summary review of laser Doppler principles and applications, and (2) operational design and preliminary laboratory tests of a CO2 laser system for NOAA applications.

  5. Epiploic appendagitis: color Doppler sonographic findings.

    PubMed

    Danse, E M; Van Beers, B E; Baudrez, V; Pauls, C; Baudrez, Y; Kartheuser, A; Thys, F; Pringot, J

    2001-01-01

    The aim of this study was to analyze the color Doppler sonographic findings in primary epiploic appendagitis. Color Doppler sonographic findings of ten patients with primary epiploic appendagitis were reviewed. The following sonographic features were analyzed: identification of a mass adjacent to the colonic wall; identification of spotty color areas with arterial flow in this mass and detection of abnormalities of the colonic wall adjacent to the infiltrated fatty tissue. A well-delineated hyperechoic mass adjacent to the colonic wall was detected in each patient with sonography. No colonic wall abnormalities were observed nor color Doppler signal in and around the hyperechoic area. Absence of flow at color Doppler sonography is an additional feature of epiploic appendagitis.

  6. Student Microwave Experiments Involving the Doppler Effect.

    ERIC Educational Resources Information Center

    Weber, F. Neff; And Others

    1980-01-01

    Described is the use of the Doppler Effect with microwaves in the measurement of the acceleration due to gravity of falling objects. The experiments described add to the repertoire of quantitative student microwave experiments. (Author/DS)

  7. Student Microwave Experiments Involving the Doppler Effect.

    ERIC Educational Resources Information Center

    Weber, F. Neff; And Others

    1980-01-01

    Described is the use of the Doppler Effect with microwaves in the measurement of the acceleration due to gravity of falling objects. The experiments described add to the repertoire of quantitative student microwave experiments. (Author/DS)

  8. Generalized Doppler Formula in a Nonstatic Universe

    ERIC Educational Resources Information Center

    Gross, Peter G.

    1977-01-01

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

  9. High range resolution micro-Doppler analysis

    NASA Astrophysics Data System (ADS)

    Cammenga, Zachary A.; Smith, Graeme E.; Baker, Christopher J.

    2015-05-01

    This paper addresses use of the micro-Doppler effect and the use of high range-resolution profiles to observe complex targets in complex target scenes. The combination of micro-Doppler and high range-resolution provides the ability to separate the motion of complex targets from one another. This ability leads to the differentiation of targets based on their micro-Doppler signatures. Without the high-range resolution, this would not be possible because the individual signatures would not be separable. This paper also addresses the use of the micro-Doppler information and high range-resolution profiles to generate an approximation of the scattering properties of a complex target. This approximation gives insight into the structure of the complex target and, critically, is created without using a pre-determined target model.

  10. Evaluation of a pulsed ultrasonic Doppler flowmeter

    NASA Technical Reports Server (NTRS)

    Wells, M. K.

    1973-01-01

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

  11. Doppler vortography: a color Doppler approach for quantification of the intraventricular blood flow vortices

    PubMed Central

    Mehregan, Forough; Tournoux, François; Muth, Stéphan; Pibarot, Philippe; Rieu, Régis; Cloutier, Guy; Garcia, Damien

    2013-01-01

    We propose a new approach for quantification of intracardiac vorticity – Doppler vortography – based on conventional color Doppler images. Doppler vortography relies on the centrosymmetric properties of the vortices. Such properties induce particular symmetries in the Doppler flow data which can be exploited to describe the vortices quantitatively. For this purpose, a kernel filter was developed to derive a parameter –the blood vortex signature (BVS) – that allows detecting the main intracardiac vortices and estimating their core vorticities. The reliability of Doppler vortography was assessed in mock Doppler fields issued from simulations and in vitro data. Doppler vortography was also tested in patients and compared with vector flow mapping by echocardiography. Strong correlations were obtained between the Doppler vortography-derived and the ground-truth vorticities (in silico: r2 = 0.98, in vitro: r2 = 0.86, in vivo: r2 = 0.89). Our results demonstrated that Doppler vortography is a potentially promising echocardiographic tool for quantification of vortex flow in the left ventricle. PMID:24210865

  12. [Pulsed echo-Doppler evaluation of regurgitant fraction in mitral valve insufficiency].

    PubMed

    Tribouilloy, C; Slama, M A; Kugener, H; Dufossé, H; Rey, J L; Lesbre, J P

    1991-09-01

    The aim of this study was to evaluate the validity of Doppler echocardiographic evaluation of the regurgitant fraction in pure mitral insufficiency. The Doppler echocardiographic measurement of systemic flow was made at the level of the aortic ring, and the mitral flow by the method of integration of instantaneous flow proposed by Touche. In a preliminary study, we demonstrated a close correlation between forward aortic and mitral flow in 20 normal subjects (r = 0.94; SD = 0.31 l/mn; y = 0.98 x -0.004). We then studied a group of 38 patients with pure isolated mitral regurgitation. Five patients were excluded because of the poor quality of the echocardiographic documents. The hemodynamic regurgitant fraction was determined by measuring pulmonary flow by thermodilution and the left ventricular outflow by digitised angiography. The average Doppler and hemodynamic regurgitant fractions were 46.6 +/- 18% and 42 +/- 17% respectively. There was a close correlation between the Doppler and hemodynamic values (r = 0.91; SD = 7.8%; y = 0.97 x + 5.7). The correlations were also good between Doppler regurgitant fraction and the four angiographic grades of regurgitation (r = 0.88). A statistically significant difference was observed between the Doppler regurgitant fractions of Grades I and II and of Grades III and IV (p less than 0.001). In addition, the ratio of mitral VTI/aortic VTI gave a useful index of regurgitation in pure mitral insufficiency. When the ratio was greater than 1.3 the regurgitant fraction was over 40% with a sensitivity of 79% and a specificity of 86%. Finally, this study shows that pure, isolated mitral regurgitation can be evaluated by Doppler echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Pulsed Doppler lidar airborne scanner

    NASA Technical Reports Server (NTRS)

    Dimarzio, C. A.; Mcvicker, D. B.; Morrow, C. E.; Negus, C. C.

    1985-01-01

    This report covers the work accomplished during the reporting period on Pulsed Doppler Lidar Airborne Scanner and describes plans for the next reporting period. The objectives during the current phase of the contract are divided into four phases. Phase 1 includes ground testing of the system and analysis of data from the 1981 Severe Storms Test Flights. Phase 2 consists of preflight preparation and planning for the 1983 flight series. The flight test itself will be performed during Phase 3, and Phase 4 consists of post-flight analysis and operation of the system after that flight test. The range profile from five samples taken during Flight 10, around 1700 Z is given. The lowest curve is taken from data collected upwind of Mt. Shasta at about 10,000 feet of altitude, in a clear atmosphere, where no signals were observed. It thus is a good representation of the noise level as a function of range. The next curve was taken downwind of the mountain, and shows evidence of atmospheric returns. There is some question as to whether the data are valid at all ranges, or some ranges are contaminated by the others.

  14. The use of unenhanced Doppler sonography in the evaluation of solid breast lesions.

    PubMed

    del Cura, Jose L; Elizagaray, Elena; Zabala, Rosa; Legórburu, Ana; Grande, Domingo

    2005-06-01

    The objectives of our study were to investigate differences in Doppler sonography features between benign and malignant breast lesions and between malignant lesions with different prognostic factors and to propose diagnostic criteria for Doppler sonography of breast lesions. We performed power and duplex Doppler sonography examinations in 826 breast lesions scheduled for sonographically guided core needle biopsy. Lesion vascularity, pulsatility index (PI), and resistive index (RI) of the vessels detected were analyzed and correlated with histologic results. Color flow was more frequently seen in malignant (237/348 lesions, 68%) than in benign (171/478, 36%) lesions (p < 0.001). However, sensitivity, specificity, and positive and negative predictive values for this sign were low (68%, 64%, 58%, and 73%, respectively). The RI and PI values were significantly higher (p < 0.001) in cancers. Although an overlap in these values between benign and malignant lesions was observed, all but one nodule with an RI of greater than 0.99 (those with null or inverted diastolic flow) or a PI of greater than 4 were malignant. No significant relationship was found between PI, RI, or flow visualization on power Doppler sonography and tumor grade or lymph node involvement in cancers. Flow visualization on power Doppler sonography indicates a higher possibility of malignancy but is not useful as the main sign for malignancy. However, any lesion with a vessel that has an RI value greater than 0.99 or a PI value greater than 4 within it must be considered as probably malignant regardless of any other sonography sign present. Doppler findings are not useful to predict tumor grade or lymph node involvement.

  15. Doppler micro sense and avoid radar

    NASA Astrophysics Data System (ADS)

    Gorwara, Ashok; Molchanov, Pavlo; Asmolova, Olga

    2015-10-01

    There is a need for small Sense and Avoid (SAA) systems for small and micro Unmanned Aerial Systems (UAS) to avoid collisions with obstacles and other aircraft. The proposed SAA systems will give drones the ability to "see" close up and give them the agility to maneuver through tight areas. Doppler radar is proposed for use in this sense and avoid system because in contrast to optical or infrared (IR) systems Doppler can work in more harsh conditions such as at dusk, and in rain and snow. And in contrast to ultrasound based systems, Doppler can better sense small sized obstacles such as wires and it can provide a sensing range from a few inches to several miles. An SAA systems comprised of Doppler radar modules and an array of directional antennas that are distributed around the perimeter of the drone can cover the entire sky. These modules are designed so that they can provide the direction to the obstacle and simultaneously generate an alarm signal if the obstacle enters within the SAA system's adjustable "Protection Border". The alarm signal alerts the drone's autopilot to automatically initiate an avoidance maneuver. A series of Doppler radar modules with different ranges, angles of view and transmitting power have been designed for drones of different sizes and applications. The proposed Doppler radar micro SAA system has simple circuitry, works from a 5 volt source and has low power consumption. It is light weight, inexpensive and it can be used for a variety of small unmanned aircraft.

  16. [Cerebral Doppler ultrasonography in newborn infants].

    PubMed

    Luciano, R; Velardi, F

    1995-01-01

    Following the first study of Bada et al. (1979), Doppler assessment of cerebral blood flow has increasingly been used in newborn infants, matching the technical progress in the available equipment. The experience gathered in recent years has confirmed that Doppler US is a reliable and reproducible examination while precising the limitations and the methodology to be followed in order to prevent gross errors of assessment and interpretation. The interest this procedure has arisen, among other things, stems from being noninvasive and feasible at the patient's bed. These features enable its repeated use in newborn infants in poor clinical condition. The diagnostic and prognostic role of Doppler velocimetry has been shown in a number of neonatal diseases and the cerebral hemodynamics has been assessed in physiologic conditions as well as after drug administration. The most common equipment used in newborn infants is at present Duplex Doppler consisting of a pulsed Doppler combined with bidimensional scanner, which, with visualization of study arteries, enables precise positioning of sample volume and correction of the ultrasonic angle of incidence with respect to the direction of blood flow in the examined vessel. In this report, after a survey of the techniques and modalities of cerebral Doppler examination in newborns, a review of the present state of the art, in neonatal cerebral as well as extracranial disease, is presented.

  17. Doppler-corrected differential detection system

    NASA Technical Reports Server (NTRS)

    Simon, Marvin K. (Inventor); Divsalar, Dariush (Inventor)

    1991-01-01

    Doppler in a communication system operating with a multiple differential phase-shift-keyed format (MDPSK) creates an adverse phase shift in an incoming signal. An open loop frequency estimation is derived from a Doppler-contaminated incoming signal. Based upon the recognition that, whereas the change in phase of the received signal over a full symbol contains both the differentially encoded data and the Doppler induced phase shift, the same change in phase over half a symbol (within a given symbol interval) contains only the Doppler induced phase shift, and the Doppler effect can be estimated and removed from the incoming signal. Doppler correction occurs prior to the receiver's final output of decoded data. A multiphase system can operate with two samplings per symbol interval at no penalty in signal-to-noise ratio provided that an ideal low pass pre-detection filter is employed, and two samples, at 1/4 and 3/4 of the symbol interval T sub s, are taken and summed together prior to incoming signal data detection.

  18. The short-term effect of nifedipine tocolysis on placental, fetal cerebral and atrioventricular Doppler waveforms.

    PubMed

    Guclu, S; Saygili, U; Dogan, E; Demir, N; Baschat, A A

    2004-12-01

    To evaluate the effect of nifedipine on placental and fetal middle cerebral and atrioventricular Doppler waveforms. Doppler waveforms of uterine (UtA), umbilical (UA) and middle cerebral (MCA) arteries and both atrioventricular valves were measured from 21 pregnant women/fetuses prior to and during nifedipine therapy for preterm labor. Maternal and fetal heart rates (FHR), maternal systolic and diastolic blood pressure, the Doppler pulsatility index and systolic/diastolic ratio of the UtA, UA and MCA were measured. The total time velocity integrals (TVI) of tricuspid and mitral valves and their E-wave/A-wave (E/A) TVI ratios were measured. Wilcoxon signed pairs test was used to compare the differences in Doppler parameters before and at 3 h after nifedipine loading up to a maximum dose of 40 mg. Fetal arterial and UtA Doppler parameters were not different before and after nifedipine therapy. Blood flow across the atrioventricular valves and the TVI were equally unaffected by nifedipine. The TVI x FHR product was also unchanged following nifedipine therapy. In women with otherwise uncomplicated pregnancies, nifedipine loading and tocolysis are generally well tolerated by the mother. Placental and fetal cerebral arterial blood flow, fetal systolic and diastolic cardiac function and downstream distribution of fetal cardiac output are unaffected by nifedipine loading. These results apply to women with unchanged vital parameters. Further studies are necessary to show long-term effects of nifedipine therapy and may help to refine choice of tocolytic agents.

  19. Echocardiographic evaluation of external iliac artery Doppler waveform in patients with coronary artery disease.

    PubMed

    Styczynski, Grzegorz; Szmigielski, Cezary; Kaczynska, Anna; Kuch-Wocial, Agnieszka

    2014-04-01

    Visual interpretation of the Doppler waveform in the common femoral or distal external iliac artery (EIA) was reported to be useful in screening for proximal peripheral artery occlusive disease (PAOD) in patients with lower limb ischemia. Commonly patients with coronary artery disease (CAD) referred for echocardiography have coexistent arterial pathology. Therefore, we decided to study whether echocardiographic evaluation of the distal EIA flow can be useful for detection of PAOD in patients with CAD. We studied 150 consecutive patients (pts) with CAD referred for echocardiography. At the end of an echocardiographic examination, evaluation of the flow in the distal EIA with an echocardiographic probe was performed. The Doppler waveform was classified as normal-with early diastolic flow reversal or abnormal-without early diastolic flow reversal. Echocardiographic findings were compared in a blinded fashion with the results of the ankle brachial index measurements (ABI). Based on the ABI ≤ 0.9, peripheral artery disease was diagnosed in 54 pts (36%) and abnormal external iliac Doppler waveform was found in 27 pts (18%). Sensitivity of abnormal external iliac Doppler waveform in predicting PAOD was 48%, specificity 99%, positive predictive value (PPV) 96%, and negative predictive value 77%. Peripheral arterial occlusive disease is common in patients with CAD referred for echocardiographic study. Echocardiographic assessment of distal EIA Doppler waveform has low sensitivity, but high specificity and high PPV in the diagnosis of peripheral arterial occlusive disease.

  20. Early postoperative spectral Doppler parameters of renal transplants: the effect of donor and recipient factors.

    PubMed

    Wang, H-K; Chiou, S-Y; Lai, Y-C; Cheng, H-Y; Lin, N-C; Loong, C-C; Chiou, H-J; Chou, Y-H; Chang, C-Y

    2012-01-01

    The objective of this study was to explore the donor and recipient factors related to the spectral Doppler parameters of the transplant kidney in the early posttransplantation period. This retrospective study included 76 patients who underwent renal transplantation assessed using Doppler ultrasonography (US) on the first postoperative day. We compared spectral Doppler parameters (peak systolic velocity [PSV] and resistive index [RI]) of the segmental artery of the transplant kidney according to the type of renal transplant, level of serum creatinine (SCr) of donor prior to organ donation, and donor/recipient age. RI was significantly higher in deceased-donor kidney transplantation (DDKT) as compared with living-donor kidney transplantation (LDKT; 0.73 ± 0.10 vs 0.66 ± 0.11; P = .007). In the DDKT recipients, multivariate analysis showed donor SCr was the only factor affecting PSV (P = .023), whereas recipient age was the only factor affecting RI (P = .035). In the LDKT recipients, multivariate analysis showed recipient age was the only factor affecting both PSV (P = .009) and RI (P = .018). Spectral Doppler parameters in the early posttransplantation period are related to the type of renal transplant, donor renal function, and recipient age. These factors should be taken into consideration when interpreting the results of spectral Doppler US. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Assessment of cardiac functions using tissue Doppler imaging in children with familial Mediterranean fever.

    PubMed

    Ozdemir, Osman; Agras, Pinar Isik; Aydin, Yusuf; Abaci, Ayhan; Hizli, Samil; Akkus, Halil Ibrahim; Fidan, Cihan

    2012-04-01

    Familial Mediterranean fever may carry a potential for cardiovascular disorders because of sustained inflammation during its course; however, there has been a limited number of studies investigating the cardiac functions in children. The aim of this study was to assess both ventricular diastolic functions using conventional echocardiography and tissue Doppler imaging in children with familial Mediterranean fever. The study population included 25 patients with familial Mediterranean fever - mean age was 11.8 plus or minus 5.30 years - and 23 healthy patients as controls - mean age was 9.88 plus or minus 3.69 years. Both ventricular functions were measured using echocardiography comprising standard M-mode and conventional Doppler and tissue Doppler imaging during an attack-free period. The conventional echocardiographic parameters with myocardial performance index were in normal ranges and similar in patients with familial Mediterranean fever and controls, with a p-value more than 0.05. However, right ventricular diastolic dysfunction was observed in patients with familial Mediterranean fever documented by tissue Doppler imaging, with a p-value less than 0.05 for E't and A't wave ratio. Using tissue Doppler imaging, we have demonstrated that although left ventricular functions were comparable in the patients and healthy children, right ventricular diastolic function indices were impaired in patients with familial Mediterranean fever during childhood. Impaired right ventricular diastolic function may be an early manifestation of cardiac involvement in children with familial Mediterranean fever.

  2. Index interferometer

    NASA Astrophysics Data System (ADS)

    Ludman, Jacques E.; Riccobono, Juanita R.

    1993-01-01

    The Index Interferometer is a novel instrument being developed by Northeast Photosciences. The instrument is a breakthrough in the high-accuracy measurement of the index of refraction, the dispersion, and the index profile of materials. The instrument accurately measures the index of refraction of materials to one or two more significant figures than previous instruments. Material slices polished moderately flat are sufficient, without any requirement for special or complicated material shapes, such as prisms. The index profile at any chosen wavelength can be measured using a simple color filter. No special laser sources or carefully collimated parallel beams are required. The index profile over an entire sample can be directly obtained at any desired wavelength. This instrument is remarkable in that it greatly increases the accuracy of measurement, eliminates the need for high-quality, extremely narrow sources and for fabrication of special-geometry samples, and adds additional features, such as index profile measurements. The technique compares the fringe pattern from the top surface with that from a reference mirror to determine the thickness. Then, with the aid of a filtered white light source, the interference pattern from the back surface is compared with that from the front to yield the optical thickness of the sample. The combination of the two measurements gives the index. The back surface fringe pattern itself gives the index profile.

  3. Uterine artery Doppler flow velocimetry parameters for predicting gestational trophoblastic neoplasia after complete hydatidiform mole, a prospective cohort study

    PubMed Central

    Asmar, Flavia Tarabini Castellani; Braga-Neto, Antonio Rodrigues; de Rezende-Filho, Jorge; Villas-Boas, Juliana Marques Simões; Charry, Rafael Cortés; Maesta, Izildinha

    2017-01-01

    OBJECTIVES: Doppler ultrasonography can be used to assess neoangiogenesis, a characteristic feature of postmolar gestational trophoblastic neoplasia. However, there is limited information on whether uterine artery Doppler flow velocimetry parameters can predict gestational trophoblastic neoplasia following a complete hydatidiform mole. The purpose of this study was as follows: 1) to compare uterine blood flow before and after complete mole evacuation between women who developed postmolar gestational trophoblastic neoplasia and those who achieved spontaneous remission, 2) to assess the usefulness of uterine Doppler parameters as predictors of postmolar gestational trophoblastic neoplasia and to determine the best parameters and cutoff values for predicting postmolar gestational trophoblastic neoplasia. METHODS: This prospective cohort study included 246 patients with a complete mole who were treated at three different trophoblastic diseases centers between 2013 and 2014. The pulsatility index, resistivity index, and systolic/diastolic ratio were measured by Doppler flow velocimetry before and 4-6 weeks after molar evacuation. Statistical analysis was performed using Wilcoxon’s test, logistic regression, and ROC analysis. RESULTS: No differences in pre- and post-evacuation Doppler measurements were observed in patients who developed postmolar gestational trophoblastic neoplasia. In those with spontaneous remission, the pulsatility index and systolic/diastolic ratio were increased after evacuation. The pre- and post-evacuation pulsatility indices were significantly lower in patients with gestational trophoblastic neoplasia (odds ratio of 13.9-30.5). A pre-evacuation pulsatility index ≤1.38 (77% sensitivity and 82% specificity) and post-evacuation pulsatility index ≤1.77 (79% sensitivity and 86% specificity) were significantly predictive of gestational trophoblastic neoplasia. CONCLUSIONS: Uterine Doppler flow velocimetry measurements, particularly pre- and post

  4. Blood flow velocity in monocular retinoblastoma assessed by color doppler

    PubMed Central

    Bonanomi, Maria Teresa B C; Saito, Osmar C; de Lima, Patricia Picciarelli; Bonanomi, Roberta Chizzotti; Chammas, Maria Cristina

    2015-01-01

    OBJECTIVE: To analyze the flow of retrobulbar vessels in retinoblastoma by color Doppler imaging. METHODS: A prospective study of monocular retinoblastoma treated by enucleation between 2010 and 2014. The examination comprised fundoscopy, magnetic resonance imaging, ultrasonography and color Doppler imaging. The peak blood velocities in the central retinal artery and central retinal vein of tumor-containing eyes (tuCRAv and tuCRVv, respectively) were assessed. The velocities were compared with those for normal eyes (nlCRAv and nlCRVv) and correlated with clinical and pathological findings. Tumor dimensions in the pathological sections were compared with those in magnetic resonance imaging and ultrasonography and were correlated with tuCRAv and tuCRVv. In tumor-containing eyes, the resistivity index in the central retinal artery and the pulse index in the central retinal vein were studied in relation to all variables. RESULTS: Eighteen patients were included. Comparisons between tuCRAv and nlCRAv and between tuCRVv and nlCRVv revealed higher velocities in tumor-containing eyes (p<0.001 for both), with a greater effect in the central retinal artery than in the central retinal vein (p=0.024). Magnetic resonance imaging and ultrasonography measurements were as reliable as pathology assessments (p=0.675 and p=0.375, respectively). A positive relationship was found between tuCRAv and the tumor volume (p=0.027). The pulse index in the central retinal vein was lower in male patients (p=0.017) and in eyes with optic nerve invasion (p=0.0088). CONCLUSIONS: TuCRAv and tuCRVv are higher in tumor-containing eyes than in normal eyes. Magnetic resonance imaging and ultrasonography measurements are reliable. The tumor volume is correlated with a higher tuCRAv and a reduced pulse in the central retinal vein is correlated with male sex and optic nerve invasion. PMID:26735219

  5. Effect of laparoscopic ovarian drilling on vascular endothelial growth factor and ovarian stromal blood flow using 3-dimensional power Doppler.

    PubMed

    El Behery, Manal M; Diab, Abdalla E; Mowafy, Hala; Ebrahiem, Moustafa A; Shehata, Amal E

    2011-02-01

    To determine, by using 3-dimensional power Doppler ultrasonography, the effect of laparoscopic ovarian drilling (LOD) on the serum level of vascular endothelial growth factor (VEGF) and ovarian stromal blood flow changes in polycystic ovary syndrome (PCOS). A prospective controlled clinical study was conducted on 26 clomiphene-resistant women with PCOS who were scheduled for LOD and a control group of 22 fertile regularly menstruating women. VEGF and 3 ovarian Doppler indices-vascularization index, flow index, and vascularization flow index-were measured and compared between the 2 groups, and before and after LOD in the PCOS group. Serum VEGF and the Doppler indices of ovarian stromal blood flow were significantly higher in the PCOS group than in the control group. Serum VEGF and the ovarian stromal blood flow Doppler indices were significantly reduced in the PCOS group after LOD. Increased vascularity in PCOS demonstrated by Doppler blood flow measurements might be explained by the high level of VEGF. LOD reduced ovarian vascularization and serum VEGF. Copyright © 2010 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

  6. Retroreflector for photonic Doppler velocimetry

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

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

  7. B-mode and Doppler sonography of the mammary glands in dairy goats for mastitis diagnosis.

    PubMed

    Santos, V J C; Simplício, K; Sanchez, D; Coutinho, L; Teixeira, P; Barros, F; Almeida, V; Rodrigues, L; Bartlewski, P; Oliveira, M; Feliciano, M; Vicente, W

    2015-04-01

    This study aimed to evaluate the sonographic characteristics of the udder and teats and to determine the Doppler indexes of mammary artery in healthy and undergoing subclinical and clinical mastitis goats. Thirty animals among Saanen and Alpine Brown goats were arranged in three groups, healthy goats (HG), goats with subclinical mastitis (SMG) and goats with clinical mastitis (CMG). Using the B-mode, the sonographic characteristics (echotexture and echogenicity) and biometry (diameter and area of the udder cistern, diameter and area of the teat cistern and thickness of the teat wall) were evaluated. Using Doppler ultrasonography, the vascular indexes of the mammary artery were obtained. It was observed hyperechogenicity with solid component in the gland cistern when comparing animals with clinical mastitis and healthy mammary tissue. Regarding the echotexture of the breast tissue, there was heterogeneity in the mammary parenchyma on the three groups, for the milk, it was observed homogeneity for animals on HG and SMG and heterogeneity for animals on CMG. Grey-scale quantitative assessment revealed increase in echogenicity (mean value) for all the structures when comparing the three groups. Biometry did not reveal statistical difference between groups, for none of the evaluated structures. Doppler examination of the mammary artery showed the decrease of end diastolic velocity and raise of pulsatility index between groups. The association of B-mode and Doppler ultrasonography is useful for the evaluation of the udder of dairy goats with mastitis. It is a sensitive and specific method for the study of this disease. Doppler mode was unable to establish reliable criteria for diagnosis of subclinical mastitis. Moreover, the quantification of echogenicity is a useful technique for the evaluation of the milk in animals with mastitis; therefore, it is suggested that it can be used as complementary technique for the diagnosis of mastitis in goats.

  8. [Quantification and monitoring of vascular resistance in the lower limbs by the Doppler method (animal model)

    NASA Technical Reports Server (NTRS)

    Arbeille, P.; Berson, M.; Blondeau, B.; Durand, A.; Bodard, S.; Locatelli, A.; Fox, G. E. (Principal Investigator)

    1995-01-01

    The object of this study was to define and validate a non-invasive method of evaluation and monitoring of vascular resistances in the leg. Blood flow velocity was measured by Doppler ultrasound in an animal model (ewe) with similar blood flow characteristics in the lower limb as man and allowing access to the required invasive measurements for validation of the method (pressure and flow). Vascular resistances distal to the measuring point (femoral, for example) were assessed using the resistance index R = D/S, S being the peak systolic deflection and D that of diastolic reflux of the Doppler spectral analysis of flow in the femoral artery. The values and variations of this resistance index were compared with the vascular resistances calculated from measurements of pressure and flow at the point of Doppler sampling and expressed in mmHg/ml/min. Femoral flow was measured by Doppler ultrasound (Doppler-echo), and mean pressure by an arterial catheter introduced into the abdominal aorta. Compression of the lower limb veins induced a venous return resulting in a reduction of cardiac output and femoral flow. During compression, femoral flow decreased by an average of 29% (p < 0.001) although mean pressure and heart rate did not change significantly. The femoral resistance index (Rf) increased by an average of 37.5% (p < 0.01) and vascular resistances increased by 45.9% (p < 0.01). Injection of 1 mg adrenaline induced peripheral vasoconstriction with an increase in blood pressure and a decrease in heart rate and femoral flow.(ABSTRACT TRUNCATED AT 250 WORDS).

  9. Color Doppler energy prediction of malignancy in adnexal masses using logistic regression models.

    PubMed

    Marret, H; Ecochard, R; Giraudeau, B; Golfier, F; Raudrant, D; Lansac, J

    2002-12-01

    The aim of this study was to assess the usefulness of color Doppler energy in the preoperative diagnosis of ovarian malignancy using multivariate logistic regression analysis. One hundred and thirty adnexal masses were studied with transvaginal B-mode, color energy, and pulsed Doppler ultrasonography before surgery in order to develop a model that could be used to determine malignancy. Each ultrasonographic variable (tumor size, wall thickness, septal structure, echogenicity, papillary projection, density (solid or not)) was included individually or combined together as part of the Sassone ultrasound score. Intratumoral blood flow velocity waveforms were obtained to determine pulsatility index and resistance index and a more subjective parameter, location of tumor vascularity, was also assessed. Menopausal status and serum CA 125 levels were also entered as categorical variables. Sonographic parameters were entered alone, then associated with menopausal status and CA 125 serum levels, and finally with Doppler energy measurements. Our model was then validated in a group of 68 adnexal masses and compared to the model of Alcazar. Eighteen adnexal masses (13.8%) were malignant or of low malignant potential. Multivariate analysis showed that papillary projection of the tumor wall, cyst with solid parts, resistance index with a cut-off value of 0.53, CA 125, and central blood flow location, were the only factors to be independent predictors of malignancy. Menopausal status was not an independent factor. For the final model including the Doppler energy parameter the best sensitivity and specificity were 83% and 93%, respectively, at a cut-off value of 10% probability of malignancy compared to 83% and 87% for the morphological variables alone. Validation of the model showed its diagnostic performance to be as good as that reported in the original population and better than the model of Alcazar. Sonographic analysis of adnexal masses including color Doppler energy shows the

  10. Cerebral Hemodynamics in the Elderly: A Transcranial Doppler Study in the Einstein Aging Study Cohort.

    PubMed

    Yang, Dixon; Cabral, Digna; Gaspard, Emmanuel N; Lipton, Richard B; Rundek, Tatjana; Derby, Carol A

    2016-09-01

    We sought to describe the relationship between age, sex, and race/ethnicity with transcranial Doppler hemodynamic characteristics from major intracerebral arterial segments in a large elderly population with varying demographics. We analyzed 369 stroke-free participants aged 70 years and older from the Einstein Aging Study. Single-gate, nonimaging transcranial Doppler sonography, a noninvasive sonographic technique that assesses real-time cerebrovascular hemodynamics, was used to interrogate 9 cerebral arterial segments. Individual Doppler spectra and cerebral blood flow velocities were acquired, and the pulsatility index and resistive index were calculated by the device's automated waveform-tracking function. Multiple linear regression models were used to examine the independent associations of age, sex, and race/ethnicity with transcranial Doppler measures, adjusting for hypertension, history of myocardial infarction or revascularization, and history of diabetes. Among enrolled participants, 303 individuals had at least 1 vessel insonated (mean age [SD], 80 [6] years; 63% women; 58% white; and 32% black). With age, transcranial Doppler measures of mean blood flow velocity were significantly decreased in the basilar artery (P = .001) and posterior cerebral artery (right, P = .003; left, P = .02). Pulsatility indices increased in the left middle cerebral artery (P = .01) and left anterior cerebral artery (P = .03), and the resistive index was increased in the left middle cerebral artery (P = .007) with age. Women had higher pulsatility and resistive indices compared to men in several vessels. We report a decreased mean blood flow velocity and weakly increased arterial pulsatility and resistance with aging in a large elderly stroke-free population. These referential trends in cerebrovascular hemodynamics may carry important implications in vascular diseases associated with advanced age, increased risk of cerebrovascular disease, cognitive decline, and dementia.

  11. The effect of Ramadan fasting on fetal growth and Doppler indices of pregnancy.

    PubMed

    Moradi, Maryam

    2011-02-01

    The aim of this study was to determine the effect of Ramadan fasting on fetal growth and Doppler in-dices of pregnancy. Fifty two healthy pregnant women of second or third trimester, 25 in fasting group and 27 in non fasting group were included. Growth parameters including biparietal diameter (BPD), femoral length (FL), abdominal circumference (AC), estimated fetal weight, amniotic fluid index and also Doppler indices of both uterine and umbilical arteries (including peak systolic and end diastolic velocity, systolic to diastolic ratio, resistive and pulsatility indices) were evaluated by Gray scale and colour Doppler imaging for each women two times, in the beginning and at the end of Ramadan. Increases in BPD, FL, AC and fetal weight within one month were similar in two groups. Amniotic fluid index also were similar in two groups. There was not any statistically significant difference in abnormal Doppler indices of uterine or umbilical artery between two groups. The results of present study show that Ramadan fasting has no adverse effect on fetal growth, amniotic fluid volume or maternofetal circulation.

  12. Assessing prognosis of pulmonary embolism using tissue-Doppler echocardiography and brain natriuretic peptide

    PubMed Central

    Rodrigues, Ana Clara Tude; Cordovil, Adriana; Mônaco, Cláudia Gianini; Guimarães, Laise Antônia Bonfim; de Oliveira, Wércules Antônio Alves; Fischer, Claudio Henrique; de Lira, Edgar Bezerra; Vieira, Marcelo Luiz Campos; Morhy, Samira Saady

    2013-01-01

    ABSTRACT Objective: To assess prognosis of pulmonary thromboembolism using tissue Doppler echocardiography and brain natriuretic peptide. Methods: Patients aged over 18 years were evaluated within 24 hours of confirmed diagnosis (chest tomography/pulmonary scintigraphy) of pulmonary embolism using two-dimensional echocardiography and tissue Doppler for right ventricular systolic (s') velocities, strain, tissue tracking and myocardial performance index. Plasma brain natriuretic peptide was also obtained within 24 hour. The influence of echocardiographic and clinical variables on mortality was examined (up to 12 months) using Cox regression analysis. Results: Out of 118 patients, 100 patients were included in the study (60 males, aged 55±17 years). Right ventricular dysfunction was observed in 28% using two-dimensional echocardiography. Tissue Doppler right ventricular variables (s' velocities, tissue tracking and strain) were decreased only for patients with right ventricular dysfunction, whereas myocardial performance index and systolic pulmonary artery pressure were increased. Mean brain natriuretic peptide value was 66±111pg/mL, also increased in patients with right ventricular dysfunction (136±146pg/mL). Mortality was 11% and related to age, malignancy and brain natriuretic peptide levels. The only echocardiographic variables capable of predicting events by univariate analysis were pulmonary pressure and right ventricular s' velocity. However, multivariate analysis showed only malignancy to predict mortality in this group. Conclusion: Lower tissue Doppler systolic velocities and elevated brain natriuretic peptide levels are associated with poorer prognosis in patients with pulmonary thromboembolism; but only malignancy emerged as an independent predictor of mortality. PMID:24136761

  13. Ultrasonography with color Doppler and power Doppler in the diagnosis of periapical lesions

    PubMed Central

    Goel, Sumit; Nagendrareddy, Suma Gundareddy; Raju, Manthena Srinivasa; Krishnojirao, Dayashankara Rao Jingade; Rastogi, Rajul; Mohan, Ravi Prakash Sasankoti; Gupta, Swati

    2011-01-01

    Aim: To evaluate the efficacy of ultrasonography (USG) with color Doppler and power Doppler applications over conventional radiography in the diagnosis of periapical lesions. Materials and Methods: Thirty patients having inflammatory periapical lesions of the maxillary or mandibular anterior teeth and requiring endodontic surgery were selected for inclusion in this study. All patients consented to participate in the study. We used conventional periapical radiographs as well as USG with color Doppler and power Doppler for the diagnosis of these lesions. Their diagnostic performances were compared against histopathologic examination. All data were compared and statistically analyzed. Results: USG examination with color Doppler and power Doppler identified 29 (19 cysts and 10 granulomas) of 30 periapical lesions accurately, with a sensitivity of 100% for cysts and 90.91% for granulomas and a specificity of 90.91% for cysts and 100% for granulomas. In comparison, conventional intraoral radiography identified only 21 lesions (sensitivity of 78.9% for cysts and 45.4% for granulomas and specificity of 45.4% for cysts and 78.9% for granulomas). There was definite correlation between the echotexture of the lesions and the histopathological features except in one case. Conclusions: USG imaging with color Doppler and power Doppler is superior to conventional intraoral radiographic methods for diagnosing the nature of periapical lesions in the anterior jaws. This study reveals the potential of USG examination in the study of other jaw lesions. PMID:22223940

  14. A novel decision tree approach based on transcranial Doppler sonography to screen for blunt cervical vascular injuries.

    PubMed

    Purvis, Dianna; Aldaghlas, Tayseer; Trickey, Amber W; Rizzo, Anne; Sikdar, Siddhartha

    2013-06-01

    Early detection and treatment of blunt cervical vascular injuries prevent adverse neurologic sequelae. Current screening criteria can miss up to 22% of these injuries. The study objective was to investigate bedside transcranial Doppler sonography for detecting blunt cervical vascular injuries in trauma patients using a novel decision tree approach. This prospective pilot study was conducted at a level I trauma center. Patients undergoing computed tomographic angiography for suspected blunt cervical vascular injuries were studied with transcranial Doppler sonography. Extracranial and intracranial vasculatures were examined with a portable power M-mode transcranial Doppler unit. The middle cerebral artery mean flow velocity, pulsatility index, and their asymmetries were used to quantify flow patterns and develop an injury decision tree screening protocol. Student t tests validated associations between injuries and transcranial Doppler predictive measures. We evaluated 27 trauma patients with 13 injuries. Single vertebral artery injuries were most common (38.5%), followed by single internal carotid artery injuries (30%). Compared to patients without injuries, mean flow velocity asymmetry was higher for single internal carotid artery (P = .003) and single vertebral artery (P = .004) injuries. Similarly, pulsatility index asymmetry was higher in single internal carotid artery (P = .015) and single vertebral artery (P = .042) injuries, whereas the lowest pulsatility index was elevated for bilateral vertebral artery injuries (P = .006). The decision tree yielded 92% specificity, 93% sensitivity, and 93% correct classifications. In this pilot feasibility study, transcranial Doppler measures were significantly associated with the blunt cervical vascular injury status, suggesting that transcranial Doppler sonography might be a viable bedside screening tool for trauma. Patient-specific hemodynamic information from transcranial Doppler assessment has the potential to alter

  15. The leicester Doppler phantom--a digital electronic phantom for ultrasound pulsed Doppler system testing.

    PubMed

    Gittins, John; Martin, Kevin

    2010-04-01

    Doppler flow and string phantoms have been used to assess the performance of ultrasound Doppler systems in terms of parameters such as sensitivity, velocity accuracy and sample volume registration. However, because of the nature of their construction, they cannot challenge the accuracy and repeatability of modern digital ultrasound systems or give objective measures of system performance. Electronic Doppler phantoms are able to make use of electronically generated test signals, which may be controlled precisely in terms of frequency, amplitude and timing. The Leicester Electronic Doppler Phantom uses modern digital signal processing methods and field programmable gate array technology to overcome some of the limitations of previously described electronic phantoms. In its present form, it is able to give quantitative graphical assessments of frequency response and range gate characteristics, as well as measures of dynamic range and velocity measurement accuracy. The use of direct acoustic coupling eliminates uncertainties caused by Doppler beam effects, such as intrinsic spectral broadening, but prevents their evaluation.

  16. Comparison of foetomaternal circulation in normal pregnancies and pregnancy induced hypertension using color Doppler studies.

    PubMed

    Gupta, Shikha; Misra, R; Ghosh, U K; Gupta, V; Srivastava, D

    2014-01-01

    The aim of present study was to assess fetomaternal blood flows in normal and abnormal pregnancies using color Doppler indices. Subjects were divided into two groups as: Group A of 25 subjects of normal pregnancy as controls and group B of 25 subjects of pregnancy induced hypertension. All the subjects were lying in the age-group of 25-35 years and having 28 to 34 weeks of gestation; the patients were evaluated by detailed history and were subjected to complete general examination. Blood pressure was taken on two occasions at least 6 hours apart. Systemic examination and obstetrical examination was done in all subjects. All cases were subjected to pathological tests- Haemogram, Test for proteins in urine. Ultrasound assessment of fetal growth was done by measuring BPD (Biparietal diameter), HC (Head circumference), FL (Femur length) and AC (Abdominal circumference): Average gestational age and effective fetal weight was then calculated by ultrasound machine. Color Doppler was used to assess the various Doppler indices indices: Pulsatility index (PI), Resistive index (RI) and Systolic diastolic ratio (S/D ratio) in bilateral uterine, umbilical and middle cerebral arteries and compared to the standard normograms. Percentage of subjects having abnormal Doppler indices were calculated. Assessment of percentage of SGA (small for gestational age) fetuses was done in all the three groups. Decline in mean values of all Doppler indices was found with advancing gestational age in normal pregnancy suggesting decreased vascular resistance and increased blood flow in fetomaternal circulation. In pregnancy induced hypertensives, the mean values of Doppler indices showed a decline as in normal pregnancy but showed an increase (more than 2 S.D. of the mean) for that gestational age in comparison to the control group suggesting increased impedance to blood flow in uteroplacental and fetomaternal circulation. Umbilical artery Doppler indices were found to be the most sensitive

  17. [Doppler evaluation of diastolic function in hypertrophic cardiomyopathy].

    PubMed

    Borzi, M; Capria, A; Calò, L; Luzi, M; Cannata, D

    1995-01-01

    Diastolic function may play a significant role in patients affected by hypertrophic cardiomyopathy, because abnormalities in diastolic function, even in presence of a normal systolic function, may determine the clinical features of the disease. Doppler ecocardiography, using a non-invasive and not highly expensive method, easily allows to analize the indexes of diastolic function, as soon as some morpho-functional parameters, represented by extent and localization of the myocardial hypertrophy and presence or absence of obstruction in the left ventricular outflow, which have always been considered relevant in the prognosis together with the typical arrhythmic abnormalities of the disease. The aim of this study was to investigate the behaviour of Doppler ecocardiographic parameters of diastolic function in 38 patients with hypertrophic cardiomyopathy and to analize whether they might be correlated with the morpho-functional patterns and clinical features of the disease, represented by the NYHA functional class and occurrence of ventricular tachycardia during 48 hour ambulatory electrocardiographic monitoring. Diastolic function abnormalities, although occurring in most patients, do not seem to be related with clinical conditions and/or with the typical morpho-functional patterns of the disease; however, an increase in the left atrial size together with a specific increase in the rate of deceleration of flow velocity in early diastole that were detected in patients with ventricular tachycardia, by suggesting a relation between diastolic dysfunction and arrhythmogenic substrate, remarks the importance of the analysis of diastolic function for a better prognostic evaluation of the hypertrophic cardiomyopathy.

  18. Blood flow Doppler velocimetry measured during active labor.

    PubMed

    Baron, Joel; Shwarzman, Polina; Sheiner, Eyal; Weintraub, Adi Y; Spiegel, Efrat; Sciaky, Yael; Dukler, Doron; Hershkovitz, Reli

    2015-04-01

    To evaluate blood flow Doppler velocimetry during the first and second stages of active labor. A prospective observational study was performed. Patients at term (37-42 weeks gestation), with normal fetal heart rate tracing patterns (categorized as category I) were examined during the first and second stages of labor. The sonographic parameters that were measured included the blood flow resistance of the maternal uterine artery (UtA) and umbilical artery (UA). Wilcoxon-matched pair test was used for the comparison of flows between the first and the second stages of labor. UtA and UA Doppler velocimetry measurements were obtained from 31 parturients. The left (LT) and right (RT) UtA pulsatility index (PI) was lower in the second stage of labor as compared with the first stage. However, only the LT side reached a statistically significant difference (0.88 ± 0.32 and 0.73 ± 0.18; P = 0.005). Compared with the first stage of labor, UA PI was significantly higher during the second stage of labor (0.72 ± 0.17 vs. 0.84 ± 0.33; respectively, P = 0.05). Significant blood flow resistance changes in maternal as well as in fetal blood vessels occur during the second stage as compared with the first stage of active labor.

  19. The diagnosis of endometriomas using colour Doppler energy imaging.

    PubMed

    Guerriero, S; Ajossa, S; Mais, V; Risalvato, A; Lai, M P; Melis, G B

    1998-06-01

    We studied the role of colour Doppler energy (CDE) (or power Doppler) imaging in the differentiation between endometriomas and other adnexal masses in premenopausal non-pregnant women. A total of 170 consecutive patients with persistent adnexal masses was submitted to B-mode transvaginal ultrasonography associated with CDE imaging evaluation. Plasma concentrations of CA125 were measured before surgery. Using CDE imaging evaluation of vessel distribution, the occurrence of one of the following findings was considered to indicate the likely presence of endometrioma: (i) a round-shaped homogeneous hypoechoic 'tissue' of low-level echoes without papillary proliferations associated with 'poor' vascularization; (ii) a round-shaped homogeneous hypoechoic 'tissue' of low-level echoes with an echogenic portion in which no flow was detected. The overall agreement between the test result and the actual outcome was calculated using the k index. The CDE imaging evaluation was more accurate in the diagnosis of endometriomas compared with B-mode ultrasonography alone (k = 0.88 and 0.80 respectively). According to the logistic regression equation obtained, the probability of the presence of endometrioma varied between a minimum of 1.4% for patients with no risk factors to a maximum of 95.6% for patients with two risk factors (CDE result and value of CA125 >25 IU/ml).

  20. Mechanism Analysis of the Inverse Doppler Effect in Two-Dimensional Photonic Crystal based on Phase Evolution.

    PubMed

    Jiang, Qiang; Chen, Jiabi; Wang, Yan; Liang, Binming; Hu, Jinbing; Zhuang, Songlin

    2016-04-22

    Although the inverse Doppler effect has been observed experimentally at optical frequencies in photonic crystal with negative effective refractive index, its explanation is based on phenomenological theory rather than a strict theory. Elucidating the physical mechanism underlying the inverse Doppler shift is necessary. In this article, the primary electrical field component in the photonic crystal that leads to negative refraction was extracted, and the phase evolution of the entire process when light travels through a moving photonic crystal was investigated using static and dynamic finite different time domain methods. The analysis demonstrates the validity of the use of np (the effective refractive index of the photonic crystal in the light path) in these calculations, and reveals the origin of the inverse Doppler effect in photonic crystals.

  1. Doppler-guided retrograde catheterization system

    NASA Astrophysics Data System (ADS)

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

    1991-05-01

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

  2. Color Doppler sonography in obstetrics and gynecology.

    PubMed

    Fleischer, Arthur C; Andreotti, Rochelle F

    2005-09-01

    This review aims to provide the reader with an overview of the present and future clinical applications in color Doppler sonography for the evaluation of vascularity and blood flow within the uterus (both gravid and nongravid), ovaries, fetus and placenta. The clinical use of color Doppler sonography has been demonstrated within many organ systems. Color Doppler sonography has become an integral part of cardiovascular imaging. Significant improvements have recently occurred, improving the visualization and evaluation of intra-organ vascularity, resulting from enhancements in delineation of tissue detail through electronic compounding and harmonics, as well as enhancements in signal processing of frequency- and/or amplitude-based color Doppler sonography. Spatial representation of vascularity can be improved by utilizing 3D and 4D (live 3D) processing. Greater sensitivity of color Doppler sonography to macro- and microvascular flow has provided improved anatomic and physiologic assessment throughout pregnancy and for pelvic organs. The potential use of contrast enhancement is also mentioned as a means to further differentiate benign from malignant ovarian lesions. The rapid development of these new sonographic techniques will continue to enlarge the scope of clinical applications in a variety of obstetric and gynecologic disorders.

  3. MP3 compression of Doppler ultrasound signals.

    PubMed

    Poepping, Tamie L; Gill, Jeremy; Fenster, Aaron; Holdsworth, David W

    2003-01-01

    The effect of lossy, MP3 compression on spectral parameters derived from Doppler ultrasound (US) signals was investigated. Compression was tested on signals acquired from two sources: 1. phase quadrature and 2. stereo audio directional output. A total of 11, 10-s acquisitions of Doppler US signal were collected from each source at three sites in a flow phantom. Doppler signals were digitized at 44.1 kHz and compressed using four grades of MP3 compression (in kilobits per second, kbps; compression ratios in brackets): 1400 kbps (uncompressed), 128 kbps (11:1), 64 kbps (22:1) and 32 kbps (44:1). Doppler spectra were characterized by peak velocity, mean velocity, spectral width, integrated power and ratio of spectral power between negative and positive velocities. The results suggest that MP3 compression on digital Doppler US signals is feasible at 128 kbps, with a resulting 11:1 compression ratio, without compromising clinically relevant information. Higher compression ratios led to significant differences for both signal sources when compared with the uncompressed signals. Copyright 2003 World Federation for Ultrasound in Medicine & Biology

  4. The EVE Doppler Sensitivity and Flare Observations

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  5. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    PubMed Central

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-01-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe. PMID:27578317

  6. The EVE Doppler Sensitivity and Flare Observations

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  7. Spacecraft Doppler Tracking as a Xylophone Detector

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo

    1996-01-01

    We discuss spacecraft Doppler tracking in which Doppler data recorded on the ground are linearly combined with Doppler measurements made on board a spacecraft. By using the four-link radio system first proposed by Vessot and Levine, we derive a new method for removing from the combined data the frequency fluctuations due to the Earth troposphere, ionosphere, and mechanical vibrations of the antenna on the ground. Our method provides also for reducing by several orders of magnitude, at selected Fourier components, the frequency fluctuations due to other noise sources, such as the clock on board the spacecraft or the antenna and buffeting of the probe by non-gravitational forces. In this respect spacecraft Doppler tracking can be regarded as a xylophone detector. Estimates of the sensitivities achievable by this xylophone are presented for two tests of Einstein's theory of relativity: searches for gravitational waves and measurements of the gravitational red shift. This experimental technique could be extended to other tests of the theory of relativity, and to radio science experiments that rely on high-precision Doppler measurements.

  8. Doppler Imaging of Exoplanets and Brown Dwarfs

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  9. Doppler estimation accuracy of linear FM waveforms

    NASA Astrophysics Data System (ADS)

    Daum, F. E.

    The single-pulse Doppler estimation accuracy of an unweighted linear FM waveform is analyzed in detail. Simple formulas are derived that predict that one-sigma Doppler estimation error for realistic radar applications. The effects of multiple target interference and nonlinearlities in the radar measurements are considered. In addition, a practical method to estimate Doppler frequency is presented. This technique uses the phase data after pulse compression, and it limits the effect of multiple target interference. In contrast, the available literature is based on the Cramer-Rao bound for Doppler accuracy, which ignores the effects of nonlinearities, multiple target interference and the question of practical implementation. A simple formula is derived that predicts the region of validity for the Cramer-Rao bound. This formula provides a criterion for minimum signal-to-noise ratio in terms of time-bandwidth product. Finally, an important concept that is demonstrated in this paper is that: the bulk of the Doppler information in a linear FM pulse is encoded in the range sidelobes after pulse compression.

  10. Doppler-corrected differential detection of MPSK

    NASA Technical Reports Server (NTRS)

    Simon, Marvin K.; Divsalar, Dariush

    1989-01-01

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

  11. Real-time virtual Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Khoshniat, Mahdieh; Thorne, Meghan L.; Poepping, Tamie L.; Holdsworth, David W.; Steinman, David A.

    2004-04-01

    Doppler ultrasound (DUS) is widely used to diagnose and plan treatments for vascular diseases, but the relationship between complex blood flow dynamics and the observed DUS signal is not completely understood. In this paper, we demonstrate that Doppler ultrasound can be realistically simulated in a real-time manner via the coupling of a known, previously computed velocity field with a simple model of the ultrasound physics. In the present case a 3D computational fluid dynamics (CFD) model of physiologically pulsatile flow a stenosed carotid bifurcation was interrogated using a sample volume of known geometry and power distribution. Velocity vectors at points within the sample volume were interpolated using a fast geometric search algorithm and, using the specified US probe characteristics and orientation, converted into Doppler shifts for subsequent display as a Doppler spectrogram or color DUS image. The important effect of the intrinsic spectral broadening was simulated by convolving the velocity at each point within the sample volume by a triangle function whose width was proportional to velocity. A spherical sample volume with a Gaussian power distribution was found to be adequate for producing realistic Doppler spectrogram in regions of uniform, jet, and recirculation flow. Fewer than 1000 points seeded uniformly within a radius comprising more than 99% of the total power were required, allowing spectra to be generated from high resolution CFD data at 100Hz frame rates on an inexpensive desktop workstation.

  12. Development of fiber optic laser Doppler velocimeter for measurement of local blood velocity

    NASA Astrophysics Data System (ADS)

    Ohba, Kenkich; Fujiwara, Noboru

    1993-08-01

    In order to measure the local velocity field in opaque fluid flows like blood flow, a new laser Doppler velocimeter having a pickup consisting of a small distributed index lens attached to the tips of two fibers which are joined side by side in parallel has been newly developed. The distributed index lens is the shape of a truncated cone. The flow field around this sensor has been measured very precisely by means of an ordinary LDV. The effect of turbidity of fluid on the quality of the laser Doppler signal from this sensor has been examined by experiments. As a result, it has been shown that this LDV sensor has a high signal-to-noise ratio, and that the disturbance against flow by the sensor is very small, and it is very promising as a velocity sensor for opaque or semi-opaque fluid flow like blood flow.

  13. Compression of polyphase codes with Doppler shift

    NASA Astrophysics Data System (ADS)

    Wirth, W. D.

    It is shown that pulse compression with sufficient Doppler tolerance may be achieved with polyphase codes derived from linear frequency modulation (LFM) and nonlinear frequency modulation (NLFM). Low sidelobes in range and Doppler are required especially for the radar search function. These may be achieved by an LFM derived phase coder together with Hamming weighting or by applying a PNL polyphase code derived from NLFM. For a discrete and known Doppler frequency with an expanded and mismatched reference vector a sidelobe reduction is possible. The compression is then achieved without a loss in resolution. A set up for the expanded reference gives zero sidelobes only in an interval around the signal peak or a least square minimization for all range elements. This version may be useful for target tracking.

  14. Doppler experiments with Cassini radio system

    NASA Technical Reports Server (NTRS)

    Comoretto, G.; Bertotti, B.; Iess, L.; Ambrosini, R.

    1992-01-01

    The radio system of the Cassini orbiter will include a K-alpha band downlink channel, mainly intended for telemetry. A K-alpha uplink has also been proposed to allow for a highly accurate gravitational wave experiment. The fourfold increase in frequency will reduce the plasma noise by a factor of 12 and will allow a Doppler accuracy better than 10 exp -15 for time scales of 10 exp 3 - 10 exp 4 s. Extensive Doppler measurements of the gravitational field of Saturn and its satellites can be performed, exploiting the induced change in the velocity of the spacecraft. Possible sources of low-frequency gravitational waves and errors in the Doppler link are discussed.

  15. Wide Angle Michelson Doppler Imaging Interferometer (WAMDII)

    NASA Technical Reports Server (NTRS)

    Roberts, W. T.

    1985-01-01

    The wide angle Michelson Doppler imaging interferometer (WAMDII) is a specialized type of optical Michelson interferometer working at sufficiently long path difference to measure Doppler shifts and to infer Doppler line widths of naturally occurring upper atmospheric Gaussian line emissions. The instrument is intended to measure vertical profiles of atmospheric winds and temperatures within the altitude range of 85 km to 300 km. The WAMDII consists of a Michelson interferometer followed by a camera lens and an 85 x 106 charge coupled device photodiode array. Narrow band filters in a filter wheel are used to isolate individual line emissions and the lens forms an image of the emitting region on the charge coupled device array.

  16. Wide Angle Michelson Doppler Imaging Interferometer (WAMDII)

    NASA Technical Reports Server (NTRS)

    Roberts, B.

    1986-01-01

    The wide angle Michelson Doppler imaging interferometer (WAMDII) is a specialized type of optical Michelson interferometer working at sufficiently long path difference to measure Doppler shifts and to infer Doppler line widths of naturally occurring upper atmospheric Gaussian line emissions. The instrument is intended to measure vertical profiles of atmospheric winds and temperatures within the altitude range of 85 km to 300 km. The WAMDII consists of a Michelson interferometer followed by a camera lens and an 85 x 106 charge coupled device photodiode array. Narrow band filters in a filter wheel are used to isolate individual line emissions and the lens forms an image of the emitting region on the charge coupled device array.

  17. Doppler effect in Schwarzschild and Kerr geometries

    NASA Astrophysics Data System (ADS)

    Radosz, A.; Augousti, A. T.; Ostasiewicz, K.

    2008-03-01

    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.

  18. Inline Ultrasonic Rheometry by Pulsed Doppler

    SciTech Connect

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

    2006-12-22

    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).

  19. Laser Doppler vibrometry measurement of the mechanical myogram

    NASA Astrophysics Data System (ADS)

    Rohrbaugh, John W.; Sirevaag, Erik J.; Richter, Edward J.

    2013-12-01

    Contracting muscles show complex dimensional changes that include lateral expansion. Because this expansion process is intrinsically vibrational, driven by repetitive actions of multiple motor units, it can be sensed and quantified using the method of Laser Doppler Vibrometry (LDV). LDV has a number of advantages over more traditional mechanical methods based on microphones and accelerometers. The LDV mechanical myogram from a small hand muscle (the first dorsal interosseous) was studied under conditions of elastic loading applied to the tip of the abducted index finger. The LDV signal was shown to be related systematically to the level of force production, and to compare favorably with conventional methods for sensing the mechanical and electrical aspects of muscle contraction.

  20. Effects of transducer, velocity, Doppler angle, and instrument settings on the accuracy of color Doppler ultrasound.

    PubMed

    Stewart, S F

    2001-04-01

    The accuracy of a commercial color Doppler ultrasound (US) system was assessed in vitro using a rotating torus phantom. The phantom consisted of a thin rubber tube filled with a blood-mimicking fluid, joined at the ends to form a torus. The torus was mounted on a disk suspended in water, and rotated at constant speeds by a motor. The torus fluid was shown in a previous study to rotate as a solid body, so that the actual fluid velocity was dependent only on the motor speed and sample volume radius. The fluid velocity could, thus, be easily compared to the color Doppler-derived velocity. The effects of instrument settings, velocity and the Doppler angle was assessed in four transducers: a 2.0-MHz phased-array transducer designed for cardiac use, a 4.0-MHz curved-array transducer designed for general thoracic use, and two linear transducers designed for vascular use (one 4.0 MHz and one 6.0 MHz). The color Doppler accuracy was found to be significantly dependent on the transducer used, the pulse-repetition frequency and wall-filter frequency, the actual fluid velocity and the Doppler angle (p < 0.001 by analysis of variance). In particular, the phased array and curved array were observed to be significantly more accurate than the two linear arrays. The torus phantom was found to provide a sensitive measure of color Doppler accuracy. Clinicians need to be aware of these effects when performing color Doppler US exams.

  1. A comparison of Doppler waveform parameters versus flow-mediated vascular dilation of the brachial artery in pregnant women.

    PubMed

    Landres, Inna V; Small, Maria; Sirjusingh, Adesh; Ramsewak, Samuel; Williams, Keith P

    2014-07-01

    Flow mediated dilation of the brachial artery is impaired with endothelial dysfunction. We previously identified that brachial artery waveforms were changed in preeclamptic women. We therefore sought to compare Doppler waveform analysis with flow mediated vascular dilation (FMVD) measurements in pregnant women. A cross sectional study of 71 pregnant women at >20weeks gestation comparing FMVD measurements with Doppler waveform parameters was performed. Research was conducted at three hospitals and two geographic settings; (1) Yale-New Haven Hospital in New Haven, CT, (2) Mount Hope Maternity and (3) Port of Spain General Hospital in Trinidad. Brachial artery Doppler waveform measurements were done at baseline and 90s post cuff-release. From the Doppler waveforms we assessed percent change in Peak Systolic Velocity (% ΔPSV), systolic acceleration, acceleration time and pulsatility index and compared them with the percent change in FMVD. Statistical analysis using Student's t tests and correlation coefficient was done as necessary. Correlation analysis between the % change in the Doppler waveform parameters and the % change in mean FMVD identified only the waveform parameter of % ΔPSV as significantly correlated (p=0.040). FMVD remains the gold standard for assessment of endothelial dysfunction. A correlation was observed between the Doppler measured % ΔPSV and FMVD, which may allow it to be used to assess endothelial dysfunction changes under different conditions was identified. Copyright © 2014 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved.

  2. Progression of Doppler changes in early-onset small for gestational age fetuses. How frequent are the different progression sequences?

    PubMed

    Morales-Roselló, José; Khalil, Asma; Fornés-Ferrer, Victoria; Alberola-Rubio, José; Hervas-Marín, David; Peralta Llorens, Núria; Perales-Marín, Alfredo

    2017-03-27

    To evaluate the progression of Doppler abnormalities in early-onset fetal smallness (SGA). A total of 948 Doppler examinations of the umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV), belonging to 405 early-onset SGA fetuses, were studied, evaluating the sequences of Doppler progression, the interval examination-labor at which Doppler became abnormal and the cumulative sum of Doppler anomalies in relation with labor proximity. The most frequent sequences were that in which only the UA pulsatility index (PI) became abnormal (42.1%) and that in which an abnormal UA PI appeared first, followed by an abnormal MCA PI (24.2%). In general, 71.3% of the fetuses followed the classical progression sequence UA→MCA→DV, mostly in the early stages of growth restriction (84.1%). In addition, the UA PI was the first parameter to be affected (9 weeks before delivery), followed by the MCA PI and the DV PIV (1 and 0 weeks). Finally, the UA PI began to sum anomalies 5 weeks before delivery, while the MCA and DV did it at 3 and 1 weeks before the pregnancy ended. In early-onset SGA fetuses, Doppler progression tends to follow a predictable order, with sequential changes in the umbilical, cerebral and DV impedances.

  3. Ultrasonographic Doppler Use for Female Reproduction Management.

    PubMed

    Bollwein, Heinrich; Heppelmann, Maike; Lüttgenau, Johannes

    2016-03-01

    Transrectal color Doppler ultrasonography is a useful technique to get new information about physiologic and pathophysiologic alterations of the uterus and ovaries in female cattle. During all reproductive stages characteristic changes in uterine blood flow are observed. Cows with puerperal disturbances show delayed decrease in uterine blood flow in the first few weeks postparturition compared with healthy cows. Measurement of follicular blood flow is used to identify normally developing follicles and predict superovulatory response. Determination of luteal blood is more reliable than B-mode sonography to distinguish between functional and nonfunctional corpora lutea. Color Doppler ultrasonography is a promising tool to improve reproductive management in female cattle.

  4. Laser Doppler distance sensor using phase evaluation.

    PubMed

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

    2009-02-16

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

  5. Broad-band acoustic Doppler current profiler

    USGS Publications Warehouse

    Cobb, E.D.

    1993-01-01

    The broad-band acoustic Doppler current profiler is an instrument that determines velocity based on the Doppler principle by reflecting acoustic signals off sediment particles in the water. The instrument is capable of measuring velocity magnitude and direction throughout a water column and of measuring water depth. It is also capable of bottom tracking and can, therefore, keep track of its own relative position as it is moved across a channel. Discharge measurements can be made quickly and, based on limited tests, accurately with this instrument. ?? 1993.

  6. Laser Doppler Velocimeter particle velocity measurement system

    SciTech Connect

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

    1993-10-01

    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.

  7. Laser Doppler velocimeter aerial spray measurements

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  8. Velocity precision measurements using laser Doppler anemometry

    NASA Astrophysics Data System (ADS)

    Dopheide, D.; Taux, G.; Narjes, L.

    1985-07-01

    A Laser Doppler Anemometer (LDA) was calibrated to determine its applicability to high pressure measurements (up to 10 bars) for industrial purposes. The measurement procedure with LDA and the experimental computerized layouts are presented. The calibration procedure is based on absolute accuracy of Doppler frequency and calibration of interference strip intervals. A four-quadrant detector allows comparison of the interference strip distance measurements and computer profiles. Further development of LDA is recommended to increase accuracy (0.1% inaccuracy) and to apply the method industrially.

  9. Laser Doppler And Range Systems For Spacecraft

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  10. Development of Doppler Global Velocimeter (DGV)

    DTIC Science & Technology

    1998-05-01

    Dissertation, Wichita State University, May, 1995. Q«M?7 A301 ’ E’ a’IdI MilleI’ L; S-’ "Eva,uation of a Basic Doppler Global Velocimetry System," SAE...200 words) A two-component Doppler Global Velocimeter (DGV) and a two-component Point Doppier Velocimeter (PDV) are descried Velocity measurements...for both systems to quantify accuracy are presented. Results are presented for velocity distributions over the surface of a rotating wheel and fully

  11. Utility of Placental Laterality and Uterine Artery Doppler Abnormalities for Prediction of Preeclampsia.

    PubMed

    Yousuf, Shagufta; Ahmad, Abida; Qadir, Shazia; Gul, Sabia; Tali, Showkat Hussain; Shaheen, Feroz; Akhtar, Shareefa; Dar, Rayees

    2016-10-01

    To find out whether placental laterality and abnormal uterine artery waveform and resistance index, as determined by antenatal ultrasonography and Doppler, can be used as a predictor for the development of preeclampsia. This prospective observational cohort study was conducted from August 2013 to October 2014. Two hundred and one (201) normotensive, primigravida women with singleton pregnancies attending the antenatal clinics without any high-risk factor for development of hypertension were subjected to ultrasonography at 18-22 weeks of gestation to determine the placenta location. All the subjects with lateral placentas were subjected to Doppler ultrasonography to look for abnormal Doppler waveform and resistance index. They were followed for the development of preeclampsia till 40 weeks of gestation or delivery. Out of the total 201 women, 71 (24.5 %) had laterally located placentas and of them 37 (52 %) developed preeclampsia, while the remaining 130 (75.5 %) had centrally located placentas and of them 14 (10.8 %) developed preeclampsia (p < 0.001). In subjects with lateral placentas alone (n = 33), 2 (6 %) developed preeclampsia while as those with lateral placentas with Doppler abnormality (n = 38), 35 (92 %) developed preeclampsia (p < 0.001). The overall risk of developing preeclampsia with laterally located placenta was 9.27 (odds ratio), and 95 % confidence interval was (4.30-19.98). Pregnant women with lateral placentas are at significant risk for development of preeclampsia. Lateral placentas when associated with uterine artery Doppler abnormality, risk for development of preeclampsia increases significantly as compared to lateral placentas alone.

  12. Quantification of blood perfusion using 3D power Doppler: an in-vitro flow phantom study

    NASA Astrophysics Data System (ADS)

    Raine-Fenning, N. J.; Ramnarine, K. V.; Nordin, N. M.; Campbell, B. K.

    2004-01-01

    Three-dimensional (3D) power Doppler data is increasingly used to assess and quantify blood flow and tissue perfusion. The objective of this study was to assess the validity of common 3D power Doppler ‘vascularity’ indices by quantification in well characterised in-vitro flow models. A computer driven gear pump was used to circulate a steady flow of a blood mimicking fluid through various well characterised flow phantoms to investigate the effect of the number of flow channels, flow rate, depth dependent tissue attenuation, blood mimic scatter particle concentration and ultrasound settings. 3D Power Doppler data were acquired with a Voluson 530D scanner and 7.5 MHz transvaginal transducer (GE Kretz). Virtual Organ Computer-aided Analysis software (VOCAL) was used to quantify the vascularisation index (VI), flow index (FI) and vascularisation-flow index (VFI). The vascular indices were affected by many factors, some intuitive and some with more complex or unexpected relationships (e.g. VI increased linearly with an increase in flow rate, blood mimic scatter particle concentration and number of flow channels, and had a complex dependence on pulse repetition frequency). Use of standardised settings and appropriate calibration are required in any attempt at relating ‘vascularity indices’ with flow.

  13. Changes in Doppler parameters of portal pressure after interventional management of hepatocellular carcinoma.

    PubMed

    El Sherbiny, Walid; AbdelRahman, Ashraf; Diasty, Muhammad; Shaltout, Shaker Wagih

    2016-08-01

    Hepatocellular carcinoma (HCC) has many options for management; some of them are complicated by development of portal hypertension (PHT). Doppler ultrasound is an effective method to diagnose and monitor PHT changes after HCC ablation procedures. The aim of this study is to investigate changes in portal pressure hemodynamics of HCC patients following treatment with different interventional strategies: radiofrequency ablation (RFA), microwave ablation (MWA), and transarterial chemoembolization (TACE). A total of 60 patients with HCC were divided into three main groups, and each group received a different type of therapy (RFA, MWA, and TACE). Full medical record and basic investigations were performed including Doppler ultrasound and upper GIT endoscopy for evaluation of PHT parameters, and then repeated after three months of ablation. RFA is associated with the increased splenic artery resistive index, while MWA has no significant impact on PHT indices. TACE has led to a marked increase in liver vascular index with significant decrease in hepatic artery resistive index and PHI after treatment. No significant changes in esophageal varices were observed by upper GIT endoscopy following all ablation methods. RFA is quite safe but associated with degree of PHT. On the contrary, TACE is associated with improved PHT parameters. MWA has no significant association to development of PHT following the technique. Doppler ultrasound could be used as a reliable and effective method of evaluation of PHT post ablation for HCC.

  14. SonTek SL3G Side-Looking Doppler Current Meter application in Complex Flow Conditions

    NASA Astrophysics Data System (ADS)

    Wagenaar, D.

    2014-12-01

    The SonTek Argonaut SL Side-Looking Doppler Current Meters are well established products in the measurement of real-time water velocity in open channels. With the development of acoustic doppler technology the decision was made to incorporate latest technology in the Argonaut SL and hence the SonTek SL3G was born.The SonTek SL3G Acoustic Doppler instrument incorporates a number of innovations that improves velocity measurements and quality assurance of data for Side-Looking Doppler Current Meters. SmartPulseHD was originally introduced with the launch of the SonTek M9/S5 RiverSurveyor Acoustic Doppler Instruments and the increased accuracy and resolution of velocity measurements made it obvious to include into the new SL3G instruments. SmartPulseHD continuously tracks the water conditions and selects the optimum processing configuration required using multiple ping types and processing techniques. The new SL3G design makes it the smallest Side Looking Acoustic Doppler Velocity Meter on the market reducing flow disturbance caused by the instrument and the distance of first measurement cell from boundary.The application of the SL3G Acoustic Doppler instrument is designed for complex flow conditions where the use of conventional stage-discharge relationships is economically not viable and therefore requires the use of velocity index methodology. The case-study presented in this paper is situated in the Colorado River downstream of Imperial Dam affected by controlled releases, drainage from adjacent irrigation areas and backwater from a weir situated downstream of the monitoring site. The paper analyses the relationship between measured mean velocity and index velocity and if additional variables such as stage and or Y-velocity need to be incorporated in the development of the index velocity rating. In addition, to determine the variables impacting on the index velocity rating, the index velocity applied will be evaluated by the best linear relationship between the

  15. Photoacoustic Doppler flow measurement in optically scattering media

    NASA Astrophysics Data System (ADS)

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.

    2007-12-01

    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microcirculation with high sensitivity.

  16. Acoustic micro-Doppler radar for human gait imaging.

    PubMed

    Zhang, Zhaonian; Pouliquen, Philippe O; Waxman, Allen; Andreou, Andreas G

    2007-03-01

    A portable acoustic micro-Doppler radar system for the acquisition of human gait signatures in indoor and outdoor environments is reported. Signals from an accelerometer attached to the leg support the identification of the components in the measured micro-Doppler signature. The acoustic micro-Doppler system described in this paper is simpler and offers advantages over the widely used electromagnetic wave micro-Doppler radars.

  17. Uterine Artery Doppler Velocimetry of Uterine Leiomyomas in Nigerian Women.

    PubMed

    Idowu, Bukunmi Michael; Ibitoye, Bolanle Olubunmi; Adetiloye, Victor Adebayo

    2017-09-01

    Objective To describe the blood flow velocities and impedance indices changes in the uterine arteries of leiomyomatous uteri using Doppler sonography. Methods This was a prospective, case-control study conducted on 140 premenopausal women with sonographic diagnosis of uterine leiomyoma and 140 premenopausal controls without leiomyomas. Pelvic sonography was performed to diagnose and characterize the leiomyomas. The hemodynamics of the ascending branches of both main uterine arteries was assessed by Doppler interrogation. Statistical analysis was performed mainly using non-parametric tests. Results The median uterine volume of the subjects was 556 cm(3), while that of the controls was 90.5 cm(3) (p < 0.001). The mean peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged maximum velocity (TAMX), time-averaged mean velocity (Tmean), acceleration time (AT), acceleration index (AI), diastolic/systolic ratio (DSR), diastolic average ratio (DAR), and inverse pulsatility index (PI) were significantly higher in the subjects (94.2 cm/s, 29.7 cm/s, 49.1 cm/s, 25.5 cm/s, 118 ms, 0.8, 0.3, 0.6, and 0.8 respectively) compared with the controls (54.2 cm/s, 7.7 cm/s, 20.0 cm/s, 10.0 cm/s, 92.0 ms, 0.6, 0.1, 0.4, and 0.4 respectively); p < 0.001 for all values. Conversely, the mean PI, resistivity index (RI), systolic/diastolic ratio (SDR) and impedance index (ImI) of the subjects (1.52, 0.70, 3.81, and 3.81 respectively) were significantly lower than those of the controls (2.38, 0.86, 7.23, and 7.24 respectively); p < 0.001 for all values. Conclusion There is a significantly increased perfusion of leiomyomatous uteri that is most likely due to uterine enlargement. Thieme Revinter Publicações Ltda Rio de Janeiro, Brazil.

  18. Atmospheric laser Doppler velocimetry - An overview

    NASA Technical Reports Server (NTRS)

    Bilbro, J. W.

    1980-01-01

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

  19. Tissue Doppler imaging in cardiac sarcoidosis.

    PubMed

    Smedema, J P

    2008-07-01

    A middle-aged African lady, who presented with ventricular tachycardias, mitral valve regurgitation and congestive heart failure, was diagnosed with cardiac sarcoidosis. Tissue Doppler imaging demonstrated abnormalities suggestive of myocardial scar, which was confirmed by contrast-enhanced cardiac magnetic resonance.

  20. Method for Canceling Ionospheric Doppler Effect

    NASA Technical Reports Server (NTRS)

    Vessot, R. F. C.

    1982-01-01

    Unified transponder system with hydrogen-maser oscillators at both stations can compensate for both motional and ionospheric components of Doppler shift. Appropriate choices of frequency shift in output of mixer m3. System exploits proportionality between dispersive component of frequency shift and reciprocal of frequency to achieve cancellation of dispersive component at output.

  1. Calculating "g" from Acoustic Doppler Data

    ERIC Educational Resources Information Center

    Torres, Sebastian; Gonzalez-Espada, Wilson J.

    2006-01-01

    Traditionally, the Doppler effect for sound is introduced in high school and college physics courses. Students calculate the perceived frequency for several scenarios relating a stationary or moving observer and a stationary or moving sound source. These calculations assume a constant velocity of the observer and/or source. Although seldom…

  2. Satellite Doppler data processing using a microcomputer

    NASA Technical Reports Server (NTRS)

    Schmid, P. E.; Lynn, J. J.

    1977-01-01

    A microcomputer which was developed to compute ground radio beacon position locations using satellite measurements of Doppler frequency shift is described. Both the computational algorithms and the microcomputer hardware incorporating these algorithms were discussed. Results are presented where the microcomputer in conjunction with the NIMBUS-6 random access measurement system provides real time calculation of beacon latitude and longitude.

  3. Acoustic Doppler discharge-measurement system

    USGS Publications Warehouse

    Simpson, Michael R.; Oltmann, Richard N.; ,

    1990-01-01

    A discharge-measurement system that uses a vessel-mounted acoustic Doppler current profiler has been developed and tested by the U.S. Geological Survey. Discharge measurements using the system require a fraction of the time needed for conventional current-meter discharge measurements and do not require shore-based navigational aids or tag lines for positioning the vessel.

  4. Thyroid Doppler US: Tips and tricks.

    PubMed

    Lacout, Alexis; Chevenet, Carole; Salas, Joël; Marcy, Pierre Yves

    2016-04-01

    Incidental diagnosis of thyroid nodules is very common on adult neck ultrasonography (US) examination. They are primarily assessed on size and greyscale ultrasound criteria such as hypoechogenicity, taller than wide, spiculated margins and calcifications. In difficult situations Doppler US features may improve tumour characterisation and staging. © 2015 The Royal Australian and New Zealand College of Radiologists.

  5. Investigations of Near-Zone Doppler Effects.

    NASA Astrophysics Data System (ADS)

    Prouty, Dale Austen

    Far away from an electromagnetic source the normal Doppler shifts in frequency occur--a red shift for receding and a blue shift for approaching. As indicated by previous work with an infinitesimal dipole, different frequency shifts occur when the source and observer move closer together, into the near-zone. These "near-zone Doppler effects" are investigated for general sources and subsequently two specific examples are presented. The general results show that near-zone shifts are similar to far-zone shifts, but the local phase velocity must be used, i.e. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). In the far zone the phase velocity is the speed of light; in the near zone it differs. Fundamentally, the distance between surfaces of constant phase in the near zone is changed. The surfaces of constant phase for the waves are no longer spherical, but more ellipsoidal or spheroidal, so that a moving observer sees a different frequency shift. Two specific examples are presented to indicate the actual magnitude of near-zone effects. The examples include a prolate spheroidal antenna and a circular aperture. Once the magnitude of the effects is determined, the measurability of near-zone Doppler effects is discussed. The investigation concentrates on Fresnel zone effects due to the measurement problem. Finally, it is shown that for an electrically large wire antenna (the spheroidal example) near-zone Doppler effects are measurable.

  6. Rubidium Atomic Line Filtered (RALF) Doppler Velocimetry

    NASA Astrophysics Data System (ADS)

    Fajardo, Mario; Molek, Christopher; Vesely, Annamaria

    2015-06-01

    We report the successful proof-of-concept demonstration of the Rubidium Atomic Line Filtered (RALF) Doppler velocimetry technique. RALF is a high-velocity and high-acceleration adaptation of the Global Doppler Velocimetry (GDV) method developed in the 1990s by aerodynamics researchers. Laser velocimetry techniques in common use within the shock physics community (e . g . VISAR, Fabry-Perot, PDV) decode the Doppler shift of light reflected from a moving surface via interference phenomena. In contrast, RALF employs a completely different physical principle: the frequency-dependent near-resonant optical transmission of a Rb/N2 gas cell, to convert the Doppler shift of reflected λ0 ~ 780.24 nm light directly into transmitted light intensity. The single-point RALF apparatus used in these experiments is fiber optic based, and incorporates a simultaneous PDV measurement channel as an ``internal standard'' for validation of the RALF results. Future plans include ``line-RALF'' experiments with streak camera detection, and two-dimensional surface velocity mapping using pulsed laser illumination and gated intensified CCD camera detection. [RW PA#4931

  7. Measurement of aortic regurgitation by Doppler echocardiography.

    PubMed Central

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

    1986-01-01

    In an attempt to develop a new approach to the non-invasive measurement of aortic regurgitation, transmitral volumetric flow (MF) and left ventricular total stroke volume (SV) were measured by Doppler and cross sectional echocardiography in 23 patients without aortic valve disease (group A) and in 26 patients with aortic regurgitation (group B). The transmitral volumetric flow was obtained by multiplying the corrected mitral orifice area by the diastolic velocity integral, and the left ventricular total stroke volume was derived by subtracting the left ventricular end systolic volume from the end diastolic volume. The aortic regurgitant fraction (RF) was calculated as: RF = 1 - MF/SV. In group A there was a close agreement between the transmitral volumetric flow and the left ventricular total stroke volume, and the difference between the two measurements did not differ significantly from zero. In group B the left ventricular total stroke volume was significantly larger than the transmitral volumetric flow, and there was good agreement between the regurgitant fractions determined by Doppler echocardiography and radionuclide ventriculography. Discrepancies between the two techniques were found in patients with combined aortic and mitral regurgitation or a low angiographic left ventricular ejection fraction (less than 35%). The effective cardiac output measured by Doppler echocardiography accorded well with that measured by the Fick method. Doppler echocardiography provides a new and promising approach to the non-invasive measurement of aortic regurgitation. PMID:3947478

  8. Tissue Doppler imaging reproducibility during exercise.

    PubMed

    Bougault, V; Nottin, S; Noltin, S; Doucende, G; Obert, P

    2008-05-01

    Tissue Doppler imaging (TDI) is an echocardiographic technique used during exercising to improve the accuracy of a cardiovascular diagnostic. The validity of TDI requires its reproducibility, which has never been challenged during moderate to maximal intensity exercising. The present study was specifically designed to assess the transmitral Doppler and pulsed TDI reproducibility in 19 healthy men, who had undergone two identical semi-supine maximal exercise tests on a cycle ergometer. Systolic (S') and diastolic (E') tissue velocities at the septal and lateral walls as well as early transmitral velocities (E) were assessed during exercise up to maximal effort. The data were compared between the two tests at 40 %, 60 %, 80 % and 100 % of maximal aerobic power. Despite upper body movements and hyperventilation, good quality echocardiographic images were obtained in each case. Regardless of exercise intensity, no differences were noticed between the two tests for all measurements. The variation coefficients for Doppler variables ranged from 3 % to 9 % over the transition from rest to maximal exercise. The random measurement error was, on average, 5.8 cm/s for E' and 4.4 cm/s for S'. Overall, the reproducibility of TDI was acceptable. Tissue Doppler imaging can be used to accurately evaluate LV diastolic and/or systolic function for this range of exercise intensity.

  9. Calculating "g" from Acoustic Doppler Data

    ERIC Educational Resources Information Center

    Torres, Sebastian; Gonzalez-Espada, Wilson J.

    2006-01-01

    Traditionally, the Doppler effect for sound is introduced in high school and college physics courses. Students calculate the perceived frequency for several scenarios relating a stationary or moving observer and a stationary or moving sound source. These calculations assume a constant velocity of the observer and/or source. Although seldom…

  10. Bibliography and index of U.S. Geological Survey trace elements and related reports through June 1956

    USGS Publications Warehouse

    Soister, Paul E.; Conklin, Dora R.; Bowman, Mary D.; ,

    1956-01-01

    This bibliography supersedes TEI-500, "U. S. Geological Survey Trace Elements and related reports through 1954." Part I is a numerical list of U. S. Geological Survey Trace Elements Investigations and Memorandum reports. This part lists reports that have been transmitted to the U. S. Atomic Energy Comission and also reports in preparation (followed by an asterisk) for which tentative titles were available on June 30, 1956. If a report or part of a report has been published, the fact is indicated by the abbreviation of the medium of publication. (See also Part II.) Part II is a reference guide to Trace Elements and related reports that are available to the public. (Part II supersedes Part I of Bulletin 1019-B.) These reports are grouped according to type of publication or release. If a report or part of a report has been published in more than one form, corss-references indicate the other forms of publication. Publications in preparation or in press on June 30, 1956, are designated by an asterisk. Part III is an author index. The words "with" and "and" are used to indicate seniority of authorship. For example, a listing of Black and White indicates that Black is the senior author. A listing of Black with White indicates that White is the senior author. Part IV is an index for finding reports on specific areas or subjects. Information for the index was taken from titles, tables of contents, and abstracts of unpublished reports and from titles of published reports. The index in TEI-500 was used as a guide.

  11. Reference values for pulse wave Doppler and tissue Doppler imaging in pediatric echocardiography.

    PubMed

    Dallaire, Frederic; Slorach, Cameron; Hui, Wei; Sarkola, Taisto; Friedberg, Mark K; Bradley, Timothy J; Jaeggi, Edgar; Dragulescu, Andreea; Har, Ronnie L H; Cherney, David Z I; Mertens, Luc

    2015-02-01

    In pediatric echocardiography, pulse wave Doppler, and tissue Doppler imaging velocities are widely used to assess cardiac function. Current reference values and Z scores, allowing adjustment for growth are limited by inconsistent methodologies and small sample size. Using a standardized approach for parametric modeling and Z score quality assessment, we propose new pediatric reference values and Z score equations for most left ventricular pulse wave Doppler and tissue Doppler imaging measurements. Two hundred thirty-three healthy pediatric subjects 1 to 18 years of age were prospectively recruited. Thirteen pulse wave Doppler and 14 tissue Doppler imaging measurements were recorded. Normalization for growth was done via a complete and standardized approach for parametric nonlinear regression modeling. Several analyses were performed to ensure adequate Z score distribution and to detect potential residual associations with growth or residual heteroscedasticity. Most measurements adopted a nonlinear relationship with growth and displayed significant heteroscedasticity. Compared with age, height, and weight, normalization for body surface area was most efficient in removing the effect of growth. Generally, polynomial and allometric models yielded adequate goodness-of-fit. Residual values for several measurements had significant departure from the normal distribution, which could be corrected using logarithmic or reciprocal transformation. Overall, weighted parametric nonlinear models allowed us to compute Z score equations with adequate normal distribution and without residual association with growth. We present Z scores for normalized pulse wave Doppler and tissue Doppler imaging in pediatric echocardiography. Further studies are needed to define the threshold beyond which health becomes a disease by integrating other important factors such as ventricular morphology, loading conditions, and heart rate. © 2015 American Heart Association, Inc.

  12. Activity of Crohn's disease assessed by colour Doppler ultrasound analysis of the affected loops.

    PubMed

    Esteban, J M; Maldonado, L; Sanchiz, V; Minguez, M; Benages, A

    2001-01-01

    The aim of this study was to evaluate with colour Doppler ultrasound the vascular changes in the wall of the loops affected by Crohn's disease, and to establish whether these changes reflects clinical or biochemical activity of Crohn's disease. Seventy-nine patients with Crohn's disease (44 with active disease and 35 inactive patients) were studied with frequency- and amplitude-encoded duplex Doppler sonography. A group of 35 healthy volunteers were also included. The exam consisted of the search for colour signals in the walls of the loops affected by Crohn's disease, classifying the degree of vascularity with a simple scoring system into three groups: absence of colour signal (score of 0); weak or scattered colour signals (score of 1); and multiple colour signals or clear identification of vessels in the loops walls (score of 2). Doppler curves were obtained of the detected vessels with measurement of the resistive index (RI). There was a visible increase in the gut walls' vascularity in the active patients compared with those with inactive disease. The mean RI was statistically significantly lower in the gut wall vessels of the patients with active illness than that obtained in the inactive patients. Colour Doppler ultrasound is a useful tool in the assessment of activity in Crohn's disease.

  13. Rubidium atomic line filtered (RALF) Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Fajardo, Mario E.; Molek, Christopher D.; Vesely, Annamaria L.

    2017-01-01

    We report recent improvements to our Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus [M.E. Fajardo, C.D. Molek, and A.L. Vesely, J. Appl. Phys. 118, 144901 (2015)]. RALF is a high-velocity and high-acceleration adaptation of the Doppler Global Velocimetry method for measuring multi-dimensional velocity vector flow fields, which was developed in the 1990s by aerodynamics researchers [H. Komine, U.S. Patent #4,919,536]. Laser velocimetry techniques in common use within the shock physics community (e.g. VISAR, Fabry-Pérot, PDV) decode the Doppler shift of light reflected from a moving surface via interference phenomena. In contrast, RALF employs a completely different physical principle: the frequency-dependent near-resonant optical transmission of a Rb/N2 gas cell, to encode the Doppler shift of reflected λ0 ≈ 780.24 nm light directly onto the transmitted light intensity. Thus, RALF is insensitive to minor changes to the optical pathlengths and transit times of the Doppler shifted light, which promises a number of practical advantages in imaging velocimetry applications. The single-point RALF proof-of-concept apparatus described here is fiber optic based, and our most recent modifications include the incorporation of a larger bandwidth detection system, and a second 780 nm laser for simultaneous upshifted-PDV (UPDV) measurements. We report results for the laser driven launch of a 10-μm-thick aluminum flyer which show good agreement between the RALF and UPDV velocity profiles, within the limitations of the admittedly poor signal:noise ratio (SNR) RALF data.

  14. A MAGNETIC CALIBRATION OF PHOTOSPHERIC DOPPLER VELOCITIES

    SciTech Connect

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

    2013-03-10

    The zero point of measured photospheric Doppler shifts is uncertain for at least two reasons: instrumental variations (from, e.g., thermal drifts); and the convective blueshift, a known correlation between intensity and upflows. Accurate knowledge of the zero point is, however, useful for (1) improving estimates of the Poynting flux of magnetic energy across the photosphere, and (2) constraining processes underlying flux cancellation, the mutual apparent loss of magnetic flux in closely spaced, opposite-polarity magnetogram features. We present a method to absolutely calibrate line-of-sight (LOS) velocities in solar active regions (ARs) near disk center using three successive vector magnetograms and one Dopplergram coincident with the central magnetogram. It exploits the fact that Doppler shifts measured along polarity inversion lines (PILs) of the LOS magnetic field determine one component of the velocity perpendicular to the magnetic field, and optimizes consistency between changes in LOS flux near PILs and the transport of transverse magnetic flux by LOS velocities, assuming that ideal electric fields govern the magnetic evolution. Previous calibrations fitted the center-to-limb variation of Doppler velocities, but this approach cannot, by itself, account for residual convective shifts at the limb. We apply our method to vector magnetograms of AR 11158, observed by the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory, and find clear evidence of offsets in the Doppler zero point in the range of 50-550 m s{sup -1}. In addition, we note that a simpler calibration can be determined from an LOS magnetogram and Dopplergram pair from the median Doppler velocity among all near-disk-center PIL pixels. We briefly discuss shortcomings in our initial implementation, and suggest ways to address these. In addition, as a step in our data reduction, we discuss the use of temporal continuity in the transverse magnetic field direction to correct apparently

  15. The Novel Nonlinear Adaptive Doppler Shift Estimation Technique and the Coherent Doppler Lidar System Validation Lidar

    NASA Technical Reports Server (NTRS)

    Beyon, Jeffrey Y.; Koch, Grady J.

    2006-01-01

    The signal processing aspect of a 2-m wavelength coherent Doppler lidar system under development at NASA Langley Research Center in Virginia is investigated in this paper. The lidar system is named VALIDAR (validation lidar) and its signal processing program estimates and displays various wind parameters in real-time as data acquisition occurs. The goal is to improve the quality of the current estimates such as power, Doppler shift, wind speed, and wind direction, especially in low signal-to-noise-ratio (SNR) regime. A novel Nonlinear Adaptive Doppler Shift Estimation Technique (NADSET) is developed on such behalf and its performance is analyzed using the wind data acquired over a long period of time by VALIDAR. The quality of Doppler shift and power estimations by conventional Fourier-transform-based spectrum estimation methods deteriorates rapidly as SNR decreases. NADSET compensates such deterioration in the quality of wind parameter estimates by adaptively utilizing the statistics of Doppler shift estimate in a strong SNR range and identifying sporadic range bins where good Doppler shift estimates are found. The authenticity of NADSET is established by comparing the trend of wind parameters with and without NADSET applied to the long-period lidar return data.

  16. Effect of food intake on commonly used pulsed Doppler and tissue Doppler measurements.

    PubMed

    Dencker, Magnus; Björgell, Ola; Hlebowicz, Joanna

    2011-09-01

    This study evaluates the effect of food intake on commonly used pulsed Doppler and tissue Doppler measurements. Twenty-three healthy subjects aged 25.6 ± 4.5 years were investigated. A wide selection of pulsed Doppler and tissue Doppler variables were measured before a standardized meal as well as and 30 and 110 minutes afterwards. The following variables increased significantly (P < 0.05) 30 minutes after food intake: left ventricular stroke volume, left ventricular cardiac output, left ventricular outflow velocity-time integral, peak of early diastolic (E) and late diastolic (A) mitral flow velocities, pulmonary vein peak velocities in systole (S) and in diastole (D), S/D, pulsed tissue Doppler peak systolic velocities, and late diastolic velocities. Deceleration time of E-wave decreased significantly (P < 0.05). The change in measured variables between fasting and 30 minutes after the food intake ranged from 7% to 28%. There were no significant (P > 0.05) changes in E/A, early diastolic tissue Doppler velocities (e'), and E/e'. Most, but not all variables returned to baseline values 110 minutes after food intake. This study shows that food intake affects several echocardiographic variables used to routinely assess diastolic function and hemodynamics. Further studies are warranted in older healthy subjects and in patients with various cardiac diseases to determine whether the findings are reproducible in such populations. © 2011, Wiley Periodicals, Inc.

  17. INDEXING MECHANISM

    DOEpatents

    Kock, L.J.

    1959-09-22

    A device is presented for loading and unloading fuel elements containing material fissionable by neutrons of thermal energy. The device comprises a combination of mechanical features Including a base, a lever pivotally attached to the base, an Indexing plate on the base parallel to the plane of lever rotation and having a plurality of apertures, the apertures being disposed In rows, each aperture having a keyway, an Index pin movably disposed to the plane of lever rotation and having a plurality of apertures, the apertures being disposed in rows, each aperture having a keyway, an index pin movably disposed on the lever normal to the plane rotation, a key on the pin, a sleeve on the lever spaced from and parallel to the index pin, a pair of pulleys and a cable disposed between them, an open collar rotatably attached to the sleeve and linked to one of the pulleys, a pin extending from the collar, and a bearing movably mounted in the sleeve and having at least two longitudinal grooves in the outside surface.

  18. Influence of Pulse Repetition Frequency on 3-D Power Doppler Quantification.

    PubMed

    Soares, Carlos A M; Pavan, Theo Z; Miyague, Andre H; Kudla, Marek; Martins, Wellington P

    2016-12-01

    Three-dimensional power Doppler quantification has limited application because of its high dependency on attenuation. The purpose of the study described here was to assess if different degrees of attenuation, depending on pulse repetition frequency (PRF) adjustment, alter 3-D power Doppler quantification in a region of 100% moving blood when using vascularization index, flow index and vascularization flow index (VFI). A cubic-shaped gelatin phantom with a 1.8-mm-internal-diameter silicon tube was used. The tube, placed at 45° to the phantom's surface, was filled with blood-mimicking fluid with as constant maximum velocity of 30 cm/s. Two different attenuation blocks (low and high attenuation) were alternatively placed between the phantom and the transvaginal transducer. One single observer acquired 10 data sets for each PRF level from 0.3 to 7.5 kHz, using the high- and low-attenuation blocks, for a total of 200 3-D power Doppler data sets. We assessed VFI from 1.5-mm-diameter spherical samples, virtually placed inside the tube, always at the same position. No difference was noted between high- and low-attenuation VFI values when using a PRF of 0.3 kHz. As PRF increased, it was observed that VFI quantification progressively differed between low and high attenuation. Also, a slope on VFI values for both high- and low-attenuation models could be observed when increasing PRF, particularly above 4.0 kHz. We concluded that PRF adjustment is very relevant when using VFI to quantify 3-D power Doppler signal.

  19. Experimental design and theoretical analysis on the proof experiment of the inverse Doppler effect at optical frequencies

    NASA Astrophysics Data System (ADS)

    Jiang, Qiang; Liang, Binming; Hu, Aiqing

    2013-08-01

    The proof experiment of inverse Doppler effect is simulated by idealizing optical field distribution of laser as fundamental mode Gaussian beam. Two key factors, the detecting area and the angle from light to normal of detecting surface, are analyzed. The proof experiment conducted recently by our research team successfully shows that the experimental data are consistent with theoretical data. Our work lays a solid foundation for the design of experimental system and the coming experiments on the mechanism of inverse Doppler effect in negative index materials.

  20. Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction.

    PubMed

    Baschat, A A; Gembruch, U; Reiss, I; Gortner, L; Weiner, C P; Harman, C R

    2000-10-01

    The aim of this investigation was to assess the relationship between abnormal arterial and venous Doppler findings and perinatal outcome in fetuses with intrauterine growth restriction (IUGR). Doppler velocimetry of the umbilical artery (UA), middle cerebral artery (MCA), inferior vena cava (IVC), ductus venosus (DV) and free umbilical vein was performed in 121 IUGR fetuses with a UA pulsatility index (PI) > 2 SD above the gestational age mean and subsequent birth weight < 10th centile for gestational age. Groups based on the last Doppler exam were: 1 = abnormal UA-PI only (n = 42, 34.7%), 2 = MCA-PI > 2 SD below the gestational age mean (= 'brain sparing') in addition to abnormal UA-PI (n = 29, 24.0%), 3 = DV or IVC peak velocity index (PVIV) > 2 SD above the gestational age mean and/or pulsatile UV flow (n = 50, 41.3%). Z-scores (delta indices) were calculated for Doppler indices. Perinatal mortality, respiratory distress (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), circulatory failure and umbilical artery blood gases were recorded. Absence or reversal of umbilical artery end-diastolic flow was observed in 4 (9.5%) of fetuses in group 1, 10 (34.5%) fetuses in group 2 and 41 (82%) fetuses in group 3. A low middle cerebral artery pulsatility index was found in 39 (78%) fetuses in group 3. Multiple regression analysis with gestational age at delivery, delta indices and cord artery blood gas as independent parameters and individual perinatal outcomes as dependent variables was performed. In this analysis the association was strongest with gestational age for each complication. There were no significant differences in Apgar scores between groups. At delivery, 'brain sparing' was associated with hypoxemia and abnormal venous flows with acidemia. Perinatal mortality was highest in group 3 and stillbirth was only observed when venous flow was abnormal. All postpartum complications were more frequent in

  1. Study of the development of uteroplacental and fetal feline circulation by triplex Doppler.

    PubMed

    Pereira, Barbara Sucupira; Pinto, José Nicodemos; Freire, Luma Morena Passos; Campello, Cláudio Cabral; Domingues, Sheyla Farhayldes Souza; da Silva, Lucia Daniel Machado

    2012-03-15

    The objective was to evaluate blood flow in fetal and maternal vessels by Triplex Doppler and its association with development of blood vessels during gestation in the domestic cat. Ten queens were examined weekly from 14 to 63 d after mating. Peak systolic velocity (PSV), end diastolic velocity (EDV), resistance index (RI) and pulsatility index (PI) of uteroplacental, aorta and umbilical fetal arteries and caudal vena cava of the fetus were evaluated. Throughout pregnancy, there was an increase in PSV and EDV in the aorta and umbilical arteries. In the caudal vena cava, there was an increase in PSV, whereas the EDV was constant, with a significant increase on Day 63. Peak systolic velocity and EDV of the uteroplacental artery reduced significantly on Day 63. Resistance index of the umbilical artery progressively decreased. In the aorta, this reduction was detected only on Day 42, with no defined pattern in the caudal vena cava and uteroplacental artery. Pulsatility index of the aorta varied. Although pulsatility increased in the caudal vena cava on Day 35 and remained elevated, pulsatility was significantly reduced in the umbilical artery by Day 63. The pulsatility index of the uteroplacental artery was constant (increased only on Day 63). Triplex Doppler evaluation could be a useful adjunct for prenatal care of pregnant queens, including assessment of vascular gestational development and prediction of gestational age.

  2. Transvaginal 3-d power Doppler ultrasound evaluation of the fetal brain at 10-13 weeks' gestation.

    PubMed

    Hata, Toshiyuki; Tanaka, Hirokazu; Noguchi, Junko

    2012-03-01

    The objective of this study was to measure the fetal brain volume (FBV) and vascularization and blood flow using transvaginal 3-D power Doppler (3DPD) ultrasound late in the first trimester of pregnancy. 3DPD ultrasound examinations with the VOCAL imaging analysis program were performed on 36 normal fetuses from 10-13 weeks' gestation. FBV and 3DPD indices related to the fetal brain vascularization (vascularization index [VI], flow index [FI] and vascularization flow index [VFI]) were calculated in each fetus. Intra- and interclass correlation coefficients and intra- and interobserver agreements of measurements were assessed. FBV was curvilinearly correlated well with the gestational age (R2 = 0.861, p < 0.0001). All 3-D power Doppler indices (VI, FI and VFI) showed no change at 10-13 weeks' gestation. FBV and all 3-D power Doppler indices (VI, FI and VFI) showed a correlation > 0.82, with good intra- and interobserver agreement. Our findings suggest that 3-D ultrasound is a superior means of evaluating the FBV in utero, and that 3-D power Doppler ultrasound histogram analysis may provide new information on the assessment of fetal brain perfusion.

  3. Preliminary tests of an airborne meteorological pulse Doppler radar

    NASA Astrophysics Data System (ADS)

    Trotter, B. L.; Strauch, R. G.; Frush, C. L.

    1980-05-01

    An X-band Doppler radar in the tail of a WP-3D research aircraft has been used to conduct tests which demonstrate that technology developed for ground-based Doppler radar can be applied to an airborne system. The Doppler spectra of meteorological targets and chaff have been measured with the airborne radar, and these measurements compared favorably with data obtained by wind sensors on the aircraft and with measurements made with a ground-based Doppler radar. This letter describes the airborne Doppler radar and the preliminary test results.

  4. [Echo-Doppler study of musical heart murmurs].

    PubMed

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

    1988-04-01

    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.

  5. Practicability of intraoperative microvascular Doppler sonography in aneurysm surgery.

    PubMed

    Firsching, R; Synowitz, H J; Hanebeck, J

    2000-09-01

    Inadvertent narrowing of parent or branching vessels is one major cause of unfavorable outcome from aneurysm surgery. Intraoperative micro-Doppler sonography of arterial brain vessels during surgery for cerebral aneurysms of the anterior circulation was performed in 50 patients and compared retrospectively with 50 patients, who were operated upon without micro-Doppler sonography. Intraoperative micro-Doppler sonography demonstrated the need for repositioning of the clip in 12 instances. Outcome after surgery with micro-Doppler sonography appeared slightly better than without. Micro-Doppler sonography is concluded to be a practicable adjunct to routine aneurysm surgery.

  6. Phase tracking for pulsar navigation with Doppler frequency

    NASA Astrophysics Data System (ADS)

    Xinyuan, Zhang; Ping, Shuai; Liangwei, Huang

    2016-12-01

    Doppler frequency in pulsar navigation is an effect caused by spacecraft and pulsar motion, which would worsen the pulsar navigation accuracy. To describe this influence, we establish the Doppler frequency measurement model based on pulsar timing. With this model, we describe the relationship between the phase estimation performance and the observation time when Doppler frequency exists. To reduce the pulsar navigation error due to the Doppler frequency, we designed the phase tracking loop for the pulsar navigation. The pulsar frequency can be modified before the phase estimation. As a result, the impact of the Doppler frequency could be lessened, and the observation interval lengths can be lengthened to improve the phase estimation performance.

  7. Clinical utility of third-trimester uterine artery Doppler in the prediction of brain hemodynamic deterioration and adverse perinatal outcome in small-for-gestational-age fetuses.

    PubMed

    Cruz-Martinez, R; Savchev, S; Cruz-Lemini, M; Mendez, A; Gratacos, E; Figueras, F

    2015-03-01

    To assess the clinical value of third-trimester uterine artery (UtA) Doppler ultrasound in the prediction of hemodynamic deterioration and adverse perinatal outcome in term small-for-gestational-age (SGA) fetuses. UtA Doppler parameters, cerebroplacental ratio (CPR) and fetal middle cerebral artery (MCA) pulsatility index (PI) were evaluated weekly, starting from the time of SGA diagnosis until 24 h before induction of labor, in a cohort of 327 SGA fetuses with normal umbilical artery PI (< 95th centile), delivered at > 37 weeks' gestation. Differences in the sequence of CPR and MCA-PI changes < 5th centile, between the group with normal UtA Doppler indices at diagnosis and those with abnormal UtA indices, were analyzed by survival analysis. In addition, the use of UtA Doppler value, alone or in combination with a brain Doppler scan before delivery, to predict the risk of Cesarean section, Cesarean section for non-reassuring fetal status (NRFS), neonatal acidosis and neonatal hospitalization was evaluated by logistic regression analysis, adjusted for gestational age at birth and birth-weight percentile. Abnormal UtA Doppler at diagnosis of SGA was associated with a higher risk of developing abnormal brain Doppler indices before induction of labor than in those with a normal UtA at diagnosis (62.7% vs 34.6%, respectively; P < 0.01). Compared to those with normal UtA Doppler indices, those with abnormal UtA Doppler findings were associated with a higher risk of intrapartum Cesarean section (52.2% vs 37.3%, respectively; P = 0.03), Cesarean section for NRFS (35.8% vs 23.1%, respectively; P = 0.03), neonatal acidosis (10.4% vs 7.7%, respectively; P = 0.47) and neonatal hospitalization (23.9% vs 16.5%, respectively; P = 0.16). Logistic regression analysis indicated that UtA Doppler findings were not significantly associated with adverse perinatal outcome independent of brain Doppler findings. UtA Doppler indices predict adverse perinatal

  8. Superharmonic microbubble Doppler effect in ultrasound therapy

    NASA Astrophysics Data System (ADS)

    Pouliopoulos, Antonios N.; Choi, James J.

    2016-08-01

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  104-5  ×  107 microbubbles ml-1) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s-1, prior to the onset of

  9. Superharmonic microbubble Doppler effect in ultrasound therapy.

    PubMed

    Pouliopoulos, Antonios N; Choi, James J

    2016-08-21

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  10(4)-5  ×  10(7) microbubbles ml(-1)) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s(-1), prior to the onset

  10. Superharmonic microbubble Doppler effect in ultrasound therapy

    PubMed Central

    Pouliopoulos, Antonios N; Choi, James J

    2016-01-01

    Abstract The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  104–5  ×  107 microbubbles ml−1) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75–366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s−1, prior to

  11. The use of colour-coded and spectral Doppler ultrasound in the differentiation of benign and malignant breast lesions.

    PubMed Central

    Peters-Engl, C.; Medl, M.; Leodolter, S.

    1995-01-01

    The aim of this study was to evaluate the role of colour-coded and spectral Doppler sonography to predict the benign or malignant nature of breast lesions. A total of 112 women with mammographically suspicious breast lesions were investigated prior to surgery. Thirty-nine breast carcinomas and 73 benign lesions were evaluated for the resistance index, pulsatility index and the flow velocity. A resistance index of > or = 0.70 was characteristic of malignant tumours with a sensitivity of 82% and a specificity of 81%. The positive predictive value was 70% and the negative predictive value 89%. Doppler sonography offers one possible method for further investigation of patients with mammographic abnormalities. PMID:7819029

  12. Normal Echocardiographic Measurements in a Korean Population Study: Part II. Doppler and Tissue Doppler Imaging

    PubMed Central

    Choi, Jin-Oh; Shin, Mi-Seung; Kim, Mi-Jeong; Jung, Hae Ok; Park, Jeong Rang; Sohn, Il Suk; Kim, Hyungseop; Park, Seong-Mi; Yoo, Nam Jin; Choi, Jung Hyun; Kim, Hyung-Kwan; Cho, Goo-Yeong; Lee, Mi-Rae; Park, Jin-Sun; Shim, Chi Young; Kim, Dae-Hee; Shin, Dae-Hee; Shin, Gil Ja; Shin, Sung Hee; Kim, Kye Hun; Park, Jae-Hyeong; Lee, Sang Yeub; Kim, Woo-Shik

    2016-01-01

    Background Hemodynamic and functional evaluation with Doppler and tissue Doppler study as a part of comprehensive echocardiography is essential but normal reference values have never been reported from Korean normal population especially according to age and sex. Methods Using Normal echOcaRdiographic Measurements in a KoreAn popuLation study subjects, we obtained normal reference values for Doppler and tissue Doppler echocardiography including tricuspid annular velocities according to current guidelines and compared values according to gender and age groups. Results Mitral early diastolic (E) and late diastolic (A) velocity as well as E/A ratio were significantly higher in women compared to those in men. Conversely, mitral peak systolic and late diastolic annular velocity in both septal and lateral mitral annulus were significantly lower in women compared to those in men. However, there were no significant differences in both septal and lateral mitral early diastolic annular (e') velocity between men and women. In both men and women, mitral E velocity and its deceleration time as well as both E/A and E/e' ratio considerably increased with age. There were no significant differences in tricuspid inflow velocities and tricuspid lateral annular velocities between men and women except e' velocity, which was significantly higher in women compared to that in men. However, changes in both tricuspid inflow and lateral annular velocities according to age were similar to those in mitral velocities. Conclusion Since there were significant differences in Doppler and tissue Doppler echocardiographic variables between men and women and changes according to age were even more considerable in both gender groups, normal Doppler echocardiographic values should be differentially applied based on age and sex. PMID:27358707

  13. Phase Control of Group Velocity in a Doppler-Broadened Λ-Type Three-Level System

    NASA Astrophysics Data System (ADS)

    Qiu, Tian-Hui; Xie, Min

    2016-06-01

    We theoretically investigate the phase control role on the group velocity of a weak probe field in a Doppler-broadened Λ-type three-level atomic system with the spontaneously generated coherence effect enhanced by an incoherence pump. We find that the absorption-dispersion of the probe field behaves phase and Doppler broadening-dependent phenomena, and testify that the quite large group index can be realized. The group velocity of the probe field can be switched from subluminal to superluminal or vice versa by modulating the relative phase of the two applied light fields. In contrast to the counterpropagating setting, the copropagating case is more suitable for the purpose considered in this paper due to the effectiveness of Doppler-free.

  14. Intracoronary Doppler: Clinical Application And Future Directions

    NASA Astrophysics Data System (ADS)

    Whitlow, Patrick L.; Raymond, Russell E.; Tuzcu, E. Murat

    1989-08-01

    Because coronary arteriography may underestimate the severity of coronary artery disease, other methods to assess the physiologic significance of a coronary lesion have been sought. Experimental data have confirmed that the ratio of peak flow to resting flow, coronary vasodilator reserve (CVDR), is a quantitative measure of the functional significance of a coronary a stenosis. A 20 MHz pulsed Doppler catheter with a 1 mm outer diameter and an innerlumen for guidewire placement was developed in 1985 and has been used for clinical measurement of CVDR. The technique appears safe, and reliable signals can be obtained in the vast majority of patients studied. Limitations of the technique include possible changes in vessel diameter with delivery of a vasodilator stimulus, possible elevation of baseline flow above normal resting values which would diminish the CVDR, and inability to measure absolute coronary flow. These limitations could be overcome by the development of an intravascular Echo-Doppler device in the future.

  15. Analysis of Doppler measurements of people

    NASA Astrophysics Data System (ADS)

    Tan, Robert; Bender, Robert

    2006-05-01

    With the changing nature of international security it is of interest to the military to use remote sensors to detect and classify people as potential threats. We chose a millimeter wave (MMW) radar as our sensor to collect data on single and small groups of people that were either walking or running to determine how easily they could be detected. This work was done to support the concept of using Ka-band radar to detect people from an airborne platform. Fully-polarimetric Ka-Band radar data was collected of people walking and running at various orientations with respect to the radar. Micro-Doppler analysis reveals Doppler oscillations with time that are characteristic of people at all orientations measured.

  16. Design of a Doppler reflectometer for KSTAR

    SciTech Connect

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

    2014-11-15

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

  17. Determination of cardiac output by Doppler echocardiography.

    PubMed Central

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

    1984-01-01

    Cardiac output determined by Doppler echocardiography was compared with that determined by thermodilution at rest and during dobutamine infusion in 10 patients (group A) and by the Fick method at rest in 11 patients (group B). All patients had angina pectoris without valvular heart disease. Maximum spatial blood velocity and cross sectional aortic area were estimated by the Doppler technique and echocardiography. Cardiac output was calculated by multiplying blood velocity by aortic area at various levels in the ascending aorta. The best correlation of cardiac output between the invasive and non-invasive methods was obtained when maximum velocity in the aortic root and the aortic orifice area were used in the calculations. Cardiac output was considerably overestimated when area measurements in the aortic root were used. Images PMID:6689921

  18. Scrotal inflammatory disease: color Doppler US findings.

    PubMed

    Horstman, W G; Middleton, W D; Melson, G L

    1991-04-01

    A study of 45 patients with 51 cases of hemiscrotal inflammatory disease was done to determine the color Doppler ultrasonographic appearance of scrotal inflammatory disorders. The diagnosis was ultimately established by means of appropriate response to antibiotic treatment (47 cases) or surgery (four cases). In all cases, there was evidence of hyperemia: an increased number and concentration of detectable vessels in the affected portion of the scrotum. In 17 cases, the gray scale images were normal, and the only evidence of inflammation was the presence of hypervascularity. Abnormally decreased epididymal vascular resistance was detected in 14 cases of epididymitis; abnormally decreased testicular vascular resistance was detected in six cases of orchitis. Spontaneous venous flow was present in 18 patients. The authors conclude that color Doppler can demonstrate the hyperemic response to scrotal inflammatory disease and that, in the proper clinical setting, it can supplement the gray scale findings and increase diagnostic confidence.

  19. Doppler-multipath tolerant voice communication

    NASA Astrophysics Data System (ADS)

    Harris, R. M.

    Line of sight communication between high performance aircraft has been found to be subject to a peculiar form of multipath radio wave propagation - Doppler multipath. It degrades analogue voice reception on the standard fit ultrahigh frequency radio, producing low frequency random noise and warbling. Various modifications were carried out on the aircraft's communications system, but the problem remained. All the evidence points to a natural phenomenon. The reported observations are corroborated by theoretical studies and laboratory simulations of multipath radio wave propagation between two points moving relative to a diffusely scattering reflector. Theoretical predictions of Rician fading have explained the disruption of speech transmitted using conventional dsb(am) modulation. This also indicated suppressing the carrier as a radical cure. Double sideband suppressed carrier radios have been developed for airborne evaluation in comparison with standard dsb(am). The air to air flying trials proved the superior performance of the suppressed carrier system under conditions of Doppler multipath.

  20. ROTATIONAL DOPPLER BEAMING IN ECLIPSING BINARIES

    SciTech Connect

    Groot, Paul J.

    2012-01-20

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

  1. [Doppler evaluation of thyroid hemodynamics after intravenous administration of contrast media].

    PubMed

    Catalano, O; Lobianco, R; Maglione, M; Siani, A

    2001-01-01

    Duplex Doppler ultrasound allows the evaluation of thyroid gland vascular flow by spectral analysis assessment. The objective of this prospective study was to employ Doppler ultrasound to evaluate the possible functional changes produced in normal subjects following intravenous iodized contrast medium injection. The study was performed on 30 non-consecutive subjects, enrolled according to some inclusion criteria: male gender, age ranging between 19 and 70 years, absence of chronic liver disease, absence of thyroid disease, absence of sonographic changes in the thyroid gland, negative history for recent intravenous contrast medium administration. All patients were scheduled for a contrast-enhanced CT study. A non-ionic contrast medium (iomeprol) was employed at 350 mgI/mL concentration, 130-140 mL volume, and 2-4 mL/sec. injection rate. The Doppler ultrasound examination was carried out immediately before and about 30 minutes after the CT study. The systolic velocity, diastolic velocity, the resistive index, and the pulsatility index were measured at the level of one of the four thyroid arteries. In most cases a slightly increasing trend of the four parameters considered was noted but none of these showed a statistically significant change. The mean systolic velocity was of 33 cm/sec. in the basal measurement and of 39 cm/sec. in the post-contrast measurement. The variation was positive in 17 cases, negative in 12, and absent in 1. The mean diastolic velocity was of 13 cm/sec. in the pre-contrast evaluation and of 14 cm/sec. in the second evaluation. The change was positive in 14 cases, negative in 12, and absent in 4. The mean resistive index was of 0.55 in the basal analysis and of 0.59 in the post-contrast one. The variation was positive in 20 patients, negative in 9, and absent in 1. The mean pulsatility index was of 0.99 in the basal measurement and of 1.14 in the second measurement. The change was positive in 23 subjects, negative in 5, and absent in 2. Our

  2. Sub miniaturized laser doppler velocimeter sensor

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  3. Doppler Lidar Wind Value-Added Product

    SciTech Connect

    Newsom, R. K.; Sivaraman, C.; Shippert, T. R.; Riihimaki, L. D.

    2015-07-01

    Wind speed and direction, together with pressure, temperature, and relative humidity, are the most fundamental atmospheric state parameters. Accurate measurement of these parameters is crucial for numerical weather prediction. Vertically resolved wind measurements in the atmospheric boundary layer are particularly important for modeling pollutant and aerosol transport. Raw data from a scanning coherent Doppler lidar system can be processed to generate accurate height-resolved measurements of wind speed and direction in the atmospheric boundary layer.

  4. Doppler, Johann Christian Andreas (1803-53)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

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

  5. Doppler-Shifted Raman Spectroscopy Measures Flows

    NASA Technical Reports Server (NTRS)

    Exton, Reginald J.; Hillard, Mervin E., Jr.; Lempert, Walter R.; Covell, Peter F.; Miller, David S.

    1990-01-01

    Technique for measuring velocity, static pressure, and translational temperature of flowing molecules by use of stimulated Raman spectroscopy demonstrated in supersonic wind tunnel at NASA Langley Research Center. Nonintrusive, accurate wind-tunnel measurements obtained without seeding flows. Optical equipment for vibration-free Raman doppler velocimetry in wind tunnel includes specially designed retrometer that reduces sensitivity of system to vibrations. This capability very valuable in aerodynamic testing and proves useful in wide variety of laboratory, industrial, and engineering applications.

  6. Evaluation of the effect of machine settings on quantitative three-dimensional power Doppler angiography: an in-vitro flow phantom experiment.

    PubMed

    Raine-Fenning, N J; Nordin, N M; Ramnarine, K V; Campbell, B K; Clewes, J S; Perkins, A; Johnson, I R

    2008-09-01

    Three-dimensional (3D) ultrasound is being used increasingly to acquire and subsequently quantify power Doppler data within the clinical setting. One proprietary software package calculates three 3D vascular indices: the vascularization index (VI), the flow index (FI), and the vascularization flow index (VFI). Our aim was to evaluate how different settings affect the Doppler signal in terms of its quantification by these three indices within a 3D dataset. A computer-driven 'flow phantom' was used to continuously pump a nylon particle-based blood mimic (Orgasol(trade mark)) around a closed system through a C-flex(trade mark) tube embedded in an agar-based tissue mimic. The test tanks were insonated with a modified 3D transvaginal 4-8-MHz ultrasound transducer (V530D) and power Doppler data were acquired over a series of different settings. Each experiment involved the manipulation of just one Doppler setting in order to study it in isolation. As expected, all of the power Doppler settings, when altered, were found to effect significant changes (P < 0.05) in the VI, FI and VFI. The gain and signal power had the greatest effect, producing no Doppler signals at the lowest settings and the highest recordable indices at the maximum settings. The pulse repetition frequency (PRF) was the next most influential setting but a Doppler signal was seen and measurable at all of the different settings. The other Doppler settings had a much less profound effect on the vascular indices, with subtle but significantly different measures across the full range of settings. The speed of data acquisition was also found to affect the vascular indices, all of which were reduced when the fast mode was used although the only significant effect was on the VFI. The VI, FI and VFI are all affected significantly by variations in power Doppler settings and by the speed of acquisition. The gain and signal power have the greatest effect on the power Doppler signal, followed closely by the PRF. The

  7. Defect Tolerance to Intolerance in the Vacancy-Ordered Double Perovskite Semiconductors Cs 2 SnI 6 and Cs 2 TeI 6

    SciTech Connect

    Maughan, Annalise E.; Ganose, Alex M.; Bordelon, Mitchell M.; Miller, Elisa M.; Scanlon, David O.; Neilson, James R.

    2016-07-13

    Vacancy-ordered double perovskites of the general formula, A2BX6, are a family of perovskite derivatives composed of a face-centered lattice of nearly isolated [BX6] units with A-site cations occupying the cuboctahedral voids. Despite the presence of isolated octahedral units, the close-packed iodide lattice provides significant electronic dispersion, such that Cs2SnI6 has recently been explored for applications in photovoltaic devices. To elucidate the structure-property relationships of these materials, we have synthesized the solid solution Cs2Sn1-xTexI6. However, even though tellurium substitution increases electronic dispersion via closer I-I contact distances, the substitution experimentally yields insulating behavior from a significant decrease in carrier concentration and mobility. Density functional calculations of native defects in Cs2SnI6 reveal that iodine vacancies exhibit a low enthalpy of formation and the defect energy level is a shallow donor to the conduction band, rendering the material tolerant to these defect states. The increased covalency of Te-I bonding renders the formation of iodine vacancy states unfavorable, and is responsible for the reduction in conductivity upon Te substitution. Additionally, Cs2TeI6 is intolerant to the formation of these defects, as the defect level occurs deep within the band gap and thus localizes potential mobile charge carriers. In these vacancy-ordered double perovskites, the close-packed lattice of iodine provides significant electronic dispersion, while the interaction of the B- and X-site ions dictates the properties as they pertain to electronic structure and defect tolerance. This simplified perspective -- based on extensive experimental and theoretical analysis -- provides a platform from which to understand structure-property relationships in functional perovskite halides.

  8. Volumetric Doppler angle correction for ultrahigh-resolution optical coherence Doppler tomography

    NASA Astrophysics Data System (ADS)

    You, Jiang; Li, Ang; Du, Congwu; Pan, Yingtian

    2017-01-01

    Ultrahigh-resolution optical coherence Doppler tomography (μODT) demonstrates great potential for quantitative blood flow imaging owing to its large field of view and capillary resolution. However, μODT only detects the axial flow velocity and requires Doppler angle correction to retrieve the absolute velocity. Although methods for Doppler angle tracking of single or few large vessels have been reported, a method that enables angle correction of the entire 3D microvascular networks remains a challenge. Here, we present a method based on eigenvalue analysis of 3D Hessian matrix to retrieve the orientation of each tubular vessel. As the algorithm is voxel based, it is suitable for effective tracking of Doppler angle matrix and restoring the absolute flow over the 3D vascular flow networks. We present results on simulation and flow phantom studies to show its efficacy for accurate 3D angle tracking and absolute flow correction. Then, we perform an in vivo validation study on mouse micro-circulatory cerebral blood flow (CBF) networks, which clearly demonstrates the capability of this method for tracking the Doppler angle matrix of the highly complex 3D CBF networks.

  9. Laser Doppler systems in pollution monitoring

    NASA Technical Reports Server (NTRS)

    Miller, C. R.; Sonnenschein, C. M.; Herget, W. F.; Huffaker, R. M.

    1976-01-01

    The paper reports on a program undertaken to determine the feasibility of using a laser Doppler velocimeter (LDV) to measure smoke-stack gas exit velocity, particulate concentration, and mass flow. Measurements made with a CO2 laser Doppler radar system at a coal-burning power plant are compared with in-stack measurements made by a pitot tube. The operational principles of a LDV are briefly described along with the system employed in the present study. Data discussed include typical Doppler spectra from smoke-stack effluents at various laser elevation angles, the measured velocity profile across the stack exit, and the LDV-measured exit velocity as a function of the exit velocity measured by the in-stack instrument. The in-stack velocity is found to be about 14% higher than the LDV velocity, but this discrepancy is regarded as a systematic error. In general, linear relationships are observed between the laser data, the exit velocity, and the particulate concentration. It is concluded that an LDV has the capability of determining both the mass concentration and the mass flow from a power-plant smoke stack.

  10. Velocity variability in ultrasonic Doppler examinations.

    PubMed

    Hadlock, Jean; Beach, Kirk W

    2009-06-01

    Ultrasonic Doppler examination with spectral waveform has been used for the classification and surveillance of carotid artery stenosis for over 25 years. Progression/regression between examinations can be identified with 95% confidence if the velocity measurements change by more than two times the root mean square difference (RMSD) of the repeat measurement. Peak systolic velocity and end diastolic velocity measurements at a Doppler angle of 60 degrees were repeated in 47 carotid examinations. Measurement difference between sonographers and between instruments was tabulated. Root mean square difference was 11 cm/s (RMS%D = 11%) for systolic and 7 cm/s (RMS%D = 21%) for diastolic velocity measurements (excluding one severe stenosis case). Results for differences between sonographers and between instruments were similar to the overall results. In serial arterial studies using this Doppler velocimetry method, a difference exceeding 23 cm/s (21%) systolic, or 14 cm/s (42%) diastolic velocity indicates a significant (2 x RMSD) hemodynamic change.

  11. Phase Doppler droplet sizing: Scattering angle effects

    SciTech Connect

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

    1990-01-01

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

  12. [Color Doppler in breast tumor pathology].

    PubMed

    Balu-Maestro, C; Bruneton, J N; Giudicelli, T; Chauvel, C; Hery, M D

    1991-11-01

    Colour Doppler findings in a series of 63 cases of breast tumours and 19 cases of lymph node enlargements are reported. Colour Doppler signals of abnormal flow are found in 68.5 percent of the cancers, in 42.8 percent of metastatic lymph nodes and in 10 percent of benign lesions. There was bidirectional flow in 80 percent of all the cases. In cases of malignant tumours, the signal was correlated with the size and location of the lesions most often found peripherally. Presently, this technique appears to be of little value in determining whether a primary malignant tumour of the breast is malignant or benign. It does appear to be useful, first to follow-up cancers during initial chemotherapy (partial regression of the signal and of tumour volume) and secondly, in the diagnosis of metastatic lymph nodes with a specificity of 100 percent in our series. Colour Doppler is on the contrary difficult to interprete after conservative treatment of breast cancer because of post-radiotherapy tissue remodelling.

  13. Doppler Lidar for Wind Measurements on Venus

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  14. Laser Doppler measurement techniques for spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.; Gagliardi, Robert M.

    1986-01-01

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

  15. Audio spectrum analysis of umbilical artery Doppler ultrasound signals applied to a clinical material.

    PubMed

    Thuring, Ann; Brännström, K Jonas; Jansson, Tomas; Maršál, Karel

    2014-12-01

    Analysis of umbilical artery flow velocity waveforms characterized by pulsatility index (PI) is used to evaluate fetoplacental circulation in high-risk pregnancies. However, an experienced sonographer may be able to further differentiate between various timbres of Doppler audio signals. Recently, we have developed a method for objective audio signal characterization; the method has been tested in an animal model. In the present pilot study, the method was for the first time applied to human pregnancies. Doppler umbilical artery velocimetry was performed in 13 preterm fetuses before and after two doses of 12 mg betamethasone. The auditory measure defined by the frequency band where the spectral energy had dropped 15 dB from its maximum level (MAXpeak-15 dB ), increased two days after betamethasone administration (p = 0.001) parallel with a less pronounced decrease in PI (p = 0.04). The new auditory parameter MAXpeak-15 dB reflected the changes more sensitively than the PI did.

  16. [Transfontanellar Doppler ultrasound measurement of cerebral blood velocity before and after surgical treatment of hydrocephalus].

    PubMed

    de Assis, M C; Machado, H R

    1999-09-01

    Twenty-seven children with hydrocephalus of different etiologies diagnosed by clinical examination, neurosonography and computerized brain tomography were submitted to transfontanellar US-Doppler evaluation for measurement of blood flow velocity and for the calculation of resistance index (RI) in the anterior and middle cerebral arteries and internal carotids. All children were submitted to evaluation before surgery and on the 1st, 30th and 60th postoperative days. We conclude that neurosonography and US-Doppler technique is useful for determination of hydrocephalus, indication and control of cerebrospinal fluid shunts and monitoring of changes in RI, comparing data obtained immediately before and after surgery and during the late postoperative period. The results obtained when comparing the RI values for the various arteries during the different stages of the study also permitted us to conclude that the anterior cerebral arteries are representative of the maximal alterations that occur in cerebral vascular resistance in pediatric patients with hydrocephalus.

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

    PubMed Central

    Thuring, Ann; Brännström, K. Jonas; Ewerlöf, Maria; Hernandez-Andrade, Edgar; Ley, David; Lingman, Göran; Liuba, Karina; Maršál, Karel; Jansson, Tomas

    2013-01-01

    Objective An experienced sonographer can by listening to the Doppler audio signals perceive various timbres that distinguish different types of umbilical artery flow despite an unchanged pulsatility index (PI). Our aim was to develop an objective measure of the Doppler audio signals recorded from fetoplacental circulation in a sheep model. Methods Various degrees of pathological flow velocity waveforms in the umbilical artery, similar to those in human complicated pregnancies, were induced by microsphere embolization of the placental bed (embolization model, 7 lamb fetuses, 370 Doppler recordings) or by fetal hemodilution (anemia model, 4 lamb fetuses, 184 recordings). A subjective 11-step operator auditory scale (OAS) was related to conventional Doppler parameters, PI and time average mean velocity (TAM), and to sound frequency analysis of Doppler signals (sound frequency with the maximum energy content [MAXpeak] and frequency band at maximum level minus 15 dB [MAXpeak-15 dB] over several heart cycles). Results We found a negative correlation between the OAS and PI: median Rho −0.73 (range −0.35– −0.94) and −0.68 (range −0.57– −0.78) in the two lamb models, respectively. There was a positive correlation between OAS and TAM in both models: median Rho 0.80 (range 0.58–0.95) and 0.90 (range 0.78–0.95), respectively. A strong correlation was found between TAM and the results of sound spectrum analysis; in the embolization model the median r was 0.91 (range 0.88–0.97) for MAXpeak and 0.91 (range 0.82–0.98) for MAXpeak-15 dB. In the anemia model, the corresponding values were 0.92 (range 0.78–0.96) and 0.96 (range 0.89–0.98), respectively. Conclusion Audio-spectrum analysis reflects the subjective perception of Doppler sound signals in the umbilical artery and has a strong correlation to TAM-velocity. This information might be of importance for clinical management of complicated pregnancies as an addition to conventional Doppler parameters

  18. Effect of Betamethasone on Fetal Pulmonary and Umbilical Artery Doppler Velocimetry and Relationship With Respiratory Distress Syndrome Development.

    PubMed

    Güngör, Emre Sinan; İlhan, Gülşah; Gültekin, Hüseyin; Zebitay, Ali Galip; Cömert, Serdar; Verit, Fatma Ferda

    2017-06-19

    Respiratory distress syndrome (RDS) is a major cause of neonatal morbidity and mortality. It is primarily a disease of premature neonates. The aim of this study was to evaluate the impact of maternal betamethasone administration on the fetal pulmonary arteries (PAs) and umbilical arteries (UAs) and the correlation between RDS development and PA Doppler results. Forty singleton pregnancies between 24 and 34 gestational weeks with a diagnosis of preterm birth were included prospectively. They received corticosteroids to enhance fetal lung maturity. Fetal PA and UA Doppler parameters were evaluated before and 48 to 72 hours after steroid administration. Maternal records were matched to neonatal charts, and demographic and outcome data were abstracted. There were no differences between groups for maternal age, body mass index, mode of delivery, and mean GA at steroid administration. Apgar scores at 1 and 5 minutes were significantly lower for neonates who developed RDS (P < .05). There were no statistically significant differences in PA Doppler results between fetuses who developed RDS and those who did not, and there were no significant differences in PA Doppler results before and after steroid administration for both groups. The UA pulsatility and resistive indices were significantly lower after steroid administration for the neonates who developed RDS (P < .05). There were no significant differences in PA Doppler indices for fetuses with or without RDS after steroid administration. © 2017 by the American Institute of Ultrasound in Medicine.

  19. Analysis and improved design considerations for airborne pulse Doppler radar signal processing in the detection of hazardous windshear

    NASA Technical Reports Server (NTRS)

    Lee, Jonggil

    1990-01-01

    High resolution windspeed profile measurements are needed to provide reliable detection of hazardous low altitude windshear with an airborne pulse Doppler radar. The system phase noise in a Doppler weather radar may degrade the spectrum moment estimation quality and the clutter cancellation capability which are important in windshear detection. Also the bias due to weather return Doppler spectrum skewness may cause large errors in pulse pair spectral parameter estimates. These effects are analyzed for the improvement of an airborne Doppler weather radar signal processing design. A method is presented for the direct measurement of windspeed gradient using low pulse repetition frequency (PRF) radar. This spatial gradient is essential in obtaining the windshear hazard index. As an alternative, the modified Prony method is suggested as a spectrum mode estimator for both the clutter and weather signal. Estimation of Doppler spectrum modes may provide the desired windshear hazard information without the need of any preliminary processing requirement such as clutter filtering. The results obtained by processing a NASA simulation model output support consideration of mode identification as one component of a windshear detection algorithm.

  20. Impact of Overweight and Obesity on Left Ventricular Diastolic Function and Value of Tissue Doppler Echocardiography

    PubMed Central

    Kossaify, Antoine; Nicolas, Nayla

    2013-01-01

    Background Diastolic dysfunction is a common cause of heart failure with preserved systolic function in obese patients. Objective To assess diastolic function in a series of overweight and obese patients using conventional and tissue Doppler echocardiography. Setting and method University hospital; left ventricular diastolic function was evaluated in 99 patients (mean age 61.59 ± 13.9 years); body mass index and waist circumference were assessed, and patients were subdivided into three groups according to their body mass index (kg/m2): [normal, (18.5–24.9); overweight, (25–29.9); obese, (>29.9)]. Peak early (E) and late (A) transmitral flow and peak early (E′) diastolic mitral annulus velocities were measured. Results Diastolic dysfunction was significantly higher in the overweight/obese groups compared to the normal body mass index group. The analysis was made with regard to waist circumference and other clinical characteristics, and multivariate regression analysis showed a direct and independent effect of body mass index on diastolic function [OR: 2.75; CI: 1.34–5.67; P = 0.006]. Discussion was made in view of the latest clinical data. Also, an insight into normal weight obesity is presented and discussed. Conclusion Overweight and obesity are found to have an independent negative impact on diastolic function as assessed by tissue Doppler imaging. PMID:23471126

  1. Doppler study and evidences of perfusion changes in the ophthalmic artery of pregnant smokers.

    PubMed

    Paes, Maria Marta Bini Martins; Diniz, Angélica Lemos Debs; Jorge, Ana Paula Lino

    2013-12-01

    To compare the ophthalmic artery (OA) perfusion of pregnant smokers and nonsmokers by Doppler indexes. Correlate these with the interval of last cigarette, cigarettes per day, years smoking and carbon monoxide expired (COex). Transversal study involving 70 pregnant smokers divided into 33 pregnant who smoked until 2 h: A group (AG) and B group (BG): 37, who smoked between 2 and 24 h before test. Control group (CG) was composed of 51 pregnant nonsmokers. Doppler indexes were assessed: PSV (Peak Systolic Velocity), EDV (End Diastolic Velocity), PI (Pulsatility Index), RI (Resistance Index) and PR (Peak Ratio). Groups were compared using ANOVA, Kruskal-Wallis test, Student's t test, Mann-Whitney and Pearson's correlation coefficient, whereas p < 0.05. RI and PI were higher (p < 0.01) and PSV and EDV were lower (p < 0.05) in B group compared to other groups. A group presented higher PR (p < 0.01) compared to control. AG presented years of smoking, cigarettes per day, COex greater than BG and lower interval of last cigarette than BG. The OA in pregnant smokers shows a biphasic pattern of perfusion correlated with the time of consumption of the last cigarette. There are signs of vasoconstriction and hypoperfusion to tobacco exposure between 2 and 24 and hyperperfusion in A Group compared to B Group.

  2. Diagnosis of Placenta Accreta by Uterine Artery Doppler Velocimetry in Patients With Placenta Previa.

    PubMed

    Cho, Hee Young; Hwang, Han Sung; Jung, Inkyung; Park, Yong Won; Kwon, Ja-Young; Kim, Young Han

    2015-09-01

    To evaluate the potential value of uterine artery Doppler velocimetry in diagnosing placenta accreta. Clinical records of all deliveries between April 1991 and March 2013 were retrospectively analyzed. Cases of intrauterine growth restriction, pregnancy-induced hypertension, multiple pregnancies, fetal anomalies, chromosomal abnormalities, and maternal medical illnesses such as cardiovascular disease, renal disease, and diabetes mellitus were excluded. A total of 11,210 cases were evaluated, including 403 cases of placenta previa without accreta (placenta previa) and 39 cases of placenta previa with accreta (placenta accreta). All patients underwent uterine artery Doppler velocimetry to measure the mean resistive index and pulsatility index (PI) in the third trimester. The analysis included participant characteristics such as age, parity, abortion history, previous cesarean delivery, gestational age at delivery, neonatal sex, and birth weight. The mean uterine artery PI was significantly lower in the placenta accreta group compared to previa alone (0.51 versus 0.57; P = .002). The odds ratios for placenta accreta were 2.4 for 2 or more previous abortions (P = .011) and 5.3 and 7.0 for 1 and 2 or more previous cesarean deliveries (P = .001 and .005). With an increase in the mean PI by 0.01, the odds ratio for placenta accreta decreased by 0.94 (P < .001). The area under the receive operating characteristic curve was 0.72 for previous cesarean delivery alone, increasing to 0.77 with the combination of the mean PI and previous cesarean delivery (P = .047). This study suggests that the mean PI measured by uterine artery Doppler velocimetry is reduced in patients with placenta accreta compared to those without accreta. The diagnostic accuracy of placenta accreta can be potentially improved if uterine artery Doppler values and the history of cesarean delivery are combined. © 2015 by the American Institute of Ultrasound in Medicine.

  3. Ultrasound safety in early pregnancy: reduced energy setting does not compromise obstetric Doppler measurements.

    PubMed

    Sande, R K; Matre, K; Eide, G E; Kiserud, T

    2012-04-01

    We hypothesized that first-trimester Doppler ultrasonography can be carried out at lower output energies than the currently advocated limits without compromising clinically important information. We recruited 42 pregnant women for an ultrasound examination at 12 weeks' gestation. Twenty-one women were examined with a transvaginal transducer, the rest with a transabdominal transducer. We used pulsed Doppler to measure pulsatility index (PI) and peak systolic velocity (PSV) in five clinically relevant fetal and maternal blood vessels. The energy indicator thermal index for bone (TIb) was set at 1.0, 0.5 and 0.1. Each measurement was repeated three times. A mixed linear regression model accounting for correlation between measurements was used to assess the effect of different TIb levels and transducers. We were able to visualize the vessels by color Doppler and measure PI and PSV in all vessels at all energy levels in all the participants with the exception of the ductus venosus in two participants, yielding 1872 recordings for statistical analysis. A reduction in TIb from 1.0 to 0.5 and 0.1 had no effect on the PI or PSV values, nor was there any trend towards higher parameter variance with decreasing TIb. There was no difference between measured values of PI and PSV between the transducers, but the transabdominal technique was associated with a greater parameter variance. Reliable first-trimester Doppler data can be obtained with output energy reduced to a TIb of 0.5 or 0.1. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

  4. The characteristics of solid etalon Doppler discriminator and transmitter in designing Doppler lidar

    NASA Astrophysics Data System (ADS)

    Kim, Dukhyeon; Cheong, Hae-Du

    2012-11-01

    In this paper, we propose a new type of Doppler discrimination system using an unseeded pulsed Q-switched laser and solid etalon. To substantiate our system, we calculate the transmitting spectral power distribution and discriminator characteristics. In our calculation, we use a 25 mm thick solid etalon with a finesse of 30, as well as a normal pulsed laser with a bandwidth of 1 cm-1. The results reveal that the change in the receiving scattered signal through the discriminator with a given LOS(Line of Sight) wind velocity is more sensitive than a normal iodine metal vapor-based Doppler lidar receiving system. We experimentally verify our suggestion using our Doppler discriminator and transmitter, and confirm that this combination is more sensitive than a metal vapor filter. Moreover, we suggest a more efficient transmitter and a more sensitive double-edge receiving system based on our calculations and experimental results.

  5. Direct measurement of Lorentz transformation with Doppler effects

    NASA Astrophysics Data System (ADS)

    Chen, Shao-Guang

    For space science and astronomy the fundamentality of one-way velocity of light (OWVL) is selfevident. The measurement of OWVL (distance/interval) and the clock synchronization with light-signal transfer make a logical circulation. This means that OWVL could not be directly measured but only come indirectly from astronomical method (Romer's Io eclipse and Bradley's sidereal aberration), furthermore, the light-year by definitional OWVL and the trigonometry distance with AU are also un-measurable. For to solve this problem two methods of clock synchronization were proposed: The direct method is that at one end of dual-speed transmissionline with single clock measure the arriving-time difference of longitudinal wave and transverse wave or ordinary light and extraordinary light, again to calculate the collective sending-time of two wave with Yang's /shear elastic-modulus ratio (E/k) or extraordinary/ordinary light refractive-index ratio (ne/no), which work as one earthquake-station with single clock measures first-shake time and the distance to epicenter; The indirect method is that the one-way wavelength l is measured by dual-counters Ca and Cb and computer's real-time operation of reading difference (Nb - Na) of two counters, the frequency f is also simultaneously measured, then l f is just OWVL. Therefore, with classical Newtonian mechanics and ether wave optics, OWVL can be measured in the Galileo coordinate system with an isotropic length unit (1889 international meter definition). Without any hypotheses special relativity can entirely establish on the metrical results. When a certain wavelength l is defined as length unit, foregoing measurement of one-way wavelength l will become as the measurement of rod's length. Let a rigidity-rod connecting Ca and Cb moves relative to lamp-house with velocity v, rod's length L = (Nb - Na) l will change follow v by known Doppler effect, i.e., L(q) =L0 (1+ (v/c) cos q), where L0 is the proper length when v= 0, v• r = v cos q

  6. Hepatic flow parameters measured with MR imaging and Doppler US: correlations with degree of cirrhosis and portal hypertension.

    PubMed

    Annet, Laurence; Materne, Roland; Danse, Etienne; Jamart, Jacques; Horsmans, Yves; Van Beers, Bernard E

    2003-11-01

    To determine the correlations between hemodynamic parameters of hepatic flow measured with magnetic resonance (MR) imaging and Doppler ultrasonography (US) and the severity of cirrhosis and portal hypertension. Forty-six patients referred for measurements of portal venous pressure (three with normal liver, 12 with chronic hepatitis, and 31 with cirrhosis [10 with Child-Pugh class A cirrhosis; 13 with class B cirrhosis; and eight with class C cirrhosis]) were included in the study. Apparent liver perfusion, apparent arterial and portal perfusion, portal fraction, distribution volume, and mean transit time were measured with dynamic contrast material-enhanced MR imaging. Portal velocity, portal flow, congestion index, right hepatic artery resistance index, and modified hepatic index were measured with Doppler US. Results in patients with cirrhosis and those without cirrhosis were compared with the Wilcoxon rank sum test. Correlations were assessed with Spearman rank correlation coefficients. With MR imaging, all flow parameters except distribution volume were significantly different between patients with and those without cirrhosis (P <.05). There was a significant correlation between all flow parameters measured with MR imaging and portal pressure (P <.02). Apparent arterial (P =.024) and portal (P <.001) perfusion, portal fraction (P <.001), and mean transit time (P =.004) were correlated with Child-Pugh class. Flow parameters measured with Doppler US did not differ significantly between patients with and those without cirrhosis. Only right hepatic arterial resistance (P <.007) and portal flow (P <.043) were weakly (r < 0.7) correlated with portal pressure. No Doppler US parameter was correlated with Child-Pugh class. Hepatic flow parameters measured with MR imaging correlate with the severity of cirrhosis and portal hypertension. Doppler US parameters are only weakly correlated with portal pressure. Copyright RSNA, 2003

  7. Doppler and speckle methods for diagnostics in dentistry

    NASA Astrophysics Data System (ADS)

    Ulyanov, Sergey S.; Lepilin, Alexander V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Kharish, Natalia A.; Osipova, Yulia; Karpovich, Alexander

    2002-02-01

    The results of statistical analysis of Doppler spectra of scattered intensity, obtained from tissues of oral cavity membrane of healthy volunteers, are presented. The dependence of the spectral moments of Doppler signal on cutoff frequency is investigated. Some results of statistical analysis of Doppler spectra, obtained from tooth pulp of patients, are presented. New approach for monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of measuring system on formation of speckle-interferometric signal is studied.

  8. Applications of Doppler ultrasound in clinical vascular disease

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  9. Applications of Doppler ultrasound in clinical vascular disease

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  10. Reexamination of the Doppler effect through Maxwell's equations.

    PubMed

    Guo, Wei; Aktas, Yildirim

    2012-08-01

    In this work, the electric field emitted from a moving source, an electric point dipole, is analyzed for the purpose of illustrating the physics behind the Doppler effect. It is found that if the (translational) motion of the source is nonrelativistic, the Doppler effect is realized in two steps: the motion of the source first causes the dyadic Green function associated with the electric field to acquire an oscillation frequency in the far-field region of the source, and then the frequency leads to the Doppler effect. It is also demonstrated that the Doppler effect is observable only in the far-field region of the source.

  11. Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors

    NASA Technical Reports Server (NTRS)

    Constantindes, N. J.; Bicknell, T. J.

    1984-01-01

    Pair of photodetectors generates correction signals. Instrument detects Doppler shifts in radar and corrects processing parameters so ambiguities caused by shifts not manifested as double or overlapping images.

  12. Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors

    NASA Technical Reports Server (NTRS)

    Constantindes, N. J.; Bicknell, T. J.

    1984-01-01

    Pair of photodetectors generates correction signals. Instrument detects Doppler shifts in radar and corrects processing parameters so ambiguities caused by shifts not manifested as double or overlapping images.

  13. Christian Doppler is 200 years young.

    PubMed

    Bollinger, Alfred; Partsch, Hugo

    2003-11-01

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

  14. PRECISE DOPPLER MONITORING OF BARNARD'S STAR

    SciTech Connect

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

    2013-02-20

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

  15. The feasibility of Doppler monitoring during EVA

    NASA Astrophysics Data System (ADS)

    Barer, A.; Filipenkov, S.; Katuntsev, V.; Vogt, L.; Wenzel, J.

    1995-07-01

    During extravehicular activities (EVA) outside the spacecraft, astronauts have to work under reduced pressure in a space suit. This pressure reduction induces the risk of decompression sickness (DCS) by the formation of gas bubbles from excess nitrogen dissolved in the organism by breathing air at normal pressure. Under laboratory conditions the gas bubbles moving in the blood stream can be detected by the non-invasive ultrasonic Doppler method. By early detection of excessive bubble formation the development of DCS symptoms may be prevented by early application of preventative measures. The method could also be useful when applied in the space suit in order to compare the results of laboratory tests with operational results, because there is a discrepancy according to the DCS risk of laboratory experiments and actual EVA missions, where no symptoms have been reported yet. A prototype Doppler sensor has been developed and implemented in the Russian Orlan suit. To investigate the feasibility of this method under simulated space conditions, the equipment has been used in a series of 12 thermovacuum chamber tests with suited subjects, where intravenous bubble formation was compared to unsuited control experiments. In more than 50% of the suited tests good Doppler recordings could be achieved. In some cases with unsatisfying results the signal could be improved by breathholding. Although the results do not yet allow any conclusion about a possible difference between suited and unsuited subjects due to the small number of tests performed, the method proved its feasibility for use in EVA suits and should be further developed to enhance the safety of EVA procedures.

  16. The feasibility of Doppler monitoring during EVA.

    PubMed

    Barer, A; Filipenkov, S; Katuntsev, V; Vogt, L; Wenzel, J

    1995-07-01

    During extravehicular activities (EVA) outside the spacecraft, astronauts have to work under reduced pressure in a space suit. This pressure reduction induces the risk of decompression sickness (DCS) by the formation of gas bubbles from excess nitrogen dissolved in the organism by breathing air at normal pressure. Under laboratory conditions the gas bubbles moving in the blood stream can be detected by the non-invasive ultrasonic Doppler method. By early detection of excessive bubble formation the development of DCS symptoms may be prevented by early application of preventative measures. The method could also be useful when applied in the space suit in order to compare the results of laboratory tests with operational results, because there is a discrepancy according to the DCS risk of laboratory experiments and actual EVA missions, where no symptoms have been reported yet. A prototype Doppler sensor has been developed and implemented in the Russian Orlan suit. To investigate the feasibility of this method under simulated space conditions, the equipment has been used in a series of 12 thermovacuum chamber tests with suited subjects, where intravenous bubble formation was compared to unsuited control experiments. In more than 50% of the suited tests good Doppler recordings could be achieved. In some cases with unsatisfying results the signal could be improved by breathholding. Although the results do not yet allow any conclusion about a possible difference between suited and unsuited subjects due to the small number of tests performed, the method proved its feasibility for use in EVA suits and should be further developed to enhance the safety of EVA procedures.

  17. [Aortic flow measurement by transesophageal Doppler effect].

    PubMed

    Cathignol, D; Lavandier, B; Muchada, R

    1985-01-01

    Continuous measurement of cardiac output by thermodilution is invasive, impractical and unpleasant for the patient. We propose to measure descending aortic blood flow with a specially designed intra-oesophageal Doppler echo probe. The apparatus is composed of two main parts. First an A scan system makes possible the measurement of the diameter of the vessel, second a continuous wave velocimeter is used to measure the spatial mean velocity of the blood. An output calculator determines the descending aortic blood flow. The oesophageal catheter contains three ultrasonic transducers at its tip mounted on an epoxy resin bracket produced by moulding. They are connected to a flexible hose placed inside a flexible polyvinyl sheath whose outer diameter is 6.8 mm and length is 50 cm. A cylindrical latex balloon is mounted on this sheath which is water inflated to minimum pressure, ensuring a good ultrasonic coupling between the transducers and the oesophageal wall. Connection between the probe and the apparatus is made by three coaxial cables. Three isolator-transformers are built into the connector cable to ensure a safe electrical circuit. After having bled the probe of any air, the balloon is deflated. The probe is gently introduced into the oesophagus by nasal or oral route until the transducers are situated between the 5th and 6th vertebra. The balloon is then inflated to minimum pressure with 10 ml of distilled water contained in a syringe. To find the aorta, the velocimeter is first used like a Doppler stethoscope. The probe is rotated into a position corresponding to the maximum level of Doppler signal.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Current-induced spin wave Doppler shift

    NASA Astrophysics Data System (ADS)

    Bailleul, Matthieu

    2010-03-01

    In metal ferromagnets -namely Fe, Co and Ni and their alloys- magnetism and electrical transport are strongly entangled (itinerant magnetism). This results in a number of properties such as the tunnel and giant magnetoresistance (i.e. the dependence of the electrical resistance on the magnetic state) and the more recently addressed spin transfer (i.e. the ability to manipulate the magnetic state with the help of an electrical current). The spin waves, being the low-energy elementary excitations of any ferromagnet, also exist in itinerant magnets, but they are expected to exhibit some peculiar properties due the itinerant character of the carriers. Accessing these specific properties experimentally could shed a new light on the microscopic mechanism governing itinerant magnetism, which -in turn- could help in optimizing material properties for spintronics applications. As a simple example of these specific properties, it was predicted theoretically that forcing a DC current through a ferromagnetic metal should induce a shift of the frequency of the spin waves [1,2]. This shift can be identified to a Doppler shift undergone by the electron system when it is put in motion by the electrical current. We will show how detailed spin wave measurements allow one to access this current-induced Doppler shift [3]. From an experimental point of view, we will discuss the peculiarities of propagating spin wave spectroscopy experiments carried out at a sub-micrometer length-scale and with MHz frequency resolution. Then, we will discuss the measured value of the Doppler shift in the context of both the old two-current model of spin-polarized transport and the more recent model of adiabatic spin transfer torque. [4pt] [1] P.Lederer and D.L. Mills, Phys.Rev. 148, 542 (1966).[0pt] [2] J. Fernandez-Rossier et al., Phys. Rev. B 69, 174412 (2004)[0pt] [3] V. Vlaminck and M. Bailleul, Science 322, 410 (2008).

  19. Precise Doppler Monitoring of Barnard's Star

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  20. Perinatal outcome and placental apoptosis in patients with late-onset pre-eclampsia and abnormal uterine artery Doppler at diagnosis.

    PubMed

    Rodríguez, Marcelo; Couve-Pérez, Constanza; San Martín, Sebastián; Martínez, Felipe; Lozano, Carlo; Sepúlveda-Martínez, Alvaro

    2017-04-28

    To determine the rate of placental apoptosis and adverse perinatal outcome in patients with late pre-eclampsia and altered uterine artery (UtA) Doppler. A cohort study was performed. Patients with a diagnosis of late pre-eclampsia (l-PE) were stratified according to the UtA Doppler status at diagnosis (below or above the 95(th) percentile). A logistic regression analysis was performed to identify the association between an abnormal UtA Doppler and the presence of adverse maternal and perinatal outcomes. In a subset of this cohort, an immunohistochemical analysis of the placenta was performed to identify the rate of apoptosis and the association with the UtA Doppler against normotensive controls. A non-parametric linear trend analysis was performed for the assessment of the apoptosis index. Eighty-six patients were included in the final analysis. The UtA Doppler was above the 95(th) percentile in 33 (38.4%) patients. Interestingly, the gestational age at diagnosis and delivery were significantly lower in this group compared to the patients with a normal UtA Doppler. An abnormal UtA Doppler was associated with an increased risk of severe PE (OR= 7.5; 95% CI 2.76 - 20.46; p < 0.001), late preterm delivery (OR= 13.7; 95% CI 4.53 - 41.46; p < 0.001), SGA at birth (OR= 12.3; 95% CI 3.17 - 47.57; p < 0.001), and admission to the NICU (OR= 12.8; 95% CI 2.61 - 62.36; p = 0.002). Moreover, the UtA z-score demonstrated a significant inverse correlation with the birth weight z-score (r = -0.34; p = 0.0013). The mean caspase index in the placenta demonstrated an ascending linear trend according to the UtA Doppler assessment (p = 0.04). In patients with l-PE, the UtA Doppler was useful not only for the clinical classification but also for the placental histological findings. The correlation between the UtA Doppler and the apoptosis index provides new evidence of a sub-group of l-PE patients with a placental origin of the disease. This article is

  1. Applications of Doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Xu, Zhiqiang

    A major development in biomedical imaging in the last decade has been optical coherence tomography (OCT). This technique enables microscale resolution, depth resolved imaging of the detailed morphology of transparent and nontransparent biological tissue in a noncontact and quasi-noninvasive way. In the first part of this dissertation, we will describe the development and the performance of our home-made OCT systems working with different wavelength regions based on free-space and optical fiber Michelson interferometers. The second part will focus on Doppler OCT (DOCT), an important extension of OCT, which enables the simultaneous evaluation of the structural information and of the fluid flow distribution at a localized position beneath the sample surface. Much effort has been spent during the past few years in our laboratory aimed at providing more accurate velocity measurements with an extended dynamic range. We also applied our technique in different research areas such as microfluidics and hemodynamics. Investigations on the optical properties of the biological tissues (such as absorption and scattering) corresponding to different center wavelengths, have been performed in our laboratory. We used a 10 femtosecond Ti:sapphire laser centered at about 810 nm associated with a free-space Michelson interferometer. The infrared sources were centered at about 1310 and 1560 nm with all-fiber interferometers. Comparative studies using three different sources for several in vitro biological tissues based on a graphical method illustrated how the optical properties affect the quality of the OCT images in terms of the penetration depth and backscattering intensity. We have shown the advantage of working with 810-nm emission wavelength for good backscattering amplitude and contrast, while sources emitting at 1570 nm give good penetration depth. The 1330-nm sources provide a good compromise between the two. Therefore, the choice of the source will ultimately determine the

  2. Overview of mesocale research Doppler lidar activities

    NASA Technical Reports Server (NTRS)

    Fitzjarrald, D. E.

    1984-01-01

    In evaluating the performance of the airborne Doppler lidar system, a large number of deficiencies or mistakes were identified in the original system and experiment plans. All of the known problems were addressed and corrected in the planning and engineering for the fall 1984/spring 1985 ADLS flight series. Thus, the most significant result of the data analysis was the input it has provided to the preparations for the new experiment. Attitude measurements are taken together with the streamlined operating procedures, color graphics real time displays of data, and better experiment design, the result is a second-generation system that is considerably better than the one used in 1981.

  3. Transmission media effects on precise Doppler tracking

    NASA Technical Reports Server (NTRS)

    Callahan, P. S.

    1978-01-01

    The effects of the transmission media - the earth's troposphere and ionosphere, and the solar wind - on precise Doppler tracking are discussed. The charged particle effects can be largely removed by dual frequency observations; however there are limitations to these corrections (besides system noise and/or finite integration times) including the effects of magnetic fields, diffraction, and differential refraction, all of which must be carefully evaluated. The earth's troposphere can contribute an error of delta f/f approximately 10 to the minus 14th power.

  4. In-suit Doppler technology assessment

    NASA Astrophysics Data System (ADS)

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

    1991-12-01

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

  5. Mobile fiber-optic laser Doppler anemometer.

    PubMed

    Stieglmeier, M; Tropea, C

    1992-07-20

    A laser Doppler anemometer (LDA) has been developed that combines the compactness and low power consumption of laser diodes and avalanche photodiodes with the flexibility and possibility of miniaturization by using fiber-optic probes. The system has been named DFLDA for laser diode fiber LDA and is especially suited for mobile applications, for example, in trains, airplanes, or automobiles. Optimization considerations of fiber-optic probes are put forward and several probe examples are described in detail. Measurement results from three typical applications are given to illustrate the use of the DFLDA. Finally, a number of future configurations of the DFLDA concept are discussed.

  6. Wideband infrared receiver backend. [Doppler radar, radiometers

    NASA Technical Reports Server (NTRS)

    Flattau, T.; Mellars, J.

    1974-01-01

    The design, operation, and configuration of the receiver backend for a wideband infrared tracking receiver are described. A squaring loop is incorporated into the receiver design to enable it to track the Doppler shifted carrier which is Phase Shift Keyed modulated. The receiver has a 400 MHz instantaneous bandwidth and tracks signals whose carrier frequency at the backend input is between 200 and 900 MHz with frequency variation rates greater than 20 MHz/second. The output data is compatible with MECL 3 logic.

  7. Doppler Measurements of the Suns Meridional Flow

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.

    1996-01-01

    Doppler velocity data obtained with the Global Oscillation Network Group (GONG) instruments in Tucson from 1992 August through 1995 April were analyzed to determine the structure and evolution of the Sun's meridional flow. Individual measurements of the flow were derived from line-of-sight velocity images averaged over 17 minutes to remove the p-mode oscillation signal. Typical flow velocities are poleward at approximately 20 m/s, but the results suggest that episodes may occur with much stronger flows. Such variations may help to explain some of the many disparate reports on the strength and structure of the Sun's meridional flow.

  8. The new Adelaide medium frequency Doppler radar

    NASA Astrophysics Data System (ADS)

    Reid, I. M.; Vandepeer, B. G. W.; Dillon, S.; Fuller, B.

    1993-08-01

    The Buckland Park Aerial Array (35 deg S, 138 deg E) is situated about 40 km north of Adelaide on a flat coastal plain. It was designed by Basil Briggs and Graham Elford, and constructed between 1965 and 1968. The first results were published in the late 1960's. Some aspects of the history of the array are described in Briggs (1993). A new MF Doppler Radar utilizing the array has been developed. This paper describes some of the technical details of this new facility.

  9. Signal broadening in the laser Doppler velocimeter.

    NASA Technical Reports Server (NTRS)

    Angus, J. C.; Edwards, R. V.; Dunning, J. W., Jr.

    1971-01-01

    Critical review of a recent paper in which Denison, Stevenson, and Fox (1971) discussed the sources of spectral broadening in the laser Doppler velocimeter. It is pointed out that, in their discussion, the above-mentioned authors indicated that the spread in wave vectors of the incident and detected fields and the finite length of time a scattering center stayed in the sample volume each contributed separately and independently to the observed spectral width of the scattered radiation. This statement is termed incorrect, and it is shown that the two effects are one and the same.

  10. Applying Zeeman Doppler imaging to solar spectra

    NASA Astrophysics Data System (ADS)

    Hussain, G. A. J.; Saar, S. H.; Collier Cameron, A.

    2004-03-01

    A new generation of spectro-polarimeters with high throughput (e.g. CFHT/ESPADONS and LBT/PEPSI) is becoming available. This opportunity can be exploited using Zeeman Doppler imaging (ZDI), a technique that inverts time-series of Stokes V spectra to map stellar surface magnetic fields (Semel 1989). ZDI is assisted by ``Least squares deconvolution'' (LSD), which sums up the signal from 1000's of photospheric lines to produce a mean deconvolved profile with higher S:N (Donati & Collier Cameron 1997).

  11. Catadioptric optics for laser Doppler velocimeter applications

    NASA Technical Reports Server (NTRS)

    Dunagan, Stephen E.

    1989-01-01

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

  12. Dealiasing Doppler velocites using edge detection

    NASA Astrophysics Data System (ADS)

    Meech, Scott P.

    This study presents a new algorithm to dealias folded Doppler velocities in S, C, and X-Band radars using a new boundary detection technique on the raw velocity field as a whole, rather than the traditional gate by gate methodology used in more popular and widespread algorithms. Several different types of precipitation events are used to compare and contrast the final output of the new boundary based algorithm. The results are then compared to the NEXRAD dealiasing algorithm as defined by Eilts and Smith (1989) and an objective manual unfolding by radar manipulation software called SoloII.

  13. In-suit Doppler technology assessment

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  14. Catadioptric optics for laser Doppler velocimeter applications

    NASA Technical Reports Server (NTRS)

    Dunagan, Stephen E.

    1989-01-01

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

  15. Solar Doppler shifts - Sources of continuous spectra

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Harvey, J. W.

    1986-01-01

    Oscillation observations can be used to study nonoscillatory solar phenomena that exhibit Doppler shifts. The paper discusses several effects of these phenomena and their associated temporal and spatial power spectra: (1) they limit the signal-to-noise ratio and sometimes detectability of oscillation modes; (2) there is the potential for better understanding and/or detection of solar phenomena; (3) large-scale convection may spatially modulate oscillation modes, leading to a continuous background spectrum; and (4) in regions of the spectrum where the resolution to separate modes is lacking one can determine upper limits for the integrated effects of modes.

  16. Adaptive responses of cardiac function to fetal postural change as gestational age increases

    PubMed Central

    Kim, Woo Jin; Choi, Hye Jin; Yang, Sun Young; Koo, Boo Hae; Ahn, Ki Hoon; Hong, Soon Cheol; Oh, Min-Jeong; Kim, Hai-Joong

    2016-01-01

    Objective The cardiovascular system maintains homeostasis through a series of adaptive responses to physiological requirements. However, little is known about the adaptation of fetal cardiac function to gravity, according to gestational age. In the present study, we aimed to evaluate the adaptive responses of cardiac function to postural changes, using Tei index measurements. Methods Fetal echocardiography and Doppler examination were performed on 114 women with vertex singleton pregnancies at 19 to 40 weeks' gestation. Participants were placed in an upright seated position, and the Tei index for fetal left ventricular cardiac function was measured. The women were then moved into a supine position and the Tei index was re-measured. Results The mean Tei index when measured in an upright seated position was significantly lower than that measured in a supine positioning for all fetuses (0.528±0.103 vs. 0.555±0.106, P=0.014, respectively). This difference was also noted in fetuses with a gestational age of 28–40 weeks (0.539±0.107 vs. 0.574±0.102, P=0.011, respectively). However, there was no difference in the Tei index between an upright seated and a supine position among fetuses with a gestational age of <28 weeks (0.505±0.091 vs. 0.516±0.103, P=0.571, respectively). Conclusion Postural changes from an upright seated to a supine position result in an increased Tei index after a gestational age of 28 weeks. This appears to reflect maturation in the adaptive responses of the fetal cardiovascular system to postural changes. PMID:27896244

  17. Value of doppler ultrasonography in the study of hemodialysis peripheral vascular access dysfunction.

    PubMed

    Moreno Sánchez, T; Martín Hervás, C; Sola Martínez, E; Moreno Rodríguez, F

    2014-01-01

    The main objectives of this study were to evaluate the sensitivity and specificity of duplex Doppler ultrasonography in the study of hemodialysis peripheral vascular access dysfunction and to analyze the resistance index and flow in the afferent artery. We prospectively studied 178 patients with 178 peripheral vascular accesses that were dysfunctional in at least three consecutive hemodialysis sessions. Patients underwent duplex Doppler ultrasonography and clinical and laboratory follow-up for three months (provided angiography findings were negative). We calculated the sensitivity, specificity, predictive values, and coefficients of probability. We studied the morphology of the afferent artery, the arteriovenous anastomosis, and the efferent vein, and we measured the resistance index and the flow of the afferent artery, the diameter of the anastomosis, and the flow and peak systolic velocity in the efferent vein. The final sample consisted of 159 patients. The sensitivity, specificity, positive and negative predictive values, and positive and negative coefficients of probability were 0,98 (95% CI: 0,88-1.00), 0,74 (95% CI: 0,66-0,81), 0,96, 0,82, 3.7, and 0,03, respectively. The resistance index was less than 0,5 in 78.5% of the peripheral vascular accesses with normal function and greater than 0,5 in 86.1% of the dysfunctional peripheral vascular accesses. We found aneurysms in 19 of the native peripheral vascular accesses and pseudoaneurysms in 7 of the prosthetic grafts. Inverted flow was seen in 57 peripheral vascular accesses. Duplex Doppler ultrasonography is an efficacious method for detecting and characterizing stenosis and thrombosis in peripheral vascular accesses, and it provides information about the morphology and hemodynamics. Copyright © 2012 SERAM. Published by Elsevier Espana. All rights reserved.

  18. The effect of nifedipine tocolysis on Doppler indices of the uterine and umbilical arteries.

    PubMed

    Ulubaşoğlu, Hasan; Özmen Bayar, Ülkü; Kaya, Cihan; Ungan, Burcu

    2015-06-01

    The aim of this study was to evaluate the effect of oral nifedipine on Doppler indices of the uterine artery (UtA) and umbilical artery (UA) before and 24 hours, 48 hours, and 1 week after tocolytic treatment. This was a prospective, self-controlled, cohort study of 65 pregnant women undergoing nifedipine tocolysis. Doppler assessment of the UtA and UA was performed before treatment and 24 hours, 48 hours, and 1 week after the initial 4 doses of 10 mg of oral nifedipine, administered at 20-minute intervals. The maintenance dosage was 20 mg of oral nifedipine administered every 6 hours for 48 hours, for a total dose of 80 mg/day. There was a decrease in the 24-hour values of the UA pulsatility index, resistance index (RI), systolic-diastolic (S:D) ratio, right UtA pulsatility index, RI, S:D ratio, and left UtA RI and S:D ratio with nifedipine therapy in comparison with the values recorded prior to nifedipine therapy. However, these differences were not statistically significant. There were no statistically significant differences between the data recorded prior to nifedipine administration and those obtained at 48 hours and 1 week after treatment. Oral nifedipine is a safe tocolytic agent with no long-term effect on fetomaternal circulation in pregnant women at risk of preterm delivery. © 2014 Wiley Periodicals, Inc.

  19. Uterine blood flow during various stages of pregnancy in dairy buffaloes using transrectal Doppler ultrasonography.

    PubMed

    Varughese, E E; Brar, P S; Dhindsa, S S

    2013-07-01

    Reference data to assess function and perfusion of uteroplacental tissues by assessment of uterine blood flow parameters is not available in buffaloes. The objective of the present study was to assess and quantify blood flow parameters at various stages of gestation. A total of 54 Murrah buffaloes, six animals at every month of gestation, from two months to ten months, were subjected to transrectal Doppler ultrasonography to assess uterine blood flow in both the middle uterine arteries. Resistance and pulsatility indices, velocity and volume of blood flow, diameter of the artery and notch signal were measured for different waveforms. The resistance index value was positively correlated with pulsatility index (r=0.94, P<0.05) but negatively correlated with all other parameters for both arteries, ipsilateral and contralateral to the fetus. With a significant advancement of pregnancy, there was reduction in resistance index with a significant increase in velocity, volume of blood flow and diameter in both arteries. There was a significant increase in the volume and velocity of blood flow (P<0.05) during the last trimester with increased growth demands of the fetus. The notch signal disappeared by 20-24 weeks. Thus, transrectal Doppler ultrasongraphy proved to be a useful non-invasive method to assess the uterine blood flow during pregnancy in buffaloes. This could be a valuable tool to ascertain hemodynamic changes in complicated pregnancy (e.g. abnormalities in uterine blood flow/placenta/fetus) and its extent of deviation from normal.

  20. Doppler ultrasound in kidney diseases: a key parameter in clinical long-term follow-up.

    PubMed

    Spatola, Leonardo; Andrulli, Simeone

    2016-12-01

    Doppler ultrasound has been extensively used in detecting reno-vascular diseases, showing to be a non-invasive, safe, low cost and repeatable tool. The Renal Resistive Index (RRI) [(peak systolic velocity - end diastolic velocity)/peak systolic velocity] is a semi-quantitative index derived by Doppler evaluation of renal vascular bed. Normally RRI is in the range of 0.47-0.70, it increases with aging and, usually, it shows a difference between the two kidneys less than 5-8 %. RRI is an important prognostic marker in chronic kidney diseases (CKD), both in diabetic and non-diabetic kidney diseases, because, in longitudinal prospective studies, it significantly correlated with hemodynamic (ABPM, SBP, DBP, pulse pressure) and histopathological parameters (glomerular sclerosis, arteriolosclerosis, interstitial fibrosis/tubular atrophy, interstitial infiltration). In acute kidney injury (AKI) RI is a valid tool in differentiating between pre-renal and renal failure and in predicting renal response to vaso-active agents. In addition a RRI >0.74 can predict the onset of AKI in septic patients. Renal Resistive Index is a useful marker in allograft diseases because it has been widely showed a correlation with histological lesions during worsening of renal function, both in acute rejection and in chronic allograft nephropathy. Recent studies suggest its role in the risk of new onset diabetes after transplantation and it could be one of the parameters to evaluate to shift or withdrawal immunological and/or hypertensive therapy.

  1. WANTED: Fully Automated Indexing.

    ERIC Educational Resources Information Center

    Purcell, Royal

    1991-01-01

    Discussion of indexing focuses on the possibilities of fully automated indexing. Topics discussed include controlled indexing languages such as subject heading lists and thesauri, free indexing languages, natural indexing languages, computer-aided indexing, expert systems, and the need for greater creativity to further advance automated indexing.…

  2. Is Doppler ultrasound useful for evaluating gestational trophoblastic disease?

    PubMed

    Lin, Lawrence H; Bernardes, Lisandra S; Hase, Eliane A; Fushida, Koji; Francisco, Rossana P V

    2015-12-01

    Doppler ultrasound is a non-invasive method for evaluating vascularization and is widely used in clinical practice. Gestational trophoblastic neoplasia includes a group of highly vascularized malignancies derived from placental cells. This review summarizes data found in the literature regarding the applications of Doppler ultrasound in managing patients with gestational trophoblastic neoplasia. The PubMed/Medline, Web of Science, Cochrane and LILACS databases were searched for articles published in English until 2014 using the following keywords: "Gestational trophoblastic disease AND Ultrasonography, Doppler." Twenty-eight articles met the inclusion criteria and were separated into the 4 following groups according to the aim of the study. (1) Doppler ultrasound does not seem to be capable of differentiating partial from complete moles, but it might be useful when evaluating pregnancies in which a complete mole coexists with a normal fetus. (2) There is controversy in the role of uterine artery Doppler velocimetry in the prediction of development of gestational trophoblastic neoplasia. (3) Doppler ultrasound is a useful tool in the diagnosis of gestational trophoblastic neoplasia because abnormal myometrial vascularization and lower uterine artery Doppler indices seem to be correlated with invasive disease. (4) Lower uterine artery Doppler indices in the diagnosis of gestational trophoblastic neoplasia are associated with methotrexate resistance and might play a role in prognosis. Several studies support the importance of Doppler ultrasound in the management of patients with gestational trophoblastic neoplasia, particularly the role of Doppler velocimetry in the prediction of trophoblastic neoplasia and the chemoresistance of trophoblastic tumors. Doppler findings should be used as ancillary tools, along with human chorionic gonadotropin assessment, in the diagnosis of gestational trophoblastic neoplasia.

  3. Is Doppler ultrasound useful for evaluating gestational trophoblastic disease?

    PubMed Central

    Lin, Lawrence H; Bernardes, Lisandra S; Hase, Eliane A; Fushida, Koji; Francisco, Rossana P V

    2015-01-01

    Doppler ultrasound is a non-invasive method for evaluating vascularization and is widely used in clinical practice. Gestational trophoblastic neoplasia includes a group of highly vascularized malignancies derived from placental cells. This review summarizes data found in the literature regarding the applications of Doppler ultrasound in managing patients with gestational trophoblastic neoplasia. The PubMed/Medline, Web of Science, Cochrane and LILACS databases were searched for articles published in English until 2014 using the following keywords: “Gestational trophoblastic disease AND Ultrasonography, Doppler.” Twenty-eight articles met the inclusion criteria and were separated into the 4 following groups according to the aim of the study. 1 Doppler ultrasound does not seem to be capable of differentiating partial from complete moles, but it might be useful when evaluating pregnancies in which a complete mole coexists with a normal fetus. 2 There is controversy in the role of uterine artery Doppler velocimetry in the prediction of development of gestational trophoblastic neoplasia. 3 Doppler ultrasound is a useful tool in the diagnosis of gestational trophoblastic neoplasia because abnormal myometrial vascularization and lower uterine artery Doppler indices seem to be correlated with invasive disease. 4 Lower uterine artery Doppler indices in the diagnosis of gestational trophoblastic neoplasia are associated with methotrexate resistance and might play a role in prognosis. CONCLUSION: Several studies support the importance of Doppler ultrasound in the management of patients with gestational trophoblastic neoplasia, particularly the role of Doppler velocimetry in the prediction of trophoblastic neoplasia and the chemoresistance of trophoblastic tumors. Doppler findings should be used as ancillary tools, along with human chorionic gonadotropin assessment, in the diagnosis of gestational trophoblastic neoplasia. PMID:26735221

  4. Acute Haemodialysis-induced Changes in Tissue Doppler Echocardiography Parameters.

    PubMed

    Sağ, Saim; Yeşilbursa, Dilek; Yıldız, Abdulmecit; Dilek, Kamil; Sentürk, Tunay; Serdar, Osman Akın; Aydınlar, Ali

    2014-09-01

    Tissue Doppler imaging (TDI) is a method that determines the tissue motion and velocity within the myocardium. To characterize acute haemodialysis (HD)-induced changes in TDI-derived indices for patients that have end-stage renal disease (ESRD). Cross sectional study. Conventional echocardiography and TDI methods were applied to study ESRD patients (n=58) before and after HD. Pulmonary venous flow, mitral inflow, and TDI signals of the lateral and septal mitral annulus were examined for the determination of altered left-ventricular diastolic filling parameters. Flow velocities from early- (E) and late-atrial (A) peak transmitral; peak pulmonary vein systolic (S) and diastolic (D); and myocardial peak systolic (Sm) and peak early (Em) and late (Am) diastolic mitral annular velocities were also assessed for changes. Transmitral E and A velocities and the E/A ratio decreased significantly after HD (p<0.001). Pulmonary vein S (p<0.001) and D (p<0.001) velocities decreased, and S/D ratios increased significantly (p=0.027). HD led to a reduction in septal Em (p<0.001), lateral Em (p=0.006), and Am (p<0.001) velocities. Contrary to the decreases in Em and Am, the Em/Am ratio remained unchanged. A single HD session was associated with an acute deterioration in the diastolic parameters. Since the Em/Am ratio remained unchanged, we conclude that this index is a relatively load-independent measure of diastolic function in HD patients.

  5. Transcranial doppler and near infrared spectroscopy in the perioperative period.

    PubMed

    Kampf, Stephanie; Schramm, Patrick; Klein, Klaus Ulrich

    2013-10-01

    Maintenance of adequate blood flow and oxygen to the brain is one of the principal endpoints of all surgery and anesthesia. During operations in general anesthesia, however, the brain is at particular risk for silent ischemia. Despite this risk, the brain still remains one of the last monitored organs in clincial anesthesiology. Transcranial Doppler (TCD) sonography and near-infrared spectroscopy (NIRS) experience a revival as these noninvasive technologies help to detect silent cerebral ischemia. TCD allows for quantification of blood flow velocities in basal intracranial arteries. TCD-derived variables such as the pulsatility index might hint toward diminished cognitive reserve or raised intracranial pressure. NIRS allows for assessment of regional cerebral oxygenation. Monitoring should be performed during high-risk surgery for silent cerebral ischemia and special circumstances during critical care medicine. Both techniques allow for the assessment of cerebrovascular autoregulation and individualized management of cerebral hemodynamics. TCD and NIRS are noninvasive monitors that anesthesiologists apply to tailor cerebral oxygen delivery, aiming to safeguard brain function in the perioperative period.

  6. Assessment of diastolic function by tissue Doppler echocardiography: comparison with standard transmitral and pulmonary venous flow

    NASA Technical Reports Server (NTRS)

    Farias, C. A.; Rodriguez, L.; Garcia, M. J.; Sun, J. P.; Klein, A. L.; Thomas, J. D.

    1999-01-01

    The objective of this study was to determine the utility of Doppler tissue echocardiography in the evaluation of diastolic filling and in discriminating between normal subjects and those with various stages of diastolic dysfunction. We measured myocardial velocities in 51 patients with various stages of diastolic dysfunction and in 27 normal volunteers. The discriminating power of each of the standard Doppler indexes of left ventricular filling, pulmonary venous flow, and myocardial velocities was determined with the use of Spearman rank correlation and analysis of variance F statistics. Early diastolic myocardial velocity (E(m)) was higher in normal subjects (16.0 +/- 3.8 cm/s) than in patients with either delayed relaxation (n = 15, 7.5 +/- 2.2 cm/s), pseudonormal filling (n = 26, 7.6 +/- 2.3 cm/s), or restrictive filling (n = 10, 7.4 +/- 2.4 cm/s, P <.0001). E(m ) was the best single discriminator between control subjects and patients with diastolic dysfunction (P =.7, F = 64.5). Myocardial velocities assessed by Doppler tissue echocardiography are useful in differentiating patients with normal from those with abnormal diastolic function. Myocardial velocity remains reduced even in those stages of diastolic dysfunction characterized by increased preload compensation.

  7. Role of Doppler Sonography in Early Detection of Splenic Steal Syndrome.

    PubMed

    Li, Chaolun; Quintini, Cristiano; Hashimoto, Koji; Fung, John; Obuchowski, Nancy A; Sands, Mark J; Wang, Weiping

    2016-07-01

    To retrospectively investigate the role of Doppler sonography in the early detection of splenic steal syndrome. Fifty cases of splenic steal syndrome after orthotopic liver transplantation were identified. A control group was matched to the splenic steal syndrome group. Information was collected about the clinical presentation, liver enzyme levels, Doppler sonographic results, and follow-up after patients underwent splenic artery embolization. A persistent hepatic arterial diastolic reversal waveform was observed in 25 patients with splenic steal syndrome versus 0 control patients. The mean hepatic arterial resistive index (RI) values ± SD were 0.95 ± 0.09 in patients with splenic steal syndrome and 0.80 ± 0.10 in control patients (P < .0001). One week after orthotopic liver transplantation, the area under the receiver operating characteristic curve for the RI was 0.884 (95% confidence interval, 0.793-0.975; P = .001) for splenic steal syndrome diagnosis. After splenic artery embolization, there was normalization of the reversal waveform, with an average RI of 0.77 ± 0.11 (P < .0001). Dynamic changes in the hepatic arterial waveform and RI are keys to detecting splenic steal syndrome with Doppler sonography.

  8. Design of a near-IR Doppler instrument for planet searches

    NASA Astrophysics Data System (ADS)

    Zhao, Bo; Ge, Jian; Nguyen, Duy Cuong; Wang, Ji; Groot, John

    2010-07-01

    Doppler searches are extending to the near infrared to detect and characterize habitable planets around low mass stars. We present an optical design and performance of a near-IR Doppler instrument. This instrument has two operating modes covering 0.8-1.8 microns. One mode is called IRET, which consists of a fix-delay interferometer and a crossdispersed echelle spectrograph to simultaneously cover 0.8-1.35 microns with a spectral resolution of R=22000 on a 2k x 2k H2RG IR array. The other mode is called FIRST, which uses a silicon immersion grating as the main disperser to simultaneously cover 1.4-1.8 microns with a spectral resolution of R=55000 on the same detector as IRET. The triplepass parabola white pupil design is used to restrain background scatter radiation with stable configuration for precision radial velocity measurements. We used high index standard glasses for camera optics and VPH gratings as crossdispersers in both modes. The FIRST mode can be switched in and out conveniently while the IRET mode is kept without moving parts to increase its stability. This instrument is designed to deliver up to 1 m/s Doppler precision RV measurements of nearby bright M dwarfs at the Apache Point Observatory 3.5 meter telescope. The instrument is expected to be operational in the spring 2011.

  9. Doppler flow evaluation can anticipate abnormal left lung perfusion after transcatheter closure of patent ductus arteriosus.

    PubMed

    Soares, Andressa M; Aiello, Vera D; Andrade, José L; Kajita, Luis J; Soares, José; Morhy, Samira S; Mathias, Wilson; Lopes, Antonio A B; Ramires, José A F

    2004-11-01

    Coil protrusion into the left pulmonary artery (LPA) has been described after transcatheter closure of the patent ductus arteriosus (PDA). The possible impact of such a finding in lung perfusion has not been completely clarified. We evaluated Doppler flow velocities and lung perfusion in patients submitted to that procedure. After transcatheter closure of PDA with coils, 70 patients (mean age 8.6+/-3.4 years) were followed for a period of 3.6+/-0.9 years (range 2.1-5.9) and compared to 22 controls. Peak flow velocities and coil protrusion were assessed by Doppler echocardiography. A Doppler velocity index (DVI) was calculated by the difference between the LPA and right pulmonary artery (RPA) peak flow velocities relative to the pulmonary trunk (PT) expressed in percentage, as follows: DVI=(LPA velocity - RPA velocity)/PT velocity x 100. Lung scintigraphy was performed using (99m)Tc-labelled macro-aggregated albumin. Device protrusion was observed in 94% of the patients, 10% of whom presented abnormal left lung perfusion. Peak LPA velocity and DVI were significantly greater in patients (p=0.001) and correlated negatively with left lung perfusion values (R(2)=0.21 and R(2)=0.65, respectively). A cut-off value of 50% for the DVI showed high sensitivity and specificity for reduced lung perfusion. Impaired left lung perfusion may appear following transcatheter closure of PDA with coils and the determination of DVI may anticipate such alteration.

  10. Changes in uterine artery Doppler flow velocity waveforms during the third stage of labor.

    PubMed

    Maymon, R; Herman, A; Halperin, R; Bukovsky, I; Weinraub, Z; Ariely, S

    1995-01-01

    Transabdominal Doppler velocity waveform measurements of the uterine arteries during the third stage of labor were performed upon 25 patients with uncomplicated vaginal deliveries and 5 with prolonged third stage in order to further assess third-stage mechanisms. Based on Doppler flow measurements, three phases of the third stage of labor were observed: (1) a latent phase with a systolic/diastolic ratio (S/D) and a pulsatility index (PI) of 2.14 +/- 0.49 and 0.89 +/- 0.17, respectively; (2) a contraction and detachment phase with an S/D and PI of 2.53 +/- 0.53 and 1.28 +/- 0.37, respectively, and (3) an expulsion phase with an S/D and PI of 2.20 +/- 0.34 and 0.91 +/- 0.20, respectively (p < 0.05). During the third stage of labor, it was shown that uterine contractions squeezed the uterine vessels as they traversed the myometrium, leading to an increase in the extrinsic resistance, which was reflected by high resistance flow. Following placental separation and changes in the placental-site wall, there was slight uterine relaxation resulting in decreased uterine vessel resistance. This observation encourages the authors to continue investigating the contribution of ultrasound and Doppler flow for studies of the postpartum period.

  11. ALADIN doppler wind lidar: recent advances

    NASA Astrophysics Data System (ADS)

    Morancais, Didier; Fabre, Frédéric; Endemann, Martin; Culoma, Alain

    2007-10-01

    The Atmospheric Laser Doppler Instrument (ALADIN) is the payload of the ADM-Aeolus mission, which will provide direct measurements of global wind fields. It will determine the wind velocity component normal to the satellite velocity vector. The instrument is a direct detection Doppler Lidar operating in the UV, which will be the first of its kind in space. ALADIN comprises a high energy laser and a direct detection receiver operating on aerosol and molecular backscatter signals in parallel. The laser is all solid-state, based on Nd-YAG technology and high power laser diodes. The detector is a silicon CCD whose architecture allows on-chip accumulation of the returns, providing photon counting performance. The 1.5 m diameter telescope is lightweight, all made of silicon carbide. ALADIN is now in its final construction stage: the integration of the Flight Model is on-going. Most of the subsystems have been integrated; the payload performance and qualification test campaign will commence. This paper briefly describes the instrument design and provides insights on the development status and the results obtained so far. This regards in particular the receiver performance, the telescope development and the challenges of the laser. The Aeolus satellite is developed for the European Space Agency by EADS Astrium Satellites as prime contractor for the satellite and the instrument.

  12. Fiber Scrambling for Extreme Doppler Precision

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  13. Ambiguity resolution for satellite Doppler positioning systems

    NASA Technical Reports Server (NTRS)

    Argentiero, P.; Marini, J.

    1979-01-01

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

  14. [Intracranial blood flow velocities evaluated by color Doppler (duplex) in preterm infants].

    PubMed

    de Assis, Marcelo Cardoso; Machado, Helio Rubens

    2004-03-01

    In order to ascertain the blood flow velocities in the intracranial arteries we evaluated 73 preterm neonates during a period ranging from June 1994 to March 1999. These preterm infants were divided in two separate groups, 18 healthy and 55 with intracranial hemorrhage. They were subjected to sequential measurements of blood flow velocities in the intracranial arteries. The gestational age of the whole group varied from 28 to 36 weeks and birth weights between 720 and 2530 g. The diagnosis of the intracerebral hemorrhages in these preterm neonates were done using high resolution gray and color scale transfontanellar ultrasonography brain scans. The ultrasound evaluations were performed in the initial 3rd, 7th and 14th day of life. The 73 preterm infants were evaluated with sequential measurements of blood flow velocity in the intracranial arteries using the Doppler technique through the anterior fontanelle. Doppler evaluation of the cerebral vessels were performed on days 3, 7, 30 and 90 of life. These evaluations were performed in the six intracranial arteries, meaning: right and left anterior and middle cerebral arteries and right and left internal carotid arteries. Doppler recordings were made using Duplex Color-Doppler system, pulse echo probe of 3,5; 5,0 and 7,5 MHz. Measuring the blood flow velocity in the cerebral arteries we obtained a maximum systolic velocity and end diastolic velocity with a rate in meters per second (m/s) for each cardiac cycle. After obtaining these numerical values for these velocities we obtained the resistance index (RI) or Pourcelot index. In a progressive way as the resistance index (RI) values were being obtained in each stage of this study they were also being checked in the cerebral arteries of healthy preterm infants and infants with intracranial hemorrhages. We also analyzed in a comparative method the values of the resistive index between the two groups of preterm infants observing their behaviour. The results obtained when

  15. Assessment of the Effects of Low-Level Laser Therapy on the Thyroid Vascularization of Patients with Autoimmune Hypothyroidism by Color Doppler Ultrasound

    PubMed Central

    Höfling, Danilo Bianchini; Chavantes, Maria Cristina; Juliano, Adriana G.; Cerri, Giovanni G.; Knobel, Meyer; Yoshimura, Elisabeth M.; Chammas, Maria Cristina

    2012-01-01

    Background. Chronic autoimmune thyroiditis (CAT) frequently alters thyroid vascularization, likely as a result of the autoimmune process. Objective. To evaluate the effects of low-level laser therapy (LLLT) on the thyroid vascularization of patients with hypothyroidism induced by CAT using color Doppler ultrasound parameters. Methods. In this randomized clinical trial, 43 patients who underwent levothyroxine replacement for CAT-induced hypothyroidism were randomly assigned to receive either 10 sessions of LLLT (L group, n = 23) or 10 sessions of a placebo treatment (P group, n = 20). Color Doppler ultrasounds were performed before and 30 days after interventions. To verify the vascularity of the thyroid parenchyma, power Doppler was performed. The systolic peak velocity (SPV) and resistance index (RI) in the superior (STA) and inferior thyroid arteries (ITAs) were measured by pulsed Doppler. Results. The frequency of normal vascularization of the thyroid lobes observed in the postintervention power Doppler examination was significantly higher in the L than in the P group (P = 0.023). The pulsed Doppler examination revealed an increase in the SPV of the ITA in the L group compared with the P group (P = 0.016). No significant differences in the SPV of the STA and in the RI were found between the groups. Conclusion. These results suggest that LLLT can ameliorate thyroid parenchyma vascularization and increase the SPV of the ITA of patients with hypothyroidism caused by CAT. PMID:23316383

  16. Plasma aldosterone and left ventricular diastolic function in treatment-naïve patients with hypertension: tissue-Doppler imaging study.

    PubMed

    Catena, Cristiana; Verheyen, Nicolas; Pilz, Stefan; Kraigher-Krainer, Elisabeth; Tomaschitz, Andreas; Sechi, Leonardo A; Pieske, Burkert

    2015-06-01

    Aldosterone has hypertrophic and profibrotic effects on the heart. The relationship between plasma aldosterone levels and left ventricular diastolic function in hypertension, however, is unclear. The aim of this study was to examine this relationship in treatment-naïve hypertensive patients free of comorbidities that could affect left ventricular diastolic filling properties. In 115 patients with primary hypertension who were eating a standard diet and 100 matched normotensive controls, we measured plasma aldosterone and active renin levels and performed both conventional echocardiography and tissue-Doppler imaging for assessment of left ventricular diastolic function. Left ventricular hypertrophy was found in 21% of hypertensive patients, and diastolic dysfunction was detected in 20% by conventional echocardiography and in 58% by tissue-Doppler imaging. Patients with left ventricular diastolic dysfunction at tissue-Doppler imaging were older and more frequently men, had greater body mass index, blood pressure, alcohol intake, left ventricular mass index, relative wall thickness, and lower plasma aldosterone levels than patients with preserved diastolic function. Plasma aldosterone correlated directly with left ventricular mass index in addition to age, body mass index, and systolic blood pressure. Plasma aldosterone was also directly related to e' velocity at tissue-Doppler imaging, but this relationship was lost after multivariate adjustment. In conclusion, plasma aldosterone levels are associated with left ventricular hypertrophy but have no independent relationship with left ventricular diastolic properties in hypertensive patients.

  17. [Assessment of the microcirculation system by laser Doppler flowmetry].

    PubMed

    Barkhatov, I V

    2013-01-01

    Laser Doppler flowmetry (LDF) is extensively used to study microcirculatory disorders, a main problem facing modern medicine. A wealth of data have been obtained on microcirculation in diabetes mellitus, HD, venous insufficiency and other diseases. This review focuses on basic principles of the method for the assessment of microcirculatory disorders by LDF using the domestically produced equipment. The main elements of the microcirculation system, capillary hemodynamics, and mechanisms of its regulation are described. The main elements and terms of LDF are considered, such as microcirculation index, flux, and variation coefficient along with elements of analysis of the amplitude-frequency fluctuation spectrum and different types of tissue blood flow. Active factors of microcirculation control modulate the blood flow from the vascular wall; their action is mediated through its muscular component. Passive factors cause variations of blood flow outside the microcirculation system; they are the pulsed wave originating from arteries and the sucking action of the venous respiratory pump. Under normal conditions, the vasomotor rhythm driven by the pacemaker in the precapillary segment of the microcirculation bed predominates. The compensatory role of other regulatory mechanisms increases with decreasing contribution of vasomotion to the active modulation of microcirculation hemodynamics. A change in the low to high frequency rhythm ratio reflects the microcirculation index (MI). In case of well-balanced active vasomotor and passive compensatory modulations of tissue blood flow observed in normoemic type of microcirculation, MI amounts to 2.2 ± 0.05. Enhancement of high-frequency and pulsed fluctuation spectra results in a decrease of MI to 1.73 ± 0.04 (hyperemic type) and 1.86 ± 0.053 (hypoemic type).

  18. Intraoperative Micro-Doppler in Cerebral Arteriovenous Malformations.

    PubMed

    Burkhardt, Till; Siasios, Giannis; Schmidt, Nils Ole; Reitz, Mathias; Regelsberger, Jan; Westphal, Manfred

    2015-11-01

    Intraoperative micro-Doppler (IOMD), intraoperative digital substraction angiography (DSA), and microscope-integrated indocyanine green angiography are methods that guide neurosurgical resection of arteriovenous malformations (AVMs) in the brain and minimize the trauma of healthy tissue. In this study we emphasize the use of IOMD in AVM surgery, analyzing the advantages and the limitations of this method. Patients and A total of 32 patients were diagnosed with an AVM. Supplying arteries and draining veins were analyzed regarding hemodynamic profiles, flow velocities, pulsatility index (PI), and resistance index (RI). Venous drainages were accompanied by arterial blood flow disturbances that showed typical characteristics in all cases. We set an angle of 60 degrees between the examined vessel and the probe to achieve a more reliable and comparable measurement. Postoperative DSA was performed in all patients. Supplying arterial blood vessels of AVMs could be identified by their characteristic blood flow profiles with PI < 0.7 and RI < 0.55. Drainage veins in all 32 cases showed normalized venous flow patterns without arterial flow turbulences at the end of the surgical procedure. Postoperative DSA revealed a residual AVM in one patient. IOMD constitutes a safe, accurate, and low-cost imaging modality for evaluating blood flow velocities and for optimal stepwise AVM elimination without unnecessary sacrifice of veins. PI and RI are reliable parameters in diagnosing cerebrovascular malformations, but systolic and diastolic flow velocities may vary to a greater extent. This phenomenon has never been elucidated previously and therefore needs to be emphasized when using this technique intraoperatively. Georg Thieme Verlag KG Stuttgart · New York.

  19. Micro-Doppler classification of riders and riderless horses

    NASA Astrophysics Data System (ADS)

    Tahmoush, David

    2014-05-01

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

  20. New Doppler echocardiographic applications for the study of diastolic function

    NASA Technical Reports Server (NTRS)

    Garcia, M. J.; Thomas, J. D.; Klein, A. L.

    1998-01-01

    Doppler echocardiography is one of the most useful clinical tools for the assessment of left ventricular (LV) diastolic function. Doppler indices of LV filling and pulmonary venous (PV) flow are used not only for diagnostic purposes but also for establishing prognosis and evaluating the effect of therapeutic interventions. The utility of these indices is limited, however, by the confounding effects of different physiologic variables such as LV relaxation, compliance and filling pressure. Since alterations in these variables result in changes in Doppler indices of opposite direction, it is often difficult to determine the status of a given variable when a specific Doppler filling pattern is observed. Recently, color M-mode and tissue Doppler have provided useful insights in the study of diastolic function. These new Doppler applications have been shown to provide an accurate estimate of LV relaxation and appear to be relatively insensitive to the effects of preload compensation. This review will focus on the complementary role of color M-mode and tissue Doppler echocardiography and traditional Doppler indices of LV filling and PV flow in the assessment of diastolic function.

  1. 21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section 892.1550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler...

  2. Doppler weather radar with predictive wind shear detection capabilities

    NASA Technical Reports Server (NTRS)

    Kuntman, Daryal

    1991-01-01

    The status of Bendix research on Doppler weather radar with predictive wind shear detection capability is given in viewgraph form. Information is given on the RDR-4A, a fully coherent, solid state transmitter having Doppler turbulence capability. Frequency generation data, plans, modifications, system characteristics and certification requirements are covered.

  3. 21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section 892.1550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging...

  4. 21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section 892.1550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1550 Ultrasonic pulsed doppler imaging...

  5. Tissue Doppler characterization of cardiac phenotype in mouse.

    PubMed

    Fayssoil, Abdallah

    2009-10-01

    Mice allow biologists to study various genes playing a role in cardiac function and pathophysiological situations. Echocardiography is a non-invasive tool for assessing cardiac phenotype. Because of load dependence of conventional parameters (left ventricular shortening fraction, left ventricular ejection fraction and mitral pulsed Doppler), we have to perform Doppler tissular velocity imaging and strain imaging for the characterization of cardiomyopathies mice models.

  6. Ionospheric observations made by a time-interleaved Doppler ionosonde

    NASA Astrophysics Data System (ADS)

    Lynn, Kenneth J. W.

    2008-10-01

    Mid-latitude HF observations of ionospheric Doppler velocity as a function of frequency are reported here as observed over a quiet 24-h period by a KEL IPS71 ionosonde operating at a 5-min sampling rate. The unique time-interleaving technique used in this ionosonde provided a Doppler resolution of 0.04 Hz over a Doppler range of ±2.5 Hz at each sounding frequency via FFT processing and is described here for the first time. The time-interleaving technique can be applied to other types of ionosonde as well as to other applications. The measurements described were made at a middle latitude site (Salisbury, South Australia). Doppler variations (<30 min) were ever present throughout the day and showed short-period TID characteristics. The day-time Doppler shift was found to closely follow the rate-of-change of foF2 as predicted by a simple parabolic layer model. The descending cusp in short-period TIDs is shown to mark an abrupt change with increasing frequency from negative towards positive Doppler shift with the greatest change in Doppler shift being observed below the cusp. The “smilergram” is introduced as observed in both F2 and Sporadic E. The characteristic curve in Doppler versus group height at a single frequency is described and related to changes in reflection symmetry, velocity and depth of moving ionospheric inhomogeneities.

  7. Imaging doppler velocimeter with downward heterodyning in the optical domain

    DOEpatents

    Reu, Phillip L; Hansche, Bruce D

    2013-05-21

    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.

  8. Investigations of atmospheric dynamics using a CW Doppler sounder array

    NASA Technical Reports Server (NTRS)

    Rao, G. L.

    1974-01-01

    A three-dimensional CW Doppler sounding system currently under operation at the NASA-Marshall Space Flight Center, Alabama is described. The properties of the neutral atmosphere are discussed along with the theory of Doppler sounding technique. Methods of data analyses used to investigate the dynamical phenomena at the ionospheric heights are presented and suggestions for future investigations provided.

  9. An elementary approach to the gravitational Doppler shift

    NASA Astrophysics Data System (ADS)

    Wörner, C. H.; Rojas, Roberto

    2017-01-01

    In college physics courses, treatment of the Doppler effect is usually done far from the first introduction to kinematics. This paper aims to apply a graphical treatment to describe the gravitational redshift, by considering the Doppler effect in two accelerated reference frames and exercising the equivalence principle. This approach seems appropriate to discuss with beginner students and could serve to enrich the didactic processes.

  10. 21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section 892.1550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that combines...

  11. 21 CFR 892.1550 - Ultrasonic pulsed doppler imaging system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ultrasonic pulsed doppler imaging system. 892.1550 Section 892.1550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... system. (a) Identification. An ultrasonic pulsed doppler imaging system is a device that combines...

  12. Fixed region of nondistensibility after coarctation repair: in vitro validation of its influence on Doppler peak velocities.

    PubMed

    Verhaaren, H; De Mey, S; Coomans, I; Segers, P; De Wolf, D; Matthys, D; Verdonck, P

    2001-06-01

    After coarctectomy, local loss of distensibility is noted in addition to mild anatomic narrowing. We hypothesize that the increased Doppler peak velocities measured at the aortic isthmus in these patients partly reflect obstruction secondary to the stiff surgical scar. The hypothesis was studied in a pulsatile hydraulic model. Thirty-one patients (13.0 +/- 4.0 years of age), 10.5 +/- 4.7 years after coarctectomy by end-to-end anastomosis, were studied clinically and echocardiographically. Indexes of distensibility were calculated. The effect of isolated increased stiffness was studied in vitro with a stiff and a compliant 1:1 scale latex model of the aorta mounted in a pulsatile full-scale circulation loop. Local stiffening was obtained by a rigid ring mounted around the aorta, fitted to the dimension of the unloaded aorta. For different pressure and flow regimens, pressures and Doppler velocities were measured across the ring. Mean peak velocities at the surgical scar were 2.2 +/- 0.4 m/s. Mild anatomic stenosis was present. All distensibility indexes indicated locally increased stiffness (P <.001). In the stiff latex model, Doppler peak velocities increased from 1.89 +/- 0.04 m/s to 2.32 +/- 0.06 m/s (P <.03); in the compliant model, from 1.15 +/- 0.03 m/s to 1.79 +/- 0.05 m/s (P <.001). The increase of Doppler peak velocities depends on model compliance only and is independent of flow rate, length of the noncompliant segment, and viscosity of the perfusion fluid. Velocities do not change when semicircular stiffening is applied. We have demonstrated in vitro that isolated local nondistensibility leads to vessel narrowing during vascular distension. The relative contribution of local scar stiffness in the increase of Doppler peak velocities after coarctectomy was hereby assessed.

  13. Transcranial Doppler investigation of hemodynamic alterations associated with blunt cervical vascular injuries in trauma patients.

    PubMed

    Purvis, Dianna L; Crutchfield, Kevin; Trickey, Amber W; Aldaghlas, Tayseer; Rizzo, Anne; Sikdar, Siddhartha

    2013-10-01

    Blunt cervical vascular injuries, often missed with current screening methods, have substantial morbidity and mortality, and there is a need for improved screening. Elucidation of cerebral hemodynamic alterations may facilitate serial bedside monitoring and improved management. Thus, the objective of this study was to define cerebral flow alterations associated with single blunt cervical vascular injuries using transcranial Doppler sonography and subsequent Doppler waveform analyses in a trauma population. In this prospective pilot study, patients with suspected blunt cervical vascular injuries had diagnoses by computed tomographic angiography and were examined using transcranial Doppler sonography to define cerebral hemodynamics. Multiple vessel injuries were excluded for this analysis, as the focus was to identify hemodynamic alterations from isolated injuries. The inverse damping factor characterized altered extracranial flow patterns; middle cerebral artery flow velocities, the pulsatility index, and their asymmetries characterized altered intracranial flow patterns. Twenty-three trauma patients were evaluated: 4 with single internal carotid artery injuries, 5 with single vertebral artery injuries, and 14 without blunt cervical vascular injuries. All internal carotid artery injuries showed a reduced inverse damping factor in the internal carotid artery and dampened ipsilateral mean flow and peak systolic velocities in the middle cerebral artery. Vertebral artery injuries produced asymmetry of a similar magnitude in the middle cerebral artery mean flow velocity with end-diastolic velocity alterations. These data indicate that extracranial and intracranial hemodynamic alterations occur with internal carotid artery and vertebral artery blunt cervical vascular injuries and can be quantified in the acute injury phase by transcranial Doppler indices. Further study is required to elucidate cerebral flow changes resulting from a single blunt cervical vascular injury

  14. Right Ventricular Doppler Echocardiographic Study of Indeterminate Form of Chagas Disease

    PubMed Central

    Furtado, Rogério Gomes; Frota, Daniela do Carmo Rassi; Silva, João Batista Masson; Romano, Minna Moreira Dias; de Almeida, Oswaldo César; Schmidt, André; Rassi, Salvador

    2015-01-01

    Background Patients with indeterminate form of Chagas disease/cardiac normality (ICD/CN) exhibited normal electrocardiograms and chest X-rays; however, more sophisticated tests detected some degree of morphological and functional changes in the heart. Objective To assess the prevalence of systolic and diastolic dysfunction of the right ventricle (RV) in patients with ICD/CN. Methods This was a case–control and prevalence study. Using Doppler two-dimensional echocardiography (2D), 92 patients were assessed and divided into two groups: group I (normal, n = 31) and group II (ICD/CN, n = 61). Results The prevalence of RV systolic dysfunction in patients in groups I and II was as follows: fractional area change (0.0% versus 0.6%), mobility of the tricuspid annulus (0.0% versus 0.0%), and S-wave tissue Doppler (6.4% versus 26.0%, p = 0.016). The prevalence of global disorders such as the right myocardial performance index using tissue Doppler (16.1% versus 27.8%, p = 0.099) and pulsed Doppler (61.3% versus 68%, p = 0.141) and diastolic disorders such as abnormal relaxation (0.0% versus 6.0%), pseudonormal pattern (0.0% versus 0.0%), and restrictive pattern (0.0% versus 0.0%) was not statistically different between groups. Conclusion The prevalence of RV systolic dysfunction was estimated to be 26% (S wave velocity compared with other variables), suggesting incipient changes in RV systolic function in the ICD/CN group. PMID:25517391

  15. Radiologic importance of a high-resistive vertebral artery Doppler waveform on carotid duplex ultrasonography.

    PubMed

    Kim, Esther S H; Thompson, Megan; Nacion, Kristine M; Celestin, Carmel; Perez, Alejandro; Gornik, Heather L

    2010-08-01

    The appearance of the vertebral artery (VA) waveform on a pulsed Doppler examination performed during standard carotid duplex ultrasonography (CDU) may suggest vertebrobasilar disease. We sought to determine the radiographic importance of high-resistive (HR) pulsed Doppler VA waveforms seen on CDU. The Noninvasive Vascular Laboratory database was queried for CDU studies noting the HR VA Doppler signal. Studies with unilateral or bilateral HR and antegrade VA waveforms with correlative neuroimaging studies within 60 days were included. Imaging reports were reviewed to determine the following: (1) a normal VA; (2) at least moderate distal VA or basilar artery (BA) stenosis, occlusion, or dissection; (3) a congenitally diminutive VA; or (4) other abnormalities. Of 1338 studies with 1 or more HR VA waveforms, 79 studies met all inclusion criteria (n = 157 arteries) and had adequate correlative neuroimaging. There were 90 HR VAs, and HR waveforms were equally distributed between right and left sides. The mean peak systolic velocity of HR versus low-resistive (LR) VAs was 51.7 versus 63.6 cm/s (P = .04); the mean end-diastolic velocity of HR versus LR VAs was 4.6 versus 17.3 cm/s (P < .001); and the resistive index of HR versus LR VAs was 0.92 versus 0.73 (P < .001). Of all HR VAs, 18.9% were normal; 38.9% had distal vertebrobasilar stenosis or occlusion; 35.6% were congenitally diminutive; and 6.7% had other abnormalities (proximal stenosis, excessive tortuosity, fibromuscular dysplasia, and BA hypoplasia). The finding of an HR spectral Doppler signal in the VA was associated with major vertebrobasilar disease (46% of cases) and should prompt additional neuroimaging in the appropriate clinical situation.

  16. Placental findings in late-onset SGA births without Doppler signs of placental insufficiency.

    PubMed

    Parra-Saavedra, M; Crovetto, F; Triunfo, S; Savchev, S; Peguero, A; Nadal, A; Parra, G; Gratacos, E; Figueras, F

    2013-12-01

    To describe placental pathological findings in late-onset small-for-gestational age (SGA) births for which Doppler signs of placental insufficiency are lacking. A series of placentas were evaluated from singleton pregnancies of SGA births (birth weight below the 10th percentile) delivered after 34 weeks with normal umbilical artery Doppler (pulsatility index below the 95th percentile), that were matched by gestational age with adequate-for-gestational age (AGA) controls. Using a hierarchical and standardized system, placental lesions were classified histologically as consequence of maternal underperfusion, fetal underperfusion or inflammation. A total of 284 placentas were evaluated (142 SGA and 142 AGA). In the SGA group, 54.2% (77/142) of the placentas had weights below the 3rd percentile for GA while it was a 9.9% (14/142) in the AGA group (p < 0.001). Only 21.8% (31/142) of SGA placentas were free of histological abnormalities, while it was 74.6% (106/142) in the AGA group (p < 0.001). In the abnormal SGA placentas (111/142) there were a total of 161 lesions, attributable to MUP in 64% (103/161), FUP in 15.5% (25/161), and inflammation in 20.5% (33/161). In most placentas of term SGA neonates with normal UA Doppler histological abnormalities secondary to maternal underperfusion prevail, reflecting latent insufficiency in uteroplacental blood supply. This is consistent with the higher risk of adverse perinatal outcome reported in this population and underscores a need for new markers of placental disease. A significant proportion of late-onset SGA births with normal umbilical artery Doppler may still be explained by placental insufficiency. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Comparison of harmonic and conventional power Doppler ultrasonography for assessment of slow flow in hyperechoic tissue: experimental study using a Doppler phantom.

    PubMed

    Kim, A Y; Kim, T K; Kim, Y H; Han, J K; Choi, B I

    2000-02-01

    Despite the advantages of depicting slow flow in small vessels, conventional power Doppler ultrasound (US) has a basic limitation, specifically that artifactual power Doppler signals mimic blood flow, especially in hyperechoic tissue. The purpose of this study was to compare harmonic power Doppler US with power Doppler US using a Doppler phantom under various parameter settings, focusing on the assessment of slow flow in the hyperechoic tissue. While controlling the flow velocity (5 and 10 cm/s), pulse repetition frequency (500, 700, and 1,000 Hz), wall filter (low and medium), and Doppler gain (90%, 96%, and 100%), the authors performed both harmonic Doppler US and power Doppler US by using a Doppler phantom/flow control system. We measured and compared the relative intensities of the Doppler signals (0-250 scale) in both the vessels and hyperechoic tissue-mimicking materials with the two different imaging modalities. Power Doppler US with any combination of the four parameters evaluated depicted strong flow signals (mean, 213) that were superior to harmonic Doppler US (mean, 61). Relatively strong artifactual signals within the hyperechoic tissue-mimicking materials were noted on all power Doppler US studies (mean, 106) but nearly none on harmonic Doppler US (mean, 3). The contrast-to-noise ratio of harmonic Doppler US was significantly greater than that of power Doppler US. Harmonic Doppler US is more useful in assessing slow flow in hyperechoic tissue than power Doppler US because it produces fewer artifactual Doppler signals originating from stationary hyperechoic tissues, which can be misjudged as true signals on power Doppler US.

  18. Rotational Doppler effect in x-ray photoionization

    SciTech Connect

    Sun Yuping; Wang Chuankui; Gel'mukhanov, Faris

    2010-11-15

    The energy of the photoelectron experiences a red or blue Doppler shift when the molecule recedes from the detector or approaches him. This results in a broadening of the photoelectron line due to the translational thermal motion. However, the molecules also have rotational degrees of freedom and we show that the translational Doppler effect has its rotational counterpart. This rotational Doppler effect leads to an additional broadening of the spectral line of the same magnitude as the Doppler broadening caused by translational thermal motion. The rotational Doppler broadening as well as the rotational recoil broadening is sensitive to the molecular orbital from which the photoelectron is ejected. This broadening should be taken into account in analysis of x-ray photoemission spectra of super-high resolution and it can be directly observed using x-ray pump-probe spectroscopy.

  19. Spline function approximation for velocimeter Doppler frequency measurement

    NASA Technical Reports Server (NTRS)

    Savakis, Andreas E.; Stoughton, John W.; Kanetkar, Sharad V.

    1989-01-01

    A spline function approximation approach for measuring the Doppler spectral peak frequency in a laser Doppler velocimeter system is presented. The processor is designed for signal bursts with mean Doppler shift frequencies up to 100 MHz, input turbulence up to 20 percent, and photon counts as low as 300. The frequency-domain processor uses a bank of digital bandpass filters for the capture of the energy spectrum of each signal burst. The average values of the filter output energies, as a function of normalized frequency, are modeled as deterministic spline functions which are linearly weighted to evaluate the spectral peak location associated with the Doppler shift. The weighting coefficients are chosen to minimize the mean square error. Performance evaluation by simulation yields average errors in estimating mean Doppler frequencies within 0.5 percent for poor signal-to-noise conditions associated with a low photon count of 300 photons/burst.

  20. Ultrasound and colour Doppler in infantile subglottic haemangioma.

    PubMed

    Rossler, Leo; Rothoeft, T; Teig, N; Koerner-Rettberg, C; Deitmer, T; Rieger, C H L; Hamelmann, E

    2011-11-01

    Subglottic haemangioma causes progressive and life-threatening stridor, typically manifesting at age 2-3 months. Standard diagnosis is by laryngoscopy. Larynx sonography is rarely used but allows assessment of the presence and extension of a mass that impinges on the subglottic airway. The additional use of colour Doppler enables demonstration of the vascular nature of such masses. To compare US and endoscopic findings in infants with subglottic haemangioma and to evaluate accuracy of US and colour Doppler imaging in this diagnosis. We report eight infants with subglottic haemangioma seen in our institution over the last decade. They presented with laryngeal stridor and were all investigated with both US and endoscopy. Six infants underwent colour Doppler sonography. US and endoscopic findings showed excellent anatomical correlation in lateral subglottic haemangioma. Colour Doppler imaging was deemed helpful in four infants. Larynx sonography with complementary colour Doppler imaging was non-invasive and helpful in the diagnosis of subglottic haemangioma.

  1. One way Doppler extractor. Volume 1: Vernier technique

    NASA Technical Reports Server (NTRS)

    Blasco, R. W.; Klein, S.; Nossen, E. J.; Starner, E. R.; Yanosov, J. A.

    1974-01-01

    A feasibility analysis, trade-offs, and implementation for a One Way Doppler Extraction system are discussed. A Doppler error analysis shows that quantization error is a primary source of Doppler measurement error. Several competing extraction techniques are compared and a Vernier technique is developed which obtains high Doppler resolution with low speed logic. Parameter trade-offs and sensitivities for the Vernier technique are analyzed, leading to a hardware design configuration. A detailed design, operation, and performance evaluation of the resulting breadboard model is presented which verifies the theoretical performance predictions. Performance tests have verified that the breadboard is capable of extracting Doppler, on an S-band signal, to an accuracy of less than 0.02 Hertz for a one second averaging period. This corresponds to a range rate error of no more than 3 millimeters per second.

  2. Doppler-cancelled response to VLF gravitational waves

    NASA Technical Reports Server (NTRS)

    Caporali, A.

    1981-01-01

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

  3. The NLM Indexing Initiative's Medical Text Indexer.

    PubMed

    Aronson, Alan R; Mork, James G; Gay, Clifford W; Humphrey, Susanne M; Rogers, Willie J

    2004-01-01

    The Medical Text Indexer (MTI) is a program for producing MeSH indexing recommendations. It is the major product of NLM's Indexing Initiative and has been used in both semi-automated and fully automated indexing environments at the Library since mid 2002. We report here on an experiment conducted with MEDLINE indexers to evaluate MTI's performance and to generate ideas for its improvement as a tool for user-assisted indexing. We also discuss some filtering techniques developed to improve MTI's accuracy for use primarily in automatically producing the indexing for several abstracts collections.

  4. Effect of metformin treatment on endometrial vascular indices in anovulatory obese/overweight women with polycystic ovarian syndrome using three-dimensional power doppler ultrasonography.

    PubMed

    Mohsen, Iman Abdel; Elkattan, Eman; Nabil, Hala; Khattab, Sherif

    2013-06-01

    Metformin has been shown to be an effective treatment for anovulatory polycystic ovary syndrome (PCOS) patients in terms of menstrual cyclicity, ovulation, and pregnancy, as well as reduction of early miscarriage rate. The aim of the study is to assess the effect of metformin on the endometrial vascular indices in anovulatory obese PCOS women using three-dimensional power Doppler sonography (3DPDUS). A prospective study was set to determine the beneficial effects of metformin on PCOS patients. Fifty anovulatory obese PCOS patients were compared with another 50 healthy volunteers who were age- and body mass index-matched (control group). PCOS patients were treated with metformin (Glucophage; MerckSerono) 850 mg 3 times a day for 6 months. Assessment of the endometrial thickness and volume, uterine Doppler indices, and Doppler vascular indices of the endometrium and subendometrium in the periovulatory and midluteal phases were performed with 3DPDUS. There was a significant increase in the endometrial thickness, endometrial volume, and endometrial and subendometrial vascularity indices (vascularization index, flow index, vascularization flow index) after 6 months of metformin treatment in PCOS women, whereas there was no change in the resistance index and the pulsatility index of the uterine artery in both periovulatory and midluteal phases. Metformin, owing to its metabolic, endocrine, vascular, and anti-inflammatory effects, improves markers of endometrial receptivity. Copyright © 2012 Wiley Periodicals, Inc.

  5. Position finding using simple Doppler sensors

    NASA Astrophysics Data System (ADS)

    Schelkshorn, S.; Detlefsen, J.

    2007-06-01

    An increasing number of modern applications and services is based on the knowledge of the users actual position. Depending on the application a rough position estimate is sufficient, e. g. services in cellular networks that use the information about the users actual cell. Other applications, e. g. navigation systems use the GPS-System for accurate position finding. Beyond these outdoor applications a growing number of indoor applications requires position information. The previously mentioned methods for position finding (mobile cell, GPS) are not usable for these indoor applications. Within this paper we will present a system that relies on the simultaneous measurement of doppler signals at four different positions to obtain position and velocity of an unknown object. It is therefore suiteable for indoor usage, extendig already existing wireless infrastructure.

  6. Microscale Heat Conduction Models and Doppler Feedback

    SciTech Connect

    Hawari, Ayman I.; Ougouag, Abderrafi

    2015-01-22

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

  7. Doppler Global Velocimetry: The Next Generation?

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    1991-01-01

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

  8. Signal Processing Schemes for Doppler Global Velocimetry

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  9. Analytic radar micro-Doppler signatures classification

    NASA Astrophysics Data System (ADS)

    Oh, Beom-Seok; Gu, Zhaoning; Wang, Guan; Toh, Kar-Ann; Lin, Zhiping

    2017-06-01

    Due to its capability of capturing the kinematic properties of a target object, radar micro-Doppler signatures (m-DS) play an important role in radar target classification. This is particularly evident from the remarkable number of research papers published every year on m-DS for various applications. However, most of these works rely on the support vector machine (SVM) for target classification. It is well known that training an SVM is computationally expensive due to its nature of search to locate the supporting vectors. In this paper, the classifier learning problem is addressed by a total error rate (TER) minimization where an analytic solution is available. This largely reduces the search time in the learning phase. The analytically obtained TER solution is globally optimal with respect to the classification total error count rate. Moreover, our empirical results show that TER outperforms SVM in terms of classification accuracy and computational efficiency on a five-category radar classification problem.

  10. Cyclotron maser using the anomalous Doppler effect

    NASA Astrophysics Data System (ADS)

    Didenko, A. N.; Borisov, A. R.; Fomenko, G. P.; Shlapakovskii, A. S.; Shtein, Iu. G.

    1983-11-01

    The operation of an anomalous-Doppler-effect cyclotron-resonance maser using a waveguide partially filled with dielectric as the slow-wave system is reported. The device investigated is similar to that of Didenko et al. (1983) and comprises a 300-mm-long 50-mm-o.d. 30-mm-i.d. waveguide with fabric-laminate dielectric, located 150 mm from the cathode in a 500-mm-long region of uniform 0-20-kG magnetic field, and a coaxial magnetic-insulation gun producing a 13-mm-i.d. 25-mm-o.d. hollow electron beam. Radiation at 12 + or - 1 mm wavelength and optimum power 20 MW is observed using hot-carrier detectors, with a clear peak in the power-versus-magnetic-field curve at about 6.4 kG.

  11. Spacecraft Doppler tracking with a VLBI antenna

    NASA Astrophysics Data System (ADS)

    Comoretto, G.; Iess, L.; Bertotti, B.; Brenkle, J. P.; Horton, T.

    1990-02-01

    Preliminary results are reported from Doppler-shift measurements to the Voyager-2 spacecraft at a distance of 26 AU, obtained using the 32-m VLBI antenna at Medicina (Italy) during July and August 1988. The apparatus comprises the el-az antenna, an S-X-band receiver, a hydrogen maser to generate the reference signal, a Mark III VLBI terminal, and a digital tone extractor capable of isolating a tone of known frequency from a noisy signal and giving its phase and amplitude. A signal transmitted in S-band from the NASA Deep Space Network (DSN) station in Australia and retransmitted coherently in X-band by Voyager, was received 7 h 6 min later at Medicina and at the DSN station in Madrid. Sample data are presented graphically and shown to be of generally high quality; further in-depth analysis is under way.

  12. Spacecraft Doppler tracking with a VLBI antenna

    NASA Technical Reports Server (NTRS)

    Comoretto, G.; Iess, L.; Bertotti, B.; Brenkle, J. P.; Horton, T.

    1990-01-01

    Preliminary results are reported from Doppler-shift measurements to the Voyager-2 spacecraft at a distance of 26 AU, obtained using the 32-m VLBI antenna at Medicina (Italy) during July and August 1988. The apparatus comprises the el-az antenna, an S-X-band receiver, a hydrogen maser to generate the reference signal, a Mark III VLBI terminal, and a digital tone extractor capable of isolating a tone of known frequency from a noisy signal and giving its phase and amplitude. A signal transmitted in S-band from the NASA Deep Space Network (DSN) station in Australia and retransmitted coherently in X-band by Voyager, was received 7 h 6 min later at Medicina and at the DSN station in Madrid. Sample data are presented graphically and shown to be of generally high quality; further in-depth analysis is under way.

  13. The generalized Doppler effect for surface waves

    NASA Astrophysics Data System (ADS)

    Michel, G.

    2016-11-01

    We investigate energy exchanges through scales occurring when a surface wave reflects on a harmonically oscillating wall. We first experimentally evidence the creation of Doppler-shifted waves and measure their height as a function of the oscillation amplitude. Then, we theoretically compute the amplitudes of these new waves in the gravity regime. Both results show that even without bulk non-linearities, oscillating paddles in a fluid container lead to a complex wave energy spectrum competing with the one predicted by wave turbulence. To exemplify this point, we characterize a simple one-dimensional model consisting of a linear wave equation in an oscillating cavity with distinct injection and dissipation mechanisms. It displays features usually associated with non-linearities, as self-similarity in a spectral domain (the so-called inertial range), appearance of energy at larger and/or lower scales than the forcing one and creation of shock waves.

  14. NEXRAD - An advanced Doppler weather radar system

    NASA Astrophysics Data System (ADS)

    Durham, A. F.

    The WSR-57 system, which was first placed into operation in 1957, forms the backbone of the current radar observation network of the National Weather Service. However, in connection with its age, it has become increasingly difficult and expensive to maintain this system. The present investigation is concerned with the replacement of the WSR-57 by a new system which incorporates important advances made in radar technology since the 1950s. The new system considered, called the Next Generation Weather Radar (NEXRAD) makes use of highly automated Doppler techniques to measure the radial velocity of air movement within the internal structure of a storm system. Attention is given to background regarding the NEXRAD system development, the four phases of the NEXRAD program, NEXRAD system capabilities, operational (display) products, and questions of siting.

  15. Laser Doppler vibrometry: new ENT applications

    NASA Astrophysics Data System (ADS)

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

    1996-12-01

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

  16. The Christian Doppler Laboratory on Contextual Interfaces

    NASA Astrophysics Data System (ADS)

    Grill, Thomas; Reitberger, Wolfgang; Obrist, Marianna; Meschtscherjakov, Alexander; Tscheligi, Manfred

    Contextual interfaces gain more and more importance within the last years. Numerous research programs that address the term context have been established, each focusing on context from their own point of view. The Christian Doppler Laboratory on Contextual Interfaces has been founded with different goals in mind. The first goal is to elaborate on the definitions and foundations of the term context to achieve a common understanding on how to use context and the terms related to context. Further we elaborate on the relation between context and user experience to tackle the complexity of the interrelations between both areas. The second goal is to apply the findings of the basic context research with two different context laboratories, each addressing a different application area. This allows to build a robust research basis that is applied to application oriented research.

  17. Laser Doppler vibrometer employing active frequency feedback.

    PubMed

    Chijioke, Akobuije; Lawall, John

    2008-09-20

    We present a heterodyne Michelson interferometer for vibration measurement in which feedback is used to obviate the need to unwrap phase data. The Doppler shift of a vibrating target mirror is sensed interferometrically and compensated by means of a voltage-controlled oscillator driving an acousto-optic modulator. For frequencies within the servo bandwidth, the oscillator control voltage provides a direct measurement of the target velocity. Outside the servo bandwidth, phase-sensitive detection is used to evaluate high-frequency displacements. This approach is of great interest for the frequently-occurring situation where vibration amplitudes at low frequency exceed an optical wavelength, but knowledge of the vibration spectrum at high frequency is important as well.

  18. Hands-Free Transcranial Color Doppler Probe

    NASA Technical Reports Server (NTRS)

    Chin, Robert; Madala, Srihdar; Sattler, Graham

    2012-01-01

    Current transcranial color Doppler (TCD) transducer probes are bulky and difficult to move in tiny increments to search and optimize TCD signals. This invention provides miniature motions of a TCD transducer probe to optimize TCD signals. The mechanical probe uses spherical bearing in guiding and locating the tilting crystal face. The lateral motion of the crystal face as it tilts across the full range of motion was achieved by minimizing the distance between the pivot location and the crystal face. The smallest commonly available metal spherical bearing was used with an outer diameter of 12 mm, a 3-mm tall retaining ring, and 5-mm overall height. Small geared motors were used that would provide sufficient power in a very compact package. After confirming the validity of the basic positioning concept, optimization design loops were completed to yield the final design.

  19. Spacecraft Doppler tracking with a VLBI antenna

    NASA Technical Reports Server (NTRS)

    Comoretto, G.; Iess, L.; Bertotti, B.; Brenkle, J. P.; Horton, T.

    1990-01-01

    Preliminary results are reported from Doppler-shift measurements to the Voyager-2 spacecraft at a distance of 26 AU, obtained using the 32-m VLBI antenna at Medicina (Italy) during July and August 1988. The apparatus comprises the el-az antenna, an S-X-band receiver, a hydrogen maser to generate the reference signal, a Mark III VLBI terminal, and a digital tone extractor capable of isolating a tone of known frequency from a noisy signal and giving its phase and amplitude. A signal transmitted in S-band from the NASA Deep Space Network (DSN) station in Australia and retransmitted coherently in X-band by Voyager, was received 7 h 6 min later at Medicina and at the DSN station in Madrid. Sample data are presented graphically and shown to be of generally high quality; further in-depth analysis is under way.

  20. Widefield laser doppler velocimeter: development and theory.

    SciTech Connect

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

    2007-03-01

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

  1. Doppler cooling and trapping on forbidden transitions.

    PubMed

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

    2001-09-17

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

  2. Doppler interpretation of quasar red shifts.

    PubMed

    Zapolsky, H S

    1966-08-05

    The hypothesis that the quasistellar sources (quasars) are local objects moving with velocities close to the speed of light is examined. Provided there is no observational cutoff on apparent bolometric magnitude for the quasars, the transverse Doppler effect leads to the expectation of fewer blue shifts than red shifts for an isotropic distribution of velocities. Such a distribution also yields a function N(z), the number of objects with red shift less than z which is not inconsistent with the present data. On the basis of two extreme assumptions concerning the origin of such rapidly moving sources, we computed curves of red shift plotted against magnitude. In particular, the curve obtained on the assumption that the quasars originated from an explosion in or nearby our own galaxy is in as good agreement with the observations as the curve of cosmological red shift plotted against magnitude.

  3. [Use of laser Doppler flowmetry in dentistry].

    PubMed

    Roeykens, H; Nammour, S; De Moor, R

    2009-01-01

    An early determination of pulpal vitality is crucial with respect to a correct differential diagnosis of revascularisation or necrosis and its treatment. The use of sensibility tests (cold, heat, electrical pulp test) in combination with X-ray are commonly promoted. However these tests are arbitrary, based on sensations and therefore not always reliable. In such situation the registration of 'real' pulpal blood flow and hence pulp vitality will be more than an added value. The most studied and well documented method is laser Doppler flowmetry (LDF) as it is non invasive, direct and objective. In this article we describe blood flow, LDF and its characteristics, advantages and disadvantages of this method and the newest developments regarding LDF. Despite a low implementation of LDF in Belgium, this technique proved to belong indisputable to the basic assets of a dental clinic. A number of cases are described to demonstrate the efficacy and added value of LDF in assessing tooth vitality.

  4. DC coupled Doppler radar physiological monitor.

    PubMed

    Zhao, Xi; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

    2011-01-01

    One of the challenges in Doppler radar systems for physiological monitoring is a large DC offset in baseband outputs. Typically, AC coupling is used to eliminate this DC offset. Since the physiological signals of interest include frequency content near DC, it is not desirable to simply use AC coupling on the radar outputs. While AC coupling effectively removes DC offset, it also introduces a large time delay and distortion. This paper presents the first DC coupled IQ demodulator printed circuit board (PCB) design and measurements. The DC coupling is achieved by using a mixer with high LO to RF port isolation, resulting in a very low radar DC offset on the order of mV. The DC coupled signals from the PCB radar system were successfully detected with significant LNA gain without saturation. Compared to the AC coupled results, the DC coupled results show great advantages of less signal distortion and more accurate rate estimation.

  5. Processing of the laser Doppler velocimeter signals

    NASA Technical Reports Server (NTRS)

    Meyers, J. F.; Feller, W. V.

    1973-01-01

    The laser Doppler velocimeter (LDV) is a probeless technique that provides a remote measurement of mean and fluctuating velocities. The measurement is actually obtained from small particles embedded in the flow which scatter light from an illuminating laser beam interference pattern. A portion of this scattered light is collected by a photomultiplier which yields an electronic signal whose frequency is directly proportional to the velocity of the small particles. The purpose of this paper is to describe and critically compare three techniques most used to process this electronic signal. These techniques are: (1) spectrum analyzer - a frequency scanning filter (frequency domain instrument), (2) wide-band frequency tracker - a frequency lock loop (frequency domain instrument), and (3) high-speed frequency counter - an interval timer (time domain instrument). The study determines the ability of each technique to process the LDV signal and yield velocity data to be used in determining the flow characteristics.

  6. Phase Doppler anemometry as an ejecta diagnostic

    NASA Astrophysics Data System (ADS)

    Bell, D. J.; Chapman, D. J.

    2017-01-01

    When a shock wave is incident on a free surface, micron sized pieces of the material can be ejected from that surface. Phase Doppler Anemometry (PDA) is being developed to simultaneously measure the sizes and velocities of the individual shock induced ejecta particles; providing an important insight into ejecta phenomena. The results from experiments performed on the 13 mm bore light gas gun at the Institute of Shock Physics, Imperial College London are presented. Specially grooved tin targets were shocked at pressures of up to 14 GPa, below the melt on release pressure, to generate ejecta particles. These experiments are the first time that PDA has been successfully fielded on dynamic ejecta experiments. The results and current state of the art of the technique are discussed along with the future improvements required to optimise performance and increase usability.

  7. Wind Field Measurements With Airborne Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.

    1999-01-01

    In collaboration with lidar atmospheric remote sensing groups at NASA Marshall Space Flight Center and National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory, we have developed and flown the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) lidar on the NASA DC-8 research aircraft. The scientific motivations for this effort are: to obtain measurements of subgrid scale (i.e. 2-200 km) processes and features which may be used to improve parameterizations in global/regional-scale models; to improve understanding and predictive capabilities on the mesoscale; and to assess the performance of Earth-orbiting Doppler lidar for global tropospheric wind measurements. MACAWS is a scanning Doppler lidar using a pulsed transmitter and coherent detection; the use of the scanner allows 3-D wind fields to be produced from the data. The instrument can also be radiometrically calibrated and used to study aerosol, cloud, and surface scattering characteristics at the lidar wavelength in the thermal infrared. MACAWS was used to study surface winds off the California coast near Point Arena, with an example depicted in the figure below. The northerly flow here is due to the Pacific subtropical high. The coastal topography interacts with the northerly flow in the marine inversion layer, and when the flow passes a cape or point that juts into the winds, structures called "hydraulic expansion fans" are observed. These are marked by strong variation along the vertical and cross-shore directions. The plots below show three horizontal slices at different heights above sea level (ASL). Bottom plots are enlargements of the area marked by dotted boxes above. The terrain contours are in 200-m increments, with the white spots being above 600-m elevation. Additional information is contained in the original.

  8. Myocardial Tissue Doppler Velocity in Child Growth

    PubMed Central

    Choi, Sun-Ha; Kim, Nam Kyun; Jung, Jo Won; Choi, Jae Young

    2016-01-01

    Background In adults, tissue Doppler imaging (TDI) is a recommended component of routine echocardiography. However, TDI velocities are less accepted in pediatrics, due to their strong variability and age dependence in children. This study examines the distribution of myocardial tissue Doppler velocities in healthy children to assess the effect of age with cardiac growth on the various echocardiographic measurements. Methods Total 144 healthy children were enrolled in this study. They were recruited from the pediatric outpatient clinic for routine well-child visits. The statistical relationships between age and TDI values were analyzed. Also, the statistical relationships between body surface area (BSA) and TDI values, left ventricle end-diastolic dimension (LVEDD) and TDI values were analyzed. Also, we conducted multivariate analysis of cardiac growth parameters such as, age, BSA, LVEDD and TDI velocity data. Results All of the age, BSA, and LVEDD had positive correlations with deceleration time (DT), pressure half-time (PHT), peak early diastolic myocardial velocity, peak systolic myocardial velocity, and had negative correlations with peak late diastolic velocity (A) and the ratio of trans-mitral inflow velocity to early diastolic velocity of mitral annulus (E/E'). In the multivariate analysis, all of the age, BSA, and LVEDD had positive correlations with DT, PHT, and negative correlations with A and E/E'. Conclusion The cardiac growth parameters related alterations of E/E' may suggest that diastolic myocardial velocities are cardiac growth dependent, and diastolic function has positive correlation with cardiac growth in pediatric group. This cardiac growth related myocardial functional variation would be important for assessment of cardiac involvement either in healthy and sick child. PMID:27081443

  9. Laser Doppler flowmetry in endodontics: a review.

    PubMed

    Jafarzadeh, H

    2009-06-01

    Vascular supply is the most accurate marker of pulp vitality. Tests for assessing vascular supply that rely on the passage of light through a tooth have been considered as possible methods for detecting pulp vitality. Laser Doppler flowmetry (LDF), which is a noninvasive, objective, painless, semi-quantitative method, has been shown to be reliable for measuring pulpal blood flow. The relevant literature on LDF in the context of endodontics up to March 2008 was reviewed using PubMed and MEDLINE database searches. This search identified papers published between June 1983 and March 2008. Laser light is transmitted to the pulp by means of a fibre optic probe. Scattered light from moving red blood cells will be frequency-shifted whilst that from the static tissue remains unshifted. The reflected light, composed of Doppler-shifted and unshifted light, is returned by afferent fibres and a signal is produced. This technique has been successfully employed for estimating pulpal vitality in adults and children, differential diagnosis of apical radiolucencies (on the basis of pulp vitality), examining the reactions to pharmacological agents or electrical and thermal stimulation, and monitoring of pulpal responses to orthodontic procedures and traumatic injuries. Assessments may be highly susceptible to environmental and technique-related factors. Nonpulpal signals, principally from periodontal blood flow, may contaminate the signal. Because this test produces no noxious stimuli, apprehensive or distressed patients accept it more readily than current methods of pulp vitality assessment. A review of the literature and a discussion of the application of this system in endodontics are presented.

  10. Effects of transducer beam geometry and flow velocity profile on the Doppler power spectrum: a theoretical study.

    PubMed

    Bascom, P A; Cobbold, R S

    1990-01-01

    A theoretical model is used to show how the Doppler spectrum for various axisymmetric velocity profiles is affected by beam misalignment and incomplete insonation. Results are presented for both circular and square beam geometries. Moreover, a closed-form expression is derived for the power spectral density received by an on-axis transducer with a Gaussian beam profile. It is shown that the error incurred in measuring the mean Doppler frequency with such a profile will generally be bounded by the results for the circular and square beam geometries. The effects of an ideal high-pass filter on the mean Doppler frequency and the backscattered Doppler power are examined. It is shown that such a filter can introduce large differences in the measured systolic to diastolic power ratios. Finally, theoretical expressions and results are presented for the spectral broadening index (SBI), normalized spectral variance (NSV), coefficient of kurtosis (CK), the coefficient of skewness (CS) as functions of the axisymmetric velocity profile shape assuming complete uniform insonation.

  11. Effect of ensemble averaging on amplitude and feature variabilities of Doppler spectrograms recorded in the lower limb arteries.

    PubMed

    Allard, L; Langlois, Y E; Durand, L G; Roederer, G O; Cloutier, G

    1992-05-01

    The objective of the present study was to analyse the effect of averaging Doppler blood flow signals in lower limb arteries on amplitude and feature variabilities. Doppler signals recorded in 41 iliac and 35 superficial femoral arteries having different categories of stenosis were averaged over 1-15 cardiac cycles. Based on the relative decreasing rate of an index of variability, results indicated that amplitude variability of the spectrograms was exponentially reduced to 30, 6 and 1 per cent when averaging five, ten and 15 cardiac cycles, respectively. Nine diagnostic features were extracted from Doppler spectrograms and their variations from one cardiac cycle to the next quantified. Based on the relative decreasing rate of these variations, results indicated that feature variability was exponentially reduced to 30, 4 and 1 per cent when averaging five, ten and 15 cardiac cycles, respectively. The effect of averaging on the discriminant power of the features to separate the different categories of stenosis was also investigated by performing t-test analyses. Results showed that averaging between five and ten cardiac cycles provided the better discriminant power for most cases, whereas averaging over more than ten cardiac cycles was of little benefit. Based on the spectral analysis technique used in the present study, we conclude that averaging over ten cardiac cycles is sufficient for the analysis of Doppler spectrograms recorded in the lower limbs.

  12. Comparison of time-frequency distribution techniques for analysis of simulated Doppler ultrasound signals of the femoral artery.

    PubMed

    Guo, Z; Durand, L G; Lee, H C

    1994-04-01

    The time-frequency distribution of the Doppler ultrasound blood flow signal is normally computed by using the short-time Fourier transform or autoregressive modeling. These two techniques require stationarity of the signal during a finite interval. This requirement imposes some limitations on the distribution estimate. In the present study, three new techniques for nonstationary signal analysis (the Choi-Williams distribution, a reduced interference distribution, and the Bessel distribution) were tested to determine their advantages and limitations for analysis of the Doppler blood flow signal of the femoral artery. For the purpose of comparison, a model stimulating the quadrature Doppler signal was developed, and the parameters of each technique were optimized based on the theoretical distribution. Distributions computed using these new techniques were assessed and compared with those computed using the short-time Fourier transform and autoregressive modeling. Three indexes, the correlation coefficient, the integrated squared error, and the normalized root-mean-squared error of the mean frequency waveform, were used to evaluate the performance of each technique. The results showed that the Bessel distribution performed the best, but the Choi-Williams distribution and autoregressive modeling are also techniques which can generate good time-frequency distributions of Doppler signals.

  13. [Usefulness of natriuretic peptide testing and Doppler echocardiography at bedside in the diagnosis of acute heart failure].

    PubMed

    Arques, S; Roux, E

    2016-11-01

    Acute heart failure is a common condition that leads to hospital admission, with important mortality and readmission rates. A prompt and accurate diagnosis of this condition by hospitalists is essential for an early and tailored medical management. The use of natriuretic peptide testing (BNP and NT-proBNP) through a two cut-point strategy is currently recommended as the first-line diagnostic complement to the initial clinical evaluation in the acute care setting. Transthoracic Doppler echocardiography is an other noninvasive method that can be used at bedside, especially in patients with intermediate, inconclusive natriuretic peptides levels. In this regard, left ventricular ejection fraction and several simple Doppler indexes (restrictive mitral filling pattern, spectral tissue Doppler E/e' ratio), have been validated in the emergency diagnosis of acute heart failure. The aim of the present review is to overview the respective contribution of natriuretic peptides and Doppler echocardiography at bedside to the diagnosis of acute heart failure in the acute care setting.

  14. Noninvasive color Doppler sonography of uterine blood flow throughout pregnancy in sheep and goats.

    PubMed

    Elmetwally, M; Rohn, K; Meinecke-Tillmann, S

    2016-04-01

    In contrast to cattle or horses, uterine blood flow in small ruminants has been investigated predominantly after surgical intervention and chronic instrumentation. The objective of the present study was to investigate the clinical applicability of noninvasive color Doppler sonography to characterize blood flow in the maternal uterine artery of sheep, n = 11 (18 pregnancies) and goats, n = 11 (20 pregnancies). The following parameters were measured transrectally or transabdominally: blood flow volume, time-averaged maximum velocity (TAMV), resistance index (RI), pulsatility index (PI), Time-averaged mean velocity, impedance of blood flow (AB or systolic/diastolic [S/D] velocity ratio), peak velocity of blood flow and blood flow acceleration. Examinations started 2 weeks after breeding and continued at 2-week intervals until parturition. Outcomes for sheep and goats were similar and will be discussed together. Based on noninvasive color Doppler sonography, blood flow volume increased (approximately 60-fold, P < 0.0001) until the end of pregnancy, with a rapid increase early in gestation, and a slow increase after week 18. Time-averaged maximum velocity in the uterine artery increased (approximately 4-fold; P < 0.0001) throughout pregnancy in sheep and goats. Furthermore, for uterine artery blood flow, there was an effect of stage of pregnancy on PI and RI (P < 0.001 and P < 0.0001, respectively), both indices decreased until the end of gestation. Time-averaged mean velocity decreased from week 18 to 20 in both species. The blood flow acceleration increased (P < 0.0001) until week 16 and week 14 in sheep and goats, respectively, and then decreased until parturition. Similar to PI and RI, vascular impedance of the uterine decreased (P < 0.0001) throughout pregnancy. This is apparently the first study using noninvasive color Doppler sonography of uterine blood flow throughout physiological pregnancy in small ruminants. Clearly, this technology facilitates repeated

  15. Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction

    PubMed Central

    Hodges, Ryan; Endo, Masayuki; La Gerche, Andre; Eixarch, Elisenda; DeKoninck, Philip; Ferferieva, Vessilina; D'hooge, Jan; Wallace, Euan M.; Deprest, Jan

    2013-01-01

    Fetal intrauterine growth restriction (IUGR) results in abnormal cardiac function that is apparent antenatally due to advances in fetoplacental Doppler ultrasound and fetal echocardiography. Increasingly, these imaging modalities are being employed clinically to examine cardiac function and assess wellbeing in utero, thereby guiding timing of birth decisions. Here, we used a rabbit model of IUGR that allows analysis of cardiac function in a clinically relevant way. Using isoflurane induced anesthesia, IUGR is surgically created at gestational age day 25 by performing a laparotomy, exposing the bicornuate uterus and then ligating 40-50% of uteroplacental vessels supplying each gestational sac in a single uterine horn. The other horn in the rabbit bicornuate uterus serves as internal control fetuses. Then, after recovery at gestational age day 30 (full term), the same rabbit undergoes examination of fetal cardiac function. Anesthesia is induced with ketamine and xylazine intramuscularly, then maintained by a continuous intravenous infusion of ketamine and xylazine to minimize iatrogenic effects on fetal cardiac function. A repeat laparotomy is performed to expose each gestational sac and a microultrasound examination (VisualSonics VEVO 2100) of fetal cardiac function is performed. Placental insufficiency is evident by a raised pulsatility index or an absent or reversed end diastolic flow of the umbilical artery Doppler waveform. The ductus venosus and middle cerebral artery Doppler is then examined. Fetal echocardiography is performed by recording B mode, M mode and flow velocity waveforms in lateral and apical views. Offline calculations determine standard M-mode cardiac variables, tricuspid and mitral annular plane systolic excursion, speckle tracking and strain analysis, modified myocardial performance index and vascular flow velocity waveforms of interest. This small animal model of IUGR therefore affords examination of in utero cardiac function that is

  16. Compressed Sensing Doppler Ultrasound Reconstruction Using Block Sparse Bayesian Learning.

    PubMed

    Lorintiu, Oana; Liebgott, Herve; Friboulet, Denis

    2016-04-01

    In this paper we propose a framework for using duplex Doppler ultrasound systems. These type of systems need to interleave the acquisition and display of a B-mode image and of the pulsed Doppler spectrogram. In a recent study (Richy , 2013), we have shown that compressed sensing-based reconstruction of Doppler signal allowed reducing the number of Doppler emissions and yielded better results than traditional interpolation and at least equivalent or even better depending on the configuration than the study estimating the signal from sparse data sets given in Jensen, 2006. We propose here to improve over this study by using a novel framework for randomly interleaving Doppler and US emissions. The proposed method reconstructs the Doppler signal segment by segment using a block sparse Bayesian learning (BSBL) algorithm based CS reconstruction. The interest of using such framework in the context of duplex Doppler is linked to the unique ability of BSBL to exploit block-correlated signals and to recover non-sparse signals. The performance of the technique is evaluated from simulated data as well as experimental in vivo data and compared to the recent results in Richy , 2013.

  17. Clinical Applications of Doppler OCT and OCT Angiography

    NASA Astrophysics Data System (ADS)

    Tan, Ou; Jia, Yali; Wei, Eric; Huang, David

    Doppler optical coherence tomography (OCT) is a functional extension of OCT that allows for the visualization and measurement of blood flow [1, 2]. Phase-resolved Doppler OCT has become a standard algorithm for measuring Doppler shift with Fourier-domain (FD)-OCT because of its high velocity sensitivity [3]. In ophthalmology, several methods have been developed to measure in vivo retinal blood flow using this algorithm. Since Doppler OCT measures only the velocity component parallel to the OCT probe beam, additional information is needed to calculate absolute velocity and volumetric flow rate. One method is to employ two OCT beams with a fixed offset in incidence angles [4, 5]. However, this approach requires special hardware and is not compatible with commercial single-beam OCT systems. Another approach is to use special scan patterns to measure the Doppler angle (angle between the OCT beam and the blood vessel). Some groups used concentric scan patterns [6, 7], while other groups used raster scan patterns [8, 9]. Finally, Srinivasan et al. developed en face Doppler OCT for cerebral blood flow calculation, which obviated the need for Doppler angle estimation [10]. Bauman et al. adapted the method for total retinal blood flow (TRBF) calculation with ultrafast swept-source OCT [11]. In this chapter, we focus our attention on the double-circular scan pattern developed in our research group, which has been used in a number of clinical studies for preliminary demonstration of utility.

  18. Doppler sensitivity and its effect on transatlantic TWSTFT links

    NASA Astrophysics Data System (ADS)

    Zhang, Shengkang; Parker, Thomas; Zhang, Victor

    2017-02-01

    Some investigations have concluded that the diurnal pattern in the time comparison results of present two way satellite time and frequency transfer (TWSTFT) links may come mainly from Doppler dependent errors in the time of arrival (TOA) measurements made by the receivers of the TWSTFT modems. In this paper, several experiments were carried out to test if there is a Doppler dependent error in the ‘delay’ measurements of the receivers currently used. By simulating quantitative Doppler effects in the time transfer signal both on the carrier and the code, a type of Doppler sensitivity on the code was observed in the receivers, which has about  -0.49 ns offset in ‘delay’ measurement for a 1  ×  10-9 fractional Doppler shift. This sensitivity is basically the same for modems with different serial numbers from the same manufacture. We calculated this Doppler caused diurnal pattern in the time comparison results of the transatlantic TWSTFT link between NIST and PTB and found that it is very small and negligible, because the Doppler dependent error is almost identical in the NIST and PTB measurements and therefore it is nearly canceled in the TWSTFT difference. Commercial products are identified for technical completeness only, and no endorsement by NIST is implied.

  19. Transdermal hormone replacement therapy and Doppler findings in normal and overweight postmenopausal patients.

    PubMed

    Persico, N; Mancini, F; Artini, P G; Regnani, G; Volpe, A; de Aloysio, D; Battaglia, C

    2004-11-01

    The aim of this study was to evaluate the effects of transdermal hormone replacement therapy on some biological cardiovascular risk factors, specifically the thromboxane B2 levels, plasma viscosity and the lipid profile. Furthermore, we investigated the Doppler flow modifications at the level of the uterine artery, the internal carotid, the ophthalmic and the bladder wall arteries, and we finally evaluated whether there were significant differences in the examined parameters between normal and overweight postmenopausal women. Forty-five postmenopausal women (mean age+/-standard deviation, 53.5+/-3.8 years) participated in the study and were divided into two groups (27 with a body mass index of < 25 kg/m2 and 18 with a body mass index of > 25 kg/m2). Patients were treated with a continous estradiol transdermal supplement and a 12-day course of medroxyprogesterone acetate every 2 months, and were studied at baseline and after 6 months (in the estrogen-only phase of the second cycle). Our results showed a beneficial effect of hormone substitution on plasma viscosity, thromboxane B2 levels and lipid profile after 6 months of therapy and significant improvements of Doppler flow parameters in the examined vessels. Furthermore, we observed a lower impact of the treatment in overweight women. In conclusion, obesity represents an additional cardiovascular risk condition and it can only partially be modified by the administration of hormone replacement therapy.

  20. Vascular waveform analysis of flap-feeding vessels using color Doppler ultrasonography.

    PubMed

    Ogino, Akihiro; Onishi, Kiyoshi

    2014-01-01

    We performed vascular waveform analysis of flap-feeding vessels using color Doppler ultrasonography and evaluated the blood flow in the flaps prior to surgery. Vascular waveform analysis was performed in 19 patients. The analyzed parameters included the vascular diameter, flow volume, flow velocity, resistance index, pulsatility index, and acceleration time. The arterial waveform was classified into 5 types based on the partially modified blood flow waveform classification reported by Hirai et al.; in particular, D-1a, D-1b, and D-2 were considered as normal waveforms. They were 4 patients which observed abnormal vascular waveform among 19 patients (D-4 : 1, D-3 : 1, and Poor detect : 2). The case which presented D-4 waveform changed the surgical procedure, and a favorable outcome was achieved. Muscle flap of the case which presented D-3 waveform was partially necrosed. The case which detected blood flow poorly was judged to be the vascular obstruction of the internal thoracic artery. In the evaluation of blood flow in flaps using color Doppler ultrasonography, determination of not only basic blood flow information, such as the vascular distribution and diameter and flow velocity, but also the flow volume, vascular resistance, and arterial waveform is essential to elucidate the hemodynamics of the flap.