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Echocardiographic Doppler measurements of blood flow velocity are a noninvasive way of studying maternal central haemodynamics. Part 1 reports on conditions as well as on practical and theoretical problems recognized as contributing significantly to the use and interpretation of Doppler ultrasound techniques in the assessment of adaptive central circulatory regulation in pregnancy. The significance of different techniques is shown by assessments of the peak velocity and the velocity time integral.

In this work, we provide a computational study of the effects of carotid endarterectomy (CEA) on the fluid-dynamics at internal carotid bifurcations. We perform numerical simulations in real geometries of the same patients before and after CEA, using patient-specific boundary data obtained by Echo-Color Doppler measurements. We analyze four patients with a primary closure and other four where a patch was used to close arteriotomies. The results show that (i) CEA is able to restore physiological fluid-dynamic conditions; (ii) among the post-operative cases, the presence of patch leads to local hemodynamic conditions which might imply a higher risk of restenosis in comparison with the cases without patch.

Background. Long-term graft patency is the major factor impacting survival after coronary artery bypass grafting. Arteries are superior in this regard. Radial artery is considered the second best conduit after internal mammary artery. Several studies have shown excellent radial artery patency. We evaluated the morphologic characteristics of radial artery by three modalities, (i) preoperative Doppler ultrasound, (ii) intraoperative manual morphometry, and (iii) postoperative histology-based morphometry, and compared these with the aim of validating Doppler as a noninvasive test of choice for preoperative assessment of radial artery.Methods. This was a prospective study involving 100 patients undergoing coronary artery bypass grafting in which radial artery was used. The radial artery was assessed using preoperative Doppler ultrasound studies, intraoperative morphometry, and postoperative histopathology and morphometry. The morphometric measurements included (i) luminal diameter, (ii) intimal and medial thickness, and (iii) intima-media thickness ratio.Results. Using Bland-Altman plots, there was a 95% limit of agreement between the preoperative Doppler measurements and the postoperative histopathology and morphometry.Conclusion. Doppler ultrasound is an accurate screening test for evaluation of radial artery, in terms of intimal/medial thickness and luminal diameter as a conduit in coronary artery bypass grafting and has been validated by both morphometric and histopathology based studies.

Assessment of Left Atrial Ejection Force in Patients with different Grades of Left Ventricular Diastolic Dysfunction Objective: To assess left atrial ejection force (LAEF) in patients with different grades of left ventricular (LV) diastolic dysfunction compared to traditional Doppler and tissue Doppler measurements. Methods: 120 patients enrolled into four equal groups (n=30), each group represented a different grade of LV diastolic dysfunction and 30 subjects with normal diastolic function. We assessed echocardiographic measurements of dimensions and diastolic function, LA volume index (LAVI), and LAEF and age-corrected %LAEF. Results: In comparison to control subjects, the study group had more diabetic and hypertensive patients, increased all LV dimensions, estimated LVEDP (p

Sonographic guidelines have been provided for assessing lymph nodes both in the axilla and other areas of the body. The objective of this study was to determine the feasibility of using sonography and Doppler to provide diagnostic nodal information for women 55 years and older. The authors conducted a retrospective longitudinal study of a group of women 55 years and older who provided their prior health histories, mammography, and sonogram results, as well as eventual pathology reports, to help establish the value of Doppler measurements, nodal dimensions, and subjective assessment data collected at the time of the breast sonogram. Each patient consented to allow 15 minutes of scanning of her axilla to evaluate three lymph nodes. Fifty-two women provided data points that were captured and compared to published guidelines, such as longitudinal/diameter (L/D) ratio, resistive index (RI), and Stavros's subjective grading scale. The longitudinal axis compared to the diameter of a node (L/D ratio), shape, and RI was statistically correlated with published guidelines. Sonographic measures and Doppler assessment of axillary lymph nodes are feasible, and continued research could result in a reliable set of parameters that could be used as an economical, noninvasive imaging technique for possible staging of women 55 years and older.

We report precision Doppler measurements of three intermediate-mass subgiants from Lick and Keck Observatories. All three stars show variability in their radial velocities consistent with planet-mass companions in Keplerian orbits. We find a planet with a minimum mass of 2.5 Mjup in a 351.5 day orbit around HD 192699, a planet with a minimum mass of 2.0 Mjup in a 341.1 day orbit around HD 210702, and a planet with a minimum mass of 0.61 Mjup in a 297.3 day orbit around HD 175541. Stellar mass estimates from evolutionary models indicate that all of these stars were formerly A-type dwarfs with masses ranging from 1.65 to 1.85 Msun. These three long-period planets would not have been detectable during their stars' main-sequence phases due to the large rotational velocities and stellar jitter exhibited by early-type dwarfs. There are now 9 "retired" (evolved) A-type stars (Mstar > 1.6 Msun) with known planets. All 9 planets orbit at distances a \geq 0.78 AU, which is significantly different than the semimajor axis distribution of planets around lower-mass stars. We examine the possibility that the observed lack of close-in planets is due to engulfment by their expanding host stars, but we find that this explanation is inadequate given the relatively small stellar radii of K giants (Rstar < 32 Rsun = 0.15 AU) and subgiants (Rstar < 7 Rsun = 0.03 AU). Instead, we conclude that planets around intermediate-mass stars reside preferentially beyond ~0.8 AU, which may be a reflection of different formation and migration histories of planets around A-type stars., 31 pages, 9 figures, 6 tables, ApJ accepted, corrected minor typos

Intra uterine growth retardation is a major cause of perinatal morbidity and mortality. These are due to prolonged intra uterine hypoxia and complications from subsequent induced prematurity. Fetal arterial doppler measurements, and more recently venous Doppler measurements, help choosing the ideal moment for delivering these fragile fetuses. Nevertheless, venous doppler measurements should be combined to other monitoring tools, used longitudinally and only when very preterm birth is expected.

The method for estimating the behavior of the ionospheric irregularity motion vector in the artificially disturbed HF ionospheric region has been proposed, and this behavior has been analyzed based on the simultaneous Doppler observations performed on several paths using the method of bi-static backscatter of diagnostic HF signals by small-scale artificial ionospheric irregularities. The Doppler measurements were performed during the modification of the auroral ionosphere by powerful HF radiowaves emitted by the EISCAT heating facility (Tromso, Norway). It has been obtained that the dynamics of the ionospheric irregularity directions in the F region, calculated based on the Doppler measurements of the total vector of the ionospheric irregularity velocity above the Tromso EISCAT radar at a frequency of 931 MHz, is in satisfactory agreement with such calculations performed using the three-position method.

There has been tremendous progress in observing oscillations in solar-type stars. In a few short years we have moved from ambiguous detections to firm measurements. We briefly review the recent results, most of which have come from high-precision Doppler measurements. We also review briefly the results on giant and supergiant stars and the prospects for the future., Comment: Invited review talk at the "Vienna Workshop on the Future of Asteroseismology", 20-22 September 2006, to appear in Communications in Asteroseismology

The ankle-brachial blood pressure index (ABI) predicts cardiovasular disease. To our knowledge, no study has compared manual ABI measurements with an automated electronic oscillometric method in a population sample. We enrolled 946 residents (50.8% women; mean age, 43.5 years) from 8 villages in JingNing County, Zhejiang Province, P.R. China. We computed ABI as the ratio of ankle-to-arm systolic blood pressures from consecutive auscultatory or Doppler measurements at the posterior tibial and brachial arteries. We also used an automated oscillometric technique with simultaneous ankle and arm measurements (Colin VP-1000). Mean ABI values were significantly higher on Doppler than auscultatory measurements (1.15 vs. 1.07; p

The inter-satellite laser communication of LISA provides three types of measurements, (i) the beatnote between the carrier frequencies of the local laser and the remote laser, called the science measurements or the Doppler measurements, which measures the gravitational wave signal, (ii) the beatnotes of the clock side bands modulated onto the laser, which tries to measure the relative frequency drift of the clocks, (iii) the correlation of the pseudo-random code modulated onto the laser, called the ranging measurements, which intends to measure the absolute distance between the spacecraft. These measurements are described and modelled in details in this chapter. The timing errors and the frequency errors of the clocks are also introduced.

White Rabbit (WR) emerged as an OpenSource and OpenHardware project from CERN, due to stringent timing requirements for data recording in the Large Hadron Collider project. It provides picosecond accuracy timing based on a 1 Gigabit Ethernet (1GE) fibre data network, where all routers are specialised White Rabbit hardware. WR is built over the IEEE Precision Time Protocol (PTP IEEE 1588-2008). The operation of networks of radar sensors requires precision time distribution for collaborative target location, as well as excellent, low phase noise to enable precision Doppler measurements. This paper investigates the potential of the WR for network radar, and compares it to other possible solutions. The radar requirements are defined, followed by WR architectures that could meet these needs. The need of WR for a fibre link is clearly an issue for some applications. A series of experiments in progress are described.

For traditional track initiation algorithms, target tracks are usually initiated using position measurements. However, many radar systems can also provide Doppler measurements. In this paper, we study how to perform track initiation based on position measurements plus Doppler measurements. Due to the fact that target radial velocity usually does not change too much at the track initiation stage, it is reasonable to assume that a target will appear at the same Doppler channel. With this concept, we construct radial range constraint based on Doppler measurement and spatial location constraint based on a maximum velocity, and select validated measurements at the same Doppler channel of a given track head. Numerical results indicate that the proposed algorithm can decrease the false track probability and the average false track number to a large extent. Besides, compared with the traditional sequential track initiation strategy, a better track initiation performance can be obtained at the same false track level.

We describe a new instrument, the Terahertz Limb Sounder (TLS) designed to measure upper atmospheric winds and temperature in the altitude regime between 100 and 150 km. It is based on Doppler measurements of the line of neutral atomic oxygen, OI, at 2.06 THz. This measurement takes advantage of a Schottky diode based all solid state receiver.

Cooperative maneuvers between trains like platooning or dynamic merging and splitting of train sets have the potential to increase efficiency and flexibility in railway operations. However, such maneuvers are safety critical and require continuously accurate relative position and velocity information. This information cannot be provided by infrastructure based train control systems like the European Train Control System, which is limited both in accuracy and update rate. Since the braking distance of trains often exceeds the visible track length, line-of-sight sensors alone are not sufficient for merging and splitting in all situations. We therefore present a Bayesian estimation algorithm that jointly estimates absolute and relative train positions and velocities based on GNSS pseudorange measurements and track map information for increased positioning performance. By transmitting GNSS pseudorange measurements between vehicles, common measurement errors can be eliminated, yielding better relative positioning accuracy. In simulations we show that the proposed algorithm achieves reduced absolute and relative positioning errors compared to algorithms using preprocessed GNSS positions and velocities as measurement input.

during procedures. However none of the studies in the literature have shown the effect of the ureterorenoscopy on renal hemodynamics objectively. In this study we presented our preliminary results of an ongoing study about the renal artery Doppler ultrasonography findings of patients who underwent flexible ureterorenoscopy for kidney stone. METHODS: Patients with kidney stone and designated for retrograde intrarenal surgery (RIRS) with flexible ureterorenoscopy included the study. Renal artery Doppler ultrasonography were done to all patients before anesthesia induction on the operation table and 24 hours later after procedure. Peak systolic velocity (PSV), end diastolic velocity (ESV) and resistive index (RI) measurements were compared statistically. Wilcoxon sum rank test was used to evaluate preand postRIRS renal artery Doppler measurements. RESULTS: A total of 18 patients included the study. Demographic and clinical variables of the patients were presented in Table-1. There were no statistical differences between pre and postRIRS measurements of kidney hemodynamics (Table-2). CONCLUSIONS: RIRS is a minimal invasive treatment method of kidney stone. Our preliminary results showed that renal hemodynamics are not being affected of stone treatment with RIRS procedure.

Background Echocardiography is used on rats but general anesthesia is usually necessary to be able to obtain a good quality echocardiogram. Each type of anesthetic agent has specific impacts on hemodynamics and, therefore, may affect differentially the echocardiographic measurements. Objectives We sought to compare the echocardiograms of normal rats and rats with chronic aortic regurgitation under anesthesia using ketamine-xylazine or isoflurane. Methods Animals underwent an echocardiogram with both drugs sequentially. Echocardiographic measurements were compared. Results Mitral diastolic Doppler measurements (early diastolic filling wave [E] and late atrial diastolic filling wave [A] velocities) were significantly affected by the type of anesthesia in the normal group but not left ventricular dimensions or ejection fraction. Left ventricular dimensions were affected by the type of anesthesia in the aortic regurgitation group and diastolic Doppler flow. Conclusion The anesthetic agent has significant specific impacts on many echocardiographic measurements. Investigators working with rat models should be aware of those potential effects.

We present a method to correct MDI high-resolution Dopplergrams in active regions for systematic observational errors due to the spectral line shape changes. We use a measurement campaign with the Advanced Stokes Polarimeter to investigate the influence of line shape changes in active regions on MDI Dopplergram calibration. An estimate of the width of the Ni I λ6768 absorption line used by MDI to measure velocity provides a linear correction to the standard calibration. This correction can be largely explained by the Zeeman broadening of the absorption line.

This study correlated Doppler resistive indices (RIs) with maximum urethral closure pressures (MUCPs) in women with stress urinary incontinence. We hypothesized that urethral blood flow would be inversely correlated to urethral closure pressures. Fifty-three women underwent spectral Doppler waveform analyses of periurethral vasculature to calculate RI. Urethral morphology including pubovesicular length (PVL) with and without cough was measured. MUCPs were obtained according to International Continence Society guidelines. Physical exam and history were also obtained. Correlation coefficients were calculated for comparisons of Doppler measurements and closure pressures. Fifty patients were required to detect a difference between no correlation and a modest correlation of 0.38 with 80% power and alpha of 0.05. Significance is set at p

Objective Doppler-derived flow velocity measured by transesophageal echocardiography (TEE) may overestimate pulmonary vein stenosis. We hypothesized that combining peak velocity with a stenotic flow pattern improves diagnosis compared with magnetic resonance imaging (MRI). Methods TEE and MRI were performed in 44 patients 19 ± 11 months after radiofrequency catheter ablation. Pulmonary vein stenosis was defined by a peak velocity of 110 cm/s or more plus a stenotic flow pattern (turbulence and reduced flow variation) on TEE and a lumen reduction of more than 50% on MRI. Results In all, 175 pulmonary veins were studied. MRI showed 7 cases of pulmonary vein stenosis that were correctly identified by TEE. In addition, TEE criteria for pulmonary vein stenosis were met in 4 pulmonary veins that did not show obstruction on MRI. In all, 5 pulmonary veins with normal appearance on MRI had peak velocity of 110 cm/s or more with normal flow pattern. Conclusions TEE Doppler measurements can be reliably used to detect or exclude significant pulmonary vein stenosis if the diagnosis is restricted to a combination of elevated peak velocity (≥ 110 cm/s) with turbulence and little flow variation.

We report on the radial-velocity variability of G-type giants based on the results of precise Doppler measurements of 57 stars that were observed for the first 3 years of the Okayama Planet Search Program. This program aims to search for planets around intermediate-mass stars in their evolved stages as late-G giants. We found that most of the targets with B −V 1.0 typically show σ ∼ 20ms−1. In total, about 60% of the targets are stable in radial velocity to a level of σ 30ms−1 are found in 4 stars (HD 41597, HD 134190, HD 161178, and HD 176598). For most of the stars without showing any significant periodicity, we can exclude companions with K > 50ms−1, or m2 sin i > 1.8MJ(a/AU)(M∗/M )1/2 for orbital radii a 1–2AU.

We present here a new result of ground-based asteroseismology obtained with the spectrograph HARPS. The exoplanets host star μ Arae was observed during an 8 nights campaign in order to understand the origin of the overmetallicity of planet-hosting stars. Thanks to very high precision Doppler measurements, we identified more than 20 p -modes in this star and compared it with different models. These results demonstrate the potential of ground-based Doppler asteroseismology and should be considered to be implemented in Dome C in the future in order to benefit of long and uninterrupted observations.

INTRODUCTION Tissue Doppler (TD) imaging is a novel echocardiographic technique that directly measures myocardial velocities. Systolic TD measurements assess left and right ventricular (RV) myocardial contractile function. Diastolic TD values reflect myocardial relaxation, and in combination with conventional Doppler measurements, ratios (E/Ea) have been developed to non-invasively estimate left ventricular (LV) filling pressures. These TD-derived ratios have been helpful in diagnosing elevated LV filling pressures, clinical congestive heart failure (CHF), and the prognosis of patients with cardiac disease and CHF. B-type natriuretic peptide reflects myocardial stretch and has been correlated to LV filling pressures and cardiac morphological abnormalities (depressed EF, RV dysfunction). TD echocardiography is being used in an ever-widening group of patients to assess LV diastolic function, and researchers are actively investigating its correlation and comparison with B-type natriuretic peptide.

A one-dimensional, four state Kalman tracking filter is described for two cases: In case 1, the filter is described for position measurements only and in case 2, the filter is described for both position and Doppler measurements. The filter estimates the range, the range-rate, the rangeacceleration and the range-jerk of a moving target such as an aircraft moving with constant jerk perturbed by a plant noise of zero mean and constant variance which accounts for maneuvers and/or other random factors. In case 1, the range coordinate of the vehicle is assumed to be measured by a track-while-scan radar sensor and incase 2, the rangerate (Doppler) measurements are obtained by a trackwhile-scan radar sensor which employs pulsed Doppler processing such as a moving target detector providing unambiguous Doppler data [1,2]. The measurements are obtained at uniform sampling intervals of time T seconds and all measurements are noisy. The filter structures have been defined and the steady state results are given for both cases.

To analyse the response of Doppler measurements to increased venous return in middle-aged healthy subjects.Left ventricular pulsed Doppler parameters, colour M-mode of early left ventricular filling and septal mitral annulus velocities were measured at baseline and after leg lifting (n=24). Leg lifting resulted in increased stroke volume (69 +/- 14 to 74 +/- 14 ml, P0.01) and peak systolic annulus velocity (6.8 +/- 1.3 to 7.3 +/- 1.1 cm/s, P0.01). Leg lifting enhanced peak early (E) mitral flow (74 +/- 13 to 80 +/- 14 cm/s, P0.01), flow propagation (53 +/- 10 to 59 +/- 13 cm/s, P0.01) and E' diastolic mitral annulus velocity (10.8 +/- 2.2 to 11.7 +/- 2.0 cm/s, P0.01). There was a shortening of E wave deceleration time (178 +/- 27 to 163 +/- 27 ms, P0.01) and isovolumic relaxation time (76 +/- 11 to 68 +/- 10 ms, P0.01). However, individual changes in Doppler parameters differed among subjects.Leg lifting improved myocardial function as manifested by increase in stroke volume, systolic annulus motion and acceleration of relaxation. Flow propagation velocity and diastolic mitral annulus velocities were influenced by the induced change in cardiac preload as well.

Increased arterial stiffness is observed in a number of cases. The analysis of the regional functional arterial properties is of interest to determine the role of a given risk factor on the vascular wall and in some diseases such as atherosclerosis. We analysed the pulse wave velocity (PWV) measured by the Doppler method with 2D guidance and its reproducibility in different arterial segments in 15 men with coronary artery disease. Regional Doppler PWV was defined as the distance between the extremities of a given segment divided by the transit time calculated by Doppler. Intra- and interobserver reproducibilities of the Doppler measurements were studied in all of the subjects. The variation coefficients were low, maximum at the level of ascending aorta and minimal at the level of iliac segment. This good reproducibility was validated by the Bland-Altman method. Moreover, using this Doppler technique, we found a progressive increase in PWV from the ascending aorta to the iliac segment. These data demonstrate that noninvasive Doppler analysis is a feasible and reproducible method to determine regional PWV.

COZMA, D., et al.: Can Simple Doppler Measurements Estimate Interatrial Conduction Time?Prolongation of the interatrial conduction time (ia-CT) is considered an important factor in the pathophysiology of atrial fibrillation (AF) and as a criterion to perform multisite atrial pacing. Measurement of ia-CT requires an electrophysiologic study. The aim of this study was to compare echocardiographic with electrophysiologic measurements to determine if they are correlated. Methods and Results: The study included 32 consecutive patients who underwent electrophysiologic studies. We measured ia-CT between the high right atrium and the distal coronary sinus. In all patients we measured P wave duration, left atrial diameter and area, and ia-CT by Doppler echocardiography was measured as the difference in time intervals between the QRS onset and the tricuspid A wave, and the QRS onset and the mitral A wave (DT). Ia-CT was statistically correlated with DT(r = 0.79, P < 0.0001), but not with P wave duration or left atrial dimensions. Conclusions: Measurement DT may be reliable to estimate ia-CT without invasive procedure. Accordingly, DT could be used as a simple selection criterion when considering patients for atrial resynchronization therapy. (PACE 2003; 26[Pt. II]:436–439)

The use of multiplicative beamforming is described to improve the azimuthal resolution of existing high-frequency surface-wave radar (HFSWR). An existing method by Davies and Ward is used to improve the resolution by a factor of more than two for HFSWR with 16 antennas. The long integration time of HFSWR suppresses the cross products which are the usual drawbacks of this process. The concept is then validated on experimental data with synthetic targets.

A novel architecture of an integrated photonic assisted radar-lidar system based on a single mode-locked laser is proposed and demonstrated. The lidar exploits a multi-frequency optical signal with tunable tones separation allowing a dynamic tradeoff among robustness and sensitivity of measurements. The radar, which employs the mode-locked laser for generating and receiving the radio-frequency signal operates in the X-band and simultaneously with the lidar. Velocity measurements for different tones separation are successfully demonstrated with good agreement between lidar and radar.

Accepted manuscript version. Published version available at https://doi.org/10.1109/TGRS.2015.2439044. © © 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Using data from the Envisat Advanced Synthetic Aperture Radar (ASAR) instrument, this paper demonstrates how the high-precision radial surface velocity product, which will become available with the European Space Agency's Sentinel-1 satellite, can complement the analysis of sea ice motion. High-resolution Doppler frequency measurements are used to estimate the subsecond line-of-sight motion of drifting sea ice in Fram Strait. We compare the method with buoy measurements and a recent cross-correlation algorithm for tracking ice between pairs of images. Maximum speeds measured from the time series were on the order of 20 cm/s. Using our method, we measured instantaneous speeds reaching 40-60 cm/s.

The problem how to detect orbit maneuver in artificial satellites using Doppler measurements, is studied in this paper. To test whether there is such a maneuver on Day 1, we propose an equal-variance test on the post-residuals, for such an event on Day 2 or Day 3, we give another algorithm using predicted residuals. The calculations show that the algorithms can reliably detect any change in the semi-major axis greater than 3 metres when the standard error of the Doppler measurement is 0.2 cm/s.

BACKGROUND: The purpose of this study was to determine the effects of transient arterial blood pressure change on the accuracy of the FloTrac™/Vigileo™ monitor (Edwards Lifesciences, Irvine, CA). METHODS: We compared stroke volume determined with the FloTrac/Vigileo with Doppler during anesthetic induction in 20 patients undergoing abdominal aortic reconstruction. RESULTS: The difference between the FloTrac measurements of stroke volume and the Doppler measurements of stroke volume was -7.5 ± 20.5 mL (mean ± SD) before induction, 0.3 ± 14.9 before laryngoscopy, 17.5 ± 26.9 during laryngoscopy, 20.5 ± 27.6, and -4.5 ± 16.4 mL 3 minutes after endotracheal tube placement. CONCLUSION: The FloTrac/Vigileo measured stroke volume with reasonable accuracy during transient hypotension but overestimated stroke volume during transient hypertension.

International audience; We propose an approach for future localization systems which is quite different from the Global Navigation Satellite Systems standard. The idea is to think about the localization process in a relative way, i.e. to consider the entities with regard to each other. We aim at designing a relative system in order to simplify the practical aspects (low power because low range, no complex synchronization processes, etc.), but also in order to considerably improve the precision (by using local phase measurements of carriers typically). The main idea is based on the fact that it is often sufficient to have a "local understanding" of the localization and that the knowledge of the "geometry" of the distribution of a set of entities allows us to perform the mission. Furthermore, we know that it is possible to achieve accurate relative measurements between two entities, by using measurements of phases of a carrier for example. We shall thoroughly describe the problem of what could be a precise positioning system not requiring any specific infrastructure, and affordable in terms of technologies as well as low energy consumption. This is made possible by use of mature technologies and by the fact that the proposed radio communication links are carried out at short distances, only between two entities. We suggest using only Doppler-like measurements, similar to a radar approach, but through a single way transmission. It is then possible to know the value of the projection of the difference of the speed vectors of the two entities on the axis which separates them. By using only these measurements, we define a new type of positioning and we also analyze the possibility to go back to an absolute positioning, sometimes made possible by the availability of absolute data, as distances or geographical coordinates of a few terminals. In a second approach, we deal with geometry (the calculation of angles) while introducing measurements relative to a reference terminal. Having studied the feasibility to calculate the various angles, from only Doppler-like measurements of four terminals relatively with the others, we show it is possible to obtain the relative positions of the entities. The problem is however not trivial because numerous symmetries exist. Simulations allow us to provide first validations of these concepts. A third approach, still based on relative measurements between two terminals, consists in using distance measurements. We could envisage for example time of flight measurements between two Ultra Wide Band (UWB) knots. In such a case, the calculations are much easier

New techniques of Tissue Doppler Imaging (TDI) enable the measurement of myocardial velocities and provide information about left ventricular (LV) diastolic function. Recent studies explored the prognostic role of TDI-derived indexes. However, these studies considered only total mortality and did not provide information on cardiovascular mortality and morbidity. Therefore, we investigated in continuous and categorical analyses whether Doppler diastolic indexes contained any prognostic information over and beyond traditional cardiovascular risk factors in a general population.We measured early and late diastolic peak velocities of mitral inflow (E and A) by conventional Doppler, and the mitral annular velocities (e' and a') by TDI in 793 participants (mean age 50.9 years). We calculated multivariable-adjusted hazard ratios for conventional and TDI Doppler indexes, while accounting for family cluster and cardiovascular risk factors. Median follow-up was 4.8 years (5th to 95th percentile, 3.0 to 5.4). With adjustments applied for covariables, e' velocity was a significant predictor of fatal and nonfatal cardiovascular (n=59; P=0.004) and cardiac events (n=40; P=0.001). TDI e' yielded a net reclassification improvement of 54.2% for cardiovascular and 64.0% for cardiac events. Hazard ratios of all cardiovascular (2.21; P=0.042) and cardiac (4.50; P=0.002) events were significantly elevated in participants with increased LV filling pressure compared with subjects with normal diastolic function.TDI e' velocity is a significant predictor of fatal and nonfatal cardiovascular events in a general population. Furthermore, we observed an increase in all cardiovascular events in the diastolic dysfunction group characterized by elevated LV filling pressure.

Precise Doppler measurements during 4.4 yr from the Keck/HIRES spectrometer reveal two superimposed Keplerian velocity variations for HD 168443 (G6 IV). A simultaneous orbital fit to both companions yields companion masses of M sin i = 7.7 and 17.2 MJUP, orbital periods of P = 58 days and 4.8 yr, semimajor axes of a = 0.29 and 2.9 AU, and eccentricities of e = 0.53 and 0.20. An upper limit to the mass of the outer companion of 42 MJUP is derived from the lack of astrometric wobble. The outer companion was not detected with Keck adaptive optics in the near-IR. Dynamical simulations show that the system is remarkably stable for all possible masses of both companions. The two orbiting companions have masses that are probably near and slightly above the upper end of the observed mass distribution of "planets" at 10 MJUP. Formation in a protoplanetary disk seems plausible. But these objects present a puzzle about their formation and dynamical history, as well as about their possible kinship with planetary systems and triple-star systems.

The five lowest rotational transitions of 12C180 (J =2 ← 1 to J = 6 ← 5) have been measured by saturation dip spectroscopy with an experimental accuracy of 1 to 1.5 kHz, employing phase-stabilized backward-wave oscillators. The five J rotational transitions cover the frequency range between 219 and 658 GHz. In addition, we have measured in the Doppler limited mode the rotational transitions J = 1 ← 0, J = 7 ← 6 and J = 8 ← 7. The accuracy achieved for the individual frequencies ranges between 5 and 20 kHz. Moreover the three rotational transitions J = 16 ← 15 to J = 18 ← 17 in the frequency region 1.7-2.0 THz were measured with an accuracy of 15 to 30 kHz by using the Cologne side­ band spectrometer for terahertz applications COSSTA.

PURPOSE The objective of this study was to evaluate blood flow changes inside normally functioning transjugular intrahepatic portosystemic shunts (TIPS), using Colour Doppler ultrasound (CDUS) and pulsed Doppler ultrasound (PDUS). MATERIAL AND METHODS In a prospective study 72 patients (mean age 54, range 36-78 years) underwent TIPS placement, portal angiography, CDUS and PDUS examinations. Along the TIPS Doppler measurements were taken at the portal in the central part and at the venous end of the TIPS. RESULTS In well functioning TIPS the mean peak velocity (PV) on the portal side was 39 cm/s (range 22-72 cm/s), in the area of the incoming right portal end, branch 62 cm/s (range 40-109 cm/s) and at the site of the incoming hepatic vein 139 cm/s (range 88-220 cm/s). In the punctured portal and hepatic vein the mean PV was 25 cm/s (range 15-30 cm/s) and 18 cm/s (15-22 cm/s) respectively. CONCLUSION A velocity gradient between the portal and the venous side of the TIPS is a normal finding, caused by the branches of the portal and hepatic vein, joining the TIPS from the side and is characteristic of a normally functioning TIPS.

A recently developed noncoherent Doppler tracking technique has been experimentally verified at the NASA Deep Space Network (DSN) Test Facility. This technique permits highly accurate two-way Doppler measurements to he made with a simple transceiver system. The accuracy goal of 0.1 mm/s has been verified as well as the compatibility of the technique with the equipment, practices, and the radiometric file formats used by the DSN. The test setup and measured system performance are described. Several test conditions were varied including signal level, transceiver oscillator frequency drift, physical movement, and telemetry bit rate. A side-by-side comparison of the performance with a coherent transponder was also obtained.

The common hepatic artery in 10 healthy adult beagles, 20 healthy pups (13 Deerhounds and seven Irish Wolfhounds), and seven dogs with either a congenital or acquired hepatic disorder was examined by duplex-Doppler ultrasonography. Peak systolic velocity (Vs), resistive index (RI), pulse rate, angle of insonation, and sample volume depth were recorded. Measurements in Beagles were made after a 24 h fast and repeated 2 h after feeding. The mean Vs and RI in fasted Beagles were 1.5 m/s (range 1.1-2.3 m/s) and 0.68 (range 0.62-0.74), respectively. Postprandially, there were no significant differences in any of these variables. Mean Vs and RI were lower in pups: 1.0 m/s (range 0.8-1.3 m/s) and 0.59 (range 0.46-0.65), respectively (P < .001). Two dogs with congenital arterioportal fistula had higher mean Vs (P < .001) and lower mean RI (P < .05) than normal pups. No significant differences were detected between normal Beagles, three dogs with portal vein thrombosis, and two dogs with acquired hepatic insufficiency. Differences in measured hepatic blood flow in dogs of different age or breed will complicate diagnostic use of hepatic arterial Doppler measurements.

Doppler measurements from the Keck/HIRES spectrometer of the G3 V star HD 187123 reveal Keplerian variations with a period of 3.097 days and a semiamplitude of 72 m s–1. An orbital fit yields a companion mass of M = 0.52 MJUP/ sin i}, a semimajor axis of a = 0.042 AU, and an eccentricity of e = 0.03 (consistent with zero). HD 187123 appears similar to the Sun in mass, age, chromosphere, and rotation rate. Although unlikely, non-Keplerian explanations for the Doppler variations, such as spots and pulsation, cannot be ruled out and require future photometry and spectroscopy.

Background —Myocardial fractional flow reserve (FFR) is based on pressure measurements. We have now sought to establish a Doppler-based concept of relative flow velocity reserve (RFVR) for the functional assessment of stenosis severity in epicardial coronary arteries. A clear threshold value to discriminate the functional severity of a coronary stenosis does not exist for coronary flow velocity reserve (CVR) based on intracoronary Doppler measurements. In contrast, the concept of FFR, which is based on intracoronary pressure measurements, has been extensively validated. An FFR value below 0.75 reliably indicates a significant stenosis. Methods and Results —RFVR is calculated as the ratio between distal CVR in the stenosed target vessel and distal CVR in a nonstenotic reference vessel. In 21 patients, RFVR was determined in 24 target vessels by use of intracoronary adenosine and correlated to the FFR, determined as the ratio of mean poststenotic to aortic pressures, in the target vessel. Stenosis severity was classified according to quantitative coronary angiography analysis. Reference diameter was 3.0±0.4 mm (mean±SD), and area stenosis was 74±15% (range, 40% to 95%). CVRs in the target and reference vessels were 2.1±0.5 and 2.6±0.7, respectively. FFR ranged from 0.49 to 0.99 (mean, 0.81±0.15) and RFVR from 0.53 to 1.0 (mean, 0.82±0.13). Poststenotic CVR did not correlate with either percent area stenosis ( r =0.27, P =NS) or FFR ( r =0.33, P =NS). In contrast, FFR as well as RFVR showed a curvilinear relation to percent area stenosis ( r =0.89, P r =0.79, P r =0.91, P Conclusions —RFVR correlates closely to FFR and to percent area stenosis, whereas the correlation of CVR with FFR and percent area stenosis is rather poor. RFVR is a promising new concept for assessment of coronary stenosis severity and clinical decision making based on Doppler measurements.

We describe an approach for a medium accuracy position determination of a user terminal (UT) on the Earth surface, using one or two low Earth orbit (LEO) satellites. The positioning approach is intended to meet the requirements of a worldwide personal communications system using LEO satellites. The basic two requirements are: (1) immediate positioning, and (2) horizontal position accuracy of the order of 10 km. Those requirements stem from the need of the system to know the user's approximate location before it connects his call. The approach makes use of the two-way communication with the UT, which can receive, transmit, and make its own measurements. Delay and Doppler measurements are used in order to enable instantaneous positioning with one satellite, and in order to achieve unambiguous positioning with two satellites. A simplified Globalstar satellite constellation and the expected Globalstar delay and frequency measurement accuracy are used to demonstrate the concept and to evaluate its performances.

We collected data for flight speeds of foraging common nighthawks (Chordeiles minor) flying under natural conditions using a Doppler radar and compared them with data collected by timing flights over a known distance for the same species. We also compared our Doppler radar measures of flight speed with the values of minimum power speed (Vmp) and maximum range speed (Vmr) predicted from aerodynamic models. Our measurements showed that under natural conditions, nighthawks flew at 6.5 ± 1.1 m-s−1, significantly faster than the 5.3 ± 1.2 m-s−1 derived by timing flights over measured distances. Doppler measurements indicate that on average, nighthawks flew significantly faster than the predicted Vmp, but slower than the predicted Vmr although there was considerable variation. Our results confirm that the method of measuring flight speeds can be important and suggest that the mechanics of hunting insects and not energetics, may be most important in determining the flight speed used by foraging common n...

The great increase in the accuracy of Doppler measurements in space requires a rigorous definition of the observed quantity in a moving medium, such as the solar wind. This is usually done in two different ways: in the phase point of view it is the time derivative of the correction to the optical path; in the ray point of view—suitable when the medium is confined to a small part of the ray—the signal is obtained from the deflection produced in the ray. They can be reconciled by using the time derivative of the optical path in the Lagrangean sense, i.e., differentiating from ray to ray. A rigorous derivation of this result requires an understanding, through relativistic Hamiltonian theory, of the delicate interplay between rays and phase; this is accomplished with the help of a general perturbation theorem which generalizes the concept of the Doppler effect as a Lagrangean derivative. Relativistic corrections O(v) due to retardation are obtained, well within the expected sensitivity of Doppler experiments near solar conjunction.

The increase in the accuracy of Doppler measurements in space requires a rigorous definition of the observed quantity when the propagation occurs in a moving, and possibly dispersive medium, like the solar wind. This is usually done in two divergent ways: in the phase viewpoint it is the time derivative of the correction to the optical path; in the ray viewpoint the signal is obtained form the deflection produced in the ray. They can be reconciled by using the time derivative of the optical path in the Lagrangian sense, i.e. differentiating from ray to ray. To rigorously derive this result an understanding, through relativistic Hamiltonian theory, of the delicate interplay between rays and phase is required; a general perturbation theorem which generalizes the concept of the Doppler effect as a Lagrangian derivative is proved. Relativistic retardation corrections O(v) are obtained, well within the expected sensitivity of Doppler experiments near solar conjunction.