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Sample records for blood vector velocity

  1. Examples of in-vivo blood vector velocity estimation

    DEFF Research Database (Denmark)

    Udesen, Jesper; Nielsen, Michael Bachmann; Nielsen, Kristian R.

    2007-01-01

    In this paper examples of in-vivo blood vector velocity images of the carotid artery are presented. The transverse oscillation (TO) method for blood vector velocity estimation has been used to estimate the vector velocities and the method is first evaluated in a circulating flowrig where...

  2. Vector blood velocity estimation in medical ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Gran, Fredrik; Udesen, Jesper

    2006-01-01

    Two methods for making vector velocity estimation in medical ultrasound are presented. All of the techniques can find both the axial and transverse velocity in the image and can be used for displaying both the correct velocity magnitude and direction. The first method uses a transverse oscillation...... in the ultrasound field to find the transverse velocity. In-vivo examples from the carotid artery are shown, where complex turbulent flow is found in certain parts of the cardiac cycle. The second approach uses directional beam forming along the flow direction to estimate the velocity magnitude. Using a correlation...

  3. Recent advances in blood flow vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav; Udesen, Jesper;

    2011-01-01

    investigated using both simulations, flow rig measurements, and in-vivo validation against MR scans. The TO method obtains a relative accuracy of 10% for a fully transverse flow in both simulations and flow rig experiments. In-vivo studies performed on 11 healthy volunteers comparing the TO method...... been acquired using a commercial implementation of the method (BK Medical ProFocus Ultraview scanner). A range of other methods are also presented. This includes synthetic aperture imaging using either spherical or plane waves with velocity estimation performed with directional beamforming or speckle...... Medical 8804 transducer. This resulted in a relative standard deviation of 1.2% for a fully transverse flow. Plane wave imaging was also implemented on the RASMUS scanner and a 100 Hz frame rate was attained. Several vector velocity image sequences of complex flow were acquired, which demonstrates...

  4. Improved accuracy in the estimation of blood velocity vectors using matched filtering

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Gori, P.

    2000-01-01

    that the complete velocity vector can be found, if the received signals are focused along lines parallel to the direction of the blood flow. A fairly broad beam is emitted in the approach, and this gives rise to a widening in the profiles of the estimated velocity. To reduce this effect, a focused ultrasound......The blood velocity can be estimated by finding the shift in position of the blood scatterers between subsequent ultrasonic pulse emissions through cross-correlation of the received RF signals. Usually only the velocity component along the beam direction is found. It was shown in a previous paper...

  5. Blood vector velocity estimation using an autocorrelation approach: In vivo Investigation

    DEFF Research Database (Denmark)

    Udesen, Jesper; Bachmann, Michael; Rue, Kristina

    2005-01-01

    In conventional techniques for blood velocity estimation, only the axial component of the velocity vector is found. We have previously shown that it is possible to estimate the 2-D blood velocity vector both in simulations and in flow phantom experiments using a fast and inexpensive method (the...... deg phase shift in the lateral direction. The TO method works at angles where conventional methods fails to estimate any blood movement, i.e. when the angle between the ultrasound beam and the velocity vector is approximately 90 deg. In this paper the first in-vivo color flow map (CFM) images...... are presented using the TO method. A 128 element 5 MHz linear array transducer was used together with the experimental ultrasound scanner RASMUS operating at a sampling frequency of 40 MHz with a pulse repetition frequency of 24 kHz. After sampling the received channel data were beamformed off...

  6. Fast Blood Vector Velocity Imaging: Simulations and Preliminary In Vivo Results

    DEFF Research Database (Denmark)

    Udesen, Jesper; Gran, Fredrik; Hansen, Kristoffer Lindskov;

    2007-01-01

    I Background: Conventional ultrasound methods for acquiring color flow images of the blood velocity are limited by a relatively low frame rate and are restricted to only give velocity estimates along the ultrasound beam direction. To circumvent these limitations, we propose a method where the frame...... rate can be significantly increased, and the full 2-D vector velocity of the blood can be estimated. II Method: The method presented in this paper uses three techniques: 1) The ultrasound is not focused during the transmit of the ultrasound signals, and a full speckle image of the blood can be acquired...... for each pulse emission. 2) The transmitted pulse consists of a 13 bit Barker code which is transmitted simultaneously from each transducer element. 3) The 2-D vector velocity of the blood is found using 2-D speckle tracking between segments in consecutive speckle images. III Results: The method was tested...

  7. High frame-rate blood vector velocity imaging using plane waves: simulations and preliminary experiments

    DEFF Research Database (Denmark)

    Udesen, J.; Gran, F.; Hansen, K.L.

    2008-01-01

    Conventional ultrasound methods for acquiring color images of blood velocity are limited by a relatively low frame-rate and are restricted to give velocity estimates along the ultrasound beam direction only. To circumvent these limitations, the method presented in this paper uses 3 techniques: 1...... carotid artery of a healthy male was scanned with a scan sequence that satisfies the limits set by the Food and Drug Administration. Vector velocity images were obtained with a frame-rate of 100 Hz where 40 speckle images are used for each vector velocity image. It was found that the blood flow...... approximately followed the vessel wall, and that maximum velocity was approximately 1 m/s, which is a normal value for a healthy person. To further evaluate the method, the test person was scanned with magnetic resonance (MR) angiography. The volume flow derived from the MR scanning was compared with that from...

  8. Fast Blood Vector Velocity Imaging using ultrasound: In-vivo examples of complex blood flow in the vascular system

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Gran, Fredrik;

    2008-01-01

    speckle tracking between segments in consecutive speckle images. The flow patterns of six bifurcations and two veins were investigated in-vivo. It was shown: 1) that a stable vortex in the carotid bulb was present opposed to other examined bifurcations, 2) that retrograde flow was present......Conventional ultrasound methods for acquiring color flow images of the blood motion are restricted by a relatively low frame rate and angle dependent velocity estimates. The Plane Wave Excitation (PWE) method has been proposed to solve these limitations. The frame rate can be increased, and the 2-D...... vector velocity of the blood motion can be estimated. The transmitted pulse is not focused, and a full speckle image of the blood can be acquired for each emission. A 13 bit Barker code is transmitted simultaneously from each transducer element. The 2-D vector velocity of the blood is found using 2-D...

  9. High Frame-Rate Blood Vector Velocity Imaging Using Plane Waves: Simulations and Preliminary Experiments

    DEFF Research Database (Denmark)

    Udesen, Jesper; Gran, Fredrik; Hansen, Kristoffer Lindskov;

    2008-01-01

    Conventional ultrasound methods for acquiring color images of blood velocity are limited by a relatively low frame-rate and are restricted to give velocity estimates along the ultrasound beam direction only. To circumvent these limitations, the method presented in this paper uses 3 techniques: 1......) The ultrasound is not focused during the transmissions of the ultrasound signals; 2) A 13-bit Barker code is transmitted simultaneously from each transducer element; and 3) The 2-D vector velocity of the blood is estimated using 2-D cross-correlation. A parameter study was performed using the Field II program......, and performance of the method was investigated when a virtual blood vessel was scanned by a linear array transducer. An improved parameter set for the method was identified from the parameter study, and a flow rig measurement was performed using the same improved setup as in the simulations. Finally, the common...

  10. 2-D blood vector velocity estimation using a phase shift estimator

    DEFF Research Database (Denmark)

    Udesen, Jesper

    2006-01-01

    In this PhD thesis a method for 2-D blood velocity estimation called \\textit{the transverse oscillation method} (TO) is investigated. The thesis is divided into two parts. In the first part the basic principles in conventional 1-D flow estimation are described, and the state of the art for 2-D...... velocity estimation is discussed. The TO method is introduced, and the basic theory behind the method is explained. This includes the creation of the acoustic fields, beamforming, echo-canceling and the velocity estimator. In the second part of the thesis the eight papers produced during this PhD project...... when the angle between the blood and the ultrasound beam is above $50^\\circ$. Furthermore, the TO method is tested in-vivo where the scannings are performed by skilled sonographers. The in-vivo scannings resulted in a sequence of 2-D vector CFM images which showed 2-D flow patterns in the bifurcation...

  11. Estimation of blood velocity vectors using transverse ultrasound beam focusing and cross-correlation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Lacasa, Isabel Rodriguez

    1999-01-01

    Modern ultrasound scanners estimate the blood velocity by tracking the movement of the blood scatterers along the ultrasound beam. This is done by emitting pulsed ultrasound fields and finding the shift in position from pulse to pulse by correlating the received signals. Only the velocity component...... along the beam direction is found, and this is a serious limitation in the current scanners, since most blood vessels are parallel to the skin surface. A method to find the velocity across the vessel has been suggested by Bonnefous (1988). Here a number of parallel receive beams are measured and used...... or across it or in any direction to the beam. The focused lines, thus, follow the flow and a cross-correlation of lines from different pulses can find the movement of the blood particles between pulse emissions and, thus, the blood velocity. The new approach is investigated using the Field II simulation...

  12. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  13. Demonstration of a Vector Velocity Technique

    DEFF Research Database (Denmark)

    Hansen, Peter Møller; Pedersen, Mads M.; Hansen, Kristoffer L.;

    2011-01-01

    With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60–70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa...

  14. Examples of Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Hansen, Peter M.; Pedersen, Mads M.; Hansen, Kristoffer L.

    2011-01-01

    To measure blood flow velocity in vessels with conventional ultrasound, the velocity is estimated along the direction of the emitted ultrasound wave. It is therefore impossible to obtain accurate information on blood flow velocity and direction, when the angle between blood flow and ultrasound wa...... with a 90° angle on the vessel. Moreover secondary flow in the abdominal aorta is illustrated by scanning on the transversal axis....

  15. Phase-resolved functional optical coherence tomography: simultaneous imaging of in situ tissue structure, blood flow velocity, standard deviation, birefringence, and Stokes vectors in human skin

    Science.gov (United States)

    Ren, Hongwu; Ding, Zhihua; Zhao, Yonghua; Miao, Jianjun; Nelson, J. Stuart; Chen, Zhongping

    2002-10-01

    We describe a phase-resolved functional optical coherence tomography system that can simultaneously yield in situ images of tissue structure, blood flow velocity, standard deviation, birefringence, and the Stokes vectors in human skin. Multifunctional images were obtained by processing of analytical interference fringe signals derived from two perpendicular polarization-detection channels. The blood flow velocity and standard deviation images were obtained by comparison of the phases from pairs of analytical signals in neighboring A-lines in the same polarization state. The analytical signals from two polarization-diversity detection channels were used to determine the four Stokes vectors for four reference polarization states. From the four Stokes vectors, the birefringence image, which is not sensitive to the orientation of the optical axis in the sample, was obtained. Multifunctional in situ images of a port wine stain birthmark in human skin are presented.

  16. Preliminary evaluation of vector flow and spectral velocity estimation

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per

    Spectral estimation is considered as the golden standard in ultrasound velocity estimation. For spectral velocity estimation the blood flow angle is set by the ultrasound operator. Vector flow provides temporal and spatial estimates of the blood flow angle and velocity. A comparison of vector flow...... agrees with the spectral flow angle. The vector velocity estimates agrees with the spectral estimates at PS and ED. From preliminary data it is concluded that vector flow angle estimation can replace the operator-dependent angle correction used for spectral velocity estimation....... estimation and spectral estimates is presented. The variation of the blood flow angle and the effect on the velocity estimate is investigated. The right common carotid arteries of three healthy volunteers were scanned. Real-time spectral and vector flow data were obtained simultaneously from one range gate...

  17. Application of Vectors to Relative Velocity

    Science.gov (United States)

    Tin-Lam, Toh

    2004-01-01

    The topic 'relative velocity' has recently been introduced into the Cambridge Ordinary Level Additional Mathematics syllabus under the application of Vectors. In this note, the results of relative velocity and the 'reduction to rest' technique of teaching relative velocity are derived mathematically from vector algebra, in the hope of providing…

  18. Validation of Transverse Oscillation Vector Velocity Estimation In-Vivo

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Thomsen, Carsten

    2007-01-01

    method Transverse Oscillation (TO), which combines estimates of the axial and the transverse velocity components in the scan plane, makes it possible to estimate the vector velocity of the blood regardless of the Doppler angle. The present study evaluates the TO method with magnetic resonance angiography...

  19. New technology - demonstration of a vector velocity technique

    DEFF Research Database (Denmark)

    Møller Hansen, Peter; Pedersen, Mads M; Hansen, Kristoffer L;

    2011-01-01

    With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60-70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa...

  20. Introduction to vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Udesen, Jesper; Hansen, Kristoffer Lindskov;

    Current ultrasound scanners can only estimate the velocity along the ultrasound beam and this gives rise to the cos() factor on all velocity estimates. This is a major limitation as most vessels are close to perpendicular to the beam. Also the angle varies as a function of space and time making...

  1. Phased-array vector velocity estimation using transverse oscillations

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Marcher, Jønne; Jensen, Jørgen Arendt

    2012-01-01

    A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical applicabil......A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical...

  2. In Vivo 3-D Vector Velocity Estimation with Continuous Data

    DEFF Research Database (Denmark)

    Holbek, Simon; Pihl, Michael Johannes; Ewertsen, Caroline

    2015-01-01

    In this study, a method for estimating 3-D vector velocities at very high frame rate using continuous data acquisition is presented. An emission sequence was designed to acquire real-time continuous data in one plane. The transverse oscillation (TO) method was used to estimate 3-D vector flow...... measurements, three heart cycles acquired at 2.1 kHz showed peak out-of-plane velocities of 83 cm/s, 87 cm/s and 90 cm/s in agreement with the 92 cm/s found with spectral Doppler. Mean flow rate was estimated to 257 ml/min. The results demonstrate that accurate real-time 3- D vector velocities can be obtained...... using the TO method, which can be used to improve operator-independece when examining blood flow in vivo, thereby increasing accuracy and consistency....

  3. An improved estimation and focusing scheme for vector velocity estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Munk, Peter

    1999-01-01

    beamforming method. A modified autocorrelation approach employing fourth order moments of the input data is used for velocity estimation. The new estimator calculates the axial and lateral velocity component independently of each other. The estimation is optimized for differences in axial and lateral......The full blood velocity vector must be estimated in medical ultrasound to give a correct depiction of the blood flow. This can be done by introducing a transversely oscillating pulse-echo ultrasound field, which makes the received signal influenced by a transverse motion. Such an approach...... modulation periods in the ultrasound field by using a lag different from one in the estimation process, and noise artifacts are reduced by using averaging of RF samples. Furthermore, compensation for the axial velocity can be introduced, and the velocity estimation is done at a fixed depth in tissue...

  4. Vector Velocity Imaging Using Cross-Correlation and Virtual Sources

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund; Kortbek, Jacob; Jensen, Jørgen Arendt

    2006-01-01

    Previous investigations have shown promising results in using the directional cross-correlation method to estimate velocity vectors. The velocity vector estimate provides information on both velocity direction and magnitude. The direction is estimated by beamforming signals along directions...

  5. In vivo comparison of three ultrasound vector velocity techniques to MR phase contrast angiography

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Oddershede, Niels;

    2009-01-01

    The objective of this paper is to validate angle independent vector velocity methods for blood velocity estimation. Conventional Doppler ultrasound (US) only estimates the blood velocity along the US beam direction where the estimate is angle corrected assuming laminar flow parallel to vessel...... boundaries. This results in incorrect blood velocity estimates, when angle of insonation approaches 90° or when blood flow is non-laminar. Three angle independent vector velocity methods are evaluated in this paper: directional beamforming (DB), synthetic aperture flow imaging (STA) and transverse...... can give the clinician a novel tool for cardiovascular disease assessment....

  6. Performance of a vector velocity estimator

    DEFF Research Database (Denmark)

    Munk, Peter; Jensen, Jørgen Arendt

    1998-01-01

    It is a well-known limitation of all commercially available scanners that only the velocity component along the propagation direction of the emitted pulse is measured, when evaluating blood velocities with ultrasound. Proposals for solving this limitation using several transducers or speckle trac...... processing preceding the beamforming can be implemented using standard signal processors, and it is robust since the autocorrelation method is used...

  7. Velocity envelope of vector flow estimation with spatial quadrature

    Science.gov (United States)

    Kerr, Richard F.; Anderson, Martin E.

    2003-05-01

    We present the results of two studies investigating the optimal aperture configuration for maximized lateral blood flow velocity estimation using Heterodyned Spatial Quadrature. Our objective was to determine the maximum velocities that can be estimated at Doppler angles of 90 degrees and 60 degrees with a bias of less than 5% for both uniform scatterer motion in a tissue-mimicking phantom and blood-mimicking fluid circulated through a wall-less vessel flow phantom. Constant flow rates ranging from 3.0 to 18.0 ml/sec were applied in the flow phantom, producing expected peak velocities of 15.0 to 89.8 cm/sec under laminar flow conditions. Velocity estimates were obtained at each flow rate using 256 trials, with each trial consisting of an ensemble of 32 vectors. For an f/1 receive geometry with bi-lobed Hamming apodization, all peak flow velocities tested were estimated to within 5% of their expected values for both 90 degree and 60 degree Doppler angles. An f/2 receive geometry featuring bi-lobed Blackman apodization generally provided accurate lateral velocity estimates up to 71.9 cm/sec for a Doppler angle of 90 degrees, and accurate lateral component estimates up to 50.1 cm/sec for a 60 degree Doppler angle. The implications of these findings will be discussed.

  8. Middle cerebral artery blood velocity during running

    DEFF Research Database (Denmark)

    Lyngeraa, Tobias; Pedersen, Lars Møller; Mantoni, T;

    2013-01-01

    Running induces characteristic fluctuations in blood pressure (BP) of unknown consequence for organ blood flow. We hypothesized that running-induced BP oscillations are transferred to the cerebral vasculature. In 15 healthy volunteers, transcranial Doppler-determined middle cerebral artery (MCA....... During running, rhythmic oscillations in arterial BP induced by interference between HR and step frequency impact on cerebral blood velocity. For the exercise as a whole, average MCA velocity becomes elevated. These results suggest that running not only induces an increase in regional cerebral blood flow...

  9. A new estimator for vector velocity estimation [medical ultrasonics

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2001-01-01

    A new estimator for determining the two-dimensional velocity vector using a pulsed ultrasound field is derived. The estimator uses a transversely modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation...... be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce the influence of a spatial velocity spread. Examples for different velocity vectors and field conditions are shown using both simple and more complex field simulations. A relative accuracy of 10.1% is obtained...... for the transverse velocity estimates for a parabolic velocity profile for flow transverse to the ultrasound beam and a SNR of 20 dB using 20 pulse-echo lines. The overall bias in the estimates was -4.3%....

  10. Algorithms for estimating blood velocities using ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2000-01-01

    Ultrasound has been used intensively for the last 15 years for studying the hemodynamics of the human body. Systems for determining both the velocity distribution at one point of interest (spectral systems) and for displaying a map of velocity in real time have been constructed. A number of schemes...... have been developed for performing the estimation, and the various approaches are described. The current systems only display the velocity along the ultrasound beam direction and a velocity transverse to the beam is not detected. This is a major problem in these systems, since most blood vessels...

  11. Ultrasound systems for blood velocity estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1998-01-01

    Medical ultrasound scanners can be used both for displayinggray-scale images of the anatomy and for visualizing theblood flow dynamically in the body.The systems can interrogate the flow at a single position in the bodyand there find the velocity distribution over time. They can also show adynamic...... color image of velocity at up to 20 to 60 frames a second. Both measurements are performedby repeatedly pulsing in the same direction and then usethe correlation from pulse to pulse to determine the velocity.The paper gives a simple model for the interactionbetween the ultrasound and the moving blood...

  12. Adaptive blood velocity estimation in medical ultrasound

    DEFF Research Database (Denmark)

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

    2007-01-01

    This paper investigates the use of data-adaptive spectral estimation techniques for blood velocity estimation in medical ultrasound. Current commercial systems are based on the averaged periodogram, which requires a large observation window to give sufficient spectral resolution. Herein, we propose...

  13. Estimation of blood velocities using ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    Ultrasound systems are especially useful in estimating blood velocities in the human body because they are noninvasive and can display an estimate in real time. This book offers a comprehensive treatment of this relatively new, important technology. The book begins with an introduction to ultraso......Ultrasound systems are especially useful in estimating blood velocities in the human body because they are noninvasive and can display an estimate in real time. This book offers a comprehensive treatment of this relatively new, important technology. The book begins with an introduction...... to ultrasound, flow physics, and the circulatory system. Next, the interaction of ultrasound with blood is discussed. The special contribution of the book lies in the remaining chapters, which offer a lucid, thorough description of continuous and pulsed wave systems, the latest systems for doing color flow...

  14. In-vivo studies of new vector velocity and adaptive spectral estimators in medical ultrasound

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov

    observation window compared to the conventional spectral Doppler method. The thesis shows, that novel information can be obtained with vector velocity methods providing quantitative estimates of blood flow and insight in to the complexity of fluid dynamics. This could give the clinician a new tool......In this PhD project new ultrasound techniques for blood flow measurements have been investigated in-vivo. The focus has mainly been on vector velocity techniques and four different approaches have been examined: Transverse Oscillation, Synthetic Transmit Aperture, Directional Beamforming and Plane...... Wave Excitation. Furthermore two different adaptive spectral estimators have been investigated: Blood spectral Power Capon method (BPC) and Blood Amplitude and Phase Estimation method (BAPES). The novel techniques investigated in this thesis are developed to circumvent some of the main limitations...

  15. Real-Time GPU Implementation of Transverse Oscillation Vector Velocity Flow Imaging

    DEFF Research Database (Denmark)

    Bradway, David; Pihl, Michael Johannes; Krebs, Andreas

    2014-01-01

    , Open Computing Language (OpenCL) is used to estimate 2-D vector velocity flow in vivo in the carotid artery. Data are streamed live from a BK Medical 2202 Pro Focus UltraView Scanner to a workstation running a research interface software platform. Processing data from a 50 millisecond frame of a duplex......Rapid estimation of blood velocity and visualization of complex flow patterns are important for clinical use of diagnostic ultrasound. This paper presents real-time processing for two-dimensional (2-D) vector flow imaging which utilizes an off-the-shelf graphics processing unit (GPU). In this work...

  16. Counterposed phase velocity and energy-transport velocity vectors in a dielectric-magnetic uniaxial medium

    OpenAIRE

    Lakhtakia, A.; McCall, M. W.

    2004-01-01

    When a plane wave is launched from a plane surface in a linear, homogenous, dielectric-magnetic, uniaxial medium, we show that its phase velocity and the energy-transport velocity vectors can be counterposed (i.e., lie on different sides of the surface normal) under certain circumstances.

  17. In-vivo Examples of Flow Patterns With The Fast Vector Velocity Ultrasound Method

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Gran, Fredrik

    2009-01-01

    Purpose: Conventional ultrasound methods for acquiring color flow images of the blood motion are limited by a relatively low frame rate and are restricted to only giving velocity estimates along the ultrasound beam direction. To circumvent these limitations, the Plane Wave Excitation (PWE) method...... a fast vector velocity ultrasound method, in-vivo scans have been recorded where complex flow patterns were visualized in greater detail than previously visualized by conventional color flow imaging techniques.......Purpose: Conventional ultrasound methods for acquiring color flow images of the blood motion are limited by a relatively low frame rate and are restricted to only giving velocity estimates along the ultrasound beam direction. To circumvent these limitations, the Plane Wave Excitation (PWE) method...... has been proposed. Material and Methods: The PWE method can estimate the 2D vector velocity of the blood with a high frame rate. Vector velocity estimates are acquired by using the following approach: The ultrasound is not focused during the ultrasound transmission, and a full speckle image...

  18. Estimating 2-D Vector Velocities Using Multidimensional Spectrum Analysis

    DEFF Research Database (Denmark)

    Oddershede, Niels; Løvstakken, Lasse; Torp, Hans;

    2008-01-01

    Wilson (1991) presented an ultrasonic wide-band estimator for axial blood flow velocity estimation through the use of the 2-D Fourier transform. It was shown how a single velocity component was concentrated along a line in the 2-D Fourier space, where the slope was given by the axial velocity...... a minimum variance approach. Based on this plane, the axial and lateral velocity components are estimated. Several phantom measurements, for flow-to-depth angles of 60, 75, and 90 degrees, were performed. Multiple parallel lines were beamformed simultaneously, and 2 different receive apodization schemes....... Later, it was shown that this approach could also be used for finding the lateral velocity component by also including a lateral sampling. A single velocity component would then be concentrated along a plane in the 3-D Fourier space, tilted according to the 2 velocity components. This paper presents 2...

  19. Comparison of Vector Velocity Imaging using Directional Beamforming and Transverse Oscillation for a Convex Array Transducer

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    rig with a stationary, laminar flow, and the volume flow was measured by a MAG 3000 (Danfos, Sønderbog, Denmark) magnetic flow meter for reference. Data were beamformed with an optimized transverse oscillation scheme for the TO VFI, and standard fourth-order estimators were employed for the velocity......Vector velocity imaging can reveal both the magnitude and direction of the blood velocity. Several techniques have been suggested for estimating the velocity, and this paper compares the performance for directional beamforming and transverse oscillation (TO) vector flow imaging (VFI). Data have...... been acquired using the SARUS experimental ultrasound scanner connected to a BK 8820e (BK Medical, Herlev, Denmark) convex array probe with 192 active elements. A duplex sequence with 129 B-mode emissions interleaved with 129 flow emissions has been made. The flow was generated in a recirculating flow...

  20. In-vivo evaluation of three ultrasound vector velocity techniques with MR angiography

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Oddershede, Niels;

    2008-01-01

    In conventional Doppler ultrasound (US) the blood velocity is only estimated along the US beam direction. The estimate is angle corrected assuming laminar flow parallel to the vessel boundaries. As the now in the vascular system never is purely laminar, the velocities estimated with conventional...... Doppler US are always incorrect. Three angle independent vector velocity methods are evaluated in this paper: directional beamforming (DB), synthetic aperture flow imaging (STA) and transverse oscillation (TO). The performances of the three methods were investigated by measuring the stroke volume...... additionally constructed and mean differences for the three comparisons were: DB/MRA = 0.17 ml; STA/MRA = 0.07 ml; TO/MRA = 0.24 ml. The three US vector velocity techniques yield quantitative insight in to flow dynamics and can potentially give the clinician a powerful tool in cardiovascular disease assessment....

  1. Volume Flow in Arteriovenous Fistulas Using Vector Velocity Ultrasound

    DEFF Research Database (Denmark)

    Hansen, Peter Møller; Olesen, Jacob Bjerring; Pihl, Michael Johannes;

    2014-01-01

    Volume flow in arteriovenous fistulas for hemodialysis was measured using the angle-independent ultrasound technique Vector Flow Imaging and compared with flow measurements using the ultrasound dilution technique during dialysis. Using an UltraView 800 ultrasound scanner (BK Medical, Herlev......, Denmark) with a linear transducer, 20 arteriovenous fistulas were scanned directly on the most superficial part of the fistula just before dialysis. Vector Flow Imaging volume flow was estimated with two different approaches, using the maximum and the average flow velocities detected in the fistula. Flow...

  2. Measuring 3D Velocity Vectors using the Transverse Oscillation Method

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2012-01-01

    Experimentally obtained estimates of threedimensional (3D) velocity vectors using the 3D Transverse Oscillation (TO) method are presented. The method employs a 2D transducer and synthesizes two double-oscillating fields in receive to obtain the axial, transverse, and elevation velocity components...... simultaneously. Experimental data are acquired using the ultrasound research scanner SARUS. The double-oscillating TO fields are investigated in an experimental scanning tank setup. The results demonstrate that the created fields only oscillate in the axial plus either the transverse or the elevation direction...

  3. Three dimensional (3d) transverse oscillation vector velocity ultrasound imaging

    DEFF Research Database (Denmark)

    2013-01-01

    An ultrasound imaging system (300) includes a transducer array (302) with a two- dimensional array of transducer elements configured to transmit an ultrasound signal and receive echoes, transmit circuitry (304) configured to control the transducer array to transmit the ultrasound signal so...... as to traverse a field of view, and receive circuitry (306) configured to receive a two dimensional set of echoes produced in response to the ultrasound signal traversing structure in the field of view, wherein the structure includes flowing structures such as flowing blood cells, organ cells etc. A beamformer...... (312) configured to beamform the echoes, and a velocity processor (314) configured to separately determine a depth velocity component, a transverse velocity component and an elevation velocity component, wherein the velocity components are determined based on the same transmitted ultrasound signal...

  4. Improved technique for blood flow velocity measurement using Doppler effect

    Science.gov (United States)

    Valadares Oliveira, Eduardo J.; Nantes Button, Vera L. d. S.; Maia, Joaquim M.; Costa, Eduardo T.

    2002-04-01

    The Doppler velocimeter developed allows to determine the angle between the ultrasonic beam and the velocity vector of the flow, and to calculate the precise blood flow in a vessel. Four piezoelectric transducers constitute the Doppler velocimeter. Three of these transducers are positioned to form an equilateral triangle (base of a pyramid). When these transducers move simultaneously, backward or forward from the initial position, the emitted ultrasonic beams focalize on a position (peak of the pyramid) closer or farther from the transducers faces, according to the depth of the vessel where we intend to measure de flow. The angle between the transducers allows adjusting the height of this pyramid and the position of the focus (where the three beams meet). A forth transducer is used to determine the diameter of the vessel and monitor the position of the Doppler velocimeter relative to the vessel. Simulation results showed that with this technique is possible to accomplish precise measurement of blood flow.

  5. Transverse Oscillations for Phased Array Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2010-01-01

    Medical ultrasound imaging is widely used to visualize blood flow in the human circulatory system. However, conventional methods are angle dependent. The Transverse Oscillation (TO) method is able to measure the lateral velocity component, and it has been demonstrated in in vivo measurements...

  6. Comparison of vector velocity imaging using directional beamforming and transverse oscillation for a convex array transducer

    Science.gov (United States)

    Jensen, Jørgen Arendt

    2014-03-01

    Vector velocity imaging can reveal both the magnitude and direction of the blood velocity. Several techniques have been suggested for estimating the velocity, and this paper compares the performance for directional beam-forming and transverse oscillation (TO) vector flow imaging (VFI). Data have been acquired using the SARUS experimental ultrasound scanner connected to a BK 8820e (BK Medical, Herlev, Denmark) convex array probe with 192 active elements. A duplex sequence with 129 B-mode emissions interleaved with 129 flow emissions has been made. The flow was generated in a recirculating flow rig with a stationary, laminar flow, and the volume flow was measured by a MAG 3000 (Danfos, Sønderbog, Denmark) magnetic flow meter for reference. Data were beamformed with an optimized transverse oscillation scheme for the TO VFI, and standard fourth-order estimators were employed for the velocity estimation. Directional RF lines were beamformed along the flow direction and cross-correlation employed to estimate the velocity magnitude. The velocities were determined for beam-to-flow angles of 60, 75 and 90 degrees. Using 32 emissions the standard deviation relative to the peak velocity for TO estimation was 7.0% at a beam-to-flow angle of 75° . This was 3.8% for directional beamforming and at 60° it was 2.2%. The general improvement, however, comes at an increase by a factor of roughly 11 in the number of calculations for the directional beamformation compared to the TO method.

  7. Using Phased Array for Transverse Oscillation Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Haugaard, Per; Jensen, Jørgen Arendt

    be expanded to phased arrays enabling vector velocity imaging of the heart. Therefore, the performance of the TO estimator has to be evaluated for depths up to 10-15 cm. Methods The TO method is based on creating a double oscillating field. Flow phantoms were simulated with a transverse (90º) parabolic flow...... profile (peak = 1 m/s) and a vessel radius of 5 mm, and ‘scanned’ orthogonal to the flow with a 3.5 MHz phased array transducer. The performance of the lateral velocity estimates were evaluated by calculating the relative mean bias, Br, and relative mean standard deviation, σr, inside the vessel of N=20...

  8. Middle cerebral artery blood velocity during rowing

    DEFF Research Database (Denmark)

    Secher, Niels Henry; Pott, F; Knudsen, L.;

    1997-01-01

    original,arterial blood pressure,central venous pressure,cerebral blood flow, exercise, transcranial Doppler......original,arterial blood pressure,central venous pressure,cerebral blood flow, exercise, transcranial Doppler...

  9. 3-D Vector Velocity Estimation with Row-Column Addressed Arrays

    DEFF Research Database (Denmark)

    Holbek, Simon; Christiansen, Thomas Lehrmann; Rasmussen, Morten Fischer

    2015-01-01

    The concept of 2-D row-column (RC) addressed arrays for 3-D imaging have shown to be an interesting alternative to 2-D matrix array, due to the reduced channel count. However, the properties for RC arrays to estimate blood velocities have never been reported, which is of great importance for a cl......The concept of 2-D row-column (RC) addressed arrays for 3-D imaging have shown to be an interesting alternative to 2-D matrix array, due to the reduced channel count. However, the properties for RC arrays to estimate blood velocities have never been reported, which is of great importance...... for a clinical implementation of this type of array. The aim of this study is, thus, to develop a technique for estimating 3-D vector flow with a RC array using the transverse oscillation (TO) method. The properties are explored both in a simulation study and with a prototype probe for experimental use. In both......-D velocity vector in a 15◦ rotated vessel with a 75◦ beam-to-flow angle. In the experimental setup with a 90◦ beam-to-flow angle, the relative mean biases were (-2.6%, -1.3% , 1.4%) with a relative standard deviation of (5.0%, 5.2%, 1.0%) for the respective transverse, lateral and axial velocity...

  10. Mathematical Relationships Between Two Sets of Laser Anemometer Measurements for Resolving the Total Velocity Vector

    Science.gov (United States)

    Owen, Albert K.

    1993-01-01

    The mathematical relations between the measured velocity fields for the same compressor rotor flow field resolved by two fringe type laser anemometers at different observational locations are developed in this report. The relations allow the two sets of velocity measurements to be combined to produce a total velocity vector field for the compressor rotor. This report presents the derivation of the mathematical relations, beginning with the specification of the coordinate systems and the velocity projections in those coordinate systems. The vector projections are then transformed into a common coordinate system. The transformed vector coordinates are then combined to determine the total velocity vector. A numerical example showing the solution procedure is included.

  11. Ultrasonic 3-D vector flow method for quantitative in vivo peak velocity and flow rate estimation

    DEFF Research Database (Denmark)

    Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed;

    2017-01-01

    Current clinical ultrasound systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the Transverse Oscillation (TO) method, a 32 x 32 element matrix array, and the experimental ultrasound scanner SARUS...... is presented. The aim of this paper is to estimate precise flow rates and peak velocities derived from 3-D vector flow estimates. The emission sequence provides 3-D vector flow estimates at up to 1.145 frames per second in a plane, and was used to estimate 3-D vector flow in a cross sectional image plane....... The method is validated in two phantom studies, where flow rates are measured in a flow-rig, providing a constant parabolic flow, and in a straight-vessel phantom (ø = 8 mm) connected to a flow pump capable of generating time varying waveforms. Flow rates are estimated to be 82.1 ± 2.8 L/min in the flow...

  12. Blood flow velocity in migraine attacks - a transcranial Doppler study

    Energy Technology Data Exchange (ETDEWEB)

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D. (Rijksuniversiteit Leiden (Netherlands))

    1991-05-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs.

  13. Decorrelation-based blood flow velocity estimation: effect of spread of flow velocity, linear flow velocity gradients, and parabolic flow.

    NARCIS (Netherlands)

    Lupotti, F.A.; Steen, A.F.W. van der; Mastik, F.; Korte, C.L. de

    2002-01-01

    In recent years, a new method to measure transverse blood flow, based on the decorrelation of the radio frequency (RF) signals has been developed. In this paper, we investigated the influence of nonuniform flow on the velocity estimation. The decorrelation characteristics of transverse blood flow us

  14. Middle cerebral artery blood velocity and plasma catecholamines during exercise

    DEFF Research Database (Denmark)

    Pott, F; Jensen, K; Hansen, H;

    1996-01-01

    During dynamic exercise, mean blood velocity (Vmean) in the middle cerebral artery (MCA) demonstrates a graded increase to work rate and reflects regional cerebral blood flow. At a high work rate, however, vasoactive levels of plasma catecholamines could mediate vasoconstriction of the MCA...

  15. Analysis of Systolic Backflow and Secondary Helical Blood Flow in the Ascending Aorta Using Vector Flow Imaging

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper

    2016-01-01

    Secondary rotational flow and systolic backflow are seen in the ascending aorta and, in this study, were analyzed with the vector velocity method transverse oscillation. Twenty-five patients were scanned intra-operatively, and the vector velocities were related to estimates of transesophageal...... that backflow is injurious and that secondary flow is a normal flow phenomenon. The study also shows that transverse oscillation can provide new information on blood flow in the ascending aorta....

  16. Maximum Likelihood Blood Velocity Estimator Incorporating Properties of Flow Physics

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Jensen, Jørgen Arendt

    2004-01-01

    The aspect of correlation among the blood velocities in time and space has not received much attention in previous blood velocity estimators. The theory of fluid mechanics predicts this property of the blood flow. Additionally, most estimators based on a cross-correlation analysis are limited...... of simulated and in vivo data from the carotid artery. The estimator is meant for two-dimensional (2-D) color flow imaging. The resulting mathematical relation for the estimator consists of two terms. The first term performs a cross-correlation analysis on the signal segment in the radio frequency (RF......)-data under investigation. The flow physic properties are exploited in the second term, as the range of velocity values investigated in the cross-correlation analysis are compared to the velocity estimates in the temporal and spatial neighborhood of the signal segment under investigation. The new estimator...

  17. Principle and performance of the transverse oscillation vector velocity technique in medical ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Pihl, Michael Johannes; Udesen, Jesper;

    2010-01-01

    to the axial blood velocity. A major drawback is that only the axial velocity component is found. Often the lateral component is most important as blood vessels run parallel to the skin surface. The talk presents the transverse oscillation approach, which also can find the lateral velocity component by using...

  18. Range/velocity limitations for time-domain blood velocity estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1993-01-01

    The traditional range/velocity limitation for blood velocity estimation systems using ultrasound is elucidated. It is stated that the equation is a property of the estimator used, not the actual physical measurement situation, as higher velocities can be estimated by the time domain cross......-correlation approach. It is demonstrated that the time domain technique under certain measurement conditions will yield unsatisfactory results, when trying to estimate high velocities. Various methods to avoid these artifacts using temporal and spatial clustering techniques are suggested. The improvement...

  19. Joint probability discrimination between stationary tissue and blood velocity signals

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Jensen, Jørgen Arendt

    2001-01-01

    In CFM-mode the blood velocity estimates are overlaid onto the B-mode image. The velocity estimation gives non-zero velocity estimates in both the surrounding tissue and the vessels. A discrimination algorithm is needed to determine, which estimates represent blood flow and should be displayed....... This study presents a new statistical discriminator. Investigation of the RF-signals reveals that features can be derived that distinguish the segments of the signal, which do an do not carry information on the blood flow. In this study 4 features, have been determined: (a) the energy content in the segments...... before and after echo-canceling, and (b) the amplitude variations between samples in consecutive RF-signals before and after echo-canceling. The statistical discriminator was obtained by computing the probability density functions (PDFs) for each feature through histogram analysis of data...

  20. Blood velocity estimation using ultrasound and spectral iterative adaptive approaches

    DEFF Research Database (Denmark)

    Gudmundson, Erik; Jakobsson, Andreas; Jensen, Jørgen Arendt;

    2011-01-01

    This paper proposes two novel iterative data-adaptive spectral estimation techniques for blood velocity estimation using medical ultrasound scanners. The techniques make no assumption on the sampling pattern of the emissions or the depth samples, allowing for duplex mode transmissions where B......-mode images are interleaved with the Doppler emissions. Furthermore, the techniques are shown, using both simplified and more realistic Field II simulations as well as in vivo data, to outperform current state-of-the-art techniques, allowing for accurate estimation of the blood velocity spectrum using only 30...

  1. Tissue motion in blood velocity estimation and its simulation

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Torp-Pedersen, Søren; Jensen, Jørgen Arendt;

    1998-01-01

    to the improvement of color flow imaging. Optimization based on in-vivo data is difficult since the blood and tissue signals cannot be accurately distinguished and the correct extend of the vessel under investigation is often unknown. This study introduces a model for the simulation of blood velocity data in which...... times to cover the whole cardiac cycle and a total of 400 independent RF measurements of 950 pulse echo lines were recorded. The motion of the tissue surrounding the hepatic vein from superficial breathing had a peak velocity of 6.2±3.4 mm/s over the cardiac cycle, when averaged over the 10 volunteers...

  2. A New Method for Estimation of Velocity Vectors

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Munk, Peter

    1998-01-01

    , and the standard deviation in the lateral and longitudinal direction. The average performance of the estimates for all angles is: mean velocity 0.99 m/s, longitudinal S.D. 0.015 m/s, and lateral S.D. 0.196 m/s. For flow parallel to the transducer the results are: mean velocity 0.95 m/s, angle 0.10, longitudinal S...

  3. Estimating mechanical blood trauma in a centrifugal blood pump: laser Doppler anemometer measurements of the mean velocity field.

    Science.gov (United States)

    Pinotti, M; Paone, N

    1996-06-01

    A laser Doppler anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.

  4. Real-Time Navigation of Nonholonomic Mobile Robots under Velocity Vector Control

    Directory of Open Access Journals (Sweden)

    Zi-hui Zhang

    2012-09-01

    Full Text Available In this paper, linear navigation law is studied in depth and we suggest an efficient, practical and simple approach for nonholonomic mobile robot navigation under velocity vector control based on the linear navigation law. First of all, an obstacle is equivalent to a velocity vector when detected by a robot’s sensory system according to the relative distant and relative direction between the robot and the obstacle. Then the vector sum of all obstacles’ equivalent velocity vectors (OEVVs and the linear navigation velocity vector (LNVV derived from the linear navigation law drives the robot to reach the desired goal position without colliding with any obstacle in the robot’s workspace. Furthermore, during the process of driving the mobile robot under the resultant velocity vector, a set of strategies for velocity and acceleration constraints (VAC is devised to make kinematic behaviours of the mobile robot more practical. Finally, to validate the effectiveness and superiority, extensive simulation results with no obstacles, a single obstacle and multiple obstacles are provided.

  5. Quantitative blood flow velocity imaging using laser speckle flowmetry

    Science.gov (United States)

    Nadort, Annemarie; Kalkman, Koen; van Leeuwen, Ton G.; Faber, Dirk J.

    2016-04-01

    Laser speckle flowmetry suffers from a debated quantification of the inverse relation between decorrelation time (τc) and blood flow velocity (V), i.e. 1/τc = αV. Using a modified microcirculation imager (integrated sidestream dark field - laser speckle contrast imaging [SDF-LSCI]), we experimentally investigate on the influence of the optical properties of scatterers on α in vitro and in vivo. We found a good agreement to theoretical predictions within certain limits for scatterer size and multiple scattering. We present a practical model-based scaling factor to correct for multiple scattering in microcirculatory vessels. Our results show that SDF-LSCI offers a quantitative measure of flow velocity in addition to vessel morphology, enabling the quantification of the clinically relevant blood flow, velocity and tissue perfusion.

  6. Estimation of velocity vectors in synthetic aperture ultrasound imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Oddershede, Niels

    2006-01-01

    A method for determining both velocity magnitude and angle in a synthetic aperture ultrasound system is described. The approach uses directional beamforming along the flow direction and cross-correlation to determine velocity magnitude. The angle of the flow is determined from the maximum......). The method is also investigated using data measured by an experimental ultrasound scanner from a flow rig. A commercial 128 element 7 MHz linear array transducer is used, and data are measured for flow angles of 60 deg and 90 deg. Data are acquired using the RASMUS experimental ultrasound scanner, which...

  7. Transverse Oscillation Vector Velocity Estimation using a Phased Array Transducer

    DEFF Research Database (Denmark)

    Marcher, Jønne; Pihl, Michael Johannes; Seerup, Gert

    2012-01-01

    The Transverse Oscillation method has shown its commercial feasibility, providing the user with 2D velocity information. Todays implementation on commercial ultrasound platforms only support linear array transducers and are limited in depth. Extending the implementation to a phased array transducer...

  8. Vector velocity estimation using directional beam forming and cross-correlation

    DEFF Research Database (Denmark)

    2000-01-01

    The two-dimensional velocity vector using a pulsed ultrasound field can be determined with the invention. The method uses a focused ultrasound field along the velocity direction for probing the moving medium under investigation. Several pulses are emitted and the focused received fields along...

  9. Group velocity locked vector dissipative solitons in a high repetition rate fiber laser

    CERN Document Server

    Luo, Yiyang; Li, Lei; Sun, Qizhen; Wu, Zhichao; Xu, Zhilin; Fu, Songnian; Zhao, Luming

    2016-01-01

    Vectorial nature of dissipative solitons (DSs) with high repetition rates is studied for the first time in a normal-dispersion fiber laser. Despite the fact that the formed DSs are strongly chirped and the repetition rate is greater than 100 MHz, polarization locked and polarization rotating group velocity locked vector DSs can be formed under 129.3 MHz fundamental mode-locking and 258.6 MHz harmonic mode-locking of the fiber laser, respectively. The two orthogonally polarized components of these vector DSs possess distinctly different central wavelengths and travel together at the same group velocity in the laser cavity, resulting in a gradual spectral edge and small steps on the optical spectra, which can be considered as an auxiliary indicator of the group velocity locked vector DSs.

  10. Some considerations on velocity vector accuracy in dust trajectory analysis

    Science.gov (United States)

    Jackson, A. A.; Zook, Herbert A.

    1994-01-01

    The relative contributions of comets and asteroids to the reservoir of dust in the interplanetary medium is not known. There are direct observations of dust released from comets and there is evidence to associate the IRAS dust bands with possible collisions of asteroids in the main belt. A means towards sorting out the parent sources has been proposed in the establishment of a dust collector in orbit about the Earth. The purpose of such a facility would be to collect not only cosmic dust particles intact but also the state vectors, as they arrive at the detector, the idea being that one may combine analytical laboratory analysis of the physics and chemistry of the captured particles with orbital data in order to help distinguish between bodies and identify parent bodies. The theoretical study of dust particle orbits in the solar system takes on greatly more importance if we use collected trajectory data. The orbital motion of dust when radiation and forces alone are acting is well understood. When gravitational forces due to the planets are included, the motion can become quite complex. In order to characterize the orbits of particles as they crossed the Earth's orbits, a study of the long-time dust orbital evolution was undertaken. We have considered various parameters associated with these dust orbits to see if one may in a general way discriminate between particles evolved from comets and asteroids. We proceed in this study as we have done previously. That is, we considered the dust particles as ideal black bodies, of density 1 gm/cc, spherical, with radii 10-100 microns. Particles of this size are affected by radiation forces, photon pressure, and Poynting-Robertson drag. Account was also taken of solar wind drag, which amounts to about 30 percent of the Poynting-Robertson drag negligible. The gravitational forces due to the planets are included, unlike in our previous study; the planetary orbits are those of true n-body interaction so that the possibility of

  11. 3D Vector Velocity Estimation using a 2D Phased Array

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2011-01-01

    A method to estimate the three dimensional (3D) velocity vector is presented is this paper. 3D velocity vector techniques are needed to measure the full velocity and characterize the complicated flow patterns in the human body. The Transverse Oscillation (TO) method introduces oscillations...... transverse to the ultrasound beam, which enables the estimation of the transverse velocity. To expand the method from 2D to 3D, it is proposed to decouple the velocity estimation into separate estimates of vx, vy, and vz in combination with a 2D phased matrix array. Through simulations the feasibility...... of using the TO method for estimation 3D velocity vectors, and the proposed decoupling is demonstrated. A 64x64 and a 32x32 elements transducer are emulated using Field II. Plug flow with a speed of 1 m/s in a small region is rotated in the XY -plane. A binary flow example with [vx,vy]=[1,0] and [0,1] m...

  12. Alignment of stress, mean wind, and vertical gradient of the velocity vector

    DEFF Research Database (Denmark)

    Berg, Jacob; Mann, Jakob; Patton, E.G.

    2012-01-01

    In many applications in the atmospheric surface layer the turbulent-viscosity hypothesis is applied, i.e. the stress vector can be described through the vertical gradient of velocity. In the atmospheric surface layer, where the Coriolis force and baroclinic effects are considered negligible...

  13. New Developments in Vector Velocity Imaging using the Transverse Oscillation Approach

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Pihl, Michael Johannes; Olesen, Jacob Bjerring;

    2013-01-01

    Vector velocity imaging using the Transverse Oscillation (TO) approach has recently been FDA approved for linear array transducers on a commercial platform. It can now be used clinically for studying the complex flow at e.g. bifurcations, valves, and the heart in real time. Several clinical...

  14. Rolling With Simplified Stream Function Velocity and Strain Rate Vector Inner Product

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The dual-stream function velocity field is reduced in order to analyze two-dimensional plate broadside roll- ing in roughing. The strain rate vector inner product and integral mean value theorem, as well as coqine vector inner product are used respectively in plastic deformation power, friction losses and shear power. A theoretical solution of roll torque and separating force for the rolling is obtained and the calculated results by the solution are compared with those measured in broadside rolling on-line. It shows that both the force and torque calculated are higher than those of measured, but the maximum relative error between them is no more than 11%.

  15. Virtual Velocity Vector-based Offline Collision-free Path Planning of Industrial Robotic Manipulator

    Directory of Open Access Journals (Sweden)

    Fan Ouyang

    2015-09-01

    Full Text Available Currently, industrial robotic manipulators are applied in many manufacturing applications. In most cases, an industrial environment is a cluttered and complex one where moving obstacles may exist and hinder the movement of robotic manipulators. Therefore, a robotic manipulator not only has to avoid moving obstacles, but also needs to fulfill the manufacturing requirements of smooth movement in fixed tact time. Thus, this paper proposes a virtual velocity vector-based algorithm of offline collision-free path planning for manipulator arms in a controlled industrial environment. The minimum distance between a manipulator and a moving obstacle can be maintained at an expected value by utilizing our proposed algorithm with established offline collision-free path-planning and trajectory generating systems. Furthermore, both joint space velocity and Cartesian space velocity of generated time-efficient trajectory are continuous and smooth. In addition, the vector of detour velocity in a 3D environment is determined and depicted. Simulation results indicate that detour velocity can shorten the total task time as well as escaping the local minimal effectively. In summary, our approach can fulfill both safety requirements of collision avoidance of moving obstacles and manufacturing requirements of smooth movement within fixed tact time in an industrial environment.

  16. Prediction of Cerebral Hyperperfusion Syndrome with Velocity Blood Pressure Index

    Directory of Open Access Journals (Sweden)

    Zhi-Chao Lai

    2015-01-01

    Full Text Available Background: Cerebral hyperperfusion syndrome is an important complication of carotid endarterectomy (CEA. An >100% increase in middle cerebral artery velocity (MCAV after CEA is used to predict the cerebral hyperperfusion syndrome (CHS development, but the accuracy is limited. The increase in blood pressure (BP after surgery is a risk factor of CHS, but no study uses it to predict CHS. This study was to create a more precise parameter for prediction of CHS by combined the increase of MCAV and BP after CEA. Methods: Systolic MCAV measured by transcranial Doppler and systematic BP were recorded preoperatively; 30 min postoperatively. The new parameter velocity BP index (VBI was calculated from the postoperative increase ratios of MCAV and BP. The prediction powers of VBI and the increase ratio of MCAV (velocity ratio [VR] were compared for predicting CHS occurrence. Results: Totally, 6/185 cases suffered CHS. The best-fit cut-off point of 2.0 for VBI was identified, which had 83.3% sensitivity, 98.3% specificity, 62.5% positive predictive value and 99.4% negative predictive value for CHS development. This result is significantly better than VR (33.3%, 97.2%, 28.6% and 97.8%. The area under the curve (AUC of receiver operating characteristic: AUC VBI = 0.981, 95% confidence interval [CI] 0.949-0.995; AUC VR = 0.935, 95% CI 0.890-0.966, P = 0.02. Conclusions: The new parameter VBI can more accurately predict patients at risk of CHS after CEA. This observation needs to be validated by larger studies.

  17. Recovering Photospheric Velocities from Vector Magnetograms by using a Three-Dimensional, Fully Magnetohydrodynamic (MHD) Model

    Science.gov (United States)

    Wang, A. H.; Wu, S. T.; Liu, Yang; Hathaway, D.

    2008-01-01

    We introduce a numerical simulation method for recovering the photospheric velocity field from the vector magnetograms. The traditional method is local correlation tracking (LCT) which is based on measuring the relative displacements of features in blocks of pixels between successive white-light images or magnetograms. Within this method, there are a variety of implementations. One of recently developed implementations is induction local correlation tracking (ILCT) as described by Welsch et al. (2004). They employ the normal component of magnetic induction equation as a constraint to assure consistent solutions. Our numerical method uses the fully three-dimensional MHD equations to recover the photospheric velocity field with individual vector magnetograms. We compare our method to the ILCT method using NOAA AR8210 as an example. The differences and similarities are discussed in detail.

  18. Generation of pseudo-high-order group velocity locked vector solitons in fiber lasers

    CERN Document Server

    Jin, Xinxin; Li, Lei; Ge, Yanqi; Luo, Jiaolin; Zhang, Qian; Tang, Dingyuan; Shen, Deyuan; Fu, Songnian; Liu, Deming; Zhao, Luming

    2015-01-01

    We propose and experimentally demonstrate the generation of pseudo-high-order group velocity locked vector solitons (GVLVS) in a fiber laser using a SESAM as the mode locker. With the help of an external all-fiber polarization resolved system, a GVLVS with a two-humped pulse along one polarization while a single-humped pulse along the orthogonal polarization could be obtained. The phase difference between the two humps is 180 degree.

  19. Global tectonics and the plate motion obtained from the ITRF97 station velocity vectors

    Institute of Scientific and Technical Information of China (English)

    MA; Zongjin(马宗晋); REN; Jinwei(任金卫); ZHANG; Jin(张进)

    2003-01-01

    By studying the characteristics of current crustal motion by using the ITRF97 station velocity vectors, it has been found that the ITRF97 station velocity vectors are coherent with those of NUVEL-1A model. Both the ITRF97 and NUVEL-1A velocity vectors show that the northern hemisphere is moving towards northeast and northwest along the North Atlantic Ridge. The Eurasian plate is moving to northeast, east, and southeast. The North American continent is moving to northwest, west, and southwest. The movement in the southern hemisphere is different completely.The movements of African, South American and Indian-Australian plates almost all direct to NE-NNE. The three plates take the South Atlantic Ridge and the Indian Ridge as boundaries, and the movement vectors increase gradually, showing a "lag" type stretch movement as the result of the superimposition of the whole movement of the southern hemisphere and the spreading of ocean ridges. The difference of velocity fields between the northern and southern hemispheres is obvious, and there is a disharmony zone between the two hemispheres. The geological data show that there is an oblique and discontinuous shear zone between the two hemispheres. Along this shear zone, eight large earthquakes (Ms≥7.8) took place from August 1999 to January 2001, while in the same time period, the seismic activities along the western and southern Pacific subduction zone is low, showing the significance of the shear zone on the global scale. The results in this paper indicate the relative shear motion between the northern and southern hemispheres.

  20. Experimental 3-D Vector Velocity Estimation with Row-Column Addressed Arrays

    DEFF Research Database (Denmark)

    Holbek, Simon; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2016-01-01

    Experimental 3-D vector flow estimates obtained with a 62+62 2-D row-column (RC) array with integrated apodization are presented. A transverse oscillation (TO) velocity estimator is implemented on a 3.0 MHz RC array, to yield realtime 3-D vector flow in a cross-sectional scan plane at 750 frames...... rates. The flow rate measured from five cycles is 2.3 mL/stroke ± 0.1 mL/stroke giving a negative 9.7% bias compared to the pump settings. It is concluded that 124 elements are sufficient to estimate 3-D vector flow, if they are positioned in a row-column wise manner....

  1. Tangent-impulse transfer from elliptic orbit to an excess velocity vector

    Institute of Scientific and Technical Information of China (English)

    Zhang Gang; Zhang Xiangyu; Cao Xibin

    2014-01-01

    The two-body orbital transfer problem from an elliptic parking orbit to an excess veloc-ity vector with the tangent impulse is studied. The direction of the impulse is constrained to be aligned with the velocity vector, then speed changes are enough to nullify the relative velocity. First, if one tangent impulse is used, the transfer orbit is obtained by solving a single-variable function about the true anomaly of the initial orbit. For the initial circular orbit, the closed-form solution is derived. For the initial elliptic orbit, the discontinuous point is solved, then the initial true anomaly is obtained by a numerical iterative approach; moreover, an alternative method is proposed to avoid the singularity. There is only one solution for one-tangent-impulse escape trajectory. Then, based on the one-tangent-impulse solution, the minimum-energy multi-tangent-impulse escape trajectory is obtained by a numerical optimization algorithm, e.g., the genetic method. Finally, several examples are provided to validate the proposed method. The numerical results show that the minimum-energy multi-tangent-impulse escape trajectory is the same as the one-tangent-impulse trajectory.

  2. Angular velocity estimation based on star vector with improved current statistical model Kalman filter.

    Science.gov (United States)

    Zhang, Hao; Niu, Yanxiong; Lu, Jiazhen; Zhang, He

    2016-11-20

    Angular velocity information is a requisite for a spacecraft guidance, navigation, and control system. In this paper, an approach for angular velocity estimation based merely on star vector measurement with an improved current statistical model Kalman filter is proposed. High-precision angular velocity estimation can be achieved under dynamic conditions. The amount of calculation is also reduced compared to a Kalman filter. Different trajectories are simulated to test this approach, and experiments with real starry sky observation are implemented for further confirmation. The estimation accuracy is proved to be better than 10-4  rad/s under various conditions. Both the simulation and the experiment demonstrate that the described approach is effective and shows an excellent performance under both static and dynamic conditions.

  3. Predicting stroke outcome using DCE-CT measured blood velocity

    Science.gov (United States)

    Oosterbroek, Jaap; Bennink, Edwin; Dankbaar, Jan Willem; Horsch, Alexander D.; Viergever, Max A.; Velthuis, Birgitta K.; de Jong, Hugo W. A. M.

    2015-03-01

    CT plays an important role in the diagnosis of acute stroke patients. Dynamic contrast enhanced CT (DCE-CT) can estimate local tissue perfusion and extent of ischemia. However, hemodynamic information of the large intracranial vessels may also be obtained from DCE-CT data and may contain valuable diagnostic information. We describe a novel method to estimate intravascular blood velocity (IBV) in large cerebral vessels using DCE-CT data, which may be useful to help predict stroke outcome. DCE-CT scans from 34 patients with isolated M1 occlusions were included from a large prospective multi-center cohort study of patients with acute ischemic stroke. Gaussians fitted to the intravascular data yielded the time-to-peak (TTP) and cerebral-blood-volume (CBV). IBV was computed by taking the inverse of the TTP gradient magnitude. Voxels with a CBV of at least 10% of the CBV found in the arterial input function were considered part of a vessel. Mid-sagittal planes were drawn manually and averages of the IBV over all vessel-voxels (arterial and venous) were computed for each hemisphere. Mean-hemisphere IBV differences, mean-hemisphere TTP differences, and hemisphere vessel volume differences were used to differentiate between patients with good and bad outcome (modified Rankin Scale score <3 versus ≥3 at 90 days) using ROC analysis. AUCs from the ROC for IBV, TTP, and vessel volume were 0.80, 0.67 and 0.62 respectively. In conclusion, IBV was found to be a better predictor of patient outcome than the parameters used to compute it and may be a promising new parameter for stroke outcome prediction.

  4. 'Snap-shot' velocity vector mapping using echo-planar imaging.

    Science.gov (United States)

    Tayler, Alexander B; Sederman, Andrew J; Newling, Benedict; Mantle, Mick D; Gladden, Lynn F

    2010-06-01

    A 'snap-shot' ultra-fast MRI velocimetry technique based upon the echo-planar imaging (EPI) pulse sequence is presented. The new technique is an extension of the GERVAIS pulse sequence previously developed by Sederman et al. (2004) and is capable of acquiring both reference and velocity encoded phase maps following a single excitation for generation of three-component velocity vectors in under 125 ms. This approach allows velocity images of systems with a dynamic, non-periodic geometry to be obtained by MRI. The technique proved to be accurate within 5% error by comparison with Poiseuille flow in a pipe and for the transverse plane flow field in a Couette cell. It was further applied to obtain the velocity field around an impeller in a stirred vessel; an unsteady yet periodic system which otherwise could only be studied by triggered acquisitions. Good agreement was evident between the present technique and triggered conventional velocity encoded pulse sequences. Finally, new experimental data attainable only by the new sequence is demonstrated as the flow field within a mobile droplet of oil is captured as it rises through a column of water. The technique promises to be highly useful in velocimetric measurements of dynamic, non-periodic systems, and in particular for the characterisation of multiphase flow systems.

  5. Generation of High-order Group-velocity-locked Vector Solitons

    CERN Document Server

    Jin, X X; Zhang, Q; Li, L; Tang, D Y; Shen, D Y; Fu, S N; Liu, D M; Zhao, L M

    2015-01-01

    We report numerical simulations on the high-order group-velocity-locked vector soliton (GVLVS) generation based on the fundamental GVLVS. The high-order GVLVS generated is characterized with a two-humped pulse along one polarization while a single-humped pulse along the orthogonal polarization. The phase difference between the two humps could be 180 degree. It is found that by appropriate setting the time separation between the two components of the fundamental GVLVS, the high-order GVLVS with different pulse width and pulse intensity could be obtained. 1+2 and 2+2 type high-order GVLVS could be either obtained.

  6. Non-invasive Estimation of Pressure Changes along a Streamline using Vector Velocity Ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Villagómez Hoyos, Carlos Armando; Traberg, Marie Sand;

    2015-01-01

    estimator is evaluated by comparing its results to a 3-D numerical simulation model. The study showed pressure drops across the constricted phantom varying from -5 Pa to 7 Pa with a standard deviation of 4%. The proposed method had a normalised rootmean-square error of 10% in reference to the simulation......A non-invasive method for estimating pressure changes along a streamline using ultrasound is presented. The suggested method estimates pressure gradients from 2-D vector velocity fields. Changes in pressure are derived using a model based on the Navier-Stokes equations. Scans of a carotid...

  7. Force, Velocity, and Work: The Effects of Different Contexts on Students' Understanding of Vector Concepts Using Isomorphic Problems

    Science.gov (United States)

    Barniol, Pablo; Zavala, Genaro

    2014-01-01

    In this article we compare students' understanding of vector concepts in problems with no physical context, and with three mechanics contexts: force, velocity, and work. Based on our "Test of Understanding of Vectors," a multiple-choice test presented elsewhere, we designed two isomorphic shorter versions of 12 items each: a test with no…

  8. Arterial secondary blood flow patterns visualized with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Hansen, Jens Munk

    2011-01-01

    This study presents the first quantification and visualisation of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study...

  9. A new maximum likelihood blood velocity estimator incorporating spatial and temporal correlation

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Jensen, Jørgen Arendt

    2001-01-01

    The blood flow in the human cardiovascular system obeys the laws of fluid mechanics. Investigation of the flow properties reveals that a correlation exists between the velocity in time and space. The possible changes in velocity are limited, since the blood velocity has a continuous profile in time...... of the observations gives a probability measure of the correlation between the velocities. Both the MLE and the STC-MLE have been evaluated on simulated and in-vivo RF-data obtained from the carotid artery. Using the MLE 4.1% of the estimates deviate significantly from the true velocities, when the performance...

  10. A Transverse Oscillation Approach for Estimation of Three-Dimensional Velocity Vectors, Part I: Concept and Simulation Study

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2014-01-01

    A method for 3-D velocity vector estimation us - ing transverse oscillations is presented. The method employs a 2-D transducer and decouples the velocity estimation into three orthogonal components, which are estimated simultane - ously and from the same data. The validity of the method is invest......A method for 3-D velocity vector estimation us - ing transverse oscillations is presented. The method employs a 2-D transducer and decouples the velocity estimation into three orthogonal components, which are estimated simultane - ously and from the same data. The validity of the method...... also reveals, that the velocity estimation breaks down with an SNR between −6 and −3 dB. In terms of computational load, the estimation of the three velocity components requires 0.75 billion floating point operations per second (0.75 Gflops) for a realistic setup. This is well within the capability...

  11. Correlation between myocardial dysfunction and perfusion impairment in diabetic rats with velocity vector imaging and myocardial contrast echocardiography.

    Science.gov (United States)

    Wei, Zhangrui; Zhang, Haibin; Su, Haili; Zhu, Ting; Zhu, Yongsheng; Zhang, Jun

    2012-11-01

    The purpose of this study was to investigate whether myocardial systolic dysfunction and perfusion impairment occur in diabetic rats, and to assess their relationship using velocity vector imaging (VVI) and myocardial contrast echocardiography (MCE). Forty-six rats were randomly divided into either control or the diabetes mellitus (DM) groups. DM was induced by intraperitoneal administration of streptozotocin. Twelve weeks later, 39 survival rats underwent VVI and MCE in short-axis view at the middle level of the left ventricle, both at rest and after dipyridamole stress. VVI-derived contractile parameters included peak systolic velocity (Vs ), circumferential strain (εc ), strain rate (SRc ), and their reserves. MCE-derived perfusion parameters consisted of myocardial blood flow (MBF) and myocardial flow reserve (MFR). At rest, SRc in the DM group was significantly lower than in the control group, Vs , εc , and MBF did not differ significantly between groups. After dipyridamole stress, all VVI parameters and their reserves in the DM group were significantly lower than those in the control group, MBF and MFR were substantially lower than those in the control group, too. Meanwhile, significant correlations between VVI parameter reserves and MFR were observed in the DM group. Both myocardial systolic function and perfusion were impaired in DM rats. Decreased MFR could be an important contributor to the reduction in myocardial contractile reserve.

  12. Assessment of left ventricular global and regional longitudinal function in fetus using velocity vector imaging

    Directory of Open Access Journals (Sweden)

    Rui-xia TIAN

    2013-09-01

    Full Text Available Objective To measure the left ventricle global and segmental longitudinal strain, strain rate, and peak velocity in normal fetuses using velocity vector imaging (VVI for the assessment of the left ventricular function. Methods Detailed prenatal echocardiographic examinations were performed in 53 normal fetuses. Digital dynamic four-chamber views were collected and analyzed offline. In the four-chamber view, the interventricular septum and left ventricular lateral wall were divided into basal, middle and apical segments, in a total of six segments. Endocardial tracing began at the edge of the anterior mitral valve annulus, along endocardium of interventricular septum, extended to the ventricular apex, and returned to posterior mitral valve annulus along lateral ventricular wall edge. The global and segmental longitudinal strain, strain rate and peak velocity of the interventricular septum and left ventricular lateral wall were measured, the global function was calculated by an average of all segments. Segmental measurements were compared to global results. Results Fifty-three fetuses were enrolled in this study, and the VVI analysis was successful in 49, the success rate was 92.4%. The global left ventricular strain was –13.72%±3.99%, and the strain rate was –2.59±0.44/s and 2.43±0.38/s in systole and diastole respectively. No difference was found between segmental and global ventricular strain and strain rate. The left global ventricular peak velocity was 1.68±0.46cm/s and 1.51±0.41cm/s in systole and diastole respectively. The peak segmental velocity in systole and diastole decreased from the base of interventricular septum and lateral wall to ventricular apex. The global left ventricular peak velocity was significantly different from the peak velocity of apical and basal segments (P<0.05. Conclusions Measurement of global left ventricular longitudinal strain, strain rate and peak velocity is feasible in fetuses by using VVI

  13. Data adaptive estimation of transversal blood flow velocities

    DEFF Research Database (Denmark)

    Pirnia, E.; Jakobsson, A.; Gudmundson, E.

    2014-01-01

    , posing natural difficulties due to the complex behaviour of blood flow, and due to the natural orientation of most blood vessels. Recently, a transversal modulation scheme was introduced to induce also an oscillation along the transversal direction, thereby allowing for the measurement of also...... the transversal blood flow. In this paper, we propose a novel data-adaptive blood flow estimator exploiting this modulation scheme. Using realistic Field II simulations, the proposed estimator is shown to achieve a notable performance improvement as compared to current state-of-the-art techniques....

  14. Middle cerebral artery blood velocity and cerebral blood flow and O2 uptake during dynamic exercise

    DEFF Research Database (Denmark)

    Madsen, P L; Sperling, B K; Warming, T

    1993-01-01

    Results obtained by the 133Xe clearance method with external detectors and by transcranial Doppler sonography (TCD) suggest that dynamic exercise causes an increase of global average cerebral blood flow (CBF). These data are contradicted by earlier data obtained during less-well-defined conditions....... To investigate this controversy, we applied the Kety-Schmidt technique to measure the global average levels of CBF and cerebral metabolic rate of oxygen (CMRO2) during rest and dynamic exercise. Simultaneously with the determination of CBF and CMRO2, we used TCD to determine mean maximal flow velocity...... in the middle cerebral artery (MCA Vmean). For values of CBF and MCA Vmean a correction for an observed small drop in arterial PCO2 was carried out. Baseline values for global CBF and CMRO2 were 50.7 and 3.63 ml.100 g-1.min-1, respectively. The same values were found during dynamic exercise, whereas a 22% (P

  15. In vivo lateral blood flow velocity measurement using speckle size estimation.

    Science.gov (United States)

    Xu, Tiantian; Hozan, Mohsen; Bashford, Gregory R

    2014-05-01

    In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is "smeared") if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method

  16. Complex blood flow quantification using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Per, Haugaard;

    A new method to define and quantify complex blood flow is presented. The standard deviations of real-time in vivo vector flow angle estimates are used. Using vector flow ultrasound imaging both carotid bifurcations of two healthy volunteers were scanned. Scanning was performed with a 7.6 MHz linear...... patterns can be visualised and quantified with real-time in vivo vector flow. Good agreement between visual evaluation and the quantitative method has been shown. A standard deviation of vector angle estimates above 30 is proposed to define complex blood flow....

  17. Navigation Doppler Lidar Sensor for Precision Altitude and Vector Velocity Measurements Flight Test Results

    Science.gov (United States)

    Pierrottet, Diego F.; Lockhard, George; Amzajerdian, Farzin; Petway, Larry B.; Barnes, Bruce; Hines, Glenn D.

    2011-01-01

    An all fiber Navigation Doppler Lidar (NDL) system is under development at NASA Langley Research Center (LaRC) for precision descent and landing applications on planetary bodies. The sensor produces high resolution line of sight range, altitude above ground, ground relative attitude, and high precision velocity vector measurements. Previous helicopter flight test results demonstrated the NDL measurement concepts, including measurement precision, accuracies, and operational range. This paper discusses the results obtained from a recent campaign to test the improved sensor hardware, and various signal processing algorithms applicable to real-time processing. The NDL was mounted in an instrumentation pod aboard an Erickson Air-Crane helicopter and flown over vegetation free terrain. The sensor was one of several sensors tested in this field test by NASA?s Autonomous Landing and Hazard Avoidance Technology (ALHAT) project.

  18. Changes in left atrial deformation in hypertrophic cardiomyopathy: Evaluation by vector velocity imaging

    Directory of Open Access Journals (Sweden)

    Hala Mahfouz Badran

    2012-12-01

    Full Text Available Objectives: Hypertrophic cardiomyopathy (HCM represents a generalized myopathic process affecting both ventricular and atrial myocardium. We assessed the global and regional left atrial (LA function and its relation to left ventricular (LV mechanics and clinical status in patients with HCM using Vector Velocity Imaging (VVI. Methods: VVI of the LA and LV was acquired from apical four- and two-chamber views of 108 HCM patients (age 40±19years, 56.5% men and 33 healthy subjects, all had normal LV systolic function. The LA subendocardium was traced to obtain atrial volumes, ejection fraction, velocities, and strain (ɛ/strain rate (SR measurements. Results: Left atrial reservoir (ɛsys,SRsys and conduit (early diastolic SRe function were significantly reduced in HCM compared to controls (P-1.8s-1 was 81% sensitive and 30% specific, SRa>-1.5s-1 was 73% sensitive and 40% specific. By multivariate analysis global LVɛsys and LV septal thickness are independent predictors for LAɛsys, while end systolic diameter is the only independent predictor for SRsys, P<.001. Conclusion: Left atrial reservoir and conduit function as measured by VVI were significantly impaired while contractile function was preserved among HCM patients. Left atrial deformation was greatly influenced by LV mechanics and correlated to severity of phenotype.

  19. Effects of friction massage of the popliteal fossa on blood flow velocity of the popliteal vein

    Science.gov (United States)

    Iwamoto, Koji; Mizukami, Masafumi; Asakawa, Yasutsugu; Endo, Yusuke; Takata, Yuichi; Yoshikawa, Kenichi; Yoshio, Masaharu

    2017-01-01

    [Purpose] Friction massage (friction) of the popliteal fossa is provided for the purpose of relieving pain related to circulatory disorders by improving venous flow in the lower legs. The purpose of this study is to verify the effects of enhancing the venous flow based on measuring the blood flow velocity of the popliteal vein before and after providing friction to the patients. [Subjects and Methods] Fifteen healthy male university students participated in the study. The Doppler ultrasonography (DU) was used to measure the blood flow velocity of the popliteal vein, in order to verify the effects of enhancing the venous flow by comparing the measured values before and after a friction massage. [Results] The result of comparing the blood flow velocity before and after providing friction showed that there was a significant increase after friction. [Conclusion] This study proved that friction to the popliteal fossa is effectively enhances venous flow by increasing the blood flow velocity in the popliteal vein.

  20. Quantification of complex blood flow using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per;

    2010-01-01

    A quantitative method for distinguishing complex from non-complex flow patterns in ultrasound is presented. A new commercial BK Medical ultrasound scanner uses the Transverse Oscillation vector flow technique for visualising flow patterns in real-time. In vivo vector flow data of the blood flow...

  1. MR-based coronary artery blood velocity measurements in patients without coronary artery disease

    Energy Technology Data Exchange (ETDEWEB)

    Schiemann, M.; Esmaeili, A.; Vogl, T.J. [Johann Wolfgang Goethe-University, Institute of Diagnostic and Interventional Radiology University Hospital, Frankfurt am Main (Germany); Bakhtiary, F.; Moritz, A. [University HospitalJohann Wolfgang Goethe-University, Department of Thoracic and Cardiovascular Surgery, Frankfurt am Main (Germany); Hietschold, V. [University Hospital Carl Gustav Carus Technical University Dresden, Institute of Diagnostic Radiology, Dresden (Germany); Koch, A.; Abolmaali, N.D. [Johann Wolfgang Goethe-University, Institute of Diagnostic and Interventional Radiology University Hospital, Frankfurt am Main (Germany); University Hospital Carl Gustav Carus Techinical University Dresden, ZIK OncoRay - Molecular Imaging, Dresden (Germany); Ackermann, H. [Johann Wolfgang Goethe University, Department for Biomathematics, Frankfurt am Main (Germany)

    2006-05-15

    To evaluate the feasibility of MR-based coronary blood velocity measurements (MRvenc) in patients without coronary artery disease (CAD). Eighty-three patients with angiographically excluded CAD received MRvenc of the proximal segments of both coronary arteries (CAs). Using a retrospectively ECG-gated breath-hold phase-contrast FLASH sequence with high temporal resolution, flow data were technically acquirable in 137/166 (83%) CAs. Quantification and analysis of blood velocities in systole and diastole of both CAs were performed. Biphasic velocity profiles were found in 83/100 CAs. Median systolic and diastolic velocities differed significantly in LCA (19 cm/s, 24 cm/s; P<0.0001) and RCAs (14 cm/s, 16 cm/s; P<0.01). The diastolic/systolic velocity ratio was calculated in LCAs and RCAs with a median of 1.3 and 1.1, respectively. The velocity profiles of the remaining CAs were monophasic (17 CAs) or revealed severe alterations of the physiologic velocity profile with reduced flow undulations and steady velocities (37 CAs). Optimized clinical MRvenc is feasible to quantify blood velocities in the CAs. Potential indications are (1) non-invasive monitoring of patients after aortic valve reconstruction as well as (2) detection of asymptomatic CAD patients. (orig.)

  2. Vector velocity volume flow estimation: Sources of error and corrections applied for arteriovenous fistulas.

    Science.gov (United States)

    Jensen, Jonas; Olesen, Jacob Bjerring; Stuart, Matthias Bo; Hansen, Peter Møller; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

    2016-08-01

    A method for vector velocity volume flow estimation is presented, along with an investigation of its sources of error and correction of actual volume flow measurements. Volume flow errors are quantified theoretically by numerical modeling, through flow phantom measurements, and studied in vivo. This paper investigates errors from estimating volumetric flow using a commercial ultrasound scanner and the common assumptions made in the literature. The theoretical model shows, e.g. that volume flow is underestimated by 15%, when the scan plane is off-axis with the vessel center by 28% of the vessel radius. The error sources were also studied in vivo under realistic clinical conditions, and the theoretical results were applied for correcting the volume flow errors. Twenty dialysis patients with arteriovenous fistulas were scanned to obtain vector flow maps of fistulas. When fitting an ellipsis to cross-sectional scans of the fistulas, the major axis was on average 10.2mm, which is 8.6% larger than the minor axis. The ultrasound beam was on average 1.5mm from the vessel center, corresponding to 28% of the semi-major axis in an average fistula. Estimating volume flow with an elliptical, rather than circular, vessel area and correcting the ultrasound beam for being off-axis, gave a significant (p=0.008) reduction in error from 31.2% to 24.3%. The error is relative to the Ultrasound Dilution Technique, which is considered the gold standard for volume flow estimation for dialysis patients. The study shows the importance of correcting for volume flow errors, which are often made in clinical practice.

  3. Retinal blood flow velocity in patients with active uveitis using the retinal function imager

    Institute of Scientific and Technical Information of China (English)

    FENG Xing; Kedhar Sanjay; Bhoomibunchoo Chavakij

    2013-01-01

    Background Previous studies suggest a link between macular edema and retinal blood flow velocity (RBFV).The effects of inflammation in the retinal blood vessels are not clearly understood.We want to evaluate the differences in retinal blood flow velocities of patients with active uveitis and healthy controls using the retinal function imager (RFI)and determine the correlation between retinal blood flow veiocity and central macular thickness in uveitis patients.Methods Twenty-eight eyes of 24 patients with active anterior uveitis and 51 eyes of 51 normal control subjects were enrolled.Retinal blood flow velocities evaluated by RFI and central macular thickness evaluated by optical coherence tomography (SLO-OCT) were obtained.Differences among the groups were assessed using Stata statistical software.Results Ten eyes had uveitic cystoid macular edema (CME).Median (first quartile,third quartile) venous velocity for uveitic eyes with CME,uveitic eyes without CME,and controls were 2.09 (1.92,2.44),2.64 (2.32,2.86),and 2.82 (2.39,3.53) mm/s respectively.Median (first and quartile) arterial velocity for uveitic eyes with CME,uveitic eyes without CME,and controls were 3.79 (3.61,4.09),3.46 (2.86,4.12),and 3.93 (3.35,4.65) mm/s.Uveitic eyes with CME had significantly lower venous velocity than controls (P=0.044).There was a strong linear relationship between venous velocity and central retinal thickness (P=-0.007).Conclusions Retinal venous velocities were significantly decreased in eyes with uveitic CME relative to controls.Decreased venous velocity was correlated with increased central retinal thickness in uveitic eyes.

  4. Vectores

    OpenAIRE

    2016-01-01

    Documento que contiene la explicación sobre las temáticas de Sistemas coordenados, Cantidades vectoriales y escalares, Algunas propiedades de los vectores, Componentes de un vector y vectores unitarios

  5. Dynamical equations for the vector potential and the velocity potential in incompressible irrotational Euler flows: a refined Bernoulli theorem.

    Science.gov (United States)

    Ohkitani, Koji

    2015-09-01

    We consider incompressible Euler flows in terms of the stream function in two dimensions and the vector potential in three dimensions. We pay special attention to the case with singular distributions of the vorticity, e.g., point vortices in two dimensions. An explicit equation governing the velocity potentials is derived in two steps. (i) Starting from the equation for the stream function [Ohkitani, Nonlinearity 21, T255 (2009)NONLE50951-771510.1088/0951-7715/21/12/T02], which is valid for smooth flows as well, we derive an equation for the complex velocity potential. (ii) Taking a real part of this equation, we find a dynamical equation for the velocity potential, which may be regarded as a refinement of Bernoulli theorem. In three-dimensional incompressible flows, we first derive dynamical equations for the vector potentials which are valid for smooth fields and then recast them in hypercomplex form. The equation for the velocity potential is identified as its real part and is valid, for example, flows with vortex layers. As an application, the Kelvin-Helmholtz problem has been worked out on the basis the current formalism. A connection to the Navier-Stokes regularity problem is addressed as a physical application of the equations for the vector potentials for smooth fields.

  6. Micro-particle image velocimetry for velocity profile measurements of micro blood flows.

    Science.gov (United States)

    Pitts, Katie L; Fenech, Marianne

    2013-04-25

    Micro-particle image velocimetry (μPIV) is used to visualize paired images of micro particles seeded in blood flows. The images are cross-correlated to give an accurate velocity profile. A protocol is presented for μPIV measurements of blood flows in microchannels. At the scale of the microcirculation, blood cannot be considered a homogeneous fluid, as it is a suspension of flexible particles suspended in plasma, a Newtonian fluid. Shear rate, maximum velocity, velocity profile shape, and flow rate can be derived from these measurements. Several key parameters such as focal depth, particle concentration, and system compliance, are presented in order to ensure accurate, useful data along with examples and representative results for various hematocrits and flow conditions.

  7. Effects of magnetic field and Hall current to the blood velocity and LDL transfer

    Science.gov (United States)

    Abdullah, I.; Naser, N.; Talib, A. H.; Mahali, S.

    2015-09-01

    The magnetic field and Hall current effects have been considered on blood velocity and concentration of low-density lipoprotein (LDL). It is important to observe those effects to the flowing blood in a stenosed artery. The analysis from the obtained results may be useful to some clinical procedures, such as MRI, where the radiologists may have more information in the investigations before cardiac operations could be done. In this study, the uniform magnetic field and Hall current are applied to the Newtonian blood flow through an artery having a cosine-shaped stenosis. The governing equations are coupled with mass transfer and solved employing a finite difference Marker and Cell (MAC) method with an appropriate initial and boundary conditions. The graphical results of velocity profiles and LDL concentration are presented in this paper and the results show that the velocity increases and concentration decreases as Hall parameter increased.

  8. Simulation development and evaluation of an improved longitudinal velocity vector control wheel steering mode and electronic display format

    Science.gov (United States)

    Steinmetz, G. G.

    1980-01-01

    Using simulation, an improved longitudinal velocity vector control wheel steering mode and an improved electronic display format for an advanced flight system were developed and tested. Guidelines for the development phase were provided by test pilot critique summaries of the previous system. The results include performances from computer generated step column inputs across the full airplane speed and configuration envelope, as well as piloted performance results taken from a reference line tracking task and an approach to landing task conducted under various environmental conditions. The analysis of the results for the reference line tracking and approach to landing tasks indicates clearly detectable improvement in pilot tracking accuracy with a reduction in physical workload. The original objectives of upgrading the longitudinal axis of the velocity vector control wheel steering mode were successfully met when measured against the test pilot critique summaries and the original purpose outlined for this type of augment control mode.

  9. Involvement of calcitonin gene-related peptide in migraine: regional cerebral blood flow and blood flow velocity in migraine patients

    DEFF Research Database (Denmark)

    Lassen, L.H.; Jacobsen, V.B.; Haderslev, P.A.

    2008-01-01

    g/min) or placebo for 20 min was studied in 12 patients with migraine without aura outside attacks. Xenon-133 inhalation SPECT-determined regional cerebral blood flow (rCBF) and transcranial Doppler (TCD)-determined blood velocity (V-mean) in the middle cerebral artery (MCA), as well as the heart......Calcitonin gene-related peptide (CGRP)-containing nerves are closely associated with cranial blood vessels. CGRP is the most potent vasodilator known in isolated cerebral blood vessels. CGRP can induce migraine attacks, and two selective CGRP receptor antagonists are effective in the treatment...... of migraine attacks. It is therefore important to investigate its mechanism of action in patients with migraine. We here investigate the effects of intravenous human alpha-CGRP (h alpha CGRP) on intracranial hemodynamics. In a double-blind, cross-over study, the effect of intravenous infusion of haCGRP (2 mu...

  10. Artifacts in blood velocity estimation using ultrasound and cross-correlation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1994-01-01

    Estimation of blood velocities using ultrasound and time-domain cross-correlation is investigated. The measurement principle is introduced, and the basic properties of the cross-correlation function are discussed. Expressions for the variance of the estimates of the peak location are given, showing...

  11. An Analysis of Pulsed Wave Ultrasound Systems for Blood Velocity Estimation

    DEFF Research Database (Denmark)

    Jensen, J. A.

    1995-01-01

    Pulsed wave ultrasound systems can be used for determining blood's velocity non-invasively in the body. A region of interest is selected, and the received signal is range gated to measure data from the region. One complex sample value is acquired for each pulse emission after complex demodulation...

  12. Cerebral blood flow velocity changes during upright positioning in bed after acute stroke : An observational study

    NARCIS (Netherlands)

    Aries, Marcel J; Elting, Jan Willem; Stewart, Roy; De Keyser, Jacques; Kremer, Berry; Vroomen, Patrick

    2013-01-01

    Objectives: National guidelines recommend mobilisation in bed as early as possible after acute stroke. Little is known about the influence of upright positioning on real-time cerebral flow variables in patients with stroke. We aimed to assess whether cerebral blood flow velocity (CBFV) changes signi

  13. Influence of caffeine and caffeine withdrawal on headache and cerebral blood flow velocities

    NARCIS (Netherlands)

    Couturier, EGM; Laman, DM; vanDuijn, MAJ; vanDuijn, H

    1997-01-01

    Caffeine consumption may cause headache, particularly migraine. Its withdrawal also produces headaches and may be related to weekend migraine attacks. Transcranial Doppler sonography (TCD) has shown changes in cerebral blood flow velocities (BFV) during and between attacks of migraine. In order to e

  14. Intracoronary Blood Flow Velocity and Transstenotic Pressure Drop in an Awake Human Being During Coronary Vasodilation

    NARCIS (Netherlands)

    F. Zijlstra (Felix); P.W.J.C. Serruys (Patrick)

    1988-01-01

    textabstractThe pressure drop over a coronary stenosis and the intracoronary Doppler blood flow velocity were measured at rest and during coronary vasodilation. We report the first observation that confirms the validity of fluid dynamic equations to describe the hemodynamics of a coronary stenosis b

  15. Blood velocity estimation using spatio-temporal encoding based on frequency division approach

    DEFF Research Database (Denmark)

    Gran, Fredrik; Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2005-01-01

    spectral support. By assigning one band to one virtual source, all virtual sources can be excited simultaneously. The received echoes are beamformed using Synthetic Transmit Aperture beamforming. The velocity of the moving blood is estimated using a cross- correlation estimator. The simulation tool Field...

  16. Effects of Wrist Posture and Fingertip Force on Median Nerve Blood Flow Velocity

    Science.gov (United States)

    Wilson, Katherine E.; Tat, Jimmy

    2017-01-01

    Purpose. The purpose of this study was to assess nerve hypervascularization using high resolution ultrasonography to determine the effects of wrist posture and fingertip force on median nerve blood flow at the wrist in healthy participants and those experiencing carpal tunnel syndrome (CTS) symptoms. Methods. The median nerves of nine healthy participants and nine participants experiencing symptoms of CTS were evaluated using optimized ultrasonography in five wrist postures with and without a middle digit fingertip press (0, 6 N). Results. Both wrist posture and fingertip force had significant main effects on mean peak blood flow velocity. Blood flow velocity with a neutral wrist (2.87 cm/s) was significantly lower than flexed 30° (3.37 cm/s), flexed 15° (3.27 cm/s), and extended 30° (3.29 cm/s). Similarly, median nerve blood flow velocity was lower without force (2.81 cm/s) than with force (3.56 cm/s). A significant difference was not found between groups. Discussion. Vascular changes associated with CTS may be acutely induced by nonneutral wrist postures and fingertip force. This study represents an early evaluation of intraneural blood flow as a measure of nerve hypervascularization in response to occupational risk factors and advances our understanding of the vascular phenomena associated with peripheral nerve compression.

  17. In vivo μPIV measurements of blood velocity in small vessels of a rat model

    Science.gov (United States)

    Leong, Chia Min; Russell, John; Connor, Nadine; Honkanen, Markus; Wei, Timothy

    2009-11-01

    Aging-related muscular changes have been shown to affect voice production. There is correlation between muscular changes and changes in capillary hemodynamics and structure with aging. Alterations in oxygen transport to cells and tissues at the capillary level has been hypothesized as one of the key factors that causes muscular changes thus voice production. Since oxygen transport is related to hemodynamics, we start by measuring blood velocity in capillaries of cremaster muscle of a living rat. The μPIV technique is adapted for measuring blood velocity where red blood cells are used as `seeding particles'. The accuracy of the μPIV measurements are determined by comparison with results obtained using other techniques such as particle tracking velocimetry (PTV). Finally, challenges in measuring flow through three-dimensional larynx geometry will be discussed.

  18. Estimation of the blood velocity spectrum using a recursive lattice filter

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Buelund, Claus; Jørgensen, Allan;

    1996-01-01

    In medical ultrasound the blood velocity distribution in a vessel can be found by emitting a pulsed field into the patient. The field is then scattered by the tissues and the red blood cells, and a single complex sample set is acquired at the depth of interest for each pulse emitted. The signals...... acquired for showing the blood velocity distribution are inherently non-stationary, due to the pulsatility of the flow. All current signal processing schemes assume that the signal is stationary within the window of analysis, although this is an approximation. In this paper a recursive least...... with the actual distributions that always will be smooth. Setting the exponential decay factor to 0.99 gives satisfactory results for in-vivo data from the carotid artery. The filter can easily be implemented using a standard fixed-point signal processing chip for real-time processing...

  19. Vectors

    DEFF Research Database (Denmark)

    Boeriis, Morten; van Leeuwen, Theo

    2017-01-01

    This article revisits the concept of vectors, which, in Kress and van Leeuwen’s Reading Images (2006), plays a crucial role in distinguishing between ‘narrative’, action-oriented processes and ‘conceptual’, state-oriented processes. The use of this concept in image analysis has usually focused...... on the most salient vectors, and this works well, but many images contain a plethora of vectors, which makes their structure quite different from the linguistic transitivity structures with which Kress and van Leeuwen have compared ‘narrative’ images. It can also be asked whether facial expression vectors...... should be taken into account in discussing ‘reactions’, which Kress and van Leeuwen link only to eyeline vectors. Finally, the question can be raised as to whether actions are always realized by vectors. Drawing on a re-reading of Rudolf Arnheim’s account of vectors, these issues are outlined...

  20. A Transverse Oscillation Approach for Estimation of Three-Dimensional Velocity Vectors, Part II: Experimental Validation

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev

    2014-01-01

    The 3-D transverse oscillation method is investigated by estimating 3-D velocities in an experimental flowrigsystem. Measurements of the synthesized transverse oscillatingfields are presented as well. The method employs a 2-D transducer; decouples the velocity estimation; and estimates the axial,...

  1. Determination of velocity vector angles using the directional cross-correlation method

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt

    2005-01-01

    A method for determining both velocity magnitude and angle in any direction is suggested. The method uses focusing along the velocity direction and cross-correlation for finding the correct velocity magnitude. The angle is found from beamforming directional signals in a number of directions...... and then select the angle with the highest normalized correlation between directional signals. The approach is investigated using Field II simulations and data from the experimental ultrasound scanner RASMUS and with a parabolic flow having a peak velocity of 0.3 m/s. A 7 MHz linear array transducer is used...... with a normal transmission of a focused ultrasound field. The velocity profile estimates from simulations have relative mean standard deviations between 0 . 7% and 7 . 7% for flow between 45 ◦ and 90 ◦ . The angle estimation performance is highly dependent on the choice of the time k tprf · T prf ( correlation...

  2. Generation of iPS Cells from Human Peripheral Blood Mononuclear Cells Using Episomal Vectors.

    Science.gov (United States)

    Su, Ruijun Jeanna; Neises, Amanda; Zhang, Xiao-Bing

    2016-01-01

    Peripheral blood is the easy-to-access, minimally invasive, and the most abundant cell source to use for cell reprogramming. The episomal vector is among the best approaches for generating integration-free induced pluripotent stem (iPS) cells due to its simplicity and affordability. Here we describe the detailed protocol for the efficient generation of integration-free iPS cells from peripheral blood mononuclear cells. With this optimized protocol, one can readily generate hundreds of iPS cell colonies from 1 ml of peripheral blood.

  3. Effect of head rotation on cerebral blood velocity in the prone position

    DEFF Research Database (Denmark)

    Højlund, Jakob; Sandmand, Marie; Sonne, Morten;

    2012-01-01

    for cerebral blood flow. We tested in healthy subjects the hypothesis that rotating the head in the prone position reduces cerebral blood flow. Methods. Mean arterial blood pressure (MAP), stroke volume (SV), and CO were determined, together with the middle cerebral artery mean blood velocity (MCA V......(mean)) and jugular vein diameters bilaterally in 22 healthy subjects in the prone position with the head centered, respectively, rotated sideways, with and without positive pressure breathing (10 cmH(2)O). Results. The prone position reduced SV (by 5.4 ± 1.5%; P ...(mean) was maintained. The head-rotated prone position with positive pressure breathing augmented MAP further (87 ± 2 mmHg) but not CO, narrowed both jugular vein diameters, and reduced MCA V(mean) (by 8.6 ± 3.2 %). Conclusion. During positive pressure breathing the prone position with sideways rotated head reduces MCA...

  4. Force, velocity, and work: The effects of different contexts on students' understanding of vector concepts using isomorphic problems

    Science.gov (United States)

    Barniol, Pablo; Zavala, Genaro

    2014-12-01

    In this article we compare students' understanding of vector concepts in problems with no physical context, and with three mechanics contexts: force, velocity, and work. Based on our "Test of Understanding of Vectors," a multiple-choice test presented elsewhere, we designed two isomorphic shorter versions of 12 items each: a test with no physical context, and a test with mechanics contexts. For this study, we administered the items twice to students who were finishing an introductory mechanics course at a large private university in Mexico. The first time, we administered the two 12-item tests to 608 students. In the second, we only tested the items for which we had found differences in students' performances that were difficult to explain, and in this case, we asked them to show their reasoning in written form. In the first administration, we detected no significant difference between the medians obtained in the tests; however, we did identify significant differences in some of the items. For each item we analyze the type of difference found between the tests in the selection of the correct answer, the most common error on each of the tests, and the differences in the selection of incorrect answers. We also investigate the causes of the different context effects. Based on these analyses, we establish specific recommendations for the instruction of vector concepts in an introductory mechanics course. In the Supplemental Material we include both tests for other researchers studying vector learning, and for physics teachers who teach this material.

  5. Fiber-Based Doppler Lidar for Vector Velocity and Altitude Measurements

    Science.gov (United States)

    Amzajerdian, Farzin; Pierrottet, Diego; Hines, Glenn; Petway, Larry; Barnes, Bruce

    2015-01-01

    A coherent Doppler lidar capable of providing accurate velocity and altitude data has been developed and demonstrated for future NASA missions to the solar system bodies requiring precision navigation and controlled soft landing.

  6. Measuring two-dimensional components of a flow velocity vector using a hot-wire probe.

    Science.gov (United States)

    Kiełbasa, Jan

    2007-08-01

    The article presents a single-hot-wire probe adapted to detect the direction of flow velocity. The modification consists of the introduction of a third support which allows to measure voltage at the central point of the wire. The sign of voltage difference DeltaU between both parts of the wire is the measure of the direction of flow velocity in a system of coordinates associated with the probe.

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

    Science.gov (United States)

    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.

  8. Voluntary respiratory control and cerebral blood flow velocity upon ice-water immersion

    DEFF Research Database (Denmark)

    Mantoni, Teit; Rasmussen, Jakob Højlund; Belhage, Bo;

    2008-01-01

    INTRODUCTION: In non-habituated subjects, cold-shock response to cold-water immersion causes rapid reduction in cerebral blood flow velocity (approximately 50%) due to hyperventilation, increasing risk of syncope, aspiration, and drowning. Adaptation to the response is possible, but requires...... several cold immersions. This study examines whether thorough instruction enables non-habituated persons to attenuate the ventilatory component of cold-shock response. METHODS: There were nine volunteers (four women) who were lowered into a 0 degrees C immersion tank for 60 s. Middle cerebral artery mean......: Even without prior cold-water experience, subjects were able to suppress reflex hyperventilation following ice-water immersion, maintaining the cerebral blood flow velocity at a level not associated with impaired consciousness. This study implies that those susceptible to accidental cold...

  9. Comparison of Real-Time In Vivo Spectral and Vector Velocity Estimation

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per;

    2012-01-01

    The purpose of this study is to show whether a newly introduced vector flow method is equal to conventional spectral estimation. Thirty-two common carotid arteries of 16 healthy volunteers were scanned using a BK Medical ProFocus scanner (DK-2730, Herlev, Denmark) and a linear transducer at 5 MHz...

  10. Convex Array Vector Velocity Imaging Using Transverse Oscillation and Its Optimization

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Brandt, Andreas Hjelm; Bachmann Nielsen, Michael

    2015-01-01

    A method for obtaining vector flow images using the transverse oscillation (TO) approach on a convex array is presented. The paper presents optimization schemes for TO fields and evaluates their performance using simulations and measurements with an experimental scanner. A 3-MHz 192-element conve...

  11. On Ultrasonic MTI Measurement of Velocity Profiles in Blood-Flow

    Directory of Open Access Journals (Sweden)

    Bjørn A.J. Angelsen

    1981-04-01

    Full Text Available A theoretical analysis of Doppler frequency estimators proposed to be used in ultrasonic MTI measurements of velocity profiles in blood flow, is given. The estimators give an output in form of a single analogue voltage and the relation of the output to the Doppler spectrum is discussed. Three new estimators are also proposed. All estimators work fairly well for narrow-band Doppler spectra, but errors are found when broad-band spectra are present.

  12. Voluntary respiratory control and cerebral blood flow velocity upon ice-water immersion

    DEFF Research Database (Denmark)

    Mantoni, Teit; Rasmussen, Jakob Højlund; Belhage, Bo;

    2008-01-01

    In non-habituated subjects, cold-shock response to cold-water immersion causes rapid reduction in cerebral blood flow velocity (approximately 50%) due to hyperventilation, increasing risk of syncope, aspiration, and drowning. Adaptation to the response is possible, but requires several cold...... immersions. This study examines whether thorough instruction enables non-habituated persons to attenuate the ventilatory component of cold-shock response....

  13. The residual velocity method applied to a steady free boundary-value problem of vector Laplacian type

    Science.gov (United States)

    Chen, Wan; Wetton, Brian

    2009-02-01

    We consider a free boundary-value problem based on a simplified model of two-phase flow in porous media. The model has two independent variables on each side of the free interface. At the interface at steady state, five mixed Dirichlet and Neumann conditions are given. The movement of the interface in time-dependent situations can be reduced to a normal motion proportional to the residual in one of the steady-state interface conditions (the elliptic interior problems and the other interface conditions are satisfied at each time). Following previous work, we consider the use of other residuals for the normal velocity that have superior numerical properties. The well-posedness criteria for this vector example are particularly clear. The advantages of the correctly chosen, non-physical residual velocities are demonstrated in numerical computations. Although the finite-difference implementation in this work is not applicable to general problems, it has superior performance to previous implementations.

  14. Rizatriptan does not change cerebral blood flow velocity during migraine attacks.

    Science.gov (United States)

    Gori, S; Morelli, N; Bellini, G; Bonanni, E; Manca, L; Orlandi, G; Iudice, A; Murri, L

    2005-04-30

    Rizatriptan represents a major advance in the treatment of migraine attack: inhibition of peripheral trigeminal nerve and constriction of intracranial extracerebral blood vessels have been proposed as its main antimigraine mechanisms of action. Although many studies may suggest that rizatriptan causes highly selective vasoconstriction within intracranial extracerebral vessels (i.e., meningeal arteries), no literature data are available to date on possible cerebral hemodynamic changes in humans after treatment with rizatriptan. The aim of this study was to evaluate the effect of rizatriptan on cerebral blood flow velocity performing transcranial Doppler during spontaneous attacks of migraine without aura. Fourteen patients suffering from migraine without aura were monitored to evaluate mean flow velocity changes on both middle cerebral arteries during migraine attack 30 min before and 120 min after oral administration of rizatriptan 10mg. Monitoring was repeated for 30 min during the pain-free period. All patients turned out to be drug responders and no significant mean flow velocity changes were observed between the pain-free period and pre-treatment phase; besides no significant difference in mean flow velocity value have been detected between the periods after the drug administration during the attack versus both pre-treatment period and pain-free phase. These findings indicate that the antimigraine action of rizatriptan is not associated with clear intracranial cerebral hemodynamic changes and may support its cerebrovascular safety.

  15. Blood flow velocity in the popliteal vein using transverse oscillation ultrasound

    Science.gov (United States)

    Bechsgaard, Thor; Hansen, Kristoffer Lindskov; Brandt, Andreas Hjelm; Holbek, Simon; Lönn, Lars; Strandberg, Charlotte; Bækgaard, Niels; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

    2016-04-01

    Chronic venous disease is a common condition leading to varicose veins, leg edema, post-thrombotic syndrome and venous ulcerations. Ultrasound (US) is the main modality for examination of venous disease. Color Doppler and occasionally spectral Doppler US (SDUS) are used for evaluation of the venous flow. Peak velocities measured by SDUS are rarely used in a clinical setting for evaluating chronic venous disease due to inadequate reproducibility mainly caused by the angle dependency of the estimate. However, estimations of blood velocities are of importance in characterizing venous disease. Transverse Oscillation US (TOUS), a non-invasive angle independent method, has been implemented on a commercial scanner. TOUS's advantage compared to SDUS is a more elaborate visualization of complex flow. The aim of this study was to evaluate, whether TOUS perform equal to SDUS for recording velocities in the veins of the lower limbs. Four volunteers were recruited for the study. A standardized flow was provoked with a cuff compression-decompression system placed around the lower leg. The average peak velocity in the popliteal vein of the four volunteers was 151.5 cm/s for SDUS and 105.9 cm/s for TOUS (p measures for the evaluation of venous blood flow.

  16. Effect of Electrical Stimulation on Blood Flow Velocity and Vessel Size

    Science.gov (United States)

    Jin, Hee-Kyung; Hwang, Tae-Yeon; Cho, Sung-Hyoun

    2017-01-01

    Abstract Interferential current electrical stimulation alters blood flow velocity and vessel size. We aimed to investigate the changes in the autonomic nervous system depending on electrical stimulation parameters. Forty-five healthy adult male and female subjects were studied. Bipolar adhesive pad electrodes were used to stimulate the autonomic nervous system at the thoracic vertebrae 1-4 levels for 20 min. Using Doppler ultrasonography, blood flow was measured to determine velocity and vessel size before, immediately after, and 30 min after electrical stimulation. Changes in blood flow velocity were significantly different immediately and 30 min after stimulation. The interaction between intervention periods and groups was significantly different between the exercise and pain stimulation groups immediately after stimulation (p<0.05). The vessel size was significantly different before and 30 min after stimulation (p<0.05). Imbalances in the sympathetic nervous system, which regulates balance throughout the body, may present with various symptoms. Therefore, in the clinical practice, the parameters of electrical stimulation should be selectively applied in accordance with various conditions and changes in form.

  17. Clinical Study of the Ascending Aorta Wall Motion by Velocity Vector Imaging in Patients with Primary Hypertension

    Institute of Scientific and Technical Information of China (English)

    Lei WANG; Jing WANG; Mingxing XIE; Xinfang WANG; Qing LV; Ming CHEN; Shaoping ZHENG

    2009-01-01

    We studied the wall motion characteristics of the ascending aorta by velocity vector im-aging (VVI) in primary hypertension patients.The ascending aortas both in 30 patients with primary hypertension and 30 normal controls were examined by Acuson sequoia 512 equiped with VVI.The maximum velocity (Vs,Ve) of every point on the anterior wall of ascending aorta both in systole and diastole was measured.The aortic diameter was wider in the hypertension patients than that in the healthy subjects (P0.05).The velocity curves of the anterior wall of ascending aorta both in the hypertension and healthy subjects were regular,and the curve in systole was named S wave and that in diastole named E wave.The velocity of S wave and E wave was slower in the hypertension pa-tients than that in the healthy subjects (P<0.05).The time to peak of S wave on the anterior wall of ascending aorta in systole was shorter in the hypertension patients than in the healthy subjects (P<0.05).VVI could be used to accurately and directly observe the movement character of the as-cending aorta walls,which would help us understand the elasticity of great arteries in patients with hypertension.

  18. In Vivo Three-Dimensional Velocity Vector Imaging and Volumetric Flow Rate Measurements

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev;

    2013-01-01

    scanner SARUS. Measurements are conducted on a carotid artery flow phantom from Danish Phantom Design, and 20 frames are acquired with a constant flow rate of 16.7±0.17 mL/s provided by a Shelley Medical Imaging Technologies CompuFlow 1000 system. The peak velocity magnitude in the vessel is found......-mode velocities is conducted over five heart beats. The peak systolic and end-diastolic velocities are 69±5.4 cm/s and 7.9±5.5 cm/s at the center of the vessel. For comparison, a commercial BK Medical ultrasound scanner using the spectral estimator yields 71.2 cm/s and 7.70 cm/s, respectively. The results...

  19. Intrauterine growth restriction, visceral blood flow velocity and exocrine pancreatic function

    Directory of Open Access Journals (Sweden)

    Deenmamode Jean M

    2008-11-01

    Full Text Available Abstract Background Animal models and observations in human neonates suggest fetal exocrine pancreas vulnerability to reduced maternofetal blood flow. We investigated the relationship between superior mesenteric artery blood flow velocity (sma bfv and exocrine pancreatic function, in a cohort of very low birth weight (VLBW babies. Group 1: 9 babies Group2: 18 babies > 10th percentile for birth weight. Findings All had Doppler ultrasound scan of the superior mesenteric artery (sma, by same operator (RMN, on day 1 of life before commencement of enteral feeding. Stool samples assayed for faecal chymotrypsin and weekly serum samples assayed for amylase and lipase (kinetic colorimetric assay from days 1 to 14 of life. Growth restricted babies had significantly lower sma bfv values compared with appropriately grown preterm babies. Faecal chymotrypsin levels were also lower but this difference did not achieve statistical significance. Both groups had serum lipase levels detectable in adult concentrations. Serum amylase was undetectable in either group. Conclusion Babies with previous in-utero blood flow redistribution may exhibit altered gut ontogeny with re-setting of mesenteric blood flow velocities and altered exocrine pancreatic function.

  20. Velocity vector estimation in synthetic aperture flow and B-mode imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2004-01-01

    normalized correlation calculated as a function of angle. The method is investigated using data measured by an experimental ultrasound scanner from a flow rig. A commercial 7 MHz linear array transducer is used and data are measured for flow angles of 60° and 90°. The velocity magnitude is determined...

  1. Optimal velocity encoding during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography

    Institute of Scientific and Technical Information of China (English)

    Gang Guo; Yonggui Yang; Weiqun Yang

    2011-01-01

    This study investigated the effect of velocity encoding on measurement of brain blood flow and blood volume of inflow and outflow using phase-contrast magnetic resonance angiography. A single two-dimensional phase-contrast magnetic resonance angiography slice was applied perpendicular to the internal carotid artery and the vertebral artery at C2 level. For each subject, the velocity encoding was set from 30 to 90 cm/s with an interval of 10 cm/s for a total of seven settings. Various velocity encodings greatly affected blood flow volume, maximal blood flow velocity and mean blood flow velocity in the internal carotid artery, but did not significantly affect vertebral arteries and jugular veins. When velocity encoding was 60-80 cm/s, the inflow blood volume was 655 ± 118 mL/min, and the outflow volume was 506 ± 186 mL/min. The ratio of outflow/inflow was steady at 0.78-0.83, and there was no aliasing in any of the images. These findings suggest that velocity encodings of 60-80 cm/s should be selected during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography.

  2. Vector blood meals are an early indicator of the effectiveness of the Ecohealth approach in halting Chagas transmission in Guatemala.

    Science.gov (United States)

    Pellecer, Mariele J; Dorn, Patricia L; Bustamante, Dulce M; Rodas, Antonieta; Monroy, M Carlota

    2013-04-01

    A novel method using vector blood meal sources to assess the impact of control efforts on the risk of transmission of Chagas disease was tested in the village of El Tule, Jutiapa, Guatemala. Control used Ecohealth interventions, where villagers ameliorated the factors identified as most important for transmission. First, after an initial insecticide application, house walls were plastered. Later, bedroom floors were improved and domestic animals were moved outdoors. Only vector blood meal sources revealed the success of the first interventions: human blood meals declined from 38% to 3% after insecticide application and wall plastering. Following all interventions both vector blood meal sources and entomological indices revealed the reduction in transmission risk. These results indicate that vector blood meals may reveal effects of control efforts early on, effects that may not be apparent using traditional entomological indices, and provide further support for the Ecohealth approach to Chagas control in Guatemala.

  3. The impact of contralateral cooling on skin capillary blood cell velocity in patients with diabetes mellitus.

    Science.gov (United States)

    Haak, E; Haak, T; Grözinger, Y; Krebs, G; Usadel, K H; Kusterer, K

    1998-01-01

    In healthy volunteers, cooling of the contralateral hand leads to a rapid decrease in the ipsilateral capillary perfusion via a nerval reflex arc. The aim of this study was to investigate whether this reflex arc after contralateral cooling might be altered in patients with diabetes mellitus with and without peripheral neuropathy. Therefore, 12 patients with diabetic neuropathy (4 IDDM, diabetes duration 17.2 +/- 2.9 (SD) years, age 60.8 +/- 4.0 years, HbA1c 6.5 +/- 0.3%) and 12 patients with diabetes mellitus but without neuropathy (6 IDDM, diabetes duration 15.1 +/- 2.7 years, age 55.9 +/- 4.5 years, HbA1c 5.4 +/- 0.1%) were investigated by nailfold capillaroscopy. Twelve healthy volunteers (age 56.8 +/- 3.1 years, HbA1c 4.8 +/- 0.2%) served as controls. Contralateral skin capillary blood cell velocity was determined at rest and during the following 20 min after cooling of the hand (3 min at 15 degreesC). Blood pressure, heart rate and local skin temperature were examined regularly during the investigation. Resting capillary blood cell velocity did not differ between patients and controls. While contralateral cooling resulted in a decrease in capillary blood cell velocity (CBV) in controls (0.29 +/- 0.05 vs. 0.42 +/- 0.05 mm/s, p nerval reflex arcs are impaired. A long-term follow-up in a larger number of patients is required to evaluate whether these findings might serve as a very early diagnostic tool for the diagnosis of developing diabetic neuropathy.

  4. Vector velocity volume flow estimation: Sources of error and corrections applied for arteriovenous fistulas

    DEFF Research Database (Denmark)

    Jensen, Jonas; Olesen, Jacob Bjerring; Stuart, Matthias Bo;

    2016-01-01

    radius. The error sources were also studied in vivo under realistic clinical conditions, and the theoretical results were applied for correcting the volume flow errors. Twenty dialysis patients with arteriovenous fistulas were scanned to obtain vector flow maps of fistulas. When fitting an ellipsis...... to cross-sectional scans of the fistulas, the major axis was on average 10.2 mm, which is 8.6% larger than the minor axis. The ultrasound beam was on average 1.5 mm from the vessel center, corresponding to 28% of the semi-major axis in an average fistula. Estimating volume flow with an elliptical, rather...

  5. A method for real-time three-dimensional vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav

    2003-01-01

    . Parabolic flow in a 10 mm radius vessel inclined at 60 degrees to the acoustical axis of the transducer was simulated. The mean standard deviation of he estimates was 0.0098 m/s over the whole vessel cross-section, which is 3.3% relative to the peak velocity. The bias was 0.023 m/s (7.5%). False peaks were...

  6. The effect of nitrous oxide on cerebral blood flow velocity in children anaesthetised with sevoflurane.

    Science.gov (United States)

    Rowney, D A; Fairgrieve, R; Bissonnette, B

    2004-01-01

    To determine the effects of nitrous oxide on middle cerebral artery blood flow velocity (CBFV) during sevoflurane anaesthesia in children, CBFV was measured using transcranial Doppler sonography in 16 ASA I or II children. Anaesthesia consisted of 1.0 MAC sevoflurane in 30% oxygen with intermittent positive pressure ventilation maintaining FEco2 at 38 mmHg (5.0 kPa) and a caudal epidural block using 0.25% bupivacaine 1.0 ml.kg-1. The remainder of the inspired gas was varied in one of two sequences either air/nitrous oxide/air or nitrous oxide/air/nitrous oxide. The results showed that CBFV decreased when nitrous oxide was replaced by air (p = 0.03) and returned to its initial value when nitrous oxide was reintroduced. CBFV increased when air was replaced by nitrous oxide (p = 0.04) and returned to its initial value when air was reintroduced. Mean heart rate and blood pressure remained constant. We conclude that nitrous oxide increases cerebral blood flow velocity in healthy children anaesthetised with 1.0 MAC sevoflurane.

  7. Implementation of ultrasound time-domain cross-correlation blood velocity estimators

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1993-01-01

    are used in the algorithm, imposing a heavy burden on the signal processing hardware. The algorithm is analyzed with regard to the high sampling frequency, and a method for performing real-time high-speed-movement and cross-correlation is suggested. Implementation schemes based on using the sign......The implementation of real-time blood velocity estimators using time-domain cross-correlation is investigated. The basic algorithm for stationary echo canceling, cross-correlation estimation and subsequent velocity estimation is presented. Sampled data acquired at rates of approximately 20 MHz...... of the data as well as the full precision are proposed. From an analysis of the process it is concluded that the sign data implementation can attain real-time processing. This can also be obtained for the full precision data, but at the expense of using a number of dedicated signal processing chips. Both...

  8. Retinal hemodynamic oxygen reactivity assessed by perfusion velocity, blood oximetry and vessel diameter measurements

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Lauritsen, Anne Øberg; Larsen, Michael

    2015-01-01

    PURPOSE: To test the oxygen reactivity of a fundus photographic method of measuring macular perfusion velocity and to integrate macular perfusion velocities with measurements of retinal vessel diameters and blood oxygen saturation. METHODS: Sixteen eyes in 16 healthy volunteers were studied at two...... examination sessions using motion-contrast velocimetry and retinal oximetry with vessel diameter corrections. To test oxygen reactivity, participants were examined during normoxia, after 15 min of hyperoxia and finally after 45 min of normoxia. Repeatability was assessed by intraclass correlation coefficients...... retinal arterial oxygen saturation from 95.1 ± 5.0% to 96.6 ± 6.4% (p = 0.038) and increased retinal venous oxygen saturation from 62.9 ± 6.7% to 70.3 ± 7.8% (p = 0.0010). Parameters returned to baseline levels after subsequent normoxia. Saturation and vessel diameter ICCs were 0.88-0.98 (range...

  9. A velocity tracking approach for the data assimilation problem in blood flow simulations.

    Science.gov (United States)

    Tiago, J; Guerra, T; Sequeira, A

    2016-11-24

    Several advances have been made in data assimilation techniques applied to blood flow modeling. Typically, idealized boundary conditions, only verified in straight parts of the vessel, are assumed. We present a general approach, on the basis of a Dirichlet boundary control problem, that may potentially be used in different parts of the arterial system. The relevance of this method appears when computational reconstructions of the 3D domains, prone to be considered sufficiently extended, are either not possible, or desirable, because of computational costs. On the basis of taking a fully unknown velocity profile as the control, the approach uses a discretize then optimize methodology to solve the control problem numerically. The methodology is applied to a realistic 3D geometry representing a brain aneurysm. The results show that this data assimilation approach may be preferable to a pressure control strategy and that it can significantly improve the accuracy associated to typical solutions obtained using idealized velocity profiles.

  10. Performance of velocity vector estimation using an improved dynamic beamforming setup

    DEFF Research Database (Denmark)

    Munk, Peter; Jensen, Jørgen Arendt

    2001-01-01

    control of the acoustic field, based on the Pulsed Plane Wave Decomposition (PPWD), is presented. The PPWD gives an unambigious relation between a given acoustic field and the time functions needed on an array transducer for transmission. Applying this method for the receive beamformation results in a set......-up of the beamformer with different filters for each channel for each estimation depth. The method of the PPWD is illustrated by analytical expressions of the decomposed acoustic field and these results are used for simulation. Results of velocity estimates using the new setup are given on the basis of simulated...

  11. Optimization of Transverse Oscillating Fields for Vector Velocity Estimation with Convex Arrays

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2013-01-01

    A method for making Vector Flow Images using the transverse oscillation (TO) approach on a convex array is presented. The paper presents optimization schemes for TO fields for convex probes and evaluates their performance using Field II simulations and measurements using the SARUS experimental......;1. lx is maintained between 1.47 and 1.70 mm from 25 mm to 70 mm and is increased to 2.8 mm at a depth of 100 mm. Parabolic profiles are estimated using 16 missions. The optimization gives a reduction in std. from 8.5% to 5.9% with a reduction in bias from 35% to 1.02% at 90 degrees (transverse flow...

  12. Effect of labetalol on cerebral blood flow and middle cerebral arterial flow velocity in healthy volunteers

    DEFF Research Database (Denmark)

    Schroeder, T; Schierbeck, Jens; Howardy, P;

    1991-01-01

    in normotensive subjects. Neither does it affect CO2 reactivity. The uniform results obtained with the two methods suggest TCD as a usable alternative to conventional CBF technique in the assessment of cerebral vasoactivity of various drugs in subjects with a normal cerebral circulation.......The effect of labetalol, a combined alpha- and beta-adrenoceptor antagonist, on the cerebral circulation was investigated in 7 normotensive subjects. Cerebral blood flow (CBF) was measured with the intravenous 133Xe method and mean flow velocity (Vmean) in the middle cerebral artery was determined...

  13. Generation of human induced pluripotent stem cells from peripheral blood using the STEMCCA lentiviral vector.

    Science.gov (United States)

    Sommer, Andreia Gianotti; Rozelle, Sarah S; Sullivan, Spencer; Mills, Jason A; Park, Seon-Mi; Smith, Brenden W; Iyer, Amulya M; French, Deborah L; Kotton, Darrell N; Gadue, Paul; Murphy, George J; Mostoslavsky, Gustavo

    2012-10-31

    Through the ectopic expression of four transcription factors, Oct4, Klf4, Sox2 and cMyc, human somatic cells can be converted to a pluripotent state, generating so-called induced pluripotent stem cells (iPSCs)(1-4). Patient-specific iPSCs lack the ethical concerns that surround embryonic stem cells (ESCs) and would bypass possible immune rejection. Thus, iPSCs have attracted considerable attention for disease modeling studies, the screening of pharmacological compounds, and regenerative therapies(5). We have shown the generation of transgene-free human iPSCs from patients with different lung diseases using a single excisable polycistronic lentiviral Stem Cell Cassette (STEMCCA) encoding the Yamanaka factors(6). These iPSC lines were generated from skin fibroblasts, the most common cell type used for reprogramming. Normally, obtaining fibroblasts requires a skin punch biopsy followed by expansion of the cells in culture for a few passages. Importantly, a number of groups have reported the reprogramming of human peripheral blood cells into iPSCs(7-9). In one study, a Tet inducible version of the STEMCCA vector was employed(9), which required the blood cells to be simultaneously infected with a constitutively active lentivirus encoding the reverse tetracycline transactivator. In contrast to fibroblasts, peripheral blood cells can be collected via minimally invasive procedures, greatly reducing the discomfort and distress of the patient. A simple and effective protocol for reprogramming blood cells using a constitutive single excisable vector may accelerate the application of iPSC technology by making it accessible to a broader research community. Furthermore, reprogramming of peripheral blood cells allows for the generation of iPSCs from individuals in which skin biopsies should be avoided (i.e. aberrant scarring) or due to pre-existing disease conditions preventing access to punch biopsies. Here we demonstrate a protocol for the generation of human iPSCs from

  14. [Coronary artery blood flow velocity non-invasively measured using a vessel-tracking pulsed Doppler system].

    Science.gov (United States)

    Tateishi, O; Aizawa, O; Okamura, T; Yoshida, T; Furuhata, H; Seo, Y; Iinuma, K; Shiki, E

    1988-09-01

    A newly-developed noninvasive method was used to measure left coronary blood flow during phantom experiments. Two techniques were used in which: (1) the sample position can always be set in a fluctuating vessel using a wall echo-tracking method with a phase-locked-loop, and (2) the Doppler reference signal was generated separately synchronous with the wall echo signal. These techniques were combined, using a commercially available pulsed Doppler apparatus (SSH-40B: Toshiba). Basic experiments were performed using a blood vessel phantom to verify the validity of these systems. Blood flow velocity in the fluctuating tube could be measured clearly using a vessel-tracking method. The blood flow velocity of the left anterior descending artery was measured in three normal subjects and in seven patients from the third intercostal space along the left sternal border. The velocity pattern was characterized by a crescendo-decrescendo shape in diastole. The peak velocity which appeared in diastole ranged from 19 to 69 cm/sec, with no difference by disease entity. However, in all cases, the blood flow velocity signals were marred by extraneous signals, making it impossible to measure blood flow velocity during systole. Further improvement of the system is mandatory in order to use this flowmeter clinically.

  15. Effects of prostaglandin analogs on blood flow velocity and resistance in the ophthalmic artery of rabbits

    Directory of Open Access Journals (Sweden)

    Amália Turner Giannico

    2016-02-01

    Full Text Available ABSTRACT Purpose: The aim of this study was to investigate the effects of prostaglandin analogs on blood flow in the ophthalmic artery of clinically healthy rabbits. Methods: Fifty-five clinically healthy New Zealand white rabbits were divided into six groups, and the left eyes were treated for four weeks with the preservative benzalkonium chloride (BAK only or a topical formulation of different prostaglandin analogs (bimatoprost BAK, tafluprost BAK-free, travoprost BAK, travoprost POLYQUAD, and latanoprost BAK. Color Doppler imaging was performed before and after the treatments. The mean values of the peak systolic velocity (PSV and end diastolic velocity and the resistive index (RI were calculated. Statistical analysis was performed to compare the differences pre- and post-treatment for each drug and post-treatment among the drugs. Results: The prostaglandin analogs did not affect PSV. Bimatoprost BAK, travoprost POLYQUAD, and latanoprost BAK did not change RI. Tafluprost BAK-free and travoprost BAK therapy resulted in similar reductions in RI. No significant differences pre- and post-treatment were found when BAK was administered alone. Conclusion: The prostaglandin analogs tafluprost BAK-free and travoprost BAK improved blood flow in the ophthalmic artery in healthy New Zealand white rabbits, which suggests that these drugs enhance the prevention of the progression the progression of glaucoma.

  16. Izmerenie vektora skorosti lazernym dopplerovskim anemometrom (LDA s volokonno-opticheskimi traktami[Measurement of the velocity vector of the laser Doppler anemometer (LDA with fiber-optic tracts

    Directory of Open Access Journals (Sweden)

    S. N. Khotyaintsev

    1982-12-01

    Full Text Available The problems encountered in the development of laser Doppler velocity vector meter optical fiber paths. The scheme of the meter, including three-dimensional velocity meter made by differential circuit. Describes the experimental setup and the results of the experiment by measuring the two projections of the velocity vector.

  17. DIRDOP: a directivity approach to determining the seismic rupture velocity vector

    Science.gov (United States)

    Caldeira, Bento; Bezzeghoud, Mourad; Borges, José F.

    2010-07-01

    Directivity effects are a characteristic of seismic source finiteness and are a consequence of the rupture spread in preferential directions. These effects are manifested through seismic spectral deviations as a function of the observation location. The directivity by Doppler effect method permits estimation of the directions and rupture velocities, beginning from the duration of common pulses, which are identified in waveforms or relative source time functions. The general model of directivity that supports the method presented here is a Doppler analysis based on a kinematic source model of rupture (Haskell, Bull Seismol Soc Am 54:1811-1841, 1964) and a structural medium with spherical symmetry. To evaluate its performance, we subjected the method to a series of tests with synthetic data obtained from ten typical seismic ruptures. The experimental conditions studied correspond with scenarios of simple and complex, unilaterally and bilaterally extended ruptures with different mechanisms and datasets with different levels of azimuthal coverage. The obtained results generally agree with the expected values. We also present four real case studies, applying the method to the following earthquakes: Arequipa, Peru ( M w = 8.4, June 23, 2001); Denali, AK, USA ( M w = 7.8; November 3, 2002); Zemmouri-Boumerdes, Algeria ( M w = 6.8, May 21, 2003); and Sumatra, Indonesia ( M w = 9.3, December 26, 2004). The results obtained from the dataset of the four earthquakes agreed, in general, with the values presented by other authors using different methods and data.

  18. Fuzzy Velocity Biased-Ad Hoc on Demand Distance Vector to Improve Throughput in Dynamic Mobile Network

    Directory of Open Access Journals (Sweden)

    K. Tamizarasu

    2012-01-01

    Full Text Available Problem statement: With the escalating demand for mobile ad hoc network projects, major challenges to system planners and designers were addressing stability and reliability problems due to frequent change of network topology. Controlling an overhead, which means bandwidth utilization due to control packets, depends on the routing protocol, topology and data traffic. Limiting the network control overheads, of this highly dynamic and dense network to acceptable level, was closely linked to the function of increased link changes. The throughput of the network can be improved with dynamically limiting of the routing control overheads. Approach: We propose a improved AODV mechanism Fuzzy Velocity Biased-Adhoc on Demand Distance Vector (FVB-AODV which dynamically modifies the AODV control overhead parameters based on the relative velocity between two communicating nodes. Conclusion/Recommendation: The proposed algorithm is able to achieve its objectives by increasing the throughput at high node mobility. Dynamically modifying the overheads improved the bandwidth utilization. The additional overheads on the node CPU however needs to be evaluated.

  19. A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound

    Directory of Open Access Journals (Sweden)

    Jaeseong Jang

    2015-01-01

    Full Text Available Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance.

  20. In vivo validation of a blood vector velocity estimator with MR angiography

    DEFF Research Database (Denmark)

    Hansen, K.L.; Udesen, J.; Thomsen, C.;

    2009-01-01

    was approximately 90 degrees for TO measurements. The correlation between the stroke volume estimated by TO and MRA was 0.91 (p Altman plot was additionally constructed where the mean difference was 0.2 ml with limits of agreement at -1...

  1. In Vivo Validation of a Blood Vector Velocity Estimator with MR Angiography

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Thomsen, Carsten;

    2009-01-01

    ° for TO measurements. The correlation between the stroke volume estimated by TO and MRA was 0.91 (p Altman plot was additionally constructed where the mean difference was 0.2 ml with limits of agreement at −1.4 ml and 1.9 ml. The results...

  2. 3D vector flow imaging

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes

    The main purpose of this PhD project is to develop an ultrasonic method for 3D vector flow imaging. The motivation is to advance the field of velocity estimation in ultrasound, which plays an important role in the clinic. The velocity of blood has components in all three spatial dimensions, yet...... conventional methods can estimate only the axial component. Several approaches for 3D vector velocity estimation have been suggested, but none of these methods have so far produced convincing in vivo results nor have they been adopted by commercial manufacturers. The basis for this project is the Transverse...... on the TO fields are suggested. They can be used to optimize the TO method. In the third part, a TO method for 3D vector velocity estimation is proposed. It employs a 2D phased array transducer and decouples the velocity estimation into three velocity components, which are estimated simultaneously based on 5...

  3. Evaluation of the asynchronization and function of the left ventricle in patients with chronic pulmonary hypertension by velocity vector imaging

    Institute of Scientific and Technical Information of China (English)

    WANG Chao-hong; WANG Yue-heng; NIU Ning-ning; XIE Ying-xin; WANG Lin

    2013-01-01

    Background Pulmonary hypertension (PH) is a set of pathophysiological syndromes characterized by increased pulmonary artery pressure and pulmonary vascular resistance,resulting in increased right ventricular afterload.The left and right ventricles interact through hemodynamics.What impact will PH have on synchronization and function of the left ventricle (LV)? The aim of this study was to evaluate the synchronization of the left ventricular wall motion and left ventricular function in patients with varying degrees of PH using velocity vector imaging (Wl) technology.Methods Sixty patients with chronic PH served as the experimental group,and 20 healthy volunteers served as the control group.According to the different degrees of pulmonary artery systolic pressure,the experimental group was divided into three groups:mild,moderate,and severe PH groups.The time to peak systolic longitudinal velocity (Tvl),the peak systolic longitudinal velocity (Vsl),the peak diastolic longitudinal velocity (Vel),the peak systolic longitudinal strain (SI),and strain rate (SRI) in 18 segments were measured in each group.Results TvI in the control group and each group with PH was reduced from basal to apical segment,and in control group Tvl in various segments of the same wall and in different walls showed no significant difference (P >0.05).With increase in pulmonary artery pressure,Tvl values measured showed an increasing trend in groups with PH.In groups with PH,Vsl and Vel of each wall were reduced sequentially from basal to apical segments,showing gradient change; Vsl and Vel values measured showed a decreasing trend with increase in pulmonary artery pressure,in which the differences of Vel values measured in the control group and the mild PH group were statistically significant (P <0.01),and the differences between other groups were statistically significant (P <0.01).In groups with PH,SI and SRI in basal segment and the middle segment of each wall were decreased; the

  4. Effect of Head Rotation on Cerebral Blood Velocity in the Prone Position

    Science.gov (United States)

    Højlund, Jakob; Sandmand, Marie; Sonne, Morten; Mantoni, Teit; Jørgensen, Henrik L.; Belhage, Bo; van Lieshout, Johannes J.; Pott, Frank C.

    2012-01-01

    Background. The prone position is applied to facilitate surgery of the back and to improve oxygenation in the respirator-treated patient. In particular, with positive pressure ventilation the prone position reduces venous return to the heart and in turn cardiac output (CO) with consequences for cerebral blood flow. We tested in healthy subjects the hypothesis that rotating the head in the prone position reduces cerebral blood flow. Methods. Mean arterial blood pressure (MAP), stroke volume (SV), and CO were determined, together with the middle cerebral artery mean blood velocity (MCA Vmean) and jugular vein diameters bilaterally in 22 healthy subjects in the prone position with the head centered, respectively, rotated sideways, with and without positive pressure breathing (10 cmH2O). Results. The prone position reduced SV (by 5.4 ± 1.5%; P < 0.05) and CO (by 2.3 ± 1.9 %), and slightly increased MAP (from 78 ± 3 to 80 ± 2 mmHg) as well as bilateral jugular vein diameters, leaving MCA Vmean unchanged. Positive pressure breathing in the prone position increased MAP (by 3.6 ± 0.8 mmHg) but further reduced SV and CO (by 9.3 ± 1.3 % and 7.2 ± 2.4 % below baseline) while MCA Vmean was maintained. The head-rotated prone position with positive pressure breathing augmented MAP further (87 ± 2 mmHg) but not CO, narrowed both jugular vein diameters, and reduced MCA Vmean (by 8.6 ± 3.2 %). Conclusion. During positive pressure breathing the prone position with sideways rotated head reduces MCA Vmean ~10% in spite of an elevated MAP. Prone positioning with rotated head affects both CBF and cerebrovenous drainage indicating that optimal brain perfusion requires head centering. PMID:22988456

  5. Transgenic quail production by microinjection of lentiviral vector into the early embryo blood vessels.

    Directory of Open Access Journals (Sweden)

    Zifu Zhang

    Full Text Available Several strategies have been used to generate transgenic birds. The most successful method so far has been the injection of lentiviral vectors into the subgerminal cavity of a newly laid egg. We report here a new, easy and effective way to produce transgenic quails through direct injection of a lentiviral vector, containing an enhanced-green fluorescent protein (eGFP transgene, into the blood vessels of quail embryos at Hamburger-Hamilton stage 13-15 (HH13-15. A total of 80 embryos were injected and 48 G0 chimeras (60% were hatched. Most injected embryo organs and tissues of hatched quails were positive for eGFP. In five out of 21 mature G0 male quails, the semen was eGFP-positive, as detected by polymerase chain reaction (PCR, indicating transgenic germ line chimeras. Testcross and genetic analyses revealed that the G0 quail produced transgenic G1 offspring; of 46 G1 hatchlings, 6 were transgenic (6/46, 13.0%. We also compared this new method with the conventional transgenesis using stage X subgerminal cavity injection. Total 240 quail embryos were injected by subgerminal cavity injection, of which 34 (14.1% were hatched, significantly lower than the new method. From these hatched quails semen samples were collected from 19 sexually matured males and tested for the transgene by PCR. The transgene was present in three G0 male quails and only 4/236 G1 offspring (1.7% were transgenic. In conclusion, we developed a novel bird transgenic method by injection of lentiviral vector into embryonic blood vessel at HH 13-15 stage, which result in significant higher transgenic efficiency than the conventional subgerminal cavity injection.

  6. Transgenic quail production by microinjection of lentiviral vector into the early embryo blood vessels.

    Science.gov (United States)

    Zhang, Zifu; Sun, Peng; Yu, Fuxian; Yan, Li; Yuan, Fang; Zhang, Wenxin; Wang, Tao; Wan, Zhiyi; Shao, Qiang; Li, Zandong

    2012-01-01

    Several strategies have been used to generate transgenic birds. The most successful method so far has been the injection of lentiviral vectors into the subgerminal cavity of a newly laid egg. We report here a new, easy and effective way to produce transgenic quails through direct injection of a lentiviral vector, containing an enhanced-green fluorescent protein (eGFP) transgene, into the blood vessels of quail embryos at Hamburger-Hamilton stage 13-15 (HH13-15). A total of 80 embryos were injected and 48 G0 chimeras (60%) were hatched. Most injected embryo organs and tissues of hatched quails were positive for eGFP. In five out of 21 mature G0 male quails, the semen was eGFP-positive, as detected by polymerase chain reaction (PCR), indicating transgenic germ line chimeras. Testcross and genetic analyses revealed that the G0 quail produced transgenic G1 offspring; of 46 G1 hatchlings, 6 were transgenic (6/46, 13.0%). We also compared this new method with the conventional transgenesis using stage X subgerminal cavity injection. Total 240 quail embryos were injected by subgerminal cavity injection, of which 34 (14.1%) were hatched, significantly lower than the new method. From these hatched quails semen samples were collected from 19 sexually matured males and tested for the transgene by PCR. The transgene was present in three G0 male quails and only 4/236 G1 offspring (1.7%) were transgenic. In conclusion, we developed a novel bird transgenic method by injection of lentiviral vector into embryonic blood vessel at HH 13-15 stage, which result in significant higher transgenic efficiency than the conventional subgerminal cavity injection.

  7. Cerebral blood flow velocities are reduced during attacks of unilateral migraine without aura

    DEFF Research Database (Denmark)

    Thomsen, L L; Iversen, Helle Klingenberg; Olesen, J

    1995-01-01

    aura in 25 patients. Blood velocity in the middle cerebral artery was lower on the headache side (59 cm/s) than on the non-headache side (65 cm/s) during the migraine attack. No such difference was found outside of attack (65 cm/s both sides). The difference (headache side minus non-headache side......) was on average -6.1 cm/s during attack compared to -0.4 cm/s outside of attack (p = 0.01). Assuming that rCBF is unchanged during attacks of migraine without aura, our results suggest a 9% increase in middle cerebral artery lumen (cross-sectional area) on the affected side during unilateral attacks of migraine...... without aura. The findings, however, do not necessarily mean that arterial dilatation is the only or even the most significant cause of pain....

  8. Changes in mean cerebral blood flow velocity during cognitive task-induced cerebral fatigue in high performance fighter pilots

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Chen

    2008-01-01

    BACKGROUND: Several studies have demonstrated that sustained cognitive tasks can induce cognitive fatigue and that the mean cerebral blood flow velocity changes in some cerebral regions during cerebral fatigue. OBJECTIVE: To dynamically monitor the changes in mean cerebral blood flow velocity in different brain regions of high performance fighter pilots during mental arithmetic tasks and consecutive performance tasks. DESIGN, TIME AND SETTING: The present neurophysiological trial, based on controlled observation, was performed at the Laboratory of Neurophysiology, Institute of Aviation Medicine, Air Force of China between January 2003 and December 2005. PARTICIPANTS: Forty-five males, high performance fighter pilots, averaging (27.6 ± 2.5) years, were recruited for this study. METHODS: The mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery of subjects was dynamically tested using transcranial Doppler during 5- hour mental arithmetic tasks and during 5- hour consecutive performance tasks. The neurobehavioral ability index was analyzed throughout each trial according to the number of correct responses, false responses, and lost responses. Simultaneously, cerebral cognitive fatigue-induced lethargy was assessed by the Stanford Sleepiness Scale. MAIN OUTCOME MEASURES: Changes in mean cerebral blood flow velocity in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery; neurobehavioral ability index of mental arithmetic and consecutive performance tasks; Stanford Sleepiness Scale scores. RESULTS: During mental arithmetic tasks, the mean cerebral blood flow velocity in the anterior cerebral artery increased during hour 2 and decreased after hour 4. There was no significant change in mean cerebral blood flow velocity in the middle cerebral artery and posterior cerebral artery. During hour 4, cerebral cognitive fatigue was observed and, simultaneously, Stanford Sleepiness

  9. Training-induced changes on blood lactate profile and critical velocity in young swimmers.

    Science.gov (United States)

    Toubekis, Argyris G; Tsami, Aikaterini P; Smilios, Ilias G; Douda, Helen T; Tokmakidis, Savvas P

    2011-06-01

    This study examines the efficacy of critical swimming velocity (CV) for training prescription and monitoring the changes induced on aerobic endurance after a period of increased training volume in young swimmers. An experimental group (E: n = 7; age: 13.3 ± 1.3 years), which participated in competitive training was tested at the beginning (W0), the sixth week (W6), and 14th week (W14) to compare the changes of aerobic endurance indexes (CV; lactate threshold [LT]; velocity corresponding to blood lactate concentration of 4 mmol · L: V4). A control group (C: n = 7; age: 14.1 ± 1.6 years), which refrained from competitive training, was used to observe maturation effects and was tested for CV changes between W0 and W14. The average weekly training volume was increased after the sixth week in the E group and was unchanged for the C group. The CV was not different between or within groups at W0 and W14 (p > 0.05). The LT of the E group was no different compared to V4 and CV at W0 and W6 (p > 0.05) but was higher than CV at W14 (p 0.05). LT, V4, and CV were unchanged despite the increased training volume from W6 to W14 (LT: 1.2 ± 4.3%, V4: 0.8 ± 1.5%, CV: 0.3 ± 0.8%; p > 0.05). These findings suggest that CV pace may be effectively used for the improvement of aerobic endurance in young swimmers. The aerobic endurance indexes used for the assessment of swimmers' progression showed different rates of change as a response to the same training stimulus and cannot be used interchangeably for training planning.

  10. A suction detection system for rotary blood pumps based on the Lagrangian support vector machine algorithm.

    Science.gov (United States)

    Wang, Yu; Simaan, Marwan A

    2013-05-01

    The Left Ventricular Assist Device (LVAD) is a rotary mechanical pump that is implanted in patients with congestive heart failure to help the left ventricle in pumping blood in the circulatory system. However, using such a device may result in a very dangerous event, called ventricular suction that can cause ventricular collapse due to overpumping of blood from the left ventricle when the rotational speed of the pump is high. Therefore, a reliable technique for detecting ventricular suction is crucial. This paper presents a new suction detection system that can precisely classify pump flow patterns, based on a Lagrangian Support Vector Machine (LSVM) model that combines six suction indices extracted from the pump flow signal to make a decision about whether the pump is in suction, approaching suction, or not in suction. The proposed method has been tested using in vivo experimental data based on two different pumps. The simulation results show that the system can produce superior performance in terms of classification accuracy, stability, learning speed, and good robustness compared to three other existing suction detection methods and the original SVM-based algorithm. The ability of the proposed algorithm to detect suction provides a reliable platform for the development of a feedback control system to control the speed of the pump while at the same time ensuring that suction is avoided.

  11. Relations between diabetes, blood pressure and aortic pulse wave velocity in haemodialysis patients

    DEFF Research Database (Denmark)

    Peters, Christian Daugaard; Kjærgaard, Krista Dybtved; Dzeko, Mirela;

    Diabetes (DM) is common in haemodialysis (HD) patients and affects both blood pressure (BP) and arterial stiffness. Carotid femoral pulse wave velocity (PWV) reflects the stiffness of the aorta and is regarded as a strong risk factor for cardiovascular (CV) mortality in HD patients. However, PWV...... is highly influenced by the BP-level. Higher PWV-values among HD patients with DM could reflect a higher BP-level rather than increased arterial stiffness. The aim of this study was to investigate the effect of DM on BP and PWV in a group of HD patients. BP and PWV were measured in 66 HD patients without DM...... (HD) and 32 HD patients with DM (HD+DM). The SphygmoCor system was used for estimation of PWV. HD-duration, age, gender and BP medication were similar in the two groups. Mean DM-duration was 23±11 years and 25(78%) had type 2 DM. HD+DM had higher BMI (26±5 vs. 29±5 kg/m2, p=0.02), systolic BP (142...

  12. Regional differences in the cerebral blood flow velocity response to hypobaric hypoxia at high altitudes.

    Science.gov (United States)

    Feddersen, Berend; Neupane, Pritam; Thanbichler, Florian; Hadolt, Irmgard; Sattelmeyer, Vera; Pfefferkorn, Thomas; Waanders, Robb; Noachtar, Soheyl; Ausserer, Harald

    2015-11-01

    Symptoms of acute mountain sickness (AMS) may appear above 2,500 m altitude, if the time allowed for acclimatization is insufficient. As the mechanisms underlying brain adaptation to the hypobaric hypoxic environment are not fully understood, a prospective study was performed investigating neurophysiological changes by means of near infrared spectroscopy, electroencephalograpy (EEG), and transcranial doppler sonography at 100, 3,440 and 5,050 m above sea level in the Khumbu Himal, Nepal. Fourteen of the 26 mountaineers reaching 5,050 m altitude developed symptoms of AMS between 3,440 and 5,050 m altitude (Lake-Louise Score ⩾3). Their EEG frontal beta activity and occipital alpha activity increased between 100 and 3,440 m altitude, i.e., before symptoms appeared. Cerebral blood flow velocity (CBFV) in the anterior and middle cerebral arteries (MCAs) increased in all mountaineers between 100 and 3,440 m altitude. During further ascent to 5,050 altitude, mountaineers with AMS developed a further increase in CBFV in the MCA, whereas in all mountaineers CBFV decreased continuously with increasing altitude in the posterior cerebral arteries. These results indicate that hypobaric hypoxia causes different regional changes in CBFV despite similar electrophysiological changes.

  13. Laser Doppler measurement of relative blood velocity in the human optic nerve head.

    Science.gov (United States)

    Riva, C E; Grunwald, J E; Sinclair, S H

    1982-02-01

    The Doppler shift frequency spectrum (DSFS) of laser light scattered from red blood cells (RBCs) moving in the microcirculation of the optic nerve head has been recorded in normal volunteers by means of a fundus camera laser Doppler velocimeter. The width of the DSFS, which varies in proportion to the speed of the RBCs, has been characterized by a parameter alpha. With the use of a model for the scattering of light by tissue and RBCs and for the RBC velocity distribution, values of alpha recorded at normal intraocular pressure (IOP) suggest that the RBCs that contribute to the Doppler signal are flowing in capillaries. The parameter alpha was found to vary markedly with the IOP and with the phase of the ocular pressure pulse at elevated IOP. The return of the speed of RBCs toward normal, which is observed after a step increase of IOP above normal and after a step decrease below normal, has been attributed to an autoregulatory response of the optic nerve circulation.

  14. A Hybrid Windkessel Model of Blood Flow in Arterial Tree Using Velocity Profile Method

    Science.gov (United States)

    Aboelkassem, Yasser; Virag, Zdravko

    2016-11-01

    For the study of pulsatile blood flow in the arterial system, we derived a coupled Windkessel-Womersley mathematical model. Initially, a 6-elements Windkessel model is proposed to describe the hemodynamics transport in terms of constant resistance, inductance and capacitance. This model can be seen as a two compartment model, in which the compartments are connected by a rigid pipe, modeled by one inductor and resistor. The first viscoelastic compartment models proximal part of the aorta, the second elastic compartment represents the rest of the arterial tree and aorta can be seen as the connection pipe. Although the proposed 6-elements lumped model was able to accurately reconstruct the aortic pressure, it can't be used to predict the axial velocity distribution in the aorta and the wall shear stress and consequently, proper time varying pressure drop. We then modified this lumped model by replacing the connection pipe circuit elements with a vessel having a radius R and a length L. The pulsatile flow motions in the vessel are resolved instantaneously along with the Windkessel like model enable not only accurate prediction of the aortic pressure but also wall shear stress and frictional pressure drop. The proposed hybrid model has been validated using several in-vivo aortic pressure and flow rate data acquired from different species such as, humans, dogs and pigs. The method accurately predicts the time variation of wall shear stress and frictional pressure drop. Institute for Computational Medicine, Dept. Biomedical Engineering.

  15. Heat stress exacerbates the reduction in middle cerebral artery blood velocity during prolonged self-paced exercise.

    Science.gov (United States)

    Périard, J D; Racinais, S

    2015-06-01

    This study examined the influence of hyperthermia on middle cerebral artery mean blood velocity (MCA Vmean). Eleven cyclists undertook a 750 kJ self-paced time trial in HOT (35 °C) and COOL (20 °C) conditions. Exercise time was longer in HOT (56 min) compared with COOL (49 min; P heat appears to have exacerbated the reduction in MCA Vmean, in part via increases in peripheral blood flow and a decrease in arterial blood pressure.

  16. Assessment of blood flow velocity and pulsatility in cerebral perforating arteries with 7-T quantitative flow MRI.

    Science.gov (United States)

    Bouvy, W H; Geurts, L J; Kuijf, H J; Luijten, P R; Kappelle, L J; Biessels, G J; Zwanenburg, J J M

    2016-09-01

    Thus far, blood flow velocity measurements with MRI have only been feasible in large cerebral blood vessels. High-field-strength MRI may now permit velocity measurements in much smaller arteries. The aim of this proof of principle study was to measure the blood flow velocity and pulsatility of cerebral perforating arteries with 7-T MRI. A two-dimensional (2D), single-slice quantitative flow (Qflow) sequence was used to measure blood flow velocities during the cardiac cycle in perforating arteries in the basal ganglia (BG) and semioval centre (CSO), from which a mean normalised pulsatility index (PI) per region was calculated (n = 6 human subjects, aged 23-29 years). The precision of the measurements was determined by repeated imaging and performance of a Bland-Altman analysis, and confounding effects of partial volume and noise on the measurements were simulated. The median number of arteries included was 14 in CSO and 19 in BG. In CSO, the average velocity per volunteer was in the range 0.5-1.0 cm/s and PI was 0.24-0.39. In BG, the average velocity was in the range 3.9-5.1 cm/s and PI was 0.51-0.62. Between repeated scans, the precision of the average, maximum and minimum velocity per vessel decreased with the size of the arteries, and was relatively low in CSO and BG compared with the M1 segment of the middle cerebral artery. The precision of PI per region was comparable with that of M1. The simulations proved that velocities can be measured in vessels with a diameter of more than 80 µm, but are underestimated as a result of partial volume effects, whilst pulsatility is overestimated. Blood flow velocity and pulsatility in cerebral perforating arteries have been measured directly in vivo for the first time, with moderate to good precision. This may be an interesting metric for the study of haemodynamic changes in aging and cerebral small vessel disease. © 2015 The Authors NMR in Biomedicine Published by John Wiley & Sons Ltd.

  17. Differential increases in blood flow velocity in the middle cerebral artery after tourniquet deflation during sevoflurane, isoflurane or propofol anaesthesia.

    Science.gov (United States)

    Kadoi, Y; Kawauchi, C H; Ide, M; Saito, S; Mizutani, A

    2009-07-01

    The purpose of this study was to examine the comparative effects of sevoflurane, isoflurane or propofol on cerebral blood flow velocity after tourniquet deflation during orthopaedic surgery. Thirty patients undergoing elective orthopaedic surgery were randomly divided into sevoflurane, isoflurane and propofol groups. Anaesthesia was maintained with sevoflurane, isoflurane or propofol infusion in 33% oxygen and 67% nitrous oxide, in whatever concentrations were necessary to keep bispectral index values between 45 and 50. Ventilatory rate or tidal volume was adjusted to target PaCO2 of 35 mmHg. A 2.0 MHz transcranial Doppler probe was attached to the patient's head at the temporal window and mean blood flow velocity in the middle cerebral artery was continuously measured. The extremity was exsanguinated with an Esmarch bandage and the pneumatic tourniquet was inflated to a pressure of 450 mmHg. Arterial blood pressure, heart rate, velocity in the middle cerebral artery and arterial blood gas analysis were measured every minute for 10 minutes after release of the tourniquet in all three groups. Velocity in the middle cerebral artery in the three groups increased for five minutes after tourniquet deflation. Because of the different cerebrovascular effects of the three agents, the degree of increase in flow velocity in the isoflurane group was greater than in the other two groups, the change in flow velocity in the propofol group being the lowest (at three minutes after deflation 40 +/- 7%, 32 +/- 6% and 28 +/- 10% in the isoflurane, sevoflurane and propofol groups respectively, P < 0.05).

  18. Urban forests as hubs for novel zoonosis: blood meal analysis, seasonal variation in Culicoides (Diptera: Ceratopogonidae) vectors, and avian haemosporidians.

    Science.gov (United States)

    Santiago-Alarcon, Diego; Havelka, Peter; Pineda, Eduardo; Segelbacher, Gernot; Schaefer, H Martin

    2013-12-01

    Culicoides vectors can transmit a diverse array of parasites and are globally distributed. We studied feeding preferences and seasonal variation of Culicoides (Diptera: Ceratopogonidae) vectors in an urban forest of Germany to determine whether humans living nearby are readily exposed to vector-borne parasites from wild animals. We used a fragment of the mtDNA COI gene to identify hosts from blood meals. We amplified a fragment of the mtDNA cyt b to detect haemosporidian infections in Culicoides abdomens and thoraxes. We detected a total of 22 Culicoides species. Fifty-eight blood meals (84%) were from humans, 10 from birds, and one from livestock. We found Culicoides kibunensis (considered ornithophilic) with 29 human blood meals. Host generalist Culicoides festivipennis and Culicoides obsoletus had 14 human blood meals. Culicoides clastrieri and Culicoides semimaculatus fed on birds; previously humans were their only known host. Six thoraxes and three abdomens were infected with either Haemoproteus pallidulus or Haemoproteus parabelopolskyi. There were changes in Culicoides community structure across months. Culicoides pictipennis was the dominant species during spring, C. kibunensis and C. clastrieri were dominant during summer, and C. obsoletus was dominant by early autumn. All dominant species were generalists feeding on birds, livestock and humans. Our results indicate that humans can serve as a blood source for dominant Culicoides species instead of the normal wild animal hosts in urban areas.

  19. Productive infection of human peripheral blood mononuclear cells by feline immunodeficiency virus: implications for vector development.

    Science.gov (United States)

    Johnston, J; Power, C

    1999-03-01

    Feline immunodeficiency virus (FIV) is a lentivirus causing immune suppression and neurological disease in cats. Like primate lentiviruses, FIV utilizes the chemokine receptor CXCR4 for infection. In addition, FIV gene expression has been demonstrated in immortalized human cell lines. To investigate the extent and mechanism by which FIV infected primary and immortalized human cell lines, we compared the infectivity of two FIV strains, V1CSF and Petaluma, after cell-free infection. FIV genome was detected in infected human peripheral blood mononuclear cells (PBMC) and macrophages at 21 and 14 days postinfection, respectively. Flow cytometry analysis of FIV-infected human PBMC indicated that antibodies to FIV p24 recognized 12% of the cells. Antibodies binding the CCR3 chemokine receptor maximally inhibited infection of human PBMC by both FIV strains compared to antibodies to CXCR4 or CCR5. Reverse transcriptase levels increased in FIV-infected human PBMC, with detection of viral titers of 10(1.3) to 10(2.1) 50% tissue culture infective doses/10(6) cells depending on the FIV strain examined. Cell death in human PBMC infected with either FIV strain was significantly elevated relative to uninfected control cultures. These findings indicate that FIV can productively infect primary human cell lines and that viral strain specificity should be considered in the development of an FIV vector for gene therapy.

  20. Velocity field measurements of valvular blood flow in a human superficial vein using high-frequency ultrasound speckle image velocimetry.

    Science.gov (United States)

    Nam, Kweon-Ho; Yeom, Eunseop; Ha, Hojin; Lee, Sang-Joon

    2012-01-01

    This study aims to investigate the blood flow around the perivalvular area in a human superficial vein using high-frequency ultrasound (HFUS) speckle image velocimetry. HFUS B-mode images were captured from the superficial veins of human lower extremity with a 35-MHz transducer. To measure the instantaneous velocity fields of blood flow, a cross-correlation particle image velocimetry (PIV) algorithm was applied to two B-mode images that were captured consecutively. The echo speckles of red blood cells (RBCs) were used as flow tracers. In the vicinity of the venous valve, the opening and closing motions of valve cusps were simultaneously visualized with the phasic variation of velocity fields. Large-scale vortices were observed behind the sinus pockets while the main bloodstream was directed proximally. This measurement technique combining PIV algorithm and HFUS B-mode imaging was found to be unique and useful for investigating the hemodynamic characteristics of blood flow in the perivalvular area and for diagnosing venous insufficiency and valve abnormality in superficial blood vessels.

  1. Biostable insect kinin analogs reduce blood meal and disrupt ecdysis in the blood-gorging Chagas’ disease vector, Rhodnius prolixus

    Science.gov (United States)

    Rhodnius prolixus is a blood-gorging hemipteran that takes blood meals that are approximately 10 times its body weight. This blood meal is crucial for growth and development and is needed to ensure a successful molt into the next instar. Kinins are a multifunctional family of neuropeptides which hav...

  2. The relationship between onset of blood lactate accumulation, critical velocity, and maximal lactate steady state in soccer players.

    Science.gov (United States)

    Denadai, Benedito Sérgio; Gomide, Euripedes Barsanulfo Gonçalves; Greco, Camila Coelho

    2005-05-01

    The objective of this study was to analyze the validity of the velocity corresponding to the onset of blood lactate accumulation (OBLA) and critical velocity (CV) to determine the maximal lactate steady state (MLSS) in soccer players. Twelve male soccer players (21.5 +/- 1.0 years) performed an incremental treadmill test for the determination of OBLA. The velocity corresponding to OBLA (3.5 mM of blood lactate) was determined through linear interpolation. The subjects returned to the laboratory on 7 occasions for the determination of MLSS and CV. The MLSS was determined from 5 treadmill runs of up to 30-minute duration and defined as the highest velocity at which blood lactate did not increase by more than 1 mM between minutes 10 and 30 of the constant velocity runs. The CV was determined by 2 maximal running efforts of 1,500 and 3,000 m performed on a 400-m running track. The CV was calculated as the slope of the linear regression of distance run versus time. Analysis of variance revealed no significant differences between OBLA (13.6 +/- 1.4 km.h(-1)) and MLSS (13.1 +/- 1.2 km.h(-1)) and between OBLA and CV (14.4 +/- 1.1 km.h(-1)). The CV was significantly higher than the MLSS. There was a significant correlation between MLSS and OBLA (r = 0.80), MLSS and CV (r = 0.90), and OBLA and CV (r = 0.80). We can conclude that the OBLA can be utilized in soccer players to estimate the MLSS. In this group of athletes, however, CV does not represent a sustainable steady-state exercise intensity.

  3. Absolute Geostrophic Velocity Inverted from World Ocean Atlas 2013 (WOAV13) with the P-Vector Method

    Science.gov (United States)

    2015-11-01

    sea floor (5500 m depth) (Boyer et al. 2005; Locarnini et al., 2013; Zweng et al. 2013). It also includes associated statistical fields of observed...current velocity data. Inclusion of ocean current velocity data into the WOA13 becomes important for climatic and oceanographic studies. Absolute

  4. Detection of number of sources and DOA stimation based on the combined information processing of pressure and particle velocity using acoustic vector sensor array

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to solve the problem of DOA (direction of arrival) estimation of underwater remote targets, a novel subspace-decomposition method based on the cross covariance matrix of the pressure and the particle velocity of acoustic vector sensor arrays (AVSA) was proposed.Whereafter, using spatio-temporal virtual tapped-delay-line, a new eigenvector-based criteria of detection of number of sources and of subspace partition is also presented. The theoretical analysis shows that the new source detection and direction finding method is different from existing AVSA based DOA estimation methods using particle velocity information of acoustic vector sensor (AVS) as an independent array element. It is entirely based on the combined information processing of pressure and particle velocity, has better estimation performance than existing methods in isotropic noise field. Computer simulations with data from lake trials demonstrate, the proposed method is effective and obviously outperforms existing methods in resolution and accuracy in the case of low signal-to-noise ratio (SNR).

  5. Wideband high-resolution direction of arrival estimation method based on the pressure-velocity combined processing using the acoustic vector sensor array

    Institute of Scientific and Technical Information of China (English)

    BAI Xingyu; YANG Desen; ZHAO Chunhui

    2007-01-01

    In order to solve the problem of DOA (Direction of Arrival) estimation of underwater distant wideband targets, a novel coherent signal-subspace method based on the cross spectral matrix of pressure and particle velocity using the Acoustic Vector Sensor Array (AVSA)is proposed in this paper. The proposed method is different from existing AVSA based DOA estimation methods in using particle velocity information of Acoustic Vector Sensor (AVS) as an independent array element. It is entirely based on the combined information processing of pressure and particle velocity, namely, the P-V cross spectrum, has better DOA estimation performance than existing methods in isotropic noise field. By theoretical analysis, both focusing principle and eigendecomposition theory based on the P-V cross spectral matrix are given.At the same time, the corresponding criteria for source number detection is also presented.Computer simulations with data from lake trials demonstrate that the proposed method is effective and obviously outperforms existing methods in resolution and accuracy in the case of low Signal-to-Noise Ratio (SNR).

  6. Generation of integration-free human induced pluripotent stem cells from postnatal blood mononuclear cells by plasmid vector expression.

    Science.gov (United States)

    Dowey, Sarah N; Huang, Xiaosong; Chou, Bin-Kuan; Ye, Zhaohui; Cheng, Linzhao

    2012-11-01

    Several human postnatal somatic cell types have been successfully reprogrammed to induced pluripotent stem cells (iPSCs). Blood mononuclear cells (MNCs) offer several advantages compared with other cell types. They are easily isolated from umbilical cord blood (CB) or adult peripheral blood (PB), and can be used fresh or after freezing. A short culture allows for more efficient reprogramming, with iPSC colonies forming from blood MNCs in 14 d, compared with 28 d for age-matched fibroblastic cells. The advantages of briefly cultured blood MNCs may be due to favorable epigenetic profiles and gene expression patterns. Blood cells from adults, especially nonlymphoid cells that are replenished frequently from intermittently activated blood stem cells, are short-lived in vivo and may contain less somatic mutations than skin fibroblasts, which are more exposed to environmental mutagens over time. We describe here a detailed, validated protocol for effective generation of integration-free human iPSCs from blood MNCs by plasmid vectors.

  7. The effect of the prior flow velocity on the structural organization of aggregated erythrocytes in the quiescent blood.

    Science.gov (United States)

    Pribush, Alexander; Meyerstein, Dan; Meyerstein, Naomi

    2011-02-01

    Usually, investigations of erythrocyte aggregation at rest are focused on effects of the strength of erythrocyte-erythrocyte attractive interactions and the volume fraction of the cells, whereas the role of prior flow velocity has not been thoroughly investigated. The aim of this study is to fill this gap. The main conclusions extracted from time records of the complex admittance of blood are as follows: (1) Dispersion of blood in a prior flow into discrete aggregates increases the mesh size of network, which, as has been recently shown, is formed in the quiescent blood. (2) If the energy of the flow field is sufficient to prevent the formation of face-to-side intercellular links, so that the dispersed phase consists of linear rouleaux, changes in the mesh size correlate positively with the length of rouleaux. (3) At slower prior flow velocities, the cells are combined into branched aggregates. As the degree of branching increases, the effect becomes less important. (4) The effects of the length of linear rouleaux and the degree of branching of ramified aggregates on the mesh size are qualitatively similar for suspensions with different aggregating media. (5) Erythrocytes suspended in strongly aggregating media form at low flow conditions a network-like structure. In this case, unlike high and moderate prior flow regimes, the mesh size of RBC network at rest is less than that formed after the stoppage of completely dispersed blood.

  8. World Ocean Geostrophic Velocity Inverted from World Ocean Atlas 2013 with the P-Vector Method (NODC Accession 0121576)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset comprises 3D gridded climatological fields of geostrophic velocity inverted from World Ocean Atlas-2013 (WOA2013) temperature and salinity fields using...

  9. New type of Sendai virus vector provides transgene-free iPS cells derived from chimpanzee blood.

    Directory of Open Access Journals (Sweden)

    Yasumitsu Fujie

    Full Text Available Induced pluripotent stem cells (iPSCs are potentially valuable cell sources for disease models and future therapeutic applications; however, inefficient generation and the presence of integrated transgenes remain as problems limiting their current use. Here, we developed a new Sendai virus vector, TS12KOS, which has improved efficiency, does not integrate into the cellular DNA, and can be easily eliminated. TS12KOS carries KLF4, OCT3/4, and SOX2 in a single vector and can easily generate iPSCs from human blood cells. Using TS12KOS, we established iPSC lines from chimpanzee blood, and used DNA array analysis to show that the global gene-expression pattern of chimpanzee iPSCs is similar to those of human embryonic stem cell and iPSC lines. These results demonstrated that our new vector is useful for generating iPSCs from the blood cells of both human and chimpanzee. In addition, the chimpanzee iPSCs are expected to facilitate unique studies into human physiology and disease.

  10. Influence of the velocity vector base relocation to the center of mass of the interrogation area on PIV accuracy

    Directory of Open Access Journals (Sweden)

    Kouba Jan

    2014-03-01

    Full Text Available This paper is aimed at modification of calculation algorithm used in data processing from PIV (Particle Image Velocimetry method. The modification of standard Multi-step correlation algorithm is based on imaging the centre of mass of the interrogation area to define the initial point of the respective vector, instead of the geometrical centre. This paper describes the principle of initial point-vector assignment, the corresponding data processing methodology including the test track analysis. Both approaches are compared within the framework of accuracy in the conclusion. The accuracy test is performed using synthetic and real data.

  11. Novel measurement of blood velocity profile using translating-stage optical method and theoretical modeling based on non-Newtonian viscosity model

    Science.gov (United States)

    Kim, Chang-Beom; Lim, Jaeho; Hong, Hyobong; Kresh, J. Yasha; Wootton, David M.

    2015-07-01

    Detailed knowledge of the blood velocity distribution over the cross-sectional area of a microvessel is important for several reasons: (1) Information about the flow field velocity gradients can suggest an adequate description of blood flow. (2) Transport of blood components is determined by the velocity profiles and the concentration of the cells over the cross-sectional area. (3) The velocity profile is required to investigate volume flow rate as well as wall shear rate and shear stress which are important parameters in describing the interaction between blood cells and the vessel wall. The present study shows the accurate measurement of non-Newtonian blood velocity profiles at different shear rates in a microchannel using a novel translating-stage optical method. Newtonian fluid velocity profile has been well known to be a parabola, but blood is a non-Newtonian fluid which has a plug flow region at the centerline due to yield shear stress and has different viscosities depending on shear rates. The experimental results were compared at the same flow conditions with the theoretical flow equations derived from Casson non-Newtonian viscosity model in a rectangular capillary tube. And accurate wall shear rate and shear stress were estimated for different flow rates based on these velocity profiles. Also the velocity profiles were modeled and compared with parabolic profiles, concluding that the wall shear rates were at least 1.46-3.94 times higher than parabolic distribution for the same volume flow rate.

  12. The effects of graded changes in oxygen and carbon dioxide tension on coronary blood velocity independent of myocardial energy demand.

    Science.gov (United States)

    Boulet, Lindsey M; Stembridge, Mike; Tymko, Michael M; Tremblay, Joshua C; Foster, Glen E

    2016-08-01

    In humans, coronary blood flow is tightly regulated by microvessels within the myocardium to match myocardial energy demand. However, evidence regarding inherent sensitivity of the microvessels to changes in arterial partial pressure of carbon dioxide and oxygen is conflicting because of the accompanied changes in myocardial energy requirements. This study aimed to investigate the changes in coronary blood velocity while manipulating partial pressures of end-tidal CO2 (Petco2) and O2 (Peto2). It was hypothesized that an increase in Petco2 (hypercapnia) or decrease in Peto2 (hypoxia) would result in a significant increase in mean blood velocity in the left anterior descending artery (LADVmean) due to an increase in both blood gases and energy demand associated with the concomitant cardiovascular response. Cardiac energy demand was assessed through noninvasive measurement of the total left ventricular mechanical energy. Healthy subjects (n = 13) underwent a euoxic CO2 test (Petco2 = -8, -4, 0, +4, and +8 mmHg from baseline) and an isocapnic hypoxia test (Peto2 = 64, 52, and 45 mmHg). LADVmean was assessed using transthoracic Doppler echocardiography. Hypercapnia evoked a 34.6 ± 8.5% (mean ± SE; P < 0.01) increase in mean LADVmean, whereas hypoxia increased LADVmean by 51.4 ± 8.8% (P < 0.05). Multiple stepwise regressions revealed that both mechanical energy and changes in arterial blood gases are important contributors to the observed changes in LADVmean (P < 0.01). In summary, regulation of the coronary vasculature in humans is mediated by metabolic changes within the heart and an inherent sensitivity to arterial blood gases.

  13. Transcranial Doppler-determined change in posterior cerebral artery blood flow velocity does not reflect vertebral artery blood flow during exercise.

    Science.gov (United States)

    Washio, Takuro; Sasaki, Hiroyuki; Ogoh, Shigehiko

    2017-02-10

    We examined whether a change in posterior cerebral artery flow velocity (PCAv) reflected the posterior cerebral blood flow, in healthy subjects, during both static and dynamic exercise. PCAv and vertebral artery (VA) blood flow, as an index of posterior blood flow, were continuously measured during an exercise trial, using transcranial Doppler (TCD) ultrasonography and Doppler ultrasound, respectively. Static handgrip exercise significantly increased both PCAv and VA blood flow. Increasing intensity of dynamic exercise further increased VA blood flow from moderate exercise, while PCAv decreased to almost resting level. During both static and dynamic exercise, the PCA cerebrovascular conductance (CVC) index significantly decreased from rest (static and high intensity dynamic exercise; -11.5 ± 12.2% and -18.0 ± 16.8%; mean ± SD, respectively), despite no change in the CVC of VA. These results indicate that vasoconstriction occurred at PCA but not VA during exercise-induced hypertension. This discrepancy in vascular response to exercise between PCA and VA may be due to different cerebral arterial characteristics. Therefore, to determine the effect of exercise on posterior cerebral circulation, at least, we need to consider carefully which cerebral artery to measure, regardless of exercise mode.

  14. The hot-film anemometer--a method for blood velocity determination. II. In vivo comparison with the electromagnetic blood flowmeter.

    Science.gov (United States)

    Paulsen, P K

    1980-01-01

    Using a constant temperature hot-film anemometer and an electromagnetic blood flowmeter, volumetric flows and velocity profiles were registered in the pulmonary artery, ascending aorta, abdominal aorta and superior vena cava of mongrel dogs. The anemometer registered in 3 out of 4 dogs in the ascending aorta and in 4 out of 5 dogs in the pulmonary artery. The flow profile in these two vessels was flat with a slight deviation with the highest velocity nearer to the posterior wall. In the abdominal aorta the flow profile was sinusoid and in the superior vena cava irregular. In 22 simultaneous measurements anemometer mean results were 97 +/- 23% (+/- SD) of flowmeter results and peak results correspondingly 113 +/- 23%. None of these differences were significant. It is stressed that both qualitatively and quantitatively hot-film anemometer results are comparable to electromagnetic flowmeter results. However, certain differences have been demonstrated.

  15. Differential effects of hyperventilation on cerebral blood flow velocity after tourniquet deflation during sevoflurane, isoflurane, or propofol anesthesia.

    Science.gov (United States)

    Hinohara, Hiroshi; Kadoi, Yuji; Ide, Masanobu; Kuroda, Masataka; Saito, Shigeru; Mizutani, Akio

    2010-08-01

    The purpose of this study was to compare the degree of increase in middle cerebral artery (MCA) blood flow velocity after tourniquet deflation when modulating hyperventilation during orthopedic surgery under sevoflurane, isoflurane, or propofol anesthesia. Twenty-four patients undergoing elective orthopedic surgery were randomly divided into sevoflurane, isoflurane, and propofol groups. Anesthesia was maintained with sevoflurane, isoflurane, or propofol administration with 33% oxygen and 67% nitrous oxide at anesthetic drug concentrations adequate to maintain bispectral values between 45 and 50. A 2.0-MHz transcranial Doppler probe was attached to the patient's head at the temporal window, and mean blood flow velocity in the MCA (V (mca)) was continuously measured. The extremity was exsanguinated with an Esmarch bandage, and the pneumatic tourniquet was inflated to a pressure of 450 mmHg. Arterial blood pressure, heart rate, V (mca) and arterial blood gases were measured every minute for 10 min after release of the tourniquet in all three groups. Immediately after tourniquet release, the patients' respiratory rates were increased to tightly maintain end-tidal carbon dioxide (PetCO(2)) at 35 mmHg. No change in partial pressure of carbon dioxide in arterial blood (PaCO(2)) was observed pre- and posttourniquet deflation in any of the three groups. Increase in V (mca) in the isoflurane group was greater than that in the other two groups after tourniquet deflation. In addition, during the study period, no difference in V (mca) after tourniquet deflation was observed between the propofol and sevoflurane groups. Hyperventilation could prevent an increase in V (mca) in the propofol and sevoflurane groups after tourniquet deflation. However, hyperventilation could not prevent an increase in V (mca) in the isoflurane group.

  16. Correlation of pulse wave velocity with left ventricular mass in patients with hypertension once blood pressure has been normalized

    Directory of Open Access Journals (Sweden)

    Siu H. Chan

    2012-02-01

    Full Text Available Vascular stiffness has been proposed as a simple method to assess arterial loading conditions of the heart which induce left ventricular hypertrophy (LVH. There is some controversy as to whether the relationship of vascular stiffness to LVH is independent of blood pressure, and which measurement of arterial stiffness, augmentation index (AI or pulse wave velocity (PWV is best. Carotid pulse wave contor and pulse wave velocity of patients (n=20 with hypertension whose blood pressure (BP was under control (<140/90 mmHg with antihypertensive drug treatment medications, and without valvular heart disease, were measured. Left ventricular mass, calculated from 2D echocardiogram, was adjusted for body size using two different methods: body surface area and height. There was a significant (P<0.05 linear correlation between LV mass index and pulse wave velocity. This was not explained by BP level or lower LV mass in women, as there was no significant difference in PWV according to gender (1140.1+67.8 vs 1110.6+57.7 cm/s. In contrast to PWV, there was no significant correlation between LV mass and AI. In summary, these data suggest that aortic vascular stiffness is an indicator of LV mass even when blood pressure is controlled to less than 140/90 mmHg in hypertensive patients. The data further suggest that PWV is a better proxy or surrogate marker for LV mass than AI and the measurement of PWV may be useful as a rapid and less expensive assessment of the presence of LVH in this patient population.

  17. 3D Position and Velocity Vector Computations of Objects Jettisoned from the International Space Station Using Close-Range Photogrammetry Approach

    Science.gov (United States)

    Papanyan, Valeri; Oshle, Edward; Adamo, Daniel

    2008-01-01

    Measurement of the jettisoned object departure trajectory and velocity vector in the International Space Station (ISS) reference frame is vitally important for prompt evaluation of the object s imminent orbit. We report on the first successful application of photogrammetric analysis of the ISS imagery for the prompt computation of the jettisoned object s position and velocity vectors. As post-EVA analyses examples, we present the Floating Potential Probe (FPP) and the Russian "Orlan" Space Suit jettisons, as well as the near-real-time (provided in several hours after the separation) computations of the Video Stanchion Support Assembly Flight Support Assembly (VSSA-FSA) and Early Ammonia Servicer (EAS) jettisons during the US astronauts space-walk. Standard close-range photogrammetry analysis was used during this EVA to analyze two on-board camera image sequences down-linked from the ISS. In this approach the ISS camera orientations were computed from known coordinates of several reference points on the ISS hardware. Then the position of the jettisoned object for each time-frame was computed from its image in each frame of the video-clips. In another, "quick-look" approach used in near-real time, orientation of the cameras was computed from their position (from the ISS CAD model) and operational data (pan and tilt) then location of the jettisoned object was calculated only for several frames of the two synchronized movies. Keywords: Photogrammetry, International Space Station, jettisons, image analysis.

  18. Comparative study of shape, intensity and texture features and support vector machine for white blood cell classification

    Directory of Open Access Journals (Sweden)

    Mehdi Habibzadeh

    2013-04-01

    Full Text Available The complete blood count (CBC is widely used test for counting and categorizing various peripheral particles in the blood. The main goal of the paper is to count and classify white blood cells (leukocytes in microscopic images into five major categories using features such as shape, intensity and texture features. The first critical step of counting and classification procedure involves segmentation of individual cells in cytological images of thin blood smears. The quality of segmentation has significant impact on the cell type identification, but poor quality, noise, and/or low resolution images make segmentation less reliable. We analyze the performance of our system for three different sets of features and we determine that the best performance is achieved by wavelet features using the Dual-Tree Complex Wavelet Transform (DT-CWT which is based on multi-resolution characteristics of the image. These features are combined with the Support Vector Machine (SVM which classifies white blood cells into their five primary types. This approach was validated with experiments conducted on digital normal blood smear images with low resolution.

  19. Hunting, Swimming, and Worshiping: Human Cultural Practices Illuminate the Blood Meal Sources of Cave Dwelling Chagas Vectors (Triatoma dimidiata) in Guatemala and Belize

    OpenAIRE

    Lori Stevens; M Carlota Monroy; Antonieta Guadalupe Rodas; Dorn, Patricia L.

    2014-01-01

    Background Triatoma dimidiata, currently the major Central American vector of Trypanosoma cruzi, the parasite that causes Chagas disease, inhabits caves throughout the region. This research investigates the possibility that cave dwelling T. dimidiata might transmit the parasite to humans and links the blood meal sources of cave vectors to cultural practices that differ among locations. Methodology/Principal Findings We determined the blood meal sources of twenty-four T. dimidiata collected fr...

  20. Facial immersion in cold water enhances cerebral blood velocity during breath-hold exercise in humans

    DEFF Research Database (Denmark)

    Kjeld, Thomas; Pott, Frank C; Secher, Niels H

    2009-01-01

    perfusion evaluated as the middle cerebral artery mean flow velocity (MCA V(mean)) during exercise in nine male subjects. At rest, a breath hold of maximum duration increased the arterial carbon dioxide tension (Pa(CO(2))) from 4.2 to 6.7 kPa and MCA V(mean) from 37 to 103 cm/s (mean; approximately 178%; P...

  1. Quantification of blood flow velocity in stenosed arteries by the use of finite elements: an observer-independent noninvasive method.

    Science.gov (United States)

    Mühlthaler, Hannes; Quatember, Bernhard; Fraedrich, Gustav; Mühlthaler, Markus; Pfeifer, Bernhard; Greiner, Andreas; Schocke, Michael F H

    2008-10-01

    Interventions for peripheral arterial disease should be designed to treat a physiological rather than an anatomic defect. Thus, for vascular surgeons, functional information about stenoses is as important as the anatomic one. In case of finding a stenosis by the use of magnetic resonance angiography, it would be a matter of particular interest to derive automatically and directly objective information about the hemodynamic influence on blood flow, caused by patient-specific stenoses. We developed a methodology to noninvasively perform numerical simulations of a patient's hemodynamic state on the basis of magnetic resonance images and by the means of the finite element method. We performed patient-specific three-dimensional simulation studies of the increase in systolic blood flow velocity due to stenoses using the commercial computational fluid dynamic software package FIDAP 8.52. The generation of a mesh defining the flow domain with a stenosis and some simulation results are shown.

  2. The postural reduction in middle cerebral artery blood velocity is not explained by PaCO2

    DEFF Research Database (Denmark)

    Immink, R V; Secher, N H; Roos, C M

    2006-01-01

    In the normocapnic range, middle cerebral artery mean velocity (MCA Vmean) changes approximately 3.5% per mmHg carbon-dioxide tension in arterial blood (PaCO2) and a decrease in PaCO2 will reduce the cerebral blood flow by vasoconstriction (the CO2 reactivity of the brain). When standing up MCA...... Vmean and the end-tidal carbon-dioxide tension (PETCO2) decrease, suggesting that PaCO2 contributes to the reduction in MCA Vmean. In a fixed body position, PETCO2 tracks changes in the PaCO2 but when assuming the upright position, cardiac output (Q) decreases and its distribution over the lung changes...

  3. The influence of transcutaneous electrical neurostimulation (TENS) on human cerebral blood flow velocities

    NARCIS (Netherlands)

    ter Laan, Mark; van Dijk, J. Marc C.; Elting, Jan-Willem J.; Fidler, Vaclav; Staal, Michiel J.

    2010-01-01

    It has been shown that transcutaneous electrical neurostimulation (TENS) reduces sympathetic tone. Spinal cord stimulation (SCS) has proven qualities to improve coronary, peripheral, and cerebral blood circulation. Therefore, we postulate that TENS and SCS affect the autonomic nervous system in anal

  4. Intraoperative vascular anatomy, arterial blood flow velocity, and microcirculation in unilateral and bilateral cleft lip repair

    NARCIS (Netherlands)

    Mueller, A.A.; Schumann, D.; Reddy, R.R.; Schwenzer-Zimmerer, K.; Mueller-Gerbl, M.; Zeilhofer, H.F.; Sailer, H.F.; Reddy, S.G.

    2012-01-01

    BACKGROUND: Cleft lip repair aims to normalize the disturbed anatomy and function. The authors determined whether normalization of blood circulation is achieved. METHODS: The authors measured the microcirculatory flow, oxygen saturation, and hemoglobin level in the lip and nose of controls (n = 22)

  5. A computational model for nitric oxide, nitrite and nitrate biotransport in the microcirculation: effect of reduced nitric oxide consumption by red blood cells and blood velocity.

    Science.gov (United States)

    Deonikar, Prabhakar; Kavdia, Mahendra

    2010-12-01

    Bioavailability of vasoactive endothelium-derived nitric oxide (NO) in vasculature is a critical factor in regulation of many physiological processes. Consumption of NO by RBC plays a crucial role in maintaining NO bioavailability. Recently, Deonikar and Kavdia (2009b) reported an effective NO-RBC reaction rate constant of 0.2×10(5)M(-1)s(-1) that is ~7 times lower than the commonly used NO-RBC reaction rate constant of 1.4×10(5)M(-1)s(-1). To study the effect of lower NO-RBC reaction rate constant and nitrite and nitrate formation (products of NO metabolism in blood), we developed a 2D mathematical model of NO biotransport in 50 and 200μm ID arterioles to calculate NO concentration in radial and axial directions in the vascular lumen and vascular wall of the arterioles. We also simulated the effect of blood velocity on NO distribution in the arterioles to determine whether NO can be transported to downstream locations in the arteriolar lumen. The results indicate that lowering the NO-RBC reaction rate constant increased the NO concentration in the vascular lumen as well as the vascular wall. Increasing the velocity also led to increase in NO concentration. We predict increased NO concentration gradient along the axial direction with an increase in the velocity. The predicted NO concentration was 281-1163nM in the smooth muscle cell layer for 50μm arteriole over the blood velocity range of 0.5-4cms(-1) for k(NO-RBC) of 0.2×10(5)M(-1)s(-1), which is much higher than the reported values from earlier mathematical modeling studies. The NO concentrations are similar to the experimentally measured vascular wall NO concentration range of 300-1000nM in several different vascular beds. The results are significant from the perspective that the downstream transport of NO is possible under the right circumstances.

  6. Blood flow velocity in the Popliteal Vein using Transverse Oscillation Ultrasound

    DEFF Research Database (Denmark)

    Bechsgaard, Thor; Lindskov Hansen, Kristoffer; Brandt, Andreas Hjelm;

    2016-01-01

    Chronic venous disease is a common condition leading to varicose veins, leg edema, post-thrombotic syndrome and venous ulcerations. Ultrasound (US) is the main modality for examination of venous disease. Color Doppler and occasionally spectral Doppler US (SDUS) are used for evaluation of the venous...... in the veins of the lower limbs. Four volunteers were recruited for the study. A standardized flow was provoked with a cuff compression-decompression system placed around the lower leg. The average peak velocity in the popliteal vein of the four volunteers was 151.5 cm/s for SDUS and 105.9 cm/s for TOUS (p

  7. Carotid artery longitudinal wall motion is associated with local blood velocity and left ventricular rotational, but not longitudinal, mechanics.

    Science.gov (United States)

    Au, Jason S; Ditor, David S; MacDonald, Maureen J; Stöhr, Eric J

    2016-07-01

    Recent studies have identified a predictable movement pattern of the common carotid artery wall in the longitudinal direction. While there is evidence that the magnitude of this carotid artery longitudinal wall motion (CALM) is sensitive to cardiovascular health status, little is known about the determinants of CALM The purpose of this integrative study was to evaluate the contribution of left ventricular (LV) cardiac motion and local blood velocity to CALM Simultaneous ultrasound measurements of CALM, common carotid artery mean blood velocity (MBV), and left ventricular motion were performed in ten young, healthy individuals (6 males; 22 ± 1 years). Peak anterograde CALM occurred at a similar time as peak MBV (18.57 ± 3.98% vs. 18.53 ± 2.81% cardiac cycle; t-test: P = 0.94; ICC: 0.79, P longitudinal displacement was not associated with peak CALM (r = 0.11, P = 0.77). These results suggest that the rotational mechanical movement of the LV base may be closely associated with longitudinal mechanics in the carotid artery. This finding may have important implications for interpreting the complex relationship between ventricular and vascular function.

  8. Towards 3C-3D digital holographic fluid velocity vector field measurement—tomographic digital holographic PIV (Tomo-HPIV)

    Science.gov (United States)

    Soria, J.; Atkinson, C.

    2008-07-01

    Most unsteady and/or turbulent flows of geophysical and engineering interest have a highly three-dimensional (3D) complex topology and their experimental investigation is in pressing need of quantitative velocity measurement methods that are robust and can provide instantaneous 3C-3D velocity field data over a significant volumetric domain of the flow. This paper introduces and demonstrates a new method that uses multiple digital CCD array cameras to record in-line digital holograms of the same volume of seed particles from multiple orientations. This technique uses the same basic equipment as Tomo-PIV minus the camera lenses, it overcomes the depth-of-field problem of digital in-line holography and does not require the complex optical calibration of Tomo-PIV. The digital sensors can be oriented in an optimal manner to overcome the depth-of-field limitation of in-line holograms recorded using digital CCD or CMOS array cameras, resulting in a 3D reconstruction of the seed particles within the volume of interest, which can subsequently be analysed using 3D cross-correlation PIV analysis to yield a 3C-3D velocity field. A demonstration experiment of Tomo-HPIV using uniform translation with nominally 11 µm diameter seed particles shows that the 3D displacement derived from 3D cross-correlation Tomo-HPIV analysis can be measured within 5% of the imposed uniform translation, where the imposed uniform translation has an estimated standard uncertainty of 4.3%. So this paper proposes a multi-camera digital holographic imaging 3C-3D PIV method, which is identified as tomographic digital holographic PIV or Tomo-HPIV.

  9. Evaluation of coronary blood flow velocity during cardiac arrest with circulation maintained through mechanical chest compressions in a porcine model

    Directory of Open Access Journals (Sweden)

    Wagner Henrik

    2011-12-01

    Full Text Available Abstract Background Mechanical chest compressions (CCs have been shown capable of maintaining circulation in humans suffering cardiac arrest for extensive periods of time. Reports have documented a visually normalized coronary blood flow during angiography in such cases (TIMI III flow, but it has never been actually measured. Only indirect measurements of the coronary circulation during cardiac arrest with on-going mechanical CCs have been performed previously through measurement of the coronary perfusion pressure (CPP. In this study our aim was to correlate average peak coronary flow velocity (APV to CPP during mechanical CCs. Methods In a closed chest porcine model, cardiac arrest was established through electrically induced ventricular fibrillation (VF in eleven pigs. After one minute, mechanical chest compressions were initiated and then maintained for 10 minutes upon which the pigs were defibrillated. Measurements of coronary blood flow in the left anterior descending artery were made at baseline and during VF with a catheter based Doppler flow fire measuring APV. Furthermore measurements of central (thoracic venous and arterial pressures were also made in order to calculate the theoretical CPP. Results Average peak coronary flow velocity was significantly higher compared to baseline during mechanical chests compressions and this was observed during the entire period of mechanical chest compressions (12 - 39% above baseline. The APV slowly declined during the 10 min period of mechanical chest compressions, but was still higher than baseline at the end of mechanical chest compressions. CPP was simultaneously maintained at > 20 mmHg during the 10 minute episode of cardiac arrest. Conclusion Our study showed good correlation between CPP and APV which was highly significant, during cardiac arrest with on-going mechanical CCs in a closed chest porcine model. In addition APV was even higher during mechanical CCs compared to baseline. Mechanical

  10. Simultaneous mapping of temporally-resolved blood flow velocity and oxygenation in femoral artery and vein during reactive hyperemia

    Directory of Open Access Journals (Sweden)

    Langham Michael C

    2011-10-01

    Full Text Available Abstract Background Post-occlusive hyperemia is often used as a paradigm to evaluate vascular reactivity, for example by measuring post-ischemic flow-mediated dilation, arterial blood flow or temporally resolved venous blood oxygenation (HbO2. Here we demonstrate the feasibility of a simultaneous measurement of blood flow and HbO2 in the femoral circulation as part of a single procedure. Methods A multi-echo GRE pulse sequence was designed and implemented to collect velocity-encoded projections in addition to full-image echoes for field mapping as a means to quantify intravascular magnetic susceptibility. The method's feasibility was evaluated at 3T in a small pilot study involving two groups of healthy subjects (mean ages 26 ± 1.6 and 59 ± 7.3 years, N = 7 and 5, respectively in terms of six parameters characterizing the time-course of reactive hyperemia and their sensitivity to differentiate age effects. The reproducibility was assessed on two of the seven young healthy subjects with three repeated measurements. Results The physiological parameters agree with those obtained with current methods that quantify either velocity or HbO2 alone. Of the six measures of vascular reactivity, one from each group was significantly different in the two subject groups (p Conclusion The proposed method is able quantify multiple parameters that may lead to more detailed assessment of peripheral vascular reactivity in a single cuff paradigm rather than in separate procedures as required previously, thereby improving measurement efficiency and patient comfort.

  11. Facial immersion in cold water enhances cerebral blood velocity during breath-hold exercise in humans

    DEFF Research Database (Denmark)

    Kjeld, Thomas; Pott, Frank C; Secher, Niels H

    2009-01-01

    180-W exercise (from 47 to 53 cm/s), and this increment became larger with facial immersion (76 cm/s, approximately 62%; P brain with a >100% increase in MCA V(mean), largely...... perfusion evaluated as the middle cerebral artery mean flow velocity (MCA V(mean)) during exercise in nine male subjects. At rest, a breath hold of maximum duration increased the arterial carbon dioxide tension (Pa(CO(2))) from 4.2 to 6.7 kPa and MCA V(mean) from 37 to 103 cm/s (mean; approximately 178%; P...... exercise, a breath hold increased Pa(CO(2)) from 5.9 to 8.2 kPa (P

  12. Napoleon Cybulski--Polish pioneer in developing of the device for measuring blood flow velocity.

    Science.gov (United States)

    Pawlik, W W; Konturek, S J; Bilski, R

    2006-04-01

    Napoleon Cybulski (1854-1919) was the most prominent Polish physiologist who chaired the Department of Physiology at the Faculty of Medicine of Jagiellonian University between 1885 and 1919. One of his greatest achievements was the construction of a device for precise measurements of blood movement in the vessels - the photohemotachometer, which provided a better insight into the physiology and pathophysiology of the circulatory system. In the field of endocrinology Cybulski together with Szymonowicz, found out that adrenal extracts contain biologically active substances that elevate blood pressure. He was also a constructor of an extremely clever microcalorimeter to measure the quantity of heat produced during isolated muscle contraction. He applied, for the first time, condensator discharges to stimulate nerves and analyzed changes in the excitability of the muscles. Cybulski proved that the cause of the electrical excitability of tissue depends on the electrical energy and the time of its duration. Together with Beck, he performed the experiments on the sensory centers in the central nervous system by means of the observations of the electrical evoked potentials. They discovered the continuous electrical oscillations in the brain - the brain waves and recorded the negative electrical potentials in certain brain areas induced by sensory impulses coming from the periphery. Using this technique Beck and Cybulski localized various centers in the brain of dogs and Macaccus rhesus monkeys. The names of Beck and Cybulski were quoted in many publications on neurophysiology and electroencephalography. The present paper describes Napoleon Cybulski as a constructor of an original instrument for studying the movement of blood under various experimental conditions an emphasizes the contribution of this invention to the development of physiology.

  13. Novel flow quantification of the carotid bulb and the common carotid artery with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per

    2014-01-01

    Abnormal blood flow is usually assessed using spectral Doppler estimation of the peak systolic velocity. The technique, however, only estimates the axial velocity component, and therefore the complexity of blood flow remains hidden in conventional ultrasound examinations. With the vector ultrasou...

  14. In-Vivo High Dynamic Range Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2015-01-01

    Current vector flow systems are limited in their detectable range of blood flow velocities. Previous work on phantoms has shown that the velocity range can be extended using synthetic aperture directional beamforming combined with an adaptive multi-lag approach. This paper presents a first invivo...

  15. Intraoperative Cardiac Ultrasound Examination Using Vector Flow Imaging

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Pedersen, Mads Møller; Møller-Sørensen, Hasse

    2013-01-01

    Conventional ultrasound (US) methods for blood velocity estimation only provide onedimensional and angle-dependent velocity estimates; thus, the complexity of cardiac flow has been difficult to measure. To circumvent these limitations, the Transverse Oscillation (TO) vector flow method has been...

  16. Aquaporin water channel AgAQP1 in the malaria vector mosquito Anopheles gambiae during blood feeding and humidity adaptation.

    Science.gov (United States)

    Liu, Kun; Tsujimoto, Hitoshi; Cha, Sung-Jae; Agre, Peter; Rasgon, Jason L

    2011-04-12

    Altered patterns of malaria endemicity reflect, in part, changes in feeding behavior and climate adaptation of mosquito vectors. Aquaporin (AQP) water channels are found throughout nature and confer high-capacity water flow through cell membranes. The genome of the major malaria vector mosquito Anopheles gambiae contains at least seven putative AQP sequences. Anticipating that transmembrane water movements are important during the life cycle of A. gambiae, we identified and characterized the A. gambiae aquaporin 1 (AgAQP1) protein that is homologous to AQPs known in humans, Drosophila, and sap-sucking insects. When expressed in Xenopus laevis oocytes, AgAQP1 transports water but not glycerol. Similar to mammalian AQPs, water permeation of AgAQP1 is inhibited by HgCl(2) and tetraethylammonium, with Tyr185 conferring tetraethylammonium sensitivity. AgAQP1 is more highly expressed in adult female A. gambiae mosquitoes than in males. Expression is high in gut, ovaries, and Malpighian tubules where immunofluorescence microscopy reveals that AgAQP1 resides in stellate cells but not principal cells. AgAQP1 expression is up-regulated in fat body and ovary by blood feeding but not by sugar feeding, and it is reduced by exposure to a dehydrating environment (42% relative humidity). RNA interference reduces AgAQP1 mRNA and protein levels. In a desiccating environment (adaptation of A. gambiae, a major mosquito vector of human malaria in sub-Saharan Africa.

  17. Hunting, swimming, and worshiping: human cultural practices illuminate the blood meal sources of cave dwelling Chagas vectors (Triatoma dimidiata in Guatemala and Belize.

    Directory of Open Access Journals (Sweden)

    Lori Stevens

    2014-09-01

    Full Text Available Triatoma dimidiata, currently the major Central American vector of Trypanosoma cruzi, the parasite that causes Chagas disease, inhabits caves throughout the region. This research investigates the possibility that cave dwelling T. dimidiata might transmit the parasite to humans and links the blood meal sources of cave vectors to cultural practices that differ among locations.We determined the blood meal sources of twenty-four T. dimidiata collected from two locations in Guatemala and one in Belize where human interactions with the caves differ. Blood meal sources were determined by cloning and sequencing PCR products amplified from DNA extracted from the vector abdomen using primers specific for the vertebrate 12S mitochondrial gene. The blood meal sources were inferred by ≥ 99% identity with published sequences. We found 70% of cave-collected T. dimidiata positive for human DNA. The vectors had fed on 10 additional vertebrates with a variety of relationships to humans, including companion animal (dog, food animals (pig, sheep/goat, wild animals (duck, two bat, two opossum species and commensal animals (mouse, rat. Vectors from all locations fed on humans and commensal animals. The blood meal sources differ among locations, as well as the likelihood of feeding on dog and food animals. Vectors from one location were tested for T. cruzi infection, and 30% (3/10 tested positive, including two positive for human blood meals.Cave dwelling Chagas disease vectors feed on humans and commensal animals as well as dog, food animals and wild animals. Blood meal sources were related to human uses of the caves. We caution that just as T. dimidiata in caves may pose an epidemiological risk, there may be other situations where risk is thought to be minimal, but is not.

  18. Image segmentation and classification of white blood cells with the extreme learning machine and the fast relevance vector machine.

    Science.gov (United States)

    Ravikumar, S

    2016-05-01

    White blood cells (WBCs) or leukocytes are an important part of the body's defense against infectious organisms and foreign substances. WBC segmentation is a challenging issue because of the morphological diversity of WBCs and the complex and uncertain background of blood smear images. The standard ELM classification techniques are used for WBC segmentation. The generalization performance of the ELM classifier has not achieved the maximum nearest accuracy of image segmentation. This paper gives a novel technique for WBC detection based on the fast relevance vector machine (Fast-RVM). Firstly, astonishingly sparse relevance vectors (RVs) are obtained while fitting the histogram by RVM. Next, the relevant required threshold value is directly sifted from these limited RVs. Finally, the entire connective WBC regions are segmented from the original image. The proposed method successfully works for WBC detection, and effectively reduces the effects brought about by illumination and staining. To achieve the maximum accuracy of the RVM classifier, we design a search for the best value of the parameters that tune its discriminant function, and upstream by looking for the best subset of features that feed the classifier. Therefore, this proposed RVM method effectively works for WBC detection, and effectively reduces the computational time and preserves the images.

  19. Segment-orientated analysis of two-dimensional strain and strain rate as assessed by velocity vector imaging in patients with acute myocardial infarction

    Directory of Open Access Journals (Sweden)

    Thomas Butz, Corinna N. Lang, Marc van Bracht, Magnus W. Prull, Hakan Yeni, Petra Maagh, Gunnar Plehn, Axel Meissner, Hans-Joachim Trappe

    2011-01-01

    Full Text Available Aims: Strain rate imaging techniques have been proposed for the detection of ischemic or viable myocardium in coronary artery disease, which is still a challenge in clinical cardiology. This retrospective comparative study analyzed regional left ventricular function and scaring with two-dimensional strain (2DS in the first 4 to 10 days after acute anterior myocardial infarction (AMI.Methods and results: The study population consisted of 32 AMI patients with an LAD occlusion and successful reperfusion. The assessment of peak systolic 2DS and peak systolic strain rate (SR was performed segment-oriented with the angle-independent speckle tracking algorithm Velocity Vector Imaging (VVI. The infarcted, adjacent and non-infarcted segments were revealed by late enhancement MRI (LE-MRI, which was used as reference for the comparison with 2DS. The infarcted segments showed a significant decrease of tissue velocities, 2DS and SR in comparison to the non-affected segments.Conclusion: 2DS and SR as assessed by VVI seem to be a suitable approach for echocardiographic quantification of global and regional myocardial function as well as a promising tool for multimodal risk stratification after anterior AMI.

  20. Quantification of resting myocardial blood flow velocity in normal humans using real-time contrast echocardiography. A feasibility study

    Directory of Open Access Journals (Sweden)

    Slordahl Stig

    2005-06-01

    Full Text Available Abstract Background Real-time myocardial contrast echocardiography (MCE is a novel method for assessing myocardial perfusion. The aim of this study was to evaluate the feasibility of a very low-power real-time MCE for quantification of regional resting myocardial blood flow (MBF velocity in normal human myocardium. Methods Twenty study subjects with normal left ventricular (LV wall motion and normal coronary arteries, underwent low-power real-time MCE based on color-coded pulse inversion Doppler. Standard apical LV views were acquired during constant IV. infusion of SonoVue®. Following transient microbubble destruction, the contrast replenishment rate (β, reflecting MBF velocity, was derived by plotting signal intensity vs. time and fitting data to the exponential function; y (t =A (1-e-β(t-t0 + C. Results Quantification was feasible in 82%, 49% and 63% of four-chamber, two-chamber and apical long-axis view segments, respectively. The LAD (left anterior descending artery and RCA (right coronary artery territories could potentially be evaluated in most, but contrast detection in the LCx (left circumflex artery bed was poor. Depending on localisation and which frames to be analysed, mean values of were 0.21–0.69 s-1, with higher values in medial than lateral, and in basal compared to apical regions of scan plane (p = 0.03 and p Conclusion Low-power real-time MCE did have the potential to give contrast enhancement for quantification of resting regional MBF velocity. However, the technique is difficult and subjected to several limitations. Significant variability in β suggests that this parameter is best suited for with-in patient changes, comparing values of stress studies to baseline.

  1. Carbon dioxide induced changes in cerebral blood flow and flow velocity: role of cerebrovascular resistance and effective cerebral perfusion pressure.

    Science.gov (United States)

    Grüne, Frank; Kazmaier, Stephan; Stolker, Robert J; Visser, Gerhard H; Weyland, Andreas

    2015-09-01

    In addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO2-induced changes in CBF, CVR, CPPe, ZFP, and RAP is not fully understood. In a controlled crossover trial, we investigated 10 anesthetized patients aiming at PaCO2 levels of 30, 37, 43, and 50 mm Hg. Cerebral blood flow was measured with a modified Kety-Schmidt-technique. Zero flow pressure and RAP was estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. Effective cerebral perfusion pressure was calculated as the difference between mean arterial pressure and ZFP, CVR as the ratio CPPe/CBF. Statistical analysis was performed by one-way RM-ANOVA. When comparing hypocapnia with hypercapnia, CBF showed a significant exponential reduction by 55% and mean VMCA by 41%. Effective cerebral perfusion pressure linearly decreased by 17% while ZFP increased from 14 to 29 mm Hg. Cerebrovascular resistance increased by 96% and RAP by 39%; despite these concordant changes in mean CVR and Doppler-derived RAP correlation between these variables was weak (r=0.43). In conclusion, under general anesthesia hypocapnia-induced reduction in CBF is caused by both an increase in CVR and a decrease in CPPe, as a consequence of an increase in ZFP.

  2. Compromised cerebrovascular modulation in chronic anxiety: evidence from cerebral blood flow velocity measured by transcranial Doppler sonography

    Institute of Scientific and Technical Information of China (English)

    Hong-Liang Zhang; Zhen-Ni Guo; Ge Yang; Le Yang; Ke Han; Jiang Wu; Yingqi Xing; Yi Yang

    2012-01-01

    Objective Cerebral autoregulation (CA) is the mechanism by which constant cerebral blood flow is maintained despite changes in cerebral perfusion pressure.CA can be evaluated by dynamic monitoring of cerebral blood flow velocity (CBFV) with transcranial Doppler sonography (TCD).The present study aimed to explore CA in chronic anxiety.Methods Subjects with Hamilton anxiety scale scores ≥14 were enrolled and the dynamic changes of CBFV in response to an orthostatic challenge were investigated using TCD.Results In both the anxious and the healthy subjects,the mean CBFV was significantly lower in the upright position than when supine.However,the CBFV changes from supine to upright differed between the anxious and the healthy groups.Anxious subjects showed more pronounced decreases in CBFV with abrupt standing.Conclusion Our results indicate that cerebrovascular modulation is compromised in chronic anxiety; anxious subjects have some insufficiency in maintaining cerebral perfusion after postural change.Given the fact that anxiety and impaired CA are associated with cardiovascular disease,early ascertainment of compromised cerebrovascular modulation using TCD might suggest interventional therapies in the anxious population,and improve the primary prevention of cardiovascular disease.

  3. Abnormality of peripheral nerve conduction velocity associated with illness course, symptoms and fasting blood glucose in patients with type 2 diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Suijing Cui; Jinhua Qiu; Weiliang Luo

    2006-01-01

    BACKGROUND: It has shown that abnormality of peripheral nerve conduction velocity during onset of diabetes mellitus is not related to age and sex, but to symptoms, illness course and level of fasting blood glucose.OBJECTIVE: To measure correlation of abnormality of peripheral nerve conduction velocity with various illness courses, symptoms and levels of fasting blood glucose of patients with type 2 diabetes mellitus.DESIGN: Case analysis.SETTING: Department of Neurology, Central People's Hospital of Huizhou.PARTICIPANTS: A total of 128 patients who were diagnosed as type 2 diabetes mellitus were selected from Central People's Hospital of Huizhou from September 2001 to October 2005. There were 75 males and 53 females aged 32-83 years and the illness course ranged from 1 month to 20 years.METHODS: All 128 patients with type 2 diabetes mellitus received neuro-electrophysiological study and their clinical data were retrospectively analyzed to measure peripheral nerve conduction velocity and fasting blood glucose so as to investigate the correlation of peripheral nerve conduction velocity with clinical symptoms,illness course and levels of fasting blood glucose.MAIN OUTCOME MEASURES: Correlation of peripheral nerve conduction velocity with clinical symptoms, illness course and levels of fasting blood glucose.RESULTS: All 128 patients with type 2 diabetes mellitus were involved in the final analysis. ① Among 128patients, 114 patients had abnormality of peripheral nerve conduction velocity; 110 patients had clinical symptoms, including 102 patients having abnormality of peripheral nerve conduction velocity; 18 patients did not have clinical symptoms, including 12 patients having abnormality of peripheral nerve conduction velocity.There were significant differences between them (x2=8.275, P=0.04). ② Among 128 patients, illness course of 75 patients was equal to or less than 5 years, including 27 patients having abnormality of peripheral nerve conduction velocity

  4. Detection of ventricular suction in an implantable rotary blood pump using support vector machines.

    Science.gov (United States)

    Wang, Yu; Faragallah, George; Divo, Eduardo; Simaan, Marwan A

    2011-01-01

    A new suction detection algorithm for rotary Left Ventricular Assist Devices (LVAD) is presented. The algorithm is based on a Lagrangian Support Vector Machine (LSVM) model. Six suction indices are derived from the LVAD pump flow signal and form the inputs to the LSVM classifier. The LSVM classifier is trained and tested to classify pump flow patterns into three states: No Suction, Approaching Suction, and Suction. The proposed algorithm has been tested using existing in vivo data. When compared to three existing methods, the proposed algorithm produced superior performance in terms of classification accuracy, stability, and learning speed. The ability of the algorithm to detect suction provides a reliable platform in the development of a pump speed controller that has the capability of avoiding suction.

  5. Generation of Patient-Specific induced Pluripotent Stem Cell from Peripheral Blood Mononuclear Cells by Sendai Reprogramming Vectors.

    Science.gov (United States)

    Quintana-Bustamante, Oscar; Segovia, Jose C

    2016-01-01

    Induced pluripotent stem cells (iPSC) technology has changed preclinical research since their generation was described by Shinya Yamanaka in 2006. iPSCs are derived from somatic cells after being reprogrammed back to an embryonic state by specific combination of reprogramming factors. These reprogrammed cells resemble all the characteristic of embryonic stem cells (ESC). The reprogramming technology is even more valuable to research diseases biology and treatment by opening gene and cell therapies in own patient's iPSC. Patient-specific iPSC can be generated from a large variety of patient cells by any of the myriad of reprogramming platforms described. Here, we describe the generation of patient-specific iPSC from patient peripheral blood mononuclear cells by Sendai Reprogramming vectors.

  6. Polymerase chain reaction (PCR) identification of rodent blood meals confirms host sharing by flea vectors of plague.

    Science.gov (United States)

    Franklin, Heather A; Stapp, Paul; Cohen, Amybeth

    2010-12-01

    Elucidating feeding relationships between hosts and parasites remains a significant challenge in studies of the ecology of infectious diseases, especially those involving small or cryptic vectors. Black-tailed prairie dogs (Cynomys ludovicianus) are a species of conservation importance in the North American Great Plains whose populations are extirpated by plague, a flea-vectored, bacterial disease. Using polymerase chain reaction (PCR) assays, we determined that fleas (Oropsylla hirsuta) associated with prairie dogs feed upon northern grasshopper mice (Onychomys leucogaster), a rodent that has been implicated in the transmission and maintenance of plague in prairie-dog colonies. Our results definitively show that grasshopper mice not only share fleas with prairie dogs during plague epizootics, but also provide them with blood meals, offering a mechanism by which the pathogen, Yersinia pestis, may be transmitted between host species and maintained between epizootics. The lack of identifiable host DNA in a significant fraction of engorged Oropsylla hirsuta collected from animals (47%) and prairie-dog burrows (100%) suggests a rapid rate of digestion and feeding that may facilitate disease transmission during epizootics but also complicate efforts to detect feeding on alternative hosts. Combined with other analytical approaches, e.g., stable isotope analysis, molecular genetic techniques can provide novel insights into host-parasite feeding relationships and improve our understanding of the role of alternative hosts in the transmission and maintenance of disease.

  7. Optimization of lentiviral vector transduction into peripheral blood mononuclear cells in combination with the fibronectin fragment CH-296 stimulation.

    Science.gov (United States)

    Chono, Hideto; Goto, Yumi; Yamakawa, Satoko; Tanaka, Shinya; Tosaka, Yasuhiro; Nukaya, Ikuei; Mineno, Junichi

    2011-03-01

    Large scale T-cell expansion and efficient gene transduction are required for adoptive T-cell gene therapy. Based on our previous observations, human peripheral blood mononuclear cells (PBMCs) can be expanded efficiently while conserving a naïve phenotype by stimulating with both recombinant human fibronectin fragment (CH-296) and anti-CD3 monoclonal antibodies. In this article, we explored the possibility of using this co-stimulation method to generate engineered T cells using lentiviral vector. Human PBMCs were stimulated with anti-CD3 together with immobilized CH-296 or anti-CD28 antibody as well as anti-CD3/anti-CD28 conjugated beads and transduced with lentiviral vector simultaneously. Co-stimulation with CH-296 gave superior transduction efficiency than with anti-CD28. Next, PBMCs were stimulated and transduced with anti-CD3/CH-296 or with anti-CD3/CD28 beads. T-cell expansion, gene transfer efficiencies and immunophenotypes were analysed. Stimulation with anti-CD3/CH-296 resulted in more than 10-times higher cell expansion and higher gene transfer efficiency with conservation of the naïve phenotype compared with anti-CD3/CD28 stimulation method. Thus, lentiviral transduction with anti-CD3/CH-296 co-stimulation is an efficient way to generate large numbers of genetically modified T cells and may be suitable for many gene therapy protocols that use adoptive T-cell transfer therapy.

  8. Automatic Recognition of Acute Myelogenous Leukemia in Blood Microscopic Images Using K-means Clustering and Support Vector Machine.

    Science.gov (United States)

    Kazemi, Fatemeh; Najafabadi, Tooraj Abbasian; Araabi, Babak Nadjar

    2016-01-01

    Acute myelogenous leukemia (AML) is a subtype of acute leukemia, which is characterized by the accumulation of myeloid blasts in the bone marrow. Careful microscopic examination of stained blood smear or bone marrow aspirate is still the most significant diagnostic methodology for initial AML screening and considered as the first step toward diagnosis. It is time-consuming and due to the elusive nature of the signs and symptoms of AML; wrong diagnosis may occur by pathologists. Therefore, the need for automation of leukemia detection has arisen. In this paper, an automatic technique for identification and detection of AML and its prevalent subtypes, i.e., M2-M5 is presented. At first, microscopic images are acquired from blood smears of patients with AML and normal cases. After applying image preprocessing, color segmentation strategy is applied for segmenting white blood cells from other blood components and then discriminative features, i.e., irregularity, nucleus-cytoplasm ratio, Hausdorff dimension, shape, color, and texture features are extracted from the entire nucleus in the whole images containing multiple nuclei. Images are classified to cancerous and noncancerous images by binary support vector machine (SVM) classifier with 10-fold cross validation technique. Classifier performance is evaluated by three parameters, i.e., sensitivity, specificity, and accuracy. Cancerous images are also classified into their prevalent subtypes by multi-SVM classifier. The results show that the proposed algorithm has achieved an acceptable performance for diagnosis of AML and its common subtypes. Therefore, it can be used as an assistant diagnostic tool for pathologists.

  9. In vitro confocal micro-PIV measurements of blood flow in a square microchannel: the effect of the haematocrit on instantaneous velocity profiles.

    Science.gov (United States)

    Lima, Rui; Wada, Shigeo; Takeda, Motohiro; Tsubota, Ken-ichi; Yamaguchi, Takami

    2007-01-01

    A confocal microparticle image velocimetry (micro-PIV) system was used to obtain detailed information on the velocity profiles for the flow of pure water (PW) and in vitro blood (haematocrit up to 17%) in a 100-microm-square microchannel. All the measurements were made in the middle plane of the microchannel at a constant flow rate and low Reynolds number (Re=0.025). The averaged ensemble velocity profiles were found to be markedly parabolic for all the working fluids studied. When comparing the instantaneous velocity profiles of the three fluids, our results indicated that the profile shape depended on the haematocrit. Our confocal micro-PIV measurements demonstrate that the root mean square (RMS) values increase with the haematocrit implying that it is important to consider the information provided by the instantaneous velocity fields, even at low Re. The present study also examines the potential effect of the RBCs on the accuracy of the instantaneous velocity measurements.

  10. The Effects of Chinese Medicines on Micro-circulation of Nail Folds and Blood Flow Velocity of Limbs in the Patients with Arteriosclerotic Obliteration

    Institute of Scientific and Technical Information of China (English)

    葛辛; 葛芃; 彭玉清; 陈云翔

    2003-01-01

    The effects of Chinese medicines on micro-circulation and blood flow velocity in arteries of the lower limbs were observed in 33 patients with arteriosclerotic obliteration (ASO). The results showed that the integral values of micro-circulation after treatment were obviously higher than those before treatment (P<0.05 or P<0.01). Blood flow velocity in arteries of the lower limbs determined with the color Doppler ultrasound detecting method after treatment were also obviously higher than those before treatment (P<0.05 or P<0.01). In this series of 33 ASO patients, the markedly effective rate was 36.36%, and the total effective rate was 63.64%. The observation indicates that the recipe prescribed according to the principle of supplementing qi and activating blood circulation can effectively improve micro-circulation in ASO patients, and accelerate blood flow in arteries of the lower limbs.

  11. Rotations with Rodrigues' Vector

    Science.gov (United States)

    Pina, E.

    2011-01-01

    The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…

  12. Interstellar neutral helium in the heliosphere from IBEX observations. III. Mach number of the flow, velocity vector, and temperature from the first six years of measurements

    CERN Document Server

    Bzowski, M; Kubiak, M A; Sokol, J M; Fuselier, S A; Galli, A; Heirtzler, D; Kucharek, H; Leonard, T W; McComas, D J; Moebius, E; Schwadron, N A; Wurz, P

    2015-01-01

    We analyzed observations of interstellar neutral helium (ISN~He) obtained from the Interstellar Boundary Explorer (IBEX) satellite during its first six years of operation. We used a refined version of the ISN~He simulation model, presented in the companion paper by Sokol_et al. 2015, and a sophisticated data correlation and uncertainty system and parameter fitting method, described in the companion paper by Swaczyna et al 2015. We analyzed the entire data set together and the yearly subsets, and found the temperature and velocity vector of ISN~He in front of the heliosphere. As seen in the previous studies, the allowable parameters are highly correlated and form a four-dimensional tube in the parameter space. The inflow longitudes obtained from the yearly data subsets show a spread of ~6 degree, with the other parameters varying accordingly along the parameter tube, and the minimum chi-square value is larger than expected. We found, however, that the Mach number of the ISN~He flow shows very little scatter an...

  13. Changes of balance between proteinase and their inhibitors in blood of pigs with high-velocity missile wounds

    Institute of Scientific and Technical Information of China (English)

    周元国; 朱佩芳; 周继红; 李晓炎

    2003-01-01

    Objective: To study the effect of imbalance between lysosomal enzymes and their inhibitors in blood on disturbance of the local and whole body after trauma. Methods: The dynamic changes of lysosomal enzymes and proteinase inhibitors were studied in 12 pigs with femoral comminuted fractures in both hind limbs caused by high velocity missiles. Four normal pigs served as controls. Results: After injury, the activity of Cathepsin D in arterial plasma increased gradually and reached the highest level at 8 hours, acid phosphatase in serum began to increase at 12 hours and the value of serum elastase did not change significantly. The level of α1-antitrypsin, a proteinase inhibitor in plasma, decreased significantly in the early stage after injury [73.5%±6.4% and 81.0%±5.1% of the baseline value (1.67 μmol*ml-1*min-1± 0.29 μmol*ml-1*min-1) at l and 2 hours after injury, respectively, P<0.05], then increased gradually and was higher than the baseline value at 12 hours after injury. Conclusions: Imbalance between lysosomal enzymes and proteinase inhibitors occurs soon after injury, which might result in continuous tissue damage and play an important role in the disturbance of general reaction after injury.

  14. Red blood cell phase separation in symmetric and asymmetric microchannel networks: effect of capillary dilation and inflow velocity

    Science.gov (United States)

    Clavica, Francesco; Homsy, Alexandra; Jeandupeux, Laure; Obrist, Dominik

    2016-11-01

    The non-uniform partitioning or phase separation of red blood cells (RBCs) at a diverging bifurcation of a microvascular network is responsible for RBC heterogeneity within the network. The mechanisms controlling RBC heterogeneity are not yet fully understood and there is a need to improve the basic understanding of the phase separation phenomenon. In this context, in vitro experiments can fill the gap between existing in vivo and in silico models as they provide better controllability than in vivo experiments without mathematical idealizations or simplifications inherent to in silico models. In this study, we fabricated simple models of symmetric/asymmetric microvascular networks; we provided quantitative data on the RBC velocity, line density and flux in the daughter branches. In general our results confirmed the tendency of RBCs to enter the daughter branch with higher flow rate (Zweifach-Fung effect); in some cases even inversion of the Zweifach-Fung effect was observed. We showed for the first time a reduction of the Zweifach-Fung effect with increasing flow rate. Moreover capillary dilation was shown to cause an increase of RBC line density and RBC residence time within the dilated capillary underlining the possible role of pericytes in regulating the oxygen supply.

  15. Comparison of cerebral blood flow velocity estimation with cranial ultrasound imaging for early prediction of outcome in preterm infants.

    Science.gov (United States)

    Rennie, J M; Coughtrey, H; Morley, R; Evans, D H

    1995-01-01

    Seventy-four low birth weight infants underwent serial measurements of cerebral blood flow velocity (CBFV) using Doppler ultrasound together with ultrasound imaging of the brain. Surviving infants were examined and assessed using the Bayley scales of mental and motor development at 18 months post-term. There were no significant differences in mean CBFV between normal and impaired infants. Infants with abnormal neurological signs (n = 6) or developmental delay (n = 3) did not show the usual steady rise in CBFV during the first few days of life. Four of nine had a rise, then a fall in CBFV compared with 4 of 31 with complete data in the normal group. This difference is significant (chi 2 = 4.3, p = 0.03). The magnitude of the percentage increase between day 1 and day 3 was also smaller in the abnormal group (median 0% vs. 39%, Mann-Whitney p = 0.03). A structural abnormality seen on the cranial ultrasound image was a better predictor of adverse outcome than an abnormal CBFV pattern, with a better sensitivity and specificity (66% and 97% for imaging compared to 44% and 87% for CBFV). The addition of serial ultrasound Doppler measurements of CBFV did not improve the prediction of outcome obtained using ultrasound imaging alone.

  16. Ultrasound Vector Flow Imaging: Part I: Sequential Systems

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav Ivanov; Yu, Alfred C. H.;

    2016-01-01

    The paper gives a review of the most important methods for blood velocity vector flow imaging (VFI) for conventional, sequential data acquisition. This includes multibeam methods, speckle tracking, transverse oscillation, color flow mapping derived vector flow imaging, directional beamforming......, and variants of these. The review covers both 2-D and 3-D velocity estimation and gives a historical perspective on the development along with a summary of various vector flow visualization algorithms. The current state-of-the-art is explained along with an overview of clinical studies conducted and methods...

  17. Oral Levosimendan Increases Cerebral Blood Flow Velocities in Patients with a History of Stroke or Transient Ischemic Attack: A Pilot Safety Study

    Directory of Open Access Journals (Sweden)

    Matti Kivikko, MD, PhD

    2015-12-01

    Conclusions: Oral levosimendan increases cerebral blood flow velocities and diminishes NT-pro-BNP levels in patients with earlier ischemic cerebrovascular event. Daily doses up to 1.0 mg were well tolerated, whereas the 2.0 mg dose level induced an increase in ventricular extrasystoles. ClinicalTrials.gov identifier: NCT00698763.

  18. Quantification of left ventricular mechanics using vector-velocity imaging, a novel feature tracking algorithm, applied to echocardiography and cardiac magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    LI Peng; MENG Hong; LIU Shi-zhen; Mani A Vannan

    2012-01-01

    Background Tagged magnetic resonance imaging (MRI) is the non-invasive golden standard to measure myocardial deformity.Tissue Doppler Imaging can be used to assess myocardial deformity,however,it has the limitation of angle-dependence.Our study aimed to compare left ventricular torsion and strains measured by velocity-vector imaging (VVI) using echocardiography (echo-VVI) and MRI (MRI-VVI),and to validate them against harmonic phase tagged MRI (HARP MRI).Methods A total number of 34 subjects (14 normal and 20 patients) were evaluated.Apical and basal image of left ventricular short axis view were acquired for measurements of apical and basal rotation.circumferential and radial strain using both echo-VVI and MRI-VVl.An apical four-chamber view was obtained for measuring the distance between the apical and basal levels.Results The correlations of segmental rotations,circumferential and radial strains were high between echo-VVI and HARP MRI,while the agreement of apical rotation was poor.Left ventricular torsion showed much better correlation and agreement between echo-VVI and HARP MRI than apical rotation:the coefficient was 0.97,P <0.001.The correlation between MRI-VVI and HARP MRI in quantifying rotational parameters and strains was similar with echo-VVI and HARP MRI.Echo-VVI could discriminate normal and dysfunctional ventricles on either hypertensive or dilated cardiomyopathy.Conclusion The data from this study show that (1) it is feasible to quantify left ventricular torsion and myocardial strain using echo-VVI and MRI-VVI in normal subjects,patients with left ventricular global systolic dysfunction and segment systolic dysfunction; (2) the agreement among all mechanical parameters derived from echo-VVl,MRI-VVI,and HARP MRI remained with clinically acceptable ranges.

  19. Three-dimensional flow vectors from rf ultrasound signals

    Science.gov (United States)

    Tuthill, Theresa A.; Rubin, Jonathan M.; Fowlkes, J. B.

    2002-04-01

    A new ultrasound technique for determining three-dimensional velocity vectors has been devised using radio frequency (RF) data from commercially available scanners. Applied to blood flow, this technique could prove useful for evaluating hemodynamics and detecting stenoses. Three orthogonal velocity vectors are computed from the RF signals of two steered beams from a single array. The in-plane velocities are determined using standard Doppler analysis, while the out-of-plane component is derived from the total velocity as computed from temporal decorrelation and the in-plane components. The technique was tested using contrast agent pumped through a flow tube. A GE Vingmed SystemV scanner with a 10 MHz linear array provided scans at beam steering angles of +/- 20 degree(s). Both Doppler velocities and temporal complex decorrelation were computed for each digitized voxel. Additional studies were done on a blood mimicking fluid and in vivo with a canine femoral artery. Vector plots were constructed to show flow for various transducer angles. Angle estimates were within 20 degree(s), and the mean error for the velocity amplitude was less than 15%. The in vivo results provided velocity estimates consistent with the literature. The proposed method, unlike current Doppler velocity measurement techniques, provides quantitative velocity information independent of transducer orientation.

  20. Imaging blood’s velocity using synthetic aperture ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Li, Ye

    2012-01-01

    The blood velocity vector can be estimated using synthetic aperture techniques in medical ultrasound by using short emission sequences. The whole image region is insonified and the flow can be tracked in all directions continuously. This is a major advantage compared to commercial systems, since...

  1. 3-D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Holbek, Simon

    studies and in vivo. Phantom measurements are compared with their corresponding reference value, whereas the in vivo measurement is validated against the current golden standard for non-invasive blood velocity estimates, based on magnetic resonance imaging (MRI). The study concludes, that a high precision......, if this significant reduction in the element count can still provide precise and robust 3-D vector flow estimates in a plane. The study concludes that the RC array is capable of estimating precise 3-D vector flow both in a plane and in a volume, despite the low channel count. However, some inherent new challenges......For the last decade, the field of ultrasonic vector flow imaging has gotten an increasingly attention, as the technique offers a variety of new applications for screening and diagnostics of cardiovascular pathologies. The main purpose of this PhD project was therefore to advance the field of 3-D...

  2. A segmented K-space velocity mapping protocol for quantification of renal artery blood flow during breath-holding

    DEFF Research Database (Denmark)

    Thomsen, C; Cortsen, M; Söndergaard, L;

    1995-01-01

    for renal artery flow determination. The protocol uses 16 phase-encoding lines per heart beat during 16 heart cycles and gives a temporal velocity resolution of 160 msec. Comparison with a conventional ECG-triggered velocity mapping protocol was made in phantoms as well as in volunteers. In our study, both...

  3. Influence of Acute Jugular Vein Compression on the Cerebral Blood Flow Velocity, Pial Artery Pulsation and Width of Subarachnoid Space in Humans

    OpenAIRE

    Frydrychowski, Andrzej F.; Pawel J Winklewski; Wojciech Guminski

    2012-01-01

    PURPOSE: The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1) pial artery pulsation (cc-TQ); (2) cerebral blood flow velocity (CBFV); (3) peripheral blood pressure; and (4) possible relations between mentioned parameters. METHODS: Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ) were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS), CBFV i...

  4. High Frame Rate Synthetic Aperture 3D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Holbek, Simon; Stuart, Matthias Bo

    2016-01-01

    3-D blood flow quantification with high spatial and temporal resolution would strongly benefit clinical research on cardiovascular pathologies. Ultrasonic velocity techniques are known for their ability to measure blood flow with high precision at high spatial and temporal resolution. However......, current volumetric ultrasonic flow methods are limited to one velocity component or restricted to a reduced field of view (FOV), e.g. fixed imaging planes, in exchange for higher temporal resolutions. To solve these problems, a previously proposed accurate 2-D high frame rate vector flow imaging (VFI......) technique is extended to estimate the 3-D velocity components inside a volume at high temporal resolutions (

  5. A Robust System for Longitudinal Knee Joint Edema and Blood Flow Assessment Based on Vector Bioimpedance Measurements.

    Science.gov (United States)

    Hersek, Sinan; Töreyin, Hakan; Inan, Omer T

    2016-06-01

    We present a robust vector bioimpedance measurement system for longitudinal knee joint health assessment, capable of acquiring high resolution static (slowly varying over the course of hours to days) and dynamic (rapidly varying on the order of milli-seconds) bioresistance and bioreactance signals. Occupying an area of 78×90 mm(2) and consuming 0.25 W when supplied with ±5 V, the front-end achieves a dynamic range of 345 Ω and noise floor of 0.018 mΩrms (resistive) and 0.055 mΩrms (reactive) within a bandwidth of 0.1-20 Hz. A microcontroller allows real-time calibration to minimize errors due to environmental variability (e.g., temperature) that can be experienced outside of lab environments, and enables data storage on a micro secure digital card. The acquired signals are then processed using customized physiology-driven algorithms to extract musculoskeletal (edema) and cardiovascular (local blood volume pulse) features from the knee joint. In a feasibility study, we found statistically significant differences between the injured and contralateral static knee impedance measures for two subjects with recent unilateral knee injury compared to seven controls. Specifically, the impedance was lower for the injured knees, supporting the physiological expectations for increased edema and damaged cell membranes. In a second feasibility study, we demonstrate the sensitivity of the dynamic impedance measures with a cold-pressor test, with a 20 mΩ decrease in the pulsatile resistance associated with increased downstream peripheral vascular resistance. The proposed system will serve as a foundation for future efforts aimed at quantifying joint health status continuously during normal daily life.

  6. Relationship of CHA2DS2-VASc and CHADS2 score to left atrial remodeling detected by velocity vector imaging in patients with atrial fibrillation.

    Directory of Open Access Journals (Sweden)

    Yihui Li

    Full Text Available BACKGROUND: The CHADS2/CHA2DS2-VASc scores are used to predict thrombo-embolic/stroke in patients with nonvalvular atrial fibrillation (AF. Nevertheless, limited data are available regarding the association between these risk stratification for stroke and left atrial (LA remodeling status of AF patients. The purpose of this study was to explore the association between these scores and LA remodeling status assessed quantificationally by echocardiography in AF patients. METHODS: One hundred AF patients were divided into 3 groups based on the CHA2DS2-VASc/CHADS2 score: the score of 0 (low stroke risk, the score of 1 (moderate stroke risk and the score of ≥2 (high stroke risk. All patients were performed through conventional and velocity vector imaging echocardiography. Echocardiographic parameters: maximum LA volume index (LAVImax, LA total emptying fraction (LAEFt and LA mean strain were obtained to assess quantificationally LA remodeling status. RESULTS: On categorizing with CHA2DS2-VASc, the score of 1 group showed augment in LAVImax and attenuation in LA mean strain derived from VVI, compared with the score of 0 group (LAVImax: 40.27±21.91 vs. 26.79±7.87, p=0.002; LA mean strain: 15.18±6.36 vs. 22±8.54, p=0.001. On categorizing with the CHADS2 score, similar trends were seen between the score of ≥2 and 1 groups (LAVImax: 43.72±13.77 vs. 31.41±9.50, p<0.001; LA mean strain: 11.01±5.31 vs. 18.63±7.00, p<0.001. With multivariate logistic regression, LAVImax (odds ratio: 0.92 , 95% C=I: 0.85 to 0.98, p= 0.01 and LA mean strain reflecting LA remodeling (odds ratio: 1.10, 95% CI: 1.02 to 1.19, p=0.01 were strongly predictive of the CHA2DS2-VASc score of 0. CONCLUSIONS: The superiority of the CHADS2 score may lay in identifying LA remodeling of AF patients with high stroke risk. Whereas, the CHA2DS2-VASc score was better than the CHADS2 score at identifying LA remodeling of AF patients presenting low stroke risk.

  7. Microwave Ablation Using Four-Tine Antenna: Effects of Blood Flow Velocity, Vessel Location, and Total Displacement on Porous Hepatic Cancer Tissue

    Directory of Open Access Journals (Sweden)

    Montree Chaichanyut

    2016-01-01

    Full Text Available This research is concerned with microwave ablation analyses using a 2.45 GHz four-tine (4T antenna for hepatic cancer tissue. In the study, three-dimensional finite-element models were utilized to examine the tissue temperature distributions during and after MW ablation. A preliminary study was first carried out with regard to the specific absorption rates along the 4T antenna insertion depths and the temperature distributions inside the solid and porous liver models with either 3 cm-in-diameter tumor or 5 cm-in-diameter tumor. Based on the preliminary results, the porous models were further examined for the effect of varying blood flow velocities (0–200 cm/s with a 1 cm-in-diameter blood vessel next to the antenna and also for the effect of vessel-antenna locations (0, 0.8, and 1.3 cm with a constant blood flow velocity of 16.7 cm/s. All scenarios were simulated under temperature-controlled mode (90°C. The findings revealed that the blood flow velocity and vessel location influence the ablation effectiveness and that increased blood flow inhibits heat transfer to the vessel wall. At the nearest and farthest vessel-antenna locations (0 and 1.3 cm, approximately 90.3% and 99.55% of the cancer cells were eradicated except for the areas adjacent to the vessel. In addition, total tissue thermal displacement is 5.9 mm which is 6.59% of the total length of the overall model.

  8. Microwave Ablation Using Four-Tine Antenna: Effects of Blood Flow Velocity, Vessel Location, and Total Displacement on Porous Hepatic Cancer Tissue

    Science.gov (United States)

    Chaichanyut, Montree

    2016-01-01

    This research is concerned with microwave ablation analyses using a 2.45 GHz four-tine (4T) antenna for hepatic cancer tissue. In the study, three-dimensional finite-element models were utilized to examine the tissue temperature distributions during and after MW ablation. A preliminary study was first carried out with regard to the specific absorption rates along the 4T antenna insertion depths and the temperature distributions inside the solid and porous liver models with either 3 cm-in-diameter tumor or 5 cm-in-diameter tumor. Based on the preliminary results, the porous models were further examined for the effect of varying blood flow velocities (0–200 cm/s) with a 1 cm-in-diameter blood vessel next to the antenna and also for the effect of vessel-antenna locations (0, 0.8, and 1.3 cm) with a constant blood flow velocity of 16.7 cm/s. All scenarios were simulated under temperature-controlled mode (90°C). The findings revealed that the blood flow velocity and vessel location influence the ablation effectiveness and that increased blood flow inhibits heat transfer to the vessel wall. At the nearest and farthest vessel-antenna locations (0 and 1.3 cm), approximately 90.3% and 99.55% of the cancer cells were eradicated except for the areas adjacent to the vessel. In addition, total tissue thermal displacement is 5.9 mm which is 6.59% of the total length of the overall model. PMID:27642364

  9. Effect of sequential pneumatic compression therapy on venous blood velocity, refilling time, pain and quality of life in women with varicose veins: a randomized control study.

    Science.gov (United States)

    Yamany, Abeer; Hamdy, Bassant

    2016-07-01

    [Purpose] The aim of this study was to investigate the effects of sequential pneumatic compression therapy on venous blood flow, refilling time, pain level, and quality of life in women with varicose veins. [Subjects and Methods] Twenty-eight females with varicose veins were selected and randomly allocated to a control group, and experimental group. Maximum and mean venous blood velocities, the refilling time, pain by visual analog scale and quality of life by Aberdeen Varicose Veins Questionnaire were measured in all patients before and after six weeks of treatment. Both groups received lower extremity exercises; in addition, patients in the experimental group received sequential pneumatic compression therapy for 30 minutes daily, five days a week for six weeks. [Results] All measured parameters improved significantly in both groups, comparison of post treatment measurements between groups showed that the maximum and mean blood flow velocity, the pain level, and quality of life were significantly higher in the experimental group compared with the control group. On the other hand there was no significant difference between groups for refilling time. [Conclusion] Sequential pneumatic compression therapy with the applied parameters was an effective modality for increasing venous blood flow, reducing pain, and improving quality of women life with varicose veins.

  10. Vector velocimeter

    DEFF Research Database (Denmark)

    2012-01-01

    for generation of a reference beam, a detector system comprising a first detector arrangement arranged in such a way that the signal beam and the reference beam are incident upon the first detector arrangement with the reference beam propagating at an angle relative to a signal beam, and wherein the first......The present invention relates to a compact, reliable and low-cost vector velocimeter for example for determining velocities of particles suspended in a gas or fluid flow, or for determining velocity, displacement, rotation, or vibration of a solid surface, the vector velocimeter comprising a laser...... assembly for emission of a measurement beam for illumination of an object in a measurement volume with coherent light whereby a signal beam emanating from the object in the measurement volume is formed in response to illumination of the object by the measurement beam, a reference beam generator...

  11. Transcutaneous measurement of volume blood flow

    Science.gov (United States)

    Daigle, R. E.; Mcleod, F. D.; Miller, C. W.; Histand, M. B.; Wells, M. K.

    1974-01-01

    Blood flow velocity measurements, using Doppler velocimeter, are described. The ability to measure blood velocity using ultrasound is derived from the Doppler effect; the change in frequency which occurs when sound is reflected or transmitted from a moving target. When ultrasound of the appropriate frequency is transmitted through a moving blood stream, the blood cells act as point scatterers of ultrasonic energy. If this scattered ultrasonic energy is detected, it is found to be shifted in frequency according to the velocity of the blood cells, nu, the frequency of the incident sound, f sub o, the speed of sound in the medium, c, and the angle between the sound beam and the velocity vector, o. The relation describing this effect is known as the Doppler equation. Delta f = 2 f sub o x nu x cos alpha/c. The theoretical and experimental methods are evaluated.

  12. Recombinant viral-vectored vaccines expressing Plasmodium chabaudi AS apical membrane antigen 1: mechanisms of vaccine-induced blood-stage protection.

    Science.gov (United States)

    Biswas, Sumi; Spencer, Alexandra J; Forbes, Emily K; Gilbert, Sarah C; Holder, Anthony A; Hill, Adrian V S; Draper, Simon J

    2012-05-15

    Apical membrane Ag 1 (AMA1) is one of the leading candidate Ags for inclusion in a subunit vaccine against blood-stage malaria. However, the efficacy of Ab-inducing recombinant AMA1 protein vaccines in phase IIa/b clinical trials remains disappointing. In this article, we describe the development of recombinant human adenovirus serotype 5 and modified vaccinia virus Ankara vectors encoding AMA1 from the Plasmodium chabaudi chabaudi strain AS. These vectors, when used in a heterologous prime-boost regimen in BALB/c mice, are capable of inducing strong transgene-specific humoral and cellular immune responses. We show that this vaccination regimen is protective against a nonlethal P. chabaudi chabaudi strain AS blood-stage challenge, resulting in reduced peak parasitemias. The role of vaccine-induced, AMA1-specific Abs and T cells in mediating the antiparasite effect was investigated by in vivo depletion of CD4(+) T cells and adoptive-transfer studies into naive and immunodeficient mice. Depletion of CD4(+) T cells led to a loss of vaccine-induced protection. Adoptive-transfer studies confirmed that efficacy is mediated by both CD4(+) T cells and Abs functioning in the context of an intact immune system. Unlike previous studies, these results confirm that Ag-specific CD4(+) T cells, induced by a clinically relevant vaccine-delivery platform, can make a significant contribution to vaccine blood-stage efficacy in the P. chabaudi model. Given that cell-mediated immunity may also contribute to parasite control in human malaria, these data support the clinical development of viral-vectored vaccines that induce both T cell and Abs against Plasmodium falciparum blood-stage malaria Ags like AMA1.

  13. Support vector machines as multivariate calibration model for prediction of blood glucose concentration using a new non-invasive optical method named Pulse Glucometry.

    Science.gov (United States)

    Ogawa, Mitsuhiro; Yamakoshi, Yasuhiro; Satoh, Makoto; Nogawa, Masamichi; Yamakoshi, Takehiro; Tanaka, Shinobu; Rolfe, Peter; Tamura, Toshiyo; Yamakoshi, Ken-ichi

    2007-01-01

    A novel optical non-invasive in vivo blood glucose concentration (BGL) measurement technique, named "Pulse Glucometry", was combined with a kernel method; support vector machines. The total transmitted radiation intensity (I lambda) and the cardiac-related pulsatile changes superimposed on I lambda in human adult fingertips were measured over the wavelength range from 900 to 1700 nm using a very fast spectrophotometer, obtaining a differential optical density (delta OD lambda) related to the blood component in the finger tissues. Subsequently, a calibration model using paired data of a family of delta OD lambda s and the corresponding known BGLs was constructed with support vector machines regression instead of using calibration by a conventional partial least squares regression (PLS). Our results show that the calibration model based on the support vector machines can provide a good regression for the 183 paired data, in which the BGLs ranged from 89.0-219 mg/dl (4.94-12.2 mmol/l). The resultant regression was evaluated by the Clarke error grid analysis and all data points fell within the clinically acceptable regions (region A: 93%, region B: 7%).

  14. Efficient focusing scheme for transverse velocity estimation using cross-correlation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2001-01-01

    The blood velocity can be estimated by cross-correlation of received RE signals, but only the velocity component along the beam direction is found. A previous paper showed that the complete velocity vector can be estimated, if received signals are focused along lines parallel to the direction...... simulations with Field II. A 64-elements, 5 MHz linear array was used. A parabolic velocity profile with a peak velocity of 0.5 m/s was considered for different angles between the flow and the ultrasound beam and for different emit foci. At 60 degrees the relative standard deviation was 0.58 % for a transmit...

  15. Enhanced Generation of Integration-free iPSCs from Human Adult Peripheral Blood Mononuclear Cells with an Optimal Combination of Episomal Vectors.

    Science.gov (United States)

    Wen, Wei; Zhang, Jian-Ping; Xu, Jing; Su, Ruijun Jeanna; Neises, Amanda; Ji, Guang-Zhen; Yuan, Weiping; Cheng, Tao; Zhang, Xiao-Bing

    2016-06-14

    We previously reported the generation of integration-free induced pluripotent stem cells from adult peripheral blood (PB) with an improved episomal vector (EV) system, which uses the spleen focus-forming virus U3 promoter and an extra factor BCL-XL (B). Here we show an ∼100-fold increase in efficiency by optimizing the vector combination. The two most critical factors are: (1) equimolar expression of OCT4 (O) and SOX2 (S), by using a 2A linker; (2) a higher and gradual increase in the MYC (M) to KLF4 (K) ratio during the course of reprogramming, by using two individual vectors to express M and K instead of one. The combination of EV plasmids (OS + M + K + B) is comparable with Sendai virus in reprogramming efficiency but at a fraction of the cost. The generated iPSCs are indistinguishable from those from our previous approach in pluripotency and phenotype. This improvement lays the foundation for broad applications of episomal vectors in PB reprogramming.

  16. Enhanced Generation of Integration-free iPSCs from Human Adult Peripheral Blood Mononuclear Cells with an Optimal Combination of Episomal Vectors

    Directory of Open Access Journals (Sweden)

    Wei Wen

    2016-06-01

    Full Text Available We previously reported the generation of integration-free induced pluripotent stem cells from adult peripheral blood (PB with an improved episomal vector (EV system, which uses the spleen focus-forming virus U3 promoter and an extra factor BCL-XL (B. Here we show an ∼100-fold increase in efficiency by optimizing the vector combination. The two most critical factors are: (1 equimolar expression of OCT4 (O and SOX2 (S, by using a 2A linker; (2 a higher and gradual increase in the MYC (M to KLF4 (K ratio during the course of reprogramming, by using two individual vectors to express M and K instead of one. The combination of EV plasmids (OS + M + K + B is comparable with Sendai virus in reprogramming efficiency but at a fraction of the cost. The generated iPSCs are indistinguishable from those from our previous approach in pluripotency and phenotype. This improvement lays the foundation for broad applications of episomal vectors in PB reprogramming.

  17. Absolute Geostrophic Velocity Inverted from the Polar Science Center Hydrographic Climatology (PHC3.0) of the Arctic Ocean with the P-Vector Method (NCEI Accession 0156425)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset (called PHC-V) comprises 3D gridded climatological fields of absolute geostrophic velocity of the Arctic Ocean inverted from the Polar science center...

  18. Synoptic Monthly Gridded WOD Absolute Geostrophic Velocity (SMG-WOD-V) (January 1945 - December 2014) with the P-Vector Method (NCEI Accession 0146195)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SMG-WOD-V dataset comprises synoptic monthly global gridded fields of absolute geostrophic velocity inverted from the synoptic monthly gridded WOD temperature...

  19. The phosphodiesterase 5 inhibitor sildenafil has no effect on cerebral blood flow or blood velocity, but nevertheless induces headache in healthy subjects

    DEFF Research Database (Denmark)

    Kruuse, Christina; Thomsen, Lars Lykke; Jacobsen, Torsten Bjørn

    2002-01-01

    , and regional cerebral blood flow in the perfusion area of the middle cerebral artery (rCBFmca) was measured using single photon emission computed tomography and xenon inhalation. Radial and temporal artery diameters were studied using high-frequency ultrasound. Blood pressure and heart rate were recorded......Cyclic nucleotides are important hemodynamic regulators in many tissues. Glyceryl trinitrate markedly dilates large cerebral arteries and increases cGMP. Here, the authors study the effect of sildenafil, a selective inhibitor of cGMP-hydrolyzing phosphodiesterase 5 on cerebral hemodynamics...

  20. The association of 25(OH)D with blood pressure, pulse pressure and carotid–radial pulse wave velocity in African women

    OpenAIRE

    Iolanthé M Kruger; Schutte, Aletta E.; Huisman, Hugo W.; Van Rooyen, Johannes M.; Schutte, Rudolph; Malan, Leoné; Malan, Nicolaas T.; Carla M T Fourie; Kruger, Annamarie

    2013-01-01

    High susceptibility of the African population to develop cardiovascular disease obliges us to investigate possible contributing risk factors. Our aim was to determine whether low 25(OH)D status is associated with increased blood pressure and carotid-radial pulse wave velocity in black South African women. We studied 291 urban women (mean age: 57.5669.00 yrs.). 25(OH)D status was determined by serum 25(OH)D levels. Women were stratified into sufficient (.30 ng/ ml), and insufficien...

  1. Open loop control of an induction motor's velocity using PWM with space vectors; Control en lazo abierto de la velocidad de un motor de induccion utilizando PWM con vectores espaciales

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Lopez, Manuel

    2001-10-15

    This work describes the design and implementation of an open loop speed controller for an induction motor. This controller is based on a DSP TMS320F240 chip from Texas Instruments. Speed control is achieved by maintaining the magnetic flux constant through the regularization of stator voltage/frequency relationship. Voltage and frequency variation are achieved using the strategy of pulse width modulation with space vectors. Hardware design is presented (current source and the printed circuit for the intelligent power module) and the software (control algorithms and the modulation strategy using space vectors). The algorithms given were implement using the TMS320F240 language. [Spanish] Este trabajo describe el diseno y la implementacion de un control de la velocidad en lazo abierto de un motor de induccion, basado en el DSP TMS320F240 de Texas Instruments. El control de la velocidad se logra manteniendo el flujo en el entre hierro constante, lo cual es realizado al regular el valor de la relacion voltaje/frecuencia en el estator. La variacion del voltaje y la frecuencia se realiza utilizando la estrategia de modulacion del ancho de los pulsos con vectores espaciales. Se presenta el diseno de los circuitos (fuente de corriente continua y circuito impreso para el modulo inteligente de potencia) y de los programas (algoritmos de control y de la estrategia de modulacion con vectores espaciales) necesarios que se utilizaron durante la implementacion del accionamiento del motor. Los algoritmos dados fueron implementados en el lenguaje ensamblador del TMS320F240.

  2. An Impact Velocity Device Design for Blood Spatter Pattern Generation with Considerations for High-Speed Video Analysis.

    Science.gov (United States)

    Stotesbury, Theresa; Illes, Mike; Vreugdenhil, Andrew J

    2016-03-01

    A mechanical device that uses gravitational and spring compression forces to create spatter patterns of known impact velocities is presented and discussed. The custom-made device uses either two or four springs (k1 = 267.8 N/m, k2 = 535.5 N/m) in parallel to create seventeen reproducible impact velocities between 2.1 and 4.0 m/s. The impactor is held at several known spring extensions using an electromagnet. Trigger inputs to the high-speed video camera allow the user to control the magnet's release while capturing video footage simultaneously. A polycarbonate base is used to allow for simultaneous monitoring of the side and bottom views of the impact event. Twenty-four patterns were created across the impact velocity range and analyzed using HemoSpat. Area of origin estimations fell within an acceptable range (ΔXav = -5.5 ± 1.9 cm, ΔYav = -2.6 ± 2.8 cm, ΔZav = +5.5 ± 3.8 cm), supporting distribution analysis for the use in research or bloodstain pattern training. This work provides a framework for those interested in developing a robust impact device.

  3. Effect of modest salt reduction on blood pressure, urinary albumin, and pulse wave velocity in white, black, and Asian mild hypertensives.

    Science.gov (United States)

    He, Feng J; Marciniak, Maciej; Visagie, Elisabeth; Markandu, Nirmala D; Anand, Vidya; Dalton, R Neil; MacGregor, Graham A

    2009-09-01

    A reduction in salt intake lowers blood pressure. However, most previous trials were in whites with few in blacks and Asians. Salt reduction may also reduce other cardiovascular risk factors (eg, urinary albumin excretion, arterial stiffness). However, few well-controlled trials have studied these effects. We carried out a randomized double-blind crossover trial of salt restriction with slow sodium or placebo, each for 6 weeks, in 71 whites, 69 blacks, and 29 Asians with untreated mildly raised blood pressure. From slow sodium to placebo, urinary sodium was reduced from 165+/-58 (+/-SD) to 110+/-49 mmol/24 hours (9.7 to 6.5 g/d salt). With this reduction in salt intake, there was a significant decrease in blood pressure from 146+/-13/91+/-8 to 141+/-12/88+/-9 mm Hg (P<0.001), urinary albumin from 10.2 (IQR: 6.8 to 18.9) to 9.1 (6.6 to 14.0) mg/24 hours (P<0.001), albumin/creatinine ratio from 0.81 (0.47 to 1.43) to 0.66 (0.44 to 1.22) mg/mmol (P<0.001), and carotid-femoral pulse wave velocity from 11.5+/-2.3 to 11.1+/-1.9 m/s (P<0.01). Subgroup analysis showed that the reductions in blood pressure and urinary albumin/creatinine ratio were significant in all groups, and the decrease in pulse wave velocity was significant in blacks only. These results demonstrate that a modest reduction in salt intake, approximately the amount of the current public health recommendations, causes significant falls in blood pressure in all 3 ethnic groups. Furthermore, it reduces urinary albumin and improves large artery compliance. Although both could be attributable to the falls in blood pressure, they may carry additional benefits on reducing cardiovascular disease above that obtained from the blood pressure falls alone.

  4. Carbon dioxide induced changes in cerebral blood flow and flow velocity: Role of cerebrovascular resistance and effective cerebral perfusion pressure

    NARCIS (Netherlands)

    F. Grüne (Frank); S. Kazmaier (Stephan); R.J. Stolker (Robert J.); G.H. Visser (Gerhard Henk); A. Weyland (Andreas)

    2015-01-01

    textabstractIn addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO2 -induced changes in CBF, CVR,

  5. 速度向量成像评价正常成人右心室应变和应变率%Quantitative analysis of strain and strain rate of right ventricular in normal subjects by velocity vector imaging

    Institute of Scientific and Technical Information of China (English)

    侯海军; 智光; 张晓娟; 周肖; 徐勇

    2008-01-01

    目的 应用速度向量成像定量分析正常成人右室心肌应变和应变率.方法 选取健康成人32例,在心尖四腔观测量右室游离壁和室间隔右室面基底段、中间段、心尖段6个节段的应变和应变率收缩期峰值,Simpson法测量右室容量及射血分数.结果 Simpson法及速度向量成像法测量的正常右室射血分数高度相关(r=0.91,P<0.01),右室游离壁基底段和中间段的应变、应变率均高于心尖段(P<0.05).二者的应变和应变率差异均无统计学意义(P>0.05),室间隔右室面的应变和应变率也有相同的规律,右室游离壁基底段和中间段的应变和应变率高于相应室间隔节段(P<0.05),右室游离壁心尖段和室间隔心尖段的应变和应变率无明显差异,右室的应变和应变率和年龄无明显的相关性.结论 速度向量成像技术可以准确定量评估右室室壁应变和应变率.%Objective To investigate strain and strain rate of right ventricular(RV)based on twodimensional image by velocity vector imaging in normal subjects.Methods Thirty-two healthy adults were rolled in this study.Echocardiographic images in 4 chamber view were analyzed by conventional manual tracing for volumes and ejection fractions,which were also measured by velocity vector imaging.Myocardial velocity,strain rate,and strain were determined at the basal,mid,and apical segments of the RV free wall and ventricular septum by velocity vector imaging.Results RV ejection fractions obtained with manual tracing correlated strongly with the same indexes obtained by velocity vector imaging method in all subjects(r=0.91,P<0.01).The strain and strain rate value of middle segment and basal segment in RV free wall were higher than those of apical segment.There were same trend in ventricular septal.The strain and strain rate of middle segment and basal segment in RV free wall were higher than those of homologous segments in ventricular septal,but the indexes

  6. Vector Flow Imaging Compared with Conventional Doppler Ultrasound and Thermodilution for Estimation of Blood Flow in the Ascending Aorta

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper;

    2017-01-01

    Transverse oscillation (TO) is a real-time ultrasound vector flow method implemented on a commercial scanner. The TO setup was examined on a flowrig with constant and pulsatile flow. Subsequently, 25 patients undergoing cardiac bypass surgery were scanned intraoperatively with TO on the ascending...

  7. Polymerase chain reaction (PCR) identification of rodent blood meals confirms host sharing by flea vectors of plague

    NARCIS (Netherlands)

    Franklin, Heather A.; Stapp, Paul; Cohen, Amybeth

    2010-01-01

    Elucidating feeding relationships between hosts and parasites remains a significant challenge in studies of the ecology of infectious diseases, especially those involving small or cryptic vectors. Black-tailed prairie dogs (Cynomys ludovicianus) are a species of conservation importance in the North

  8. Blood

    Science.gov (United States)

    ... Also, blood is either Rh-positive or Rh-negative. So if you have type A blood, it's either A positive or A negative. Which type you are is important if you need a blood transfusion. And your Rh factor could be important ...

  9. Real-Time Path Planning of UAV Based on Velocity Vector%基于速度矢量场的无人机实时动态航路规划

    Institute of Scientific and Technical Information of China (English)

    李春涛; 易小芹; 胡木

    2012-01-01

    An on-line real-time path planning is proposed for unmanned aerial vehicle (UAV) in two-dimensional dynamic environment. A real-time planning method based on velocity vector field is developed in which the environment model is established based on the properties of special area such as radar, mountains etc. Then the driven mechanism of velocity vector field is constructed in order to realize the route planning for UAV. To solve the inherent limitations of vector field, the virtual target point is introduced to deal with the trap caused by losing lots of environment information. The detecting-step method is used to meet the requirements of maneuver capability of UAV. The simulation results show that the method based on velocity vector field is effective and feasible in real-time path planning of UAV.%针对局域动态环境中无人机实时航路规划展开研究,提出了一种基于速度矢量场的二维动态实时航路规划方法.通过建立不同空间特征区域速度场模型,实现了速度场驱动下的无人机航路规划.文中采用虚拟目标点法解决了速度矢量场航路规划局部陷阱问题;采用探测步长法,实现了无人机机动约束的融合,解决了航路可飞性问题;在动态实时规划应用中,确立了环境信息更新方法,实现了对动态环境的描述.通过仿真验证,表明速度矢量场法能够根据动态环境信息及时规避威胁到达目标点,算法具有良好的完备性和实时性,适用于局域动态环境中的快速航迹规划.

  10. Stable Delivery of CCR5-Directed shRNA into Human Primary Peripheral Blood Mononuclear Cells and Hematopoietic Stem/Progenitor Cells via a Lentiviral Vector

    Science.gov (United States)

    Shimizu, Saki; Yadav, Swati Seth; An, Dong Sung

    2016-01-01

    RNAi is a powerful tool to achieve suppression of a specific gene expression and therefore it has tremendous potential for gene therapy applications. A number of vector systems have been developed to express short-hairpin RNAs (shRNAs) to produce siRNAs within mammalian T-cells, primary hematopoietic stem/progenitor cells (HSPC), human peripheral blood mononuclear cells, and in animal model systems. Among these, vectors based on lentivirus backbones have significantly transformed our ability to transfer shRNAs into nondividing cells, such as HSPC, resulting in high transduction efficiencies. However, delivery and long-term expression of shRNAs should be carefully optimized for efficient knock down of target gene without causing cytotoxicity in mammalian cells. Here, we describe our protocols for the development of shRNA against a major HIV co-receptor/chemokine receptor CCR5 and the use of lentiviral vectors for stable shRNA delivery and expression in primary human PBMC and HSPC. PMID:26472455

  11. Assessment value of blood flow velocity and resistance index detection by transvaginal color Doppler ultrasound on effect of neoadjuvant chemotherapy for ovarian cancer

    Institute of Scientific and Technical Information of China (English)

    You-Bin Fan

    2016-01-01

    Objective:To analyze the assessment value of blood flow velocity and resistance index detection by transvaginal color Doppler ultrasound on effect of neoadjuvant chemotherapy for ovarian cancer.Methods:A total of 78 cases of ovarian cancer patients receiving treatment in our hospital from September 2012 to May 2014 were included for study, all patients received neoadjuvant chemotherapy, and before and after treatment, transvaginal color Doppler ultrasound (TVCDU) was used to record resistance index (RI) and pulsatility index (PI), the expression levels of serum tumor markers, illness-related indicators and apoptosis-related factors in circulating blood were detected, and the correlation between TVCDU monitoring indexes and ovarian cancer-related indicators was further analyzed.Results: PI value (1.13±0.12) and RI value (0.65±0.05) of ovarian cancer patients after treatment were significantly higher than PI value (0.72±0.06) and RI value (0.32±0.03) of ovarian cancer patients before treatment; serum HE4, CA153, CA125 and毬-HCG levels of ovarian cancer patients after treatment were lower than those before treatment; serum MSLN, CCL-18, FS, CL and Hpa levels of ovarian cancer patients after treatment were lower than those before treatment; after ovarian cancer patients received neoadjuvant chemotherapy, ADM, HIF-1毩, PCNA and bcl-2 gene expression levels were lower than those before treatment; RI and PI values of ovarian cancer patients were inversely proportional to the expression levels of HE4, CA153, CA125,毬-HCG, MSLN, CCL-18, FS, CL, Hpa, ADM, HIF-1毩, PCNA and bcl-2. Conclusion:Blood flow velocity and resistance index detection by transvaginal color Doppler ultrasound can be used as a highly efficient means to evaluate the effect of neoadjuvant chemotherapy for ovarian cancer, and it has positive significance in judging disease severity, guiding treatment and other aspects.

  12. MULTI-BEHAVIOR INTEGRATED-DECISION METHOD BASED ON FEASIBILITY OF VELOCITY VECTORS%基于速度矢量可行度的移动机器人多行为综合决策方法

    Institute of Scientific and Technical Information of China (English)

    赵忆文; 谈大龙

    2001-01-01

    为了提高机器人对真实环境的适应能力,基于行为思想越来越多地被用于自主机器人的在线运动决策.由此,产生了多行为综合管理问题.本文分析了常用的基于矢量合成的并行行为的综合方法.在此基础上,提出基于速度矢量可行度的自主移动机器人多行为综合决策方法.该方法可较完整地保留子行为的决策意图,得到更合理的行为综合结果.%The idea of behavior-based architecture is applied in autonomous robots more widely to make robots work in real world. This brings out a problem of organizing multiple behaviors. Vector-based methods are often used for integration of parallel behaviors. After analyzing vector-based methods, an integrated method based on feasibility of velocity vectors was provided. This method can keep more information of behavior decision and get better results of behavior integration.

  13. Structure and ligand-binding properties of the biogenic amine-binding protein from the saliva of a blood-feeding insect vector of Trypanosoma cruzi

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xueqing; Chang, Bianca W. [NIH/NIAID, 12735 Twinbrook Parkway, Rockville, MD 20852 (United States); Mans, Ben J. [NIH/NIAID, 12735 Twinbrook Parkway, Rockville, MD 20852 (United States); Agricultural Research Council, Onderstepoort 0110 (South Africa); Ribeiro, Jose M. C.; Andersen, John F., E-mail: jandersen@niaid.nih.gov [NIH/NIAID, 12735 Twinbrook Parkway, Rockville, MD 20852 (United States)

    2013-01-01

    Biogenic amine-binding proteins mediate the anti-inflammatory and antihemostatic activities of blood-feeding insect saliva. The structure of the amine-binding protein from R. prolixus reveals the interaction of biogenic amine ligands with the protein. Proteins that bind small-molecule mediators of inflammation and hemostasis are essential for blood-feeding by arthropod vectors of infectious disease. In ticks and triatomine insects, the lipocalin protein family is greatly expanded and members have been shown to bind biogenic amines, eicosanoids and ADP. These compounds are potent mediators of platelet activation, inflammation and vascular tone. In this paper, the structure of the amine-binding protein (ABP) from Rhodnius prolixus, a vector of the trypanosome that causes Chagas disease, is described. ABP binds the biogenic amines serotonin and norepinephrine with high affinity. A complex with tryptamine shows the presence of a binding site for a single ligand molecule in the central cavity of the β-barrel structure. The cavity contains significant additional volume, suggesting that this protein may have evolved from the related nitrophorin proteins, which bind a much larger heme ligand in the central cavity.

  14. Glytube: a conical tube and parafilm M-based method as a simplified device to artificially blood-feed the dengue vector mosquito, Aedes aegypti.

    Directory of Open Access Journals (Sweden)

    André Luis Costa-da-Silva

    Full Text Available Aedes aegypti, the main vector of dengue virus, requires a blood meal to produce eggs. Although live animals are still the main blood source for laboratory colonies, many artificial feeders are available. These feeders are also the best method for experimental oral infection of Ae. aegypti with Dengue viruses. However, most of them are expensive or laborious to construct. Based on principle of Rutledge-type feeder, a conventional conical tube, glycerol and Parafilm-M were used to develop a simple in-house feeder device. The blood feeding efficiency of this apparatus was compared to a live blood source, mice, and no significant differences (p = 0.1189 were observed between artificial-fed (51.3% of engorgement and mice-fed groups (40.6%. Thus, an easy to assemble and cost-effective artificial feeder, designated "Glytube" was developed in this report. This simple and efficient feeding device can be built with common laboratory materials for research on Ae. aegypti.

  15. Reconsideration of Anopheles rivulorum as a vector of Plasmodium falciparum in western Kenya: some evidence from biting time, blood preference, sporozoite positive rate, and pyrethroid resistance

    Directory of Open Access Journals (Sweden)

    Kawada Hitoshi

    2012-10-01

    Full Text Available Abstract Background Anopheles gambiae, An. arabiensis, and An. funestus are widespread malaria vectors in Africa. Anopheles rivulorum is the next most widespread species in the An. funestus group. The role of An. rivulorum as a malaria vector has not been fully studied, although it has been found to be a minor or opportunistic transmitter of Plasmodium falciparum. Methods Mosquitoes were collected indoors over a 12-hour period using a light source attached to a rotating bottle collector in order to determine peak activity times and to provide DNA for meal source identification. Gravid female mosquitoes were collected indoors via an aspirator to generate F1 progeny for testing insecticidal susceptibility. Blood meal sources were identified using a multiplexed PCR assay for human and bovine cytochrome-B, and by matching sequences generated with primers targeting vertebrate and mammalian cytochrome-B segments to the Genbank database. Results Anopheles rivulorum fed on human blood in the early evening between 18:00 and 20:00, when insecticide-treated bed nets are not in use, and the presence of Plasmodium falciparum sporozoites in 0.70% of the An. rivulorum individuals tested was demonstrated. Susceptibility to permethrin, deltamethrin, and DDT is higher in An. rivulorum (84.8%, 91.4%, and 100%, respectively than in An. funestus s.s. (36.8%, 36.4%, and 70%, respectively, whereas mortality rates for propoxur and fenitrothion were 100% for both species. Resistance to pyrethroids was very high in An. funestus s.s. and the potential of the development of high resistance was suspected in An. rivulorum. Conclusion Given the tendency for An. rivulorum to be active early in the evening, the presence of P. falciparum in the species, and the potential for the development of pyrethroid resistance, we strongly advocate reconsideration of the latent ability of this species as an epidemiologically important malaria vector.

  16. Pulse Wave Velocity as Marker of Preclinical Arterial Disease: Reference Levels in a Uruguayan Population Considering Wave Detection Algorithms, Path Lengths, Aging, and Blood Pressure

    Directory of Open Access Journals (Sweden)

    Ignacio Farro

    2012-01-01

    Full Text Available Carotid-femoral pulse wave velocity (PWV has emerged as the gold standard for non-invasive evaluation of aortic stiffness; absence of standardized methodologies of study and lack of normal and reference values have limited a wider clinical implementation. This work was carried out in a Uruguayan (South American population in order to characterize normal, reference, and threshold levels of PWV considering normal age-related changes in PWV and the prevailing blood pressure level during the study. A conservative approach was used, and we excluded symptomatic subjects; subjects with history of cardiovascular (CV disease, diabetes mellitus or renal failure; subjects with traditional CV risk factors (other than age and gender; asymptomatic subjects with atherosclerotic plaques in carotid arteries; patients taking anti-hypertensives or lipid-lowering medications. The included subjects (n=429 were categorized according to the age decade and the blood pressure levels (at study time. All subjects represented the “reference population”; the group of subjects with optimal/normal blood pressures levels at study time represented the “normal population.” Results. Normal and reference PWV levels were obtained. Differences in PWV levels and aging-associated changes were obtained. The obtained data could be used to define vascular aging and abnormal or disease-related arterial changes.

  17. Influence of upper body position on middle cerebral artery blood velocity during continuous positive airway pressure breathing

    DEFF Research Database (Denmark)

    Højlund Rasmussen, J; Mantoni, T; Belhage, B;

    2007-01-01

    in 11 healthy subjects during CPAP at different body positions (15 degrees head-down tilt, supine, 15 degrees, 30 degrees and 45 degrees upper body elevation). In the supine position, 10 cmH(2)O of CPAP reduced MCA V(mean) by 9 +/- 3% and increased cHbT by 4 +/- 2 micromol/L (mean +/- SEM); (P ....05). In the head-down position, CPAP increased cHbT to 13 +/- 2 micromol/L but left MCA V(mean) unchanged. Upper body elevation by 15 degrees attenuated the CPAP associated reduction in MCA V(mean) (-7 +/- 2%), while cHbT returned to baseline (1 +/- 2 micromol/L). With larger elevation of the upper body MCA V......Continuous positive airway pressure (CPAP) is a treatment modality for pulmonary oxygenation difficulties. CPAP impairs venous return to the heart and, in turn, affects cerebral blood flow (CBF) and augments cerebral blood volume (CBV). We considered that during CPAP, elevation of the upper body...

  18. Pressure and velocity cross-spectrum of normal modes in low-frequency acoustic vector field of shallow water and its application

    Institute of Scientific and Technical Information of China (English)

    Yun Yu; Qing Ling,; Jiang Xu

    2015-01-01

    The pressure and horizontal particle velocity combined descriptions in the very low frequency acoustic field of shal ow wa-ter integrated with the concept of effective depth of Pekeris wave-guide is proposed, especial y the active component of the pressure and horizontal particle velocity cross-spectrum, also cal ed ho-rizontal complex cross acoustic intensity, when only two normal modes are trapped in the waveguide. Both the approximate theo-retic analysis and the numerical results show that the sign of the horizontal complex cross acoustic intensity active component is independent of the range when vertical y deployed receiving dual sensors are placed in appropriate depths, the sum of which is equal to the waveguide effective depth, so it can be used to tel whether the sound source is near the surface or underwater;while the range rate is expected to be measured by utilizing the sign distribution characteristic of the reactive component. The further robustness analysis of the depth classification algorithm shows that the existence of shear waves in semi infinite basement and the change of acoustic velocity profiles have few effects on the application of this method, and the seabed attenuation wil limit the detection range, but the algorithm stil has a good robustness in the valid detection range.

  19. Collagen-binding protein, Aegyptin, regulates probing time and blood feeding success in the dengue vector mosquito, Aedes aegypti.

    Science.gov (United States)

    Chagas, Andrezza Campos; Ramirez, José Luis; Jasinskiene, Nijole; James, Anthony A; Ribeiro, José M C; Marinotti, Osvaldo; Calvo, Eric

    2014-05-13

    Mosquito salivary glands have important roles in blood feeding and pathogen transmission. However, the biological relevance of many salivary components has yet to be determined. Aegyptin, a secreted salivary protein from Aedes aegypti, binds collagen and inhibits platelet aggregation and adhesion. We used a transgenic approach to study the relevance of Aegyptin in mosquito blood feeding. Aedes aegypti manipulated genetically to express gene-specific inverted-repeat RNA sequences exhibited significant reductions in Aegyptin mRNA accumulation (85-87%) and protein levels (>80-fold) in female mosquito salivary glands. Transgenic mosquitoes had longer probing times (78-300 s, P transgenic mosquitoes failed to inhibit collagen-induced platelet aggregation in vitro. Reductions of Aegyptin did not affect salivary ADP-induced platelet aggregation inhibition or disturb anticlotting activities. Our results demonstrate the relevance of Aegyptin for A. aegypti blood feeding, providing further support for the hypothesis that platelet aggregation inhibition is a vital salivary function in blood feeding arthropods. It has been suggested that the multiple mosquito salivary components mediating platelet aggregation (i.e., Aegyptin, apyrase, D7) represent functional redundancy. Our findings do not support this hypothesis; instead, they indicate that multiple salivary components work synergistically and are necessary to achieve maximum blood feeding efficiency.

  20. Assessment of regional right ventricular longitudinal function in fetus using velocity vector imaging%速度向量成像技术检测胎儿右心室长轴节段功能的临床研究

    Institute of Scientific and Technical Information of China (English)

    蒲大容; 周启昌; 彭清海; 曾施; 徐赣琼

    2009-01-01

    Objective To evaluate regional right ventricular longitudinal function in fetus using velocity vector imaging(VVI),and establish nomogram of right ventricle,Methods One hundreed and seventy healthy fetuses were divided into 5 groups according to the gestational age.Dynamic digital views of four chamber view were collected and analyzed offline.Velocity,strain and strain rate were calculated in systolic and diastolic period,respectively.Results Normal systolic and diastolic values for velocity,strain and strain rate were established.Tissue velocity gradually decreased from the base segment to the apical segment(P<0.05),whereas strain and strain rate were stable(P>0.05).Tissue velocity was gestationalage dependent(P<0.05),whereas strain and strain rate were stable throughout gestation (P>0.05).Conclusions Fetal myocardial velocity,strain and strain rate measurements are easy to obtain and reproducible.Increase in tissue velocity throughout gestation probably reflects the growth of the fetal heart,whereas intrinsic myocardial properties as measured by strain and strain rate do not change.%目的 应用速度向量成像(VVI)技术检测胎儿右心室长轴节段功能.方法 分别检测170例正常胎儿右室游离壁和室间隔右室壁各节段长轴心肌速度、应变和应变率,并观察其与孕周的关系.结果 胎儿右室壁收缩期和舒张期峰值速度由基底段向心尖段递减(P<0.05),峰值应变和应变率无明显变化(P>0.05);右室壁收缩期和舒张期峰值速度随孕周增加而增加(P<0.05),峰值应变和应变率与孕周无明显关系(P>0.05).结论 胎儿右室壁收缩期和舒张期峰值速度随妊娠进展增加,峰值应变和应变率保持不变,表明胎儿右室功能在妊娠中期已基本发育成熟.

  1. Vector Flow Imaging Compared with Conventional Doppler Ultrasound and Thermodilution for Estimation of Blood Flow in the Ascending Aorta

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper

    2017-01-01

    aorta and compared to transesophageal echocardiography (TEE) and pulmonary artery catheter thermodilution (PACTD). On the flowrig, TO had a precision of 5.5%, 9.4% and 14.7%, a percentage error of 18.2%, 14.6% and 40.7%, and a mean bias of 0.4 cm/s, 36.8 ml/min and 32.4 ml/min for velocity and flow rate...

  2. A novel peptide delivers plasmids across blood-brain barrier into neuronal cells as a single-component transfer vector.

    Directory of Open Access Journals (Sweden)

    Ailing Fu

    Full Text Available There is no data up to now to show that peptide can deliver plasmid into brain as a single-component transfer vector. Here we show that a novel peptide, RDP (consisted of 39 amino acids, can be exploited as an efficient plasmid vector for brain-targeting delivery. The plasmids containing Lac Z reporter gene (pVAX-Lac Z and BDNF gene (pVAX-BDNF are complexed with RDP and intravenously injected into mice. The results of gel retardation assay show that RDP enables to bind DNA in a dose-dependent manner, and the X-Gal staining identity that Lac Z is specifically expressed in the brain. Also, the results of Western blot and immunofluorescence staining of BDNF indicate that pVAX-BDNF complexed with RDP can be delivered into brain, and show neuroprotective properties in experimental Parkinson's disease (PD model. The results demonstrate that RDP enables to bind and deliver DNA into the brain, resulting in specific gene expression in the neuronal cells. This strategy provides a novel, simple and effective approach for non-viral gene therapy of brain diseases.

  3. A novel peptide delivers plasmids across blood-brain barrier into neuronal cells as a single-component transfer vector.

    Science.gov (United States)

    Fu, Ailing; Zhang, Miaomiao; Gao, Feiyan; Xu, Xingran; Chen, Zhangbao

    2013-01-01

    There is no data up to now to show that peptide can deliver plasmid into brain as a single-component transfer vector. Here we show that a novel peptide, RDP (consisted of 39 amino acids), can be exploited as an efficient plasmid vector for brain-targeting delivery. The plasmids containing Lac Z reporter gene (pVAX-Lac Z) and BDNF gene (pVAX-BDNF) are complexed with RDP and intravenously injected into mice. The results of gel retardation assay show that RDP enables to bind DNA in a dose-dependent manner, and the X-Gal staining identity that Lac Z is specifically expressed in the brain. Also, the results of Western blot and immunofluorescence staining of BDNF indicate that pVAX-BDNF complexed with RDP can be delivered into brain, and show neuroprotective properties in experimental Parkinson's disease (PD) model. The results demonstrate that RDP enables to bind and deliver DNA into the brain, resulting in specific gene expression in the neuronal cells. This strategy provides a novel, simple and effective approach for non-viral gene therapy of brain diseases.

  4. Host choice and multiple blood feeding behaviour of malaria vectors and other anophelines in Mwea rice scheme, Kenya

    Directory of Open Access Journals (Sweden)

    Jacob Benjamin G

    2008-02-01

    Full Text Available Abstract Background Studies were conducted between April 2004 and February 2006 to determine the blood-feeding pattern of Anopheles mosquitoes in Mwea Kenya. Methods Samples were collected indoors by pyrethrum spay catch and outdoors by Centers for Disease Control light traps and processed for blood meal analysis by an Enzyme-linked Immunosorbent Assay. Results A total of 3,333 blood-fed Anopheles mosquitoes representing four Anopheles species were collected and 2,796 of the samples were assayed, with Anopheles arabiensis comprising 76.2% (n = 2,542 followed in decreasing order by Anopheles coustani 8.9% (n = 297, Anopheles pharoensis 8.2% (n = 272 and Anopheles funestus 6.7% (n = 222. All mosquito species had a high preference for bovine (range 56.3–71.4% over human (range 1.1–23.9% or goat (0.1–2.2% blood meals. Some individuals from all the four species were found to contain mixed blood meals. The bovine blood index (BBI for An. arabiensis was significantly higher for populations collected indoors (71.8%, than populations collected outdoors (41.3%, but the human blood index (HBI did not differ significantly between the two populations. In contrast, BBI for indoor collected An. funestus (51.4% was significantly lower than for outdoor collected populations (78.0% and the HBI was significantly higher indoors (28.7% than outdoors (2.4%. Anthropophily of An. funestus was lowest within the rice scheme, moderate in unplanned rice agro-ecosystem, and highest within the non-irrigated agro-ecosystem. Anthropophily of An. arabiensis was significantly higher in the non-irrigated agro-ecosystem than in the other agro-ecosystems. Conclusion These findings suggest that rice cultivation has an effect on host choice by Anopheles mosquitoes. The study further indicate that zooprophylaxis may be a potential strategy for malaria control, but there is need to assess how domestic animals may influence arboviruses epidemiology before adapting the strategy.

  5. Parasites and vector-borne pathogens in client-owned dogs in Albania. Blood pathogens and seroprevalences of parasitic and other infectious agents.

    Science.gov (United States)

    Hamel, Dietmar; Shukullari, Enstela; Rapti, Dhimitër; Silaghi, Cornelia; Pfister, Kurt; Rehbein, Steffen

    2016-02-01

    Knowledge on the epidemiology of parasitic and vector-borne infections is still very limited for Albania, a country located in the Balkan Peninsula in southeast Europe. Recent publications indicated prevalence rates of up to 52% for vector-borne infections in less-cared dogs in Albania. To provide data on the epidemiological situation in dogs under veterinary care, a total of 602 client-owned dogs presented to four small animal clinics between March 2010 and April 2011 in Tirana, Albania, were screened by examination of Giemsa-stained blood smears, PCR, and serological methods for the presence of arthropod-borne infections, as well as Neospora caninum and Toxoplasma gondii. Eight different pathogens, namely Babesia vogeli, Hepatozoon canis, Leishmania infantum, Dirofilaria immitis, Anaplasma phagocytophilum, Anaplasma platys, Ehrlichia canis, and Mycoplasma haemocanis, were detected by direct methods with prevalence rates ranging from 1 to 9%. Seroprevalence for Babesia spp., L. infantum, Anaplasma spp., and E. canis were 6.6, 5.1, 24.1, and 20.8%, respectively. Dogs >1 year of age were positive for vector-borne infections significantly more often than younger dogs (p = 0.003). More than half (51.7%) of the dogs were seroreactive to T. gondii and 18.3% to N. caninum. This is the first report on the detection of A. phagocytophilum, A. platys, E. canis, and M. haemocanis by PCR as well as the serological confirmation of exposure of dogs to N. caninum and T. gondii in Albania. The spectrum of pathogens and the seroprevalences for N. caninum and T. gondii in client-owned dogs from Tirana, Albania, are comparable to that reported in other countries in the Mediterranean Basin. The prevalence rates of vector-borne pathogens are at the lower range of that reported in studies from this geographical region. This is probably due to increased awareness of the owners of pet dogs, including better husbandry conditions and ectoparasiticidal treatment, thus limiting exposure

  6. Ecografia transfontanelar com fluxo a cores em recém-nascidos prematuros Intracranial blood flow velocities evaluated by color doppler (duplex in preterm infants

    Directory of Open Access Journals (Sweden)

    Marcelo Cardoso de Assis

    2004-03-01

    Full Text Available Com o objetivo de determinarmos, evolutivamente, a medida da velocidade do fluxo sangüíneo nas artérias intracranianas, em recém-nascidos prematuros (RNP normais e com hemorragia intracerebral, avaliamos - no período de junho de 1994 a março de 1999 - 73 recém-nascidos prematuros. A idade gestacional variou de 28 a 36 semanas e o peso ao nascimento variou de 720g a 2530g. O diagnóstico da hemorragia intracerebral foi realizado utilizando-se a ecografia transfontanelar (EGT. Para avaliação seqüencial da medida da velocidade do fluxo sangüíneo nas artérias intracranianas os 73 foram submetidos a EGT, com Doppler pulsátil, no 3º, 7º, 30º e 90º dias de vida. Após obtermos os valores numéricos destas velocidades determinamos o indice de resistência (IR. Ao analisarmos os valores do IR, comparando-se os 2 grupos de RNP, concluimos que os valores do IR são sempre mais elevados nos RNP normais (RNP-N que nos RNP com hemorragia intracerebral (RNP-HIC; que tanto no grupo de RNP normais quanto no grupo de RNP com hemorragia intracerebral os valores do IR decrescem significativamente com o acréscimo da idade dos neonatos. Analisando-se ainda, comparativamente, os valores do IR nos RNP com hemorragia intracerebral, em seus diversos graus, observamos não haver, evolutivamente, diferença estatisticamente significante. Analisando-se também , comparativamente, os valores do IR nos RNP com hemorragia intracerebral localizada no hemisfério cerebral direito ou esquerdo concluimos não haver diferença estatisticamente significante entre os valores do IR obtidos das artérias localizadas no hemisfério cerebral acometido comparados aos valores do IR obtidos do hemisfério cerebral não afetado.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

  7. A Plasmodium vivax plasmid DNA- and adenovirus-vectored malaria vaccine encoding blood stage antigens AMA1 and MSP142 in a prime/boost heterologous immunization regimen partially protects Aotus monkeys against blood stage challenge.

    Science.gov (United States)

    Obaldia, Nicanor; Stockelman, Michael G; Otero, William; Cockrill, Jennifer A; Ganeshan, Harini; Abot, Esteban N; Zhang, Jianfeng; Limbach, Keith; Charoenvit, Yupin; Doolan, Denise L; Tang, De-Chu C; Richie, Thomas L

    2017-02-08

    Malaria is caused by parasites of the genus Plasmodium that are transmitted to humans by the bites of Anopheles mosquitoes. After the elimination of P. falciparum it is predicted that Plasmodium vivax will remain an important cause of morbidity and mortality outside of Africa, stressing the importance of developing a vaccine against malaria. In this study we assess the immunogenicity and protective efficacy of two P. vivax antigens, AMA1 and MSP142 in a recombinant DNA plasmid prime/adenoviral vector (Ad) boost regimen in Aotus monkeys. Groups of 4 to 5 monkeys were immunized with DNA alone, Ad alone, prime/boost regimens of each antigen, prime/boost with both antigens, and empty vector controls, and then subjected to blood stage challenge. The heterologous immunization regimen with the antigen pair was more protective than either antigen alone or both antigens delivered with a single vaccine platform, based on their ability to induced the longest pre-patent period and time to peak parasitemia; the lowest peak and mean parasitemia; the smallest area under the parasitemia curve and the highest self-cured rate. Overall, pre-challenge MSP1 antibody titers strongly correlated with decreased parasite burden. Nevertheless, a significant proportion of immunized animals developed anemia. In conclusion, P. vivax plasmid DNA/Ad5 vaccine encoding blood stage parasite antigens AMA1 and MSP142 in a heterologous prime/boost immunization regimen, provided significant protection against blood-stage challenge in Aotus monkeys, indicating the suitability of these antigens and regimen for further development.

  8. BLOOD-SUCKING MIDGES FROM THE GENUS Culicoides (Diptera: Ceratopogonidae) ACT AS FILED VECTORS OF HUMAN AND ANIMAL DISEASES (review)

    OpenAIRE

    2015-01-01

    Bluetongue and Shmallenberg diseases, the arboviral infections of ruminants, caused by Bluetongue virus (BTV) of Orbivirus genus (Reoviridae) and so-called Shmallenberg virus (SBV) preliminarily attributed as a member of Orthobunyavirus genus (Bunyaviridae), respectively, are mainly transmitted by blood-sucking midges from Culicoides genus. They are widely distributed, with a total of over 80 species documented in Russia (V.M. Glukhova, 1989), including the Far North territories. Of them, a t...

  9. Moonlight and blood-feeding behaviour of Lutzomyia intermedia and Lutzomyia whitmani (Diptera:Psychodidae:Phlebotominae, vectors of American cutaneous leishmaniasis in Brazil

    Directory of Open Access Journals (Sweden)

    Nataly A Souza

    2005-02-01

    Full Text Available Lutzomyia intermedia (Lutz & Neiva, 1912 and L. whitmani (Antunes & Coutinho, 1939 (Diptera: Psychodidae: Phlebotominae, two important vectors of American cutaneous leishmaniasis in Brazil, occur in sympatry in the locality of Posse county, Petrópolis municipality, state of Rio de Janeiro, Brazil. We investigated the influence of the lunar cycle on the frequency of specimens of the two species caught while attempting to bite the collectors and in CDC light traps. Analysis of the numbers of sand flies captured in different lunar phases for two consecutive years in the peridomestic site and forest shows that there is a significant positive correlation between moonlight intensity and the numbers of L. intermedia and L. whitmani females collected while blood-feeding, whereas the opposite was observed for the CDC traps.

  10. Combining viral vectored and protein-in-adjuvant vaccines against the blood-stage malaria antigen AMA1: report on a phase 1a clinical trial.

    Science.gov (United States)

    Hodgson, Susanne H; Choudhary, Prateek; Elias, Sean C; Milne, Kathryn H; Rampling, Thomas W; Biswas, Sumi; Poulton, Ian D; Miura, Kazutoyo; Douglas, Alexander D; Alanine, Daniel Gw; Illingworth, Joseph J; de Cassan, Simone C; Zhu, Daming; Nicosia, Alfredo; Long, Carole A; Moyle, Sarah; Berrie, Eleanor; Lawrie, Alison M; Wu, Yimin; Ellis, Ruth D; Hill, Adrian V S; Draper, Simon J

    2014-12-01

    The development of effective vaccines against difficult disease targets will require the identification of new subunit vaccination strategies that can induce and maintain effective immune responses in humans. Here we report on a phase 1a clinical trial using the AMA1 antigen from the blood-stage Plasmodium falciparum malaria parasite delivered either as recombinant protein formulated with Alhydrogel adjuvant with and without CPG 7909, or using recombinant vectored vaccines--chimpanzee adenovirus ChAd63 and the orthopoxvirus MVA. A variety of promising "mixed-modality" regimens were tested. All volunteers were primed with ChAd63, and then subsequently boosted with MVA and/or protein-in-adjuvant using either an 8- or 16-week prime-boost interval. We report on the safety of these regimens, as well as the T cell, B cell, and serum antibody responses. Notably, IgG antibody responses primed by ChAd63 were comparably boosted by AMA1 protein vaccine, irrespective of whether CPG 7909 was included in the Alhydrogel adjuvant. The ability to improve the potency of a relatively weak aluminium-based adjuvant in humans, by previously priming with an adenoviral vaccine vector encoding the same antigen, thus offers a novel vaccination strategy for difficult or neglected disease targets when access to more potent adjuvants is not possible.

  11. Cloning and characterization of a V-ATPase subunit C from the American visceral leishmaniasis vector Lutzomyia longipalpis modulated during development and blood ingestion

    Directory of Open Access Journals (Sweden)

    JM Ramalho-Ortigão

    2007-06-01

    Full Text Available Visceral leishmaniasis (VL is a serious tropical disease that affects approximately 500 thousand people worldwide every year. In the Americas, VL is caused by the parasite Leishmania (Leishmania infantum chagasi mainly transmitted by the bite of the sand fly vector Lutzomyia longipalpis. Despite recent advances in the study of interaction between Leishmania and sand flies, very little is known about sand fly protein expression profiles. Understanding how the expression of proteins may be affected by blood feeding and/or presence of parasite in the vector's midgut might allow us to devise new strategies for controlling the spread of leishmaniasis. In this work, we report the characterization of a vacuolar ATPase subunit C from L. longipalpis by screening of a midgut cDNA library with a 220 bp fragment identified by means of differential display reverse transcriptase-polymerase chain reaction analysis. The expression of the gene varies along insect development and is upregulated in males and bloodfed L. longipalpis, compared to unfed flies.

  12. Rapid detection and identification of Wuchereria bancrofti, Brugia malayi, B. pahangi, and Dirofilaria immitis in mosquito vectors and blood samples by high resolution melting real-time PCR.

    Science.gov (United States)

    Thanchomnang, Tongjit; Intapan, Pewpan M; Tantrawatpan, Chairat; Lulitanond, Viraphong; Chungpivat, Sudchit; Taweethavonsawat, Piyanan; Kaewkong, Worasak; Sanpool, Oranuch; Janwan, Penchom; Choochote, Wej; Maleewong, Wanchai

    2013-12-01

    A simple, rapid, and high-throughput method for detection and identification of Wuchereria bancrofti, Brugia malayi, Brugia pahangi, and Dirofilaria immitis in mosquito vectors and blood samples was developed using a real-time PCR combined with high-resolution melting (HRM) analysis. Amplicons of the 4 filarial species were generated from 5S rRNA and spliced leader sequences by the real-time PCR and their melting temperatures were determined by the HRM method. Melting of amplicons from W. bancrofti, B. malayi, D. immitis, and B. pahangi peaked at 81.5±0.2℃, 79.0±0.3℃, 76.8±0.1℃, and 79.9±0.1℃, respectively. This assay is relatively cheap since it does not require synthesis of hybridization probes. Its sensitivity and specificity were 100%. It is a rapid and technically simple approach, and an important tool for population surveys as well as molecular xenomonitoring of parasites in vectors.

  13. 体检人群脉搏波传导速度与动态血压监测指标的相关性研究%Relationship between pulse wave velocity and parameters from ambulatory blood pressure monitoring

    Institute of Scientific and Technical Information of China (English)

    李曦; 胡荣; 芦燕玲; 于利群; 周生来

    2013-01-01

    目的:脉搏波传导速度与动态血压监测指标的关系.方法:行动态血压监测的体检者582例,根据血压水平分为正常血压组、血压正常高值组和高血压组,分析脉搏波传导速度与动态血压各指标之间的关系.结果:三组间动态血压各指标显著增高;颈股脉搏波传导速度三组间差异有统计学意义(P<0.05);高血压组颈桡脉搏波传导速度显著高于血压正常组.Pearson相关性分析:颈桡脉搏波传导速度与24 h平均SBP/DBP、白天平均SBP/DBP、夜间平均DBP、白天DBP负荷、夜间DBP负荷均呈正相关.颈股脉搏波传导速度与24h平均SBP、白天/夜间平均SBP、白天/夜间SBP负荷、白天SBP变化标准差均呈正相关.多元线性回归发现颈股脉搏波传导速度与24h平均SBP独立相关,颈桡脉搏波传导速度与白天平均DBP独立相关.结论:随血压水平程度升高,脉搏波传导速度明显增快.%Objective:To investigate relationship between pulse wave velocity and parameters from ambulatory blood pressure monitoring in examination persons.Methods:The 582 examination persons were taken ambulatory blood pressure monitoring and pulse wave velocity,the parameters were analyzed according blood pressure level.Results:The parameters from ambulatory blood pressure monitoring increase obviously in 3 groups.The carotid-femoral pulse wave velocity increase obviously in 3 groups.The carotid-radial pulse wave velocity were higher in hypertension group than normotensive.After analysis of pearson correlation,The carotidradial pulse wave velocity positively correlated with the mean 24h blood pressure,daytime mean blood pressure,night diastolic blood pressure,daytime diastolic blood pressure load,night diastolic blood pressure load.The carotid-femoral pulse wave velocity positively correlated with 24h systolic blood pressure,daytime and night systolic blood pressure,daytime and night systolic blood pressure load,daytime systolic blood

  14. Introducing Vectors.

    Science.gov (United States)

    Roche, John

    1997-01-01

    Suggests an approach to teaching vectors that promotes active learning through challenging questions addressed to the class, as opposed to subtle explanations. Promotes introducing vector graphics with concrete examples, beginning with an explanation of the displacement vector. Also discusses artificial vectors, vector algebra, and unit vectors.…

  15. 影响胎儿大脑中动脉血流峰速的临床相关因素%Related clinical effect factors of peak velocity of blood flow of fetal middle cerebral artery

    Institute of Scientific and Technical Information of China (English)

    凌奕; 金松; 南瑞霞; 华少萍; 张宏玉; 胡春霞; 莫秀兰

    2011-01-01

    Objective: To analyze the related clinical effect factors of peak velocity of blood flow of fetal middle cerebral artery ( MCA) , provide a basis for predicting fetal anemia by peak velocity of blood flow of MCA. Methods; 140 fetuses from the hospital were analyzed and divided into normal control group (85 fetuses), uncomplicated twin group (22 fetuses) , thalassemia group (IS fetuses) and fetal anomaly group (18 fetuses) , all the fetuses received color Doppler examination of peak velocity of blood flow of MCA and hemoglobin detection. MOM value was used as the unit, the differences of peak velocities of blood flow of MCA and fetal hemoglobin contents among the four groups were analyzed. Results; There was no significant difference in peak velocity of blood flow of MCA and fetal hemoglobin content between uncomplicated twin group and single pregnancy group. In thalassemia group, the peak velocity of blood flow of MCA increased significantly , while fetal hemoglobin content decreased. Compared with normal single pregnancy group, the peak velocity of blood flow of MCA in fetal anomaly group increased significantly (P < 0. 05 ) , but after exclusing anemia fetuses, there is no significant difference in the peak velocity of blood flow of MCA between fetal anomaly non - anemia group and normal single pregnancy group. Conclusion: The peak velocity of blood flow of MCA is significantly related to fetal anemia, but there was no correlation between peak velocity of blood now of MCA and un-complicated twin pregnancy; the study shows that there is no significant difference in the peak velocity of blood flow of MCAbetween fetal anomaly non - anemia group and normal single pregnancy group after exclusing anemia fetuses, a further study with large samples is needed.%目的:分析影响胎儿大脑中动脉血流峰速(MCA-PSV)的临床相关因素,为应用MCA-PSV预测胎儿贫血提供依据.方法:对海南医学院附属医院140例胎儿进行临

  16. Plasma Renalase is Not Associated with Blood Pressure and Brachial-Ankle Pulse Wave Velocity in Chinese Adults With Normal Renal Function

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2016-11-01

    Full Text Available Background/Aims: This study aimed to investigate the association of renalase with blood pressure (BP and brachial-ankle pulse wave velocity (baPWV in order to better understand the role of renalase in the pathogenesis of hypertension and atherosclerosis. Methods: A total of 344 subjects with normal kidney function were recruited from our previously established cohort in Shaanxi Province, China. They were divided into the normotensive (NT and hypertensive (HT groups or high baPWV and normal baPWV on the basis of BP levels or baPWV measured with an automatic waveform analyzer. Plasma renalase was determined through an enzyme-linked immunosorbent assay. Results: Plasma renalase did not significantly differ between HT and NT groups (3.71 ± 0.69 µg/mL vs. 3.72 ± 0.73 μg/mL, P = 0.905 and between subjects with and without high baPWV (3.67 ± 0.66 µg/mL vs. 3.73 ± 0.74 µg/mL, P = 0.505. However, baPWV was significantly higher in the HT group than in the NT group (1460.4 ± 236.7 vs. 1240.7 ± 174.5 cm/s, P Conclusion: Plasma renalase may not be associated with BP and baPWV in Chinese subjects with normal renal function.

  17. Influence of acute jugular vein compression on the cerebral blood flow velocity, pial artery pulsation and width of subarachnoid space in humans.

    Directory of Open Access Journals (Sweden)

    Andrzej F Frydrychowski

    Full Text Available PURPOSE: The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1 pial artery pulsation (cc-TQ; (2 cerebral blood flow velocity (CBFV; (3 peripheral blood pressure; and (4 possible relations between mentioned parameters. METHODS: Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS, CBFV in the left anterior cerebral artery using transcranial Doppler, blood pressure was measured using Finapres, while end-tidal CO(2 was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT and swayed to the back (initial position. RESULTS: In the first group (n = 10 during BOPT, sas-TQ and pulse pressure (PP decreased (-17.6% and -17.9%, respectively and CBFV increased (+35.0%, while cc-TQ did not change (+1.91%. In the second group, in the initial position (n = 22 cc-TQ and CBFV increased (106.6% and 20.1%, respectively, while sas-TQ and PP decreases were not statistically significant (-15.5% and -9.0%, respectively. End-tidal CO(2 remained stable during BOPT and venous compression in both groups. Significant interdependence between changes in cc-TQ and PP after bilateral jugular vein compression in the initial position was found (r = -0.74. CONCLUSIONS: Acute bilateral jugular venous insufficiency leads to hyperkinetic cerebral circulation characterised by augmented pial artery pulsation and CBFV and direct transmission of PP into the brain microcirculation. The Windkessel effect with impaired jugular outflow and more likely increased intracranial pressure is described. This study clarifies the potential mechanism linking jugular outflow insufficiency with arterial small vessel cerebral

  18. Natural product of wild Zingiberaceae Elettariopsis slahmong: biopesticide to control the vector of banana blood disease bacterium in West Sumatera, Indonesia.

    Science.gov (United States)

    Nasir, N; Dharma, A; Efdi, M; Yuhendra; Eliesti, F

    2013-01-01

    Banana is one of the most important food crops in Indonesia. Its production is greater than any other agricultural commodity. With the population of 230 million in 2010, banana was consumed up to three million tons in this country. However, Banana Blood Disease Bacterium (BDB), one of the most devastating banana pathogens in the world, which is only found in Indonesia, threatens not only the growth of this plant but also the lives and the livelihoods for most of the Indonesian society. BDB is caused by a lethal bacteria, Ralstonia solanacearum Phylotype-4, which infects a wide range of bananas, from bananas used for consumption to wild bananas. In West Sumatera, the disease killed 1.40% of bananas in 1998, and then increased dramatically to 37.9% in 2003. The total banana production dropped to 62% in this province. The search for controlling the vector has led to the pre-investigation of Wild Zingiberaceae Elettariopsis slahmong C.K. Lim which has a stink bug odour similar to a methidathion insecticide. The plant was collected around the conservation area of Lembah Anal in West Sumatra. The goal of this study was to investigate the effectiveness of natural insecticides compound contained in E. slahmong against D. melanogaster. This study tested the effect of E. slahmong on the mortality, anti-feedant and repellent levels against Drosophila melanogaster, the vector of BDB. The essential oil of E. slahmong was obtained by steam distillation of fresh rhizomes, pseudo stems and leaves. We found that the extract of E. slahmong significantly affected the mortality of D. melanogaster of 30-40% and also acted as an antifeedant (with success rate of 73-93%) and repellent (with success rate of 99-99.6%). The long- term objective of this study is to develop green biopesticide to control BDB in Indonesia, based on an environmentally friendly pest management.

  19. 男大学生体成分与脑血流速度相关性研究%The Research on the Relationship Between Body Composition and Cerebral Blood Flow Velocity in Male College Students

    Institute of Scientific and Technical Information of China (English)

    姚宝元

    2012-01-01

    探讨身体成分与脑血流速度(Cerebral Blood Flow Velocity,CBFV)的关系,以便揭示体脂对CBFV的影响。方法:以10名男大学生为实验对象,应用经颅多普勒技术检测了其安静时的大脑中动脉血流速度和采用In Body身体成份分析仪测试了其身体成分,然后对CBFV和身体进行了相关分析。结果:大脑中动脉收缩期峰速度(Vp)、舒张期末峰速度(Vd)和平均峰速度(Vm)分别与其体脂、体脂百分数和体重指数(BMI)呈显著负相关;而大脑中动脉的搏动指数(PI)分别与体脂百分数和BMI呈显著正相关。结论:体脂对CBFV有显著的负面影响,体脂增多,CBFV降低。%By investigating the relationship between body composition and cerebral blood flow velocity, the effect of body fat on cerebral blood flow velocity was evaluated. Methods: The middle cerebral artery blood velocity was evaluated by Using CBS - II transcranial Doppler at rest in ten male college students, and their body composition was assessed by using In Body body Composi- tion analyser at rest. Correlation of body composition to the middle cerebral artery blood velocity was analysed. Results : Vp, Vd and Vm of MCA were negatively related to body fat,body fat percentage and BMI respectively. PI of MCA was positively related to body fat, body fat and BMI percentage, respectively. Conclusion: Our study implies boy fat has significant and negative effect on cerebral blood flow velocity. Cerebral blood flow velocity will reduce when body fat increases.

  20. 99mTc complex conjugated to insulin: CNS radio-pharmaceuticals design based on principles of blood-brain barrier transport vector

    Institute of Scientific and Technical Information of China (English)

    LIU Fei; FAN Caiyun; ZHANG Jinming; WANG Wushang; LIU Boli

    2005-01-01

    Hydrophilic 99mTc-EC and nonlipophilic 99mTc- MAMA′-BA complexes, owing to the existing of intact blood-brain barrier (BBB) in vivo, cannot cross from blood to brain. Previous studies showed that insulin is selectively transported by receptor-mediated transcytosis through the brain capillary endothelial wall that makes up the BBB. In this paper, based on the characteristic of the insulin receptor enriched in brain capillary, the complexes of hydrophilic 99mTc-EC and nonlipophilic 99mTc-MAMA′-BA are conjugated to insulin respectively. After purification, the radiochemical purity of 99mTc-EC-insulin and 99mTc-MAMA′- BA-insulin was > 90% and the stability in vitro was good. Expectation for the special formulation can be internalized and endocytosed into the capillary membrane by the vector-mediated brain delivery system, and transported 99mTc-labeled conjugate through the BBB in vivo, thus enhancing brain uptake in mice. The biodistribution results of 99mTc-EC-insulin and 99mTc-MAMA′-BA-insulin in mice indicated that the brain uptake was higher than 99mTc-EC and 99mTc-MAMA′-BA to some extent. The ratios of brain uptake of 99mTc-EC-insulin to 99mTc-EC, 99mTc-MAMA′-BA-insulin to 99mTc-MAMA′-BA were 4―6 at 2 and 3 h post-injection respectively. In conclusion, the given results have illustrated a new way of brain uptake enhancing for nonlipophilic like complexes that have BBB delivery problems. It has a potential value for the ongoing development of 99mTc-labeled radiopharmaceuticals for CNS receptors imaging.

  1. Energy velocity and group velocity

    Institute of Scientific and Technical Information of China (English)

    陈宇

    1995-01-01

    A new Lagrangian method for studying the relationship between the energy velocity and the group velocity is described. It is proved that under the usual quasistatic electric field, the energy velocity is identical to the group velocity for acoustic waves in anisotropic piezoelectric (or non-piezoelectric) media.

  2. The Independent and Joint Association of Blood Pressure, Serum Total Homocysteine, and Fasting Serum Glucose Levels With Brachial-Ankle Pulse Wave Velocity in Chinese Hypertensive Adults.

    Science.gov (United States)

    Liu, Xiaoyun; Sun, Ningling; Yu, Tao; Fan, Fangfang; Zheng, Meili; Qian, Geng; Wang, Binyan; Wang, Yu; Tang, Genfu; Li, Jianping; Qin, Xianhui; Hou, Fanfan; Xu, Xiping; Yang, Xinchun; Chen, Yundai; Wang, Xiaobin; Huo, Yong

    2016-09-28

    This study aimed to investigate the independent and joint association of blood pressure (BP), homocysteine (Hcy), and fasting blood glucose (FBG) levels with brachial-ankle pulse wave velocity (baPWV, a measure of arterial stiffness) in Chinese hypertensive adults.The analyses included 3967 participants whose BP, Hcy, FBG, and baPWV were measured along with other covariates. Systolic BP (SBP) was analyzed as 3 categories (SBP < 160 mmHg; 160 to 179 mmHg; ≥ 180 mmHg); Hcy as 3 categories (< 10 μmol/L; 10 to 14.9 μmol/L; ≥ 15.0 μmol/L) and FBG: normal (FBG < 5.6 mmol/L), impaired (5.6 mmol/L ≤ FBG < 7.0 mmol/L), and diabetes mellitus (FBG ≥ 7.0 mmol/L). We performed linear regression analyses to evaluate their associations with baPWV with adjustment for covariables.When analyzed individually, BP, Hcy, and FBG were each associated with baPWV. When BP and FBG were analyzed jointly, the highest baPWV value (mean ± SD: 2227 ± 466 cm/s) was observed in participants with FBG ≥ 7.0 mmol/L and SBP ≥ 180 mmHg (β = 432.5, P < 0.001), and the lowest baPWV value (mean ± SD: 1692 ± 289 cm/s) was seen in participants with NFG and SBP < 160 mmHg. When Hcy and FBG were analyzed jointly, the highest baPWV value (2072 ± 480 cm/s) was observed in participants with FBG ≥ 7.0 mmol/L and Hcy ≥ 15.0 μmol/L (β = 167.6, P < 0.001), while the lowest baPWV value (mean ± SD: 1773 ± 334 cm/s) was observed in participants with NFG and Hcy < 10 μmol/L.In Chinese hypertensive adults, SBP, Hcy, and FBG are individually and jointly associated with baPWV.Our findings underscore the importance of identifying individuals with multiple risk factors of baPWV including high SBP, FBG, and Hcy.

  3. 速度向量成像技术对正常胎儿左室心肌纵向运动功能的分析%Evaluation of Left Ventricular Myocardial Longitudinal Function in Normal Fetus by Velocity Vector Imaging

    Institute of Scientific and Technical Information of China (English)

    张雪梅; 李锐; 郭燕丽; 张晓航; 段灵敏; 薛雅方; 唐春霖

    2011-01-01

    Objective To evaluate the left ventricular myocardial longitudinal function in normal fetus by velocity vector imaging (VVI). Methods The standard four-chamber views in 50 normal fetus were collected using VVI mode. The regional tissue velocity, strain, and strain rate of the interventricular septum and left lateral wall were measured using VVI sofeware. Results Left ventriculor myocardial longitudinal funtion in 45 Fetus were evaluated by,Tissue velocity decreased gradually from the basal segment to the apical segment, strain and strain rate were no significant differences among 6 segments. Conclusions VVI was a new technique for analysing myocardial function. left ventricular myocardial longitudinal function can be evaluated in normal fetus.%目的 探讨速度向量成像技术分析正常胎儿左室纵向心肌运动功能的方法,分析正常胎儿左室纵向心肌运动的特征.方法 采用Sequeia 512超声诊断仪,在速度向量成像技术模式下对50例正常胎儿心脏取标准四腔心切面,分析左室侧壁及室间隔基底段、中间段、心尖段节段心肌运动速度、应变及应变率.结果 50例胎儿中45例成功获得速度向量成像技术图像,速度向量成像技术获得左室6个节段心肌任意时间的运动速度、应变及应变率彩色图、曲线及三维图像.左室6个节段心肌运动速度由基底段向心尖段呈递减趋势,心肌应变及应变率无基底段向心尖段递减的分布趋势.结论 速度向量成像技术无角度依赖性,是分析胎儿心肌运动的新技术,可测量节段心肌运动速度、应变及应变率,可用于胎儿心脏左室纵向心肌运动的分析.

  4. Bistatic Radar System Ambiguity Function Analysis Based on Velocity Vector%基于速度矢量的双基地雷达模糊函数分析

    Institute of Scientific and Technical Information of China (English)

    刘勇; 李国君

    2012-01-01

    The bistatic radar system ambiguity function is presented based on monostatic radar system ambiguity function. The bistatic radar system geometry configuration and the targets moving states determine the bistatic radar system ambiguity function features besides the transmitted signal. Supposing transmitting signal is simple Gaussian pulse, the bistatic radar system ambiguity function characterizes different features when target range and velocity vector is changed. The method is suited to any type transmitted pulse. It is valuable to analyze the bistatic radar system resolving and ambiguity of range and veloci-ty.%通过研究双基地雷达系统模糊函数数学模型和当发射信号为高斯单脉冲且目标相对接收机的距离和速度变化时双基地雷达系统模糊函数的特性,分析了目标的速度大小与方向对模糊函数的影响.该模型可有效考核任意发射脉冲信号的双基地雷达系统的分辨力及距离和速度模糊等问题,对研究双基地雷达系统性能有着重要的理论参考价值.

  5. Experimental studies of the blood flow velocity measurement using the echo tracking technique%利用超声回波跟踪技术测量血流速度的实验研究

    Institute of Scientific and Technical Information of China (English)

    汪源源; PeterWEBER

    2001-01-01

    文章主要介绍了利用超声回波跟踪技术进行血流速度测量的原理和方法,通过对运动弦线速度的测量实验,比较了这种方法和传统的超声多普勒技术在血流速度测量上的性能差异。%The theory and method of the blood flow velocity measurement using the ultrasonic echo tracking technique were studied inthis paper. With the experiment of the moving string velocity measurement, the performance of this method was compared with thoseof the conventional Doppler ultrasound blocd flow velocity measurement techniques

  6. Minimizing the blood velocity differences between phase-contrast magnetic resonance imaging and computational fluid dynamics simulation in cerebral arteries and aneurysms.

    Science.gov (United States)

    Mohd Adib, Mohd Azrul Hisham; Ii, Satoshi; Watanabe, Yoshiyuki; Wada, Shigeo

    2017-02-04

    The integration of phase-contrast magnetic resonance images (PC-MRI) and computational fluid dynamics (CFD) is a way to obtain detailed information of patient-specific hemodynamics. This study proposes a novel strategy for imposing a pressure condition on the outlet boundary (called the outlet pressure) in CFD to minimize velocity differences between the PC-MRI measurement and the CFD simulation, and to investigate the effects of outlet pressure on the numerical solution. The investigation involved ten patient-specific aneurysms reconstructed from a digital subtraction angiography image, specifically on aneurysms located at the bifurcation region. To evaluate the effects of imposing the outlet pressure, three different approaches were used, namely: a pressure-fixed (P-fixed) approach; a flow rate control (Q-control) approach; and a velocity-field-optimized (V-optimized) approach. Numerical investigations show that the highest reduction in velocity difference always occurs in the V-optimized approach, where the mean of velocity difference (normalized by inlet velocity) is 19.3%. Additionally, the highest velocity differences appear near to the wall and vessel bifurcation for 60% of the patients, resulting in differences in wall shear stress. These findings provide a new methodology for PC-MRI integrated CFD simulation and are useful for understanding the evaluation of velocity difference between the PC-MRI and CFD.

  7. About vectors

    CERN Document Server

    Hoffmann, Banesh

    1975-01-01

    From his unusual beginning in ""Defining a vector"" to his final comments on ""What then is a vector?"" author Banesh Hoffmann has written a book that is provocative and unconventional. In his emphasis on the unresolved issue of defining a vector, Hoffmann mixes pure and applied mathematics without using calculus. The result is a treatment that can serve as a supplement and corrective to textbooks, as well as collateral reading in all courses that deal with vectors. Major topics include vectors and the parallelogram law; algebraic notation and basic ideas; vector algebra; scalars and scalar p

  8. Vector analysis

    CERN Document Server

    Newell, Homer E

    2006-01-01

    When employed with skill and understanding, vector analysis can be a practical and powerful tool. This text develops the algebra and calculus of vectors in a manner useful to physicists and engineers. Numerous exercises (with answers) not only provide practice in manipulation but also help establish students' physical and geometric intuition in regard to vectors and vector concepts.Part I, the basic portion of the text, consists of a thorough treatment of vector algebra and the vector calculus. Part II presents the illustrative matter, demonstrating applications to kinematics, mechanics, and e

  9. 速度向量成像技术评价正常胎儿左心室功能的研究%Evaluation of left ventricular function in fetus by velocity vector imaging technique

    Institute of Scientific and Technical Information of China (English)

    谢彩丽; 姜志荣; 庞慧燕

    2012-01-01

    Objective To investigate the clinical value of velocity vector imaging ( VVI) technique in assessment of fetal cardiac function. Methods The study included 90 fetuses of normal pregnancy, they were divided into Ⅰ group ( 1 8 ~ 23 +6 gestational weeks) , Ⅱ group ( 24 ~ 27+6 gestational weeks) , Ⅲ group ( 28 ~ 31 +6 gestational weels) , Ⅳ group ( 32 ~ 35+6 gestational weeks) and V group (36 ~40 + l gestational weeks) . Digital dynamic four-chamber images were collected, then the left ventricular- longitudinal indexes were measured , the changes of each index was observed. Results Peak systolic velocity( Vs) and peak diastolic velocity( Vd) were gradually decreased from the base segment to the apical segment (P0. 05). Vs and Vd were increased with the increase of gestational weeks, while there was no significant difference among S, SRs and SRd (P>0.05) with the gestational weeks. Conclusion VVI technique can quantitatively assess regional and global junction of fetal left ventricle, it provides a new useful modality for evaluating fetal cardiac junction.%目的 探讨速度向量成像技术(VVI)评价正常胎儿左心室功能的临床价值.方法 选取90例孕18~40周的正常胎儿,按孕龄分成Ⅰ组(18~23+6周)、Ⅱ组(24~27+6周)、Ⅲ组(28~31+6周)、Ⅳ组(32~35+6周)、Ⅴ组(36~40+1周),收集所有胎儿的动态标准四腔心切面图像,利用VVI软件测量左室侧壁和室间隔左室面心肌长轴方向运动指标,并观察各项指标随孕周的变化趋势.结果 正常胎儿左室侧壁和室间隔左室面收缩期峰值速度(Vs)、舒张期峰值速度(Vd)均由基底段至心尖段逐渐减低(P0.05).左室侧壁和室间隔左室面Vs、Vd均随孕周的增加而增大,而S、SRs和SRd随孕周增加差异无明显变化(P>0.05).结论 VVI可定量评价正常胎儿左心室局部及整体功能,为临床有效地评估胎儿心功能开辟了新的途径.

  10. Demonstrating the Direction of Angular Velocity in Circular Motion

    Science.gov (United States)

    Demircioglu, Salih; Yurumezoglu, Kemal; Isik, Hakan

    2015-01-01

    Rotational motion is ubiquitous in nature, from astronomical systems to household devices in everyday life to elementary models of atoms. Unlike the tangential velocity vector that represents the instantaneous linear velocity (magnitude and direction), an angular velocity vector is conceptually more challenging for students to grasp. In physics…

  11. Elementary vectors

    CERN Document Server

    Wolstenholme, E Œ

    1978-01-01

    Elementary Vectors, Third Edition serves as an introductory course in vector analysis and is intended to present the theoretical and application aspects of vectors. The book covers topics that rigorously explain and provide definitions, principles, equations, and methods in vector analysis. Applications of vector methods to simple kinematical and dynamical problems; central forces and orbits; and solutions to geometrical problems are discussed as well. This edition of the text also provides an appendix, intended for students, which the author hopes to bridge the gap between theory and appl

  12. 速度向量成像技术评价右心室长轴收缩功能的实验研究%Investigation of right ventricular longitudinal systolic function by velocity vector imaging

    Institute of Scientific and Technical Information of China (English)

    侯海军; 李春伶; 张晓娟; 智光

    2009-01-01

    Objective To investigate the feasibility and accuracy of velocity vector imaging(VVI)to assess strain and strain rate of right ventrieule(RV)during varying myocardial functional states.Methods VVI of the longitudinal RV were recorded in 7 closed-chest anesthetized mongrel dogs from the apical 4-chamber view during 3 different inotropic states.Peak dp/dt from the RV contraction during the right cardiac catheterization,which was used as the gold standard of RV contractility,was obtained simultaneously in each inotropic state.Peak systolic velocities(V), peak systolic strain rates(SR),peak systolic strains(S)at the basal, middle and apical segments of RV free wall and septal from the longitudinal axis were quantitatively measured by using VVI software system respectively.Results The peak systolic strain and strain rate of the longitudinal RV free wall and septal were increased with the infusion of dobutamine and decreased with the infusion of metoprolol.A significant correlation was found between peak RV dp/dt and RV mean strain and mean strain rate(r=0.79, 0.75;P <0.01).Among all RV segments, the peak systolic S,SR of RV basal free wall had the most significant correlation to peak dp/dt (r=0.83,0.78;P<0.01).Conclusions Strain rate imaging drived from VVI could quantitatively and sensitively detect the longitudinal RV contractile function.Peak systolic S and SR determined at the longitudinal RV basal free wall were the strong noninvasive indices of RV contractility.%目的 探讨速度向量成像(VVI)对右心室功能检测的可行性及准确性.方法 采集7只实验犬在3种不同心肌收缩功能状态下的右室长轴VVI图像,同步记录右室收缩期最大压力上升速率(dp/dt_(max)),分别测量右室游离壁和室间隔基底段、中间段、心尖段收缩期峰值速度(V)、峰值应变(S)和峰值应变率(SR),并与右心导管检查测定的右室dp/dt_(max)作相关分析.结果 应用多巴酚丁胺后右室应变和应变率明显增

  13. Intra-operative Vector Flow Imaging Using Ultrasound of the Ascending Aorta among 40 Patients with Normal, Stenotic and Replaced Aortic Valves

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper

    2016-01-01

    Stenosis of the aortic valve gives rise to more complex blood flows with increased velocities. The angleindependent vector flow ultrasound technique transverse oscillation was employed intra-operatively on the ascending aorta of (I) 20 patients with a healthy aortic valve and 20 patients with aor......Stenosis of the aortic valve gives rise to more complex blood flows with increased velocities. The angleindependent vector flow ultrasound technique transverse oscillation was employed intra-operatively on the ascending aorta of (I) 20 patients with a healthy aortic valve and 20 patients...... (p , 0.52 and p , 0.22), but flow complexity was not (p , 0.0001). Flow complexity (p , 0.0001), systolic jet width (p , 0.0001) and systolic backflow (p , 0.001) were associated with peak systolic velocity. The study found that aortic stenosis changes blood flow in the ascending aorta and valve...

  14. Hybrid PIV-PTV technique for measuring blood flow in rat mesenteric vessels.

    Science.gov (United States)

    Ha, Hojin; Nam, Kweon-Ho; Lee, Sang Joon

    2012-11-01

    The micro-particle tracking velocimetry (μ-PTV) technique is used to obtain the velocity fields of blood flow in the microvasculature under in vivo conditions because it can provide the blood velocity distribution in microvessels with high spatial resolution. The in vivo μ-PTV technique usually requires a few to tens of seconds to obtain a whole velocity profile across the vessel diameter because of the limited number density of tracer particles under in vivo conditions. Thus, the μ-PTV technique alone is limited in measuring unsteady blood flows that fluctuate irregularly due to the heart beating and muscle movement in surrounding tissues. In this study, a new hybrid PIV-PTV technique was established by combining PTV and particle image velocimetry (PIV) techniques to resolve the drawbacks of the μ-PTV method in measuring blood flow in microvessels under in vivo conditions. Images of red blood cells (RBCs) and fluorescent particles in rat mesenteric vessels were obtained simultaneously. Temporal variations of the centerline blood velocity were monitored using a fast Fourier transform-based cross-correlation PIV method. The fluorescence particle images were analyzed using the μ-PTV technique to extract the spatial distribution of the velocity vectors. Data from the μ-PTV and PIV methods were combined to obtain a better estimate of the velocity profile in actual blood flow. This technique will be useful in investigating hemodynamics in microcirculation by measuring unsteady irregular blood flows more accurately.

  15. Vector analysis

    CERN Document Server

    Brand, Louis

    2006-01-01

    The use of vectors not only simplifies treatments of differential geometry, mechanics, hydrodynamics, and electrodynamics, but also makes mathematical and physical concepts more tangible and easy to grasp. This text for undergraduates was designed as a short introductory course to give students the tools of vector algebra and calculus, as well as a brief glimpse into these subjects' manifold applications. The applications are developed to the extent that the uses of the potential function, both scalar and vector, are fully illustrated. Moreover, the basic postulates of vector analysis are brou

  16. Dogs with hearth diseases causing turbulent high-velocity blood flow have changes in patelet function and von Willebrand factor multimer distribution

    DEFF Research Database (Denmark)

    Tarnow, Inge; Kristensen, Annemarie Thuri; Olsen, Lisbeth Høier

    2005-01-01

    and echocardiography were performed in all dogs. PFA100 closure times (the ability of platelets to occlude a hole in a membrane at high shear rates), platelet activation markers (plasma thromboxane B2 concentration, platelet surface P-selectin expression), platelet aggregation (in whole blood and platelet-rich plasma...

  17. Study of regional left ventricular longitudinal function in fetuses with gestational diabetes mellitus by velocity vector imaging%速度向量成像技术评价妊娠期糖尿病胎儿左室心肌节段功能的探讨

    Institute of Scientific and Technical Information of China (English)

    王小艳; 周启昌; 蒲大容; 彭清海; 曾施; 谭宜

    2011-01-01

    目的 探讨VVI技术检测妊娠期糖尿病胎儿左室心肌6节段功能的临床意义.方法 采集98例妊娠期糖尿病胎儿和135例正常对照组胎儿四腔观,利用VVI软件测量左室各节段收缩期峰值速度(Vs)、舒张期峰值速度(Vd)、收缩期峰值应变(S)、收缩期应变率(SRs)和舒张期应变率(SRd).结果 233例胎儿中207例被成功分析.妊娠期糖尿病组胎儿Vs、Vd随孕周的增加而增大(P<0.05),基底段、中间段、心尖段心肌的Vs、Vd依次逐渐减低(P <0.05).32+0周后妊娠期糖尿病胎儿Vs、28+0周后Vd、24+0周后S、SRs、SRd均较相应的正常胎儿组减低(P<0.05).结论 VVI技术可以检测妊娠期糖尿病胎儿左室长轴6节段心肌功能的变化.%Objective To investigate the clinical value of velocity vector imaging in the assessment of regional left ventricular longitudinal myocardial function in fetuses with gestational diabetes mellitus (GDM). Methods Digital dynamic four-chamber views of 98 fetuses with GDM and 135 normal fetuses were collected and analyzed using velocity vector imaging. The regional tissue velocity, strain and strain rate of the interventricular septum and left lateral wall were measured in systole and diastole. Results Two hundred and seven of 233 cases were analyzed successfully. Systolic velocity(Vs) and diastolic velocity(Vd)were age-dependent, Vs and Vd were both gradually decreased from the basal segment to the apical segment in the left ventricle( P <0. 05). The Va after 32+0 weeks and Vd after 28+0 weeks and systolic strain(S),systolic strain rate(SRs) and diastolic strain rate(SRd) in left ventricle of fetuses with GDM after 24+0weeks were obviously lower than the corresponding parameters of normal fetuses ( P <0. 05). Conclusions Velocity vector imaging can evaluate the fetal regional left ventricular longitudinal myocardial function.

  18. Volume Tracking: A new method for quantitative assessment and visualization of intracardiac blood flow from three-dimensional, time-resolved, three-component magnetic resonance velocity mapping

    Directory of Open Access Journals (Sweden)

    Arheden Håkan

    2011-04-01

    Full Text Available Abstract Background Functional and morphological changes of the heart influence blood flow patterns. Therefore, flow patterns may carry diagnostic and prognostic information. Three-dimensional, time-resolved, three-directional phase contrast cardiovascular magnetic resonance (4D PC-CMR can image flow patterns with unique detail, and using new flow visualization methods may lead to new insights. The aim of this study is to present and validate a novel visualization method with a quantitative potential for blood flow from 4D PC-CMR, called Volume Tracking, and investigate if Volume Tracking complements particle tracing, the most common visualization method used today. Methods Eight healthy volunteers and one patient with a large apical left ventricular aneurysm underwent 4D PC-CMR flow imaging of the whole heart. Volume Tracking and particle tracing visualizations were compared visually side-by-side in a visualization software package. To validate Volume Tracking, the number of particle traces that agreed with the Volume Tracking visualizations was counted and expressed as a percentage of total released particles in mid-diastole and end-diastole respectively. Two independent observers described blood flow patterns in the left ventricle using Volume Tracking visualizations. Results Volume Tracking was feasible in all eight healthy volunteers and in the patient. Visually, Volume Tracking and particle tracing are complementary methods, showing different aspects of the flow. When validated against particle tracing, on average 90.5% and 87.8% of the particles agreed with the Volume Tracking surface in mid-diastole and end-diastole respectively. Inflow patterns in the left ventricle varied between the subjects, with excellent agreement between observers. The left ventricular inflow pattern in the patient differed from the healthy subjects. Conclusion Volume Tracking is a new visualization method for blood flow measured by 4D PC-CMR. Volume Tracking

  19. Absolute Geostrophic Velocity Inverted from the Environmental Working Group (EWG) Joint U.S.-Russian Atlas of the Arctic Ocean with the P-Vector Method (NCEI Accession 0156424)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset (called EWG-V) comprises 3D gridded climatological fields of absolute geostrophic velocity inverted from the Environmental Working Group (EWG) Joint...

  20. Cloning vector

    Science.gov (United States)

    Guilfoyle, Richard A.; Smith, Lloyd M.

    1994-01-01

    A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.

  1. Towards a Proteomic Catalogue and Differential Annotation of Salivary Gland Proteins in Blood Fed Malaria Vector Anopheles culicifacies by Mass Spectrometry.

    Science.gov (United States)

    Rawal, Ritu; Vijay, Sonam; Kadian, Kavita; Singh, Jagbir; Pande, Veena; Sharma, Arun

    2016-01-01

    In order to understand the importance of functional proteins in mosquito behavior, following blood meal, a baseline proteomic dataset is essential for providing insights into the physiology of blood feeding. Therefore, in this study as first step, in solution and 1-D electrophoresis digestion approach combined with tandem mass spectrometry (nano LC-MS/MS) and computational bioinformatics for data mining was used to prepare a baseline proteomic catalogue of salivary gland proteins of sugar fed An. culicifacies mosquitoes. A total of 106 proteins were identified and analyzed by SEQUEST algorithm against mosquito protein database from Uniprot/NCBI. Importantly, D7r1, D7r2, D7r4, salivary apyrase, anti-platelet protein, calreticulin, antigen 5 family proteins were identified and grouped on the basis of biological and functional roles. Secondly, differential protein expression and annotations between salivary glands of sugar fed vs blood fed mosquitoes was analyzed using 2-Delectrophoresis combined with MALDI-TOF mass spectrometry. The alterations in the differential expression of total 38 proteins was observed out of which 29 proteins like beclin-1, phosphorylating proteins, heme oxygenase 1, ferritin, apoptotic proteins, coagulation and immunity like, serine proteases, serpins, c-type lectin and protein in regulation of blood feeding behavior were found to be up regulated while 9 proteins related to blood feeding, juvenile hormone epoxide hydrolase ii, odorant binding proteins and energy metabolic enzymes were found to be down regulated. To our knowledge, this study provides a first time baseline proteomic dataset and functional annotations of An. culicifacies salivary gland proteins that may be involved during the blood feeding. Identification of differential salivary proteins between sugar fed and blood fed mosquitoes and their plausible role may provide insights into the physiological processes associated with feeding behavior and sporozoite transmission during the

  2. Towards a Proteomic Catalogue and Differential Annotation of Salivary Gland Proteins in Blood Fed Malaria Vector Anopheles culicifacies by Mass Spectrometry

    Science.gov (United States)

    Rawal, Ritu; Vijay, Sonam; Kadian, Kavita; Singh, Jagbir; Pande, Veena; Sharma, Arun

    2016-01-01

    In order to understand the importance of functional proteins in mosquito behavior, following blood meal, a baseline proteomic dataset is essential for providing insights into the physiology of blood feeding. Therefore, in this study as first step, in solution and 1-D electrophoresis digestion approach combined with tandem mass spectrometry (nano LC-MS/MS) and computational bioinformatics for data mining was used to prepare a baseline proteomic catalogue of salivary gland proteins of sugar fed An. culicifacies mosquitoes. A total of 106 proteins were identified and analyzed by SEQUEST algorithm against mosquito protein database from Uniprot/NCBI. Importantly, D7r1, D7r2, D7r4, salivary apyrase, anti-platelet protein, calreticulin, antigen 5 family proteins were identified and grouped on the basis of biological and functional roles. Secondly, differential protein expression and annotations between salivary glands of sugar fed vs blood fed mosquitoes was analyzed using 2-Delectrophoresis combined with MALDI-TOF mass spectrometry. The alterations in the differential expression of total 38 proteins was observed out of which 29 proteins like beclin-1, phosphorylating proteins, heme oxygenase 1, ferritin, apoptotic proteins, coagulation and immunity like, serine proteases, serpins, c-type lectin and protein in regulation of blood feeding behavior were found to be up regulated while 9 proteins related to blood feeding, juvenile hormone epoxide hydrolase ii, odorant binding proteins and energy metabolic enzymes were found to be down regulated. To our knowledge, this study provides a first time baseline proteomic dataset and functional annotations of An. culicifacies salivary gland proteins that may be involved during the blood feeding. Identification of differential salivary proteins between sugar fed and blood fed mosquitoes and their plausible role may provide insights into the physiological processes associated with feeding behavior and sporozoite transmission during the

  3. Error analysis and compensation of blood viscometer rotating cone angular velocity%血液粘度仪旋转锥体角速度误差分析与补偿

    Institute of Scientific and Technical Information of China (English)

    唐俊铨; 田学隆

    2011-01-01

    剪切池内旋转锥体的角速度是新型锥板式血液粘度仪的主要信息源,其精度取决于光电传感器和齿形盘.分析了光电传感器的点光源特性和齿形盘的周期性摆动及其加工精度导致的角度误差.针对锥体角速度的单调递减特性、角度误差在单转内的随机性及整个测量过程中呈周期性,采用有理三次样条插值算法对角速度误差进行补偿.实验结果表明:该方法可提高角速度的测量精度,降低传感器的生产成本.%The angular velocity of rotating cone in shear-pool is the main information source of a cone-plate blood viscometer,and its precision depends on the photoelectric sensor and fluted disc. The error sources of angular velocity device are analyzed, that is, the pointolite characteristic of photoelectric sensor, and the angular error due to the cyclical swing and the machining inaccuracy of fluted disc. Since the cone angular velocity is monotone decreasing and the angular error is random in one cycle but is cyclical variation during the whole detecting process,a rational cubic spline interpolation algorithm is adopted to decrease the angular error. Experimental results show that this method can improve the precision of angular velocity and reduce the production cost of sensor.

  4. Effect of eye acupuncture on cerebral blood flow and velocity in rats with ischemia-reperfusion%眼针对大鼠脑缺血再灌注脑血流量及速度影响

    Institute of Scientific and Technical Information of China (English)

    吴翊馨; 张海平; 苏胜林

    2013-01-01

    Objective To observe the effect of eye acupuncture on cerebral blood flow and velocity in rats with cerebral ischemia reperfusion(ICRI) and to explore the mechanisms of eye acupunture treatment to cerebral ischencic diseases.Methods Laser Doppler microcirculation measurement instrument was used to measure blood flow and velocity of cerebnal cortex in rats 24 hours after cerebral ischemia.The structural changes in the capillary loops of the cortex was observed with electron microscope.Results The blood flow of cerebral cortex was 63.28 ± 8.84 PU for ischemic model rats and 169.39 ± 19.89 for the model rats with eye acupuncture,and the blood flow velocity was 19.98 ±6.75 mm/s for the model rats and 57.43 ± 28.54 mm/s for the model rats with eye acupucture,respectively,with significant defferences between the two groups(P < 0.01 for all).The ultrastructure of cerebral cortex capillary was normal for model rats with eye acupuntrre but necrosis and atrophy of capillary endothelial cells were observed in cerebral ischemic model rats.Conclusion Eye acupucture can increase blood flow and velocity of cortex tissue in rats with ICRI and improve ultrastructure of the capillary endothelial cells in rats with ICRI.%目的 观察眼针对脑缺血再灌注模型(CIRI)大鼠脑皮层血流量及流速影响,探讨眼针治疗脑缺血性疾病的可能机制.方法 运用激光多普勒微循环测量仪检测缺血24 h模型大鼠大脑皮层组织血流量及血流速度;观察电镜下毛细血管管壁的结构变化.结果 模型组与眼针组大鼠大脑皮层组织血流量与血流速度分别为(63.28 ±8.84)、(169.38±19.89) PU和(18.98 ±6.75)、(57.43±28.84) mm/s,与模型组比较,眼针组大鼠大脑皮层组织的血流量明显升高、血流速度明显加快(P<0.01);眼针组大鼠大脑皮层毛细血管的超微结构基本正常,模型组内皮细胞坏死、萎缩.结论 眼针能够增加ICRI模型大鼠脑皮层组织血流量,提高血流

  5. Quantification of ultrasound correlation-based flow velocity mapping and edge velocity gradient measurement.

    Science.gov (United States)

    Park, Dae Woo; Kruger, Grant H; Rubin, Jonathan M; Hamilton, James; Gottschalk, Paul; Dodde, Robert E; Shih, Albert J; Weitzel, William F

    2013-10-01

    This study investigated the use of ultrasound speckle decorrelation- and correlation-based lateral speckle-tracking methods for transverse and longitudinal blood velocity profile measurement, respectively. By studying the blood velocity gradient at the vessel wall, vascular wall shear stress, which is important in vascular physiology as well as the pathophysiologic mechanisms of vascular diseases, can be obtained. Decorrelation-based blood velocity profile measurement transverse to the flow direction is a novel approach, which provides advantages for vascular wall shear stress measurement over longitudinal blood velocity measurement methods. Blood flow velocity profiles are obtained from measurements of frame-to-frame decorrelation. In this research, both decorrelation and lateral speckle-tracking flow estimation methods were compared with Poiseuille theory over physiologic flows ranging from 50 to 1000 mm/s. The decorrelation flow velocity measurement method demonstrated more accurate prediction of the flow velocity gradient at the wall edge than the correlation-based lateral speckle-tracking method. The novelty of this study is that speckle decorrelation-based flow velocity measurements determine the blood velocity across a vessel. In addition, speckle decorrelation-based flow velocity measurements have higher axial spatial resolution than Doppler ultrasound measurements to enable more accurate measurement of blood velocity near a vessel wall and determine the physiologically important wall shear.

  6. Problems and worked solutions in vector analysis

    CERN Document Server

    Shorter, LR

    2014-01-01

    ""A handy book like this,"" noted The Mathematical Gazette, ""will fill a great want."" Devoted to fully worked out examples, this unique text constitutes a self-contained introductory course in vector analysis for undergraduate and graduate students of applied mathematics.Opening chapters define vector addition and subtraction, show how to resolve and determine the direction of two or more vectors, and explain systems of coordinates, vector equations of a plane and straight line, relative velocity and acceleration, and infinitely small vectors. The following chapters deal with scalar and vect

  7. Blood meal analysis, flavivirus screening, and in!uence of meteorological variables on the dynamics of potential mosquito vectors of West Nile virus in northern Italy

    DEFF Research Database (Denmark)

    Roiz, David; Vazquez, Ana; Rosà, Roberto;

    2012-01-01

    . Analysis of blood meals showed that Culex pipiens fed mainly on blackbirds (Turdus merula) and house sparrows (Passer domesticus), while Culex hortensis fed strictly on lizards. The abundance of Cx. pipiens females correlated positively with mean temperature and negatively with rainfall (one to four weeks...

  8. Sodium Velocity Maps on Mercury

    Science.gov (United States)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  9. Vector geometry

    CERN Document Server

    Robinson, Gilbert de B

    2011-01-01

    This brief undergraduate-level text by a prominent Cambridge-educated mathematician explores the relationship between algebra and geometry. An elementary course in plane geometry is the sole requirement for Gilbert de B. Robinson's text, which is the result of several years of teaching and learning the most effective methods from discussions with students. Topics include lines and planes, determinants and linear equations, matrices, groups and linear transformations, and vectors and vector spaces. Additional subjects range from conics and quadrics to homogeneous coordinates and projective geom

  10. Velocidade da onda de pulso, pressão arterial e adipocitocinas em adultos jovens: estudo do Rio de Janeiro Pulse wave velocity, blood pressure and adipocytokines in young adults: the Rio de Janeiro study

    Directory of Open Access Journals (Sweden)

    Oswaldo Luiz Pizzi

    2012-01-01

    identificação do acometimento vascular nessa faixa etária.BACKGROUND: Data on noninvasive vascular assessment and their association with cardiovascular risk variables are scarce in young individuals. OBJECTIVE: To evaluate the association between pulse wave velocity and blood pressure, anthropometric and metabolic variables, including adipocytokines, in young adults. METHODS: A total of 96 individuals aged 26 to 35 years (mean 30.09 ± 1.92; 51 males were assessed in the Rio de Janeiro study. Pulse wave velocity (Complior method, blood pressure, body mass index, glucose, lipid profile, leptin, insulin, adiponectin and insulin resistance index (HOMA-IR were analyzed. Subjects were stratified into three groups according to the PWV tertile for each gender. RESULTS: The group with the highest pulse wave velocity (PWV tertile showed higher mean systolic and diastolic blood pressure, mean blood pressure, body mass index, insulin, and HOMA-IR, as well as lower mean adiponectin; higher prevalence of diabetes mellitus/glucose intolerance and hyperinsulinemia. There was a significant positive correlation of PWV with systolic blood pressure, diastolic blood pressure, pulse pressure and mean blood pressure, body mass index, and LDL-cholesterol, and a negative correlation with HDL-cholesterol and adiponectin. In the multiple regression model, after adjustment of HDL-cholesterol, LDL-cholesterol and adiponectin for gender, age, body mass index and mean blood pressure, only the male gender and mean blood pressure remained significantly correlated with PWV. CONCLUSION: PWV in young adults showed a significant association with cardiovascular risk variables, especially in the male gender, and mean blood pressure as important determinant variables. The findings suggest that PWV measurement can be useful for the identification of vascular impairment in this age group.

  11. Velocidade da onda de pulso, pressão arterial e adipocitocinas em adultos jovens: estudo do Rio de Janeiro Pulse wave velocity, blood pressure and adipocytokines in young adults: the Rio de Janeiro study

    Directory of Open Access Journals (Sweden)

    Oswaldo Luiz Pizzi

    2013-01-01

    identificação do acometimento vascular nessa faixa etária.BACKGROUND: Data on noninvasive vascular assessment and their association with cardiovascular risk variables are scarce in young individuals. OBJECTIVE: To evaluate the association between pulse wave velocity and blood pressure, anthropometric and metabolic variables, including adipocytokines, in young adults. METHODS: A total of 96 individuals aged 26 to 35 years (mean 30.09 ± 1.92; 51 males were assessed in the Rio de Janeiro study. Pulse wave velocity (Complior method, blood pressure, body mass index, glucose, lipid profile, leptin, insulin, adiponectin and insulin resistance index (HOMA-IR were analyzed. Subjects were stratified into three groups according to the PWV tertile for each gender. RESULTS: The group with the highest pulse wave velocity (PWV tertile showed higher mean systolic and diastolic blood pressure, mean blood pressure, body mass index, insulin, and HOMA-IR, as well as lower mean adiponectin; higher prevalence of diabetes mellitus/glucose intolerance and hyperinsulinemia. There was a significant positive correlation of PWV with systolic blood pressure, diastolic blood pressure, pulse pressure and mean blood pressure, body mass index, and LDL-cholesterol, and a negative correlation with HDL-cholesterol and adiponectin. In the multiple regression model, after adjustment of HDL-cholesterol, LDL-cholesterol and adiponectin for gender, age, body mass index and mean blood pressure, only the male gender and mean blood pressure remained significantly correlated with PWV. CONCLUSION: PWV in young adults showed a significant association with cardiovascular risk variables, especially in the male gender, and mean blood pressure as important determinant variables. The findings suggest that PWV measurement can be useful for the identification of vascular impairment in this age group.

  12. Notes from 1999 on computational algorithm of the Local Wave-Vector (LWV) model for the dynamical evolution of the second-rank velocity correlation tensor starting from the mean-flow-coupled Navier-Stokes equations

    Energy Technology Data Exchange (ETDEWEB)

    Zemach, Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kurien, Susan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-14

    These notes present an account of the Local Wave Vector (LWV) model of a turbulent flow defined throughout physical space. The previously-developed Local Wave Number (LWN) model is taken as a point of departure. Some general properties of turbulent fields and appropriate notation are given first. The LWV model is presently restricted to incompressible flows and the incompressibility assumption is introduced at an early point in the discussion. The assumption that the turbulence is homogeneous is also introduced early on. This assumption can be relaxed by generalizing the space diffusion terms of LWN, but the present discussion is focused on a modeling of homogeneous turbulence.

  13. 老年原发性高血压患者晨峰与脉搏波传导速度相关性研究%Association between morning blood pressure surge and pulse wave velocity in elderly hypertensive subjects

    Institute of Scientific and Technical Information of China (English)

    胡小亮; 路方红; 刘振东; 赵颖馨; 孙尚文; 王舒健; 潘慧; 李俊

    2011-01-01

    目的 探讨老年高血压患者血压晨峰与颈桡动脉脉搏波传导速度(crPWV)的相关性.方法 选择老年原发性高血压患者159例,根据24 h动态血压结果,将患者分为晨峰组(95例)和非晨峰组(64例).2组行crPWV检测,并测血生化.结果 晨峰组crPWV明显高于非晨峰组[(11.5±1.7)m/s vs(9.1±1.6)m/s,P<0.01].crPWV与血压晨峰(r=0.787,P<0.01)、24 h收缩压(r=0.649,P<0.01)、年龄(r=0.437,P<0.01)、空腹血糖(r=0.293,P<0.05)及LDL-c(r=0.354,P<0.05)呈正相关;以crPWV为应变量,年龄、高血压病程、体重指数、空腹血糖、24 h收缩压及舒张压、LDL-C、TC、TG、HDL-C、血压晨峰为自变量,进行多元线性逐步回归分析,血压晨峰、24 h收缩压、年龄为crPWV独立影响因素.结论 血压晨峰与动脉粥样硬化密切相关.%objective To investigate the association between morning blood pressure (MBPS) and carotid-radial pulse wave velocity(crPWV) ,in elderly patients with essential hypertension. Method According to the results of 24 h ambulatory blood pressure monitoring, 159 patients were divided in to the morning surge group(MBPS group,n= 95) and non-morning blood pressure surge group(nMBPS group, n= 64). Carotid-radial pulse wave velocity, blood glucose and lipid profiles were recorded. Results The crPWV of the MBPS group was significantly higher than that of the nMBPS group[(11.5±1.7)m/s vs (9. 1±1. 6)m/s,P<0. 01]. Pearson relation analysis showed that crPWV level positively correlated with MBPS(r=0. 787,P<0. 01),the average of 24 h SBP (r=0. 649,P<0. 01) ,age(r=0. 437,P<0. 01),FPG(r=0. 293,P<0. 05) and LDL-C(r=0. 354, P<0. 05); Multiple linear regression showed that MBPS were significant and independent factors for crPWV in elderly patients with essential hypertension. Conclusion The study showed that MBPS was closely related with atherosclerosis in patients with essential hypertension,suggesting it is justified for concurrent inhibition of morning blood

  14. Acoustic vector sensor signal processing

    Institute of Scientific and Technical Information of China (English)

    SUN Guiqing; LI Qihu; ZHANG Bin

    2006-01-01

    Acoustic vector sensor simultaneously, colocately and directly measures orthogonal components of particle velocity as well as pressure at single point in acoustic field so that is possible to improve performance of traditional underwater acoustic measurement devices or detection systems and extends new ideas for solving practical underwater acoustic engineering problems. Although acoustic vector sensor history of appearing in underwater acoustic area is no long, but with huge and potential military demands, acoustic vector sensor has strong development trend in last decade, it is evolving into a one of important underwater acoustic technology. Under this background, we try to review recent progress in study on acoustic vector sensor signal processing, such as signal detection, DOA estimation, beamforming, and so on.

  15. Optimization of gene transfer into primitive human hematopoietic cells of granulocyte-colony stimulating factor-mobilized peripheral blood using low-dose cytokines and comparison of a gibbon ape leukemia virus versus an RD114-pseudotyped retroviral vector.

    Science.gov (United States)

    van der Loo, Johannes C M; Liu, B L; Goldman, A I; Buckley, S M; Chrudimsky, K S

    2002-07-20

    Primitive human hematopoietic cells in granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood (MPB) are more difficult to transduce compared to cells from umbilical cord blood. Based on the hypothesis that MPB cells may require different stimulation for efficient retroviral infection, we compared several culture conditions known to induce cycling of primitive hematopoietic cells. MPB-derived CD34(+) cells were stimulated in the presence or absence of the murine fetal liver cell line AFT024 in trans-wells with G-CSF, stem cell factor (SCF), and thrombopoietin (TPO) (G/S/T; 100 ng/ml) or Flt3-L, SCF, interleukin (IL)-7, and TPO (F/S/7/T; 10-20 ng/ml), and transduced using a GaLV-pseudotyped retroviral vector expressing the enhanced green fluorescence protein (eGFP). Compared to cultures without stroma, the presence of AFT024 increased the number of transduced colony-forming cells (CFC) by 3.5-fold (with G/S/T), long-term culture-initiating cells (LTC-IC) by 4.6-fold (with F/S/7/T), and nonobese diabetic/severe immunodeficiency disease (NOD/SCID)-repopulating cells (SRC) by 6.8-fold (with F/S/7/T). Similar numbers of long-term culture-initiating cells (LTC-IC) and SRC could be transduced using AFT024-conditioned medium (AFT-CM) or a defined medium that had been supplemented with factors identified in AFT-CM. Finally, using our best condition based on transduction with the gibbon ape leukemia virus (GaLV)-pseudotyped vector, we demonstrate a 33-fold higher level of gene transfer (p optimized protocol with low doses of cytokines, and transduction with an RD114 compared to a GaLV-pseudotyped retroviral vector, the overall number of transduced cells in NOD/SCID mice could be improved 144-fold, with a gene-transfer efficiency in SRC of 16.3% (13.3-19.9; n = 6).

  16. 孤立性颈动脉粥样硬化斑块内膜长轴切面力学状态的初步超声研究%Preliminary longitudinal mechanical pattern study of the isolated carotid atherosclerotic plaque intima using velocity vector imaging

    Institute of Scientific and Technical Information of China (English)

    岳文胜; 尹立雪; 王珊; 邓燕; 左明良; 李爽; 余洋; 罗安果

    2008-01-01

    Objective To evaluate the mechanical homogeneity pattern of isolated carotid atherosclerotic plaque intima on longitudinal axis view using ultrasonic velocity vector imaging.Methods Fourty six patients with 48 isolated plaques were undergone the high frequency ultrasound scanning,the real-time two-dimensional longitudinal-axis gray scale view at the maximal thickness of the plaque was obtained in three complete cardiac cycles.A dedicated velocity vector imaging(ⅤⅤⅠ)workstation was used for the off-line dynamic two-dimensional gray-scale image analysis and mechanics parameter(i.e.,the peak strain and the absolute difference of the peak strain)assessment at the sites of the upper,middle and down stream separately.The length and direction distribution of the velocity vectors at the carotid atherosclerotic plaque intima were observed.Wilcoxon test was utilized for the comparison of the peak strain and the absolute difference of the peak strain between two sites.Results The chaos phenomenon of velocity vector distribution at the sites of plaque intima occurred significantly differed from those uniform velocity vectors at the reference sites.According to the two groups of the higher strain value side and the lower strain value side on the upper stream and the down stream of the plaque intima,the peak strain at the higher strain value side was significantly higher than the lower strain value side(P=0.000).There was a significantly difference between the absolute difference of peak strain from the higher strain value side to the middle stream point of the plaque intima and the absolute difference of peak strain from the lower strain value side to the higher strain value side of the plaque intima(P<0.017).Conclusions The length and direction distribution of velocity vectors of the isolated carotid atherosclerotic plaque intima on longitudinal axis view are uneven,the mechanical heterogeneity pattern exists at the plaque intima and could be visualized and

  17. 应用心肌造影超声心动图结合速度向量成像对糖尿病大鼠心肌微循环与收缩功能障碍的相关性研究%Relationship between myocardial perfusion impairment and dysfunction in diabetic rats using myocardial contrast echocardiography and velocity vector imaging

    Institute of Scientific and Technical Information of China (English)

    卫张蕊; 张军; 张海滨; 苏海砾; 施红; 朱霆; 朱永胜

    2012-01-01

    目的 应用心肌造影超声心动图(MCE)结合速度向量成像(VVI)技术研究糖尿病(DM)大鼠左室心肌微循环障碍与心肌收缩功能损伤之间的相关关系.方法 雄性SD大鼠23只,腹腔注射链脲菌素复制DM模型,另23只体质量匹配的雄性SD大鼠腹腔注射等量生理盐水作为对照.分别在静息状态和潘生丁负荷后,对两组大鼠(12周)乳头肌水平左室短轴行MCE和VVI检查,分别测定心肌血流量(MBF)、心肌血流储备(MFR)、收缩期最大圆周应变率(SRc)及其储备,分析MBF/MFR与SRc/SRc储备之间是否存在相关关系.结果 DM组大鼠的SRc、SRc储备、MBF及MFR均较对照组显著减低.DM组大鼠SRc与MBF之间没有明显相关性,而SR.储备与MFR之间呈现显著的负相关.结论 静息状态下,心肌血流量的降低并不是圆周应变率降低的主要决定因素,而潘生丁负荷后,心肌血流储备的降低可能是心肌圆周应变率储备降低的主要决定因素.%Objective To investigate whether myocardial dysfunction and perfusion impairment had happened in diabetes mellitus(DM)rats,and to assess the relationship between them by using myocardial contrast echocardiography(MCE)and velocity vector imaging(VVI).Methods MCE and VVI were performed from the short-axis views of the mid-left ventricular level both at rest and after dipyridamole stress in control rats and DM rafs(12 weeks after induction with streptozotocin).MCE-derived myocardial blood flow(MBF)and myocardial flow reserve(MFR)and VVI-derived circumferential strain rate(SRc)and SRc reserve were obtained.Results SRc(absolute value)and MBF in the DM group were significantly lower than those in the control group at rest(P =0.03 for SRc and P =0.005 for MBF).SRc reserve and MFR in the DM group were significantly lower than those in the control group after dipyridamole stress (P =0.000 for SRc reserve and P =0.014 for MFR).There was no significant correlation between SRc and MBF at rest in the

  18. Evaluation of regional left ventricular longitudinal function in 151 normal fetuses using velocity vector imaging%速度向量成像技术检测胎儿心肌节段功能的临床研究

    Institute of Scientific and Technical Information of China (English)

    彭清海; 周启昌; 曾施; 田蕾琪; 章鸣; 谭宜

    2008-01-01

    Objective To investigate the clinical value of VVI assessment normal fetal segmental myocardial performance and to establish a nomogram of normal fetus.Methods Digital dynamic fourchamber imaging of 151 healthy fetus(divided 5 groups according to gestation)were collected,then the longitudinal velocity,strain and strain rate of interventricular septal and left lateral wall were measured in systolic and diastolic period respectively.Results Normal systolic and diastolic values for tissue velocitv.strain,and strain rate were established.Tissue velocity was age dependent,whereas strain and strain rate were stable throughout gestation(P>0.05).Tissue velocity was gradually decreased from the base segment to the apical segment(P<0.01),whereas strain and strain rate were stable among all segments in every group(P>0.05).Conclusions Fetal myocardial velocity,strain,and strain rate measuraments are easy to obtain and reproducible,VVI is a novel noninvasive tool to assess quantitatively and objectivelv regional systolic and diastolic function in fetal heart,it is providing another useful modality for evaluating cardiac function.%目的 探讨速度向量成像技术检测正常胎儿左室心肌节段功能的临床应用价值.方法 应用Sequoia 512彩色多普勒超声诊断系统,在四腔心观采集151例孕18~40周的正常胎儿超声图像,用心肌速度向量软件分析左室后间隔和侧壁心肌长轴方向收缩期和舒张期峰值速度、应变及应变率.结果 各组基底段至心尖段心肌速度逐渐减低(P<0.01),各节段心肌应变和应变率差异无统计学意义(P>0.05).收缩期和舒张期峰值速度随孕周的增加而增大(P<0.01),而应变、应变率随孕周增加差异无统计学意义(P>0.05).结论 速度向量成像技术不受声束角度、胎方位、胎心率的影响,能够无创客观地定量评价胎儿左室长轴心肌节段舒缩功能,为临床检测胎儿心脏节段功能提供了又一有效方法 .

  19. Blood Types

    Science.gov (United States)

    ... maternity. Learn About Blood Blood Facts and Statistics Blood Components Whole Blood and Red Blood Cells Platelets Plasma ... About Blood Blood Facts and Statistics Blood Types Blood Components What Happens to Donated Blood Blood and Diversity ...

  20. Emerging vector borne diseases – incidence through vectors

    Directory of Open Access Journals (Sweden)

    Sara eSavic

    2014-12-01

    Full Text Available Vector borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowdays, in intercontinetal countries, there is a struggle with emerging diseases which have found their way to appear through vectors. Vector borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector borne infectious diseases and disease outbreaks. It could affect the range and popultion of pathogens, host and vectors, transmission season, etc. Reliable surveilance for diseases that are most likely to emerge is required. Canine vector borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, erlichiosis, leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fudamental role at primeraly prevention and then treatment of vector borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases.During a four year period, from 2009-2013, a total number of 551 dog samples were analysed for vector borne diseases (borreliosis, babesiosis, erlichiosis, anaplasmosis, dirofilariosis and leishmaniasis in routine laboratory work. The analysis were done by serological tests – ELISA for borreliosis, dirofilariosis and leishmaniasis, modified Knott test for dirofilariosis and blood smear for babesiosis, erlichiosis and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on avarege more then half of the samples

  1. Assessment of radial movement of left ventricle with velocity vector imaging in patients with dilated cardiomyopathy%速度向量成像技术评价扩张型心肌病患者径向室壁运动

    Institute of Scientific and Technical Information of China (English)

    王玮; 施仲伟; 胡厚达; 许燕; 张凤如

    2010-01-01

    Objective To assess the radial systolic function of left ventricle(LV) in patients with dilated cardiomyopathy(DCM) by velocity vector imaging(VVI).Methods Sixteen patients with DCM and twenty control subjects were detected by VVI.VVI data were collected from the six basal segments and six mid segments in parastenal LV short axis views.The radial systolic velocity(V) ,strain(ε) ,strain rate(SR),the time to peak systolic velocity(PTV) and the time to maximum strain(PTε) were measured with special software.The differene of the earliest and the latest time to peak velocity(T-max) and the standard deviation of time to peak velocity(T-SD) of 12 segments were calculated.Results Compared to the controlled group,patients with DCM had significantly lower radial V,ε and SR (P <0.01) in all the 12 segments,significantly longer PTV and PTε (P < 0.05) in most segments, and significantly larger T-max and T-SD (P <0.05).Conclusions VVI is useful to assess the abnormalities in LV radial movement in patients with DCM and could provide more information about regional cardiac function.%目的 应用速度向量成像技术(velocity vector imaging,VVI)评价扩张型心肌病(dilated cardiomyopathy,DCM)径向局部心肌收缩功能和同步性.方法 16例DCM患者和20例对照者进行超声心动图检查,脱机分析左室短轴观中6个基底节段和6个中间节段共12个节段的径向收缩期峰值速度(V)、应变(ε)、应变率(SR)、径向速度达峰时间(PTV)、应变达峰时间(PTε),计算12节段的最早与最晚速度达峰时间差值(T-max)及速度达峰时间标准差(T-SD).结果 ①DCM组各节段的V、ε、SR的平均值均显著低于对照组相应节段(P<0.01);②DCM组的PTV除乳头肌水平前间隔及后间隔外,其余节段均大于对照组(P<0.05),PTε除前间隔二尖瓣水平、乳头肌水平和后间隔二尖瓣水平、乳头肌水平外,其余节段均显著延长(P<0.05);③DCM组的T-max

  2. Relationship Between Ambulatory Blood Pressure Parameters and Pulse Wave Velocity in Prehypertensive Patients%血压正常高值者动脉僵硬度与动态血压参数的关系

    Institute of Scientific and Technical Information of China (English)

    胡小亮; 路方红; 刘振东; 赵颖馨; 孙尚文; 王舒健; 潘慧; 李俊

    2012-01-01

    Aim To investigate the relationship between ambulatory blood pressure parameters and arterial stiffness in prehypertensive patients. Methods According to their blood pressure level, 204 individuals were divided into three groups: namely normotensive controls ( n = 63 ) , prehypertensive participants ( n = 74 ) and hypertensive patients ( n = 67) . The 24 h ambulatory blood pressure monitoring was used to record 24 h systolic blood pressure (24h SBP) , 24 h diastolic blood pressure (24h DBP) , daytime systolic blood pressure (dSBP) , daytime diastolic blood pressure (dDBP) , nighttime systolic blood pressure (nSBP) , nighttime diastolic blood pressure (nDBP) , 24 h pulse pressure (24h PP) , daytime pulse pressure ( dPP) and nighttime pulse pressure ( nPP) . Carotid-radial pulse wave velocity ( crPWV) was obtained by Complior device. Results 24h SBP, 24h DBP, dSBP, dDBP, nSBP, 24h PP, dPP and nPP were higher in prehypertensive than those in normotensives, but lower in hypertensives ( P < 0. 05 or P < 0. 01) . The crPWV in prehy-pertensives was 9. 67 ± 1. 12 m/s, which was higher than that in normotensives (8. 27 ±0. 99 m/s) , but was lower in hypertensives (10. 55 ± 1. 71 m/s) . Multiple linear regression analysis showed that 24h SBP, 24h PP and nSBP were risk factors for crPWV ( B = 0. 385 , 0351 and 0. 247; all P < 0. 05 ) . Conclusion Arterial stiffness had been increased inprehypertensives. 24h SBP, 24h PP and nSBP are the important influencing factors of arterial stiffness.%目的 探讨血压正常高值者动脉僵硬度与动态血压参数的关系.方法 选择理想血压者63例,血压正常高值者74例,高血压者67例.监测所有入选者24h动态血压,应用脉搏波传导速度测定仪测定颈动脉-桡动脉脉搏波传导速度.结果 血压正常高值组24 h收缩压、24 h舒张压、白昼收缩压、白昼舒张压、夜间收缩压、24 h脉压、白昼脉压及夜间脉压均高于理想血压组,低于高血压组(P<0.05或P<0

  3. 速度向量成像技术评价健康成人颈总动脉运动力学的研究%Study on velocity vector imaging in the evaluation of common carotid artery kinetics of healthy adults

    Institute of Scientific and Technical Information of China (English)

    彭云蓉; 齐继连; 范国裕; 钟敏; 肖敏

    2016-01-01

    目的:应用速度向量成像(VVI)技术,探讨健康成人颈总动脉管壁运动特点。方法:将400例正常人按年龄分组,用VVI技术分析各年龄组颈总动脉四个侧壁的收缩期最大峰值运动速度(Vs)、最大切向应变(Smax)及最大切向应变率(SRmax),并进行比较。结果:各年龄组运动及弹力指标比较,差异有统计学意义(P<0.05),各项指标均随年龄增长呈下降趋势。结论:VVI技术可以对不同年龄组颈动脉内膜运动进行可靠的量化评价,提供颈动脉弹性指标的正常参考数据,为临床对血管弹性的评估提供帮助。%Objective:To investigate the characteristics of common carotid artery wall motion in healthy adults using velocity vector imaging(VVI).Methods:400 normal persons were grouped according to age,and we analyzed the peak systolic velocity(Vs), maximum tangential strain(Smax) and maximum tangential strain rate(SRmax) of four side walls of common carotid artery in all age groups by velocity vector imaging,and compared the results.Results:There was significant difference in the exercise and elastic index of all age groups(P<0.05),and each index showed a downward trend with age.Conclusion:VVI technology can be a reliable quantitative evaluation for common carotid artery wall motion of all age groups.It can provide normal reference data of carotid elasticity index,and provide help for clinical evaluation of vascular elasticity.

  4. Vector nematicons

    CERN Document Server

    Horikis, Theodoros P

    2016-01-01

    Families of soliton pairs, namely vector solitons, are found within the context of a coupled nonlocal nonlinear Schrodinger system of equations, as appropriate for modeling beam propagation in nematic liquid crystals. In the focusing case, bright soliton pairs have been found to exist provided their amplitudes satisfy a specific condition. In our analytical approach, focused on the defocusing regime, we rely on a multiscale expansion methods, which reveals the existence of dark-dark and antidark-antidark solitons, obeying an effective Korteweg-de Vries equation, as well as dark-bright solitons, obeying an effective Mel'nikov system. These pairs are discriminated by the sign of a constant that links all physical parameters of the system to the amplitude of the stable continuous wave solutions, and, much like the focusing case, the solitons' amplitudes are linked leading to mutual guiding.

  5. 速度向量成像技术评价心肌梗死患者节段心肌收缩功能%Preliminary Study on Evaluate the Segmental Myocardial Systolic Function of Myocardial Infarction Patients by Velocity Vector Imaging

    Institute of Scientific and Technical Information of China (English)

    孙丽; 叶玉泉; 薛红元; 高丽; 李丽; 焦荣红

    2012-01-01

    Objective: This research compares longitudinal and radial direction movement characteristics by means of Velocity Vector Imaging (VVI), namely, the same segments of normal myocardium, infarted myocardium and non-infarcted myocardium under the resting state. Then evaluates clinical practice value of Velocity vector imaging ( VVI) on coronary heart disease myocardial infarction patients segmental systolic function. Methods: Thirty healthy volunteers and thirty myocardial infarction patients were selected, and we divided them into the normal group and the myocardial infarction group. We select clearly apical four-chamber, apical two-chamber, apical left ventricular long axis views,axis view at papillary level, muscle level and nearly apical level. Quantitative analysis velocity (Vs), strain (S), strain rate (SR) about radial motion of left ventricle anterior septum, anterior, lateral wall, inferior, posterior wall and posterior septal; And longitudinal motion of infarction segments, non-infarcted segments and normal segments from basal segment, middle segment and apical segment. Results: From basal segment to apex, the velocity gradient descent, but the strain rate and strain are the same. Radial velocity, strain rate and strain among the different walls of the left ventricle are the same. Myocardial segmental indicators of WI declined significantly at infracted area then non-infracted segments in its surrounding areas. Conclusions: This research indicates that WI can be used as non-invasive diagnosis of myocardial infarction, which can help to identify or exclude the diagnosis of coronary artery disease myocardial infarction.%目的:应用速度向量成像技术(VVI)比较静息状态下相同节段的正常心肌、梗死心肌及非梗死心肌纵向和径向的运动特点,评价VVI技术对冠心病心肌梗死患者节段心肌收缩功能的临床应用价值.方法:选取健康志愿者30例和心肌梗死患者30例,分为正常组与心肌梗死组.选取

  6. The integration of angular velocity

    CERN Document Server

    Boyle, Michael

    2016-01-01

    A common problem in physics and engineering is determination of the orientation of an object given its angular velocity. When the direction of the angular velocity changes in time, this is a nontrivial problem involving coupled differential equations. Several possible approaches are examined, along with various improvements over previous efforts. These are then evaluated numerically by comparison to a complicated but analytically known rotation that is motivated by the important astrophysical problem of precessing black-hole binaries. It is shown that a straightforward solution directly using quaternions is most efficient and accurate, and that the norm of the quaternion is irrelevant. Integration of the generator of the rotation can also be made roughly as efficient as integration of the rotation. Both methods will typically be twice as efficient naive vector- or matrix-based methods. Implementation by means of standard general-purpose numerical integrators is stable and efficient, so that such problems can ...

  7. 速度向量成像结合6MWT评价慢性肺动脉高压患者右室功能%Assessment of right ventricular function in patients with chronic pulmonary artery hypertension by using velocity vector imaging associating with 6 minutes walking distance test

    Institute of Scientific and Technical Information of China (English)

    侯海军; 李春伶; 刘卫星; 井茹芳; 马秀珠; 董继红; 树俊莲

    2013-01-01

    Objective To assess the change of RV strain and strain rate in patients with chronic pulmonary arterial hypertension by using velocity vector imaging and to investigate the clinical value of velocity vector imaging. Methods 61 patients with chronic pulmonary hypertension(were divided into mild, moderate and severe groups according pulmonary arterial systolic pressure) and 20 age-matched control were enrolled. Right ventricular structure and function parameters were measured and calculated. Myocardial strain and strain rate of RV were determined by VVI software. In addition, all patients of PH and controls underwent 6-minute walking test. Results Patients with varying degrees of pulmonary hypertension had worse RV performance parameters than those of the controls. Peak systolic myocardial strain and strain rate were significantly impaired in patients with PH compared with controls and were most altered in patients with the most severe PH (P<0.05 for all). Systolic strain and strain rate negatively correlated with 6 minitue walk distance(P<0.01). Conclusion The new Velocity Vector Imaging method provides quantitation of global and regional RV function in patients with PH.%目的 利用速度向量成像技术(VVI)评价慢性肺动脉高压患者右室应变和应变率,结合6 min步行距离试验(6MWT)探讨其在临床中的应用价值.方法选取慢性肺动脉高压患者61例,根据肺动脉收缩压分为轻、中、重3组,20例健康志愿者作为对照.每组病人应用VVI技术分析右室的应变和应变率的变化,同时各组都进行6MWT测试.结果肺动脉高压各组右室大小、右室和左室比例、右室容量均较正常对照组明显增加(P <0.05),射血分数明显减低(P <0.05),6 min步行距离(6MWD)明显减少(P <0.05).右室心肌各节段的应变、应变率均较对照组明显降低(P <0.05).右室整体应变和应变率与6MWD成负相关(P <0.01).结论右室应变和应变率是定量地评价肺动脉高压患者右室功能的可靠方法.

  8. 不同收缩压水平对臂踝脉搏波传导速度影响的研究%Effect of different levels of systolic blood pressure on brachial-ankle pulse wave velocity

    Institute of Scientific and Technical Information of China (English)

    王义; 陶杰; 董岩; 陈朔华; 高新颖; 季春鹏; 杨光; 郑瑶; 吴寿岭

    2014-01-01

    Objective To investigate the impact of different levels of systolic blood pressure on brachial-ankle pulse wave velocity(baPWV). Methods A total of 5 852 participants was selected with stratified random sampling from the 101 510 workers of Tangshan Kaiuan Company who had undergone a physical check-up program. 5 222 of them with integral data were recruited into this survey. According to SBP collected during the 2010-2011 health examination program,the population under observation was divided into four groups:optimal SBP(SBP<120 mmHg),high-normal blood pressure Ⅰ period(120 mmHg≤SBP<130 mmHg),high-normal blood pressure Ⅱ period (130 mmHg≤SBP<140 mmHg)and hypertension(SBP≥140 mmHg or SBP<140 mmHg but antihypertensive drug user). Multivariate logistic regression analysis was used to analyze the influence of different levels of systolic blood pressure on baPWV. Results 1)There were 3 132 males and 2 090 females in all the 5 222 participants with an average age of 55.1 years old. Their mean of baPWV was(1 587.57±400.71)cm/s,with the detection rates as 62%(baPWV≥1 400 cm/s). 2)The means of baPWV for the above groups of SBP were 1 322.19,1 456.27,1 544.78 and 1 827.77 cm/s, respectively,with detection rates of baPWV≥1 400 cm/s as 26.4%,49.3%,64.2% and 88.3%, respectively. 3)Results from the Multiple linear regression analysis revealed that β of SBP was 0.40,only ranking second,on age(0.48). 4)Data from the Multiple logistic regression analysis showed that after adjusting for age,gender and other risk factors,when compared to optimal SBP,factors as high-normal blood pressure Ⅰ period、high-normal blood pressure Ⅱ period and hypertension were risk factors for increasing baPWV,with OR values as 2.70(95%CI:2.20-3.32),4.56(95%CI:3.67-5.67)and 13.51(95%CI:10.87-16.78),respectively. Conclusion Higher SBP seemed an independent risk factor for the increase of baPWV.%目的:探讨不同收缩压(SBP)水平对臂踝脉搏波传导速度

  9. Velocity anticipation in the optimal velocity model

    Institute of Scientific and Technical Information of China (English)

    DONG Li-yun; WENG Xu-dan; LI Qing-ding

    2009-01-01

    In this paper,the velocity anticipation in the optimal velocity model (OVM) is investigated.The driver adjusts the velocity of his vehicle by the desired headway,which depends on both instantaneous headway and relative velocity.The effect of relative velocity is measured by a sensitivity function.A specific form of the sensitivity function is supposed and the involved parameters are determined by the both numerical simulation and empirical data.It is shown that inclusion of velocity anticipation enhances the stability of traffic flow.Numerical simulations show a good agreement with empirical data.This model provides a better description of real traffic,including the acceleration process from standing states and the deceleration process approaching a stopped car.

  10. Increasing the Dynamic Range of Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2014-01-01

    In current ultrasound systems the dynamic range of detectable velocities is susceptible to the selected pulse repetition frequency, thus limiting the dynamic range of flow mapping. To establish the feasibility of extending the range of detectable velocities towards low velocity vessels, results...... standard deviations are 1.59% and 6.12%, respectively. The presented method can improve the estimates by synthesizing a lower pulse repetition frequency, thereby increasing the dynamic range of the vector velocity imaging....

  11. Synthesis of star-branched PLA-b-PMPC copolymer micelles as long blood circulation vectors to enhance tumor-targeted delivery of hydrophobic drugs in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Long, Li-xia [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Zhao, Jin, E-mail: zhaojin@tju.edu.cn [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Li, Ke; He, Li-gang; Qian, Xiao-ming; Liu, Chao-yong; Wang, Li-mei; Yang, Xin-qi [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Sun, Jinjin [Department of General Surgery, The Second Hospital of Tianjin Medical University, Tianjin 300211 (China); Ren, Yu [Tianjin Research Center of Basic Medical Science, Tianjin Medical University, Tianjin 300070 (China); Kang, Chun-sheng, E-mail: kang97061@yahoo.com [Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052 (China); Yuan, Xu-bo, E-mail: xbyuan@tju.edu.cn [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China)

    2016-09-01

    Star-branched amphiphilic copolymer nanocarriers with high-density zwitterionic shell show great promise in drug delivery due to their controllable small size and excellent anti-biofouling properties. This gives the hydrophobic cargo with high stability and long blood circulation in vivo. In the present study, star-branched polylactic acid and poly(2-methacryloyloxyethyl phosphorylcholine) copolymers with (AB{sub 3}){sub 3}–type architecture (PLA-b-PMPC{sub 3}){sub 3} were conceived as drug vectors, and the copolymers were synthesized by an “arm-first” approach via the combination of ring opening polymerization (ROP), atom transfer radical polymerization (ATRP) and the click reaction. The self-assembled star-branched copolymer micelles (sCPM) had an average diameter of about 64.5 nm and exhibited an ultra-hydrophilic surface with an ultralow water contact angle of about 12.7°, which efficiently suppressed the adhesion of serum proteins. In vivo experiments showed that the sCPM loading strongly enhanced the blood circulation time of DiI and the plasma half-life of DiI in sCPM was 19.3 h. The relative accumulation concentration in tumor of DiI delivered by sCPM was 2.37-fold higher than that of PLA-PEG, at 4 h after intravenous injection. These results demonstrated that the star-branched copolymer (PLA-b-PMPC{sub 3}){sub 3} is a promising alternative carrier material for intravenous delivery versus classic PEG-modified strategies. - Highlights: • Star-branched amphiphilic copolymer micelles (sCPM) with zwitterionic shells were prepared. • sCPM possess an ultra-hydrophilic surface and thus inhibited the protein absorption. • sCPM can effectively prolong the cargo’s plasma circulation time. • sCPM can enhance the cargo’s passive tumor-targeted delivery.

  12. Trafficking of adeno-associated virus vectors across a model of the blood-brain barrier; a comparative study of transcytosis and transduction using primary human brain endothelial cells.

    Science.gov (United States)

    Merkel, Steven F; Andrews, Allison M; Lutton, Evan M; Mu, Dakai; Hudry, Eloise; Hyman, Bradley T; Maguire, Casey A; Ramirez, Servio H

    2017-01-01

    Developing therapies for central nervous system (CNS) diseases is exceedingly difficult because of the blood-brain barrier (BBB). Notably, emerging technologies may provide promising new options for the treatment of CNS disorders. Adeno-associated virus serotype 9 (AAV9) has been shown to transduce cells in the CNS following intravascular administration in rodents, cats, pigs, and non-human primates. These results suggest that AAV9 is capable of crossing the BBB. However, mechanisms that govern AAV9 transendothelial trafficking at the BBB remain unknown. Furthermore, possibilities that AAV9 may transduce brain endothelial cells or affect BBB integrity still require investigation. Using primary human brain microvascular endothelial cells as a model of the human BBB, we performed transduction and transendothelial trafficking assays comparing AAV9 to AAV2, a serotype that does not cross the BBB or transduce endothelial cells effectively in vivo. Results of our in vitro studies indicate that AAV9 penetrates brain microvascular endothelial cells barriers more effectively than AAV2, but has reduced transduction efficiency. In addition, our data suggest that (i) AAV9 penetrates endothelial barriers through an active, cell-mediated process, and (ii) AAV9 fails to disrupt indicators of BBB integrity such as transendothelial electrical resistance, tight junction protein expression/localization, and inflammatory activation status. Overall, this report shows how human brain endothelial cells configured in BBB models can be utilized for evaluating transendothelial movement and transduction kinetics of various AAV capsids. Importantly, the use of a human in vitro BBB model can provide import insight into the possible effects that candidate AVV gene therapy vectors may have on the status of BBB integrity. Read the Editorial Highlight for this article on page 192.

  13. Current progress of polymeric gene vectors

    Institute of Scientific and Technical Information of China (English)

    ZENG Xuan; SUN YunXia; ZHUO RenXi; ZHANG XianZheng

    2011-01-01

    After over 40 years ot progress,gene therapy provides great opportunities for treating diseases from various genetic disorders,infections and cancers.The success of gene therapy largely depends on the availability of suitable gene vectors.As an attractive alternative to virus-based gene therapy,non-viral gene delivery system has been developed and investigated due to their merits including low immunogenecity,convenient operability,and large-scale manufacturability [1].Because polycations can condense with DNA as a result of electrostatic interactions,form nanosize polyplexes,and protect DNA from degradation by DNase,cationic polymer becomes a major type of non-viral gene delivery vectors (Figure 1) [2].A wide range of polymeric vectors have been developed and investigated in the past decade,such as polyethylenimine (PEI)-based vectors,poly(L-lysine) (PLL)-based vectors,dendrimer-based vectors,polypeptide-based vectors,and chitosan-based vectors [3].However,unlike viral vectors that have the ability to infect host cells and overcome cellular barriers through the course of evolution,nonviral gene vectors exhibit Significantly reduced transfection efficiency as they are obstructed by various extra- and intracellular barriers,including serum proteins in blood stream,cell membrane,endosomal compartment and nuclear membrane [4].

  14. A method for determining critical swimming velocity.

    Science.gov (United States)

    Takahashi, S; Wakayoshi, K; Hayashi, A; Sakaguchi, Y; Kitagawa, K

    2009-02-01

    The purpose of this study was to determine whether the critical swimming velocity (Vcri) estimated by the swimming velocity for a distance of 300 m at maximal effort breaststroke reflects the maximal lactate steady state (MLSS). Twelve trained swimmers swam 50 m, 300 m and 2 000 m at maximal effort for determination of Vcri that averaged 1.167 +/- 0.045 m . sec (-1). Since Vcri was equivalent to 90.5 % of the mean swimming velocity over the distance of 300 m at maximal effort, the swimming velocity obtained by multiplying the swimming velocity for the distance of 300 m of each subject by 90.5 % was taken to be 100 % of the predicted critical swimming velocity (Vcri-pred). Then, in an MLSS test, the subjects were instructed to swim breaststroke 2 000 m (5 x 400 m) at three constant velocities (98 %, 100 %, and 102 % of Vcri-pred), interrupted by four short rest periods from 30 to 45 seconds for blood sampling and heart rate measurement. As a result, the blood lactate concentration at 100 % Vcri-pred showed a higher steady state than the slow velocity, but at high velocity did not show the steady state. In conclusion, we can accurately estimate the Vcri for breaststroke by a one-time 300-m maximal effort swimming test.

  15. 3-D Velocity Estimation for Two Planes in vivo

    DEFF Research Database (Denmark)

    Holbek, Simon; Pihl, Michael Johannes; Ewertsen, Caroline;

    2014-01-01

    3-D velocity vectors can provide additional flow information applicable for diagnosing cardiovascular diseases e.g. by estimating the out-of-plane velocity component. A 3-D version of the Transverse Oscillation (TO) method has previously been used to obtain this information in a carotid flow phan...

  16. Quantitative assessment of regional myocardial function after percutaneous coronary intervention by velocity vector imaging in patients with acute myocardial infarction%速度向量成像评估急性心肌梗死患者经皮冠状动脉介入治疗效果

    Institute of Scientific and Technical Information of China (English)

    费杨华; 施仲伟; 许燕; 张凤如; 胡厚达; 曹敏

    2008-01-01

    目的 应用速度向量成像(VVI)技术分析急性心肌梗死患者冠状动脉介入治疗后左室壁运动的改变,评估治疗效果.方法 急性心肌梗死患者20例,在介入治疗术前3 d、术后1周内及术后3个月随访时分别行超声心动图检查,采用VVI技术测量心肌形变及时相指标.结果 与术前相比,梗死相关节段的应变、应变率、节段射血分数、收缩后应变指数等指标在介入治疗术后1周内已有改善,术后3个月随访时改善更加明显.结论 VVI技术可以作为评价血管再通治疗后局部心肌功能是否恢复以及恢复程度的一种无创性新方法.%Objective To evaluate left ventricular wall motion changes after successful pereutaneous coronary artery intervention (PCI) in patients with acute myocardial infarction (MI) by velocity vector imaging (VVI). Methods Twenty patients with acute MI, 16 anterior MI and 4 inferior MI,were studied by VVI within 3 days before PCI, 1 week and 3 months after PCI. The VVI parameters included peak systolic myocardial velocity (Vsys), peak systolic strain (εsys), maximal strain (εmax), peak systolic strain rate ( SRsys), isovolumic relaxation strain rate(SRivr),segmental ejection fraction (sEF), time to peak of velocity (TPKvel),and time to peak of strain (TPKε). Results Compared with that before PCI,εsys, SRsys, sEF, PSI, SRivr/SRsys, and TPKε were improved one week after PCI,and were further significantly improved at 3 months follow-up. Conclusions The VVI parameters can be used to evaluate the effectiveness of PCI shortly after the procedure and during long-term follow-up.

  17. 应变及应变率的速度向量成像定量分析诊断猪心肌挫伤%Diagnosis of Early Myocardial Contusion in Pigs by Velocity Vector Imaging and Quantitative Analysis of Strain and Strain Rate

    Institute of Scientific and Technical Information of China (English)

    王小燕; 王莎莎; 李叶阔; 朱贤胜; 程琦; 罗国新

    2010-01-01

    目的 探讨应变(strain,ε)、应变率(strain rate,SR)的速度向量成像(velocity vector imaging,VVI)定量分析对猪心肌挫伤(myocardial contusion,MC)的早期诊断价值.方法 建立8只猪MC模型.分别于撞击前及撞击后0.5、2、4、8 h,采集左室二尖瓣、乳头肌、心尖水平短轴切面VVI动态图像,利用VVI脱机分析软件获得左室短轴各节段径向峰值ε、SR.结果 撞击后MC节段左室径向峰值ε及SR测值低于撞击前(P<0.05),损伤节段的径向峰值ε及SR测值低于非损伤节段(P<0.05).结论 VVI技术能够定量评价MC后室壁运动异常,为MC早期诊断提供了新方法.

  18. Experimental investigation of transverse velocity estimation using cross-correlation

    DEFF Research Database (Denmark)

    Bjerngaard, Rasmus; Jensen, Jørgen Arendt

    2001-01-01

    A technique for estimating the full flow velocity vector has previously been presented by our group. Unlike conventional estimators, that only detect the axial component of the flow, this new method is capable of estimating the transverse velocity component. The method uses focusing along the flow....... A mean parabolic velocity profile was obtained for purely transverse flow with a mean bias to the true profile of -2.5% relative to the peak velocity and a standard deviation of 13.3% relative to the peak velocity. Twenty pulse-echo lines were used for each estimate and 18 profiles were obtained...

  19. 高血压患者脉搏波传导速度与血压负荷关系的研究%Study on the relationship between brachial-ankle pulse wave velocity and blood pressure load in hypertensive patients

    Institute of Scientific and Technical Information of China (English)

    王宁; 余振球

    2012-01-01

    Objective;To explore the relationship between brachial-ankle pulse wave velocity and blood pressure load in hypertensive patients. Methods: 348 patients were enrolled in this study. Ambulatory blood pressure (ABP) and brachial-ankle pulse wave velocity (BAPWV) were measured. According to the value of BAPWV, all patients were divided into two groups; BAPWV normal group (bapwv < 1400 cm/s, n = 121) and BAPWV elevated group (bapwv ^ 1400 cm/s, n = 227). The patients' age, gender ratio, fasting blood glucose (FBG), triglyceride (TG), cholesterol (CHO), low density lipoprotein cholesterol (LDL), high density lipc-protein cholesterol (HDL) , creatinine ( Cr) , uric acid ( UA) , blood pressure level and blood pressure load were measured. Results: Univariate analysies revealed that age, TG, CHO, LDL, blood pressure and blood pressure load in BAPWV elevated group were significantly higher than those in BAPWV normal group ( P < 0.05). Logistic multivariate regression analysis indicated that age, nighttime systolic blood pressure load and nighttime diastolic blood pressure load were independent influencing factors of BAPWV. Conclusion: nighttime systolic blood pressure load and nighttime diastolic blood pressure load of hypertensive patients were independent influencing factors of BAPWV.%[目的]:探讨高血压患者臂踝脉搏波传导速度(BAPOWV)与血压负荷的关系.[方法]:入选原发性高血压患者348例,进行24h动态血压监测和BAPWV测定,根据BAPWV的值,将其分为2组:BAPWV正常组(BAPWV< 1400cm/s)121例,BAPWV升高组(BAPWV≥1400 cm/s)227例.比较2组患者年龄、性别构成比、血糖、血脂、血肌酐、血尿酸、血压及血压负荷.结果:单因素分析显示,BAPWV升高组患者的年龄、三酰甘油、胆固醇、低密度脂蛋白、血压及血压负荷均显著高于BAPWV正常组(P<0.05).Logistic回归分析表明年龄、夜间收缩压负荷及夜间舒张压负荷是影响BAPWV的独立因素(P<0.05).结论:高

  20. Teaching Universal Gravitation with Vector Games

    Science.gov (United States)

    Lowry, Matthew

    2008-01-01

    Like many high school and college physics teachers, I have found playing vector games to be a useful way of illustrating the concepts of inertia, velocity, and acceleration. Like many, I have also had difficulty in trying to get students to understand Newton's law of universal gravitation, specifically the inverse-square law and its application to…

  1. Velocity-aligned Doppler spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.; Koplitz, B.; Wittig, C.

    1989-03-01

    The technique of velocity-aligned Doppler spectrosocopy (VADS) is presented and discussed. For photolysis/probe experiments with pulsed initiation, VADS can yield Doppler profiles for nascent photofragments that allow detailed center-of-mass (c.m.) kinetic energy distributions to be extracted. When compared with traditional forms of Doppler spectroscopy, the improvement in kinetic energy resolution is dramatic. Changes in the measured profiles are a consequence of spatial discrimination (i.e., focused and overlapping photolysis and probe beams) and delayed observation. These factors result in the selective detection of species whose velocities are aligned with the wave vector of the probe radiation k/sub pr/, thus revealing the speed distribution along k/sub pr/ rather than the distribution of nascent velocity components projected upon this direction. Mathematical details of the procedure used to model VADS are given, and experimental illustrations for HI, H/sub 2/S, and NH/sub 3/ photodissociation are presented. In these examples, pulsed photodissociation produces H atoms that are detected by sequential two-photon, two-frequency ionization via Lyman-..cap alpha.. with a pulsed laser (121.6+364.7 nm), and measuring the Lyman-..cap alpha.. Doppler profile as a function of probe delay reveals both internal and c.m. kinetic energy distributions for the photofragments. Strengths and weaknesses of VADS as a tool for investigating photofragmentation phenomena are also discussed.

  2. Effects of desflurane,isoflurane,and sevoflurane on cerebral blood flow velocity%地氟醚、异氟醚和七氟醚对脑血流速率的影响

    Institute of Scientific and Technical Information of China (English)

    陈绍辉; 黄宇光; 黄一宁; 徐仲煌; 张秀华; 杨克勤

    2001-01-01

    Objective The purpose of the study was to evaluate the effects ofthree inhalational anesthetics,desflurane,isoflurane and sevoflurane,on the mean velocity of cerebral blood flow of middle cerebral artery by transcranial Doppler ultrasonography (TCD).Methods Forty-two patients,aged from 18 to 60 years old with ASA physical status Ⅰ or Ⅱ,undergoing elective non-neurosurgical operations under general anesthesia were recruited.They were randomly assigned to three groups to receive desflurane-O2,isoflurane-O2,or sevoflurane-O2 anesthesia,respectively.The pressure of end-tidal carbon dioxide was kept to 40±1mmHg by mechanical ventilation.TCD datum,mean velocity (Vm)of middle cerebral artery was recorded when endtidal concentrations of the selected anesthetics maintained at following occasions:equilibration at 1.0MAC for 15min;immediately after a rapid increase (within 2min)from 1.0MAC to 1.5MAC;equilibration at 1.5MAC for 15min;maintained at 1.5MAC and the mean arterial blood pressure (MAP)was adjusted close to that of 1.0MAC by phenylephrine infusion,simultaneously,together with MAP and heart rate (HR).Results Compared to the values under 1.0MAC anesthesia,the results under different conditions were represented as follows:(1)Vm increased significantly when maintained at 1.5MAC and MAP was similar to that of 1.0MAC in desflurane and isoflurane group (from 56cm/s to 61cm/s and from 47cm/s to 52cm/s,respectively,P<0.01),but without any significant change in sevoflurane group (from 60cm/s to 60cm/s,P>0.05).(2)After a rapid increase (within 2min)from 1.0MAC to 1.5MAC,desflurane caused a significant increase in MAP,HR and Vm(from 56cm/s to 61cm/s,P<0.01);isoflurane induced a significant decrease in MAP,but little change in Vm(from 47cm/s to 49cm/s, P>0.05),and sevoflurane resulted in remarkable decrease in Vm(from 60cm/s to

  3. The Representation of a Broadband Vector Field

    Institute of Scientific and Technical Information of China (English)

    Qunyan Ren; Jean Pierre Hermand; Shengchun Piao

    2011-01-01

    Compared to a scalar pressure sensor,a vector sensor can provide a higher signal-to-noise ratio (SNR)signal and more detailed information on the sound field.Study on vector sensors and their applications have become a hot topic.Research on the representation of a vector field is highly relevant for extending the scope of vector sensor technology.This paper discusses the range-frequency distribution of the vector field due to a broadband acoustic source moving in a shallow-water waveguide as the self noise of a surface ship,and the vector extension of the waveguide impulse response measured over a limited frequency range using an active source of known waveform.From theory analysis and numerical simulation,the range-frequency representation of a vector field exhibits an interference structure qualitatively similar to that of the corresponding pressure field but,being quantitatively different,provides additional information on the waveguide,especially through the vertical component.For the range-frequency representation,physical quantities that can better exhibit the interference characteristics of the waveguide are the products of pressure and particle velocity and of the pressure and pressure gradient.An image processing method to effectively detect and isolate the individual striations from an interference structure was reviewed briefly.The representation of the vector impulse response was discussed according to two different measurement systems,also known as particle velocity and pressure gradient.The vector impulse response representation can not only provide additional information from pressure only but even more than that of the range-frequency representation.

  4. Blood sugar test - blood

    Science.gov (United States)

    ... blood glucose level ( hypoglycemia ) may be due to: Hypopituitarism (a pituitary gland disorder) Underactive thyroid gland or ... tonic-clonic seizure Glucagon blood test Glucagonoma Hyperthyroidism Hypopituitarism Hypothyroidism Insulinoma Low blood sugar Multiple endocrine neoplasia ( ...

  5. How to measure propagation velocity in cardiac tissue: a simulation study

    Directory of Open Access Journals (Sweden)

    Andre C. Linnenbank

    2014-07-01

    Full Text Available To estimate conduction velocities from activation times in myocardial tissue, the average vector method computes all the local activation directions and velocities from local activation times and estimates the fastest and slowest propagation speed from these local values. The single vector method uses areas of apparent uniform elliptical spread of activation and chooses a single vector for the estimated longitudinal velocity and one for the transversal. A simulation study was performed to estimate the influence of grid size, anisotropy, and vector angle bin size. The results indicate that the average vector method can best be used if the grid- or bin-size is large, although systematic errors occur. The single vector method performs better, but requires human intervention for the definition of fiber direction. The average vector method can be automated.

  6. 速度向量成像技术分析妊娠高血压综合征孕妇胎儿左室心肌力学%Evaluation of fetal myocardial mechanics of left ventricular in pregnancy-induced hypertension syndrome using velocity vector imaging

    Institute of Scientific and Technical Information of China (English)

    刘芳; 陶国伟; 姜丽丽; 刘韶平; 石琳琳; 丁婷婷; 高圣洁; 马喆

    2014-01-01

    目的:应用速度向量成像(VVI)技术定量分析妊娠高血压综合征(妊高征)孕妇胎儿左室心肌力学,寻找评价胎儿心肌力学最有价值的指标。方法妊高征组孕妇36例,对照组孕妇54例。应用VVI技术评价胎儿左室心肌收缩期和舒张期6个节段及整体峰值速度、应变、应变率,评价妊高征孕妇胎儿心肌力学的特点,并与对照组参数进行比较。结果①妊高征组胎儿左室收缩期和舒张期节段峰值速度、应变和应变率小于对照组,部分节段差异有统计学意义(P<0.05);②妊高征组胎儿左室收缩期和舒张期整体峰值速度、应变和应变率均小于正常对照组(P<0.05)。结论 VVI技术能敏感地反映妊高征孕妇胎儿心肌力学的变化。与节段应变和应变率比较,整体峰值应变和应变率更加敏感,将有望成为评价胎儿心肌力学最有价值的指标之一。%Objective To explore the most valuable parameters for fetal myocardial mechanics by evaluating fetal left ventricular myocardial mechanics in women with pregnancy-induced hypertension syndrome using velocity vector ima-ging (VVI).Methods The study involved two groups of pregnant women:the hypertensive group (women with pregnancy-induced hypertension,n=36)and control group (healthy subjects,n=54).The ventricular systolic and di-astolic segmental and global peak velocity,strain,and strain rate were evaluated with VVI and compared between the two groups.Results Systolic and diastolic segmental peak velocity,strain and strain rate of the hypertensive group were lower than those of the control group.There were statistical differences in some of the segments (P<0.05).②Systolic and diastolic global peak velocity,strain and strain rate of the hypertensive group were lower than those of the control group (P<0.05).Conclusion VVI can sensitively reflect the fetal myocardial mechanics in women with

  7. 速度向量成像技术评价正常人左心室节段心肌收缩功能的初步研究%The preliminary research on evaluate the left ventricular segmental myocardial systolic function in normal subjects by velocity vector imaging

    Institute of Scientific and Technical Information of China (English)

    孙丽; 薛红元; 叶玉泉; 高丽; 李丽; 焦荣红

    2012-01-01

    Objective To compare left ventricular longitudinal and radial direction movement characteristic, which are of the same segments of normal myocardium under the resting state by velocity vector imaging ( WI ). Then evaluate clinical practice value of WI on normal subjects segmental systolic function. Methods Thirty healthy volunteers were enrolled, and then selected clearly apical four chamber view, apical two chamber view, apical left ventricular long axis view, axis view at papillary level, muscle level and nearly apical level. Quantitative analysis velocity ( Vs ), strain ( S ), strain rate ( SR ) about radial motion of left ventricle anterior septum, anterior, lateral wall, inferior, posterior wall and posterior septal; and longitudinal motion of normal segments from basal segment, middle segment and apical segment. Results From basal segment to apex, the velocity gradient descent as basal segment > medial segment > apical segment P 0. 05 ). Radial velocity, strain rate and strain among the different walls of the left ventricle are the same( P >0. 05 ). Conclusion This research indicates that WI can be used as quantitatively assess left ventricular segmental systolic function. To provide a new method for clinical evaluation cardiac motion and function.%目的 应用速度向量成像技术(VVI)比较静息状态下左心室相同节段的正常心肌纵向和径向的运动特点,评价VVI技术对正常人左心室节段心肌收缩功能的临床应用价值.方法 选取健康志愿者30例,采用西门子公司Sequoia 512超声诊断仪,在VVI模式下选取心尖四腔、心尖二腔、心尖左室长轴;二尖瓣水平、乳头肌水平及近心尖水平左室短轴切面,定量分析左室前间隔、前壁、侧壁、下壁、后壁及后间隔的径向运动,以及纵向的基底段、中间段及心尖段等3个分段中正常心肌节段的心肌运动速度(Vs)、应变(S)、应变率(SR).结果 正常人左心室各室壁基底段、中间段和心

  8. Transverse Spectral Velocity Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    A transverse oscillation (TO)-based method for calculating the velocity spectrum for fully transverse flow is described. Current methods yield the mean velocity at one position, whereas the new method reveals the transverse velocity spectrum as a function of time at one spatial location. A convex...

  9. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Bechsgaard, Thor

    2016-01-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view...... (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter....... In-vivo acquisitions show complex flow patterns in the heart. In the aortic valve view, blood is seen exiting the left ventricle cavity through the aortic valve into the aorta during the systolic phase of the cardiac cycle. In the left ventricle view, blood flow is seen entering the left ventricle...

  10. The Role of the Harmonic Vector Average in Motion Integration

    Directory of Open Access Journals (Sweden)

    Alan eJohnston

    2013-10-01

    Full Text Available The local speeds of object contours vary systematically with the cosine of the angle between the normal component of the local velocity and the global object motion direction. An array of Gabor elements whose speed changes with local spatial orientation in accordance with this pattern can appear to move as a single surface. The apparent direction of motion of plaids and Gabor arrays has variously been proposed to result from feature tracking, vector addition and vector averaging in addition to the geometrically correct global velocity as indicated by the intersection of constraints (IOC solution. Here a new combination rule, the harmonic vector average (HVA, is introduced, as well as a new algorithm for computing the IOC solution. The vector sum can be discounted as an integration strategy as it increases with the number of elements. The vector average over local vectors that vary in direction always provides an underestimate of the true global speed. The harmonic vector average however provides the correct global speed and direction for an unbiased sample of local velocities with respect to the global motion direction, as is the case for a simple closed contour. The HVA over biased samples provides an aggregate velocity estimate that can still be combined through an IOC computation to give an accurate estimate of the global velocity, which is not true of the vector average. Psychophysical results for type II Gabor arrays show perceived direction and speed falls close to the intersection of constraints direction for Gabor arrays having a wide range of orientations but the IOC prediction fails as the mean orientation shifts away from the global motion direction and the orientation range narrows. In this case perceived velocity generally defaults to the harmonic vector average.

  11. PIV Investigations of the Flow Field in the Volute of a Rotary Blood Pump

    Science.gov (United States)

    Sankovic, John M.; Kadambi, Jaikrishnan R.; Smith, William A.; Wernet, Mark P.

    2004-01-01

    A full-size acrylic model of a rotary blood pump was developed in order to utilize Particle Image Velocimetry (PIV) to make measurements of the fluid velocities and turbulent stresses throughout the device. The development of an understanding of the hemodynamics within the blood pump is critical to the development and validation of computational models. A blood analog solution, consisting of sodium iodide solution and glycerin, was developed to match physiological kinematic viscosity. The refractive indices of the fluid, the pump casing, and the impeller were matched to facilitate the use of PIV to make velocity measurements. Velocity measurements made in the volute exit/diffuser region are presented for pumps speeds of 3000-3850 rpm. At each speed data were obtained at a physiological pressure of 12 kPa and at a maximum flow condition. Four hundred data pairs were used for each resultant mean velocity vector value, representing greater than an order of magnitude more data pairs than reported previously in the literature on similar devices and resulting in velocity uncertainty levels of approximately 22.9%.

  12. Detection probabilities for time-domain velocity estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1991-01-01

    Estimation of blood velocities by time-domain cross-correlation of successive high frequency sampled ultrasound signals is investigated. It is shown that any velocity can result from the estimator regardless of the true velocity due to the nonlinear technique employed. Using a simple simulation...... as a filter with a transfer function depending on the actual velocity. This influences the detection probability, which gets lower at certain velocities. An index directly reflecting the probability of detection can easily be calculated from the cross-correlation estimated. This makes it possible to assess...... the reliability of the velocity estimate in real time...

  13. 速度向量成像对不伴心肌梗死的冠心病患者左室收缩应变的研究%Assessments of Left Ventricular Peak Systolic Strain with Velocity Vector Imaging in the Patients with Coronary Disease without Myocardial Infarction

    Institute of Scientific and Technical Information of China (English)

    李华; 陈斌; 胡元平; 田新桥; 徐峰

    2011-01-01

    目的 探讨速度向量成像技术(velocity vector imaging,VVI)对不伴心肌梗死的冠心病患者的诊断价值.方法对72例冠心病患者进行超声心动图检查,并追踪造影结果,应用VVI软件测量心肌纵向、径向、圆周左室峰值收缩期应变,根据冠脉造影结果分为3组,A组:冠造阴性及狭窄程度<50%,B组:50%≤狭窄程度<75%,C组:狭窄程度≥75%,比较组间差异.结果 C组与A、B组之间纵向峰值收缩应变差异有统计学意义(P<0.05),截断值-18.28%,诊断狭窄程度≥75%的特异度为80%,敏感度为76%;C组与A、B组之间径向峰值收缩应变差异有统计学意义(P<0.05),截断值25.88%,诊断狭窄程度≥75%的特异度为71%,敏感度为70%;而C组与A、B组之间圆周峰值收缩应变差异无统计学意义(P >0.05);A组与B组之间纵向、径向及圆周峰值收缩应变差异均无统计学意义(均P >0.05).结论 VVI能帮助检测出不伴心肌梗死而有重度冠脉狭窄患者的左室心肌收缩功能异常.%Objective To evaluate the diagnostic values by using velocity vector imaging in patients with coronary disease without myocardial infarction. Methods On conventional two- dimensional echocardiography, 72 patients were examed and underwent coronary angiography within one week. The myocardial longitudinal, radial and circumferential strain were measured. The patients were classified into three groups according to the result of coronary angiography (A:0.05). There were no significant differences in longitudinal, radial and circumferential strain between the intermediate group and the control group (P >0.05). Conclusion WI can help to identify left ventricular myocardial systolic function abnormalities in patients with severe coronary stenosis but without myocardial infarction.

  14. Velocity estimation using synthetic aperture imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    In a previous paper we have demonstrated that the velocity can be estimated for a plug flow using recursive ultrasound imaging [1]. The approach involved the estimation of the velocity at every emission and using the estimates for motion compensation. An error in the estimates, however, would lead...... to an error in the compensation further increasing the error in the estimates. In this paper the approach is further developed such that no motion compensation is necessary. In recursive ultrasound imaging a new high resolution image is created after every emission. The velocity was estimated by cross...... and significantly improves the velocity estimates. The approach is verified using simulations with the program Field II and measurements on a blood-mimicking phantom. The estimates from the simulations have a bias of -3.5% and a mean standard deviation less than 2.0% for a parabolic velocity profile. The estimates...

  15. Concise vector analysis

    CERN Document Server

    Eliezer, C J; Maxwell, E A; Sneddon, I N

    1963-01-01

    Concise Vector Analysis is a five-chapter introductory account of the methods and techniques of vector analysis. These methods are indispensable tools in mathematics, physics, and engineering. The book is based on lectures given by the author in the University of Ceylon.The first two chapters deal with vector algebra. These chapters particularly present the addition, representation, and resolution of vectors. The next two chapters examine the various aspects and specificities of vector calculus. The last chapter looks into some standard applications of vector algebra and calculus.This book wil

  16. Light axial vector mesons

    CERN Document Server

    Chen, Kan; Liu, Xiang; Matsuki, Takayuki

    2015-01-01

    Inspired by the abundant experimental observation of axial vector states, we study whether the observed axial vector states can be categorized into the conventional axial vector meson family. In this paper we carry out analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial vector mesons, which are valuable to further experimental exploration of the observed and predicted axial vector mesons.

  17. Multiple incoherent sound source localization using a single vector sensor

    NARCIS (Netherlands)

    Basten, T.G.H.; Bree, H.E. de; Druyvesteyn, W.F.; Wind, J.W.

    2009-01-01

    With the Microflown acoustic particle velocity sensor, broadband acoustic vector sensors in air have become available. An assembled probe version is based upon three orthogonally placed acoustic particle velocity sensors and a single sound pressure sensor. This probe has also become available as a m

  18. Vector Along-Track Interferometry for Ocean Current mapping

    Science.gov (United States)

    Rodriguez, Ernesto; Imel, David; Madsen, Soren

    1996-01-01

    We examine the feasibility of measuring Along-Track Interferometric (ATI) vector ocean velocities using the azimuth beamwidth of the SAR antenna to obtain angular diversity, at the expense of spatial resolution. A simple model of the measurement is introduced for point targets and moving ocean surfaces to help interpret the velocity measurements.

  19. Inertial Measurements Based Velocity-free Attitude Stabilization

    CERN Document Server

    Tayebi, A; Benallegue, A

    2012-01-01

    The existing attitude controllers (without angular velocity measurements) involve explicitly the orientation (\\textit{e.g.,} the unit-quaternion) in the feedback. Unfortunately, there does not exist any sensor that directly measures the orientation of a rigid body, and hence, the attitude must be reconstructed using a set of inertial vector measurements as well as the angular velocity (which is assumed to be unavailable in velocity-free control schemes). To overcome this \\textit{circular reasoning}-like problem, we propose a velocity-free attitude stabilization control scheme relying solely on inertial vector measurements. The originality of this control strategy stems from the fact that the reconstruction of the attitude as well as the angular velocity measurements are not required at all. Moreover, as a byproduct of our design approach, the proposed controller does not lead to the unwinding phenomenon encountered in unit-quaternion based attitude controllers.

  20. Amplitude, phase, location and orientation calibration of an acoustic vector sensor array, part I: Theory

    NARCIS (Netherlands)

    Xu, B.; Wind, J.; Bree, H.E. de; Basten, T.G.H.; Druyvesteyn, E.

    2010-01-01

    An acoustic vector sensor array consists of multiple sound pressure microphones and particle velocity sensors. A pressure microphone usually has an omni-directional response, yet a particle velocity sensor is directional. Currently, acoustic vector sensor arrays are under investigation for far field

  1. VectorBase

    Data.gov (United States)

    U.S. Department of Health & Human Services — VectorBase is a Bioinformatics Resource Center for invertebrate vectors. It is one of four Bioinformatics Resource Centers funded by NIAID to provide web-based...

  2. 速度向量成像评价1型糖尿病兔模型心功能演变过程%Velocity Vector Imaging in Assessing the Cardiac Functional Evolution in Type 1 Diabetes Mellitus Rabbit Model

    Institute of Scientific and Technical Information of China (English)

    蒋涛; 袁亮辉; 周启昌

    2013-01-01

    目的 运用速度向量成像技术(VVI)对糖尿病兔心脏运动功能变化进行监测,并通过不同时期的心肌病理切片对照,探讨糖尿病兔心脏运动功能变化的特点.方法 采用耳缘静脉注射链脲佐菌素(65mg/kg)诱导1型糖尿病兔模型;运用VVI获得糖尿病兔左心室心肌各节段最大收缩期运动速度(Vs)、最大舒张期运动速度(Vd)、最大收缩期应变(Ss)、最大收缩期应变率(SRs)、最大舒张期应变率(SRd)等参数,进行评估其心脏运动功能变化状况;应用10%甲醛固定及石蜡包埋技术制备心肌病理切片.结果 成模2周后即可发现糖尿病兔心脏短轴Ss、SRs、SRd下降,并于成模4~12周后呈逐步减低趋势,与同期心肌病理改变情况一致.结论 VVI可早期发现糖尿病性心肌病心脏运动功能的改变.%Objective Using the Velocity Vector Imaging (VVI) to monitor the cardiac functional evolution in diabetes mellitus rabbits.Through contrasting to the different period of myocardial pathological changes,discuss the cardiac function characteristics of diabetic rabbit.Methods Type 1 diabetic rabbits were induced by injecting treptozotocin (65 mg/kg) in ear vein; using the VVI to obtain parameters such as the maximum systolic velocity (Vs),the maximum diastolic velocity (Vd),the maximum systolic strain (Ss),the maximum systolic strain rate (SRs),the maximal diastolic strain rate (SRd) of left ventricular myocardial segments to monitor the cardiac motor functional changes of diabetes mellitus rabbits and contrast to the different period of myocardial pathological changes; applicating 10% formaldehyde-fixed and paraffin-embedded technology to prepare myocardial pathological sections.Results The radial Ss,SRs,SRd were reduced right after 2 weeks and aprogressive reducing in 4~12 weeks after the model establised successfully (P < 0.05).The changes were according with the same period myocardial pathological.Conclusions VVI can be

  3. Assessment of left ventricular contraction asynchrony in patients with acute myocardial infarction using velocity vector imaging%速度向量成像技术评价急性心肌梗死患者左心室不同步运动的临床研究

    Institute of Scientific and Technical Information of China (English)

    谢芳; 黄宇玲; 李海朋

    2011-01-01

    Objective To assess the left ventricular contraction asynchrony in patients with acute myocardial infarction(AMI) by velocity vector imaging(VVI).Methods Sixty AMI patients and 40 healthy volunteers were included.Using VVI,the time to peak longitudinal systolic velocity (TL-V) was measured in the left ventricular long axis views,the time to peak radial systolic velocity (TR-V) was measured in parasternal short axis views.The deviation of the earliest and the latest TL-V and TR-V (Ts max-min) was measured,and the standard deviation of TL-V and TR-V (TS-SD) was also measured.Results ①TL-V ,TR-V of the infarcted and non-infarcted segments in patients with acute myocardial infarction were longer than those of the normal segments (P <0.05).②The longitudinal Tsmax-min,Ts-SD and the radial Tsmax-min,Ts-SD in infarcted patients were increased compared with the healthy volunteers (P <0.001).③Ts of the infarcted segments was increased in turn from the class Ⅰ to class Ⅳ of the cardiac function (P <0.001).Conclusions VVI could be used to assess the left ventricular contraction asynchrony in patients with AMI.VVI is a new useful method to determine the infarcted segments.%目的 应用速度向量成像(VVI)技术评价急性心肌梗死(AMI)患者心脏不同步运动.方法 选择AMI患者60例和健康志愿者40例,采用VVI技术测量并比较两组间左室局部心肌纵向收缩速度达峰时间(TL-V)、左室局部心肌径向收缩速度达峰时间(T R-V)、左室最早与最迟速度达峰时间的差值(Ts max-min)、左室16节段速度达峰时间标准差(Ts-SD)的差异.结果 ①AMI组梗死节段与非梗死节段心肌TL-V、TR-V分别大于对照组正常节段(P<0.05);②AMI组纵向及径向Ts max-min、Ts-SD均大于对照组(P<0.001);③AMI组梗死节段心肌Ts从心功能Ⅰ级至Ⅳ级依次延长(P<0.001).结论 VVI技术为评价AMI患者心肌不同步运动及判断梗死节段提供了一种新的方法.

  4. On Double Vector Bundles

    Institute of Scientific and Technical Information of China (English)

    Zhuo CHEN; Zhang Ju LIU; Yun He SHENG

    2014-01-01

    In this paper, we construct a category of short exact sequences of vector bundles and prove that it is equivalent to the category of double vector bundles. Moreover, operations on double vector bundles can be transferred to operations on the corresponding short exact sequences. In particular, we study the duality theory of double vector bundles in term of the corresponding short exact sequences. Examples including the jet bundle and the Atiyah algebroid are discussed.

  5. On Double Vector Bundles

    OpenAIRE

    Chen, Zhuo; Liu, Zhangju; Sheng, Yunhe

    2011-01-01

    In this paper, we construct a category of short exact sequences of vector bundles and prove that it is equivalent to the category of double vector bundles. Moreover, operations on double vector bundles can be transferred to operations on the corresponding short exact sequences. In particular, we study the duality theory of double vector bundles in term of the corresponding short exact sequences. Examples including the jet bundle and the Atiyah algebroid are discussed.

  6. Custodial vector model

    DEFF Research Database (Denmark)

    Becciolini, Diego; Franzosi, Diogo Buarque; Foadi, Roshan;

    2015-01-01

    We analyze the Large Hadron Collider (LHC) phenomenology of heavy vector resonances with a $SU(2)_L\\times SU(2)_R$ spectral global symmetry. This symmetry partially protects the electroweak S-parameter from large contributions of the vector resonances. The resulting custodial vector model spectrum...

  7. Relationship between Blood Pressure Variability and Brachial-ankle Pulse Wave Velocity in Hypertensive Patients%高血压患者血压变异性与肱踝脉搏波传导速度的关系研究

    Institute of Scientific and Technical Information of China (English)

    王宁; 余振球

    2012-01-01

    目的 探讨高血压患者血压变异性与肱踝脉搏波传导速度(brachial-ankle pulse wave velocity,baPWV)的关系.方法 选择原发性高血压患者313例,根据baPWV值,将其分为两组:baPWV正常组(baPWV<1 400 cm/s)87例,baPWV升高组(baPWV≥1 400 cm/s)226例.比较两组患者年龄、性别构成比、血糖、血脂、血肌酐、血尿酸、血压及血压变异性.结果 单因素分析显示,baPWV升高组患者的年龄、胆固醇、低密度脂蛋白、高密度脂蛋白、24 h平均收缩压、24 h收缩压变异性及24 h舒张压变异性均高于baPWV正常组(P<0.05),代入Logistic回归分析显示年龄、胆固醇、高密度脂蛋白、24 h平均收缩压、24 h收缩压变异性及24 h舒张压变异性与baPWV呈相关性(P<0.05).结论 高血压患者24 h收缩压变异性和舒张压变异性是影响baPWV的独立因素.%Objective To explore the relationship between blood pressure variability and brachial - ankle pulse wave velocity ( baPWV ) in hypertensive patients. Methods Totally 313 patients with essential hypertension were enrolled in this study and divided into normal baPWV group ( baPWV < 1 400cm/s, n =87 ) and high baPWV group ( baPWV≥1 400cm/s, n= 226 ) based on their baPWV values. Age, gender ratio, fasting blood glucose ( FBG ), blood lipids including cholesterol ( CHO ), low - density lipoprotein cholesterol ( LDL ), and high - density lipoprotein cholesterol ( HDL ), serum creatinine ( Cr ), blood uric acid ( UA ), blood pressure, and blood pressure variability were measured. Results Univariate analysis revealed that age, CHO, LDL, HDL, 24 - hour systolic blood pressure, 24 - hour systolic blood pressure variability, and 24 -hour diastolic blood pressure variability were significantly higher in high baPWV group than in normal baPWV group ( P <0. 05 ). Multivariate Logistic regression analysis indicated that age, CHO, HDL, 24 -hour systolic blood pressure, 24 -hour systolic blood pressure variability

  8. Quantification of aortic regurgitation by magnetic resonance velocity mapping

    DEFF Research Database (Denmark)

    Søndergaard, Lise; Lindvig, K; Hildebrandt, P;

    1993-01-01

    The use of magnetic resonance (MR) velocity mapping in the quantification of aortic valvular blood flow was examined in 10 patients with angiographically verified aortic regurgitation. MR velocity mapping succeeded in identifying and quantifying the regurgitation in all patients, and the regurgit......The use of magnetic resonance (MR) velocity mapping in the quantification of aortic valvular blood flow was examined in 10 patients with angiographically verified aortic regurgitation. MR velocity mapping succeeded in identifying and quantifying the regurgitation in all patients......, and the regurgitant volume determined with MR velocity mapping agreed well with the grade obtained by aortic root angiography (p velocity mapping...... and calculated from MR imaging of the left ventricular end-diastolic and end-systolic volumes in eight patients (Y = 0.89 x X + 11, r = 0.97, p velocity mapping and simultaneous 125I...

  9. ON THE ISSUE OF VECTOR CONTROL OF THE ASYNCHRONOUS MOTORS

    Directory of Open Access Journals (Sweden)

    B. I. Firago

    2015-01-01

    Full Text Available The paper considers the issue of one of the widespread types of vector control realization for the asynchronous motors with a short-circuited rotor. Of all more than 20 vector control types known presently, the following are applied most frequently: direct vector control with velocity pickup (VP, direct vector control without VP, indirect vector control with VP and indirect vector control without VP. Despite the fact that the asynchronous-motor indirect vector control without VP is the easiest and most spread, the absence of VP does not allow controlling the motor electromagnetic torque at zero velocity. This is the reason why for electric motor drives of such requirements they utilize the vector control with a velocity transducer. The systems of widest dissemination became the direct and indirect vector control systems with X-axis alignment of the synchronously rotating x–y-coordinate frame along the rotor flux-linkage vector inasmuch as this provides the simplest correlations for controlling variables. Although these two types of vector control are well presented in literature, a number of issues concerning their realization and practical application require further elaboration. These include: the block schemes adequate representation as consisted with the modern realization of vector control and clarification of the analytical expressions for evaluating the regulator parameters.The authors present a technique for evaluating the dynamics of an asynchronous electric motor drive with direct vector control and x-axis alignment along the vector of rotor flux linkage. The article offers a generalized structure of this vector control type with detailed description of its principal blocks: controlling system, frequency converter, and the asynchronous motor.The paper presents a direct vector control simulating model developed in the MatLab environment on the grounds of this structure. The authors illustrate the described technique with the results

  10. Evaluation of radial systolic function of left ventricular with myocardial infarction by velocity vector imaging%速度向量成像技术评价心肌梗死节段室壁径向收缩能力的价值

    Institute of Scientific and Technical Information of China (English)

    杨娅; 谢谨捷; 李治安; 孟圆峰; 郝晓晔; 张京岚

    2010-01-01

    目的 探讨速度向量成像(VVI)技术评价心肌梗死节段径向收缩能力的价值.方法 将雄性Wister大鼠分为两组,一组结扎冠状动脉制成心肌梗死模型组(10只),另一组同样进行手术但不结扎冠状动脉作为对照组(14只).应用VVI技术对左室短轴乳头肌水平室壁径向应变及应变率进行分析.结果 心肌梗死组梗死节段(左室前壁及前间隔)径向应变及应变率较对照组相应节段明显减低,两组间差异具有统计学意义(P0.05).结论 VVI技术能够定量评价心肌梗死节段室壁的径向收缩能力.%Objective To explore the value of velocity vector imaging(VVI)in evaluating radial systolic function of left ventricular with myocardial infarction(MI).Methods Twenty-four male Wister rats were divided into MI group(n=10)and control group(n=14).Left main coronary artery of MI group were ligated,and the similar operation were performed in control group without coronary artery ligation.VVI was used to analyse the radial strain and strain rate of regional left ventricule in rata.Results Compared with control group,the radial strain and strain rate of infarcted segments(anterior wall and anterior septal)were decreased significantly(P0.05)was found when compared radial strain and strain rate in different left ventricle segments in control group.Conclusions VVI can be used as a quantitive tool in evaluating the radial systolic function of left ventricular with MI.

  11. Differences in myocardial deformation between donor and recipient in twin-twin transfusion syndrome using vector velocity imaging%速度向量成像评价双胎输血综合征胎儿心肌力学的探讨

    Institute of Scientific and Technical Information of China (English)

    曾施; 周启昌; 田志云; Jack Rychik

    2011-01-01

    Objective To investigate the differences in myocardial deformation between donor and recipient in twin-twin transfusion syndrome(TTTS) using vector velocity imaging( VVI). Methods Digital dynamic two-dimensional four chamber views were interrogated off-line using VVI software. Global longitudinal strain(S) , systolic strain rate(SRs) and diastolic strain rate(SRd) were measured in the left ventricles(LV) and right ventricles (RV) of 30 fetal pairs with TTTS and compared to 30 gestational age-matched normal controls. Results Donor LV-SRs was higher, while donor RV-SRd was significantly lower than controls. Recipient S, SRs and SRd were significantly lower for both LV and RV in comparison to controls. Conclusions In TTTS,donor LV systolic function is hyperdynamic while the RV diastolic function is low. Recipient RV and LV are both globally depressed with systolic and diastolic dysfunction.%目的 应用速度向量成像技术分析双胎输血综合征供血胎儿和受血胎儿的心功能改变,探讨两者之间的心肌力学差异.方法 动态采集30例双胎输血综合征胎儿和30例孕龄匹配的正常对照胎JL--维标准四腔心数字化图像,用心肌速度向量软件分析左室(LV)和右室(RV)长轴方向心肌应变(S)、收缩期应变率(SRs)和舒张期应变率(SRd).结果 与正常对照组相比,供血胎儿左室SRs升高,右室SRd明显减低.而受血胎儿左室和右室的S、SRs和SRd均明显减低.结论 双胎输血综合征中供血胎儿和受血胎儿的心功能均有所改变,供血胎儿左室收缩功能代偿性增强而右室舒张功能减弱,受血胎儿则表现为心肌功能广泛减退.

  12. Evaluation of early neonatal left ventricular short-axis motion by velocity vector imaging%速度向量成像技术对早期新生儿左室短轴运动变化的临床研究

    Institute of Scientific and Technical Information of China (English)

    郑毅; 周青; 陈欣林; 何莎; 黄君红

    2012-01-01

    Objective To assess the application value of velocity vector imaging (VVI)in evaluating left ventricular short-axis motion in early neonate. Methods Thirty-two full-term newborns were divided into four groups according to age in this study(24 h, 48 h, 72 h and 96 h). The short-axis contraction motion of left ventricle was dynamically monitored by VVI, the systolic peak velocity(SRVmax), systolic peak radial strain(SRSmax) and the systolic peak circumferential strain(SCSmax) of 18 segments were measured. Results The SRVmax in each group showed decreasing trend from the mitral annulus level, papillary muscle level to apical level, there was significant difference of each segment between 24 h group and 96 h group, 96 h group and 48 h group (P < 0.05),it showed increasing trend in the segments of 24 h group and 72 h group. There was no significant difference of SRSmax in each segment of all groups , while the SRSmax in papillary muscle level was significantly higher than that of apical level (P < 0.05). There was no significant difference of SCSmax in each segment of all groups, while the SCSmax inlevel of apex was higher than that of the mitral annulus (P < 0.05). Conclusion VVI can early detect neonatal small changes in left ventricular short-axis movement, it is a potientially useful tool for evaluating the systolic function of left ventricle in neonate.%目的 探讨速度向量成像技术(VVI )评价早期新生儿左室短轴运动变化的应用价值.方法 足月新生儿32例,分别在出生后第24 h、48 h、72 h及96 h应用VVI技术动态监测每例新生儿的左室短轴收缩运动,包括左室短轴18个节段的收缩期峰值径向运动速度(SRVmax)、峰值径向应变(SRSmax)及峰值圆周应变(SCSmax).结果 各组收缩期左室短轴方向的SRVmax在二尖瓣环水平、乳头肌水平及心尖水平呈现减小趋势,24 h组与96 h组各节段比较差异有统计学意义,24 h组与72 h组各节段比较呈增大趋势,96 h组与48 h

  13. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during May 2015 (NCEI Accession 0131932)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  14. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during February 2015 (NCEI Accession 0131074)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  15. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during June 2015 (NCEI Accession 0131956)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  16. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during April 2015 (NCEI Accession 0131908)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  17. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during March 2015 (NCEI Accession 0131884)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  18. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during June 2016 (NCEI Accession 0155978)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  19. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during January 2015 (NCEI Accession 0129913)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  20. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during December 2015 (NCEI Accession 0141105)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  1. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during January 2016 (NCEI Accession 0144286)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  2. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during March 2016 (NCEI Accession 0148078)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  3. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during May 2016 (NCEI Accession 0154389)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  4. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during April 2016 (NCEI Accession 0151726)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  5. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during February 2016 (NCEI Accession 0145743)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  6. The Importance of Velocity Acceleration to Flow-Mediated Dilation

    Directory of Open Access Journals (Sweden)

    Lee Stoner

    2012-01-01

    Full Text Available The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration, followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1 the limitations of using Posieuille's law to estimate shear stress and (2 the importance of the velocity profile—with emphasis on velocity acceleration—to endothelial function and vascular tone.

  7. Review of the correlation between blood flow velocity and polycythemia in the fetus, neonate and adult: appropriate diagnostic levels need to be determined for twin anemia-polycythemia sequence.

    Science.gov (United States)

    Lucewicz, A; Fisher, K; Henry, A; Welsh, A W

    2016-02-01

    Twin anemia-polycythemia sequence (TAPS) is recognized increasingly antenatally by the demonstration of an anemic twin and a polycythemic cotwin using the middle cerebral artery peak systolic velocity (MCA-PSV). While the MCA-PSV has been shown to correlate well with anemia in singleton fetuses, the evidence to support its use to diagnose fetal polycythemia appears to be less clear-cut. We aimed to evaluate fetal, neonatal and adult literature used to support the use of MCA-PSV for the diagnosis of polycythemia. Comprehensive literature searches were performed for ultrasound evidence of polycythemia in the human fetus, neonate and adult using key search terms. Only manuscripts in the English language with an abstract were considered for the review, performed in June 2014. Fifteen manuscripts were found for the human fetus, including 38 cases of TAPS. Nine of these defined fetal polycythemia as MCA-PSV < 0.8 multiples of the median (MoM), five used < 1.0 MoM and one used 0.8-1.0 MoM. Only two studies, involving a total of 15 cases, proposed a diagnostic level, acknowledging false-positive and -negative cases, though neither reported sensitivities or specificities. Six neonatal studies (96 neonates) demonstrated evidence of decreased cerebral velocities in polycythemia and a consequent increase with hemodilution. In the adult, five studies (57 polycythemic adults) demonstrated increased flow or velocity with hemodilution. Neither neonatal nor adult studies conclusively defined levels for screening for polycythemia. Despite widespread adoption of a cut-off of < 0.8 MoM in the published literature for the polycythemic fetus in TAPS, this is based upon minimal evidence, with unknown sensitivity and specificity. We recommend caution in excluding TAPS based purely upon the absence of a reduced MCA-PSV.

  8. Anaerobic critical velocity in four swimming techniques.

    Science.gov (United States)

    Neiva, H P; Fernandes, R J; Vilas-Boas, J P

    2011-03-01

    The aim of this study was to assess critical velocity in order to control and evaluate anaerobic swimming training. 51 highly trained male swimmers performed maximal 15, 25, 37.5 and 50 m in the 4 swimming techniques to determine critical velocity from the distance-time relationship. Anaerobic critical velocity was compared with 100 m swimming performance and corresponding partials. Complementarily, 9 swimmers performed a 6×50 m (4 min interval) training series at front crawl individual anaerobic critical velocity, capillary blood lactate concentrations being assessed after each repetition. The mean±SD values of anaerobic critical velocity and its relationship with the 100 m event were: 1.61±0.07 (r=0.60, p=0.037), 1.53±0.05 (r=0.81, p=0.015), 1.33±0.05 (r=0.83, p=0.002), and 1.75±0.05 (r=0.74, p=0.001), for butterfly, backstroke, breaststroke and front crawl, respectively. However, differences between anaerobic critical velocity and performance were observed (with exception of the second half of the 100 m swimming events in breaststroke and butterfly). Lactate concentration values at the end of the series were 14.52±1.06 mmol.l (-1), which suggests that it was indeed an anaerobic training set. In this sense, anaerobic critical velocity can be used to prescribe anaerobic training intensities.

  9. Polarization rotation locking of vector solitons in a fiber ring laser.

    Science.gov (United States)

    Zhao, L M; Tang, D Y; Zhang, H; Wu, X

    2008-07-07

    Polarization rotation of vector solitons in a fiber ring laser was experimentally studied. It was observed that the period of vector soliton polarization rotation could be locked to the cavity roundtrip time or multiple of it. We further show that multiple vector solitons can be formed in a fiber laser, and all the vector solitons have the same group velocity in cavity, however, their instantaneous polarization ellipse orientations could be orthogonal.

  10. Solving the Christoffel equation: Phase and group velocities

    Science.gov (United States)

    Jaeken, Jan W.; Cottenier, Stefaan

    2016-10-01

    We provide christoffel, a Python tool for calculating direction-dependent phase velocities, polarization vectors, group velocities, power flow angles and enhancement factors based on the stiffness tensor of a solid. It is built in a modular way to allow for efficient and flexible calculations, and the freedom to select and combine results as desired. All derivatives are calculated analytically, which circumvents possible numerical sampling problems. GNUPlot scripts are provided for convenient visualization.

  11. Visualizing 3D velocity fields near contour surfaces. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Max, N.; Crawfis, R.; Grant, C.

    1994-08-08

    Vector field rendering is difficult in 3D because the vector icons overlap and hide each other. We propose four different techniques for visualizing vector fields only near surfaces. The first uses motion blurred particles in a thickened region around the surface. The second uses a voxel grid to contain integral curves of the vector field. The third uses many antialiased lines through the surface, and the fourth uses hairs sprouting from the surface and then bending in the direction of the vector field. All the methods use the graphics pipeline, allowing real time rotation and interaction, and the first two methods can animate the texture to move in the flow determined by the velocity field.

  12. Visualizing 3D velocity fields near contour surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Max, N.; Crawfis, R.; Grant, C.

    1994-03-01

    Vector field rendering is difficult in 3D because the vector icons overlap and hide each other. We propose four different techniques for visualizing vector fields only near surfaces. The first uses motion blurred particles in a thickened region around the surface. The second uses a voxel grid to contain integral curves of the vector field. The third uses many antialiased lines through the surface, and the fourth uses hairs sprouting from the surface and then bending in the direction of the vector field. All the methods use the graphite pipeline, allowing real time rotation and interaction, and the first two methods can animate the texture to move in the flow determined by the velocity field.

  13. Vehicle Based Vector Sensor

    Science.gov (United States)

    2015-09-28

    300001 1 of 16 VEHICLE-BASED VECTOR SENSOR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...unmanned underwater vehicle that can function as an acoustic vector sensor . (2) Description of the Prior Art [0004] It is known that a propagating...mechanics. An acoustic vector sensor measures the particle motion via an accelerometer and combines Attorney Docket No. 300001 2 of 16 the

  14. Implicit Real Vector Automata

    Directory of Open Access Journals (Sweden)

    Jean-François Degbomont

    2010-10-01

    Full Text Available This paper addresses the symbolic representation of non-convex real polyhedra, i.e., sets of real vectors satisfying arbitrary Boolean combinations of linear constraints. We develop an original data structure for representing such sets, based on an implicit and concise encoding of a known structure, the Real Vector Automaton. The resulting formalism provides a canonical representation of polyhedra, is closed under Boolean operators, and admits an efficient decision procedure for testing the membership of a vector.

  15. Review of Scalars, Vectors, Tensors, and Dyads

    Science.gov (United States)

    Schnack, Dalton D.

    In MHD, we will deal with relationships between quantities such as the magnetic field and the velocity that have both magnitude and direction. These quantities are examples of vectors (or, as we shall soon see, pseudovectors). The basic concepts of scalar and vector quantities are introduced early in any scientific education. However, to formulate the laws of MHD precisely, it will be necessary to generalize these ideas and to introduce the less familiar concepts of matrices, tensors, and dyads. The ability to understand and manipulate these abstract mathematical concepts is essential to learning MHD. Therefore, for the sake of both reference and completeness, this lecture is about the mathematical properties of scalars, vectors, matrices, tensors, and dyads. If you are already an expert, or think you are, please skip class and go on to Lecture 3. You can always refer back here if needed!

  16. Complex Polynomial Vector Fields

    DEFF Research Database (Denmark)

    Dias, Kealey

    vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...... or meromorphic (allowing poles as singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic...

  17. Vectors and their applications

    CERN Document Server

    Pettofrezzo, Anthony J

    2005-01-01

    Geared toward undergraduate students, this text illustrates the use of vectors as a mathematical tool in plane synthetic geometry, plane and spherical trigonometry, and analytic geometry of two- and three-dimensional space. Its rigorous development includes a complete treatment of the algebra of vectors in the first two chapters.Among the text's outstanding features are numbered definitions and theorems in the development of vector algebra, which appear in italics for easy reference. Most of the theorems include proofs, and coordinate position vectors receive an in-depth treatment. Key concept

  18. Superluminal Recession Velocities

    CERN Document Server

    Davis, T M; Davis, Tamara M.; Lineweaver, Charles H.

    2000-01-01

    Hubble's Law, v=HD (recession velocity is proportional to distance), is a theoretical result derived from the Friedmann-Robertson-Walker metric. v=HD applies at least as far as the particle horizon and in principle for all distances. Thus, galaxies with distances greater than D=c/H are receding from us with velocities greater than the speed of light and superluminal recession is a fundamental part of the general relativistic description of the expanding universe. This apparent contradiction of special relativity (SR) is often mistakenly remedied by converting redshift to velocity using SR. Here we show that galaxies with recession velocities faster than the speed of light are observable and that in all viable cosmological models, galaxies above a redshift of three are receding superluminally.

  19. Determination of hearth position of a forthcoming strong EQ using gradients and phase velocities of ULF geomagnetic disturbances

    Science.gov (United States)

    Kopytenko, Yu. A.; Ismaguilov, V. S.; Hattori, K.; Hayakawa, M.

    Behavior of gradient and phase velocity vectors of ULF ( F 6) and 2003 ( M = 5.8) years. The gradient and phase velocity vectors were determined using the data of three high-sensitive three-component magnetic stations situated at a distance ∼5 km from each other (magnetic gradientometer). Two gradientometers were installed southeast and southwest of Tokyo at a distance ∼150 km from each other. It was found that the gradient and phase velocity values had anomaly changes 3-4 months before the strong EQs. New directions of the gradient vectors took place in the same period - the directions just to the forthcoming EQ epicenter. The directions from the forthcoming EQ epicenter arouse for the phase velocity vectors. We propose to use the gradient and phase velocity vectors of the ULF geomagnetic disturbances as important factors of the short-term prediction of strong earthquakes.

  20. Estimated carotid-femoral pulse wave velocity has similar predictive value as measured carotid-femoral pulse wave velocity

    DEFF Research Database (Denmark)

    Greve, Sara V; Blicher, Marie K; Kruger, Ruan;

    2016-01-01

    BACKGROUND: Carotid-femoral pulse wave velocity (cfPWV) adds significantly to traditional cardiovascular risk prediction, but is not widely available. Therefore, it would be helpful if cfPWV could be replaced by an estimated carotid-femoral pulse wave velocity (ePWV) using age and mean blood pres...

  1. Advancing vector biology research

    NARCIS (Netherlands)

    Kohl, Alain; Pondeville, Emilie; Schnettler, Esther; Crisanti, Andrea; Supparo, Clelia; Christophides, George K.; Kersey, Paul J.; Maslen, Gareth L.; Takken, Willem; Koenraadt, Constantianus J.M.; Oliva, Clelia F.; Busquets, Núria; Abad, F.X.; Failloux, Anna Bella; Levashina, Elena A.; Wilson, Anthony J.; Veronesi, Eva; Pichard, Maëlle; Arnaud Marsh, Sarah; Simard, Frédéric; Vernick, Kenneth D.

    2016-01-01

    Vector-borne pathogens impact public health, animal production, and animal welfare. Research on arthropod vectors such as mosquitoes, ticks, sandflies, and midges which transmit pathogens to humans and economically important animals is crucial for development of new control measures that target t

  2. Complex Polynomial Vector Fields

    DEFF Research Database (Denmark)

    The two branches of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions...... vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...... of parameter spaces into structurally stable domains, and a description of the bifurcations. For this reason, the talk will focus on these questions for complex polynomial vector fields....

  3. Complex Polynomial Vector Fields

    DEFF Research Database (Denmark)

    Dias, Kealey

    The two branches of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions...... or meromorphic (allowing poles as singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic...... vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...

  4. Advanced Ice Velocity Mapping Using Landsat 8

    Science.gov (United States)

    Klinger, M. J.; Scambos, T. A.; Fahnestock, M. A.; Haran, T. M.

    2014-12-01

    Improved image-to-image cross correlation software is applied to pairs of sequential Landsat 8 satellite imagery to accurately measure ice surface velocity over ice sheets and glaciers (±0.1 pixel displacement, 15 meter pixels). The high radiometric fidelity of Landsat 8's panchromatic band (12-bit), and exceptional geolocation accuracy (typically ±5 m) supports the generation of ice velocity fields over very short time intervals (e.g., 16-, 32-, or 48-day repeat images of the same scene location). The high radiometry supports velocity mapping in areas with very subtle topographic detail, including un-crevassed sastrugi regions on ice dome flanks or the ice sheet interior. New Python-based software presently under development (named PyCorr), takes two sequential Landsat 8 OLI scenes (or suitably processed ETM+ or TM scenes) and matches small sub-scenes ('chips') between the images based on similarity in their gray-scale value patterns, using an image correlation algorithm. Peak fitting in the region of maximum correlation for a chip pair yields sub-pixel fits to the feature offset vector. Vector editing after the image correlation runs seeks to eliminate spurious and cloud-impacted vectors, and correct residual geo-location error. This processing is based on plausible values of ice strain rates and known areas of near-zero ice flow (rock outcrops, ice dome areas, etc.). In preliminary processing, we have examined ~800 Landsat 8 image pairs having <20% cloud cover spanning the near-coastal Antarctic ice sheet during the 2013-14 summer season.

  5. Laser Doppler anemometer measurements using nonorthogonal velocity components: error estimates.

    Science.gov (United States)

    Orloff, K L; Snyder, P K

    1982-01-15

    Laser Doppler anemometers (LDAs) that are arranged to measure nonorthogonal velocity components (from which orthogonal components are computed through transformation equations) are more susceptible to calibration and sampling errors than are systems with uncoupled channels. In this paper uncertainty methods and estimation theory are used to evaluate, respectively, the systematic and statistical errors that are present when such devices are applied to the measurement of mean velocities in turbulent flows. Statistical errors are estimated for two-channel LDA data that are either correlated or uncorrelated. For uncorrelated data the directional uncertainty of the measured velocity vector is considered for applications where mean streamline patterns are desired.

  6. Non-Colinearity of Angular Velocity and Angular Momentum

    Science.gov (United States)

    Burr, A. F.

    1974-01-01

    Discusses the principles, construction, and operation of an apparatus which serves to demonstrate the non-colinearity of the angular velocity and momentum vectors as well as the inertial tensors. Applications of the apparatus to teaching of advanced undergraduate mechanics courses are recommended. (CC)

  7. Velocities in Solar Pores

    Science.gov (United States)

    Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.

    1996-05-01

    We investigate the three dimensional structure of solar pores and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around pores with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in pores increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the pores appear near these boundaries. We analyze the vertical velocity structure in pores and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for pores. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.

  8. 彩色多普勒超声监测生长迟缓胎儿脐动脉血液循环的变化%Color Doppler monitoring the blood flow velocity waveforms of the fetal umbilical artery of intrauterine growth retardation

    Institute of Scientific and Technical Information of China (English)

    黄子健; 潘素慈; 戴常平; 李秋明

    2001-01-01

    目的 应用彩色多普勒超声监测生长迟缓(IUGR)胎儿的脐动脉血液循环。方法 测定130例妊娠20~42周妇女(其中正常49例、IUGR 81例)脐动脉时间平均血流速度(TAMX)、收缩期最大血流速度与舒张末期血流速度的比值(S/D)、搏动指数(PI)、阻力指数(RI)、收缩期最大血流速度(Vmax)与舒张末期血流速度(Vmin)。结果 正常孕妇随孕龄增长,胎盘功能增强,胎儿血液循环日渐丰富。IUGR者则明显障碍,在20周时脐动脉TAMX显著下降,在30周后S/D、 PI及RI显著升高,Vmin显著下降,在35周时Vmax显著下降。出现舒张期血流停止或倒流。结论 彩色多普勒超声可直接测定脐动脉血液循环,能在早期诊断IUGR、判断病情及估计预后。%Objective To study the changes of the fetal circulation in intrauterine growth retardation (IUGR) cases.Methods Color Doppler ultrasound was used to detect blood flow velocity waveforms of the umbilical artery (UmA)in 130 pregnant women at 20~42 weeks′ gestation,of which 49 cases were normal pregnancy and 81 cases were IUGR.The indices included time average maximum (TAMX) ,pulsatility index (PI) , resistance index (RI) ,systolic maximum velocity (Vmax) /diastolic minimum velocity (Vmin) ratio (S/D).Results The results showed that the fetal circulation became abundant gradually with increasing gestational age in normal pregnancy group,but that TAMX was markedly decreased at 20 weeks′ gestation,S/D ratio,PI and RI were markedly elevated,Vmin was markedly decreased at 30 weeks′ gestation,and Vmax was markedly decreased at 35 weeks′ gestation in IUGR group.Conclusions Examining blood flow velocity waveforms of UmA by Color Doppler ultrasound was one of the best method to early diagnose and predict the prognosis of IUGR.

  9. Quantitative velocity modulation spectroscopy

    Science.gov (United States)

    Hodges, James N.; McCall, Benjamin J.

    2016-05-01

    Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined.

  10. Vector separation of particles and cells using an array of slanted open cavities

    CERN Document Server

    Bernate, Jorge A; Lagae, Liesbet; Konstantopoulo, Konstantinos; Drazer, German

    2014-01-01

    We present a microfluidic platform for the continuous separation of suspended particles based on their size and settling velocity. The separation method takes advantage of the flow field in the vicinity and inside a parallel array of slanted open cavities. These cavities induce flow along them, which deflects the suspended particles to a different degree depending on the extent to which they penetrate into the cavities. The cumulative deflection in the periodic array ultimately leads to vector chromatography, with the different species in the sample moving in different directions. We demonstrate density and size based separation over a range of flow rates by separating polystyrene and silica particles and show that purities nearing 100% can be achieved for multicomponent mixtures. We also demonstrate the potential of the platform to separate biological cells by fractionating different blood components. We discuss the presence of two regimes, which can be distinguished depending on the ratio between the settli...

  11. Cirrus Crystal Terminal Velocities.

    Science.gov (United States)

    Heymsfield, Andrew J.; Iaquinta, Jean

    2000-04-01

    Cirrus crystal terminal velocities are of primary importance in determining the rate of transport of condensate from upper- to middle-tropospheric levels and profoundly influence the earth's radiation balance through their effect on the rate of buildup or decay of cirrus clouds. In this study, laboratory and field-based cirrus crystal drag coefficient data, as well as analytical descriptions of cirrus crystal shapes, are used to derive more physically based expressions for the velocities of cirrus crystals than have been available in the past.Polycrystals-often bullet rosettes-are shown to be the dominant crystal types in synoptically generated cirrus, with columns present in varying but relatively large percentages, depending on the cloud. The two critical parameters needed to calculate terminal velocity are the drag coefficient and the ratio of mass to cross-sectional area normal to their fall direction. Using measurements and calculations, it is shown that drag coefficients from theory and laboratory studies are applicable to crystals of the types found in cirrus. The ratio of the mass to area, which is shown to be relatively independent of the number of bullets in the rosette, is derived from an analytic model that represents bullet rosettes containing one to eight bullets in 19 primary geometric configurations. The ratio is also derived for columns. Using this information, a general set of equations is developed to calculate the terminal velocities and masses in terms of the aspect ratio (width divided by length), ice density, and rosette maximum dimension. Simple expressions for terminal velocity and mass as a function of bullet rosette maximum dimension are developed by incorporating new information on bullet aspect ratios.The general terminal velocity and mass relations are then applied to a case from the First International Satellite Cloud Climatology Project (ISCCP) Research Experiment (FIRE) 2, when size spectra from a balloon-borne ice crystal

  12. The Prescribed Velocity Method

    DEFF Research Database (Denmark)

    Nielsen, Peter Vilhelm

    The- velocity level in a room ventilated by jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jets controls the air movement in the room and, therefore, it is very important that the inlet conditions and the numerical method can generate a satisfactory...... description of this momentum flow. The Prescribed Velocity Method is a practical method for the description of an Air Terminal Device which will save grid points close to the opening and ensure the right level of the momentum flow....

  13. Blood smear

    Science.gov (United States)

    ... some red blood cells shaped like spheres ( hereditary spherocytosis ) Increased breakdown of RBCs Presence of RBCs with ... normal Red blood cells, elliptocytosis Red blood cells, spherocytosis Acute lymphocytic leukemia - photomicrograph Red blood cells, multiple ...

  14. Blood culture

    Science.gov (United States)

    Culture - blood ... A blood sample is needed . The site where blood will be drawn is first cleaned with an antiseptic such ... organism from the skin getting into (contaminating) the blood sample and causing a false-positive result (see ...

  15. Blood Thinners

    Science.gov (United States)

    If you have some kinds of heart or blood vessel disease, or if you have poor blood flow to your brain, your doctor may recommend that you take a blood thinner. Blood thinners reduce the risk of heart ...

  16. Blood transfusions

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000431.htm Blood transfusions To use the sharing features on this ... several sources of blood which are described below. Blood From the Public (Volunteer Blood Donation) The most ...

  17. 速度向量成像结合潘生丁负荷在糖尿病大鼠心肌收缩功能评价中的应用价值%Value of velocity vector imaging and stress echocardiography in the assessment of systolic function of left ventricular in diabetic rats

    Institute of Scientific and Technical Information of China (English)

    卫张蕊; 张军; 张海滨; 苏海砾; 施红

    2010-01-01

    目的 探讨速度向量成像(VVI)技术结合潘生丁负荷试验是否可以早期检测糖尿病(DM)大鼠左室壁潜在的心肌功能障碍.方法 雄性SD大鼠18只,腹腔注射链脲菌素复制DM模型,另12只体质量匹配的雄性SD大鼠腹腔注射等量柠檬酸缓冲液作为对照.分别在静息状态和潘生丁负荷后,对两组大鼠(12周)乳头肌水平左室短轴观行VVI及M型超声心动图检查,分别测量潘生丁负荷前后乳头肌水平左室短轴观各个节段心肌最大收缩速度(Vs)、切向应变(εc)、径向应变(εr)、收缩期最大切向应变率(SRc)、径向应变率(SRr)及室壁增厚率的平均值.处死动物,摘除心脏,行HE染色及透射电镜检查.结果 静息状态下,DM组SRc较对照组显著减低(P<0.05),其余指标与对照组的差异无统计学意义.潘生丁负荷后,DM组各指标均较对照组显著减低(P<0.05).而M型检测的两组间室壁增厚率的差异并无统计学意义(P>0.05).结论 VVI与负荷超声心动图相结合,可以更敏感地检测出DM大鼠潜在的室壁运动异常.SRc可能是更为敏感的指标,其在静息状态下便可以检测出这种室壁运动的异常.%Objective To investigate whether velocity vector imaging (VVI) combined with stress echocardiography could detect potential myocardial impairment of the left ventricle(LV) in diabetic rats.Methods DM rats ( n = 18,administered by STZ at 65 mg/kg) and control rats( n = 12) were performed with VVI and M-mode echocardiography both at rest and after dipyridamole stress 12 weeks later. Twodimensional echocardiographic cine loops and M-mode images of three consecutive beats were obtained from the short-axis views at the mid-LV level. The means of segmental peak systolic velocity(Vs), circumferential strain(εc) ,radial strain(εr), systolic circumferential and radial strain rate (SRc, SRr) and the percent wall thickening (WT% ,derived from M-mode) were obtained. After echocardiograms

  18. Regional myocardium function in rabbit with acute myocardial ischemia assessed by velocity vector imaging%速度向量成像技术评价兔急性心肌缺血局部心肌功能的研究

    Institute of Scientific and Technical Information of China (English)

    周佳; 周启昌; 蒲大容; 刘红雨; 丁正东; 田蕾琪; 周嘉炜; 肖永志

    2011-01-01

    目的 建立新西兰大白兔急性心肌缺血的动物模型,应用速度向量成像(VVI)技术分析急性心肌缺血状态下左心室长轴和短轴方向上各节段局部心肌收缩功能的变化特点.方法 新西兰大白兔30只,随机分为冠状动脉结扎组和假手术组,于术前和术后30 min内行超声心动图检查并采集动态图像,脱机行VVI分析,测量左心室心肌各节段长轴和短轴方向上的VVI参数:收缩期峰值运动速度(Vs)、收缩期峰值应变(Ss)、收缩期峰值应变率(SRs),行统计学分析.结果 心肌缺血后,分别与术前及与假手术组比较,长轴方向上,前间隔心尖段与后壁心尖段的Vs明显减低;前间隔中间段、心尖段与后壁心尖段Ss、SRs明显减低,差异均有统计学意义(P<0.05);短轴方向上,前壁、侧壁的基底段,前间隔、前壁、侧壁的中间段和心尖水平的各节段的Vs明显减低;前间隔、前壁、侧壁的基底段,前间隔、前壁、侧壁、后壁的中间段以及心尖水平各节段的Ss、SRs明显减低,差异均有统计学意义(P<0.05).结论 急性心肌缺血后左心室支供血节段及部分相邻节段的长轴及短轴局部心肌收缩功能减低.VVI技术能够客观、准确的检测实验兔心肌长轴和短轴方向上局部运动功能的微小变化,为急性心肌缺血的早期诊断提供了一种新的无创的、可靠的定量工具.%Objective To utilize velocity vector imaging ( VVI ) in analyzing regional myocardium function within 30 minutes before and after myocardial ischemia induced by occlusion of coronary artery in New Zealand white rabbits and to evaluate the changes of longitudinal and brachydiagonal segmental left ventricular( LV ) systolic function in rabbits with acute myocardial ischemia. Methods Thirty New Zealand white rabbits were divided into groups of myocardial ischemia and sham operation. All rabbits were performed by echocardiography before the operation and after

  19. Can the curriculum be used to estimate critical velocity in young competitive swimmers?

    Science.gov (United States)

    Costa, Aldo M; Silva, António J; Louro, Hugo; Reis, Victor M; Garrido, Nuno D; Marques, Mário C; Marinho, Daniel A

    2009-01-01

    The aims of the present study were to assess critical velocity using the swimmer curriculum in front crawl events and to compare critical velocity to the velocity corresponding to a 4 mmol·l(-1) of blood lactate concentration and to the velocity of a 30 min test. The sample included 24 high level male swimmers ranged between 14 and 16 years old. For each subject the critical velocity, the velocity corresponding to a 4 mmol·l(-1) of blood lactate concentration and the mean velocity of a 30 min test were determined. The critical velocity was also estimated by considering the best performance of a swimmer over several distances based on the swimmer curriculum. Critical velocity including 100, 200 and 400 m events was not different from the velocity of 4 mmol·l(-1) of blood lactate concentration. Critical velocity including all the swimmer events was not different from the velocity of a 30 min test. The assessment of critical velocity based upon the swimmer curriculum would therefore seem to be a good approach to determine the aerobic ability of a swimmer. The selection of the events to be included in critical velocity assessment must be a main concern in the evaluation of the swimmer. Key pointsCritical velocity using 100, 200 and 400 m events was not different from the velocity of 4 mmol·l(-1) of blood lactate concentration.Critical velocity using all the swimmer events was not different from the velocity of a 30 min test.The assessment of critical velocity based upon the swimmer curriculum seemed to be a good approach to determine the aerobic capacity of a swimmer.The decision on the events to be analysed must be a main concern in the evaluation of the swimmer critical velocity.

  20. ON VECTOR NETWORK EQUILIBRIUM PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Guangya CHEN

    2005-01-01

    In this paper we define a concept of weak equilibrium for vector network equilibrium problems.We obtain sufficient conditions of weak equilibrium points and establish relation with vector network equilibrium problems and vector variational inequalities.

  1. Modeling Terminal Velocity

    Science.gov (United States)

    Brand, Neal; Quintanilla, John A.

    2013-01-01

    Using a simultaneously falling softball as a stopwatch, the terminal velocity of a whiffle ball can be obtained to surprisingly high accuracy with only common household equipment. This classroom activity engages students in an apparently daunting task that nevertheless is tractable, using a simple model and mathematical techniques at their…

  2. Tagged Vector Contour (TVC)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas Tagged Vector Contour (TVC) dataset consists of digitized contours from the 7.5 minute topographic quadrangle maps. Coverage for the state is incomplete....

  3. GAP Land Cover - Vector

    Data.gov (United States)

    Minnesota Department of Natural Resources — This vector dataset is a detailed (1-acre minimum), hierarchically organized vegetation cover map produced by computer classification of combined two-season pairs of...

  4. Noncausal Bayesian Vector Autoregression

    DEFF Research Database (Denmark)

    Lanne, Markku; Luoto, Jani

    We propose a Bayesian inferential procedure for the noncausal vector autoregressive (VAR) model that is capable of capturing nonlinearities and incorporating effects of missing variables. In particular, we devise a fast and reliable posterior simulator that yields the predictive distribution...

  5. Vector Lattice Vortex Solitons

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Dong; YE Fang-Wei; DONG Liang-Wei; LI Yong-Ping

    2005-01-01

    @@ Two-dimensional vector vortex solitons in harmonic optical lattices are investigated. The stability properties of such solitons are closely connected to the lattice depth Vo. For small Vo, vector vortex solitons with the total zero-angular momentum are more stable than those with the total nonzero-angular momentum, while for large Vo, this case is inversed. If Vo is large enough, both the types of such solitons are stable.

  6. Support vector machines applications

    CERN Document Server

    Guo, Guodong

    2014-01-01

    Support vector machines (SVM) have both a solid mathematical background and good performance in practical applications. This book focuses on the recent advances and applications of the SVM in different areas, such as image processing, medical practice, computer vision, pattern recognition, machine learning, applied statistics, business intelligence, and artificial intelligence. The aim of this book is to create a comprehensive source on support vector machine applications, especially some recent advances.

  7. The Vector Curvaton

    CERN Document Server

    Navarro, Andres A

    2013-01-01

    We analyze a massive vector field with a non-canonical kinetic term in the action, minimally coupled to gravity, where the mass and kinetic function of the vector field vary as functions of time during inflation. The vector field is introduced following the same idea of a scalar curvaton, which must not affect the inflationary dynamics since its energy density during inflation is negligible compared to the total energy density in the Universe. Using this hypothesis, the vector curvaton will be solely responsible for generating the primordial curvature perturbation \\zeta. We have found that the spectra of the vector field perturbations are scale-invariant in superhorizon scales due to the suitable choice of the time dependence of the kinetic function and the effective mass during inflation. The preferred direction, generated by the vector field, makes the spectrum of \\zeta depend on the wavevector, i.e. there exists statistical anisotropy in \\zeta. This is discussed principally in the case where the mass of th...

  8. Wave propagation and group velocity

    CERN Document Server

    Brillouin, Léon

    1960-01-01

    Wave Propagation and Group Velocity contains papers on group velocity which were published during the First World War and are missing in many libraries. It introduces three different definitions of velocities: the group velocity of Lord Rayleigh, the signal velocity of Sommerfeld, and the velocity of energy transfer, which yields the rate of energy flow through a continuous wave and is strongly related to the characteristic impedance. These three velocities are identical for nonabsorbing media, but they differ considerably in an absorption band. Some examples are discussed in the last chapter

  9. Apparatus and method for determining movements and velocities of moving objects

    DEFF Research Database (Denmark)

    1998-01-01

    (M) elements. The transmit beam former and the receive beam former are configured to obtain the spatially oscillating field. The signal received from the interacting objects (4) is processed by the velocity estimator processor (7) for calculation of the velocity vector components by estimating the shift...

  10. Non-Maxwellian Electron Velocity Distributions Observed with Thomson Scattering in the Tortur Tokamak

    NARCIS (Netherlands)

    van Lammeren, A. C. A. P.; Barth, C. J.; Vanest, Q. C.; Schüller, F. C.

    1992-01-01

    The Thomson scattering spectrum represents the projection of the three-dimensional electron velocity distribution on the scattering vector. From this the local electron temperature and density can be derived. To determine the three-dimensional electron velocity distribution it is necessary to have s

  11. The calibration of (multi-)hot-wire probes. 2. Velocity-calibration

    NARCIS (Netherlands)

    Dijk, van A.; Nieuwstadt, F.T.M.

    2004-01-01

    We review a set of velocity calibration methods for one popular configuration of a four-hot-wire probe with the aim of finding a method of estimating with 10% accuracy (based on full scale) the mean flow vector, the rms of the turbulent velocity component and the associated linearized anisotropy inv

  12. Radial Velocities with PARAS

    Science.gov (United States)

    Roy, Arpita; Mahadevan, S.; Chakraborty, A.; Pathan, F. M.; Anandarao, B. G.

    2010-01-01

    The Physical Research Laboratory Advanced Radial-velocity All-sky Search (PARAS) is an efficient fiber-fed cross-dispersed high-resolution echelle spectrograph that will see first light in early 2010. This instrument is being built at the Physical Research laboratory (PRL) and will be attached to the 1.2m telescope at Gurushikhar Observatory at Mt. Abu, India. PARAS has a single-shot wavelength coverage of 370nm to 850nm at a spectral resolution of R 70000 and will be housed in a vacuum chamber (at 1x10-2 mbar pressure) in a highly temperature controlled environment. This renders the spectrograph extremely suitable for exoplanet searches with high velocity precision using the simultaneous Thorium-Argon wavelength calibration method. We are in the process of developing an automated data analysis pipeline for echelle data reduction and precise radial velocity extraction based on the REDUCE package of Piskunov & Valenti (2002), which is especially careful in dealing with CCD defects, extraneous noise, and cosmic ray spikes. Here we discuss the current status of the PARAS project and details and tests of the data analysis procedure, as well as results from ongoing PARAS commissioning activities.

  13. Vector cross product in n-dimensional vector space

    OpenAIRE

    Tian, Xiu-Lao; Yang, Chao; Hu, Yang; Tian, Chao

    2013-01-01

    The definition of vector cross product (VCP) introduced by Eckmann only exists in thethree- and the seven- dimensional vector space. In this paper, according to the orthogonal completeness, magnitude of basis vector cross product and all kinds of combinations of basis vector $\\hat{e}_i$, the generalized definition of VCP in the odd n-dimensional vector space is given by introducing a cross term $X_{AB}$. In addition, the definition is validated by reducing the generalization definition to the...

  14. CAN THE CURRICULUM BE USED TO ESTIMATE CRITICAL VELOCITY IN YOUNG COMPETITIVE SWIMMERS?

    Directory of Open Access Journals (Sweden)

    Daniel A. Marinho

    2009-03-01

    Full Text Available The aims of the present study were to assess critical velocity using the swimmer curriculum in front crawl events and to compare critical velocity to the velocity corresponding to a 4 mmol·l-1 of blood lactate concentration and to the velocity of a 30 min test. The sample included 24 high level male swimmers ranged between 14 and 16 years old. For each subject the critical velocity, the velocity corresponding to a 4 mmol·l-1 of blood lactate concentration and the mean velocity of a 30 min test were determined. The critical velocity was also estimated by considering the best performance of a swimmer over several distances based on the swimmer curriculum. Critical velocity including 100, 200 and 400 m events was not different from the velocity of 4 mmol·l-1 of blood lactate concentration. Critical velocity including all the swimmer events was not different from the velocity of a 30 min test. The assessment of critical velocity based upon the swimmer curriculum would therefore seem to be a good approach to determine the aerobic ability of a swimmer. The selection of the events to be included in critical velocity assessment must be a main concern in the evaluation of the swimmer

  15. Magnetic-resonance velocity mapping of the central circulation

    DEFF Research Database (Denmark)

    Søndergaard, Lise

    1994-01-01

    In magnetic-resonance (MR) velocity mapping there exists a linear relationship between the velocity and signal in each element of a tomographic image. The technique can be used for quantitative measurements of linear velocities (m s-1) and flow rates (1 min-1). By using cinematographic images...... the flow profile during the cardiac cycle can be determined. This allows quantification of forward flow, regurgitant volume and regurgitant fraction in cases of heart-valve insufficiency. In valvular stenosis the transvalvular pressure gradient and valve area can be determined. Magnetic-resonance velocity...... mapping may also provide information about diastolic function of left ventricular function. Together with other MR imaging techniques, velocity mapping gives an accurate assessment of the severity of aortic dissection. Recent studies indicate that MR velocity mapping provides quantification of renal blood...

  16. Extended Mixed Vector Equilibrium Problems

    Directory of Open Access Journals (Sweden)

    Mijanur Rahaman

    2014-01-01

    Full Text Available We study extended mixed vector equilibrium problems, namely, extended weak mixed vector equilibrium problem and extended strong mixed vector equilibrium problem in Hausdorff topological vector spaces. Using generalized KKM-Fan theorem (Ben-El-Mechaiekh et al.; 2005, some existence results for both problems are proved in noncompact domain.

  17. 速度向量成像技术评价犬心肌缺血与梗死状态下左心室节段性旋转特征%Assessment of regional rotation by velocity vector imaging in canine with myocardial ischemia and acute myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    张晓娟; 智光

    2011-01-01

    Objective To assess the regional rotation in canine with myocardial ischemia and acute myocardial infarction by velocity vector imaging( VVI ).Methods Myocardial ischemia and infarction model were successfully made by partly and fully ligating the left anterior descending coronary artery ( LAD ) in twelve mongrel dogs. The ventricle rotation and strain were measured by VVI. Results The results revealed: The LAD part ligation: rotation decreased in ventricular septal before LAD ligation status in LAD part ligation status( P <0. 05 ). The strain and strain rate has no significant difference. The LAD ful ligation: the rotation rate, rotation, circumferential strain and strain rate of the anterior septal, anterior wall and ventricular septal were significantly decreased in myocardial infarction status compared with those in the normal status, and were also significantly decreased compared with those in the myocardial ischemia status( P <0. 05 ). The strain and strain rate in the anterior septal,anterior wall and ventricular septal were significantly decreased in myocardial infarction status compared with those in the normal status( P <0. 05 ), but not significantly decreased compared with those in partly ligation status. Conclusion VVI can non-invasively and sensitively assess the left ventricular rotation and the results indicated the ventricular rotation is more sensitive than the strain and strain rate in evaluation of the ventricular systolic function.%目的 应用速度向量成像(VVI)技术评价心肌缺血及心肌梗死状态下犬心肌旋转运动特征.方法 选用杂种犬12只,在超声实时引导下结扎前降支定量制备前降支轻度狭窄(狭窄率:50%~75%)与完全闭塞模型,应用VVI技术分析前降支结扎前、轻度狭窄与完全闭塞状态下左心室旋转特征的改变.结果 12只杂种犬成功制备前降支轻度狭窄与完全闭塞模型,应用VVI技术对缺血与梗死状态下心肌旋

  18. Blood Donation

    Science.gov (United States)

    Tests and Procedures Blood donation By Mayo Clinic Staff Blood donation is a voluntary procedure. You agree to have blood drawn so that it can ... have a disease that requires blood components. Blood donation makes all of this possible. There are several ...

  19. Bunyavirus-vector interactions.

    Science.gov (United States)

    Beaty, B J; Bishop, D H

    1988-06-01

    Recent advances in the genetics and molecular biology of bunyaviruses have been applied to understanding bunyavirus-vector interactions. Such approaches have revealed which virus gene and gene products are important in establishing infections in vectors and in transmission of viruses. However, much more information is required to understand the molecular mechanisms of persistent infections of vectors which are lifelong but apparently exert no untoward effect. In fact, it seems remarkable that LAC viral antigen can be detected in almost every cell in an ovarian follicle, yet no untoward effect on fecundity and no teratology is seen. Similarly the lifelong infection of the vector would seem to provide ample opportunity for bunyavirus evolution by genetic drift and, under the appropriate circumstances, by segment reassortment. The potential for bunyavirus evolution by segment reassortment in vectors certainly exists. For example the Group C viruses in a small forest in Brazil seem to constitute a gene pool, with the 6 viruses related alternately by HI/NT and CF reactions, which assay respectively M RNA and S RNA gene products (Casals and Whitman, 1960; Shope and Causey, 1962). Direct evidence for naturally occurring reassortant bunyaviruses has also been obtained. Oligonucleotide fingerprint analyses of field isolates of LAC virus and members of the Patois serogroup of bunyaviruses have demonstrated that reassortment does occur in nature (El Said et al., 1979; Klimas et al., 1981; Ushijima et al., 1981). Determination of the genotypic frequencies of viruses selected by the biological interactions of viruses and vectors after dual infection and segment reassortment is an important issue. Should a virus result that efficiently interacts with alternate vector species, the virus could be expressed in different circumstances with serious epidemiologic consequences. Dual infection of vectors with different viruses is not unlikely, because many bunyaviruses are sympatric in

  20. Preliminary examples of 3D vector flow imaging

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev

    2013-01-01

    This paper presents 3D vector flow images obtained using the 3D Transverse Oscillation (TO) method. The method employs a 2D transducer and estimates the three velocity components simultaneously, which is important for visualizing complex flow patterns. Data are acquired using the experimental ult...

  1. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during August 2016 (NCEI Accession 0156623)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  2. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during August 2015 (NCEI Accession 0131989)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  3. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during October 2015 (NCEI Accession 0138228)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  4. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during November 2015 (NCEI Accession 0139551)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  5. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during September 2015 (NCEI Accession 0137285)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  6. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during July 2016 (NCEI Accession 0156399)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  7. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during July 2015 (NCEI Accession 0131976)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  8. Vector Fields on Product Manifolds

    CERN Document Server

    Kurz, Stefan

    2011-01-01

    This short report establishes some basic properties of smooth vector fields on product manifolds. The main results are: (i) On a product manifold there always exists a direct sum decomposition into horizontal and vertical vector fields. (ii) Horizontal and vertical vector fields are naturally isomorphic to smooth families of vector fields defined on the factors. Vector fields are regarded as derivations of the algebra of smooth functions.

  9. Doppler transcraniano convencional em voluntários assintomáticos: variabilidade e valores de referência para parâmetros de fluxo sanguíneo Reference values for measures of blood flow velocities and impedance indexes in healthy individuals through conventional transcranial Doppler

    Directory of Open Access Journals (Sweden)

    Maurício Fregonesi Barbosa

    2006-09-01

    Full Text Available OBJETIVO: Estabelecer valores de referência para medidas de velocidade sanguínea e índices de impedância em indivíduos saudáveis por meio do Doppler transcraniano convencional (DTC e observar suas variações em relação à idade e sexo. MÉTODO: Foram examinados 88 voluntários assintomáticos, sem antecedentes de doença cerebrovascular, cardíaca ou vascular periférica. Os exames de DTC foram realizados pelo mesmo examinador, sendo as artérias cerebrais médias, anteriores e posteriores estudadas por meio da janela temporal e as artérias vertebrais e basilar por meio da janela suboccipital. Foram arquivados os valores de velocidade média (VM, velocidade de pico sistólico (VPS, velocidade diastólica final (VDF e índices de resistência (IR e pulsatilidade (IP de cada segmento arterial examinado. RESULTADOS: Os limites de referência encontrados por nós foram semelhantes aos descritos por outros autores para todos os parâmetros estudados. Houve tendência das velocidades de fluxo diminuírem e dos índices de impedância aumentarem com o avançar da idade. Os valores de velocidade nas mulheres foram superiores aos encontrados em homens. CONCLUSÃO: O DTC se mostrou útil na avaliação hemodinâmica cerebral de nossa população. Os nossos resultados são semelhantes aos de outros estudos, tanto nos valores de referência quanto na sua relação com a idade e o sexo.OBJECTIVE: To establish reference values for measures of blood flow velocities and impedance indexes in healthy individuals through conventional transcranial Doppler (TCD and to observe their variations in relation to the age and sex. METHOD: 88 asymptomatic volunteers were examined without antecedents of cardiac, peripheral or cerebrovascular diseases. The TCD were accomplished by the same examiner. The middle, anterior and posterior cerebral arteries were studied through the temporal acoustic window and the vertebral and basilar arteries through the suboccipital

  10. Laser transit anemometer measurements of a JANNAF nozzle base velocity flow field

    Science.gov (United States)

    Hunter, William W., Jr.; Russ, C. E., Jr.; Clemmons, J. I., Jr.

    1990-01-01

    Velocity flow fields of a nozzle jet exhausting into a supersonic flow were surveyed. The measurements were obtained with a laser transit anemometer (LTA) system in the time domain with a correlation instrument. The LTA data is transformed into the velocity domain to remove the error that occurs when the data is analyzed in the time domain. The final data is shown in velocity vector plots for positions upstream, downstream, and in the exhaust plane of the jet nozzle.

  11. Boosting Support Vector Machines

    Directory of Open Access Journals (Sweden)

    Elkin Eduardo García Díaz

    2006-11-01

    Full Text Available En este artículo, se presenta un algoritmo de clasificación binaria basado en Support Vector Machines (Máquinas de Vectores de Soporte que combinado apropiadamente con técnicas de Boosting consigue un mejor desempeño en cuanto a tiempo de entrenamiento y conserva características similares de generalización con un modelo de igual complejidad pero de representación más compacta./ In this paper we present an algorithm of binary classification based on Support Vector Machines. It is combined with a modified Boosting algorithm. It run faster than the original SVM algorithm with a similar generalization error and equal complexity model but it has more compact representation.

  12. Robustifying Vector Median Filter

    Directory of Open Access Journals (Sweden)

    Valentín Gregori

    2011-08-01

    Full Text Available This paper describes two methods for impulse noise reduction in colour images that outperform the vector median filter from the noise reduction capability point of view. Both methods work by determining first the vector median in a given filtering window. Then, the use of complimentary information from componentwise analysis allows to build robust outputs from more reliable components. The correlation among the colour channels is taken into account in the processing and, as a result, a more robust filter able to process colour images without introducing colour artifacts is obtained. Experimental results show that the images filtered with the proposed method contain less noisy pixels than those obtained through the vector median filter. Objective measures demonstrate the goodness of the achieved improvement.

  13. Donating Blood

    Science.gov (United States)

    ... can't get an infection or disease from giving blood. The needles and other equipment used are sterile ... part of blood (plasma) within 72 hours after giving blood. It generally takes about 4–8 weeks to ...

  14. Calculation and analysis of velocity and viscous drag in an artery with a periodic pressure gradient

    Science.gov (United States)

    Alizadeh, M.; Seyedpour, S. M.; Mozafari, V.; Babazadeh, Shayan S.

    2012-07-01

    Blood as a fluid that human and other living creatures are dependent on has been always considered by scientists and researchers. Any changes in blood pressure and its normal velocity can be a sign of a disease. Whatever significant in blood fluid's mechanics is Constitutive equations and finding some relations for analysis and description of drag, velocity and periodic blood pressure in vessels. In this paper, by considering available experimental quantities, for blood pressure and velocity in periodic time of a thigh artery of a living dog, at first it is written into Fourier series, then by solving Navier-Stokes equations, a relation for curve drawing of vessel blood pressure with rigid wall is obtained. Likewise in another part of this paper, vessel wall is taken in to consideration that vessel wall is elastic and its pressure and velocity are written into complex Fourier series. In this case, by solving Navier-Stokes equations, some relations for blood velocity, viscous drag on vessel wall and blood pressure are obtained. In this study by noting that vessel diameter is almost is large (3.7 mm), and blood is considered as a Newtonian fluid. Finally, available experimental quantities of pressure with obtained curve of solving Navier-Stokes equations are compared. In blood analysis in rigid vessel, existence of 48% variance in pressure curve systole peak caused vessel blood flow analysis with elastic wall, results in new relations for blood flow description. The Resultant curve is obtained from new relations holding 10% variance in systole peak.

  15. Transverse velocity shifts in protostellar jets: rotation or velocity asymmetries?

    CERN Document Server

    De Colle, Fabio; Riera, Angels

    2016-01-01

    Observations of several protostellar jets show systematic differences in radial velocity transverse to the jet propagation direction, which have been interpreted as evidence of rotation in the jets. In this paper we discuss the origin of these velocity shifts, and show that they could be originated by rotation in the flow, or by side to side asymmetries in the shock velocity, which could be due to asymmetries in the jet ejection velocity/density or in the ambient medium. For typical poloidal jet velocities (~ 100-200 km/s), an asymmetry >~ 10% can produce velocity shifts comparable to those observed. We also present three dimensional numerical simulations of rotating, precessing and asymmetric jets, and show that, even though for a given jet there is a clear degeneracy between these effects, a statistical analysis of jets with different inclination angles can help to distinguish between the alternative origins of transverse velocity shifts. Our analysis indicate that side to side velocities asymmetries could ...

  16. The teaching of vectors in mathematics and physics in France during the 20th century

    OpenAIRE

    Ba, Cissé; Dorier, Jean-Luc

    2010-01-01

    The work presented in this text is part of a doctorial dissertation in mathematics education (Ba 2006) about the teaching and learning of vectors, translations, forces, velocity and movement of translation in mathematics and physics. Here, we present the evolution of the teaching of vectors and vector quantities in mathematics and physics from the end of the 19th century up to now. We analyse this evolution in the light of the ecology of knowledge, as developed by Yves Chevallard (1994). This...

  17. Environmental Acoustics and Intensity Vector Acoustics with Emphasis on Shallow Water Effects and the Sea Surface

    Science.gov (United States)

    2014-09-30

    Vector Acoustics with Emphasis on Shallow Water Effects and the Sea Surface Peter H. Dahl Applied Physics Laboratory University of Washington...To understand and predict key properties of the signal intensity vector field as it propagates away from an active sound source, with emphasis is on...exploit acoustic vector field properties (velocity, acceleration, intensity) much more than today’s. Furthermore, advancement of current Navy

  18. Matrix vector analysis

    CERN Document Server

    Eisenman, Richard L

    2005-01-01

    This outstanding text and reference applies matrix ideas to vector methods, using physical ideas to illustrate and motivate mathematical concepts but employing a mathematical continuity of development rather than a physical approach. The author, who taught at the U.S. Air Force Academy, dispenses with the artificial barrier between vectors and matrices--and more generally, between pure and applied mathematics.Motivated examples introduce each idea, with interpretations of physical, algebraic, and geometric contexts, in addition to generalizations to theorems that reflect the essential structur

  19. Free topological vector spaces

    OpenAIRE

    Gabriyelyan, Saak S.; Morris, Sidney A.

    2016-01-01

    We define and study the free topological vector space $\\mathbb{V}(X)$ over a Tychonoff space $X$. We prove that $\\mathbb{V}(X)$ is a $k_\\omega$-space if and only if $X$ is a $k_\\omega$-space. If $X$ is infinite, then $\\mathbb{V}(X)$ contains a closed vector subspace which is topologically isomorphic to $\\mathbb{V}(\\mathbb{N})$. It is proved that if $X$ is a $k$-space, then $\\mathbb{V}(X)$ is locally convex if and only if $X$ is discrete and countable. If $X$ is a metrizable space it is shown ...

  20. Duality in vector optimization

    CERN Document Server

    Bot, Radu Ioan

    2009-01-01

    This book presents fundamentals and comprehensive results regarding duality for scalar, vector and set-valued optimization problems in a general setting. After a preliminary chapter dedicated to convex analysis and minimality notions of sets with respect to partial orderings induced by convex cones a chapter on scalar conjugate duality follows. Then investigations on vector duality based on scalar conjugacy are made. Weak, strong and converse duality statements are delivered and connections to classical results from the literature are emphasized. One chapter is exclusively consecrated to the s

  1. Scalar-Vector Bootstrap

    CERN Document Server

    Rejon-Barrera, Fernando

    2015-01-01

    We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.

  2. Topological vector spaces

    CERN Document Server

    Narici, Lawrence

    2011-01-01

    BackgroundTopology Valuation Theory Algebra Linear Functionals Hyperplanes Measure Theory Normed SpacesCommutative Topological GroupsElementary ConsiderationsSeparation and Compactness Bases at 0 for Group Topologies Subgroups and Products Quotients S-Topologies Metrizability CompletenessCompleteness Function Groups Total BoundednessCompactness and Total Boundedness Uniform Continuity Extension of Uniformly Continuous Maps CompletionTopological Vector SpacesAbsorbent and Balanced Sets Convexity-AlgebraicBasic PropertiesConvexity-Topological Generating Vector Topologies A Non-Locally Convex Spa

  3. 人胰岛素样生长因子1基因质粒载体的构建及其在人脐血源性神经干细胞中的表达%Construction of Plasmid Vector Containing Human Insulin-Like Growth Factor 1 and Its Expression in Human Umbilical Cord Blood-Derived Neural Stem Cells

    Institute of Scientific and Technical Information of China (English)

    王军; 吴值荣; 朱登纳; 高峰; 侯艳艳; 陈海; 王留霞

    2011-01-01

    Objective To construct the plasmid expression vector containing human insulin - like growth factor 1 ( IGF - 1 ), and examine the expression of IGF - 1 gene in human umbilical cord blood - derived neural stem cells(NSCs).Methods The IGF - 1 gene was extracted from the fetal liver via reverse tranacription polymerase chain reaction( RT - PCR) ,then the product of PCR and plasmid pcDNA3.1 were purified by gel extraction.After enzyme digestion of DNA restriction enzyme - BamH Ⅰ and Hind Ⅲ, purified IGF - 1 gene was cloned into expression plasmid vector pcDNA3.1 by T4 DNA Ligase.Recombinant plasmid was identified by DNA sequencing method and enzyme digestion of DNA restriction enzyme - BamH Ⅰ and Hind Ⅲ.Recombinant pcDNA3.1 - IGF - 1 and empty plasmid were transfected into human umbilical cord blood - derived NSCs through lipofectin transfection.After transfection, transfected umbilical cord blood - derived NSCs were filtered with neomycin( G418 ).The expression of IGF - 1 gene in the gene transfected umbilical cord blood - derived was examined by immunocytochemical method and RT - PCR.Results IGF - 1 gene was successfully extracted from the fetal liver.Recombinants peDNA3.1 -IGF - 1 was proved accurate by restriction enzyme digestion and sequencing.Recombinant was transfected into human umbilical cord blood -derived NSCs by liposome for 24 hours,then selection cell clones appeared after 2 weeks for G418 filtering.In umbilical cord blood -derived NSCs transfected by recombinant plasmid vector, the expression of IGF- 1 gene was successful, which was detected by immtmocyto-chemical method and the expression of IGF - 1 mRNA was also positive while the other was negative compared with controla,which was examined by RT - PCR.Conclusion IGF - 1 gene can expressed in umbilical cord blood - derived NSCs transfected by recombinant plasmid vector.%目的 构建人胰岛素样生长因子1(IGF-1)质粒表达载体,并观察重组体pcDNA3.1-IGF-1转染后的脐血

  4. Tomographic Particle Localization and Velocity Measurement

    Science.gov (United States)

    Kirner, S.; Forster, G.; Schein, J.

    2015-01-01

    Wire arc spraying is one of the most common and elementary thermal spray processes. Due to its easy handling, high deposition rate, and relative low process costs, it is a frequently used coating technology for the production of wear and corrosion resistant coatings. In order to produce reliable and reproducible coatings, it is necessary to be able to control the coating process. This can be achieved by analyzing the parameters of the particles deposited. Essential for the coating quality are, for example, the velocity, the size, and the temperature of the particles. In this work, an innovative diagnostic for particle velocity and location determination is presented. By the use of several synchronized CMOS-Cameras positioned around the particle jet, a series of images from different directions is simultaneously taken. The images contain the information that is necessary to calculate the 3D-location-vector of the particles and finally with the help of the exposure time the trajectory can be determined. In this work, the experimental setup of the tomographic diagnostic is presented, the mathematical method of the reconstruction is explained, and first measured velocity distributions are shown.

  5. Minimum Length - Maximum Velocity

    CERN Document Server

    Panes, Boris

    2011-01-01

    We study a framework where the hypothesis of a minimum length in space-time is complemented with the notion of reference frame invariance. It turns out natural to interpret the action of the obtained reference frame transformations in the context of doubly special relativity. As a consequence of this formalism we find interesting connections between the minimum length properties and the modified velocity-energy relation for ultra-relativistic particles. For example we can predict the ratio between the minimum lengths in space and time using the results from OPERA about superluminal neutrinos.

  6. Dark Matter Velocity Spectroscopy

    CERN Document Server

    Speckhard, Eric G; Beacom, John F; Laha, Ranjan

    2016-01-01

    Dark matter decays or annihilations that produce line-like spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming and proposed experiments will make significant improvements. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.

  7. Dark Matter Velocity Spectroscopy.

    Science.gov (United States)

    Speckhard, Eric G; Ng, Kenny C Y; Beacom, John F; Laha, Ranjan

    2016-01-22

    Dark matter decays or annihilations that produce linelike spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming experiments will have the precision needed. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.

  8. Accelerated radial Fourier-velocity encoding using compressed sensing

    Energy Technology Data Exchange (ETDEWEB)

    Hilbert, Fabian; Han, Dietbert [Wuerzburg Univ. (Germany). Inst. of Radiology; Wech, Tobias; Koestler, Herbert [Wuerzburg Univ. (Germany). Inst. of Radiology; Wuerzburg Univ. (Germany). Comprehensive Heart Failure Center (CHFC)

    2014-10-01

    Purpose:Phase Contrast Magnetic Resonance Imaging (MRI) is a tool for non-invasive determination of flow velocities inside blood vessels. Because Phase Contrast MRI only measures a single mean velocity per voxel, it is only applicable to vessels significantly larger than the voxel size. In contrast, Fourier Velocity Encoding measures the entire velocity distribution inside a voxel, but requires a much longer acquisition time. For accurate diagnosis of stenosis in vessels on the scale of spatial resolution, it is important to know the velocity distribution of a voxel. Our aim was to determine velocity distributions with accelerated Fourier Velocity Encoding in an acquisition time required for a conventional Phase Contrast image. Materials and Methods:We imaged the femoral artery of healthy volunteers with ECG - triggered, radial CINE acquisition. Data acquisition was accelerated by undersampling, while missing data were reconstructed by Compressed Sensing. Velocity spectra of the vessel were evaluated by high resolution Phase Contrast images and compared to spectra from fully sampled and undersampled Fourier Velocity Encoding. By means of undersampling, it was possible to reduce the scan time for Fourier Velocity Encoding to the duration required for a conventional Phase Contrast image. Results:Acquisition time for a fully sampled data set with 12 different Velocity Encodings was 40 min. By applying a 12.6 - fold retrospective undersampling, a data set was generated equal to 3:10 min acquisition time, which is similar to a conventional Phase Contrast measurement. Velocity spectra from fully sampled and undersampled Fourier Velocity Encoded images are in good agreement and show the same maximum velocities as compared to velocity maps from Phase Contrast measurements. Conclusion: Compressed Sensing proved to reliably reconstruct Fourier Velocity Encoded data. Our results indicate that Fourier Velocity Encoding allows an accurate determination of the velocity

  9. Effect of head-up tilt on cerebral blood flow velocity during general anesthesla in patients with diabetic neuropathy%头高位对糖尿病并发自主神经病变患者全麻下脑血流速度的影响

    Institute of Scientific and Technical Information of China (English)

    王宏伟; 钟泰迪

    2012-01-01

    目的 评价头高位对糖尿病并发自主神经病变患者全麻下脑血流速度的影响.方法 择期行全麻手术患者60例,ASA分级Ⅰ或Ⅱ级,年龄40~60岁,体重52 ~70 kg,按照合并糖尿病情况,将患者分为3组:非糖尿病患者对照组(C组)、无自主神经病变的糖尿病组(D组)和糖尿病并发自主神经病变组(ANS-D组),每组20例.全麻诱导气管插管后,于平卧位(T0)、头高位45.后1.5 min(T1)、3.5 min(T2)、5.5 min(T3)时记录MAP和大脑中动脉血流速度(MBFV).结果 与T0时相比,C组和D组T1,2时MAP,T1时MBFV降低,ANS-D组T1-3时MAP和MBFV降低(P<0.05),各组间比较MAP和MBFV差异无统计学意义(P>0.05).结论 头高位时非糖尿病、无自主神经病变的糖尿病患者和糖尿病并发自主神经病变患者全麻下脑血流速度均降低且无差别.%Objective To investigate the effect of head-up tilt on cerebral blood flow velocity during general anesthesia in patients with diabetic neuropathy.Methods Sixty ASA Ⅰ - Ⅱ patients of both sexes aged 40-60 yr weighing 52-70 kg undergoing general anesthesia were divided into 3 groups according to diseases complicated with diabetes situation ( n =20 each):group Ⅰ normal control the patients did not have diabetes mellitus; group Ⅱ type Ⅱ diabetics without neuropathy and group Ⅲ Ⅱ diabetics with neuropathy.Anesthesia was induced with propofol 2 mg/kg,fentanyl 3 μg/kg and vecuronium 0.1 mg/kg and maintained with 1% sevoflurane.The patients were intubated and mechanically ventilated.PErCO2 was maintained at 35-45 mm Hg.Transcranial doppler (TCD)was used to measure middle cerebral artery blood flow velocity (MBFV).MAP and MBFV were measured and recorded in supine position (baseline) and at 1.5,3.5 and 5.5 min of 45° head-up tilt.Results The 3 groups were comparable with respect to age,body weight,height and M/F sex ratio.MAP and MBFV significantly decreased at 45° head-up tilt as compared with the baseline in all

  10. Motion compensated beamforming in synthetic aperture vector flow imaging

    DEFF Research Database (Denmark)

    Oddershede, Niels; Jensen, Jørgen Arendt

    2006-01-01

    . Here the SNR is -10 dB compared to the stationary scatterer. A 2D motion compensation method for synthetic aperture vector flow imaging is proposed, where the former vector velocity estimate is used for compensating the beamforming of new data. This method is tested on data from an experimental flow......In synthetic aperture imaging the beamformed data from a number of emissions are summed to create dynamic focusing in transmit. This makes the method susceptible to motion, which is especially the case for the synthetic aperture flow estimation method, where large movements are expected......) of the beamformed response from the scatterer at all velocities is compared to that of a stationary scatterer. For lateral movement, the SNR drops almost linearly with velocity to -4 dB at I m/s, while for axial movement the SNR drop is largest, when the scatterer moves a quarter of a wavelength between emissions...

  11. Complex Vector Formalism of Harmonic Oscillator in Geometric Algebra: Particle Mass, Spin and Dynamics in Complex Vector Space

    Science.gov (United States)

    Muralidhar, K.

    2014-03-01

    Elementary particles are considered as local oscillators under the influence of zeropoint fields. Such oscillatory behavior of the particles leads to the deviations in their path of motion. The oscillations of the particle in general may be considered as complex rotations in complex vector space. The local particle harmonic oscillator is analyzed in the complex vector formalism considering the algebra of complex vectors. The particle spin is viewed as zeropoint angular momentum represented by a bivector. It has been shown that the particle spin plays an important role in the kinematical intrinsic or local motion of the particle. From the complex vector formalism of harmonic oscillator, for the first time, a relation between mass and bivector spin has been derived in the form . Where, is the angular velocity bivector of complex rotations, is the velocity of light. The unit vector acts as an operator on the idempotents and to give the eigen values The constant represents two fold nature of the equation corresponding to particle and antiparticle states. Further the above relation shows that the mass of the particle may be interpreted as a local spatial complex rotation in the rest frame. This gives an insight into the nature of fundamental particles. When a particle is observed from an arbitrary frame of reference, it has been shown that the spatial complex rotation dictates the relativistic particle motion. The mathematical structure of complex vectors in space and spacetime is developed.

  12. About the velocity operator for spinning particles in quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Salesi, Giovanni [Universita Statale di Catania (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Catania (Italy); Recami, Erasmo; Rodrigues Junior, Waldyr A. [Universidade Estadual de Campinas, SP (Brazil). Dept. de Matematica Aplicada

    1995-12-01

    Starting from the formal expressions of the hydrodynamical (or local) quantities employed in the applications of Clifford Algebras to quantum mechanics, we introduce - in terms of the ordinary tensorial framework - a new definition for the field of a generic quantity. By translating from Clifford into sensor algebra, we also propose a new (non-relativistic) velocity operator for a spin 1/2 particle. This operator is the sum of the ordinary part p/m describing the mean motion (the motion of the center-of-mass), and of a second part associated with the so-called Zitterbewegung, which is the spin internal motion observed in the center-of-mass frame. This spin component of the velocity operator is non-zero not only in the Pauli theoretical framework in presence of external magnetic fields and spin precession, but also in the Schroedinger case, when the wave-function is a spin eigenstate. In the latter case, one gets a decomposition of the velocity field for the Madelueng fluid into two distinct parts: which constitutes the non-relativistic analogue of the Gordon decomposition for the Dirac current. We find furthermore that the Zitterbewegung motion involves a velocity field which is solenoidal, and that the local angular velocity is parallel to the spin vector. In presence of a non-constant spin vector (Pauli case) we have, besides the component normal to spin present even in the Schroedinger theory, also a component of the local velocity which is parallel to the rotor of the spin vector. (author). 19 refs.

  13. Calculus with vectors

    CERN Document Server

    Treiman, Jay S

    2014-01-01

    Calculus with Vectors grew out of a strong need for a beginning calculus textbook for undergraduates who intend to pursue careers in STEM. fields. The approach introduces vector-valued functions from the start, emphasizing the connections between one-variable and multi-variable calculus. The text includes early vectors and early transcendentals and includes a rigorous but informal approach to vectors. Examples and focused applications are well presented along with an abundance of motivating exercises. All three-dimensional graphs have rotatable versions included as extra source materials and may be freely downloaded and manipulated with Maple Player; a free Maple Player App is available for the iPad on iTunes. The approaches taken to topics such as the derivation of the derivatives of sine and cosine, the approach to limits, and the use of "tables" of integration have been modified from the standards seen in other textbooks in order to maximize the ease with which students may comprehend the material. Additio...

  14. Synthetic Space Vector Modulation

    Science.gov (United States)

    2013-06-01

    Modulation RF Radio Frequency SVM Space Vector Modulation VCO Voltage Controlled Oscillator VSI Voltage Source Inverter xvi THIS PAGE...examining the literature, an NE566 voltage controlled oscillator ( VCO ) chip as seen in Figure 10 was used to design a circuit that produced the

  15. Vectors Point Toward Pisa

    Science.gov (United States)

    Dean, Richard A.

    1971-01-01

    The author shows that the set of all sequences in which each term is the sum of the two previous terms forms a vector space of dimension two. He uses this result to obtain the formula for the Fibonacci sequence and applies the same technique to other linear recursive relations. (MM)

  16. Vector-borne Infections

    Centers for Disease Control (CDC) Podcasts

    2011-04-18

    This podcast discusses emerging vector-borne pathogens, their role as prominent contributors to emerging infectious diseases, how they're spread, and the ineffectiveness of mosquito control methods.  Created: 4/18/2011 by National Center for Emerging Zoonotic and Infectious Diseases (NCEZID).   Date Released: 4/27/2011.

  17. Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR

    Science.gov (United States)

    Osborn, J.; Butterley, T.; Townson, M. J.; Reeves, A. P.; Morris, T. J.; Wilson, R. W.

    2017-02-01

    As telescopes become larger, into the era of ˜40 m Extremely Large Telescopes, the high-resolution vertical profile of the optical turbulence strength is critical for the validation, optimization and operation of optical systems. The velocity of atmospheric optical turbulence is an important parameter for several applications including astronomical adaptive optics systems. Here, we compare the vertical profile of the velocity of the atmospheric wind above La Palma by means of a comparison of Stereo-SCIntillation Detection And Ranging (Stereo-SCIDAR) with the Global Forecast System models and nearby balloon-borne radiosondes. We use these data to validate the automated optical turbulence velocity identification from the Stereo-SCIDAR instrument mounted on the 2.5 m Isaac Newton Telescope, La Palma. By comparing these data we infer that the turbulence velocity and the wind velocity are consistent and that the automated turbulence velocity identification of the Stereo-SCIDAR is precise. The turbulence velocities can be used to increase the sensitivity of the turbulence strength profiles, as weaker turbulence that may be misinterpreted as noise can be detected with a velocity vector. The turbulence velocities can also be used to increase the altitude resolution of a detected layer, as the altitude of the velocity vectors can be identified to a greater precision than the native resolution of the system. We also show examples of complex velocity structure within a turbulent layer caused by wind shear at the interface of atmospheric zones.

  18. Exceptional Ground Accelerations and Velocities Caused by Earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, John

    2008-01-17

    This project aims to understand the characteristics of the free-field strong-motion records that have yielded the 100 largest peak accelerations and the 100 largest peak velocities recorded to date. The peak is defined as the maximum magnitude of the acceleration or velocity vector during the strong shaking. This compilation includes 35 records with peak acceleration greater than gravity, and 41 records with peak velocities greater than 100 cm/s. The results represent an estimated 150,000 instrument-years of strong-motion recordings. The mean horizontal acceleration or velocity, as used for the NGA ground motion models, is typically 0.76 times the magnitude of this vector peak. Accelerations in the top 100 come from earthquakes as small as magnitude 5, while velocities in the top 100 all come from earthquakes with magnitude 6 or larger. Records are dominated by crustal earthquakes with thrust, oblique-thrust, or strike-slip mechanisms. Normal faulting mechanisms in crustal earthquakes constitute under 5% of the records in the databases searched, and an even smaller percentage of the exceptional records. All NEHRP site categories have contributed exceptional records, in proportions similar to the extent that they are represented in the larger database.

  19. Velocity centroids as tracers of the turbulent velocity statistics

    CERN Document Server

    Lazarian, A E A

    2004-01-01

    We use the results of magnetohydrodynamic (MHD) simulations to emulate spectroscopic observations, and produce maps of variations of velocity centroids to study their scaling properties. We compare them with those of the underlying velocity field, and analytic predictions presented in a previous paper (Lazarian & Esquivel 2003). We tested, with success, a criteria for recovering velocity statistics from velocity centroids derived in our previous work. That is, if >> (where S is a 2D map of ``unnormalized'', v velocity, and I integrated intensity map -column density-), then the structure function of the centroids is dominated by the structure function of velocity. We show that it is possible to extract the velocity statistics using centroids for subsonic and mildly supersonic turbulence (e.g. Mach numbers ~2.5). While, towards higher Mach numbers other effects could affect significantly the statistics of centroids.

  20. Statistics of Velocity from Spectral Data Modified Velocity Centroids

    CERN Document Server

    Lazarian, A

    2003-01-01

    We address the problem of studying interstellar (ISM) turbulence using spectral line data. We construct a measure that we term modified velocity centroids (MVCs) and derive an analytical solution that relates the 2D spectra of the modified centroids with the underlying 3D velocity spectrum. We test our results using synthetic maps constructed with data obtained through simulations of compressible MHD turbulence. We prove that the MVCs are able to restore the underlying spectrum of turbulent velocity. We show that the modified velocity centroids (MVCs) are complementary to the the Velocity Channel Analysis (VCA) technique that we introduced earlier. Employed together they make determining of the velocity spectral index more reliable. At the same time we show that MVCs allow to determine velocity spectra when the underlying statistics is not a power law and/or the turbulence is subsonic.