Ow Measurements Research Articles

Normal Echocardiographic Measurements in Uncomplicated Pregnancy, a Single Center Experience

Background: Cardiovascular changes of pregnancy are well-known; however, parameters for accurately assessing these changes have not been refined as measurement tools have advanced. We sought to examine the range of echocardiographic parameters during normal pregnancy using current echocardiographic imaging modalities. Methods: We performed a retrospective analysis of normal echocardiograms in 121 women (97 pregnant, 24 non-pregnant) without evidence of cardiovascular disease. Linear, area, and Doppler fl ow measurements were made of commonly reviewed cardiac structures. Height-indexed measurements were compared between pregnant women and controls and between trimesters of pregnancy. Results: Compared to non-pregnant patients, all four cardiac chambers showed significant enlargement in the pregnant patients. The left atrium was the first chamber to enlarge. LV mass also increased in the third trimester (134.5 ± 31 vs. 112.3 ± 28.2 g, P & lt; 0.01), with preservation of LV mass to volume ratio. LV ejection fraction was significantly larger (68% vs. 63%, P Conclusion: This study provides data on echocardiographic parameters during normal pregnancy and is one of the largest sample sizes in the literature. The results will contribute to the current literature by helping to distinguish between normal and abnormal echocardiograms during pregnancy. Key words: Chamber quantifi cations, echocardiography, pregnancy.

The Application of Ultrasonic Methods to Flow Measurement and Detection of Microembolus in Heart Prostheses

and Detection of Microembolus in Heart Prostheses M. Gawlikowskia,∗, M. Lewandowski, A. Nowicki, R. Kustosz, M. Walczak, P. Karwat and P. Karaowicz Foundation of Cardiac Surgery Development, Wolno±ci 345a, 41-800 Zabrze, Poland Institute of Fundamental Technological Researches, PAS, Pawi«skiego 5B, 02-106 Warsaw, Poland Sonomed Ltd., Pruszkowska 4d, 02-118 Warsaw, Poland For the last 20 years the world cardiosurgery has presented a considerable change of attitude to mechanical circulatory support. In spite of technological progress the main problems in ventricular assist devices are: thrombosis and low accuracy of ow measurements. In this paper the prototype of multi-gate Doppler owmeter intended for cardiac assist system ReligaHeart EXT has been presented as well as the possibility of ultrasonic microembolus detection. DOI: 10.12693/APhysPolA.124.417

On the use of colour in experimental fluid mechanics

This paper discusses how colour is used in experimental fl uid fl ow studies. Firstly, colour (defi ned scientifi cally by the wavelength of the light) can be used to discriminate between different channels in optical instrumentation, making it possible to measure several fl ow properties, simultaneously, and without any intrusion into the fl ow. These aspects of modern fl ow measurement are discussed in terms of some examples. Alternatively, the results of the fl ow measurement may be represented in the form of images, graphs and three-dimensional schematics with colour being used to identify and emphasise particular features that might otherwise remain concealed. The experimental results presented in the paper confi rm that using colour to discriminate between sets of data has several important advantages over the older black and white or grey scale forms of representation. Not only do colours provide an excellent basis for communication through graphical and three-dimensional presentations, but the resulting clarity may also help to reveal complex forms of flfl ow behaviour. Moreover, the inherent artistic appeal of some colour representations can draw the viewer into the technical detail, helping to simplify physical phenomena in ways that would not otherwise be possible. Although the observations made on the presentation of data are illustrated with reference to a number of experimental fl uid fl ow problems, many of the methods and observations would be applicable in other situations, where scientifi c or technological data needs to be presented.

Toasting the jelly sandwich: The effect of shear heating on lithospheric geotherms and strength

We refi ne conventional continental-scale geodynamic models by including conversion of mechanical work done by deformation into heat. The intensity of the shear heating is extracted from the BraceGoetze strength envelope without any additional model parameters or assumptions. Incorporation of this, certainly present, heating rate into a model may result in up to tenfold stress reduction, which is exceeding the effects of variation of common parameters within their uncertainty limits. Shear heating with lithospheric thickening at high integrated strength solves the puzzle of the heretofore-missing heat source recorded by metamorphism, magmatism, and heat fl ow in mountain building. However, the mechanism is self-limiting as the rising temperature reduces stress and thus the rate of heat production. Thus this is a self-regulating mechanism maintaining a moderate integrated lithospheric strength consistent with results of model-independent forcebalanced calculations and with surface heat fl ow measurements.

Helmholtz-Like Resonator Self-Sustained Oscillations, Part 2: Detailed Flow Measurements and Numerical Simulations

A global description of the effect of the neck geometry on self-sustained oscillations of a grazing e ow along a Helmholtz-like resonator has been given in a companion paper. Detailed e ow measurements taken by means of hot-wire anemometry and numerical simulations based on the Euler equations for inviscid and two-dimensional compressible e ows are now given. Vortex shedding is obtained in an inviscid e ow simulation by considering a neck geometry with sharp edgesat which the code predictse ow separation. Although two-dimensional e owcalculations are attractive because of their computational efe ciency, they are not able to represent the three-dimensional acoustical radiation from the resonator into free space without special frequency-dependent boundary condition treatments. Frequency-independent time-domain boundary conditions are considered. In view of the crudeness of this approximation, the agreement between theory and experiments is quite fair. The effects of changes in the geometry of theneck are qualitatively predicted by the model. The detailed e owinformation provides someinsight into the ine uence of the shape of the upstream edge of the neck that could not be obtained from analytical models proposed in the companion paper.

Method for measuring the logarithm of the octanol–water partition coefficient by using short octadecyl–poly(vinyl alcohol) high-performance liquid chromatography columns

A simple, quick, versatile and inexpensive HPLC method to estimate the logarithm of the octanol–water partition coefficient (log P ow) employing a methanol–water gradient and a short octadecyl–poly(vinyl alcohol) (ODP) column is described. This method is different from published HPLC-based log P ow methods because it uses retention times from a rapid methanol–water gradient to directly generate log P ow estimates, rather than from a series of isocratic mixtures extrapolated to 100% water. These HPLC log P ow values have good precision and correlate well with traditional shake-flask log P ow values. If necessary, the log P ow determination (including replications) can easily be carried out using only a milligram of sample. By suppressing ionization of acids and bases by the use of a buffer in the aqueous phase, the method can measure the log P ow of neutral organic molecules at any pH between 2 and 13. The method can be used with impure material and is rapid, 7 min per run and 4 min equilibration; it lends itself to and has been utilized for high-throughput hydrophobicity determinations (we have now carried out thousands of HPLC log P ow measurements by this method).

Flow Properties of a Supersonic Turbulent Boundary Layer with Wall Roughness

Anexperimental study ofthe ine uenceofsurfaceroughness on themean and turbulente owproperties of a highspeed (M =2:9;Re/m=2:0 ££ 10 7 ) turbulent boundary layer e ow was performed. Six wall topologies, including a smooth and e ve rough surfaces consisting of three random sand-grain plates and two uniformly machined plates (k + =100‐570), were tested. Mean e ow measurements included surveys of the velocity and density. Turbulence quantities included direct measurements of the kinematic velocity turbulence intensities, mass e ux turbulence intensities, thekinematicReynoldsshearstress,thecompressibleReynoldsshearstressandthedensity-transversevelocity e uctuation correlation. The trends in the mean e ow, observed for incompressible e ow, were found to hold forthepresentstudywhenVanDriestIIscalingwasused.Kinematicstatisticalturbulente owpropertieswerefound to scale by local mean quantities. Conversely, turbulent e ow statistical properties with an explicit thermodynamic dependence did not scale by local mean quantities and had a strong linear dependence on roughness height. Roughnesswasfound to extend theregion where inner scaling held toward larger values of y + for thecompressible Reynolds shear stress, the x- and y-velocity component turbulence intensities, the x-component of the mass e ux turbulence intensity, and the density-transverse-velocity correlation.

Two-Dimensional Nonadiabatic Injection into a Supersonic Freestream

Turbulence and mean e ow measurements were acquired downstream of a normal, supersonic (Mach 1.6), twodimensional, slot injection into Mach 2.9 e ow (Re/m=16 £ 10 6).An adiabatic (Tti/Tt1 =1.0)and two nonadiabatic injection cases (Tti/Tt1 =1.11andTti/Tt1 =0.93)werestudied.Multiple-overheatcross-e lmanemometryandconventional mean e ow probes, as well as instantaneous schlieren photography, were utilized to study the turbulent mixing layer. The mean e ow data included the pitot, cone-static, and Mach number proe les. The measured turbulence data included Reynolds shear stresses and turbulence intensities (mass e ux and total temperature ). The e ow visualizations highlighted the physical phenomena of the e ow as well as the associated turbulent structure that existed in the mixing layer. The injection and wall temperature were found to have a strong ine uence on the near wall (the bottom-half of the mixing layer relative to the wall ) mean and statistical turbulent e ow properties.

Development of a Nearly Omnidirectional Velocity Measurement Pressure Probe

The development of a nearly omnidirectional pressure probe for three-velocity-component and pressure measurements is described, focusing on the techniques employed in probe fabrication, calibration, and frequencyresponse study. The probe tip is a sphere with 18 pressure ports properly distributed over the spherical surface. The device eliminates the velocity directionality limitations of current multihole probes and constitutes a rugged tool for use in complex three-dimensional e ow mapping. An automated calibration system was used to generate a probe calibration database of approximately 10,000 individual probe orientations. Least-squares-based and neural-network-based calibration algorithms were developed. The reliability of the calibration procedures and algorithms is demonstrated e rst. Then probe utility is demonstrated in a e owe eld with e ow reversal, downstream of a backward-facing step. Last, a study of the probe frequency response is presented. I. Introduction T HE design, evaluation, and optimization of complex aerodynamicgeometriesinvolveextensivewind-tunneltestingand/or computationally intensive numerical simulations. Even in the latter case, high-quality experimental wind-tunnel results with minimal, quantie able errors are still necessary for code-validation purposes. Moreover, in aerodynamic testing facilities where large volumes of data need to be acquired in tight schedules, downtime due to poor instrumentation performance is highly undesirable. Such facilities include industrial testing wind tunnels, as well as high-productivity computational e uid dynamics code validation facilities. 1 In such environments, e ow measurement techniques such as laser Doppler velocimetry and particle image velocimetry, although powerful, usually require painstaking efforts toward their successful usage. Costly components; complex setups; troublesome e ow seeding requirements; lack of e exibility, ruggedness, and mobility; and ease of misalignment often render such techniques impractical. Moreover, in testing of complex three-dimensional geometries, accessibility of the entire e owe eld around the model is an essential issue. When employing optical techniques, large sections of the e owe eld are obstructed optically by the presence of the model. To access such regions, repositioning of the instrumentation setup is necessary, a time-consuming process with the associated potential pitfalls. Multihole pressure probes 2‐7 in many cases have provided the easiest-to-use and most cost-effective method for three-component e ow velocity measurements in research and industry environments. However, even with expanded measurement capabilities of such instruments, the current pressure probe cone gurations and techniques have a limited range of velocity inclinations that they can measure. The velocity inclination is indicated as the cone angle µ in Fig. 1. Let µmax be the maximum cone angle that can be measured reliably by the probe. In other words, a probe with a µmax of 40 deg can accurately measure any velocity vector that is contained within a cone with its apex at the probe tip, its axis along the probe axis, and with an apex included angle of 80 deg (Fig. 1). Measurable cone angles as high as 75 deg are not uncommon for seven-hole probes. 7 Following this reasoning, an omnidirectional probe is a probe that has a cone angle of 180 deg (360 deg included angle ); i.e., it can measure any velocity vector regardless of its orientation. The present work describes the development of a nearly omnidirectional probe that can measure up to cone angles of 170 deg