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Sample records for ventricular blood vorticity

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

    Science.gov (United States)

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

    2013-01-01

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

  2. Doppler vortography: a color Doppler approach to quantification of intraventricular blood flow vortices.

    Science.gov (United States)

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

    2014-01-01

    We propose a new approach to quantification of intracardiac vorticity based on conventional color Doppler images -Doppler vortography. Doppler vortography relies on the centrosymmetric properties of the vortices. Such properties induce particular symmetries in the Doppler flow data that can be exploited to describe the vortices quantitatively. For this purpose, a kernel filter was developed to derive a parameter, the blood vortex signature (BVS), that allows detection of the main intracardiac vortices and estimation of their core vorticities. The reliability of Doppler vortography was assessed in mock Doppler fields issued from simulations and in vitro data. Doppler vortography was also tested in patients and compared with vector flow mapping by echocardiography. Strong correlations were obtained between Doppler vortography-derived and ground-truth vorticities (in silico: r2 = 0.98, in vitro: r2 = 0.86, in vivo: r2 = 0.89). Our results indicate that Doppler vortography is a potentially promising echocardiographic tool for quantification of vortex flow in the left ventricle. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  3. Fluid vortices

    National Research Council Canada - National Science Library

    Green, Sheldon I

    1995-01-01

    ... . . . . . . . . . . . . . . . Vorticity Kinematics and Dynamics - Physical Principles The Vorticity Equation with Examples . . . . Summary . . . . . . . . . . . . . . . . . Vorticity in Orthogonal...

  4. Left ventricular dysfunction and blood glycohemoglobin levels in young diabetics

    Energy Technology Data Exchange (ETDEWEB)

    Aydiner, A.; Oto, A.; Oram, E.; Oram, A.; Ugurlu, S.; Karamehmetoglu, A. (Hacettepe Univ., Ankara (Turkey). Dept. of Cardiology); Aras, T.; Bekdik, C.F. (Hacettepe Univ., Ankara (Turkey). Dept. of Nuclear Medicine); Gedik, O. (Hacettepe Univ., Ankara (Turkey). Dept. of Endocrinology)

    1991-10-01

    Left ventricular function including regional wall motion (RWM) was evaluated by {sup 99m}Tc first-pass and equilibrium gated blood pool ventriculography and glycohemoglobin (HbA1c) blood levels determined by a quantitative column technique in 25 young patients with insulin-dependent diabetes mellitus without clinical evidence of heart diesease, and in healthy controls matched for age and sex. Phase analysis revealed abnormal RWM in 19 of 21 diabetic patients. The mean left ventricular global ejection fraction, the mean regional ejection fraction and the mean 1/3 filling fraction were lower and the time to peak ejection, the time to peak filling and the time to peak ejection/cardiac cycle were longer in diabetics than in controls. We found high HbA1c levels in all diabetics. There was no significant difference between patients with and without retinopathy and with and without peripheral neuropathy in terms of left ventricular function and HbA1c levels. (orig.).

  5. Relationship of central and peripheral blood pressure to left ventricular mass in hypertensive patients.

    Science.gov (United States)

    Pérez-Lahiguera, Francisco J; Rodilla, Enrique; Costa, Jose A; Gonzalez, Carmen; Martín, Joaquin; Pascual, Jose M

    2012-12-01

    The purpose of the present study was to assess the relationship of central and peripheral blood pressure to left ventricular mass. Cross-sectional study that included 392 never treated hypertensive individuals. Measurement of office, 24-h ambulatory, and central blood pressure (obtained using applanation tonometry) and determination of left ventricular mass by echocardiography were performed in all patients. In a multiple regression analysis, with adjustment for age, gender and metabolic syndrome, 24-h blood pressure was more closely related to ventricular mass than the respective office and central blood pressures. Systolic blood pressures always exhibited a higher correlation than diastolic blood pressures in all 3 determinations. The correlation between left ventricular mass index and 24-h systolic blood pressure was higher than that of office (P<.002) or central systolic blood pressures (P<.002). Changes in 24-h systolic blood pressure caused the greatest variations in left ventricular mass index (P<.001). In our population of untreated middle-aged hypertensive patients, left ventricular mass index is more closely related to 24-h ambulatory blood pressure than to office or central blood pressure. Central blood pressure does not enable us to better identify patients with left ventricular hypertrophy. Copyright © 2012 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

  6. Exercise capacity and blood pressure associations with left ventricular mass in prehypertensive individuals.

    Science.gov (United States)

    Kokkinos, Peter; Pittaras, Andreas; Narayan, Puneet; Faselis, Charles; Singh, Steven; Manolis, Athanasios

    2007-01-01

    Prehypertensive individuals are at increased risk for developing hypertension and cardiovascular disease compared with those with normal blood pressure. Early compromises in left ventricular structure may explain part of the increased risk. We assessed echocardiographic and exercise parameters in prehypertensive individuals (n=790) to determine associations between exercise blood pressure and left ventricular structure. The exercise systolic blood pressure at 5 metabolic equivalents (METs) and the change in blood pressure from rest to 5 METs were the strongest predictors of left ventricular hypertrophy. We identified the systolic blood pressure of 150 mm Hg at the exercise levels of 5 METs as the threshold for left ventricular hypertrophy. There was a 4-fold increase in the likelihood for left ventricular hypertrophy for every 10-mm Hg increment in systolic blood pressure beyond this threshold (OR: 1.15; 95% CI: 1.12 to 1.18). There was also a 42% reduction in the risk for left ventricular hypertrophy for every 1 MET increase in the workload (OR: 0.58; Pfit, moderate, and high-fit individuals exhibited significantly lower systolic blood pressure at an exercise workload of 5 METs (155+/-14 versus 146+/-10 versus 144+/-10; Phypertrophy (48.3% versus 18.7% versus 21.6%; Pfitness achieved by moderate intensity physical activity can improve hemodynamics and cardiac performance in prehypertensive individuals and reduce the work of the left ventricle, ultimately resulting in lower left ventricular mass.

  7. Optimized Time-Resolved Echo PIV-PTV Measurements Elucidate Blood Flow in Patients with Left Ventricular Thrombus.

    Science.gov (United States)

    Sampath, Kaushik; Harfi, Thura T; George, Ricard/T; Katz, Joseph

    2018-01-05

    Contrast ultrasound is a widely used clinical tool to obtain real-time qualitative blood flow assessments in the heart, liver, etc. Echocardiographic particle image velocimetry (echo-PIV) is a technique for obtaining quantitative velocity maps from contrast ultrasound images. However, unlike optical PIV, routine echo images are prone to non-uniform spatiotemporal variations in tracer distribution, making analysis difficult for standard PIV algorithms. This study introduces optimized procedures that integrate image enhancement, PIV and particle tracking velocimetry (PTV) to obtain reliable time-resolved 2D velocity distributions. During initial PIV analysis, multiple results are obtained by varying processing parameters. Optimization involving outlier removal and smoothing is used to select the correct vector. These results are used in a multi-parameter PTV procedure. To demonstrate their clinical value, the procedures are implemented to obtain velocity and vorticity distributions over multiple cardiac cycles using images acquired from four left ventricular thrombus (LVT) patients. Phase averaged data elucidate flow structure evolution over the cycle and are used to calculate penetration depth and strength of LV vortices, as well as apical velocity induced by them. Present data are consistent with existing[1] time-averaged minimum vortex penetration associated with LVT occurrence. However, due to decay and fragmentation of LV vortices, as they migrate away from the mitral annulus, in two cases with high penetration, there is still poor washing near the resolved clot throughout the cycle. Hence, direct examination of entire flow evolution may be useful for assessing risk of LVT relapse before prescribing anticoagulants.

  8. Right ventricular function in patients with mitral valve disease; Evaluation by radionuclide blood pool scan

    Energy Technology Data Exchange (ETDEWEB)

    Hiraki, Yoshio; Shimizu, Mitsuharu; Noriyasu, Toshiaki; Nakagawa, Tomio; Aono, Kaname; Yanagi, Hidekiyo; Seno, Yoshimasa; Teramoto, Shigeru; Nagaya, Isao (Okayama Univ. (Japan). School of Medicine)

    1989-10-01

    Right ventricular function was studied in 13 patients with mitral valve stenosis (MS), 10 patients with mitral valve regurgitation (MR) and 10 patients after mitral valve replacement (MVR) with radionuclide blood pool scan. In MS, right ventricular end-diastolic and end-systolic volumes were larger than MVR. In MR, right ventricular ejection fraction (RVEF) was smaller and right ventricular end-systolic volume was larger than MVR. In both MS and MR, there was no significant linear correlation between RVEF and mean pulmonary arterial pressure (mPAP) at rest, but during exercise RVEF of patients with elevated mPAP decreased more than that of patients with normal mPAP. RVEF in patients with MS and MR was significantly decreased during exercise, while that in patients after MVR showed no significant change. Radionuclide blood pool scan seems to be useful for the evaluation of right ventricular function in mitral valve disease. (author).

  9. Home blood pressure measurement : reproducibility and relationship with left ventricular mass

    NARCIS (Netherlands)

    Kok, R.H.; Beltman, F.W.; Terpstra, W.F.; Smit, A.J.; May, J.F.; de Graeff, P.A.; Meyboom-de Jong, B.

    1999-01-01

    OBJECTIVE: To evaluate the reproducibility and relationship with left ventricular mass index of home blood pressure in comparison with ambulatory and office blood pressures. METHODS: We measured home, ambulatory and office blood pressures of 84 previously untreated hypertensive patients, aged 60-74

  10. Vortical flows

    CERN Document Server

    Wu, Jie-Zhi; Zhou, Ming-De

    2015-01-01

    This book is a comprehensive and intensive book for graduate students in fluid dynamics as well as scientists, engineers and applied mathematicians. Offering a systematic introduction to the physical theory of vortical flows at graduate level, it considers the theory of vortical flows as a branch of fluid dynamics focusing on shearing process in fluid motion, measured by vorticity. It studies vortical flows according to their natural evolution stages,from being generated to dissipated. As preparation, the first three chapters of the book provide background knowledge for entering vortical flows. The rest of the book deals with vortices and vortical flows, following their natural evolution stages. Of various vortices the primary form is layer-like vortices or shear layers, and secondary but stronger form is axial vortices mainly formed by the rolling up of shear layers.  Problems are given at the end of each chapter and Appendix, some for helping understanding the basic theories, and some involving specific ap...

  11. Comparison of Blood Lipids, Blood Pressures and Left Ventricular Cavity Dimension between Soccer Players and Non-Athletes

    Science.gov (United States)

    Gokhan, Ismail; Kurkcu, Recep; Cekin, Resul

    2013-01-01

    In this study, it was aimed to compare the investigate the effects of regular exercise on blood lipids, blood pressure and left ventricular cavity dimensions function between soccer players and non-athletes in football players. This study consisted included a total of 30 subjects, including an experimental group including 18 soccer players…

  12. Noninvasive arterial blood pressure waveforms in patients with continuous-flow left ventricular assist devices

    NARCIS (Netherlands)

    Martina, Jerson R.; Westerhof, Berend E.; de Jonge, Nicolaas; van Goudoever, Jeroen; Westers, Paul; Chamuleau, Steven; van Dijk, Diederik; Rodermans, Ben F. M.; de Mol, Bas A. J. M.; Lahpor, Jaap R.

    2014-01-01

    Arterial blood pressure and echocardiography may provide useful physiological information regarding cardiac support in patients with continuous-flow left ventricular assist devices (cf-LVADs). We investigated the accuracy and characteristics of noninvasive blood pressure during cf-LVAD support.

  13. Gated blood-pool SPECT automated versus manual left ventricular function calculations

    NARCIS (Netherlands)

    Slart, RHJA; Poot, L; Piers, DA; van Veldhuisen, DJ; Nichols, K; Jager, PL

    Planar gated blood-pool imaging (GBPI) is a standard method for non-invasive assessment of left ventricular (LV) function. Gated blood-pool single photon emission computed tomographic (GBPS) data acquisition can be accomplished in the same time as GBPI, with the benefit of enabling visualization of

  14. Frequent left ventricular hypertrophy independent of blood pressure in 1851 pre-western Inuit

    DEFF Research Database (Denmark)

    Andersen, Stig; Kjærgaard, Marie; Jørgensen, Marit Eika

    2011-01-01

    BACKGROUND: Elevated blood pressure is a risk factor for cardiovascular disease and may be detected by left ventricular hypertrophy (LVH) in electrocardiogram (ECG). Pre-western Inuit had frequent signs of LVH in ECG predominantly in the 3rd decade while a low occurrence of ischemic heart disease....... METHODS: We evaluated the association between blood pressures and ECG signs of LVH, cardiac auscultation, and symptoms related to heart disease in the recently recovered data from the survey of 1851 Inuit conducted in 1962-1964 in East Greenland. RESULTS: The participation rate was 97%. Among the 812...... only after the age of 40 years in pre-western Inuit. Left ventricular hypertrophy peaked among 30-year olds and was independent of elevated blood pressure. It may be speculated that the common left ventricular hypertrophy was due to marked physical activity that contributed to the low occurrence...

  15. Dynamic modeling of uteroplacental blood flow in IUGR indicates vortices and elevated pressure in the intervillous space - a pilot study

    Science.gov (United States)

    Roth, Christian J.; Haeussner, Eva; Ruebelmann, Tanja; Koch, Franz V.; Schmitz, Christoph; Frank, Hans-Georg; Wall, Wolfgang A.

    2017-01-01

    Ischemic placental disease is a concept that links intrauterine growth retardation (IUGR) and preeclampsia (PE) back to insufficient remodeling of uterine spiral arteries. The rheological consequences of insufficient remodeling of uterine spiral arteries were hypothesized to mediate the considerably later manifestation of obstetric disease. However, the micro-rheology in the intervillous space (IVS) cannot be examined clinically and rheological animal models of the human IVS do not exist. Thus, an in silico approach was implemented to provide in vivo inaccessible data. The morphology of a spiral artery and the inflow region of the IVS were three-dimensionally reconstructed to provide a morphological stage for the simulations. Advanced high-end supercomputing resources were used to provide blood flow simulations at high spatial resolution. Our simulations revealed turbulent blood flow (high-velocity jets and vortices) combined with elevated blood pressure in the IVS and increased wall shear stress at the villous surface in conjunction with insufficient spiral artery remodeling only. Post-hoc histological analysis of uterine veins showed evidence of increased trophoblast shedding in an IUGR placenta. Our data support that rheological alteration in the IVS is a relevant mechanism linking ischemic placental disease to altered structural integrity and function of the placenta.

  16. Blood pressure control and left ventricular hypertrophy in ...

    African Journals Online (AJOL)

    Medicine, Federal Medical Centre, PMB 3031 Sapon, Abeokuta, Ogun State, Nigeria, 2Department of Accident and. Emergency, University ... Conclusion: Clinic blood pressure is an ineffective way of assessing BP control. Thus in apparently ..... Relationship between the level, pattern and variability of ambulatory blood.

  17. Left ventricular performance, regional blood flow, wall motion, and lactate metabolism during transluminal angioplasty

    NARCIS (Netherlands)

    P.W.J.C. Serruys (Patrick); W. Wijns (William); M.J.B.M. van den Brand (Marcel); S. Meij (Simon); J.C.H. Schuurbiers (Johan); P.W. Hugenholtz; R.W. Brower (Ronald); C.J. Slager (Cornelis)

    1984-01-01

    textabstractThe response of left ventricular function, coronary blood flow, and myocardial lactate metabolism during percutaneous transluminal coronary angioplasty (PTCA) was studied in a series of patients undergoing the procedure. From four to six balloon inflation procedures per patient were

  18. Calcium Signaling Regulates Ventricular Hypertrophy During Development Independent of Contraction or Blood Flow

    Science.gov (United States)

    Andersen, Nicholas D.; Ramachandran, Kapil V.; Bao, Michelle M.; Kirby, Margaret L.; Pitt, Geoffrey S.; Hutson, Mary R.

    2014-01-01

    In utero interventions aimed at restoring left ventricular hemodynamic forces in fetuses with prenatally diagnosed hypoplastic left heart syndrome failed to stimulate ventricular myocardial growth during gestation, suggesting chamber growth during development may not rely upon fluid forces. We therefore hypothesized that ventricular hypertrophy during development may depend upon fundamental Ca2+-dependent growth pathways that function independent of hemodynamic forces. To test this hypothesis, zebrafish embryos were treated with inhibitors or activators of Ca2+ signaling in the presence or absence of contraction during the period of chamber development. Abolishment of contractile function alone in the setting of preserved Ca2+ signaling did not impair ventricular hypertrophy. In contrast, inhibition of L-type voltage-gated Ca2+ influx abolished contraction and led to reduced ventricular hypertrophy, whereas increasing L-type voltage-gated Ca2+ influx led to enhanced ventricular hypertrophy in either the presence or absence of contraction. Similarly, inhibition of the downstream Ca2+-sensitive phosphatase calcineurin, a known regulator of adult cardiac hypertrophy, led to reduced ventricular hypertrophy in the presence or absence of contraction, whereas hypertrophy was rescued in the absence of L-type voltage-gated Ca2+ influx and contraction by expression of a constitutively active calcineurin. These data suggest ventricular cardiomyocyte hypertrophy during chamber formation is dependent upon Ca2+ signaling pathways that are unaffected by heart function or hemodynamic forces. Disruption of Ca2+-dependent hypertrophy during heart development may therefore represent one mechanism for impaired chamber formation that is not related to impaired blood flow. PMID:25536179

  19. Endothelial and non-endothelial coronary blood flow reserve and left ventricular dysfunction in systemic hypertension

    Directory of Open Access Journals (Sweden)

    Aloísio Marchi Rocha

    2009-04-01

    Full Text Available OBJECTIVES: We evaluated the impairment of endothelium-dependent and endothelium-independent coronary blood flow reserve after administration of intracoronary acetylcholine and adenosine, and its association with hypertensive cardiac disease. INTRODUCTION: Coronary blood flow reserve reduction has been proposed as a mechanism for the progression of compensated left ventricular hypertrophy to ventricular dysfunction. METHODS: Eighteen hypertensive patients with normal epicardial coronary arteries on angiography were divided into two groups according to left ventricular fractional shortening (FS. Group 1 (FS >0.25: n=8, FS=0.29 ± 0.03; Group 2 (FS <0.25: n=10, FS= 0.17 ± 0.03. RESULTS: Baseline coronary blood flow was similar in both groups (Group 1: 80.15 ± 26.41 mL/min, Group 2: 100.09 ± 21.51 mL/min, p=NS. In response to adenosine, coronary blood flow increased to 265.1 ± 100.2 mL/min in Group 1 and to 300.8 ± 113.6 mL/min (p <0.05 in Group 2. Endothelium-independent coronary blood flow reserve was similar in both groups (Group 1: 3.31 ± 0.68 and Group 2: 2.97 ± 0.80, p=NS. In response to acetylcholine, coronary blood flow increased to 156.08 ± 36.79 mL/min in Group 1 and to 177.8 ± 83.6 mL/min in Group 2 (p <0.05. Endothelium-dependent coronary blood flow reserve was similar in the two groups (Group 1: 2.08 ± 0.74 and group Group 2: 1.76 ± 0.61, p=NS. Peak acetylcholine/peak adenosine coronary blood flow response (Group 1: 0.65 ± 0.27 and Group 2: 0.60 ± 0.17 and minimal coronary vascular resistance (Group 1: 0.48 ± 0.21 mmHg/mL/min and Group 2: 0.34 ± 0.12 mmHg/mL/min were similar in both groups (p= NS. Casual diastolic blood pressure and end-systolic left ventricular stress were independently associated with FS. CONCLUSIONS: In our hypertensive patients, endothelium-dependent and endothelium-independent coronary blood flow reserve vasodilator administrations had similar effects in patients with either normal or decreased left

  20. Assessment of cardiac blood pool imaging in patients with left ventricular outflow tract stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yutaka (Tajimi City Hospital, Gifu (Japan)); Ono, Yasuo; Kohata, Tohru; Tsubata, Shinichi; Kamiya, Tetsuroh

    1993-09-01

    We performed cardiac blood pool imagings with Tc-99m at rest and during supine ergometer exercise to evaluate left ventricular performance in 14 patients with left ventricular outflow tract stenosis. All catheterized patients were divided into two subgroups: 8 patients with peak systolic left ventricular to descending aortic pressure gradients of less than 50 mmHg (LPG group) and 6 patients with peak systolic gradients of more than 50 mmHg (HPG group). Control group included 10 patients without stenotic coronary lesions after Kawasaki disease. Left ventricular ejection fraction (LVEF) was obtained as systolic index; both filling fraction during the first third of diastole (1/3FF) and mean filling rate during the first third of diastole (1/3FR mean) were obtained as diastolic indices. None of the patients had abnormal findings on [sup 201]Tl imaging. LVEF at rest in HPG group was significantly higher than those in control group, but LVEF in HPG group did not increase after exercise. It increased significantly in control group and LPG group. 1/3 FF in HPG group was significantly lower not only at rest but also during exercise. 1/3 FR mean at rest was not different significantly among the 3 groups. However, 1/3FR mean during exercise in LPG group was significantly lower; and 1/3 FR mean during exercise was significantly lower in HPG group than LPG group. The ratio of left ventricular muscular mass to left ventricular end-diastolic volume (M/V) calculated from left ventricular cineangiograms was different significantly among the 3 groups. The M/V ratio showed a correlation with LVEF and 1/3 FF both at rest and during exercise. These results would indicate that systolic function was impaired on exercise in severe left ventricular outflow tract stenosis and diastolic function was impaired on exercise in mild and severe left ventricular outflow tract stenosis. This may correlate with left ventricular hypertrophy and interaction of systolic function. (author).

  1. Right Ventricular Hemodynamics in Patients with Pulmonary Hypertension

    Science.gov (United States)

    Browning, James; Fenster, Brett; Hertzberg, Jean; Schroeder, Joyce

    2012-11-01

    Recent advances in cardiac magnetic resonance imaging (CMR) have allowed for characterization of blood flow in the right ventricle (RV), including calculation of vorticity and circulation, and qualitative visual assessment of coherent flow patterns. In this study, we investigate qualitative and quantitative differences in right ventricular hemodynamics between subjects with pulmonary hypertension (PH) and normal controls. Fifteen (15) PH subjects and 10 age-matched controls underwent same day 3D time resolved CMR and echocardiography. Echocardiography was used to determine right ventricular diastolic function as well as pulmonary artery systolic pressure (PASP). Velocity vectors, vorticity vectors, and streamlines in the RV were visualized in Paraview and total RV Early (E) and Atrial (A) wave diastolic vorticity was quantified. Visualizations of blood flow in the RV are presented for PH and normal subjects. The hypothesis that PH subjects exhibit different RV vorticity levels than normals during diastole is tested and the relationship between RV vorticity and PASP is explored. The mechanics of RV vortex formation are discussed within the context of pulmonary arterial pressure and right ventricular diastolic function coincident with PH.

  2. Blood pressure and left ventricular hypertrophy during American-style football participation.

    Science.gov (United States)

    Weiner, Rory B; Wang, Francis; Isaacs, Stephanie K; Malhotra, Rajeev; Berkstresser, Brant; Kim, Jonathan H; Hutter, Adolph M; Picard, Michael H; Wang, Thomas J; Baggish, Aaron L

    2013-07-30

    Hypertension, a strong determinant of cardiovascular disease risk, has been documented among elite, professional American-style football (ASF) players. The risk of increased blood pressure (BP) and early adulthood hypertension among the substantially larger population of collegiate ASF athletes is not known. We conducted a prospective, longitudinal study to examine BP, the incidence of hypertension, and left ventricular remodeling among collegiate ASF athletes. Resting BP and left ventricular structure were assessed before and after a single season of competitive ASF participation in 6 consecutive groups of first-year university athletes (n=113). ASF participation was associated with significant increases in systolic BP (116±8 versus 125±13 mm Hg; Plife cardiovascular health outcomes in this population.

  3. Silicon determination in human ventricular whole blood: a possible marker of drowning.

    Science.gov (United States)

    Maraschi, Federica; Sturini, Michela; Speltini, Andrea; Orio, Francesco; Profumo, Antonella; Pierucci, Giovanni

    2012-07-15

    This article presents the first results demonstrating that total silicon trace concentration in human ventricular whole blood may be used as a further marker in the diagnosis of drowning. The difference in silicon content between the left and right ventricles was significantly higher for drowning cases than that from individuals who had not drowned. These findings were in full agreement with autoptic responses, supporting silicon as a marker of freshwater drowning. The procedure entails an alkaline microwave-assisted digestion using tetramethylammonium hydroxide (TMAH) in the presence of H(2)O(2) followed by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) detection, whose accuracy was obtained for Seronorm whole blood reference material. Satisfactory recoveries (91-98%) were gained on whole ventricular blood, with a silicon content lower than the method detection limit (MDL), spiked at 5 to 7μgg(-1) with materials consistent with drowning media constituents, that is, freshwater plankton (CRM [certified reference material] 414), silicon dioxide, diatomaceous earth powder, and a silicon standard solution. Good within-lab reproducibility (4-10%) and sensitivity (MDL=0.46μgg(-1)) were achieved as well. The procedure was applied to blood samples from 18 different real cases of death. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. A non-invasive approach to investigation of ventricular blood pressure using cardiac sound features.

    Science.gov (United States)

    Tang, Hong; Zhang, Jinghui; Chen, Huaming; Mondal, Ashok; Park, Yongwan

    2017-02-01

    Heart sounds (HSs) are produced by the interaction of the heart valves, great vessels, and heart wall with blood flow. Previous researchers have demonstrated that blood pressure can be predicted by exploring the features of cardiac sounds. These features include the amplitude of the HSs, the ratio of the amplitude, the systolic time interval, and the spectrum of the HSs. A single feature or combinations of several features have been used for prediction of blood pressure with moderate accuracy. Experiments were conducted with three beagles under various levels of blood pressure induced by different doses of epinephrine. The HSs, blood pressure in the left ventricle and electrocardiograph signals were simultaneously recorded. A total of 31 records (18 262 cardiac beats) were collected. In this paper, 91 features in various domains are extracted and their linear correlations with the measured blood pressures are examined. These features are divided into four groups and applied individually at the input of a neural network to predict the left ventricular blood pressure (LVBP). The analysis shows that non-spectral features can track changes of the LVBP with lower standard deviation. Consequently, the non-spectral feature set gives the best prediction accuracy. The average correlation coefficient between the measured and the predicted blood pressure is 0.92 and the mean absolute error is 6.86 mmHg, even when the systolic blood pressure varies in the large range from 90 mmHg to 282 mmHg. Hence, systolic blood pressure can be accurately predicted even when using fewer HS features. This technique can be used as an alternative to real-time blood pressure monitoring and it has promising applications in home health care environments.

  5. Compact vortices

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Losano, L.; Marques, M.A.; Zafalan, I. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil)

    2017-02-15

    We study a family of Maxwell-Higgs models, described by the inclusion of a function of the scalar field that represent generalized magnetic permeability. We search for vortex configurations which obey first-order differential equations that solve the equations of motion. We first deal with the asymptotic behavior of the field configurations, and then implement a numerical study of the solutions, the energy density and the magnetic field. We work with the generalized permeability having distinct profiles, giving rise to new models, and we investigate how the vortices behave, compared with the solutions of the corresponding standard models. In particular, we show how to build compact vortices, that is, vortex solutions with the energy density and magnetic field vanishing outside a compact region of the plane. (orig.)

  6. Association of white blood cell counts with left ventricular mass index in hypertensive patients undergoing anti-hypertensive drug therapy.

    Science.gov (United States)

    Shi, Hongtao; Chu, Hongxia; Lv, Zhiyang; Qi, Guanming; Guo, Junjie; Fu, Wei; Wang, Xiaojing; Guo, Xiangyu; Ge, Junbo; Yin, Chengqian

    2017-04-01

    Although studies using animal models have demonstrated that nonhemodynamic factors, including inflammatory cells and cytokines, contribute to left ventricular hypertrophy (LVH), there is little clinical data to confirm this association. Therefore in the present study, levels of circulating specific types of leukocyte were measured to determine the association between white blood cells and left ventricular mass index (LVMI) in hypertensive patients undergoing anti-hypertensive drug therapy. A total of 144 consecutive hypertensive patients taking anti-hypertensive drug therapy were enrolled in the current study. Subjects were divided into two groups: Those with normal geometry and those with left LVH. Total white blood cells and differentiated subtypes (neutrophils, lymphocytes, monocytes) were counted, and left ventricular end-diastolic diameter, left ventricular posterior wall thickness in diastole and inter-ventricular septal wall thickness in diastole were all measured. Analysis revealed a significant correlation between LVMI and total white blood cell levels (P=0.013). The percentage of LVH in the highest tertile of WBC was increased compared with the middle tertile (P=0.008). Furthermore, a significant correlation between the highest tertile of neutrophil counts and LVH was observed (P=0.039). However, no significant associations between LVMI and monocyte or lymphocyte counts were detected. Therefore, the current study determined that increased total white blood cell and neutrophil subtype counts were associated with LVMI in hypertensive patients undergoing anti-hypertensive drug therapy. They may provide convenient and useful markers for further risk appraisal of LVH caused by nonhemodynamic factors of hypertension.

  7. Effects of Sevoflurane and Propofol on Organ Blood Flow in Left Ventricular Assist Devices in Pigs

    Directory of Open Access Journals (Sweden)

    Paloma Morillas-Sendín

    2015-01-01

    Full Text Available The aim of this study was to assess the effect of sevoflurane and propofol on organ blood flow in a porcine model with a left ventricular assist device (LVAD. Ten healthy minipigs were divided into 2 groups (5 per group according to the anesthetic received (sevoflurane or propofol. A Biomedicus centrifugal pump was implanted. Organ blood flow (measured using colored microspheres, markers of tissue injury, and hemodynamic parameters were assessed at baseline (pump off and after 30 minutes of partial support. Blood flow was significantly higher in the brain (both frontal lobes, heart (both ventricles, and liver after 30 minutes in the sevoflurane group, although no significant differences were recorded for the lung, kidney, or ileum. Serum levels of alanine aminotransferase and total bilirubin were significantly higher after 30 minutes in the propofol group, although no significant differences were detected between the groups for other parameters of liver function, kidney function, or lactic acid levels. The hemodynamic parameters were similar in both groups. We demonstrated that, compared with propofol, sevoflurane increases blood flow in the brain, liver, and heart after implantation of an LVAD under conditions of partial support.

  8. Experimental testing of a new left ventricular assist device--the microdiagonal blood pump.

    Science.gov (United States)

    Christiansen, Stefan; Demircan, Lütfü; Kwant, Paul B; Akdis, Mustafa; Rex, Steffen; Buhre, Wolfgang; Langebartels, Georg; Kuruc, Norbert; Nikolin, Stefan; Reul, Helmut; Autschbach, Rüdiger

    2004-01-01

    All existing ventricular assist devices are associated with a considerable number of serious complications. This article reports on the first animal tests with a newly developed microdiagonal blood pump (MDP). Six adult female sheep weighing 80 to 90 kg underwent implantation of the microdiagonal blood pump. The inflow and outflow conduits were anastomosed to the left atrium and the descending aorta. Pump flow was adjusted to 2-3 L/minute. Hemodynamic and echocardiographic data, as well as blood samples, were measured over the entire test period of 7 days. All internal organs and the pump were explanted for thorough examination at the end of the trial. Mean arterial (range 88.5 +/- 13.1-103.7 +/- 10.7 mm Hg) and mean pulmonary arterial (18.3 +/- 2.7-21.6 +/- 20.5 mm Hg) pressures, as well as the pulmonary capillary wedge pressure (14.2 +/- 3.0 - 16.6 +/- 4.0 mm Hg), remained stable during the whole test period. Cardiac output (4.9 +/- 0.7 --> 3.2 +/- 0.5 L/minute) decreased postoperatively caused by partial unloading of the heart. Left ventricular end diastolic (4.1 +/- 0.5 --> 3.6 +/- 0.3 cm) and end systolic (3.2 +/- 0.4 --> 2.8 +/- 0.5 cm) diameters, as well as the ejection fraction (57 +/- 9 --> 42 +/- 5%), decreased after MDP implantation and did not change during the test period. Mean number of platelets (428 +/- 54 --> 286 +/- 66 x 10(3)/microL) and hemoglobin (9.8 +/- 1.3 --> 6.3 +/- 0.8 g/dL) decreased perioperatively because of surgical reasons and increased continuously in the postoperative course (platelet count and hemoglobin on day 7:441 +/- 74 x 10(3)/microL and 7.2 +/- 1.1 g/dL, respectively). Free hemoglobin was not enhanced in the postoperative course (mean value during the test period: 18.8 mmoL/L). Histologic examination of the organs did not demonstrate any infarctions of internal organs other than typical operative sequelae such as chronic pericarditis and some degree of atelectasis of the left lungs. These results demonstrate that the

  9. Relationship Between 24-Hour Ambulatory Central Systolic Blood Pressure and Left Ventricular Mass: A Prospective Multicenter Study.

    Science.gov (United States)

    Weber, Thomas; Wassertheurer, Siegfried; Schmidt-Trucksäss, Arno; Rodilla, Enrique; Ablasser, Cornelia; Jankowski, Piotr; Lorenza Muiesan, Maria; Giannattasio, Cristina; Mang, Claudia; Wilkinson, Ian; Kellermair, Jörg; Hametner, Bernhard; Pascual, Jose Maria; Zweiker, Robert; Czarnecka, Danuta; Paini, Anna; Salvetti, Massimo; Maloberti, Alessandro; McEniery, Carmel

    2017-12-01

    We investigated the relationship between left ventricular mass and brachial office as well as brachial and central ambulatory systolic blood pressure in 7 European centers. Central systolic pressure was measured with a validated oscillometric device, using a transfer function, and mean/diastolic pressure calibration. M-mode images were obtained by echocardiography, and left ventricular mass was determined by one single reader blinded to blood pressure. We studied 289 participants (137 women) free from antihypertensive drugs (mean age: 50.8 years). Mean office blood pressure was 145/88 mm Hg and mean brachial and central ambulatory systolic pressures were 127 and 128 mm Hg, respectively. Mean left ventricular mass was 93.3 kg/m2, and 25.6% had left ventricular hypertrophy. The correlation coefficient between left ventricular mass and brachial office, brachial ambulatory, and central ambulatory systolic pressure was 0.29, 0.41, and 0.47, respectively (P=0.003 for comparison between brachial office and central ambulatory systolic pressure and 0.32 for comparison between brachial and central ambulatory systolic pressure). The results were consistent for men and women, and young and old participants. The areas under the curve for prediction of left ventricular hypertrophy were 0.618, 0.635, and 0.666 for brachial office, brachial, and central ambulatory systolic pressure, respectively (P=0.03 for comparison between brachial and central ambulatory systolic pressure). In younger participants, central ambulatory systolic pressure was superior to both other measurements. Central ambulatory systolic pressure, measured with an oscillometric cuff, shows a strong trend toward a closer association with left ventricular mass and hypertrophy than brachial office/ambulatory systolic pressure. URL: https://www.clinicaltrials.gov. Unique identifier: NCT01278732. © 2017 American Heart Association, Inc.

  10. Vitamin D therapy to reduce blood pressure and left ventricular hypertrophy in resistant hypertension: randomized, controlled trial.

    Science.gov (United States)

    Witham, Miles D; Ireland, Sheila; Houston, J Graeme; Gandy, Stephen J; Waugh, Shelley; Macdonald, Thomas M; Mackenzie, Isla S; Struthers, Allan D

    2014-04-01

    Low 25-hydroxyvitamin D levels are associated with higher prevalent blood pressure. We tested whether high-dose intermittent oral vitamin D therapy could reduce blood pressure and left ventricular mass in patients with hypertension resistant to conventional treatment. We conducted a parallel-group, double-blind, randomized placebo-controlled trial. Patients with supine office blood pressure >140/90 mm Hg on ≥3 antihypertensive agents received 100 000 U oral vitamin D3 or matching placebo every 2 months. Office and 24-hour ambulatory blood pressure, glucose, and cholesterol were measured at baseline, 2, 4, and 6 months; left ventricular mass index was measured by cardiac MRI on a subgroup at baseline and 6 months. The primary outcome was mean 24-hour ambulatory blood pressure at 6 months. A total of 68 participants were randomized, 34 in each group. Mean age was 63 (SD 11) years, mean baseline office blood pressure was 154/84 (13/10) mm Hg, and mean baseline 25-hydroxyvitamin D level was 42 (16) nmol/L. Treatment with vitamin D did not reduce 24-hour ambulatory blood pressure (adjusted treatment effects: systolic, +3 mm Hg; 95% confidence interval, -4 to +11; P=0.33; diastolic, -2 mm Hg; 95% confidence interval, -6 to +2; P=0.29); similar results were seen for office blood pressure. Left ventricular mass index was measured in a subgroup (n=25); no reduction was seen with vitamin D treatment (adjusted treatment effect, +4 g/m(2); 95% confidence interval, 0 to +7; P=0.04). There was no significant change in cholesterol or glucose levels. Thus, 6 months of intermittent, high-dose oral vitamin D3 did not reduce blood pressure or left ventricular mass in patients with resistant hypertension.

  11. Home versus office blood pressure: longitudinal relations with left ventricular hypertrophy: the Finn-Home study.

    Science.gov (United States)

    Sivén, Sam S E; Niiranen, Teemu J; Langén, Ville L J; Puukka, Pauli J; Kantola, Ilkka M; Jula, Antti M

    2017-02-01

    Electrocardiographically assessed left-ventricular hypertrophy (ECG-LVH) is a particularly high-risk phenomenon that is a part of every hypertensive patient's initial work-up. Several cross-sectional studies have demonstrated that home blood pressure (BP) has a stronger relation to LVH than office BP. However, longitudinal evidence on the association between home BP and target organ damage is scarce to nonexistent. We studied in a sample of 615 community-dwelling participants (mean age at baseline 53.7 ± 7.2, 58% women) whether change in home BP is more strongly associated with change in ECG-LVH than change in office BP over an 11-year follow-up. Pearson's correlation coefficients between changes in home/office SBP and changes in Sokolow-Lyon index, Cornell voltage, Cornell product and R wave amplitude in aVL were 0.21/0.18, 0.28/0.17, 0.25/0.16, and 0.32/0.20, respectively (asterisk indicates P home/office DBP and change in the aforementioned ECG-LVH indexes, the correlations were 0.12/0.12, 0.20/0.15, 0.16/0.12, and 0.28/0.19. Multivariable-adjusted regression modelling provided similar results. No clinically significant increase in correlations between home BP and ECG-LVH indexes occurred after the fourth day of home BP measurement. Our study demonstrates for the first time the superiority of home BP over office BP in the follow-up of left ventricular mass. The results of this and previous studies underline the importance of using out-of-office BP measurements as the primary method for assessing blood pressure levels.

  12. Are the metabolic syndrome, blood pressure pattern, and their interaction responsible for the right ventricular remodeling?

    Science.gov (United States)

    Tadic, Marijana; Ivanovic, Branislava; Celic, Vera; Cuspidi, Cesare

    2013-08-01

    The aim of our study was to define the relationship between the metabolic syndrome (MS), nondipping pattern, and their interaction on right ventricular (RV) structural and functional changes in untreated hypertensive patients. This cross-sectional study included 318 recently diagnosed hypertensive patients. MS was defined by the presence of at least 3 National Cholesterol Education Program's Adult Treatment Panel III criteria. All patients underwent 24-h ambulatory blood pressure monitoring and a complete two-dimensional echocardiography examination. MS was found in 144 (45%) hypertensive patients and the nondipping pattern was detected in 147 (46%) patients. Hypertensive patients with MS had higher 24-h and night-time blood pressure levels in comparison with non-MS patients with the same nocturnal blood pressure pattern. RV wall thickness was significantly increased and RV diastolic function was significantly deteriorated in nondippers (with and without MS), but still more impaired in MS patients. MS, nondipping pattern, and their interaction had a huge impact on RV wall thickness, parameters of RV diastolic function (E/At, E/e't, e'/a't), as well as RV global function estimated by the myocardial performance index. Among the MS criteria, only fasting glucose level and abdominal obesity were associated independently with RV hypertrophy, diastolic, and global dysfunction. MS, nondipping pattern, and their interaction significantly impact RV structure, diastolic, and global function. Fasting glucose level and abdominal obesity are the most important MS criteria for RV remodeling in arterial hypertension.

  13. Anatomy and Physiology of Left Ventricular Suction Induced by Rotary Blood Pumps.

    Science.gov (United States)

    Salamonsen, Robert Francis; Lim, Einly; Moloney, John; Lovell, Nigel Hamilton; Rosenfeldt, Franklin L

    2015-08-01

    This study in five large greyhound dogs implanted with a VentrAssist left ventricular assist device focused on identification of the precise site and physiological changes induced by or underlying the complication of left ventricular suction. Pressure sensors were placed in left and right atria, proximal and distal left ventricle, and proximal aorta while dual perivascular and tubing ultrasonic flow meters measured blood flow in the aortic root and pump outlet cannula. When suction occurred, end-systolic pressure gradients between proximal and distal regions of the left ventricle on the order of 40-160 mm Hg indicated an occlusive process of variable intensity in the distal ventricle. A variable negative flow difference between end systole and end diastole (0.5-3.4 L/min) was observed. This was presumably mediated by variable apposition of the free and septal walls of the ventricle at the pump inlet cannula orifice which lasted approximately 100 ms. This apposition, by inducing an end-systolic flow deficit, terminated the suction process by relieving the imbalance between pump requirement and delivery from the right ventricle. Immediately preceding this event, however, unnaturally low end-systolic pressures occurred in the left atrium and proximal left ventricle which in four dogs lasted for 80-120 ms. In one dog, however, this collapse progressed to a new level and remained at approximately -5 mm Hg across four heart beats at which point suction was relieved by manual reduction in pump speed. Because these pressures were associated with a pulmonary capillary wedge pressure of -5 mm Hg as well, they indicate total collapse of the entire pulmonary venous system, left atrium, and left ventricle which persisted until pump flow requirement was relieved by reducing pump speed. We suggest that this collapse caused the whole vascular region from pulmonary capillaries to distal left ventricle to behave as a Starling resistance which further reduced right

  14. Blood PGC-1α Concentration Predicts Myocardial Salvage and Ventricular Remodeling After ST-segment Elevation Acute Myocardial Infarction.

    Science.gov (United States)

    Fabregat-Andrés, Óscar; Ridocci-Soriano, Francisco; Estornell-Erill, Jordi; Corbí-Pascual, Miguel; Valle-Muñoz, Alfonso; Berenguer-Jofresa, Alberto; Barrabés, José A; Mata, Manuel; Monsalve, María

    2015-05-01

    Peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) is a metabolic regulator induced during ischemia that prevents cardiac remodeling in animal models. The activity of PGC-1α can be estimated in patients with ST-segment elevation acute myocardial infarction. The aim of the present study was to evaluate the value of blood PGC-1α levels in predicting the extent of necrosis and ventricular remodeling after infarction. In this prospective study of 31 patients with a first myocardial infarction in an anterior location and successful reperfusion, PGC-1α expression in peripheral blood on admission and at 72 hours was correlated with myocardial injury, ventricular volume, and systolic function at 6 months. Edema and myocardial necrosis were estimated using cardiac magnetic resonance imaging during the first week. At 6 months, infarct size and ventricular remodeling, defined as an increase > 10% of the left ventricular end-diastolic volume, was evaluated by follow-up magnetic resonance imaging. Myocardial salvage was defined as the difference between the edema and necrosis areas. Greater myocardial salvage was seen in patients with detectable PGC-1α levels at admission (mean [standard deviation (SD)], 18.3% [5.3%] vs 4.5% [3.9%]; P = .04). Induction of PGC-1α at 72 hours correlated with greater ventricular remodeling (change in left ventricular end-diastolic volume at 6 months, 29.7% [11.2%] vs 1.2% [5.8%]; P = .04). Baseline PGC-1α expression and an attenuated systemic response after acute myocardial infarction are associated with greater myocardial salvage and predict less ventricular remodeling. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  15. Left ventricular mass index and sports: the influence of different sports activities and arterial blood pressure.

    Science.gov (United States)

    Iglesias Cubero, G; Batalla, A; Rodriguez Reguero, J J; Barriales, R; González, V; de la Iglesia, J L; Terrados, N

    2000-09-15

    The mechanisms by which endurance training produces physiological hypertrophy have been thoroughly investigated but not with young athletes. The aim of our study was to investigate arterial blood pressure exercise responses in young athletes who started heavy training by the age of 11, participating in metabolically different sports (cycling, kayaking, and soccer) and to analyse the influence that arterial blood pressure at maximum exercise and VO(2) max could have on the development of cardiac mass in these subjects. We studied a group of well trained normotensive male subjects, comprising 37 cyclists, 15 soccer players and 12 canoeists (mean age, 16+/-1 years). Evaluation included a clinical history and physical examination, M-mode and two-dimensional echocardiography, 12-lead resting electrocardiogram and a graded exercise test with direct determination of VO(2) max. Systolic and diastolic blood pressure were measured at rest and maximum exercise. Determination of the left ventricular mass index (LVMI) was performed using Devereux's formula with correction for the body surface area. Cyclists showed values of LVMI in g m(-2) significantly higher than those of other subjects (123 vs. 92 and 113). Canoeists showed the maximal arterial blood pressure at maximum exercise in mmHg (190 vs. 172 and 170) and cyclists showed the maximal VO(2) ml kg(-1) min(-1) uptake (57.6 vs. 48.5 and 53.3). A linear correlation was found between LVMI and VO(2) max (r=0.4727, P<0.001) and this correlation was also significant with systolic blood pressure at maximum exercise (r=0.2909, P<0.01). No differences in LVMI were found when comparing those subjects who presented systolic blood pressure at maximum exercise equal or greater than 195 mmHg with those who presented less than this value. It can be concluded that VO(2) max is the variable that better correlates with the LVMI. Athletes who reach greater systolic blood pressures at peak exercise have a tendency to develop greater LVMI. In

  16. Three dimensional quantification of left ventricular wall motion by ECG-gated blood pool emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, S.R.; Walton, S.; Laming, P.J.; Jarritt, P.H.; Ell, P.J.; Emanuel, R.W.; Swanton, R.H.

    1985-05-01

    ECG-gated blood pool emission tomography is a relatively new technique, and this study establishes a simple method for displaying the three dimensional data obtained, determines a normal range for ejection fraction in all regions of the left ventricle, and compares wall motion in abnormal subjects with that determined by X-ray contrast ventriculography. The short axis sections dividing the ventricle in slices from apex to base, were used to calculate ejection fraction for all parts of the ventricle and the results were plotted on a single colour coded circular image. The apex was represented in the centre, the base around the circumference, and all other parts of the ventricle were represented in between. The image was divided into 15 segments, and normal segmental ejection fraction was defined as within two standard deviations of the mean in a group of 10 normal subjects. In 25 subjects with coronary artery disease, motion of the anterior, apical, and inferior walls agreed in every case with the right anterior oblique contrast ventriculogram, but in 12 of these, the three dimensional ejection fraction image showed abnormal septal motion, and in a further 3, abnormal lateral wall motion in addition. In the 12 subjects there was disease of the left anterior descending coronary artery, and in the further 3 there was left circumflex disease. ECG-gated blood pool emission tomography thus provides an accurate quantitative assessment of left ventricular wall motion in three dimensions, and has significant advantages over conventional planar techniques.

  17. Partitioned fluid-solid coupling for cardiovascular blood flow: left-ventricular fluid mechanics.

    Science.gov (United States)

    Krittian, Sebastian; Janoske, Uwe; Oertel, Herbert; Böhlke, Thomas

    2010-04-01

    We present a 3D code-coupling approach which has been specialized towards cardiovascular blood flow. For the first time, the prescribed geometry movement of the cardiovascular flow model KaHMo (Karlsruhe Heart Model) has been replaced by a myocardial composite model. Deformation is driven by fluid forces and myocardial response, i.e., both its contractile and constitutive behavior. Whereas the arbitrary Lagrangian-Eulerian formulation (ALE) of the Navier-Stokes equations is discretized by finite volumes (FVM), the solid mechanical finite elasticity equations are discretized by a finite element (FEM) approach. Taking advantage of specialized numerical solution strategies for non-matching fluid and solid domain meshes, an iterative data-exchange guarantees the interface equilibrium of the underlying governing equations. The focus of this work is on left-ventricular fluid-structure interaction based on patient-specific magnetic resonance imaging datasets. Multi-physical phenomena are described by temporal visualization and characteristic FSI numbers. The results gained show flow patterns that are in good agreement with previous observations. A deeper understanding of cavity deformation, blood flow, and their vital interaction can help to improve surgical treatment and clinical therapy planning.

  18. Impact of central haemodynamics on left ventricular function in individuals with an exaggerated blood pressure response to exercise.

    Science.gov (United States)

    Shim, Chi Young; Hong, Geu-Ru; Park, Sungha; Yang, Woo-In; Choi, Donghoon; Chung, Namsik; Ha, Jong-Won

    2015-03-01

    The impact of exaggerated blood pressure response (EBPR) to exercise on left ventricular function and the mechanism of its association are poorly understood. This study investigated the impact of arterial stiffening on left ventricular function in individuals with an EBPR to exercise. We hypothesized that individuals with low pulse pressure (PP) amplification during exercise would have worse left ventricular function than those with high PP amplification in individuals with an EBPR to exercise. Fifty-nine individuals with an EBPR to exercise (18 men, age 57 ± 12 years) and 59 age and sex-matched controls were studied. Radial artery tonometry was performed at rest and immediately after exercise during supine bicycle exercise echocardiography. There were no differences in left ventricular structure or function between individuals with an EBPR to exercise and controls. When individuals with an EBPR to exercise were divided into two groups on the basis of PP amplification after exercise [Group 1 (n = 30), high PP amplification after exercise; Group 2 (n = 29), low PP amplification after exercise], group 2 showed larger left atrial volume and lower early diastolic (e') and systolic (S') mitral annular velocities. Left ventricular apical rotation was also exaggerated in group 2. In multiple regression, PP amplification after exercise was an independent determinant of e' (β = 0.16, P = 0.019) and S' (β = 0.25, P = 0.009) in individuals with an EBPR to exercise. In individuals with an EBPR to exercise, the degree of left ventricular dysfunction is variable. EBPR to exercise in the presence of arterial stiffening contributes to the deterioration of left ventricular function.

  19. Left ventricular volume unloading with axial and centrifugal rotary blood pumps.

    Science.gov (United States)

    Giridharan, Guruprasad A; Koenig, Steven C; Soucy, Kevin G; Choi, Young; Pirbodaghi, Tohid; Bartoli, Carlo R; Monreal, Gretel; Sobieski, Michael A; Schumer, Erin; Cheng, Allen; Slaughter, Mark S

    2015-01-01

    Axial (AX) and centrifugal (CFG) rotary blood pumps have gained clinical acceptance for the treatment of advanced heart failure. Differences between AX and CFG designs and mechanism of blood flow delivery may offer clinical advantages. In this study, pump characteristics, and acute physiologic responses during support with AX (HeartMate II) and CFG (HVAD) left ventricular assist devices (LVAD) were investigated in mock loop and chronic ischemic heart failure bovine models. In the mock loop model, pump performance was characterized over a range of pump speeds (HeartMate II: 7,000-11,000 rpm, HVAD: 2,000-3,600 rpm) and fluid viscosities (2.7 cP, 3.2 cP, 3.7 cP). In the ischemic heart failure bovine model, hemodynamics, echocardiography, and end-organ perfusion were investigated. CFG LVAD had a flatter HQ curve, required less power, and had a more linear flow estimation relation than AX LVAD. The flow estimation error for the AX LVAD (±0.9 L/min at 2.7 cP, ±0.7 L/min at 3.2 cP, ±0.8 L/min at 3.7 cP) was higher than the CFG LVAD (±0.5 L/min at 2.7 cP, ±0.2 L/min at 3.2 cP, ±0.5 L/min at 3.7 cP). No differences in acute hemodynamics, echocardiography, or end-organ perfusion between AX and CFG LVAD over a wide range of support were statistically discernible. These findings suggest no pronounced acute differences in LV volume unloading between AX and CFG LVAD.

  20. Mathematical Modeling of a Blood Flow in Flow Path of the Axial Pump of Ventricular Assist Device

    OpenAIRE

    A. M. Guskov; F. D. Sorokin; E. P. Banin; A. E. Krupnin

    2015-01-01

    The research object is an axial left ventricular assist device (LVAD) design such as: straightener, impeller, and diffuser.The objective of the study is to reveal an influence of axial LVAD pump’s impeller design factors such as pitch and incidence on head-capacity curves and stagnation and hemolysis zones generation. The mathematical modeling is carried out by computational fluid dynamics analysis in a stationary setting.The study concentrates on mathematical modeling of a blood flow in flow...

  1. Coronary to pulmonary fistula as the primary source of pulmonary blood supply in pulmonary atresia with ventricular septal defect

    OpenAIRE

    Isman Firdaus; Cholid T. Tjahjono; Ganesja H. Harimurti; Poppy S. Roebiono

    2004-01-01

    A communication between the coronary and pulmonary arteries, so called coronary to pulmonary fistula, is a rare source of pulmonary supply in pulmonary atresia (PA) with ventricular septal defect (VSD). A 4 year old girl referred to National Cardiovascular Center Harapan Kita, Jakarta with symptoms and signs of increased pulmonary blood flow since infancy and was confirmed by the chest x-rays. Heart examination revealed normal first heart sound with single loud second heart sound and an eject...

  2. In vivo experimental testing of the FW axial blood pump for left ventricular support in Fu Wai Hospital.

    Science.gov (United States)

    Zhang, Yan; Hu, Sheng-Shou; Zhou, Jian-Ye; Sun, Han-Song; Tang, Yue; Zhang, Hao; Zheng, Zhe; Li, Guo-Rong; Zhu, Xiao-Dong; Gui, Xin-Min

    2009-01-01

    A fully implantable, axial flow blood pump has been developed in Fu Wai Hospital aiming for clinical use. This ventricular assist device (VAD), which was developed after numerous CFD analyses for the flow characteristics of the pump, is 58.5-mm long, 30-mm wide (including DC motor), and weighs 240 g. The pump can deliver 5 L/min for pressures of 100 mm Hg over 8,000 rpm. In this study, short-term hemocompatibility effects of the axial left ventricular assist device (LVAD) (FW blood pump) were evaluated in four healthy sheep. The device was implanted into the left ventricular apex of beating hearts. The outflow graft of each device was anastomosed to the descending aorta. The hemolysis, which was evaluated in vivo by free hemoglobin value, was below 30 mg/dL. Evaluation of serum biochemical data showed that implantation of the FW blood pump in sheep with normal hearts did not impair end organ function. Gross and microscopic sections of kidney, liver, and lung revealed no evidence of microemboli. Performance of the pump in vivo was considered sufficient for a LVAD, although further design improvement is necessary in terms of hemolysis and antithrombosis to improve biocompatibility of the pump.

  3. Soybean oil increases SERCA2a expression and left ventricular contractility in rats without change in arterial blood pressure

    Directory of Open Access Journals (Sweden)

    Vassallo Dalton

    2010-05-01

    Full Text Available Abstract Background Our aim was to evaluate the effects of soybean oil treatment for 15 days on arterial and ventricular pressure, myocardial mechanics and proteins involved in calcium handling. Methods Wistar rats were divided in two groups receiving 100 μL of soybean oil (SB or saline (CT i.m. for 15 days. Ventricular performance was analyzed in male 12-weeks old Wistar rats by measuring left ventricle diastolic and systolic pressure in isolated perfused hearts according to the Langendorff technique. Protein expression was measured by Western blot analysis. Results Systolic and diastolic arterial pressures did not differ between CT and SB rats. However, heart rate was reduced in the SB group. In the perfused hearts, left ventricular isovolumetric systolic pressure was higher in the SB hearts. The inotropic response to extracellular Ca2+ and isoproterenol was higher in the soybean-treated animals than in the control group. Myosin ATPase and Na+-K+ATPase activities, the expression of sarcoplasmic reticulum calcium pump (SERCA2a and sodium calcium exchanger (NCX were increased in the SB group. Although the phosfolamban (PLB expression did not change, its phosphorylation at Ser16 was reduced while the SERCA2a/PLB ratio was increased. Conclusions In summary, soybean treatment for 15 days in rats increases the left ventricular performance without affecting arterial blood pressure. These changes might be associated with an increase in the myosin ATPase activity and SERCA2a expression.

  4. Improving left ventricular segmentation in four-dimensional flow MRI using intramodality image registration for cardiac blood flow analysis.

    Science.gov (United States)

    Gupta, Vikas; Bustamante, Mariana; Fredriksson, Alexandru; Carlhäll, Carl-Johan; Ebbers, Tino

    2018-01-01

    Assessment of blood flow in the left ventricle using four-dimensional flow MRI requires accurate left ventricle segmentation that is often hampered by the low contrast between blood and the myocardium. The purpose of this work is to improve left-ventricular segmentation in four-dimensional flow MRI for reliable blood flow analysis. The left ventricle segmentations are first obtained using morphological cine-MRI with better in-plane resolution and contrast, and then aligned to four-dimensional flow MRI data. This alignment is, however, not trivial due to inter-slice misalignment errors caused by patient motion and respiratory drift during breath-hold based cine-MRI acquisition. A robust image registration based framework is proposed to mitigate such errors automatically. Data from 20 subjects, including healthy volunteers and patients, was used to evaluate its geometric accuracy and impact on blood flow analysis. High spatial correspondence was observed between manually and automatically aligned segmentations, and the improvements in alignment compared to uncorrected segmentations were significant (P flow analysis from manual and automatically corrected segmentations did not differ significantly (P > 0.05). Our results demonstrate the efficacy of the proposed approach in improving left-ventricular segmentation in four-dimensional flow MRI, and its potential for reliable blood flow analysis. Magn Reson Med 79:554-560, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  5. Guiding Hypertension Management Using Central Blood Pressure: Effect of Medication Withdrawal on Left Ventricular Function.

    Science.gov (United States)

    Kosmala, Wojciech; Marwick, Thomas H; Stanton, Tony; Abhayaratna, Walter P; Stowasser, Michael; Sharman, James E

    2016-03-01

    Central blood pressure (BP) is an acknowledged contributor to end-organ damage and independent determinant of prognosis. Primary analysis from the BPGUIDE study demonstrated no detriment on left ventricular (LV) structure from central BP-guided hypertension management, despite significant medication withdrawal. However, the effect of this on LV function has not been investigated. In this study, we sought to investigate the impact of central BP-guided hypertension management on LV systolic and diastolic performance. A total of 286 enrollees with uncomplicated hypertension were randomized to therapeutic decisions guided by best-practice usual care (UC) or, in addition, by central BP intervention (CBP) for 12 months. Each participant underwent baseline and follow-up 2-dimensional echocardiography, with assessment undertaken by an expert blinded to participant allocation. Antihypertensive medication quantity remained unchanged for UC but significantly decreased with intervention. However, no significant between-group differences were noted for changes during follow-up in both brachial and central BP, as well as other central hemodynamic parameters: augmentation index and augmented pressure. Similarly, there were no differences between groups in parameters of LV diastolic function: tissue e' velocity (∆UC vs. ∆CBP; P = 0.27) and E/e' ratio (∆UC vs. ∆CBP; P = 0.60), and systolic parameters: LV longitudinal strain (∆UC vs. ∆CBP; P = 0.55), circumferential strain (∆UC vs. ∆CBP; P = 0.79), and ejection fraction (∆UC vs. ∆CBP; P = 0.15). Hypertension management guided by central BP, resulting in significant withdrawal of medication to maintain appropriate BP control, had no adverse effect on LV systolic or diastolic function. Clinical trials registration: Australia New Zealand Clinical Trial Registry Number ACTRN12608 000041358. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Relationship of Office and Ambulatory Blood Pressure With Left Ventricular Global Longitudinal Strain.

    Science.gov (United States)

    Sera, Fusako; Jin, Zhezhen; Russo, Cesare; Lee, Edward S; Schwartz, Joseph E; Rundek, Tatjana; Elkind, Mitchell S V; Homma, Shunichi; Sacco, Ralph L; Di Tullio, Marco R

    2015-12-07

    Left ventricular (LV) global longitudinal strain (GLS) is an early indicator of subclinical cardiac dysfunction, even when LV ejection fraction (LVEF) is normal, and is an independent predictor of cardiovascular events. Ambulatory blood pressure (BP) is a better predictor of cardiovascular events, including heart failure, than office BP. We investigated the association of office and ambulatory BP measurements with subclinical LV systolic dysfunction in a community-based cohort with normal LVEF. Two-dimensional speckle-tracking echocardiography and 24-hour ambulatory BP monitoring were performed in 577 participants (mean age 70±9 years; 60% women) with LVEF ≥50% from the Cardiovascular Abnormalities and Brain Lesions (CABL) study. Univariable and multivariable linear regression analyses were used to assess the associations of BP measures with GLS. Higher ambulatory and office BP values were consistently associated with impaired GLS. After adjustment for pertinent covariates (age, sex, race/ethnicity, body mass index, diabetes mellitus, coronary artery disease, LV mass index, and antihypertensive medication), office diastolic BP and ambulatory systolic and diastolic BPs (24-hour, daytime and nighttime) were independently associated with GLS (P = 0.003 for office DBP, P ≤ 0.001 for all ambulatory BPs). When ambulatory and office BP values were included in the same model, all ambulatory BP measures remained significantly associated with GLS (all P Ambulatory BP values are significantly associated with impaired GLS and the association is stronger than for office BP. Ambulatory BP monitoring might have a role in the risk stratification of hypertensive patients for early LV dysfunction. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Factors affecting left ventricular synchronicity in hypertensive patients: are arterial stiffness and central blood pressures influential?

    Science.gov (United States)

    Kırış, Abdulkadir; Kırış, Gülhanım; Karaman, Kayıhan; Sahin, Mürsel; Gedikli, Omer; Kaplan, Sahin; Orem, Asım; Kutlu, Merih; Kazaz, Zeynep

    2012-10-01

    Left ventricular (LV) dyssynchrony is a common finding in patients with hypertension and is associated with LV hypertrophy. Arterial stiffness (AS) and central (aortic) blood pressures play a significant role in end-organ damage such as LV hypertrophy caused by hypertension. The objective of this study was to investigate the relationship between AS, central blood pressures (BP) and LV dyssynchrony. Thirty-five newly diagnosed hypertensive patients and 40 controls were enrolled in the study. The entire study population underwent a comprehensive echocardiographic study including tissue synchrony imaging. The 12 segmental model was used to measure the time to regional peak systolic tissue velocity (Ts) in the LV and two dyssynchrony indices were computed. Parameters of AS including pulse wave velocity (PWV), augmentation index (AIx@75), and central systolic and diastolic BP were evaluated by applanation tonometry. The baseline clinical and echocardiographic parameters of both groups were similar except for their BPs. Dyssynchrony indices were prolonged in patients with hypertension as compared to the controls. The standart deviation of Ts of 12 LV segments in patients with hypertension and the controls were 48.7±18.8 vs. 25.8±13.1, respectively (p<0.001), and the maximal difference in Ts between any 2 of 12 LV segments was 143.9±52.2 for hypertension patients vs. 83.8±39.4 for controls (p<0.001). PWV (11.9±2.5 vs. 9.5±1.4, p<0.001), AIx@75 (27.4±8.3 vs. 18.3±9, p=0.009), and central systolic (147.6±20.8 vs. 105.4±11, p<0.001) and diastolic (99.8±14.4 vs. 72.8±9.5, p<0.001) pressures were higher in patients with hypertension than in the controls, respectively. In multivariable analysis, central systolic BP (ß=0.496, p=0.03), LV mass index (ß=0.232, p=0.027), and body mass index (ß=0.308, p=0.002) were found to be independently related to dyssynchrony. Central systolic BP is an independent predictor of LV dyssynchrony, but Aıx@75 did not have an

  8. Estimation of left ventricular blood flow parameters: clinical application of patient-specific CFD simulations from 4D echocardiography

    Science.gov (United States)

    Larsson, David; Spühler, Jeannette H.; Günyeli, Elif; Weinkauf, Tino; Hoffman, Johan; Colarieti-Tosti, Massimiliano; Winter, Reidar; Larsson, Matilda

    2017-03-01

    Echocardiography is the most commonly used image modality in cardiology, assessing several aspects of cardiac viability. The importance of cardiac hemodynamics and 4D blood flow motion has recently been highlighted, however such assessment is still difficult using routine echo-imaging. Instead, combining imaging with computational fluid dynamics (CFD)-simulations has proven valuable, but only a few models have been applied clinically. In the following, patient-specific CFD-simulations from transthoracic dobutamin stress echocardiography have been used to analyze the left ventricular 4D blood flow in three subjects: two with normal and one with reduced left ventricular function. At each stress level, 4D-images were acquired using a GE Vivid E9 (4VD, 1.7MHz/3.3MHz) and velocity fields simulated using a presented pathway involving endocardial segmentation, valve position identification, and solution of the incompressible Navier-Stokes equation. Flow components defined as direct flow, delayed ejection flow, retained inflow, and residual volume were calculated by particle tracing using 4th-order Runge-Kutta integration. Additionally, systolic and diastolic average velocity fields were generated. Results indicated no major changes in average velocity fields for any of the subjects. For the two subjects with normal left ventricular function, increased direct flow, decreased delayed ejection flow, constant retained inflow, and a considerable drop in residual volume was seen at increasing stress. Contrary, for the subject with reduced left ventricular function, the delayed ejection flow increased whilst the retained inflow decreased at increasing stress levels. This feasibility study represents one of the first clinical applications of an echo-based patient-specific CFD-model at elevated stress levels, and highlights the potential of using echo-based models to capture highly transient flow events, as well as the ability of using simulation tools to study clinically complex

  9. Features of left ventricular hypertrophy in patients with metabolic syndrome with or without comparable blood pressure: a meta-analysis.

    Science.gov (United States)

    Li, Ning-Yin; Yu, Jing; Zhang, Xiao-Wei; Wang, Shi-Xiong; Chang, Peng; Ding, Qi; Ma, Rui-Xin; Chen, Qun-Fei; Zhao, Feng; Bai, Feng

    2013-06-01

    The prevalence of metabolic syndrome (MS) has been on the rise over the past few decades, and this is associated with an increased incidence of target organ damage such as left ventricular hypertrophy (LVH). This meta-analysis aims to evaluate the features of LVH in MS patients with or without high blood pressure (BP). PubMed, Cochrane Library, Embase, Science Citation Index, and China Biology Medicine Disc, WanFang data, China National Knowledge Infrastructure database, and VIP were searched. Cross-sectional studies which directly compared LVH in hypertensive patients with MS and those with hypertension alone were identified. The following parameters were analyzed: systolic blood pressure (SBP), diastolic blood pressure (DBP), left ventricular mass (LVM), left ventricular mass index (LVMI), left ventricular mass/height(2.7) (LVM/h(2.7)), interventricular septum thickness (IVSt), left ventricular end-diastolic diameter (LVEDd), left ventricular posterior wall (LVPW), ratio of early to late diastolic peak flow velocity (E/A), and relative wall thickness (RWT). Data were extracted and analyzed by Cochrane Collaboration's RevMan 5.0 software. 14 studies involving 5,994 patients were included. In four studies, MS patients with comparable level of BP had higher SBP (mmHg) [Mean Difference (MD) = 2.28, 95 % confidence intervals (CI): -0.58 to 5.13], DBP (mmHg) (MD = 1.32, 95 % CI: -0.23 to 2.87), LVM (g) (MD = 42.10, 95 % CI: 6.92-77.28), LVMI (g/m(2)) (MD = 8.93, 95 % CI: 5.29-12.57), LVM/h(2.7) (g/m(2.7)) (MD = 5.40, 95 % CI: 2.51-8.29), IVSt (mm) (MD = 0.49, 95 % CI: 0.28-0.71), LVEDd (mm) (MD = 1.04, 95 % CI: -1.10 to 3.18), LVPW (mm) (MD = 0.75, 95 % CI: 0.13-1.37), RWT (MD = 0.06, 95 % CI: -0.00 to 0.12), and lower E/A (MD = -0.08, 95 % CI: -0.18 to 0.02) when compared to the patients with hypertension alone. In other ten studies, the hypertensive patients with MS exhibited higher levels of SBP (mmHg) (MD = 4.67, 95 % CI: 2.72-6.62), DBP (mmHg) (MD = 2.03,95 % CI

  10. Impact of abdominal obesity and ambulatory blood pressure in the diagnosis of left ventricular hypertrophy in never treated hypertensives.

    Science.gov (United States)

    Rodilla, Enrique; Costa, José A; Martín, Joaquin; González, Carmen; Pascual, Jose M; Redon, Josep

    2014-03-20

    The principal objective was to assess the prevalence of left ventricular hypertrophy (LVH) in hypertensive, never treated patients, depending on adjustment for body surface or height. Secondary objectives were to determine geometric alterations of the left ventricle and to analyze the interdependence of hypertension and obesity to induce LVH. Cross-sectional study that included 750 patients (387 men) aged 47 (13, SD) years who underwent ambulatory blood pressure (ABPM) monitoring and echocardiography. The prevalence of LVH was 40.4% (303 patients), adjusted for body surface area (BSA, LVHBSA), and 61.7% (463 patients), adjusted for height(2.7) (LVHheight(2.7)). In a multivariate logistic analysis, systolic BP24h, gender and presence of elevated microalbuminuria were associated with both LVHBSA and LVHheight(2.7). Increased waist circumference was the strongest independent predictor of LVHheight(2.7), but was not associated with LVHBSA. We found a significant interaction between abdominal obesity and systolic BP24h in LVHheight(2.7). Concentric remodelling seems to be the most prevalent alteration of left ventricular geometry in early stages of hypertension (37.5%). The impact of obesity as predictor of LVH in never treated hypertensives is present only when left ventricular mass (LVM) is indexed to height(2.7). Obesity interacts with systolic BP24h in an additive but not merely synergistic manner. Systolic BP24h is the strongest determinant of LVH when indexed for BSA. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  11. Gradient and vorticity banding

    NARCIS (Netherlands)

    Dhont, Jan K.G.; Briels, Willem J.

    2008-01-01

    "Banded structures" of macroscopic dimensions can be induced by simple shear flow in many different types of soft matter systems. Depending on whether these bands extend along the gradient or vorticity direction, the banding transition is referred to as "gradient banding" or "vorticity banding,"

  12. Blood Pressure and Left Ventricular Characteristics in Young Patients with Classical Congenital Adrenal Hyperplasia due to 21-Hydroxylase Deficiency

    Directory of Open Access Journals (Sweden)

    Ubertini Graziamaria

    2010-01-01

    Full Text Available High steroid doses are often necessary in congenital adrenal hyperplasia (CAH to suppress androgens and may increase blood pressure (BP. We evaluated 24-hour BP profile (ambBP, BP during exercise (excBP, and echocardiography in 20 young CAH patients. Systolic and diastolic BP during ambBP and excBP was normal in all patients. None presented myocardial hypertrophy. Nocturnal diastolic BP was affected by testosterone (: .016, 95% CI: 0.002 to 0.021, = 0.01. Left ventricular mass (LVM was affected by height SDS (: .007, 95% CI: 2.67 to 14.17, = 8.42, age (: , 95% CI: 2.12 to 5.82, = 3.97, and testosterone (: .008, 95% CI: 0.01 to 0.09, = 0.053. Left ventricular mass index (LVMI correlated with BMI SDS (: .044, 95% CI: 0.09 to 6.17, = 3.13 and testosterone (: .031, 95% CI: 0.002 to 0.035, = 0.018. Hydrocortisone dose did not influence ambBP, excBP, or myocardial hypertrophy.

  13. Coronary to pulmonary fistula as the primary source of pulmonary blood supply in pulmonary atresia with ventricular septal defect

    Directory of Open Access Journals (Sweden)

    Isman Firdaus

    2004-12-01

    Full Text Available A communication between the coronary and pulmonary arteries, so called coronary to pulmonary fistula, is a rare source of pulmonary supply in pulmonary atresia (PA with ventricular septal defect (VSD. A 4 year old girl referred to National Cardiovascular Center Harapan Kita, Jakarta with symptoms and signs of increased pulmonary blood flow since infancy and was confirmed by the chest x-rays. Heart examination revealed normal first heart sound with single loud second heart sound and an ejection systolic murmur at the pulmonary area. ECG demonstrated sinus rhythm with normal axis and biventricular hypertrophy. Echocardiography was performed and truncus arteriosus (TA type I was suspected with perimembranus VSD, overriding of the aorta, and dilated main pulmonary artery. But on cardiac catheterization studies, a non obstructive fistula was found between the left coronary and main pulmonary artery coexisted with PA and VSD. A successful surgery was performed subsequently and confirmed the above diagnosis. Although there were episodes of pulmonary hypertension crisis during early post operative course, she was then discharge from the hospital in a good condition. Since irreversible pulmonary vascular disease may develop in a non restrictive coronary to pulmonary fistula, early recognition of this anomaly is very important for better surgical result. (Med J Indones 2004; 13: 237-40Keywords: coronary to pulmonary fistula, pulmonary atresia, ventricular septal defect

  14. Evaluation of right ventricular function by NuSMUGA software : gated blood-pool SPECT vs. first-pass radionuclide angiography

    NARCIS (Netherlands)

    Slart, RHJA; Poot, L; Piers, DA; van Veldhuisen, DJ; Jager, PL

    2003-01-01

    Background: In comparison with planar imaging gated blood-pool single photon emission computed tomography (GBPS) has the advantage of separating left and right ventricle. The purpose of this investigation was to evaluate the right ventricular ejection fraction (RVEF) calculations by GBPS software

  15. Vorticity and vortex dynamics

    CERN Document Server

    Wu, Jie-Zhi; Zhou, M-D

    2006-01-01

    The importance of vorticity and vortex dynamics has now been well rec- nized at both fundamental and applied levels of ?uid dynamics, as already anticipatedbyTruesdellhalfcenturyagowhenhewrotethe?rstmonograph onthesubject, The Kinematics of Vorticity(1954);andasalsoevidencedby the appearance of several books on this ?eld in 1990s. The present book is characterizedbythefollowingfeatures: 1. A basic physical guide throughout the book. The material is directed by a basic observation on the splitting and coupling of two fundamental processes in ?uid motion, i.e., shearing (unique to ?uid) and compre- ing/expanding.Thevorticityplaysakeyroleintheformer,andavortex isnothingbuta?uidbodywithhighconcentrationofvorticitycompared to its surrounding ?uid. Thus, the vorticity and vortex dynamics is - cordinglyde?nedasthetheoryofshearingprocessanditscouplingwith compressing/expandingprocess. 2. A description of the vortex evolution following its entire life.Thisbegins from the generation of vorticity to the formation of thi...

  16. Blood pressure and left ventricular mass in subjects with type 2 diabetes and gingivitis or chronic periodontitis.

    Science.gov (United States)

    Franek, Edward; Napora, Magdalena; Blach, Anna; Budlewski, Tadeusz; Gozdowski, Dariusz; Jedynasty, Krystyna; Krajewski, Jarosław; Gorska, Renata

    2010-10-01

    This study aimed to answer the question of whether chronic periodontitis in subjects with type 2 diabetes mellitus is associated with increased left ventricular mass (LVM) and systemic and central blood pressure (CBP). One hundred and fifty-five subjects with type 2 diabetes (67 F, 88 M, mean age 61.1±6.9 years, BMI 32.7±5.7 kg/m(2)) were divided according to their periodontal status into biofilm-gingival interface - healthy (BGI-H, 14 subjects), BGI-gingivitis (BGI-G, 119 subjects) and BGI-periodontitis (BGI-P, 22 subjects) groups. In all subjects, LVM, systemic and CBP were measured. The LVM index (LVMI) was calculated. (1) BGI-P and BGI-G subjects, respectively, had higher (mean; 95% CI) LVM (238.6 g; 206.6-267.4 and 222.8 g; 207.0-238.2) versus BGI-H subjects (170.3 g; 125.5-217.8).
(2) BGI-P and BGI-G subjects, respectively, had higher (mean; 95% CI) LVM1 (95.2 g/m(2) ; 82.9-107.4) and 87.8 g/m(2) ; 81.5-94.1) versus BGI-H subjects (63.7 g/m(2) ; 45.2-62.3).
(3) BGI-P subjects had higher central and systemic systolic and diastolic blood pressure than subjects from BGI-G and BGI-H groups. In subjects with type 2 diabetes, periodontitis and gingivitis are associated with increased LVM and periodontitis is associated with increased central and systemic blood pressure. © 2010 John Wiley & Sons A/S.

  17. Vortices at Microwave Frequencies

    Science.gov (United States)

    Silva, Enrico; Pompeo, Nicola; Dobrovolskiy, Oleksandr V.

    2017-11-01

    The behavior of vortices at microwave frequencies is an extremely useful source of information on the microscopic parameters that enter the description of the vortex dynamics. This feature has acquired particular relevance since the discovery of unusual superconductors, such as cuprates. Microwave investigation then extended its field of application to many families of superconductors, including the artificially nanostructured materials. It is then important to understand the basics of the physics of vortices moving at high frequency, as well as to understand what information the experiments can yield (and what they can not). The aim of this brief review is to introduce the readers to some basic aspects of the physics of vortices under a microwave electromagnetic field, and to guide them to an understanding of the experiment, also by means of the illustration of some relevant results.

  18. Effects of nicardipine on coronary blood flow, left ventricular inotropic state and myocardial metabolism in patients with angina pectoris.

    Science.gov (United States)

    Rousseau, M F; Vincent, M F; Cheron, P; van den Berghe, G; Charlier, A A; Pouleur, H

    1985-01-01

    The effects of intravenous nicardipine (2.5 mg) on the left ventricular (LV) inotropic state, LV metabolism, and coronary haemodynamics were analysed in 22 patients with angina pectoris. Measurements were made at fixed heart rate (atrial pacing), under basal state, and during a cold pressor test. After nicardipine, coronary blood flow and oxygen content in the coronary sinus increased significantly. The indices of inotropic state increased slightly, and the rate of isovolumic LV pressure fall improved. Myocardial oxygen consumption was unchanged despite the significant reduction in pressure-rate product, but LV lactate uptake increased, particularly during the cold pressor test. When nicardipine was administered after propranolol, the indices of inotropic state were unaffected. The lack of direct effect of nicardipine on LV inotropic state was further confirmed by intracoronary injection of 0.1 and 0.2 mg in a separate group of 10 patients. It is concluded that the nicardipine-induced coronary dilatation seems to improve perfusion and aerobic metabolism in areas with chronic ischaemia, resulting in reduced lactate production and augmented oxygen consumption.

  19. VENTRICULAR RATE AND BLOOD PRESSURE ORTHOSTATIC REACTIONS IN PATIENTS WITH PERMANENT ATRIAL FIBRILLATION IN GENERAL CARDIOVASCULAR RISK GROUPS

    Directory of Open Access Journals (Sweden)

    L. O. Martymianova

    2016-12-01

    Full Text Available Types and prevalence of ventricular rate (VR, systolic (SBP and diastolic (DBP blood pressure (BP orthostatic reactions (OR in patients with permanent atrial fibrillation (AF in general cardiovascular risk groups (GCVR were studied in 137 patients (73 men and 64 women, aged 66.4 ± 9.9 years. VR was measured by the electrocardiography (ECG on the computer electrocardiograph «CardioLab 2000» and BP – semi-automatic tonometer Microlife BP2BIO. Changes VR, SBP and DBP in the range of ± 5 % were classified as a lack, an increase of 5 % and more – both positive and decreased by 5 % or more – as a negative OR. GCVR calculated in accordance with the scale of SCORE. Patients were classified into groups of GCVR. Statistical evaluation of the results was performed with the parametric estimate of the mean (M and standard deviation (sd and non-parametric Student's T-test and Mann-Whitney test methods. It was found that patients with AF have all three types (positive, absent, negative OR of VR, SBP and DBP, which are stored in all classes GCVR. Optimizing the management of patients with atrial fibrillation, including with and through modification within the GCVR risk factors should take into account deviations in orthostatic reactions of VR, SBP and DBP.

  20. Theory of Concentrated Vortices

    DEFF Research Database (Denmark)

    Alekseenko, Sergey; Kuibin, Pavel; Okulov, Valery

    This book presents comprehensive and authoritative coverage of the wide field of concentrated vortices observed in nature and technique. The methods for research of their kinematics and dynamics are considered. Special attention is paid to the flows with helical symmetry. The authors have describ...... models of vortex structures used for interpretation of experimental data which serve as a ground for development of theoretical and numerical approaches to vortex investigation. Achievements in the fields of stability analysis, waves on vortices and vortex breakdown are also presented....

  1. The relationship between blood pressure and left ventricular mass index depends on an excess adiposity.

    Science.gov (United States)

    Norton, Gavin R; Majane, Olebogeng Hi; Libhaber, Elena; Maseko, Muzi J; Makaula, Siyanda; Libhaber, Carlos; Woodiwiss, Angela J

    2009-09-01

    To determine whether blood pressure (BP)-LVM relationships depend in-part on the influence of an excess adiposity and whether this translates into a greater effect of hypertension on LVM in obese as compared with lean people. In 399 randomly recruited participants from a general population with a high prevalence of excess adiposity ( approximately 68%), we assessed whether the relationships between conventional blood pressure (BP) and LVM indexed for height (LVMI) (determined from echocardiography) are influenced by adiposity. We confirmed these outcomes using 24-h ambulatory measurements in 297 participants; and carotid-femoral pulse wave velocity (PWV) (applanation tonometry) in 328 participants and from plasma leptin concentrations, we assessed whether leptin could mediate this effect. After adjustments for appropriate confounders, including the individual terms for adiposity and BP, interactions between adiposity indices (either waist circumference or the mean of subscapular and triceps skin-fold thickness) and either conventional systolic BP (SBP), 24-h SBP, PWV, conventional pulse pressure (PP), or 24-h PP were independently associated with LVMI (P obese as compared with lean participants. Every one SD increase in conventional SBP ( approximately 22 mmHg) was associated with a 1.61 g/m increase in LVMI in participants with a normal waist circumference, in comparison to a 5.24 g/m increase in LVMI in those with an increased waist circumference (P obesity (LVMI, normotensives = 45.6 g/m, hypertensives = 51.0 g/m, P obese, but not in lean people in groups of African descent in South Africa.

  2. Progress in the development of a transcutaneously powered axial flow blood pump ventricular assist system.

    Science.gov (United States)

    Parnis, S M; Conger, J L; Fuqua, J M; Jarvik, R K; Inman, R W; Tamez, D; Macris, M P; Moore, S; Jacobs, G; Sweeney, M J; Frazier, O H

    1997-01-01

    Development of the Jarvik 2000 intraventricular assist system for long-term support is ongoing. The system integrates the Jarvik 2000 axial flow blood pump with a microprocessor based automatic motor controller to provide response to physiologic demands. Nine devices have been evaluated in vivo (six completed, three ongoing) with durations in excess of 26 weeks. Instrumented experiments include implanted transit-time ultrasonic flow probes and dual micromanometer LV/AoP catheters. Treadmill exercise and heart pacing studies are performed to evaluate control system response to increased heart rates. Pharmacologically induced cardiac dysfunction studies are performed in awake and anesthetized calves to demonstrate control response to simulated heart failure conditions. No deleterious effects or events were encountered during any physiologic studies. No hematologic, renal, hepatic, or pulmonary complications have been encountered in any study. Plasma free hemoglobin levels of 7.0 +/- 5.1 mg/dl demonstrate no device related hemolysis throughout the duration of all studies. Pathologic analysis at explant showed no evidence of thromboembolic events. All pump surfaces were free of thrombus except for a minimal ring of fibrin, (approximately 1 mm) on the inflow bearing. Future developments for permanent implantation will include implanted physiologic control systems, implanted batteries, and transcutaneous energy and data transmission systems.

  3. Vortices and Jacobian varieties

    DEFF Research Database (Denmark)

    Manton, Nicholas S.; M. Romão, Nuno

    2011-01-01

    We investigate the geometry of the moduli space of N-vortices on line bundles over a closed Riemann surface of genus g > 1, in the little explored situation where 1 = 1, the vortex metric typically degenerates as the dissolving limit is approached, the degeneration occurring precisely on the crit...

  4. Relativistic Electron Vortices.

    Science.gov (United States)

    Barnett, Stephen M

    2017-03-17

    The desire to push recent experiments on electron vortices to higher energies leads to some theoretical difficulties. In particular the simple and very successful picture of phase vortices of vortex charge ℓ associated with ℓℏ units of orbital angular momentum per electron is challenged by the facts that (i) the spin and orbital angular momentum are not separately conserved for a Dirac electron, which suggests that the existence of a spin-orbit coupling will complicate matters, and (ii) that the velocity of a Dirac electron is not simply the gradient of a phase as it is in the Schrödinger theory suggesting that, perhaps, electron vortices might not exist at a fundamental level. We resolve these difficulties by showing that electron vortices do indeed exist in the relativistic theory and show that the charge of such a vortex is simply related to a conserved orbital part of the total angular momentum, closely related to the familiar situation for the orbital angular momentum of a photon.

  5. Left Ventricular Geometry Determines Prognosis and Reverse J-Shaped Relation Between Blood Pressure and Mortality in Ischemic Stroke Patients.

    Science.gov (United States)

    Park, Chan Soon; Park, Jun-Bean; Kim, Yerim; Yoon, Yeonyee E; Lee, Seung-Pyo; Kim, Hyung-Kwan; Kim, Yong-Jin; Cho, Goo-Yeong; Sohn, Dae-Won; Lee, Seung-Hoon

    2017-06-09

    This study sought to investigate the prognostic significance of left ventricular (LV) mass and geometry in ischemic stroke survivors, as well as the LV geometry-specific differences in the blood pressure-mortality relationship. LV mass and geometry are well-known prognostic factors in various populations; however, there are no data on their role in ischemic stroke patients. We prospectively recruited 2,328 consecutive patients admitted with acute ischemic stroke to our institute between 2002 and 2010. Of these, 2,069 patients were analyzed in whom echocardiographic data were available to assess LV mass and geometry. All-cause mortality was significantly greater in patients with concentric hypertrophy (adjusted hazard ratio [HR]: 1.417; 95% confidence interval [CI]: 1.045 to 1.920) and concentric remodeling (HR: 1.540; 95% CI: 1.115 to 2.127) but nonsignificantly in those with eccentric hypertrophy (HR: 1.388; 95% CI: 0.996 to 1.935) compared with normal geometry in multivariate analyses. Relative wall thickness was a significant predictor of all-cause mortality (HR: 1.149 per 0.1-U increase in relative wall thickness; 95% CI: 1.021 to 1.307), whereas LV mass index was not (HR: 1.003 per 1 g/m2 increase in LV mass index; 95% CI: 0.999 to 1.007). Similar results were observed with cardiovascular mortality. In multivariable fractional polynomials, patients with altered LV geometry showed reverse J-curve relationships between acute-phase systolic blood pressure and all-cause or cardiovascular mortality, with the highest risks in the lower extremes, whereas those with normal geometry did not. Echocardiographic assessment of LV geometry provided independent and additive prognostic information in ischemic stroke patients. A reverse J-shaped relation of mortality with blood pressure was found in patients with abnormal LV geometry. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  6. Left Ventricular Hypertrophy

    Science.gov (United States)

    ... need to restrict certain physical activities, such as weightlifting, which may temporarily raise your blood pressure. The ... Accessed April 6, 2015. Chatterjee S, et al. Meta-analysis of left ventricular hypertrophy and sustained arrhythmias. American ...

  7. The effect of nondipping blood pressure patterns on cardiac structural changes and left ventricular diastolic functions in normotensives.

    Science.gov (United States)

    Soylu, Ahmet; Duzenli, Mehmet Akif; Yazici, Mehmet; Ozdemir, Kurtulus; Tokac, Mehmet; Gok, Hasan

    2009-04-01

    Cardiac structural changes have been reported to be more prominent in nondipper normotensives than the dipper ones. But the influence of nondipping status on cardiac diastolic functions of normotensives has not been studied yet. In this study, we investigated the effect of nondipping status on both cardiac structural changes and left ventricular (LV) diastolic functions in normotensives. We performed ambulatory blood pressure (BP) monitoring (ABPM) and echocardiography in 62 normotensive subjects with the following criteria: (1) office BP < 140/90 mmHg; (2) average 24-hour ambulatory BP < 130/80 mmHg. In the evaluation by tissue Doppler imaging (TDI), the early diastolic myocardial peak velocity (Em) and Em/late diastolic myocardial peak velocity (Am) ratio (Em/Am ratio) were lower in nondippers than those in dippers (P = 0.009 and P < 0.001, respectively). Isovolumic relaxation time (IRT) and myocardial performance index (MPI) were higher in nondippers than those in dippers (P = 0.036 and P = 0.026, respectively). Nondipping status, independent of other factors, was observed to cause both a decrease in the Em and Em/Am ratio and an increase in IRT. However, its effect on IRT was not statistically significant (coefficient =-0.27, P = 0.027; coefficient =-0.37, P = 0.002; coefficient = 0.20, P = 0.082, respectively). Nondipping of nocturnal BP seems to be a determinant of cardiac remodeling and LV diastolic dysfunction (LVDD) and may result in a cardiovascular (CV) risk independent of the increase in LV mass (LVM) in normotensives.

  8. Office and Home Blood Pressures as Determinants of Electrocardiographic Left Ventricular Hypertrophy Among Black Nigerians Compared With White Flemish.

    Science.gov (United States)

    Odili, Augustine N; Thijs, Lutgarde; Yang, Wen-Yi; Ogedengbe, John O; Nwegbu, Maxwell M; Jacobs, Lotte; Wei, Fang-Fei; Feng, Ying-Mei; Zhang, Zhen-Yu; Kuznetsova, Tatiana; Nawrot, Tim S; Staessen, Jan A

    2017-11-01

    The association of electrocardiographic left ventricular hypertrophy (ECG-LVH) with blood pressure (BP) in Blacks living in sub-Saharan Africa remains poorly documented. In 225 Black Nigerians and 729 White Flemish, we analyzed QRS voltages and voltage-duration products and 12 criteria diagnostic of ECG-LVH in relation to office BP (mean of 5 consecutive readings) and home BP (duplicate morning and evening readings averaged over 1 week). In multivariable analyses, QRS voltage and voltage-duration indexes were generally higher in Blacks than Whites. By using any of 12 criteria, ECG-LVH was more prevalent among Black than White men (54.4% vs. 36.0%) with no ethnic difference among women (17.1%). Precordial voltages and voltage-duration products increased with office and home systolic BP (SBP), and increases were up to 3-fold steeper in Blacks. In Blacks vs. Whites, increases in the Sokolow-Lyon voltage associated with a 10-mm Hg higher SBP were 0.18 mV (95% confidence interval [CI], 0.09-0.26) vs. 0.06 mV (0.02-0.09) and 0.17 mV (0.07-0.28) vs. 0.11 mV (CI, 0.07-0.15) for office and home BP, respectively, with a significant ethnic gradient (P office and home BP in Blacks than Whites. Associations of ECG voltages and voltage-duration products and risk of ECG-LVH with BP are steeper in Black Nigerians compared with a White reference population. In resource-poor settings of sub-Saharan Africa, the ECG in combination with office and home BP is an essential instrument in risk stratification across the entire BP range.

  9. Vasopressin V2 receptor antagonist tolvaptan is effective in heart failure patients with reduced left ventricular systolic function and low blood pressure.

    Science.gov (United States)

    Suzuki, Satoshi; Yoshihisa, Akiomi; Yamaki, Takayoshi; Sugimoto, Koichi; Kunii, Hiroyuki; Nakazato, Kazuhiko; Abe, Yukihiko; Saito, Tomiyoshi; Ohwada, Takayuki; Suzuki, Hitoshi; Saitoh, Shu-ichi; Kubota, Isao; Takeishi, Yasuchika

    2015-01-01

    Diuresis is a major therapy for the reduction of congestive symptoms in acute decompensated heart failure (ADHF) patients. Carperitide has natriuretic and vasodilatory effects, and tolvaptan produces water excretion without electrolyte excretion. We previously reported the usefulness of tolvaptan compared to carperitide in ADHF patients with fluid volume retention. The purpose of this study was to examine whether the efficacy of tolvaptan was altered in ADHF patients with reduced left ventricular systolic function and in those with hypotension. A total of 109 hospitalized ADHF patients were randomly assigned to either a tolvaptan or a carperitide treatment group. Baseline clinical characteristics were not different between the two groups. We divided these patients based on the left ventricular ejection fraction (EF) by echocardiography, and blood pressure (BP) at the time of admission. Daily urine volume between the tolvaptan and carperitide groups in patients with preserved EF (≥ 50%) was not different, however, in those with reduced EF (tolvaptan group than in the carperitide group (day 2, 3, 4, P tolvaptan group than in the carperitide group (day 1, P = 0.021; day 3, P = 0.017) in the low blood pressure group (BP tolvaptan is more effective than carperitide, especially in ADHF patients with reduced left ventricular systolic function and without hypertension.

  10. Vortices and nanostructured superconductors

    CERN Document Server

    2017-01-01

    This book provides expert coverage of modern and novel aspects of the study of vortex matter, dynamics, and pinning in nanostructured and multi-component superconductors. Vortex matter in superconducting materials is a field of enormous beauty and intellectual challenge, which began with the theoretical prediction of vortices by A. Abrikosov (Nobel Laureate). Vortices, vortex dynamics, and pinning are key features in many of today’s human endeavors: from the huge superconducting accelerating magnets and detectors at the Large Hadron Collider at CERN, which opened new windows of knowledge on the universe, to the tiny superconducting transceivers using Rapid Single Flux Quanta, which have opened a revolutionary means of communication. In recent years, two new features have added to the intrinsic beauty and complexity of the subject: nanostructured/nanoengineered superconductors, and the discovery of a range of new materials showing multi-component (multi-gap) superconductivity. In this book, leading researche...

  11. 4D left ventricular resultant wall motion and blood flow assessed by phase-shift velocity mapping at high-field 3T MRI.

    Science.gov (United States)

    Samnøy, Stig F; Cuypers, Jochem; Greve, Gottfried; Larsen, Terje H

    2017-11-01

    Contractility and elasticity of the myocardium are important variables for detecting anomalies that may influence pump function. It is important to assess both wall motion and blood flow to detect regional left ventricular (LV) dysfunction and abnormal flow patterns. This study discusses four-dimensional (4D) phase-contrast magnetic resonance imaging (MRI) for simultaneous quantification and visualization of LV wall motion and blood flow. In thirteen healthy subjects, a three-directional retrospective cardiac triggered phase-shift velocity mapping technique was used to acquire velocity data of the LV throughout the cardiac cycle. All short-axis slices of the LV wall were segmented in six sectors of 60° starting from the anterior hinge point between the right and left ventricles, from base to apex. Velocity data in resultant, radial, circumferential and longitudinal directions were calculated and presented as coloured three-directional vectors. Our findings showed a reduction in maximum wall velocities from base to apex, whereas for the radial and circumferential directions no significant differences were noted (13·1 ± 2·7 and 13·0 ± 2·9 cm s(-1) , respectively. P = 0·9). The longitudinal maximum velocities (21·0 ± 0·6 cm s(-1) ) were significantly higher than the radial and circumferential components (P = 0·002). We found that the inclination angle of the resultant blood flow was changed towards the left ventricular outflow tract during systole. Using this 4D MRI velocity mapping technique, we present an improved method for quantification and visualization of ventricular wall velocities in the radial, circumferential and longitudinal directions, as well as for the intracavity blood flow. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  12. Cardiovascular devices; reclassification of nonroller-type cardiopulmonary bypass blood pumps for cardiopulmonary and circulatory bypass; effective date of requirement for premarket approval for nonroller-type cardiopulmonary bypass blood pumps for temporary ventricular support. Final order.

    Science.gov (United States)

    2015-06-08

    The Food and Drug Administration (FDA) is issuing a final order to reclassify nonroller-type cardiopulmonary bypass blood pump (NRP) devices for cardiopulmonary and circulatory bypass, a preamendments class III device, into class II (special controls), and to require the filing of a premarket approval application (PMA) for NRP devices for temporary ventricular support. FDA is also revising the title and identification of the regulation for NRP devices in this order.

  13. Vorticity dynamics in an intracranial aneurysm

    Science.gov (United States)

    Le, Trung; Borazjani, Iman; Sotiropoulos, Fotis

    2008-11-01

    Direct Numerical Simulation is carried out to investigate the vortex dynamics of physiologic pulsatile flow in an intracranial aneurysm. The numerical solver is based on the CURVIB (curvilinear grid/immersed boundary method) approach developed by Ge and Sotiropoulos, J. Comp. Physics, 225 (2007) and is applied to simulate the blood flow in a grid with 8 million grid nodes. The aneurysm geometry is extracted from MRI images from common carotid artery (CCA) of a rabbit (courtesy Dr.Kallmes, Mayo Clinic). The simulation reveals the formation of a strong vortex ring at the proximal end during accelerated flow phase. The vortical structure advances toward the aneurysm dome forming a distinct inclined circular ring that connects with the proximal wall via two long streamwise vortical structures. During the reverse flow phase, the back flow results to the formation of another ring at the distal end that advances in the opposite direction toward the proximal end and interacts with the vortical structures that were created during the accelerated phase. The basic vortex formation mechanism is similar to that observed by Webster and Longmire (1998) for pulsed flow through inclined nozzles. The similarities between the two flows will be discussed and the vorticity dynamics of an aneurysm and inclined nozzle flows will be analyzed.This work was supported in part by the University of Minnesota Supercomputing Institute.

  14. Effect of loading-dose ticagrelor on coronary blood flow, left ventricular remodeling and myocardial enzyme spectrum in patients with acute myocardial infarction after interventional therapy

    Directory of Open Access Journals (Sweden)

    Xiao-Rui Xie

    2016-12-01

    Full Text Available Objective: To study the effect of loading-dose ticagrelor on coronary blood flow, left ventricular remodeling and myocardial enzyme spectrum in patients with acute myocardial infarction after interventional therapy. Methods: A total of 86 patients with acute myocardial infarction who received emergency PCI in our hospital between May 2013 and May 2016 were selected and randomly divided into two groups, ticagrelor group received perioperative ticagrelor therapy and clopidogrel group received perioperative clopidogrel therapy. After PCI, coronary blood flow reperfusion was evaluated, serum myocardial remodeling indexes and myocardial enzymes were determined, and cardiac color Doppler ultrasonography was conducted to determine the cardiac function indexes. Results: TIMI grading and TMPG grading of ticagrelor group after PCI were significantly higher than those of clopidogrel group; serum MMP9, BNP, CITP, PICP, PIIINP, CK, CK-MB, cTnI and cTnT content of ticagrelor group 24h after operation were significantly lower than those of clopidogrel group; LVEDD, LVSED and LVMI of ticagrelor group 2 weeks after operation were significantly lower than those of clopidogrel group while LVEF was significantly higher than that of clopidogrel group. Conclusion: Peri-PCI loading-dose ticagrelor can improve coronary blood perfusion and reduce ventricular remodeling and myocardial injury in patients with acute myocardial infarction.

  15. Dynamics of nonstationary dipole vortices

    DEFF Research Database (Denmark)

    Hesthaven, J.S.; Lynov, Jens-Peter; Nycander, J.

    1993-01-01

    The dynamics of tilted dipole vortices in the equivalent barotropic vorticity (or Hasegawa-Mima) equation is studied. A recent theory is compared with numerical simulations and found to describe the short time behavior of dipole vortices well. In the long time limit the dipoles are found to either...... disintegrate or relax toward a steady eastward propagating dipole vortex. This relaxation is a consequence of nonviscous enstrophy loss by the dipole vortex....

  16. Experimental study on the effect of an artificial cardiac valve on the left ventricular flow

    Science.gov (United States)

    Wang, JiangSheng; Gao, Qi; Wei, RunJie; Wang, JinJun

    2017-09-01

    The use of artificial valves to replace diseased human heart valves is currently the main solution to address the malfunctioning of these valves. However, the effect of artificial valves on the ventricular flow still needs to be understood in flow physics. The left ventricular flow downstream of a St. Jude Medical (SJM) bileaflet mechanical heart valve (BMHV), which is a widely implanted mechanical bileaflet valve, is investigated with time-resolved particle image velocimetry in the current work. A tilting-disk valve is installed on the aortic orifice to guarantee unidirectional flow. Several post-processing tools are applied to provide combined analyses of the physics involved in the ventricular flow. The triple jet pattern that is closely related to the characteristics of the bileaflet valve is discussed in detail from both Eulerian and Lagrangian views. The effects of large-scale vortices on the transportation of blood are revealed by the combined analysis of the tracking of Lagrangian coherent structures, the Eulerian monitoring of the shear stresses, and virtual dye visualization. It is found that the utilization of the SJM BMHV complicates the ventricular flow and could reduce the efficiency of blood transportation. In addition, the kinematics of the bileaflets is presented to explore the effects of flow structures on their motion. These combined analyses could elucidate the properties of SJM BMHV. Furthermore, they could provide new insights into the understanding of other complex blood flows.

  17. Ginzburg-Landau vortices

    CERN Document Server

    Bethuel, Fabrice; Helein, Frederic

    2017-01-01

    This book is concerned with the study in two dimensions of stationary solutions of uɛ of a complex valued Ginzburg-Landau equation involving a small parameter ɛ. Such problems are related to questions occurring in physics, e.g., phase transition phenomena in superconductors and superfluids. The parameter ɛ has a dimension of a length which is usually small.  Thus, it is of great interest to study the asymptotics as ɛ tends to zero. One of the main results asserts that the limit u-star of minimizers uɛ exists. Moreover, u-star is smooth except at a finite number of points called defects or vortices in physics. The number of these defects is exactly the Brouwer degree – or winding number – of the boundary condition. Each singularity has degree one – or as physicists would say, vortices are quantized. The singularities have infinite energy, but after removing the core energy we are lead to a concept of finite renormalized energy.  The location of the singularities is completely determined by minimiz...

  18. Identification of differentially expressed transcripts and pathways in blood one week and six months following implant of left ventricular assist devices.

    Directory of Open Access Journals (Sweden)

    Adam Mitchell

    Full Text Available INTRODUCTION: Continuous-flow left ventricular assist devices (LVADs are an established therapy for patients with end-stage heart failure. The short- and long-term impact of these devices on peripheral blood gene expression has not been characterized, and may provide insight into the molecular pathways mediated in response to left ventricular remodeling and an improvement in overall systemic circulation. We performed RNA sequencing to identify genes and pathways influenced by these devices. METHODS: RNA was extracted from blood of 9 heart failure patients (8 male prior to LVAD implantation, and at 7 and 180 days postoperatively. Libraries were sequenced on an Illumina HiSeq2000 and sequences mapped to the human Ensembl GRCh37.67 genome assembly. RESULTS: A specific set of genes involved in regulating cellular immune response, antigen presentation, and T cell activation and survival were down-regulated 7 days after LVAD placement. 6 months following LVAD placement, the expression levels of these genes were significantly increased; yet importantly, remained significantly lower than age and sex-matched samples from healthy controls. CONCLUSIONS: In summary, this genomic analysis identified a significant decrease in the expression of genes that promote a healthy immune response in patients with heart failure that was partially restored 6 months following LVAD implant.

  19. Regular cocaine use is associated with increased systolic blood pressure, aortic stiffness and left ventricular mass in young otherwise healthy individuals.

    Directory of Open Access Journals (Sweden)

    Rebecca Kozor

    Full Text Available BACKGROUND: The cardiovascular impact of cocaine use in otherwise healthy individuals who consider themselves 'social' users is not well established. METHODS/RESULTS: Twenty regular cocaine users and 20 control subjects were recruited by word-of-mouth. Cardiovascular magnetic resonance was performed to assess cardiac and vascular structure and function. Cocaine users had higher systolic blood pressure compared to non-users (134±11 vs 126±11 mmHg, p = 0.036, a finding independent of age, body surface area, smoking and alcohol consumption. Cocaine use was associated with increased arterial stiffness - reflected by reduced aortic compliance (1.3±0.2 vs 1.7±0.5 cm2×10-2.mmHg-1, p = 0.004, decreased distensibility (3.8±0.9 vs 5.1±1.4 mmHg-1.10-3, p = 0.001, increased stiffness index (2.6±0.6 vs 2.1±0.6, p = 0.005, and higher pulse wave velocity (5.1±0.6 vs 4.4±0.6 m.s-1, p = 0.001. This change in aortic stiffness was independent of vessel wall thickness. Left ventricular mass was 18% higher in cocaine users (124±25 vs 105±16 g, p = 0.01, a finding that was independent of body surface area, and left atrial diameter was larger in the user group than controls (3.8±0.6 vs 3.5±0.3 cm, p = 0.04. The increased left ventricular mass, systolic blood pressure and vascular stiffness measures were all associated with duration and/or frequency of cocaine use. No late gadolinium enhancement or segmental wall motion abnormalities were seen in any of the subjects. CONCLUSIONS: Compared with the non-user control cohort, cocaine users had increased aortic stiffness and systolic blood pressure, associated with greater left ventricular mass. These measures are all well known risk factors for premature cardiovascular events, highlighting the dangers of cocaine use, even in a 'social' setting, and have important public health implications.

  20. Usefulness of gated blood-pool SPECT for the diagnosis of right ventricular dysplasia; Apport de la tomo-ventriculographie isotopique dans le diagnostic de la dysplasie arythmogene du ventricule droit

    Energy Technology Data Exchange (ETDEWEB)

    Dechaux, L.; Rossi, M.; Mariano-Goulard, D. [Centre Hospitalier Universitaire Lapeyronie, Service Central de Medecine Nucleaire, 34 - Montpellier (France); Rouzet, F.; Le Guludec, D. [Centre Hospitalier Universitaire Bichat, Service de Medecine Nucleaire, 75 - Paris (France)

    2006-05-15

    Arhythmogenic right ventricular dysplasia (ARVD) is a severe cardiomyopathy that is an important cause of sudden death in young patients. Diagnosis of ARVD is often a challenge because conventional imaging modalities as conventional angiography and echocardiography have significant limitations to visualize the right ventricle (RV) and to evaluate right ventricular abnormalities. The aim of this study was to evaluate the interest of the assessment of RV functional parameters by gated blood pool SPECT (GBPS) in the diagnostic of ARVD. 22 patients with an old ARVC and 23 healthy people underwent gated blood pool SPECT. We compare right ventricular (RV) volumes and right ventricular ejection fractions (RVEF) with two soft-wares: an automatic software QBS, and a semi-automatic software Tompool. With both softwares, RV volumes was significantly increased (p=0.01) and RVEF was decreased in patients with AR VC (p=0.01). Tompool can also evaluate local ventricular parameters and showed an abnormal and heterogeneous distribution of times of end systole for the right ventricle in patients with AR VC. Areas under the ROC curve tends to be higher with Tompool than with QBS but there was no statistically significant difference and a complementary study with recent ARVC is necessary to confirm this trend. Gated blood SPECT is interesting and could be generalized in ARVD. (author)

  1. Long-Term Excessive Body Weight and Adult Left Ventricular Hypertrophy Are Linked Through Later-Life Body Size and Blood Pressure: The Bogalusa Heart Study.

    Science.gov (United States)

    Zhang, Huijie; Zhang, Tao; Li, Shengxu; Guo, Yajun; Shen, Wei; Fernandez, Camilo; Harville, Emily; Bazzano, Lydia A; Urbina, Elaine M; He, Jiang; Chen, Wei

    2017-05-12

    Childhood adiposity is associated with cardiac structure in later life, but little is known regarding to what extent childhood body weight affects adult left ventricular geometric patterns through adult body size and blood pressure (BP). Determine quantitatively the mediation effect of adult body weight and BP on the association of childhood body mass index (BMI) with adult left ventricular (LV) hypertrophy. This longitudinal study consisted of 710 adults, aged 26 to 48 years, who had been examined for BMI and BP measured ≥4× during childhood and ≥2× during adulthood, with a mean follow-up period of 28.0 years. After adjusting for age, race, and sex, adult BMI had a significant mediation effect (76.4%; Padult LV mass index association. The mediation effects of adult systolic BP (15.2%), long-term burden (12.1%), and increasing trends of systolic BP (7.9%) were all significant (Padult LV hypertrophy, eccentric hypertrophy, and concentric hypertrophy. Importantly, the mediation effects of adult BMI were all significantly stronger than those of adult systolic BP on LV mass index, LV hypertrophy, and LV remodeling patterns (Padult cardiac structure, and early life excessive body weight and adult LV hypertrophy are linked through later life excessive body weight and elevated BP. © 2017 American Heart Association, Inc.

  2. Effects of candesartan versus amlodipine on home-measured blood pressure, QT dispersion and left ventricular hypertrophy in high-risk hypertensive patients.

    Science.gov (United States)

    Matsuno, Yasunari; Minatoguchi, Shinya; Fujiwara, Hisayoshi

    2011-04-01

    The GIFU substudy of the Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) trial was conducted to compare the long-term effects of candesartan and amlodipine on office- and home-measured blood pressure (BP), QTc dispersion and left ventricular mass index (LVMI) in high-risk Japanese patients with hypertension. We used a prospective, randomized, open-label design with blinded assessment of endpoints. Patients were assigned to candesartan-based therapy up to 12 mg/day (n = 100) or amlodipine-based therapy up to 10 mg/day (n = 101) and followed for 3 years. LVMI was assessed by echocardiography and QTc dispersion was obtained from electrocardiograms. Both candesartan and amlodipine lowered and controlled office- and home-measured BP levels with no significant between-treatment differences. In patients diagnosed with left ventricular hypertrophy (LVH) at baseline, both candesartan and amlodipine significantly regressed LVMI after 3 years. However, candesartan (41.7 ± 15.1 ms at baseline vs 32.9 ± 16.6 ms after 3 years, p candesartan effect will translate into improved prognosis in terms of cardiovascular mortality and morbidity.

  3. Cardiac output and blood flow redistribution in fetuses with D-loop transposition of the great arteries and intact ventricular septum: insights into pathophysiology.

    Science.gov (United States)

    Godfrey, M E; Friedman, K G; Drogosz, M; Rudolph, A M; Tworetzky, W

    2017-11-01

    Although the postnatal physiology of D-loop transposition of the great arteries with intact ventricular septum (D-TGA/IVS) is well established, little is known about fetal D-TGA/IVS. In the normal fetus, the pulmonary valve (PV) is larger than the aortic valve (AoV), there is exclusive right-to-left flow at the foramen ovale (FO) and ductus arteriosus (DA), and the left ventricle (LV) ejects 40% of combined ventricular output (CVO) through the aorta, primarily to the brain. In D-TGA/IVS, the LV ejects oxygen-rich blood to the pulmonary artery, theoretically leading to pulmonary vasodilation, increased branch pulmonary artery flow and reduced DA flow. In this study, we tested the hypothesis that D-TGA/IVS anatomy results in altered cardiac valve sizes, ventricular contribution to CVO, and FO and DA flow direction. Seventy-four fetuses with D-TGA/IVS that underwent fetal echocardiography at our institution between 2004 and 2015 were included in the study. AoV, PV, mitral valve and tricuspid valve sizes were measured and Z-scores indexed to gestational age were generated. Ventricular output was calculated using Doppler-derived velocity-time integral, and direction of flow at the FO and DA shunts was recorded in each fetus using both color Doppler and flap direction. Measurements in the D-TGA/IVS fetuses were compared with data of 222 controls, matched for gestational-age range, from our institutional normal fetal database. The LV component of CVO was higher in D-TGA/IVS fetuses than in controls (50.7% vs 40.2%; P theory that high pulmonary artery oxygen content reduces pulmonary vascular resistance, thereby increasing branch pulmonary artery flow and venous return, which results in increased LV preload and output. Pulmonary sensitivity to oxygen is thought to increase later in gestation, which may explain the higher incidence of bidirectional shunting. Consequences of these flow alterations include increased aortic and, most likely, brain flow, perhaps in an attempt

  4. Primordial vorticity and gradient expansion

    CERN Document Server

    Giovannini, Massimo

    2012-01-01

    The evolution equations of the vorticities of the electrons, ions and photons in a pre-decoupling plasma are derived, in a fully inhomogeneous geometry, by combining the general relativistic gradient expansion and the drift approximation within the Adler-Misner-Deser decomposition. The vorticity transfer between the different species is discussed in this novel framework and a set of general conservation laws, connecting the vorticities of the three-component plasma with the magnetic field intensity, is derived. After demonstrating that a source of large-scale vorticity resides in the spatial gradients of the geometry and of the electromagnetic sources, the total vorticity is estimated to lowest order in the spatial gradients and by enforcing the validity of the momentum constraint. By acknowledging the current bounds on the tensor to scalar ratio in the (minimal) tensor extension of the $\\Lambda$CDM paradigm the maximal comoving magnetic field induced by the total vorticity turns out to be, at most, of the or...

  5. Correlation between left ventricular diastolic function before and after valve replacement surgery and myocardial ultrastructural changes in patients with left ventricular volume-overloaded valvular heart diseases; Evaluation with gated blood pool scintigraphy using [sup 99m]Tc

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Tomiro (Okayama Univ. (Japan). School of Medicine)

    1993-06-01

    Left ventricular (LV) diastolic functions in 23 patients with aortic regurgitation (AR) and 22 patients with mitral regurgitation (MR) were evaluated by gated blood pool scintigraphy. LV myocardial biopsy was performed during open heart surgery, and LV myocardial ultrastructural changes were evaluated by electron microscope. Correlation between LV diastolic function and myocardial ultrastructural changes was examined. It was suggested that preoperative LV diastolic dysfunction occurred earlier than LV systolic dysfunction in patients with AR and MR. LV early diastolic dysfunction was especially significant in patients with AR. LV systolic function was significantly improved postoperatively compared with LV diastolic function in patients with AR and MR. It was suggested that LV interstitial fibrosis caused LV diastolic dysfunction in patients with AR and MR, and insufficiency of myocardial thickening as compensation in patients with MR. It was presumed that LV diastolic dysfunction was irreversible in patients with AR and MR in the distant postoperative period due to persistence of the preoperative myocardial ultrastructural change, e.g., interstitial fibrosis. These LV diastolic indices measured by gated pool scintigraphy were useful in predicting LV ultrastructural changes and postoperative LV dysfunction in patients with LV volume-overloaded valvular heart disease. (author).

  6. Effect of Intensive Blood Pressure Lowering on Left Ventricular Hypertrophy in Patients With Diabetes Mellitus: Action to Control Cardiovascular Risk in Diabetes Blood Pressure Trial

    National Research Council Canada - National Science Library

    Soliman, Elsayed Z; Byington, Robert P; Bigger, J Thomas; Evans, Gregory; Okin, Peter M; Goff, Jr, David C; Chen, Haiying

    2015-01-01

    .... Regression of LVH is achievable by sustained lowering of systolic blood pressure (BP). However, it is unknown whether a strategy aimed at lowering BP beyond that recommended would lower the risk of LVH...

  7. Active Control of Stationary Vortices

    Science.gov (United States)

    Nino, Giovanni; Breidenthal, Robert; Bhide, Aditi; Sridhar, Aditya

    2016-11-01

    A system for active stationary vortex control is presented. The system uses a combination of plasma actuators, pressure sensors and electrical circuits deposited on aerodynamic surfaces using printing electronics methods. Once the pressure sensors sense a change on the intensity or on the position of the stationary vortices, its associated controller activates a set of plasma actuator to return the vortices to their original or intended positions. The forces produced by the actuators act on the secondary flow in the transverse plane, where velocities are much less than in the streamwise direction. As a demonstration case, the active vortex control system is mounted on a flat plate under low speed wind tunnel testing. Here, a set of vortex generators are used to generate the stationary vortices and the plasma actuators are used to move them. Preliminary results from the experiments are presented and compared with theoretical values. Thanks to the USAF AFOSR STTR support under contract # FA9550-15-C-0007.

  8. Ventricular transcriptional data provide mechanistic insights into diesel exhaust induced attenuation of cardiac contractile response and blood pressure

    Science.gov (United States)

    Human exposures to near road ambient particulate matter and its major component, diesel exhaust (DE), have been associated with cardiovascular impairments however the mechanisms and the role of hypertension are not well understood. We have shown that DE exposure reduces blood pre...

  9. Persistent blood stream infection in patients supported with a continuous-flow left ventricular assist device is associated with an increased risk of cerebrovascular accidents.

    Science.gov (United States)

    Trachtenberg, Barry H; Cordero-Reyes, Andrea M; Aldeiri, Molham; Alvarez, Paulino; Bhimaraj, Arvind; Ashrith, Guha; Elias, Barbara; Suarez, Erik E; Bruckner, Brian; Loebe, Matthias; Harris, Richard L; Zhang, J Yi; Torre-Amione, Guillermo; Estep, Jerry D

    2015-02-01

    Common adverse events in patients supported with Continuous-flow left ventricular assist devices (CF-LVAD) include infections and cerebrovascular accidents (CVA). Some studies have suggested a possible association between blood stream infection (BSI) and CVA. Medical records of patients who received Heartmate II (HMII) CF-LVADs in 2008-2012 at a single center were reviewed. CVA was categorized as either hemorrhagic (HCVA) or ischemic (ICVA). BSI was divided into persistent (pBSI) and nonpersistent (non-pBSI). pBSI was defined as BSI with the same organism on repeated blood culture >72 hours from initial blood culture despite antibiotics. Univariate and multivariate analyses were performed to determine predictors. A total of 149 patients had HMII implanted; 76% were male, and the overall mean age was 55.4 ± 13 years. There were a total of 19 (13%) patients who had CVA (7 HCVA and 12 ICVA) at a median of 295 days (range 5-1,096 days) after implantation. There were a total of 28 (19%) patients with pBSI and 17 (11%) patients with non-pBSI. Patients with pBSI had a trend toward greater BMI (31 kg/m(2) vs 27 kg/m(2); P = .09), and longer duration of support (1,019 d vs 371 d; P < .001) compared with those with non-pBSI. Persistent BSI was associated with an increased risk of mortality and with all-cause CVA on multivariate analysis (odds ratio [OR] 5.97; P = .003) as well as persistent Pseudomonas aeruginosa infection (OR 4.54; P = .048). Persistent BSI is not uncommon in patients supported by CF-LVAD and is highly associated with all-cause CVA and increased all-cause mortality. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Vitality of optical vortices (Presentation)

    CSIR Research Space (South Africa)

    Roux, FS

    2014-02-01

    Full Text Available This presentation discusses the vitality of optical vortices to distinguish between vortex dipole creation and annihilation events. Vitality is expressed in terms of the transverse 1st and 2nd order derivatives of the optical field. It can be used...

  11. Unstable vortices do not confine

    NARCIS (Netherlands)

    Achúcarro, A.; Roo, M. de; Huiszoon, L.; Landshoff, P.V.

    1998-01-01

    Recently, a geometric model for the confinement of magnetic charges in the context of type II string compactifications was constructed. This model assumes the existence of stable magnetic vortices with quantized flux in the low energy theory. However, quantization of flux alone does not imply that

  12. Review of vortices in wildland fire

    Science.gov (United States)

    Jason M. Forthofer; Scott L. Goodrick

    2011-01-01

    Vortices are almost always present in the wildland fire environment and can sometimes interact with the fire in unpredictable ways, causing extreme fire behavior and safety concerns. In this paper, the current state of knowledge of the interaction of wildland fire and vortices is examined and reviewed. A basic introduction to vorticity is given, and the two common...

  13. Exercise effects on cardiac size and left ventricular diastolic function: relationships to changes in fitness, fatness, blood pressure and insulin resistance.

    Science.gov (United States)

    Stewart, K J; Ouyang, P; Bacher, A C; Lima, S; Shapiro, E P

    2006-07-01

    To determine exercise training effects on cardiac size and left ventricular (LV) diastolic function and relationships of exercise induced changes in physiological and body composition parameters with cardiac parameters. Prospective, randomised controlled trial. Men and women (63.6 (5.7) years, body mass index 29.5 (4.4) kg/m(2)) with untreated hypertension (systolic blood pressure (BP) 130-159 or diastolic BP 85-99 mm Hg). Cardiac size and LV diastolic function, peak oxygen uptake (Vo(2)), muscle strength, general and abdominal fatness, and insulin resistance. 6 months of exercise training versus usual care. When analysed by group at six months, cardiac size and LV diastolic function did not differ between exercisers (n = 51) and controls (n = 53), whereas exercisers had significantly higher peak Vo(2) (28 v 24 ml/kg/min) and strength (383 v 329 kg), and lower fatness (34% v 37%), diastolic BP (73 v 75 mm Hg) and insulin resistance (quantitative insulin sensitivity check index 0.35 v 0.34) versus controls (all p fitness and reductions in abdominal fatness, insulin resistance and BP showed a modest trend towards physiological hypertrophy characterised by increased cardiac size and improved LV diastolic function. These results suggest that decreased abdominal fatness may have a role in improving cardiovascular health.

  14. Genetic variation in angiotensin II type 2 receptor gene influences extent of left ventricular hypertrophy in hypertrophic cardiomyopathy independent of blood pressure.

    Science.gov (United States)

    Carstens, Nadia; van der Merwe, Lize; Revera, Miriam; Heradien, Marshall; Goosen, Althea; Brink, Paul A; Moolman-Smook, Johanna C

    2011-09-01

    Hypertrophic cardiomyopathy (HCM), an inherited primary cardiac disorder mostly caused by defective sarcomeric proteins, serves as a model to investigate left ventricular hypertrophy (LVH). HCM manifests extreme variability in the degree and distribution of LVH, even in patients with the same causal mutation. Genes coding for renin-angiotensin-aldosterone system components have been studied as hypertrophy modifiers in HCM, with emphasis on the angiotensin (Ang) II type 1 receptor (AT(1)R). However, Ang II binding to Ang II type 2 receptors (AT(2)R) also has hypertrophy-modulating effects. We investigated the effect of the functional +1675 G/A polymorphism (rs1403543) and additional single nucleotide polymorphisms in the 3' untranslated region of the AT(2)R gene (AGTR2) on a heritable composite hypertrophy score in an HCM family cohort in which HCM founder mutations segregate. We find significant association between rs1403543 and hypertrophy, with each A allele decreasing the average wall thickness by ~0.5 mm, independent of the effects of the primary HCM causal mutation, blood pressure and other hypertrophy covariates (p = 0.020). This study therefore confirms a hypertrophy-modulating effect for AT(2)R also in HCM and implies that +1675 G/A could potentially be used in a panel of markers that profile a genetic predisposition to LVH in HCM.

  15. Exercise blood pressure response during assisted circulatory support: comparison of the total artificial [corrected] heart with a left ventricular assist device during rehabilitation.

    Science.gov (United States)

    Kohli, Harajeshwar S; Canada, Justin; Arena, Ross; Tang, Daniel G; Peberdy, Mary Ann; Harton, Suzanne; Flattery, Maureen; Doolin, Kelly; Katlaps, Gundars J; Hess, Michael L; Kasirajan, Vigneshwar; Shah, Keyur B

    2011-11-01

    The total artificial heart (TAH) consists of two implantable pneumatic pumps that replace the heart and operate at a fixed ejection rate and ejection pressure. We evaluated the blood pressure (BP) response to exercise and exercise performance in patients with a TAH compared to those with a with a continuous-flow left ventricular assist device (LVAD). We conducted a single-center, retrospective study of 37 patients who received a TAH and 12 patients implanted with an LVAD. We measured the BP response during exercise, exercise duration and change in tolerated exercise workload over an 8-week period. In patients with a TAH, baseline BP was 120/69 ± 13/13, exercise BP was 118/72 ± 15/10 and post-exercise BP was 120/72 ± 14/12. Mean arterial BP did not change with exercise in patients with a TAH (88 ± 10 vs 88 ± 11; p = 0.8), but increased in those with an LVAD (87 ± 8 vs 95 ± 13; p Heart and Lung Transplantation. All rights reserved.

  16. Pulmonary blood supply by a branch from the distal ascending aorta in pulmonary atresia with ventricular septal defect: differential diagnosis of fifth aortic arch.

    Science.gov (United States)

    Yoo, S J; Moes, C A; Burrows, P E; Molossi, S; Freedom, R M

    1993-10-01

    A patient with pulmonary atresia and a ventricular septal defect is described in whom an arterial branch from the distal ascending aorta supplied segments of both lungs. The branch is considered to represent a persistent fifth aortic arch. The possible morphogenesis and differential diagnosis of a communication between the ascending aorta and the pulmonary artery in pulmonary atresia with ventricular septal defect are discussed.

  17. Chiral vortical effect for bosons

    Science.gov (United States)

    Avkhadiev, Artur; Sadofyev, Andrey V.

    2017-08-01

    The thermal contribution to the chiral vortical effect is believed to be related to the axial anomaly in external gravitational fields. We use the universality of the spin-gravity interaction to extend this idea to a wider set of phenomena. We consider the Kubo formula at weak coupling for the spin current of a vector field and derive a novel anomalous effect caused by the medium rotation: the chiral vortical effect for bosons. The effect consists in a spin current of vector bosons along the angular velocity of the medium. We argue that it has the same anomalous nature as in the fermionic case and show that this effect provides a mechanism for helicity transfer, from flow helicity to magnetic helicity.

  18. Vortical flows in technical applications

    OpenAIRE

    Krause, Egon

    2006-01-01

    Two examples of flows dominated by vortical structures are discussed: In the first interaction and decay of vortex structures in in-cylinder flows of automotive engines are described. Numerical studies revealed clearly identifiable vortex rings, generated during the intake stroke. The influence of compressibility on the vortex formation was studied by using Mach-Zehnder interferometry in a specially designed test stand of a towed one-cylinder engine, and with numerical solutions of the Navier...

  19. Vortices in polariton OPO superfluids

    OpenAIRE

    Marchetti, F. M.; Szymanska, M. H.

    2012-01-01

    his chapter reviews the occurrence of quantised vortices in polariton fluids, primarily when polaritons are driven in the optical parametric oscillator (OPO) regime. We first review the OPO physics, together with both its analytical and numerical modelling, the latter being necessary for the description of finite size systems. Pattern formation is typical in systems driven away from equilibrium. Similarly, we find that uniform OPO solutions can be unstable to the spontaneous formation of quan...

  20. Buoyancy-Induced, Columnar Vortices

    Science.gov (United States)

    Simpson, Mark; Glezer, Ari

    2015-11-01

    Free buoyancy-induced, columnar vortices (dust devils) that are driven by thermal instabilities of ground-heated, stratified air in areas with sufficient insolation convert the potential energy of low-grade heat in the surface air layer into a vortex flow with significant kinetic energy. A variant of the naturally-occurring vortex is deliberately triggered and anchored within an azimuthal array of vertical, stator-like flow vanes that form an open-top enclosure and impart tangential momentum to the radially entrained air. This flow may be exploited for power generation by coupling the vortex to a vertical-axis turbine. The fundamental mechanisms associated with the formation, evolution, and dynamics of an anchored, buoyancy-driven columnar vortex within such a facility are investigated experimentally using a heated ground plane. Specific emphasis is placed on the manipulation of the vortex formation and structure and the dependence of the vorticity production and sustainment mechanisms on the thermal resources and characteristic scales of the anchoring flow vanes using stereo-PIV. It is shown that manipulation of the formation and advection of vorticity concentrations within the enclosure can be exploited for increasing the available kinetic energy. Supported by ARPA-E.

  1. Vortices vacate vales and other singular tales

    Science.gov (United States)

    Turner, Ari Mark

    Quantized vortices in superfluids are a microscopic analogue of the vortices found in a sink as the water rushes down the drain. Unlike ordinary vortices, vortices in superfluid helium or artificial Bose condensates are particle-like because they are very long-lived. My thesis discusses forces experienced by these vortices which have a geometric origin. The first part focuses on vortices in a layer of liquid helium on a curved substrate. Such vortices experience a force that has Gaussian curvature as its source; vortices are attracted to negative and repelled from positive Gaussian curvature. Ideas about contexts where this force might be observed experimentally and the conformal mapping techniques for calculating the strength of the force are presented. The second part focuses on predictions about vortices in a dilute optically trapped Bose condensate of spinor atoms and derives their properties from first principles. Now the atoms' internal spin space provides the nontrivial geometry; spinor states can be classified by introducing a set of points on the sphere called "spin roots". The spin two phase diagram is determined as a function of the interaction parameters. Homotopy theory shows that multiple types of vortices can be created in a condensate of spin two atoms. The interactions between these vortices can be calculated using the spin roots' symmetry group. Metastable vortex states can arise in both contexts. A vortex on a curved surface be trapped near a saddle point. If thermal fluctuations push the vortex away from the saddle, it can move to the edge of the film and disappear, releasing the kinetic energy of the superfluid currents that circle the vortex. Sets of vortices in a spinor condensate can trap each other in a molecule (in the presence of a magnetic field). After a long time, thermal fluctuations can bring the component molecules together, leading to a "chemical reaction" in which new vortices that are not trapped are produced. Then the molecule

  2. Making sound vortices by metasurfaces

    CERN Document Server

    Ye, Liping; Lu, Jiuyang; Tang, Kun; Jia, Han; Ke, Manzhu; Peng, Shasha; Liu, Zhengyou

    2016-01-01

    Based on the Huygens-Fresnel principle, a metasurface structure is designed to generate a sound vortex beam in airborne environment. The metasurface is constructed by a thin planar plate perforated with a circular array of deep subwavelength resonators with desired phase and amplitude responses. The metasurface approach in making sound vortices is validated well by full-wave simulations and experimental measurements. Potential applications of such artificial spiral beams can be anticipated, as exemplified experimentally by the torque effect exerting on an absorbing disk.

  3. Making sound vortices by metasurfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Liping; Qiu, Chunyin, E-mail: cyqiu@whu.edu.cn; Lu, Jiuyang; Tang, Kun; Ke, Manzhu; Peng, Shasha [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Jia, Han [State Key Laboratory of Acoustics and Key Laboratory of Noise and Vibration Research, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Zhengyou [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Institute for Advanced Studies, Wuhan University, Wuhan 430072 (China)

    2016-08-15

    Based on the Huygens-Fresnel principle, a metasurface structure is designed to generate a sound vortex beam in airborne environment. The metasurface is constructed by a thin planar plate perforated with a circular array of deep subwavelength resonators with desired phase and amplitude responses. The metasurface approach in making sound vortices is validated well by full-wave simulations and experimental measurements. Potential applications of such artificial spiral beams can be anticipated, as exemplified experimentally by the torque effect exerting on an absorbing disk.

  4. Hemodynamic effects of ventricular defibrillation

    Science.gov (United States)

    Pansegrau, Donald G.; Abboud, François M.

    1970-01-01

    Hemodynamic responses to ventricular defibrillation were studied in anesthetized dogs. Observations were made on arterial, right atrial and left ventricular end-diastolic pressures, on cardiac output (dye dilution), heart rate, and right atrial electrocardiogram. Ventricular fibrillation was induced electrically with a bipolar electrode catheter placed in the right ventricle. Fibrillation was maintained for 15 or 30 sec and terminated with a 400 w sec capacitor discharge across the thoracic cage. Responses lasted 1-10 min after conversion and included a cholinergic and an adrenergic component. The cholinergic component was characterized by sinus bradycardia, periods of sinus arrest, atrioventricular block, and ventricular premature beats. The adrenergic component included increases in arterial pressure, in cardiac output, and in left ventricular stroke work at a time when left ventricular end-diastolic pressure was normal; there was no change in total peripheral resistance. The pH of arterial blood decreased slightly and pCO2 increased but pO2 and the concentration of lactate were unchanged. Bilateral vagotomy and intravenous administration of atropine blocked the cholinergic component, unmasked a sinus tachycardia, and accentuated the adrenergic component of the response. The latter was blocked by intravenous administration of propranolol and phenoxybenzamine. These responses were related primarily to conversion of ventricular fibrillation rather than to the electrical discharge of countershock because countershock without ventricular fibrillation caused more transient and smaller responses than those observed with defibrillation: furthermore, the hemodynamic effects of defibrillation were augmented by prolongation of the duration of fibrillation. The results suggest that the cholinergic component of the response may be detrimental in that it favors spontaneous recurrence of fibrillation; on the other hand, the adrenergic component may be essential for conversion

  5. Myocardial blood flow and left ventricular functional reserve in hypertrophic cardiomyopathy: a {sup 13}NH{sub 3} gated PET study

    Energy Technology Data Exchange (ETDEWEB)

    Sciagra, Roberto; Calabretta, Raffaella; Passeri, Alessandro; Castello, Angelo; Pupi, Alberto [University of Florence, Nuclear Medicine Unit, Department of Experimental and Clinical Biomedical Sciences ' ' Mario Serio' ' , Florence (Italy); Cipollini, Fabrizio [University of Florence, Department of Statistics, Florence (Italy); Cecchi, Franco; Olivotto, Iacopo [Careggi University Hospital, Referral Centre for Myocardial Diseases, Florence (Italy)

    2017-05-15

    Ischemia in hypertrophic cardiomyopathy (HCM) is caused by coronary microvascular dysfunction (CMD), which is detected by measuring myocardial blood flow (MBF) with PET. Whether CMD may be associated with ischemic left ventricular (LV) dysfunction is unclear. We therefore assessed LV ejection fraction (EF) reserve in HCM patients undergoing dipyridamole (Dip) PET. Resting and stress {sup 13}NH{sub 3} dynamic as well as gated PET were performed in 34 HCM patients. Segmental MBF and transmural perfusion gradient (TPG = subendocardial / subepicardial MBF) were assessed. LVEF reserve was considered abnormal if Dip LVEF decreased more than 5 units as compared to rest. Eighteen patients had preserved (group A) and 16 abnormal LVEF reserve (group B; range -7 to -32). Group B patients had greater wall thickness than group A, but resting volumes, LVEF, resting and Dip MBF, and myocardial flow reserve were similar. Group B had slightly higher summed stress score and summed difference score in visual analysis than group A, and a significantly higher summed stress wall motion score. In group B, resting TPG was slightly lower (1.31 ± 0.29 vs. 1.37 ± 0.34, p <0.05), and further decreased after Dip, whilst in group A it increased (B = 1.20 ± 0.39, p < 0.0001 vs. rest and vs. A = 1.40 ± 0.43). The number of segments per patient with TPG <1 was higher than in group A (p < 0.001) and was a significant predictor of impaired LVEF reserve (OR 1.86, p < 0.02), together with wall thickness (OR 1.3, p < 0.02). Abnormal LVEF response is common in HCM patients following Dip, and is related to abnormal TPG, suggesting that subendocardial ischemia might occur under Dip and cause transient LV dysfunction. Although in vivo this effect may be hindered by the adrenergic drive associated with effort, these findings may have relevance in understanding exercise limitation and heart failure symptoms in HCM. (orig.)

  6. Discussion on the complete-form vorticity equation and slantwise vorticity development

    Science.gov (United States)

    Wang, Xiuming; Zhou, Xiaogang; Tao, Zuyu; Liu, Hua

    2016-02-01

    The complete form of the vertical vorticity tendency equation (the complete-form vorticity equation) is derived from the Ertel potential vorticity equation to contain thermodynamic factors. In this study, a new complete-form vorticity equation, which has the same form as the original complete-form vorticity equation, is deduced from the absolute vorticity vector equation combined with the continuity equation and the expression of three-dimensional (3D) entropy gradient. By comparing the complete-form vorticity equation with the classical vertical vorticity equation, it is found that regardless of whether or not the isentropic surface is tilting, the two vorticity equations are in essence the same. The "baroclinic term" of the complete-form vorticity equation is exactly equal to the solenoidal term of the classical one, and there is a significant amount of cancellation between the two baroclinic items (the "slantwise term" and the horizontal vorticity change term) in the complete-form vorticity equation. In operational weather analysis, the tilt of the isentropic surface can be diagnosed according to the density of the isotherm on the upper-level isobaric map. For synoptic-scale motion, the vertical vorticity produced by the tilt of the isentropic surface is due to the contribution of atmospheric baroclinicity, which is measured by the solenoid. The 3D solenoid is parallel to the isentropic surface, so the more tilted the isentropic surface, the bigger the projection of the 3D solenoid in the vertical direction. The baroclinic contribution can be interpreted based on the PV thinking theory, but the relationship between the vorticity field and the potential vorticity field is not immediate.

  7. On generating counter-rotating streamwise vortices

    KAUST Repository

    Winoto, S H

    2015-09-23

    Counter-rotating streamwise vortices are known to enhance the heat transfer rate from a surface and also to improve the aerodynamic performance of an aerofoil. In this paper, some methods to generate such counter-rotating vortices using different methods or physical conditions will be briefly considered and discussed.

  8. Blood

    Science.gov (United States)

    ... organs and show how well treatments are working. Problems with your blood may include bleeding disorders, excessive clotting and platelet disorders. If you lose too much blood, you may need a transfusion. NIH: National Heart, Lung, and Blood Institute

  9. Magnetic gates and guides for superconducting vortices

    Science.gov (United States)

    Vlasko-Vlasov, V. K.; Colauto, F.; Buzdin, A. I.; Rosenmann, D.; Benseman, T.; Kwok, W.-K.

    2017-04-01

    We image the motion of superconducting vortices in niobium film covered with a regular array of thin permalloy strips. By altering the magnetization orientation in the strips using a small in-plane magnetic field, we can tune the strength of interactions between vortices and the strip edges, enabling acceleration or retardation of the superconducting vortices in the sample and consequently introducing strong tunable anisotropy into the vortex dynamics. We discuss our observations in terms of the attraction/repulsion between point magnetic charges carried by vortices and lines of magnetic charges at the strip edges and derive analytical formulas for the vortex-magnetic strips coupling. Our approach demonstrates the analogy between the vortex motion regulated by the magnetic strip array and electric carrier flow in gated semiconducting devices. Scaling down the geometrical features of the proposed design may enable controlled manipulation of single vortices, paving the way for Abrikosov vortex microcircuits and memories.

  10. Theory of concentrated vortices an introduction

    CERN Document Server

    Alekseenko, S V; Okulov, V L

    2007-01-01

    Vortex motion is one of the basic states of a flowing continuum. Intere- ingly, in many cases vorticity is space-localized, generating concentrated vortices. Vortex filaments having extremely diverse dynamics are the most characteristic examples of such vortices. Notable examples, in particular, include such phenomena as self-inducted motion, various instabilities, wave generation, and vortex breakdown. These effects are typically ma- fested as a spiral (or helical) configuration of a vortex axis. Many publications in the field of hydrodynamics are focused on vortex motion and vortex effects. Only a few books are devoted entirely to v- tices, and even fewer to concentrated vortices. This work aims to highlight the key problems of vortex formation and behavior. The experimental - servations of the authors, the impressive visualizations of concentrated vortices (including helical and spiral) and pictures of vortex breakdown primarily motivated the authors to begin this work. Later, the approach based on the hel...

  11. Magnetoplasmonic control of plasmonic vortices

    Science.gov (United States)

    Maccaferri, Nicolò; Gorodetski, Yuri; Toma, Andrea; Zilio, Pierfrancesco; De Angelis, Francesco; Garoli, Denis

    2017-11-01

    We theoretically investigate the generation of far-field propagating optical beams with a desired orbital angular momentum by using an archetypical magnetoplasmonic tip surrounded by a gold spiral slit. The use of a magnetic material can lead to important implications once magneto-optical activity is activated through the application of an external magnetic field. The physical model and the numerical study presented here introduce the concept of magnetically tunable plasmonic vortex lens, namely a magnetoplasmonic vortex lens, which ensures a tunable selectivity in the polarization state of the generated nanostructured beam. The presented system provides a promising platform for a localized excitation of plasmonic vortices followed by their beaming in the far-field with an active modulation of both light's transmission and helicity.

  12. Ventricular hypertrophy in cardiomyopathy.

    Science.gov (United States)

    Oakley, C

    1971-01-01

    Semantic difficulties arise when hypertrophic obstructive cardiomyopathy is seen without obstruction and with congestive failure, and also when congestive cardiomyopathy is seen with gross hypertrophy but without heart failure. Retention of a small left ventricular cavity and a normal ejection fraction characterizes hypertrophic cardiomyopathy at all stages of the disorder. Congestive cardiomyopathy is recognized by the presence of a dilated left ventricular cavity and reduced ejection fraction regardless of the amount of hypertrophy and the presence or not of heart failure. Longevity in congestive cardiomyopathy seems to be promoted when hypertrophy is great relative to the amount of pump failure as measured by increase in cavity size. Conversely, death in hypertrophic cardiomyopathy is most likely when hypertrophy is greatest at a time when outflow tract obstruction has been replaced by inflow restriction caused by diminishing ventricular distensibility. Hypertrophy is thus beneficial and compensatory in congestive cardiomyopathy, whereas it may be the primary disorder and eventual cause of death in hypertrophic cardiomyopathy. Reasons are given for believing that hypertension may have been the original cause of left ventricular dilatation in some case of congestive cardiomyopathy in which loss of stroke output thenceforward is followed by normotension. Development of severe hypertension in these patients after recovery from a prolonged period of left ventricular failure with normotension lends weight to this hypothesis. No fault has been found in the large or small coronary arteries in either hypertrophic cardiomyopathy or congestive cardiomyopathy when they have been examined in life by selective coronary angiography, or by histological methods in biopsy or post-mortem material. Coronary blood supply may be a limiting factor in the compensatory hypertrophy of congestive cardiomyopathy, and the ability to hypertrophy may explain the better prognosis of some

  13. A vorticity budget for the Gulf Stream

    Science.gov (United States)

    Le Bras, Isabela; Toole, John

    2017-04-01

    We develop a depth-averaged vorticity budget framework to diagnose the dynamical balance of the Gulf Stream, and apply this framework to observations and the ECCO state estimate (Wunsch and Heimbach 2013) above the thermocline in the subtropical North Atlantic. Using the hydrographic and ADCP data along the WOCE/CLIVAR section A22 and a variety of wind stress data products, we find that the advective vorticity flux out of the western region is on the same order as the wind stress forcing over the eastern portion of the gyre. This is consistent with a large-scale balance between a negative source of vorticity from wind stress forcing and a positive source of vorticity in the western region. Additionally, the form of the vorticity flux indicates that the Gulf Stream has a significant inertial component. In the ECCO state estimate, we diagnose a seasonal cycle in advective vorticity flux across a meridional section associated with seasonal fluctuations in Gulf Stream transport. This vorticity flux is forced by wind stress over the eastern subtropical North Atlantic and balanced by lateral friction with the western boundary. The lateral friction in ECCO is a necessary parameterization of smaller scale processes that occur in the real ocean, and quantifying these remains an open and interesting question. This simplified framework provides a means to interpret large scale ocean dynamics. In our application, it points to wind stress forcing over the subtropical North Altantic as an important regulator of the Gulf Stream and hence the climate system.

  14. Assessment of intracardiac flow and vorticity in the right heart of patients after repair of tetralogy of Fallot by flow-sensitive 4D MRI

    Energy Technology Data Exchange (ETDEWEB)

    Hirtler, Daniel [University Hospital Freiburg, Department of Congenital Heart Defects and Pediatric Cardiology (Heart Center, University of Freiburg), Freiburg (Germany); Garcia, Julio; Barker, Alex J. [Northwestern University Feinberg School of Medicine, Department of Radiology, Chicago, IL (United States); Geiger, Julia [University Childrens' Hospital Zurich, Department of Radiology, Zurich (Switzerland)

    2016-10-15

    To comprehensively and quantitatively analyse flow and vorticity in the right heart of patients after repair of tetralogy of Fallot (rTOF) compared with healthy volunteers. Time-resolved flow-sensitive 4D MRI was acquired in 24 rTOF patients and 12 volunteers. Qualitative flow evaluation was based on consensus reading of two observers. Quantitative analysis included segmentation of the right atrium (RA) and ventricle (RV) in a four-chamber view to extract volumes and regional haemodynamic information for computation of regional mean and peak vorticity. Right heart intra-atrial, intraventricular and outflow tract flow patterns differed considerably between rTOF patients and volunteers. Peak RA and mean RV vorticity was significantly higher in patients (p = 0.02/0.05). Significant negative correlations were found between patients' maximum and mean RV and RA vorticity and ventricular volumes (p < 0.05). The main pulmonary artery (MPA) regurgitant flow was associated with higher RA and RV vorticity, which was significant for RA maximum and RV mean vorticity (p = 0.01/0.03). The calculation of vorticity based on 4D flow data is an alternative approach to assess intracardiac flow changes in rTOF patients compared with qualitative flow visualization. Alterations in intracardiac vorticity could be relevant with regard to the development of RV dilation and impaired function. (orig.)

  15. Correlations between Abelian monopoles and center vortices

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini Nejad, Seyed Mohsen, E-mail: smhosseininejad@ut.ac.ir; Deldar, Sedigheh, E-mail: sdeldar@ut.ac.ir

    2017-04-15

    We study the correlations between center vortices and Abelian monopoles for SU(3) gauge group. Combining fractional fluxes of monopoles, center vortex fluxes are constructed in the thick center vortex model. Calculating the potentials induced by fractional fluxes constructing the center vortex flux in a thick center vortex-like model and comparing with the potential induced by center vortices, we observe an attraction between fractional fluxes of monopoles constructing the center vortex flux. We conclude that the center vortex flux is stable, as expected. In addition, we show that adding a contribution of the monopole-antimonopole pairs in the potentials induced by center vortices ruins the Casimir scaling at intermediate regime.

  16. Vortices and turbulence in trapped atomic condensates

    Science.gov (United States)

    White, Angela C.; Anderson, Brian P.; Bagnato, Vanderlei S.

    2014-01-01

    After more than a decade of experiments generating and studying the physics of quantized vortices in atomic gas Bose–Einstein condensates, research is beginning to focus on the roles of vortices in quantum turbulence, as well as other measures of quantum turbulence in atomic condensates. Such research directions have the potential to uncover new insights into quantum turbulence, vortices, and superfluidity and also explore the similarities and differences between quantum and classical turbulence in entirely new settings. Here we present a critical assessment of theoretical and experimental studies in this emerging field of quantum turbulence in atomic condensates. PMID:24704880

  17. Atmospheric Vortices near Guadalupe Island

    Science.gov (United States)

    2000-01-01

    These MISR images from June 11, 2000 (Terra orbit 2569) demonstrate a turbulent atmospheric flow pattern known as the von Karman vortex street. This phenomenon is named after aerodynamicist Theodore von Karman, who theoretically derived the conditions under which it occurs. The alternating double row of vortices can form in the wake of an obstacle, in this instance the eastern Pacific island of Guadalupe. The rugged terrain of this volcanic Mexican island reaches a maximum elevation of 1.3 kilometers. The island is about 35 kilometers long and is located 260 kilometers west of Baja California.The vortex pattern is made visible by the marine stratocumulus clouds around Guadalupe Island. The upper image is a color view obtained by MISR's vertical-viewing (nadir) camera. North is toward the left. The orientation of the vortex street indicates that the wind direction is from lower left to upper right (northwest to southeast). The areas within the vortex centers tend to be clear because the rotating motions induce a vertical wind component that can break up the cloud deck.The lower view is a stereo picture generated from data acquired by MISR's fore- and aft-viewing 70-degree cameras. A 3-D effect is obtained by viewing the image with red/blue glasses and placing the red filter over your left eye. Note how the downwelling atmospheric motion (change in elevation from high to low) is accompanied by a clearing in the center of the first vortex. As the vortices propagate downstream, their rotational velocities weaken. As a consequence, the induced vertical motion and cloud-clearing effect weakens as well.Theodore von Karman was a Professor of Aeronautics at Caltech and Director of Caltech's Guggenheim Aeronautical Laboratory from 1930-1949. He was one of the principal founders of the Jet Propulsion Laboratory.MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by

  18. Right Ventricular Perfusion: Physiology and Clinical Implications.

    Science.gov (United States)

    Crystal, George J; Pagel, Paul S

    2018-01-01

    Regulation of blood flow to the right ventricle differs significantly from that to the left ventricle. The right ventricle develops a lower systolic pressure than the left ventricle, resulting in reduced extravascular compressive forces and myocardial oxygen demand. Right ventricular perfusion has eight major characteristics that distinguish it from left ventricular perfusion: (1) appreciable perfusion throughout the entire cardiac cycle; (2) reduced myocardial oxygen uptake, blood flow, and oxygen extraction; (3) an oxygen extraction reserve that can be recruited to at least partially offset a reduction in coronary blood flow; (4) less effective pressure-flow autoregulation; (5) the ability to downregulate its metabolic demand during coronary hypoperfusion and thereby maintain contractile function and energy stores; (6) a transmurally uniform reduction in myocardial perfusion in the presence of a hemodynamically significant epicardial coronary stenosis; (7) extensive collateral connections from the left coronary circulation; and (8) possible retrograde perfusion from the right ventricular cavity through the Thebesian veins. These differences promote the maintenance of right ventricular oxygen supply-demand balance and provide relative resistance to ischemia-induced contractile dysfunction and infarction, but they may be compromised during acute or chronic increases in right ventricle afterload resulting from pulmonary arterial hypertension. Contractile function of the thin-walled right ventricle is exquisitely sensitive to afterload. Acute increases in pulmonary arterial pressure reduce right ventricular stroke volume and, if sufficiently large and prolonged, result in right ventricular failure. Right ventricular ischemia plays a prominent role in these effects. The risk of right ventricular ischemia is also heightened during chronic elevations in right ventricular afterload because microvascular growth fails to match myocyte hypertrophy and because microvascular

  19. Blood

    Science.gov (United States)

    ... anemia. Iron deficiency anemia is the most common type of anemia and can affect people who have a diet ... 2015 More on this topic for: Teens Blood Types Donating Blood Blood Transfusions Anemia Sickle Cell Disease Hemophilia When Cancer Keeps You ...

  20. Chaotic vortical flows and their manifestations

    Directory of Open Access Journals (Sweden)

    Baznat M.

    2016-01-01

    Full Text Available We study vorticity and hydrodynamic helicity in semi-peripheral heavy-ion collisions using the kinetic model of Quark-Gluon Strings. The angular momentum, which is a source of P-odd observables, is preserved with a good accuracy. We observe formation of the specific toroidal structures of the vorticity field. Their existence, accompanied by the strange chemical potential, is mirrored in the polarization of hyperons of the percent order.

  1. Vortices and vortex lattices in quantum ferrofluids.

    Science.gov (United States)

    Martin, A M; Marchant, N G; O'Dell, D H J; Parker, N G

    2017-03-15

    The experimental realization of quantum-degenerate Bose gases made of atoms with sizeable magnetic dipole moments has created a new type of fluid, known as a quantum ferrofluid, which combines the extraordinary properties of superfluidity and ferrofluidity. A hallmark of superfluids is that they are constrained to rotate through vortices with quantized circulation. In quantum ferrofluids the long-range dipolar interactions add new ingredients by inducing magnetostriction and instabilities, and also affect the structural properties of vortices and vortex lattices. Here we give a review of the theory of vortices in dipolar Bose-Einstein condensates, exploring the interplay of magnetism with vorticity and contrasting this with the established behaviour in non-dipolar condensates. We cover single vortex solutions, including structure, energy and stability, vortex pairs, including interactions and dynamics, and also vortex lattices. Our discussion is founded on the mean-field theory provided by the dipolar Gross-Pitaevskii equation, ranging from analytic treatments based on the Thomas-Fermi (hydrodynamic) and variational approaches to full numerical simulations. Routes for generating vortices in dipolar condensates are discussed, with particular attention paid to rotating condensates, where surface instabilities drive the nucleation of vortices, and lead to the emergence of rich and varied vortex lattice structures. We also present an outlook, including potential extensions to degenerate Fermi gases, quantum Hall physics, toroidal systems and the Berezinskii-Kosterlitz-Thouless transition.

  2. Generation and propagation of optical vortices

    Science.gov (United States)

    Rozas, David

    Optical vortices are singularities in phase fronts of laser beams. They are characterized by a dark core whose size (relative to the size of the background beam) may dramatically affect their behavior upon propagation. Previously, only large-core vortices have been extensively studied. The object of the research presented in this dissertation was to explore ways of generating small-core optical vortices (also called optical vortex filaments ), and to examine their propagation using analytical, numerical and experimental methods. Computer-generated holography enabled us to create arbitrary distributions of optical vortex filaments for experimental exploration. Hydrodynamic analogies were used to develop an heuristic model which described the dependence of vortex motion on other vortices and the background beam, both qualitatively and quantitatively. We predicted that pair of optical vortex filaments will rotate with angular rates inversely proportional to their separation distance (just like vortices in a fluid). We also reported the first experimental observation of this novel fluid-like effect. It was found, however, that upon propagation in linear media, the fluid-like rotation was not sustained owing to the overlap of diffracting vortex cores. Further numerical studies and experiments showed that rotation angle may be enhanced in nonlinear self-defocusing media. The results presented in this thesis offer us a better understanding of dynamics of propagating vortices which may result in applications in optical switching, optical data storage, manipulation of micro-particles and optical limiting for eye protection.

  3. Simultaneous Velocity and Vorticity Measurement in Turbulence

    Science.gov (United States)

    Wu, Huixuan; Xu, Haitao; Bodenschatz, Eberhard

    2013-11-01

    A new paradigm of simultaneous velocity and vorticity measurement is developed to study turbulence. Instead of deducing vorticity from velocities measured at neighboring points, this innovative approach detects the translations and rotations of micro-sized particles directly. These hydrogel particles are spherical, transparent, and encapsulate micro-mirrors. This method outstands conventional ones, e.g., hotwire arrays or PIV because its spatial resolution is much higher. It does not require a non-zero mean flow, and it can provide all three vorticity components, which is not available from planar PIV data. Its principle is to illuminate the mirror and utilize the variation of the reflection directions to deduce the local flow vorticity. Meanwhile, the particle position is recorded as in normal particle tracking. Therefore, the velocity and vorticity of a particle can be obtained simultaneously in Lagrangian framework. The authors have made benchmark experiments to evaluate this novel method in Taylor Couette flows. The results show that the instantaneous vorticity measurement is as accurate as 3%. We are now setting up a von Karman disk pair device to study the turbulent flow. This novel technique will provide unprecedented information of high Reynolds number turbulence. The first author thanks the Alexander von Humboldt Foundation.

  4. Arrhythmogenic right ventricular dysplasia

    OpenAIRE

    Bockeria O.L.; Lе T.G.

    2015-01-01

    Arrhythmogenic right ventricular dysplasia is a hereditary cardiomyopathy characterized by structural and functional disorders in the right ventricle, which results in ventricular arrhythmias. Arrhythmogenic right ventricular dysplasia is one of the important causes of sudden cardiac death in young people and athletes. Structural disorders in arrhythmogenic right ventricular dysplasia are associated with fibrosis and fatty infiltration of the right ventricular myocardium. These changes lead t...

  5. Non-β-blocking R-carvedilol enantiomer suppresses Ca2+ waves and stress-induced ventricular tachyarrhythmia without lowering heart rate or blood pressure

    OpenAIRE

    Zhang, Jingqun; Zhou, Qiang; Smith, Chris D.; Chen, Haiyan; Tan, Zhen; Chen, Biyi; Nani, Alma; Wu, Guogen; Song, Long-Sheng; Fill, Michael; Back, Thomas G.; Wayne Chen, S.R.

    2015-01-01

    Carvedilol is the current β-blocker of choice for suppressing ventricular tachyarrhythmia (VT). However, carvedilol’s benefits are dose-limited, attributable to its potent β-blocking activity that can lead to bradycardia and hypotension. The clinically used carvedilol is a racemic mixture of β-blocking S-carvedilol and non-β-blocking R-carvedilol. We recently reported that novel non-β-blocking carvedilol analogues are effective in suppressing arrhythmogenic Ca2+ waves and stress-induced VT wi...

  6. Ventricular septal defect.

    Science.gov (United States)

    Giboney, G S

    1983-05-01

    This article has discussed the ventricular septal defect, its occurrence, physiology, and therapy, and nursing concerns. The VSD, a communication allowing left-to-right shunting of blood at the ventricular level, is the most common congenital heart defect. Surgical correction is often required for large defects before the age of 12 months, and primary correction is now considered standard procedure. Small defects usually close spontaneously, and moderate defects are closely monitored for signs indicating the need for surgical intervention. Nursing care begins with child and family assessment and evaluation of the strengths and weaknesses of the family system. The child's developmental level is a major consideration in formulating interventions for his benefit. Play therapy is a useful vehicle in relating to the child in a nonthreatening manner preoperatively and in allowing the child to work through his hospitalization postoperatively. Maintaining the physical integrity of a child just out of the operating room is a challenge. Continuing support of the family system is a significant aspect of nursing's responsibility toward child and family. Discharge planning and intervention strive to prepare the family for the transition from hospital to home both physically and emotionally.

  7. BLOOD

    African Journals Online (AJOL)

    benefit (altruism). '35 An individual who gives blood in replacement for that which has been given to his relation is referred to as family replacement donor. '2 But when a person donates blood for the purpose of transfusing a. defined patient, such a person is referred to as. AHMED S. G. AND HASSAN A. W. a directed donor.

  8. Initial Circulation and Peak Vorticity Behavior of Vortices Shed from Airfoil Vortex Generators

    Science.gov (United States)

    Wendt, Bruce J.; Biesiadny, Tom (Technical Monitor)

    2001-01-01

    An extensive parametric study of vortices shed from airfoil vortex generators has been conducted to determine the dependence of initial vortex circulation and peak vorticity on elements of the airfoil geometry and impinging flow conditions. These elements include the airfoil angle of attack, chord length, span, aspect ratio, local boundary layer thickness, and free stream Mach number. In addition, the influence of airfoil-to-airfoil spacing on the circulation and peak vorticity has been examined for pairs of co-rotating and counter-rotating vortices. The vortex generators were symmetric airfoils having a NACA-0012 cross-sectional profile. These airfoils were mounted either in isolation, or in pairs, on the surface of a straight pipe. The turbulent boundary layer thickness to pipe radius ratio was about 17 percent. The circulation and peak vorticity data were derived from cross-plane velocity measurements acquired with a seven-hole probe at one chord-length downstream of the airfoil trailing edge location. The circulation is observed to be proportional to the free-stream Mach number, the angle-of-attack, and the span-to-boundary layer thickness ratio. With these parameters held constant, the circulation is observed to fall off in monotonic fashion with increasing airfoil aspect ratio. The peak vorticity is also observed to be proportional to the free-stream Mach number, the airfoil angle-of-attack, and the span-to-boundary layer thickness ratio. Unlike circulation, however, the peak vorticity is observed to increase with increasing aspect ratio, reaching a peak value at an aspect ratio of about 2.0 before falling off again at higher values of aspect ratio. Co-rotating vortices shed from closely spaced pairs of airfoils have values of circulation and peak vorticity under those values found for vortices shed from isolated airfoils of the same geometry. Conversely, counter-rotating vortices show enhanced values of circulation and peak vorticity when compared to values

  9. Stability of helical tip vortices in a rotor far wake

    DEFF Research Database (Denmark)

    Okulov, Valery; Sørensen, Jens Nørkær

    2007-01-01

    , corresponding to Rankine, Gaussian and Scully vortices, at radial extents ranging from the core radius of a tip vortex to several rotor radii. The analysis shows that the stability of tip vortices largely depends on the radial extent of the hub vorticity as well as on the type of vorticity distribution. As part......As a means of analysing the stability of the wake behind a multi-bladed rotor the stability of a multiplicity of helical vortices embedded in an assigned flow field is addressed. In the model the tip vortices in the far wake are approximated by infinitely long helical vortices with constant pitch...... and radius. The work is a further development of a model developed in Okulov (J. Fluid Mech., vol. 521, p. 319) in which the linear stability of N equally azimuthally spaced helical vortices was considered. In the present work the analysis is extended to include an assigned vorticity field due to root...

  10. Central and peripheral blood flow during exercise with a continuous-flow left ventricular assist device: constant versus increasing pump speed: a pilot study

    DEFF Research Database (Denmark)

    Brassard, Patrice; Jensen, Annette S; Nordsborg, Nikolai

    2011-01-01

    with work rate would increase organ blood flow. Methods and Results- Invasively determined CO and leg blood flow and Doppler-determined cerebral perfusion were measured during 2 incremental cycle exercise tests on the same day in 8 patients provided with a HeartMate II LVAD. In random order, patients...

  11. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  12. Dynamics of quantised vortices in superfluids

    CERN Document Server

    Sonin, Edouard B

    2016-01-01

    A comprehensive overview of the basic principles of vortex dynamics in superfluids, this book addresses the problems of vortex dynamics in all three superfluids available in laboratories (4He, 3He, and BEC of cold atoms) alongside discussions of the elasticity of vortices, forces on vortices, and vortex mass. Beginning with a summary of classical hydrodynamics, the book guides the reader through examinations of vortex dynamics from large scales to the microscopic scale. Topics such as vortex arrays in rotating superfluids, bound states in vortex cores and interaction of vortices with quasiparticles are discussed. The final chapter of the book considers implications of vortex dynamics to superfluid turbulence using simple scaling and symmetry arguments. Written from a unified point of view that avoids complicated mathematical approaches, this text is ideal for students and researchers working with vortex dynamics in superfluids, superconductors, magnetically ordered materials, neutron stars and cosmological mo...

  13. Fractional Vortices in Multi-Gap Superconductors

    Science.gov (United States)

    Loh, Yen Lee; Kim, Monica; Kim, Ju H.

    2014-03-01

    Novel topological defects, known as fractional vortices, can occur in thin films of multi-gap superconductors. We study two-gap and three-gap superconducting films within a classical Ginzburg-Landau description, using numerical simulations and analytic approximations. In two-gap superconducting films, we find that the interband Josephson coupling J12 leads to an effective attraction between half-vortices, whereas the permeability parameter μ leads to an effective repulsion between half-vortices. We locate the phase boundary in (J12 , μ) space that marks the onset of spontaneous vortex fractionalization. We describe how the size of a fractional vortex increases as one goes deeper into the fractionalized phase. Our results suggest that coating a multi-gap superconducting film with a paramagnetic overlayer will enhance the tendency towards vortex fractionalization.

  14. Vorticity field measurement using digital inline holography

    Science.gov (United States)

    Mallery, Kevin; Hong, Jiarong

    2017-11-01

    We demonstrate the direct measurement of a 3D vorticity field using digital inline holographic microscopy. Microfiber tracer particles are illuminated with a 532 nm continuous diode laser and imaged using a single CCD camera. The recorded holographic images are processed using a GPU-accelerated inverse problem approach to reconstruct the 3D structure of each microfiber in the imaged volume. The translation and rotation of each microfiber are measured using a time-resolved image sequence - yielding velocity and vorticity point measurements. The accuracy and limitations of this method are investigated using synthetic holograms. Measurements of solid body rotational flow are used to validate the accuracy of the technique under known flow conditions. The technique is further applied to a practical turbulent flow case for investigating its 3D velocity field and vorticity distribution.

  15. Stability of periodic arrays of vortices

    CERN Document Server

    Dauxois, T; Tuckerman, L S; Dauxois, Thierry; Fauve, Stephan; Tuckerman, Laurette

    1995-01-01

    The stability of periodic arrays of Mallier-Maslowe or Kelvin-Stuart vortices is discussed. We derive with the energy-Casimir stability method the nonlinear stability of this solution in the inviscid case as a function of the solution parameters and of the domain size. We exhibit the maximum size of the domain for which the vortex street is stable. By adapting a numerical time-stepping code, we calculate the linear stability of the Mallier-Maslowe solution in the presence of viscosity and compensating forcing. Finally, the results are discussed and compared to a recent experiment in fluids performed by Tabeling et al.~[Europhysics Letters {\\bf 3}, 459 (1987)]. Electromagnetically driven counter-rotating vortices are unstable above a critical electric current, and give way to co-rotating vortices. The importance of the friction at the bottom of the experimental apparatus is also discussed.

  16. Three-dimensional diastolic blood flow in the left ventricle.

    Science.gov (United States)

    Khalafvand, Seyed Saeid; Ng, Eddie Yin-Kwee; Zhong, Liang; Hung, Tin-Kan

    2017-01-04

    Three-dimensional blood flow in a human left ventricle is studied via a computational analysis with magnetic resonance imaging of the cardiac motion. Formation, growth and decay of vortices during the myocardial dilation are analyzed with flow patterns on various diametric planes. They are dominated by momentum transfer during flow acceleration and deceleration through the mitral orifice. The posterior and anterior vortices form an asymmetric annular vortex at the mitral orifice, providing a smooth transition for the rapid inflow to the ventricle. The development of core vortex accommodates momentum for deceleration and for acceleration at end diastolic atrial contraction. The rate of energy dissipation and that of work done by viscous stresses are small; they are approximately balanced with each other. The kinetic energy flux and the rate of work done by pressure delivered to blood from ventricular dilation is well balanced by the total energy influx at the mitral orifice and the rate change of kinetic energy in the ventricle. Published by Elsevier Ltd.

  17. Slow light vortices in periodic waveguides

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Ha, Sangwoo; Desyatnikov, Anton S.

    2009-01-01

    We reveal that the reduction of the group velocity of light in periodic waveguides is generically associated with the presence of vortex energy flows. We show that the energy flows are gradually frozen for slow-light at the Brillouin zone edge, whereas vortices persist for slow-light states having...... non-vanishing phase velocity inside the Brillouin zone. We also demonstrate that presence of vortices can be linked to the absence of slow-light at the zone edge, and present calculations illustrating these general results....

  18. Water waves interacting with a current of constant vorticity: estimating the vorticity of the wave field

    Science.gov (United States)

    Simon, Bruno; Seez, William; Abid, Malek; Kharif, Christian; Touboul, Julien

    2017-04-01

    During the last ten years, the topic of water waves interacting with sheared current has drawn a lot of attention, since the interaction of water waves with vorticity was recently found to be significant when modeling the propagation of water waves. In this framework, the configuration involving constantly sheared current (indeed a constant vorticity) is of special interst, since the equations remain tractable. In this framework, it is demonstrated that the flow related to water waves can be described by means of potential theory, since the source term in the vorticity equation is proportionnal to the curvature of the current profile (Nwogu, 2009). In the mean time, the community often wonders if this argument is valid, since the existence of a perfectly linearly sheared current is purely theoretical, and the presence of the vorticity within the wave field can be external (through wave generation mechanisms, for instance). Thus, this work is dedicated to investigate the magnitude of the vorticity related to the wave field, in conditions similar to this analytical case of constant vorticity. This approach is based on the comparison of experimental data, and three models. The first model is linear, supposing a constantly seared current and water waves described by potential theory. The second is fully nonlinear, but still supposing that water waves are potential, and finally, the third model is fully nonlinear, but solves the Euler equations, allowing the existence of vorticity related to the waves. The confrontation of these three approaches with the experimental data will allow to quantify the wave-related vorticity within the total flow, and analyze its importance as a function of nonlinearity and vorticity magnitude. ACKNOWLEDGEMENTS The DGA (Direction Générale de l'Armement, France) is acknowledged for its financial support through the ANR grant N°ANR-13-ASTR-0007.

  19. Mitigation of Shear-Induced Blood Damage of Mechanical Bileaflet Heart Valves using Embedded Vortex Generators

    Science.gov (United States)

    Hidalgo, Pablo; Arjunon, Sivakkumar; Saikrishnan, Neelakantan; Yoganathan, Ajit; Glezer, Ari

    2012-11-01

    The strong transitory shear stress generated during the time-periodic closing of the mechanical prosthetic bileaflet aortic heart valve, is considered to be one of the main factors responsible for complications, associated with thrombosis and thromboembolism. These flow transients are investigated using phase and time-averaged PIV in a low-volume (about 150 ml) test setup that simulates the pulsatile physiological conditions associated with a 23 mm St. Jude Medical valve. The PIV measurements are accompanied by continuous monitoring of the ventricular and aortic pressures and valve flow rate. Following the valve closure, the leakage flow between the valve leaflets is caused by the pressure buildup across the leaflets, leading to the formation of a regurgitation jet starting from the BMHV B-datum line. As in a typical starting jet, a counter-rotating vortex pair is formed along each leaflet edge and the vorticity sheet is associated with high shear stress that may be result in blood platelet activation. The present investigation demonstrates that the placement of arrays of mm-scale vortex generators near the edges of the leaflets diffuses the vortex sheet and suppresses the formation of these vortices, weakening the local velocity gradients and small-scale vortical structures. Supported by NIH and NSF.

  20. Slow-light vortices in periodic waveguides

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Ha, Sangwoo; Desyatnikov, Anton S.

    2009-01-01

    We reveal that the reduction of the group velocity of light in periodic waveguides is generically associated with the presence of vortex energy flows. We show that the energy flows are gradually frozen for slow-light at the Brillouin zone edge, whereas vortices persist for slow-light states havin...

  1. Bilinear Relative Equilibria of Identical Point Vortices

    DEFF Research Database (Denmark)

    Aref, H.; Beelen, Peter; Brøns, Morten

    2012-01-01

    . In particular, we show that, given q(z)=z 2+η 2, where η is real, there is a unique p(z) of degree n, and a unique value of η 2=A n , such that the zeros of q(z) and p(z) form a relative equilibrium of n+2 point vortices. We show that $A_{n} \\approx\\frac{2}{3}n + \\frac{1}{2}$, as n→∞, where the coefficient of n......A new class of bilinear relative equilibria of identical point vortices in which the vortices are constrained to be on two perpendicular lines, conveniently taken to be the x- and y-axes of a Cartesian coordinate system, is introduced and studied. In the general problem we have m vortices on the y......, obtained using Sturm’s comparison theorem, is that if p(z) satisfies the ODE for a given q(z) with its imaginary zeros symmetric relative to the x-axis, then it must have at least n−m+2 simple, real zeros. For m=2 this provides a complete characterization of all zeros, and we study this case in some detail...

  2. Vortices in superconducting bulk, films and SQUIDs

    Indian Academy of Sciences (India)

    ... realistic shapes like thin and thick strips and disks or thin rectangular plates or films, containing pinned vortices, can be computed within continuum theory by solving an integral equation. A useful example is a thin square with a central hole and a radial slit, used as superconducting quantum interference device (SQUID).

  3. Vorticity Transport on a Rotating Blade

    Science.gov (United States)

    Wojcik, Craig; Buchholz, James

    2012-11-01

    The development of the leading-edge vortex (LEV) is investigated on the suction surface of a rectangular flat plate undergoing a starting rotation in a quiescent fluid for angles of attack between 25 and 45 degrees. For blade aspect ratios of 2 and 4, the LEV is shown to be compact and quasi-stationary at inboard regions of the blade, consistent with the results of some other recent investigations. A salient feature of this flow is a region of opposite-sign vorticity generated on the blade beneath the LEV which is observed to become partially entrained into the LEV. A detailed vorticity transport analysis on the LEV has revealed that the resulting annihilation of vorticity is an important mechanism regulating LEV circulation, and therefore its stability. A parametric study is discussed, which elucidates the roles of shear layer vorticity flux, spanwise flow, vortex tilting, and annihilation on the evolution of LEV circulation with changes in azimuthal position, blade aspect ratio, spanwise position, and Reynolds number. This work was supported by the National Science Foundation (EPSCoR grant EPS1101284), the Air Force Office of Scientific Research (grant FA9550-11-1-0019), and IIHR - Hydroscience & Engineering.

  4. Vortices in theories with flat directions

    NARCIS (Netherlands)

    Achucarro, A; Davis, AC; Pickles, M; Urrestilla, J

    2002-01-01

    In theories with flat directions containing vortices, such as supersymmetric QED, there is a vacuum selection effect in the allowed asymptotic configurations. We explain the role played by gauge fields in this effect and give a simple criterion for determining what vacua will be chosen, namely,

  5. Numerical simulation of pump-intake vortices

    Directory of Open Access Journals (Sweden)

    Rudolf Pavel

    2015-01-01

    Full Text Available Pump pre-swirl or uneven flow distribution in front of the pump can induce pump-intake vortices. These phenomena result in blockage of the impeller suction space, deterioration of efficiency, drop of head curve and earlier onset of cavitation. Real problematic case, where head curve drop was documented, is simulated using commercial CFD software. Computational simulation was carried out for three flow rates, which correspond to three operating regimes of the vertical pump. The domain consists of the pump sump, pump itself excluding the impeller and the delivery pipe. One-phase approach is applied, because the vortex cores were not filled with air during observation of the real pump operation. Numerical simulation identified two surface vortices and one bottom vortex. Their position and strength depend on the pump flow rate. Paper presents detail analysis of the flow field on the pump intake, discusses influence of the vortices on pump operation and suggests possible actions that should be taken to suppress the intake vortices.

  6. Numerical simulation of pump-intake vortices

    Science.gov (United States)

    Rudolf, Pavel; Klas, Roman

    2015-05-01

    Pump pre-swirl or uneven flow distribution in front of the pump can induce pump-intake vortices. These phenomena result in blockage of the impeller suction space, deterioration of efficiency, drop of head curve and earlier onset of cavitation. Real problematic case, where head curve drop was documented, is simulated using commercial CFD software. Computational simulation was carried out for three flow rates, which correspond to three operating regimes of the vertical pump. The domain consists of the pump sump, pump itself excluding the impeller and the delivery pipe. One-phase approach is applied, because the vortex cores were not filled with air during observation of the real pump operation. Numerical simulation identified two surface vortices and one bottom vortex. Their position and strength depend on the pump flow rate. Paper presents detail analysis of the flow field on the pump intake, discusses influence of the vortices on pump operation and suggests possible actions that should be taken to suppress the intake vortices.

  7. Experimental Observations of Ion Phase-Space Vortices

    DEFF Research Database (Denmark)

    Pécseli, Hans; Armstrong, R. J.; Trulsen, J.

    1981-01-01

    Experimental observations of ion phase-space vortices are reported. The ion phase-space vortices form in the region of heated ions behind electrostatic ion acoustic shocks. The results are in qualitative agreement with numerical and analytic studies.......Experimental observations of ion phase-space vortices are reported. The ion phase-space vortices form in the region of heated ions behind electrostatic ion acoustic shocks. The results are in qualitative agreement with numerical and analytic studies....

  8. Cyclones and attractive streaming generated by acoustical vortices.

    Science.gov (United States)

    Riaud, Antoine; Baudoin, Michael; Thomas, Jean-Louis; Bou Matar, Olivier

    2014-07-01

    Acoustical and optical vortices have attracted great interest due to their ability to capture and manipulate particles with the use of radiation pressure. Here we show that acoustical vortices can also induce axial vortical flow reminiscent of cyclones, whose topology can be controlled by adjusting the properties of the acoustical beam. In confined geometry, the phase singularity enables generating "attractive streaming" with the flow directed toward the transducer. This opens perspectives for contactless vortical flow control.

  9. VORTICAL MODEL OF THE WING COVERED WITH CONTINUOUSLY DISTRIBUTED CIRCULATION OF THE VORTICAL LAYER

    Directory of Open Access Journals (Sweden)

    B. L. Artamonov

    2014-01-01

    Full Text Available The linear vortical model ot the final scope of a wing is exsamined. It representis the flat rectangular spatial veil covered with continuously distributed vortical layer. Elements of digitization of a veil are the quadrangular panels laying on its surface. Method, algorithms and the program of calculation of three making vectors of inductive speed from any guided rectangular platform covered with a vortical layer are created. Its intensity linearly changes on the surface of a platform. The decision is received in elementary functions. The numerical way solves the task of a definition of the law of circulation of the attached whirlwinds in scope of a wing and calculation of its aerodynamic characteristics, being based on the accepted vortical model and a hypothesis of flat sections.

  10. Controlled Manipulation of Individual Vortices in a Superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Straver, E.W.J.

    2010-04-05

    We report controlled local manipulation of single vortices by low temperature magnetic force microscope (MFM) in a thin film of superconducting Nb. We are able to position the vortices in arbitrary configurations and to measure the distribution of local depinning forces. This technique opens up new possibilities for the characterization and use of vortices in superconductors.

  11. Severity assessment of pulmonary embolism using dual energy CT - correlation of a pulmonary perfusion defect score with clinical and morphological parameters of blood oxygenation and right ventricular failure

    Energy Technology Data Exchange (ETDEWEB)

    Thieme, Sven F. [Ludwig-Maximilians-Universitaet, Department of Clinical Radiology, Muenchen (Germany); Institut fuer Klinische Radiologie der LMU Muenchen, Muenchen (Germany); Ashoori, Nima; Bamberg, Fabian; Sommer, Wieland H.; Johnson, Thorsten R.C.; Maxien, Daniel; Helck, Andreas D.; Reiser, Maximilian F.; Nikolaou, Konstantin [Ludwig-Maximilians-Universitaet, Department of Clinical Radiology, Muenchen (Germany); Leuchte, Hanno; Becker, Alexander [Ludwig-Maximilians-Universitaet, Department of Medicine I, Muenchen (Germany); Behr, Juergen [Ludwig-Maximilians-Universitaet, Department of Medicine I, Muenchen (Germany); Berufsgenossenschaftliches Universitaetsklinikum Bergmannsheil GmbH Ruhr-Universitaet Bochum, Department of Medicine III, Bochum (Germany)

    2012-02-15

    To correlate a Dual Energy (DE)-based visual perfusion defect scoring system with established CT-based and clinical parameters of pulmonary embolism (PE) severity. In 63 PE patients, DE perfusion maps were visually scored for perfusion defects (P-score). Vascular obstruction was quantified using the Mastora score. Both scores were correlated with short-axis diameters of the right and left ventricle, their ratio (RV/LV ratio), width of the pulmonary trunk, a number of clinical parameters and each other. Univariate and multivariate analyses were performed. Times to generate both scores were recorded. After univariate and multivariate analysis, a significant (p < 0.05) correlation with the P-score was shown for the Mastora score (r = 0.65), RV/LV ratio (r = 0.47), width of the pulmonary trunk (r = 0.26), troponin I (r = 0.43) and PaO{sub 2} (r = -0.50). For the left ventricular diameter, only univariate analysis showed a significant correlation. Mastora score correlated significantly with RV/LV ratio (r = 0.36), width of the pulmonary trunk (r = 0.27), PaO{sub 2} (r = -0.41) and troponin I (r = 0.37). Mean time for generating the P-score was significantly shorter than for the Mastora score. A DE-based P-score correlates with a number of parameters of PE severity. It might be easier and faster to perform than some traditional CT scoring methods for vascular obstruction. (orig.)

  12. Cavopulmonary Anastomosis in a Patient With Arrhythmogenic Right Ventricular Cardiomyopathy With Severe Right Ventricular Dysfunction.

    Science.gov (United States)

    Vaidyanathan, Swaminathan; Kothandam, Sivakumar; Kumar, Rajesh; Indrajith, Sujatha Desai; Agarwal, Ravi

    2017-01-01

    A 26-year-old lady presented with exertional dyspnea, palpitations, central cyanosis, and oxygen saturations of 80% in room air. Her electrocardiogram, echocardiogram, and cardiac magnetic resonance were diagnostic of arrhythmogenic right ventricular dysplasia. There was no documented ventricular arrhythmia or syncopal episodes and Holter recordings were repeatedly normal. Cardiac hemodynamics showed right to left shunt through atrial septal defect, low pulmonary blood flow, normal atrial pressures, and minimally elevated right ventricular end-diastolic pressures. Since her presenting symptoms and cyanosis were attributed to reduced pulmonary blood flow, she underwent off-pump cavopulmonary anastomosis between right superior vena cava and right pulmonary artery. As we intended to avoid the adverse effect of extracorporeal circulation on the myocardial function and pulmonary vasculature, we did not attempt to reduce the size of the atrial septal defect. Her postoperative period was uneventful; oxygen saturation improved to 89% with significant improvement in effort tolerance. At 18-month follow-up, there were no ventricular arrhythmias on surveillance. The clinical presentation of this disease may vary from serious arrhythmias warranting defibrillators and electrical ablations at one end to right ventricular pump failure warranting cardiomyoplasty or right ventricular exclusion procedures at the other end. However, when the presentation was unusual with severe cyanosis through a stretched foramen ovale leading to reduced pulmonary blood flows, Glenn shunt served as a good palliation and should be considered as one of the options in such patients.

  13. Helicity and Vorticity of Pulmonary Arterial Flow in Patients With Pulmonary Hypertension: Quantitative Analysis of Flow Formations.

    Science.gov (United States)

    Schäfer, Michal; Barker, Alex J; Kheyfets, Vitaly; Stenmark, Kurt R; Crapo, James; Yeager, Michael E; Truong, Uyen; Buckner, J Kern; Fenster, Brett E; Hunter, Kendall S

    2017-12-20

    Qualitative and quantitative flow hemodynamic indexes have been shown to reflect right ventricular (RV) afterload and function in pulmonary hypertension (PH). We aimed to quantify flow hemodynamic formations in pulmonary arteries using 4-dimensional flow cardiac magnetic resonance imaging and the spatial velocity derivatives helicity and vorticity in a heterogeneous PH population. Patients with PH (n=35) and controls (n=10) underwent 4-dimensional flow magnetic resonance imaging study for computation of helicity and vorticity in the main pulmonary artery (MPA), the right pulmonary artery, and the RV outflow tract. Helicity and vorticity were correlated with standard RV volumetric and functional indexes along with MPA stiffness assessed by measuring relative area change. Patients with PH had a significantly decreased helicity in the MPA (8 versus 32 m/s2; Pflow hemodynamic character in patients with PH assessed via quantitative analysis is considerably different when compared with healthy and normotensive controls. A strong association between helicity in pulmonary arteries and ventricular-vascular coupling suggests a relationship between the mechanical and flow hemodynamic domains. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  14. Intensity of vortices: from soap bubbles to hurricanes.

    Science.gov (United States)

    Meuel, T; Xiong, Y L; Fischer, P; Bruneau, C H; Bessafi, M; Kellay, H

    2013-12-13

    By using a half soap bubble heated from below, we obtain large isolated single vortices whose properties as well as their intensity are measured under different conditions. By studying the effects of rotation of the bubble on the vortex properties, we found that rotation favors vortices near the pole. Rotation also inhibits long life time vortices. The velocity and vorticity profiles of the vortices obtained are well described by a Gaussian vortex. Besides, the intensity of these vortices can be followed over long time spans revealing periods of intensification accompanied by trochoidal motion of the vortex center, features which are reminiscent of the behavior of tropical cyclones. An analysis of this intensification period suggests a simple relation valid for both the vortices observed here and for tropical cyclones.

  15. Fixed volume particle trace emission for the analysis of left atrial blood flow using 4D Flow MRI.

    Science.gov (United States)

    Gaeta, Stephen; Dyverfeldt, Petter; Eriksson, Jonatan; Carlhäll, Carl-Johan; Ebbers, Tino; Bolger, Ann F

    2017-12-05

    4D Flow MRI has been used to quantify normal and deranged left ventricular blood flow characteristics on the basis of functionally distinct flow components. However, the application of this technique to the atria is challenging due to the presence of continuous inflow. This continuous inflow necessitates plane-based emission of particle traces from the inlet veins, leading to particles that represents different amounts of blood, and related quantification errors. The purpose of this study was to develop a novel fixed-volume approach for particle tracing and employ this method to develop quantitative analysis of 4D blood flow characteristics in the left atrium. 4D Flow MRI data were acquired during free-breathing using a navigator-gated gradient-echo sequence in three volunteers at 1.5T. Fixed-volume particle traces emitted from the pulmonary veins were used to visualize left atrial blood flow and to quantitatively separate the flow into two functionally distinct flow components: Direct flow=particle traces that enter and leave the atrium in one heartbeat, Retained flow=particle traces that enter the atrium and remains there for one cardiac cycle. Flow visualization based on fixed-volume traces revealed that, beginning in early ventricular systole, flow enters the atrium and engages with residual blood volume to form a vortex. In early diastole during early ventricular filling, the organized vortical flow is extinguished, followed by formation of a second transient atrial vortex. Finally, in late diastole during atrial contraction, a second acceleration of blood into the ventricle is seen. The direct and retained left atrial flow components were between 44 and 57% and 43-56% of the stroke volume, respectively. In conclusion, fixed-volume particle tracing permits separation of left atrial blood flow into different components based on the transit of blood through the atrium. Copyright © 2017. Published by Elsevier Inc.

  16. Mimicking graphene with polaritonic spin vortices

    Science.gov (United States)

    Gulevich, Dmitry R.; Yudin, Dmitry

    2017-09-01

    Exploring the properties of strongly correlated systems through quantum simulation with photons, cold atoms, or polaritons represents an active area of research. In fact, the latter sheds light on the behavior of complex systems that are difficult to address in the laboratory or to tackle numerically. In this study, we discuss an analog of graphene formed by exciton-polariton spin vortices arranged into a hexagonal lattice. We show how graphene-type dispersion at different energy scales arises for several types of exciton-polariton spin vortices. In contrast to previous studies of exciton polaritons in artificial lattices, the use of exciton-polariton spin vortex modes offers a richer playground for quantum simulations. In particular, we demonstrate that the sign of the nearest-neighbor coupling strength can be inverted.

  17. Trailing vortices from low speed flyers

    Science.gov (United States)

    Waldman, Rye; Kudo, Jun; Breuer, Kenneth

    2009-11-01

    The structure and strength of the vortex wake behind a airplane or animal flying with a fixed or flapping wing contains valuable information about the aerodynamic load history. However, the amount of vorticity measured in the trailing vortex is not always in agreement with the known lift generated, and the behavior of these vortices at relatively low Reynolds numbers is also not well-understood. We present the results from a series of wind tunnel PIV experiments conducted behind a low-aspect ratio rectangular wing at a chord-Reynolds numbers of 30,000. In addition to wake PIV measurements measured in the cross-stream (Trefftz) plane, we measure the lift and drag directly using a six-axis force-torque transducer. We discuss how vortex size, shape, strength and position vary in time and downstream location, as well as the challenges associated with the use of PIV wake measurements to accurate determine aerodynamic forces.

  18. Statistical mechanics of vortices from field theory

    CERN Document Server

    Kajantie, Keijo; Neuhaus, T; Rajantie, A; Rummukainen, K

    1999-01-01

    We study with lattice Monte Carlo simulations the interactions and macroscopic behaviour of a large number of vortices in the 3-dimensional U(1) gauge+Higgs field theory, in an external magnetic field. We determine non-perturbatively the (attractive or repelling) interaction energy between two or more vortices, as well as the critical field strength H_c, the thermodynamical discontinuities, and the surface tension related to the boundary between the Meissner phase and the Coulomb phase in the type I region. We also investigate the emergence of vortex lattice and vortex liquid phases in the type II region. For the type I region the results obtained are in qualitative agreement with mean field theory, except for small values of H_c, while in the type II region there are significant discrepancies. These findings are relevant for superconductors and some models of cosmic strings, as well as for the electroweak phase transition in a magnetic field.

  19. Statistical mechanics of vortices from field theory

    Science.gov (United States)

    Kajantie, K.; Laine, M.; Neuhaus, T.; Rajantie, A.; Rummukainen, K.

    1999-10-01

    We study with lattice Monte Carlo simulations the interactions and macroscopic behavior of a large number of vortices in the three-dimensional U(1) gauge + Higgs field theory, in an external magnetic field. We determine non-perturbatively the (attractive or repelling) interaction energy between two or more vortices, as well as the critical field strength Hc, the thermodynamical discontinuities, and the surface tension related to the boundary between the Meissner phase and the Coulomb phase in the type I region. We also investigate the emergence of vortex lattice and vortex liquid phases in the type II region. For the type I region the results obtained are in qualitative agreement with mean field theory, except for small values of Hc, while in the type II region there are significant discrepancies. These findings are relevant for superconductors and some models of cosmic strings, as well as for the electroweak phase transition in a magnetic field.

  20. Idiopathic Paroxysmal Ventricular Tachycardia in Infants and Children

    Science.gov (United States)

    Hernandez, Antonio; And Others

    1975-01-01

    Laboratory tests including blood count serum electrolyte measures, and electroencephalograms were performed on seven children ages 1 day to 18 years with recurrent attacks of rapid heart action known as idiopathic paroxysmal ventricular tachycardia. (CL)

  1. Vortical and internal wave shear and strain

    OpenAIRE

    Pinkel, R.

    2014-01-01

    Depth-time records of isopycnal vertical strain have been collected from intensive CTD profiling programs on the research platform (R/P) Floating Instrument Platform (FLIP). The associated vertical wavenumber frequency spectrum of strain, when viewed in an isopycnal-following frame, displays a clear spectral gap at low vertical wavenumber, separating the quasigeostrophic (vortical) strain field and the superinertial internal wave continuum. This gap enables both model and linear-filter-based ...

  2. Automatic measurements of local ventricular parameters using gated blood-pool emission tomography; Extraction automatique des parametres fonctionnels ventriculaires locaux en tomoventriculographie isotopique

    Energy Technology Data Exchange (ETDEWEB)

    Mariano-Goulart, D.; Caderas de Kerleau, C.; Rossi, M. [Centre Hospitalier Universitaire Lapeyronie, 34 - Montpellier (France)

    2005-03-01

    This paper describes a new method designed to improve the accuracy of the assessment of systolic and diastolic parameters from noisy regional time-activity curves, both for the right and the left ventricle. First, we explain how it is possible to derive local time-activity curves from segmented gated-blood pool tomographic acquisitions. The new method is based on the computation of a suitable deformation of a reference time-activity-curve. This paper describes how this reference curve is transformed to approximate the acquired data with a smooth, noise-free time-activity curve from which relevant clinical parameters can be derived. One may remind and illustrate the main results dealing with the validation studies of this new method achieved on simulated data and by comparison with multi-harmonic reconstructions. Last, some clinical examples are proposed to illustrate the potentials of this method. The deformable model used in this paper provides accurate assessment of systolic (time of end systole, amplitude, peak ejection rate) or diastolic parameters (peak filling rate) both for planar and tomographic gated blood pool studies. Further clinical studies are now necessary to compare the results of this model with those achieved with usual multi-harmonic fits, and to evaluate its interest in the assessment of rhythmic heart diseases or in the prognosis of heart failure. (author)

  3. Driven motion of vortices in superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Crabtree, G.W.; Leaf, G.K.; Kaper, H.G.; Vinokur, V.M.; Koshelev, A.E.; Braun, D.W.; Levine, D.M.

    1995-09-01

    The driven motion of vortices in the solid vortex state is analyzed with the time-dependent Ginzburg-Landau equations. In large-scale numerical simulations, carried out on the IBM Scalable POWERparallel (SP) system at Argonne National Laboratory, many hundreds of vortices are followed as they move under the influence of a Lorentz force induced by a transport current in the presence of a planar defect (similar to a twin boundary in YBa{sub 2}CU{sub 3}O{sub 7}). Correlations in the positions and velocities of the vortices in plastic and elastic motion are identified and compared. Two types of plastic motion are observed. Organized plastic motion displaying long-range orientational correlation and shorter-range velocity correlation occurs when the driving forces are small compared to the pinning forces in the twin boundary. Disorganized plastic motion displaying no significant correlation in either the velocities or orientation of the vortex system occurs when the driving and pinning forces axe of the same order.

  4. Jovian Upheaval and its Impact on Vortices

    Science.gov (United States)

    de Pater, Imke

    2009-07-01

    We propose observations of Jupiter with global coverage at highresolution to quantify changes in its atmosphere during andfollowing the global upheaval. Only HST has the capability toobtain images with enough spatial resolution and contrast toextract velocity fields {we will use our newly developedtechnique to accomplish this}, and with WFC3 we can image Jupiterin its entirety in a single exposure. We are in particularinterested in the Red Oval BA: Will the Oval be long-lived,remain red, or turn white again, disappear? Both the merger ofits precursors, and change in color has never before beenwitnessed. The Great Red Spot: This storm system appears todecrease in size and has become rounder, both as derived from itsassociated cloud deck, but also from its potential vorticity, amore dynamically-relevant quantity. How will the GRS evolve? Willit swallow the new vortices detected in amateur images at thissame latitude band? How will this effect the potential vorticity?In addition, we hope to understand Disturbances and stagnationpoints, both of which were detected during the present globalupheaval: are these cyclonic regions, can they spawn anticyclones{as suggested by amateur images}?

  5. Theoretical studies in mesoscale jets and vortices

    Science.gov (United States)

    Radko, Timour

    1997-11-01

    Mesoscale vortices in the mid-ocean are known to move large distances without loss of coherence, preserving their speed and (usually westward) direction. Still open are the questions of how an eddy is able to preserve its structure during many turnaround times and what is the role in this process of the specific perturbations of the circular basic state. To investigate the effect of the rectilinear motion of the isolated eddies, we construct several analytical steady state models and examine the realizability in time of those solutions using the initial-value numerical calculations. To gain a preliminary understanding of the process, we first consider the barotropic f-plane model. It is demonstrated using linearized (about the circular basic state) calculations that for almost any eddy with compact basic velocity we can find a small amplitude disturbance of the first azimuthal harmonic (m=1 mode) that results in the rectilinear motion of an eddy. If such a disturbance is sufficiently small, the vortex can propagate many diameters away from its origin, as shown by a weak non-linear theory. This conclusion is confirmed by the spectral calculations using the full two dimensional vorticity equation. A more realistic representation of the ocean eddies is given by the equivalent-barotropic model, which includes effects of the passive lower layer and the ambient potential vorticity gradient (the beta-effect). Analytical theory is developed to construct a wide class of stable quasi-monopolar vortecies propagating in the westward direction with the supercritical (Usolutions in barotropic and equivalent-barotropic models for all values of the propagation velocity. The numerical spectral calculations, initiated by our analytical solutions, indicate that the (supercritical) vortices initially move with the predicted velocity, but later slow down to the speed of the long planetary waves. The period of time during which an eddy is propagating with its initial velocity is

  6. Regression of electrocardiographic left ventricular hypertrophy or strain is associated with lower incidence of cardiovascular morbidity and mortality in hypertensive patients independent of blood pressure reduction - A LIFE review.

    Science.gov (United States)

    Bang, Casper N; Devereux, Richard B; Okin, Peter M

    2014-01-01

    Cornell product criteria, Sokolow-Lyon voltage criteria and electrocardiographic (ECG) strain (secondary ST-T abnormalities) are markers for left ventricular hypertrophy (LVH) and adverse prognosis in population studies. However, the relationship of regression of ECG LVH and strain during antihypertensive therapy to cardiovascular (CV) risk was unclear before the Losartan Intervention for Endpoint Reduction in Hypertension (LIFE) study. We reviewed findings on ECG LVH regression and strain over time in 9193 hypertensive patients with ECG LVH at baseline enrolled in the LIFE study. The composite endpoint of CV death, nonfatal MI, or stroke occurred in 1096 patients during 4.8±0.9years follow-up. In Cox multivariable models adjusting for randomized treatment, known risk factors including in-treatment blood pressure, and for severity ECG LVH by Cornell product and Sokolow-Lyon voltage, baseline ECG strain was associated with a 33% higher risk of the LIFE composite endpoint (HR. 1.33, 95% CI [1.11-1.59]). Development of new ECG strain between baseline and year-1 was associated with a 2-fold increased risk of the composite endpoint (HR. 2.05, 95% CI [1.51-2.78]), whereas the risk associated with regression or persistence of ECG strain was attenuated and no longer statistically significant (both p>0.05). After controlling for treatment with losartan or atenolol, for baseline Framingham risk score, Cornell product, and Sokolow-Lyon voltage, and for baseline and in-treatment systolic and diastolic blood pressure, 1 standard deviation (SD) lower in-treatment Cornell product was associated with a 14.5% decrease in the composite endpoint (HR. 0.86, 95% CI [0.82-0.90]). In a parallel analysis, 1 SD lower in-treatment Sokolow-Lyon voltage was associated with a 16.6% decrease in the composite endpoint (HR. 0.83, 95% CI [0.78-0.88]). The LIFE study shows that evaluation of both baseline and in-study ECG LVH defined by Cornell product criteria, Sokolow-Lyon voltage criteria or

  7. Baroclinic Vortices in Rotating Stratified Shearing Flows: Cyclones, Anticyclones, and Zombie Vortices

    Science.gov (United States)

    Hassanzadeh, Pedram

    Large coherent vortices are abundant in geophysical and astrophysical flows. They play significant roles in the Earth's oceans and atmosphere, the atmosphere of gas giants, such as Jupiter, and the protoplanetary disks around forming stars. These vortices are essentially three-dimensional (3D) and baroclinic, and their dynamics are strongly influenced by the rotation and density stratification of their environments. This work focuses on improving our understanding of the physics of 3D baroclinic vortices in rotating and continuously stratified flows using 3D spectral simulations of the Boussinesq equations, as well as simplified mathematical models. The first chapter discusses the big picture and summarizes the results of this work. In Chapter 2, we derive a relationship for the aspect ratio (i.e., vertical half-thickness over horizontal length scale) of steady and slowly-evolving baroclinic vortices in rotating stratified fluids. We show that the aspect ratio is a function of the Brunt-Vaisala frequencies within the vortex and outside the vortex, the Coriolis parameter, and the Rossby number of the vortex. This equation is basically the gradient-wind equation integrated over the vortex, and is significantly different from the previously proposed scaling laws that find the aspect ratio to be only a function of the properties of the background flow, and independent of the dynamics of the vortex. Our relation is valid for cyclones and anticyclones in either the cyclostrophic or geostrophic regimes; it works with vortices in Boussinesq fluids or ideal gases, and non-uniform background density gradient. The relation for the aspect ratio has many consequences for quasi-equilibrium vortices in rotating stratified flows. For example, cyclones must have interiors more stratified than the background flow (i.e., super-stratified), and weak anticyclones must have interiors less stratified than the background (i.e., sub-stratified). In addition, this equation is useful to

  8. Visualization of vortical flows in computational fluid dynamics

    Science.gov (United States)

    Volkov, K. N.; Emel'yanov, V. N.; Teterina, I. V.; Yakovchuk, M. S.

    2017-08-01

    The concepts and methods of the visual representation of fluid dynamics computations of vortical flows are studied. Approaches to the visualization of vortical flows based on the use of various definitions of a vortex and various tests for its identification are discussed. Examples of the visual representation of solutions to some fluid dynamics problems related to the computation of vortical flows in jets, channels, and cavities and of the computation of separated flows occurring in flows around bodies of various shapes are discussed.

  9. SIMULATION OF AIRCRAFT CONDENSATION TRAILS AND WAKE VORTICES INTERACTION

    Directory of Open Access Journals (Sweden)

    T. O. Aubakirov

    2015-01-01

    Full Text Available A technique of calculation of aircraft condensation trails (contrails and wake vortices interaction is described. The technique is based on a suitable for real-time applications mathematical model of far wake utilizes the method of discrete vortices. The technique is supplemented by account of the influence of axial velocities in the vortex nucleus on contrail and wake vortex location. Results of calculations of contrails and wake vortices interaction for Il-76 and B-747 aircraft are presented.

  10. Phase shifting profilometry with optical vortices

    Science.gov (United States)

    Sokolenko, B.; Poletaev, D.; Halilov, S.

    2017-11-01

    In this work we review principles and applications of a method of phase shifting profilometry with using of optical vortices imbedded into the probe beam. High spatial resolution caused by vortex phase sensitivity is analysable to retrieve the 2D and 3D shape of optically transparent and reflecting surfaces with exceeding of optical diffraction limit. This method applicable for non-destructive testing of thin films, live cells and biological tissues in real-time regime. Automatic processing of vortex interferograms with vortex phase shift analysis allow to achieve a vertical resolution down to 1,75 nm.

  11. Stability of relative equilibria of three vortices

    DEFF Research Database (Denmark)

    Aref, Hassan

    2009-01-01

    for the three eigenvalues determining the stability, including a new formula for the angular velocity of rotation of a collinear relative equilibrium. A graphical representation of the space of vortex circulations is introduced, and the resultants between various polynomials that enter the problem are used...... involved. The only comprehensive analysis available in the literature, by Tavantzis and Ting [Phys. Fluids 31, 1392 (1988)], is not easy to follow nor is it very physically intuitive. The symmetry between the three vortices is lost in this analysis. A different analysis is given based on explicit formulas...

  12. Interaction of plasma vortices with resonant particles

    DEFF Research Database (Denmark)

    Jovanovic, D.; Pécseli, Hans; Juul Rasmussen, J.

    1990-01-01

    Kinetic effects associated with the electron motion along magnetic field lines in low‐beta plasmas are studied. Using the gyrokinetic description of electrons, a kinetic analog of the reduced magnetohydrodynamic equations is derived, and it is shown that in the strongly nonlinear regime they poss......Kinetic effects associated with the electron motion along magnetic field lines in low‐beta plasmas are studied. Using the gyrokinetic description of electrons, a kinetic analog of the reduced magnetohydrodynamic equations is derived, and it is shown that in the strongly nonlinear regime...... particles. The evolution equations indicate the possibility of excitation of plasma vortices by electron beams....

  13. Observations of Electron Vorticity in the Inner Plasma Sheet

    Science.gov (United States)

    Gurgiolo, C.; Goldstein, M. L.; Vinas, A. F.; Matthaeus, W. H.; Fazakerley, A. N.

    2011-01-01

    From a limited number of observations it appears that vorticity is a common feature in the inner plasma sheet. With the four Cluster spacecraft and the four PEACE instruments positioned in a tetrahedral configuration, for the first time it is possible to directly estimate the electron fluid vorticity in a space plasma. We show examples of electron fluid vorticity from multiple plasma sheet crossings. These include three time periods when Cluster passed through a reconnection ion diffusion region. Enhancements in vorticity are seen in association with each crossing of the ion diffusion region.

  14. Temporal evolution of vorticity staircases in randomly strained two-dimensional vortices

    Science.gov (United States)

    Turner, M. R.

    2014-11-01

    The evolution of a Gaussian vortex subject to a weak-external-random n-fold multipolar strain field is examined using fully nonlinear simulations. The simulations show that at large Reynolds numbers, fine scale steps form at the periphery of the vortex, before merging, generally leaving one large step, which acts as a barrier between the vorticity within the coherent core and the surrounding, well mixed, "surf zone." It is shown for n = 2 that the width and the number of fine scale steps which initially form at the periphery of the vortex is dependent on the strain parameters, but that the range of radial values for which steps initially occur is only dependent on n and the amplitude of the strain field. A criteria is developed which can predict this range of radial values using the linear stability results of Le Dizès ["Non-axisymmetric vortices in two-dimensional flows," J. Fluid Mech. 406, 175 (2000)]. This criteria is based upon the perturbation vorticity needing to be larger than some fraction of the vorticity gradient to flatten the vortex profile. For n = 3 and 4, the radial step range is again predicted, and it is observed that for these higher wavenumbers the long lasting steps are narrower than the n = 2 case. For n = 4 the steps which form are so narrow that they do not persist very long before they are destroyed by the strain field and viscosity.

  15. Observed Effect of Mesoscale Vertical Vorticity on Rotation Sense of Dust Devil-Like Vortices in an Urban Area

    OpenAIRE

    Fujiwara, Chusei; Yamashita, Kazuya; Fujiyoshi, Yasushi

    2012-01-01

    Dust devil-like vortices were detected by a three-dimensional scanning coherent Doppler lidar (3D-CDL) in an urban area of Sapporo, Japan, from April 2005 to July 2007. A total of 57 strong, dust devil-like vortices with vertical vorticity exceeding 0.1 s^[-1] were detected in 8 days of the observation period and were associated with a convective cell (fish net) pattern of wind fields detected by the 3D-CDL. The observed vortices had both rotation senses for 7 days. However, all of 7 dust dev...

  16. Premature Ventricular Contractions (PVCs)

    Science.gov (United States)

    ... Premature ventricular contractions (PVCs) Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  17. Right ventricular dysfunction affects survival after surgical left ventricular restoration.

    Science.gov (United States)

    Couperus, Lotte E; Delgado, Victoria; Palmen, Meindert; van Vessem, Marieke E; Braun, Jerry; Fiocco, Marta; Tops, Laurens F; Verwey, Harriëtte F; Klautz, Robert J M; Schalij, Martin J; Beeres, Saskia L M A

    2017-04-01

    Several clinical and left ventricular parameters have been associated with prognosis after surgical left ventricular restoration in patients with ischemic heart failure. The aim of this study was to determine the prognostic value of right ventricular function. A total of 139 patients with ischemic heart failure (62 ± 10 years; 79% were male; left ventricular ejection fraction 27% ± 7%) underwent surgical left ventricular restoration. Biventricular function was assessed with echocardiography before surgery. The independent association between all-cause mortality and right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain was assessed. The additive effect of multiple impaired right ventricular parameters on mortality also was assessed. Baseline right ventricular fractional area change was 42% ± 9%, tricuspid annular plane systolic excursion was 18 ± 3 mm, and right ventricular longitudinal peak systolic strain was -24% ± 7%. Within 30 days after surgery, 15 patients died. Right ventricular fractional area change (hazard ratio, 0.93; 95% confidence interval, 0.88-0.98; P right ventricular longitudinal peak systolic strain (hazard ratio, 1.15; 95% confidence interval, 1.05-1.26; P Right ventricular function was impaired in 21%, 20%, and 27% of patients on the basis of right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain, respectively. Any echocardiographic parameter of right ventricular dysfunction was present in 39% of patients. The coexistence of several impaired right ventricular parameters per patient was independently associated with increased 30-day mortality (hazard ratio, 2.83; 95% confidence interval, 1.64-4.87, P right ventricular systolic dysfunction is independently associated with increased mortality in patients with ischemic heart failure undergoing surgical left

  18. Melt pool vorticity in deep penetration laser material welding

    Indian Academy of Sciences (India)

    In the present study, the vorticity of melt motion in the keyhole and weld pool has been evaluated in case of high power CO2 laser beam welding. The circulation of vorticity is obtained as a function of Reynolds number for a given keyhole volume which is linked to Mach number variation. The shear stress and thermal fluxes ...

  19. Melt pool vorticity in deep penetration laser material welding

    Indian Academy of Sciences (India)

    Abstract. In the present study, the vorticity of melt motion in the keyhole and weld pool has been evaluated in case of high power CO2 laser beam welding. The circulation of vorticity is obtained as a function of Reynolds number for a given keyhole volume which is linked to Mach number variation. The shear stress and ther-.

  20. Diffused vorticity approach to the oscillations of a rotating Bose ...

    Indian Academy of Sciences (India)

    Abstract. The collective modes of a rotating Bose–Einstein condensate confined in an attractive quadratic plus quartic trap are investigated. Assuming the presence of a large number of vortices we apply the diffused vorticity approach to the system. We then use the sum rule technique for the calculation of collective ...

  1. Diffused vorticity approach to the oscillations of a rotating Bose ...

    Indian Academy of Sciences (India)

    The collective modes of a rotating Bose-Einstein condensate confined in an attractive quadratic plus quartic trap are investigated. Assuming the presence of a large number of vortices we apply the diffused vorticity approach to the system. We then use the sum rule technique for the calculation of collective frequencies, ...

  2. Gyrofluid potential vorticity equation and turbulent equipartion states

    DEFF Research Database (Denmark)

    Madsen, Jens; Juul Rasmussen, Jens; Naulin, Volker

    2015-01-01

    An equation governing potential vorticity in a magnetized plasmas is derived. The equation is analogous to Ertel's theorem. In the long wave-length limit the potential vorticity equals the ratio of the gyro-frequency plus the E × B- and diamagnetic polarization densities to the particle density...

  3. Direct observation of rectified motion of vortices by Lorentz microscopy

    Indian Academy of Sciences (India)

    Abstract. We have investigated the vortex dynamics for the 'ratchet' operation in a niobium superconductor via a direct imaging of Lorentz microscopy. We directly observe one-directional selective motion of field-gradient-driven vortices along fabricated channels. This results from the rectification of vortices in a spatially ...

  4. Direct observation of rectified motion of vortices by Lorentz microscopy

    Indian Academy of Sciences (India)

    We have investigated the vortex dynamics for the `ratchet' operation in a niobium superconductor via a direct imaging of Lorentz microscopy. We directly observe one-directional selective motion of field-gradient-driven vortices along fabricated channels. This results from the rectification of vortices in a spatially asymmetric ...

  5. Vorticity and helicity in relativistic heat-conducting fluid

    Science.gov (United States)

    Prasad, G.

    2017-12-01

    The evolution of heat-conducting fluid described by a pair of Maxwell-like equations is used to construct thermal-fluid helicity and thermal-helicity currents. These currents are found to be dissipative. It is shown that the magnetic part of the particle vorticity two-form is a thermal-fluid vorticity flux vector field composed of a linear combination of the fluid’s vorticity and a spacelike twist of heat flow lines. Heat flow lines are non-geodesic because of the interplay between gravitation and the entropy entrainment in a system composed of a heat-conducting fluid which is in state of rapid differential rotation and far from equilibrium. In general, alignment of the heat flux vector with that of the fluid’s vorticity leads to non-conservation of thermal-fluid vorticity flux in both a thermal-fluid flux tube and a stream tube. It is demonstrated that the twist of the fluid’s vortex lines is caused by the heat flow along the fluid’s vorticity vector in the case of an axisymmetric stationary differentially rotating heat-conducting fluid configuration. In this case, dissipation of thermal-fluid vorticity flux along the flux tube is caused by coupled effects of the fluid’s vorticity magnitude, thermal resistivity and entropy entrainment.

  6. Potential vorticity field in the Bay of Bengal during southwest monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Rao, D.P.

    theta), potential vorticity distribution is complex due to wind and freshwater forcings. The beta -effect dominates the potential vorticity field on 26.9 sigma theta isopycnal. The field of potential vorticity closely follows that of circulation...

  7. Helical vortices: linear stability analysis and nonlinear dynamics

    Science.gov (United States)

    Selçuk, C.; Delbende, I.; Rossi, M.

    2018-02-01

    We numerically investigate, within the context of helical symmetry, the dynamics of a regular array of two or three helical vortices with or without a straight central hub vortex. The Navier–Stokes equations are linearised to study the instabilities of such basic states. For vortices with low pitches, an unstable mode is extracted which corresponds to a displacement mode and growth rates are found to compare well with results valid for an infinite row of point vortices or an infinite alley of vortex rings. For larger pitches, the system is stable with respect to helically symmetric perturbations. In the nonlinear regime, we follow the time-evolution of the above basic states when initially perturbed by the dominant instability mode. For two vortices, sequences of overtaking events, leapfrogging and eventually merging are observed. The transition between such behaviours occurs at a critical ratio involving the core size and the vortex-separation distance. Cases with three helical vortices are also presented.

  8. Decay of high order optical vortices in anisotropic nonlinear optical media

    DEFF Research Database (Denmark)

    Mamaev, A.V.; Saffman, M.; Zozulya, A.A.

    1997-01-01

    We present an experimental and theoretical study of the decay of high order optical vortices in media with an anisotropic nonlocal nonlinearity. Vortices with charge n decay into an aligned array of n vortices of unit charge.......We present an experimental and theoretical study of the decay of high order optical vortices in media with an anisotropic nonlocal nonlinearity. Vortices with charge n decay into an aligned array of n vortices of unit charge....

  9. Cubic nonlinear Schroedinger equation with vorticity

    Energy Technology Data Exchange (ETDEWEB)

    Caliari, M; Morato, L M; Zuccher, S [Dipartimento di Informatica, Universita di Verona, Ca' Vignal 2, Strada Le Grazie 15, 37134 Verona (Italy); Loffredo, M I [Dipartimento di Scienze Matematiche ed Informatiche, Universita di Siena, Pian dei Mantellini 44, 53100 Siena (Italy)], E-mail: marco.caliari@univr.it, E-mail: loffredo@unisi.it, E-mail: laura.morato@univr.it, E-mail: zuccher@sci.univr.it

    2008-12-15

    In this paper, we introduce a new class of nonlinear Schroedinger equations (NLSEs), with an electromagnetic potential (A,{phi}), both depending on the wavefunction {psi}. The scalar potential {phi} depends on |{psi}|{sup 2}, whereas the vector potential A satisfies the equation of magnetohydrodynamics with coefficient depending on {psi}. In Madelung variables, the velocity field comes to be not irrotational in general and we prove that the vorticity induces dissipation, until the dynamical equilibrium is reached. The expression of the rate of dissipation is common to all NLSEs in the class. We show that they are a particular case of the one-particle dynamics out of dynamical equilibrium for a system of N identical interacting Bose particles, as recently described within stochastic quantization by Lagrangian variational principle. The cubic case is discussed in particular. Results of numerical experiments for rotational excitations of the ground state in a finite two-dimensional trap with harmonic potential are reported.

  10. Dipole vortices in the Great Australian Bight

    DEFF Research Database (Denmark)

    Cresswell, George R.; Lund-Hansen, Lars C.; Nielsen, Morten Holtegaard

    2015-01-01

    Shipboard measurements from late 2006 made by the Danish Galathea 3 Expedition and satellite sea surface temperature images revealed a chain of cool and warm mushroom' dipole vortices that mixed warm, salty, oxygen-poor waters on and near the continental shelf of the Great Australian Bight (GAB......) with cooler, fresher, oxygen-rich waters offshore. The alternating jets' flowing into the mushrooms were directed mainly northwards and southwards and differed in temperature by only 1.5 degrees C; however, the salinity difference was as much as 0.5, and therefore quite large. The GAB waters were slightly...... denser than the cooler offshore waters. The field of dipoles evolved and distorted, but appeared to drift westwards at 5km day-1 over two weeks, and one new mushroom carried GAB water southwards at 7km day(-1). Other features encountered between Cape Leeuwin and Tasmania included the Leeuwin Current...

  11. Potential vorticity patterns in Mediterranean "hurricanes"

    Science.gov (United States)

    Miglietta, M. M.; Cerrai, D.; Laviola, S.; Cattani, E.; Levizzani, V.

    2017-03-01

    The potential vorticity (PV) anomalies due to the intrusion of dry stratospheric air and those generated by the tropospheric diabatic latent heating are qualitatively analyzed for five Mediterranean tropical-like cyclones (also known as Medicanes). Model simulations show the presence of an upper level PV streamer in the early stages of the cyclone, located on the left exit of a jet stream, and a middle-low level PV anomaly generated by the convection developing around the low-level vortex. In the mature stage, the upper level PV anomaly around the cyclone evolves differently for each case and appears somehow dependent on the lifetime. Only for the 2006 Medicane, the PV anomalies form an intense PV tower extending continuously from the lower troposphere to the lower stratosphere.

  12. Vortices and hysteresis in a rotating Bose-Einstein condensate with anharmonic confinement

    DEFF Research Database (Denmark)

    Jackson, A.D.; Kavoulakis, G.M.

    2004-01-01

    Vortices; Bose-Einstein condensation; phase diagrams; phase transformation Udgivelsesdato: 4 August......Vortices; Bose-Einstein condensation; phase diagrams; phase transformation Udgivelsesdato: 4 August...

  13. Structures of the vorticity tube segment in turbulence

    Science.gov (United States)

    Wang, Lipo

    2012-04-01

    To address the geometrical properties of the turbulent velocity vector field, a new concept named streamtube segment has been developed recently [L. Wang, "On properties of fluid turbulence along streamlines," J. Fluid Mech. 648, 183-203 (2010), 10.1017/S0022112009993041]. According to the vectorial topology, the entire velocity field can be partitioned into the so-called streamtube segments, which are organized in a non-overlapping and space-filling manner. In principle, properties of turbulent fields can be reproduced from those of the decomposed geometrical units with relatively simple structures. A similar idea is implemented to study the turbulent vorticity vector field using the vorticity tube segment structure. Differently from the conventional vortex tubes, vorticity tube segments are space-filling and can be characterized by non-arbitrary parameters, which enables a more quantitative description rather than just an illustrative explanation of turbulence behaviors. From analyzing the direct numerical simulation data, the topological and dynamical properties of vorticity tube segments are explored. The characteristic parameters have strong influence on some conditional statistics, such as the enstrophy production and the probability density function of vorticity stretching. Consequently the common knowledge in turbulence dynamics that vorticity are more stretched than compressed need to be rectified in the vorticity tube segment context.

  14. Heat transfer enhancement using tip and junction vortices

    Science.gov (United States)

    Gentry, Mark Cecil

    1998-10-01

    Single-phase convective heat transfer can be enhanced by modifying the heat transfer surface to passively generate streamwise vortices. The swirling flow of the vortices modifies the temperature field, thinning the thermal boundary layer and increasing surface convection. Tip vortices generated by delta wings and junction vortices generated by hemispherical protuberances were studied in laminar flat-plate and developing channel flows. Local and average convective measurements were obtained, and the structure of the vortices was studied using quantitative flow visualization and vortex strength measurements. The pressure drop penalty associated with the heat transfer enhancement was also investigated. Tip vortices generated by delta wings enhanced local convection by as much as 300% over a flat-plate boundary layer flow. Vortex strength increased with Reynolds number based on chord length, wing aspect ratio, and wing angle of attack. As the vortices were advected downstream, they decayed because of viscous interactions. In the developing channel flow, tip vortices produced a significant local heat transfer enhancement on both sides of the channel. The largest spatially averaged heat transfer enhancement was 55%; it was accompanied by a 100% increase in the pressure drop relative to the same channel flow with no delta-wing vortex generator. Junction vortices created by hemispherical surface protuberances provided local heat transfer enhancements as large as 250%. Vortex strength increased with an increasing ratio of hemisphere radius to local boundary layer thickness on a flat plate. In the developing channel flows, heat transfer enhancements were observed on both sides of the channel. The largest spatially averaged heat transfer enhancement was 50%; it was accompanied by a 90% pressure drop penalty relative to the same channel flow with no hemispherical vortex generator. This research is important in compact heat exchanger design. Enhancing heat transfer can lead to

  15. Thermal Convection and Emergence of Isolated Vortices in Soap Bubbles

    Science.gov (United States)

    Seychelles, F.; Amarouchene, Y.; Bessafi, M.; Kellay, H.

    2008-04-01

    A novel thermal convection cell consisting of half a soap bubble heated at the equator is introduced to study thermal convection and the movement of isolated vortices. The soap bubble, subject to stratification, develops thermal convection at its equator. A particular feature of this cell is the emergence of isolated vortices. These vortices resemble hurricanes or cyclones and similarities between our observed structures and these natural objects are found. This is brought forth through a study of the mean square displacement of these objects showing signs of superdiffusion.

  16. Thermal convection and emergence of isolated vortices in soap bubbles.

    Science.gov (United States)

    Seychelles, F; Amarouchene, Y; Bessafi, M; Kellay, H

    2008-04-11

    A novel thermal convection cell consisting of half a soap bubble heated at the equator is introduced to study thermal convection and the movement of isolated vortices. The soap bubble, subject to stratification, develops thermal convection at its equator. A particular feature of this cell is the emergence of isolated vortices. These vortices resemble hurricanes or cyclones and similarities between our observed structures and these natural objects are found. This is brought forth through a study of the mean square displacement of these objects showing signs of superdiffusion.

  17. Synthesis and analysis of linear and nonlinear acoustical vortices.

    Science.gov (United States)

    Marchiano, Régis; Thomas, Jean-Louis

    2005-06-01

    Acoustical screw dislocations are synthesized in various configurations with a versatile experimental setup. The experimental setup is based on the inverse filter technique and allows one to synthesize one or more acoustical vortices with a chosen width, position, and topological charge. An interesting feature of this experimental facility to study screw dislocation behavior is the direct measurement in amplitude and phase. This characteristic is used to develop an original method of decomposition of an acoustical vortex field in order to analyze the acoustical vortices. Moreover, the behaviors of two acoustical vortices of the same or opposite charge have been studied experimentally and compared to theoretical laws.

  18. Experimental Study of the Interaction between Vortices in Electrolytic Solutions

    Science.gov (United States)

    Izaguirre, E. W.

    1996-11-01

    The interaction between vortices and their structure are analyzed in a system of three vortices in electrolytic solutions using crosed electric and magnetic fields in a square tray. The flow pattern and the speed field are obtained using image techniques and anemometry. The experiment is repeated for different strengths of the magnetic and electric fields, and thickness of the fluid layer. Self oscillations, coupling and competition between vortices are observed. A model of the system is presented and numerical results contrasted with the experimental data.

  19. Left and right ventricular diastolic function in hemodialysis patients

    Directory of Open Access Journals (Sweden)

    Rudhani Ibrahim

    2010-01-01

    Full Text Available The aim of this prospective study was the assessment of left ventricular and right ventricular diastolic function in patients on hemodialysis (HD and the correlation of this func-tion with the duration of HD. The study included 42 patients (22 females and 20 males with chro-nic renal failure (CRF, treated with HD, and 40 healthy subjects (24 females and 16 males with no history of cardiovascular disease and with normal renal function, who constituted the control group. The groups were matched for age and sex. All study patients and control subjects under-went detailed history taking and physical examination. They also underwent electrocardiogram, echocardiography and biochemical and hematological blood analyses. Significant differences were noted between the two groups in the two-dimensional and M-mode echocardiography findings concerning aortic root dimension, transverse diameter of the left atrium, thickness of the inter-ventricular septum, thickness of the left ventricular posterior wall, left ventricular diastolic diameter, left ventricular systolic diameter, shortening fraction, ejection fraction as well as findings from the pulse Doppler study, including E wave, A wave, E/A ratio, deceleration time of E wave (DT-E, acceleration time of E wave (AT-E, tricuspid E and A waves (E tr and A tr and E tr /A tr , ratio. There were significant changes in HD patients without arterial hypertension as well in the control group subjects. Our study suggests that the left ventricular and left atrial dimensions as well as the left ventricular wall thickness are augmented in patients with CRF treated with HD compared with the control group. Additionally, the left and right ventricular diastolic function is also reduced in these patients. These differences were also noted in patients with CRF without arterial hypertension. Left ventricular diastolic dysfunction had no correlation with the duration of HD.

  20. Equivariant Verlinde Formula from Fivebranes and Vortices

    Science.gov (United States)

    Gukov, Sergei; Pei, Du

    2017-10-01

    We study complex Chern-Simons theory on a Seifert manifold M 3 by embedding it into string theory. We show that complex Chern-Simons theory on M 3 is equivalent to a topologically twisted supersymmetric theory and its partition function can be naturally regularized by turning on a mass parameter. We find that the dimensional reduction of this theory to 2d gives the low energy dynamics of vortices in four-dimensional gauge theory, the fact apparently overlooked in the vortex literature. We also generalize the relations between (1) the Verlinde algebra, (2) quantum cohomology of the Grassmannian, (3) Chern-Simons theory on {Σ× S^1} and (4) index of a spin c Dirac operator on the moduli space of flat connections to a new set of relations between (1) the "equivariant Verlinde algebra" for a complex group, (2) the equivariant quantum K-theory of the vortex moduli space, (3) complex Chern-Simons theory on {Σ × S^1} and (4) the equivariant index of a spin c Dirac operator on the moduli space of Higgs bundles.

  1. Artificial ice using superconducting vortices (Conference Presentation)

    Science.gov (United States)

    Trastoy Quintela, Juan; Malnou, Maxime; Ulysse, Christian; Bernard, Rozenn; Bergeal, Nicolas; Faini, Giancarlo; Lesueur, Jerome; Briatico, Javier; Villegas, Javier E.

    2016-10-01

    We use magnetic flux quanta (superconducting vortices) on artificial energy landscapes (pinning arrays) to create a new type of artificial ice. This vortex ice shows unusual temperature effects that offer new possibilities in the study of ice systems. We have investigated the matching of the flux lattice to pinning arrays that present geometrical frustration. The pinning arrays are fabricated on YBCO films using masked O+ ion irradiation. The details of the magneto-resistance imply that the flux lattice organizes into a vortex ice. The absence of history-dependent effects suggests that the vortex ice is highly ordered. Due to the technique used for the artificial energy landscape fabrication, we have the ability to change the pinning array geometry using temperature as a control knob. In particular we can switch the geometrical frustration on and off, which opens the door to performing a new type of annealing absent in other artificial ice systems. * Work supported by the French ANR "MASTHER", and the Fundación Barrié (Galicia, Spain)

  2. Analytical BPS Maxwell-Higgs Vortices

    Directory of Open Access Journals (Sweden)

    R. Casana

    2014-01-01

    Full Text Available We have established a prescription for the calculation of analytical vortex solutions in the context of generalized Maxwell-Higgs models whose overall dynamics is controlled by two positive functions of the scalar field, namely, fϕ and wϕ. We have also determined a natural constraint between these functions and the Higgs potential Uϕ, allowing the existence of axially symmetric Bogomol'nyi-Prasad-Sommerfield (BPS solutions possessing finite energy. Furthermore, when the generalizing functions are chosen suitably, the nonstandard BPS equations can be solved exactly. We have studied some examples, comparing them with the usual Abrikosov-Nielsen-Olesen (ANO solution. The overall conclusion is that the analytical self-dual vortices are well-behaved in all relevant sectors, strongly supporting the consistency of the respective generalized models. In particular, our results mimic well-known properties of the usual (numerical configurations, as localized energy density, while contributing to the understanding of topological solitons and their description by means of analytical methods.

  3. EFFECTS OF DUST FEEDBACK ON VORTICES IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Wen; Liang, Edison [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States); Li, Hui; Li, Shengtai [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lubow, Stephen, E-mail: wf5@rice.edu [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2014-11-10

    We carried out two-dimensional, high-resolution simulations to study the effect of dust feedback on the evolution of vortices induced by massive planets in protoplanetary disks. Various initial dust to gas disk surface density ratios (0.001-0.01) and dust particle sizes (Stokes number 4 × 10{sup –4}-0.16) are considered. We found that while dust particles migrate inward, vortices are very effective at collecting them. When dust density becomes comparable to gas density within the vortex, a dynamical instability is excited and it alters the coherent vorticity pattern and destroys the vortex. This dust feedback effect is stronger with a higher initial dust/gas density ratio and larger dust grain. Consequently, we found that the disk vortex lifetime can be reduced up to a factor of 10. We discuss the implications of our findings on the survivability of vortices in protoplanetary disks and planet formation.

  4. On the definition of a moist-air potential vorticity

    CERN Document Server

    Marquet, Pascal

    2014-01-01

    A new potential vorticity is derived by using a specific entropy formulation expressed in terms of a moist-air entropy potential temperature. The new formulation is compared with Ertel's version and with others based on virtual and equivalent potential temperatures. The new potential vorticity is subject to conservative properties ensured by the Second Law applied to the moist-air material derivatives. It is shown that the upper tropospheric and stratospheric (dry) structures are nearly the same as those obtained with Ertel's component. Moreover, new structures are observed in the low troposphere, with negative values associated with moist frontal regions. The negative values are observed in the frontal regions where slantwise convection instabilities may take place, but they are smaller than those observed with the equivalent potential vorticity. The main purpose of the article is to diagnose the behaviour of the new potential vorticity from numerical output generated by the ARPEGE NWP model, with the help o...

  5. The decay of longitudinal vortices shed from airfoil vortex generators

    Science.gov (United States)

    Wendt, Bruce J.; Reichert, Bruce A.; Foster, Jeffry D.

    1995-01-01

    An experimental study is conducted to examine the crossplane structure and streamwise decay of vortices shed from airfoil-type vortex generators. The vortex generators are set in a counter-rotating array spanning the full circumference of a straight pipe. The span of the vortex generators above the duct surface, h, is approximately equal to the local turbulent boundary layer thickness, delta. Measurement of three-component mean flow velocity in downstream crossplanes are used to characterize the structure of the shed vortices. Measurements in adjacent crossplanes (closely spaced along the streamwise coordinate) characterize the interaction and decay of the embedded vortices. A model constructed by the superposition of Oseen vortices is compared to the data for one test case.

  6. A numerical study of vorticity-enhanced heat transfer

    Science.gov (United States)

    Wang, Xiaolin; Alben, Silas

    2012-11-01

    The Glezer lab at Georgia Tech has found that vorticity produced by vibrated reeds can improve heat transfer in electronic hardware. Vortices enhance forced convection by boundary layer separation and thermal mixing in the bulk flow. In this work, we simulate the heat transfer process in a 3-dimensional plate-fin heat sink. We propose a simplified model by considering flow and temperature in a 2-D channel, and extend the model to the third dimension using a 1-D heat fin model. We simulate periodically steady-state solutions. We determine how the global Nusselt number is increased, depending on the vortices' strengths and spacings, in the parameter space of Reynolds and Peclet numbers. We find a surprising spatial oscillation of the local Nusselt number due to the vortices. Support from NSF-DMS grant 1022619 is acknowledged.

  7. Image simulations of kinked vortices for transmission electron microscopy

    DEFF Research Database (Denmark)

    Beleggia, Marco; Pozzi, G.; Tonomura, A.

    2010-01-01

    We present an improved model of kinked vortices in high-Tc superconductors suitable for the interpretation of Fresnel or holographic observations carried out with a transmission electron microscope. A kinked vortex is composed of two displaced half-vortices, perpendicular to the film plane......, connected by a horizontal flux-line in the plane, resembling a connecting Josephson vortex (JV) segment. Such structures may arise when a magnetic field is applied almost in the plane, and the line tension of the fluxon breaks down under its influence. The existence of kinked vortices was hinted in earlier...... observations of high-Tc superconducting films, where the Fresnel contrast associated with some vortices showed a dumbbell like appearance. Here, we show that under suitable conditions the JV segment may reveal itself in Fresnel imaging or holographic phase mapping in a transmission electron microscope....

  8. A Generalized Form of Lait's Modified Potential Vorticity.

    Science.gov (United States)

    Müller, Rolf; Günther, Gebhard

    2003-09-01

    Ertel's potential vorticity P is in widespread use as a diagnostic of dynamical processes in the stratosphere. For a variety of applications, however, the exponential increase of P with altitude is problematic. For this reason, Lait proposed a modified potential vorticity L, where a physically meaningful scaling is introduced that removes much of the altitude dependence of P. Here a generalized form of L is proposed by introducing an additional degree of freedom in the scaling. This generalized modified potential vorticity g possesses the same conservation properties as L itself and as the classic potential vorticity P but can be adjusted more closely to the specific situation under investigation. Comparison, over a large altitude range in the stratosphere, of fields of g with dynamical measures of the polar vortex edge and with observations of the long-lived trace gas N2O shows that g constitutes a more intuitively interpretable quantity than L.

  9. Fractional vortices in the XY model with $\\pi$ bonds

    OpenAIRE

    Kulkarni, R. V.; Almaas, E.; Fisher, K. D.; Stroud, D.

    2000-01-01

    We define a new set of excitations in the XY model which we call ``fractional vortices''. In the frustrated XY model containing $\\pi$ bonds, we make the ansatz that the ground state configurations can be characterized by pairs of oppositely charged fractional vortices. For a chain of $\\pi$ bonds, the ground state energy and the phase configurations calculated on the basis of this ansatz agree well with the results from direct numerical simulations. Finally, we discuss the possible connection ...

  10. Measurement of Entrained Air Bubbles and Vortices in Breaking Waves

    OpenAIRE

    大塚, 淳一; 渡部, 靖憲; Junichi, Otsuka; Yasunori, Watanabe; 北海道大学大学院工学研究科; School of Engineering, Hokkaido University

    2007-01-01

    Breaking waves produce numbers of vortices through a jet splashing process and also entrain many air bubbles, forming complicated air-water two-phase turbulent flow field in a surf zone. In this research, a simultaneous velocity measurement technique of water and bubble flows in breaking waves is developed for characterizing water-bubble interactions within vortices in a surf zone. The bubbles and neutral buoyant tracers are separately recorded by two different digital video cameras on the ba...

  11. Magneto-static vortices in two dimensional Abelian gauge theories

    OpenAIRE

    Bellazzini, J.; Bonanno, C.; Siciliano, G

    2008-01-01

    We study the existence of vortices of the Klein-Gordon-Maxwell equations in the two dimensional case. In particular we find sufficient conditions for the existence of vortices in the magneto-static case, i.e when the electric potential $\\phi=0$. This result, due to the lack of suitable embedding theorems for the vector potential $\\A$ is achieved with the help of a penalization method.

  12. Simulating living organisms with populations of point vortices

    Energy Technology Data Exchange (ETDEWEB)

    Schmieder, R.W.

    1995-07-01

    The author has found that time-averaged images of small populations of point vortices can exhibit motions suggestive of the behavior of individual organisms. As an example, the author shows that collections of point vortices confined in a box and subjected to heating can generate patterns that are broadly similar to interspecies defense in certain sea anemones. It is speculated that other simple dynamical systems can be found to produce similar complex organism-like behavior.

  13. Secondary vortex formation in ring vortices in free jets

    Science.gov (United States)

    Schneider, E. M.

    1980-10-01

    Secondary vortex formation is examined as a basic component of the turbulent condition of vortex and laminar currents. Dyed fluid ring vortices are used to investigate formation moving against an object and in an unobstructed environment. Part of the vortex structure of jets can be explained by means of secondary vortices, and the sound spectrum both of a single turbulent vortex and of jets is influenced by secondary vortex formation.

  14. Onset of Vortices in Thin Superconducting Strips and Wires

    CERN Document Server

    Aranson, I S; Shapiro, B Y

    1994-01-01

    Spontaneous nucleation and the consequent penetration of vortices into thin superconducting films and wires, subjected to a magnetic field, can be considered as a nonlinear stage of primary instability of the current-carrying superconducting state. The development of the instability leads to the formation of a chain of vortices in strips and helicoidal vortex lines in wires. The boundary of instability was obtained analytically. The nonlinear stage was investigated by simulations of the time-dependent generalized Ginzburg-Landau equation.

  15. Quantum vortices in systems obeying a generalized exclusion principle.

    Science.gov (United States)

    Kaniadakis, G; Scarfone, A M

    2001-08-01

    The paper deals with a planar particle system obeying a generalized exclusion principle (EP) and governed, in the mean field approximation, by a nonlinear Schrödinger equation. We show that the EP involves a mathematically simple and physically transparent mechanism, which allows the genesis of quantum vortices in the system. We obtain in a closed form the shape of the vortices and investigate its main physical properties.

  16. The role of vortices in animal locomotion in fluids

    Directory of Open Access Journals (Sweden)

    Dvořák R.

    2014-12-01

    Full Text Available The aim of this paper is to show the significance of vortices in animal locomotion in fluids on two deliberately chosen examples. The first example concerns lift generation by bird and insect wings, the second example briefly mentiones swimming and walking on water. In all the examples, the vortices generated by the moving animal impart the necessary momentum to the surrounding fluid, the reaction to which is the force moving or lifting the animal.

  17. Factors influencing left ventricular hypertrophy in children and adolescents with or without family history of premature myocardial infarction

    Directory of Open Access Journals (Sweden)

    Seyyed Mohsen Hosseini

    2014-01-01

    Result : The results showed that among the studied variables, gender, age, body mass index, and blood pressure were associated with the left ventricular hypertrophy. Conclusion: Considering the results and previous studies in this field, it was observed that left ventricular hypertrophy exists at early ages, which is very dangerous and can lead to heart diseases at early ages. Factors such as being overweight, having high blood pressure, and being male cause left ventricular hypertrophy and lead to undiagnosable heart diseases.

  18. Static and dynamic properties of heavily doped quantum vortices

    Science.gov (United States)

    Pshenichnyuk, I. A.

    2017-10-01

    Quantum vortices in superfluids may capture matter and deposit it inside their core. By doping vortices with foreign particles one can effectively visualize them and study them experimentally. To acquire a better understanding of the interaction between quantum vortices and matter, and clarify the details of recent experiments, the properties of doped vortices are investigated here theoretically in the regimes where the doping mass becomes close to the total mass of superfluid particles forming a vortex. Such formations are dynamically stable and, possessing both vorticity and enhanced inertia, demonstrate properties that are different from the pure vortex case. The goal of this paper is to define and investigate the universal aspects of heavily doped vortex behavior, which can be realized in different types of quantum mixtures. The proposed 3D model is based on a system of coupled semiclassical matter wave equations that are solved numerically in a wide range of physical parameters. The size, geometry and binding energy of dopants in different regimes are discussed. The coupled motion of a vortex–dopant complex and decoupling conditions are studied. The reconnection of vortices, taken as an example of a fundamental process responsible for the evolution of a quantum turbulent state, is modeled to illustrate the difference between the light and heavy doping cases.

  19. Orientation and circulation of vortices in a turbulent boundary layer

    Science.gov (United States)

    Gao, Qi; Ortiz-Dueñas, Cecilia; Longmire, Ellen

    2007-11-01

    The strengths of individual vortices are important in determining the generation and development of surrounding vortices in turbulent boundary layers. The dual-plane PIV data at z^+ = 110 and z/δ = 0.53 in a turbulent boundary layer at Reτ=1160 obtained by Ganapathisubramani et al. (2006) were investigated. 3D swirl strength was used to identify vortex cores. The eigenvector of the velocity gradient tensor was used to determine the orientation of each core, and the resulting eigenvector direction was compared with the average vorticity direction. Circulation of the cores was calculated using the vorticity vector only and using the vorticity vector projected onto the eigenvector. The probability distribution of the angle between the eigenvector and the vorticity vector indicated a peak at 15-20 degrees. The eigenvector angle distributions indicate that at z^+=110, more hairpin legs cross the measurement plane while at z/δ = 0.53, more heads are evident. Details of the orientation and circulation distributions will be discussed in the presentation.

  20. A numerical study on helical vortices induced by a short twisted tape in a circular pipe

    Directory of Open Access Journals (Sweden)

    Wen Liu

    2015-03-01

    Full Text Available Helical vortices, as one kind of secondary flows, are recently observed downstream of the short twisted tape. The behaviors of vortices, which have significant effects on the efficiency of twisted tape, are not well understood. As such, the formation and development of helical vortices induced by the short twisted tape are studied numerically. The results show that two symmetrical stable helical vortices are present downstream of the twisted tape. The values of radial velocities cannot be neglected due to the presence of the vortices. The vortices form in the twisted tape and remain the structure downstream of the twisted tape. Torsion promotes the formation of helical vortices. The intensities of helical vortices decay along the streamwise direction. With the increasing Reynolds numbers, the intensities of helical vortices increase, and the trend is in agreement with the swirl intensities. The intensities of helical vortices decay slowly compared with the intensities of swirling flow.

  1. Right ventricular hydatid cyst ruptured to pericardium

    Directory of Open Access Journals (Sweden)

    Feridoun Sabzi

    2015-01-01

    Full Text Available Cardiac hydatidosis is rare presentation of body hydatidosis. Incidence of cardiac involvements range from 5% to 5% of patients with hydatid disease. Most common site of hydatid cyst in heart is interventricular septum and left ventricular free wall. Right ventricular free wall involvement by cyst that ruptured to pericardial cavity is very rare presentation of hydatid cyst. Cardiac involvement may have serious consequences such as rupture to blood steam or pericardial cavity. Both the disease and its surgical treatment carry a high complication rate, including rupture leading to cardiac tamponade, anaphylaxis and also death. In the present report, a 43-year-old man with constrictive pericarditis secondary to a pericardial hydatid cyst is described.

  2. Complex Convective Thermal Fluxes and Vorticity Structure

    Science.gov (United States)

    Redondo, Jose M.; Tellez, Jackson; Sotillos, Laura; Lopez Gonzalez-Nieto, Pilar; Sanchez, Jesus M.; Furmanek, Petr; Diez, Margarita

    2015-04-01

    Local Diffusion and the topological structure of vorticity and velocity fields is measured in the transition from a homogeneous linearly stratified fluid to a cellular or layered structure by means of convective cooling and/or heating[1,2]. Patterns arise by setting up a convective flow generated by an array of Thermoelectric devices (Peltier/Seebeck cells) these are controlled by thermal PID generating a buoyant heat flux [2]. The experiments described here investigate high Prandtl number mixing using brine and fresh water in order to form density interfaces and low Prandtl number mixing with temperature gradients. The set of dimensionless parameters define conditions of numeric and small scale laboratory modeling of environmental flows. Fields of velocity, density and their gradients were computed and visualized [3,4]. When convective heating and cooling takes place the combination of internal waves and buoyant turbulence is much more complicated if the Rayleigh and Reynolds numbers are high in order to study entrainment and mixing. Using ESS and selfsimilarity structures in the velocity and vorticity fieds and intermittency [3,5] that forms in the non-homogeneous flow is related to mixing and stiring. The evolution of the mixing fronts are compared and the topological characteristics of the merging of plumes and jets in different configurations presenting detailed comparison of the evolution of RM and RT, Jets and Plumes in overall mixing. The relation between structure functions, fractal analysis and spectral analysis can be very useful to determine the evolution of scales. Experimental and numerical results on the advance of a mixing or nonmixing front occurring at a density interface due to body forces [6]and gravitational acceleration are analyzed considering the fractal and spectral structure of the fronts like in removable plate experiments for Rayleigh-Taylor flows. The evolution of the turbulent mixing layer and its complex configuration is studied

  3. Fluid mechanics of blood flow in human fetal left ventricles based on patient-specific 4D ultrasound scans.

    Science.gov (United States)

    Lai, Chang Quan; Lim, Guat Ling; Jamil, Muhammad; Mattar, Citra Nurfarah Zaini; Biswas, Arijit; Yap, Choon Hwai

    2016-10-01

    The mechanics of intracardiac blood flow and the epigenetic influence it exerts over the heart function have been the subjects of intense research lately. Fetal intracardiac flows are especially useful for gaining insights into the development of congenital heart diseases, but have not received due attention thus far, most likely because of technical difficulties in collecting sufficient intracardiac flow data in a safe manner. Here, we circumvent such obstacles by employing 4D STIC ultrasound scans to quantify the fetal heart motion in three normal 20-week fetuses, subsequently performing 3D computational fluid dynamics simulations on the left ventricles based on these patient-specific heart movements. Analysis of the simulation results shows that there are significant differences between fetal and adult ventricular blood flows which arise because of dissimilar heart morphology, E/A ratio, diastolic-systolic duration ratio, and heart rate. The formations of ventricular vortex rings were observed for both E- and A-wave in the flow simulations. These vortices had sufficient momentum to last until the end of diastole and were responsible for generating significant wall shear stresses on the myocardial endothelium, as well as helicity in systolic outflow. Based on findings from previous studies, we hypothesized that these vortex-induced flow properties play an important role in sustaining the efficiency of diastolic filling, systolic pumping, and cardiovascular flow in normal fetal hearts.

  4. Left and right ventricular diastolic function in hemodialysis patients.

    Science.gov (United States)

    Rudhani, Ibrahim Destan; Bajraktari, Gani; Kryziu, Emrush; Zylfiu, Bejtush; Sadiku, Shemsedin; Elezi, Ymer; Rexhepaj, Nehat; Vitia, Arber; Emini, Merita; Abazi, Murat; Berbatovci-Ukimeraj, M; Kryeziu, Kaltrina; Hsanagjekaj, Venera; Korca, Hajrije; Ukimeri, Aferdita

    2010-11-01

    The aim of this prospective study was the assessment of left ventricular and right ventricular diastolic function in patients on hemodialysis (HD) and the correlation of this function with the duration of HD. The study included 42 patients (22 females and 20 males) with chronic renal failure (CRF), treated with HD, and 40 healthy subjects (24 females and 16 males) with no history of cardiovascular disease and with normal renal function, who constituted the control group. The groups were matched for age and sex. All study patients and control subjects underwent detailed history taking and physical examination. They also underwent electrocardiogram, echocardiography and biochemical and hematological blood analyses. Significant differences were noted between the two groups in the two-dimensional and M-mode echocardiography findings concerning aortic root dimension, transverse diameter of the left atrium, thickness of the interventricular septum, thickness of the left ventricular posterior wall, left ventricular diastolic diameter, left ventricular systolic diameter, shortening fraction, ejection fraction as well as findings from the pulse Doppler study, including E wave, A wave, E/A ratio, deceleration time of E wave (DT-E), acceleration time of E wave (AT-E), tricuspid E and A waves (E tr and A tr ) and E tr /A tr , ratio. There were significant changes in HD patients without arterial hypertension as well in the control group subjects. Our study suggests that the left ventricular and left atrial dimensions as well as the left ventricular wall thickness are augmented in patients with CRF treated with HD compared with the control group. Additionally, the left and right ventricular diastolic function is also reduced in these patients. These differences were also noted in patients with CRF without arterial hypertension. Left ventricular diastolic dysfunction had no correlation with the duration of HD.

  5. Left ventricular mural thrombus

    Energy Technology Data Exchange (ETDEWEB)

    Nixon, J.V.

    1983-08-01

    The identification of mural thrombus in patients with left ventricular aneurysm and mural thrombus probably warrants consideration of long-term anticoagulation. In patients with acute, large, anterior or anteroapical, transmural myocardial infarctions, serial noninvasive examinations are warranted to define a group of patients at high risk for the development of left ventricular aneurysm and/or mural thrombus. Anticoagulants should be considered in patients in whom mural thrombi develop as a complication of their infarction. Patients with congestive cardiomyopathy should be considered for long-term anticoagulation. These recommendations are all tempered by the realization that the use of anticoagulant therapy is not without its own risks. The decision to anticoagulate must be balanced against each individual patient's suitability for such therapy and the individual likelihood of the development of side effects.

  6. Arrhythmogenic right ventricular dysplasia.

    Science.gov (United States)

    Kinsara, A J; Zaman, L; Gorgels, A

    2001-01-01

    Right ventricular dysplasia (RVD) is a disease entity of unknown cause that is characterised by partial or total replacement of RV-muscle by adipose or fibrous tissue. It is a well-recognized cause of arrhythmia and premature sudden death, but usually underdiagnosed. Several noninvasive and invasive diagnostic modalities have been used, however, all may not be positive in a given case. Drug therapy with class 1c, beta-blocker, and amiodarone in variable combination produce varying success rates in preventing recurrent ventricular tachycardia. Failure of the above measures calls for insertion of implantable cardioverter defibrillator. The attention of emergency physicians is drown to this disease as they are the first medical personnel to be presented with this disease as an emergency. Hence their recognition of RVD will ensure early and proper management.

  7. Arrhythmogenic right ventricular cardiomyopathy.

    Science.gov (United States)

    Soni, Roopali; Oade, Yvette

    2011-08-24

    Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare inherited disease of the heart muscle that causes ventricular tachyarrhythmias and sudden death in young people and athletes. It results in fibrofatty replacement of the right ventricle, and the subepicardial region of the left ventricle. It is the most common cause of sudden cardiac death in young people after hypertrophic heart disease. Diagnosis can be difficult and at present there is no cure for ARVC. Prevention of sudden death is the most important management strategy. Paediatricians need to be aware of the possibility of ARVC in adolescents and young adults presenting with palpitations, fatigue, syncope or cardiac arrest. The authors present two cases of apparently healthy teenage boys who died suddenly and unexpectedly. Postmortem examination of the myocardium was strongly suggestive of ARVC in both cases.

  8. In vitro hemodynamic evaluation of ventricular suction conditions of the EVAHEART ventricular assist pump.

    Science.gov (United States)

    Ferreira, Antonio L; Yu, Yih-Choung; Arnold, Dorian K; Vandenberghe, Stijn; Grashow, Jonathan; Kitano, Tomoya; Borzelleca, David; Antaki, James F

    2012-04-30

    Mismatches between pump output and venous return in a continuous-flow ventricular assist device may elicit episodes of ventricular suction. This research describes a series of in vitro experiments to characterize the operating conditions under which the EVAHEART centrifugal blood pump (Sun Medical Technology Research Corp., Nagano, Japan) can be operated with minimal concern regarding left ventricular (LV) suction. The pump was interposed into a pneumatically driven pulsatile mock circulatory system (MCS) in the ventricular apex to aorta configuration. Under varying conditions of preload, afterload, and systolic pressure, the speed of the pump was increased step-wise until suction was observed. Identification of suction was based on pump inlet pressure. In the case of reduced LV systolic pressure, reduced preload (=10 mmHg), and afterload (=60 mmHg), suction was observed for speeds=2,200 rpm. However, suction did not occur at any speed (up to a maximum speed of 2,400 rpm) when preload was kept within 10-14 mmHg and afterload=80 mmHg. Although in vitro experiments cannot replace in vivo models, the results indicated that ventricular suction can be avoided if sufficient preload and afterload are maintained. Conditions of hypovolemia and/or hypotension may increase the risk of suction at the highest speeds, irrespective of the native ventricular systolic pressure. However, in vitro guidelines are not directly transferrable to the clinical situation; therefore, patient-specific evaluation is recommended, which can be aided by ultrasonography at various points in the course of support.

  9. Characteristics and controllability of vortices in ferromagnetics, ferroelectrics, and multiferroics

    Science.gov (United States)

    Zheng, Yue; Chen, W. J.

    2017-08-01

    Topological defects in condensed matter are attracting e significant attention due to their important role in phase transition and their fascinating characteristics. Among the various types of matter, ferroics which possess a switchable physical characteristic and form domain structure are ideal systems to form topological defects. In particular, a special class of topological defects—vortices—have been found to commonly exist in ferroics. They often manifest themselves as singular regions where domains merge in large systems, or stabilize as novel order states instead of forming domain structures in small enough systems. Understanding the characteristics and controllability of vortices in ferroics can provide us with deeper insight into the phase transition of condensed matter and also exciting opportunities in designing novel functional devices such as nano-memories, sensors, and transducers based on topological defects. In this review, we summarize the recent experimental and theoretical progress in ferroic vortices, with emphasis on those spin/dipole vortices formed in nanoscale ferromagnetics and ferroelectrics, and those structural domain vortices formed in multiferroic hexagonal manganites. We begin with an overview of this field. The fundamental concepts of ferroic vortices, followed by the theoretical simulation and experimental methods to explore ferroic vortices, are then introduced. The various characteristics of vortices (e.g. formation mechanisms, static/dynamic features, and electronic properties) and their controllability (e.g. by size, geometry, external thermal, electrical, magnetic, or mechanical fields) in ferromagnetics, ferroelectrics, and multiferroics are discussed in detail in individual sections. Finally, we conclude this review with an outlook on this rapidly developing field.

  10. Idiopathic Fascicular Ventricular Tachycardia

    Directory of Open Access Journals (Sweden)

    Johnson Francis

    2004-07-01

    Full Text Available Idiopathic fascicular ventricular tachycardia is an important cardiac arrhythmia with specific electrocardiographic features and therapeutic options. It is characterized by relatively narrow QRS complex and right bundle branch block pattern. The QRS axis depends on which fascicle is involved in the re-entry. Left axis deviation is noted with left posterior fascicular tachycardia and right axis deviation with left anterior fascicular tachycardia. A left septal fascicular tachycardia with normal axis has also been described. Fascicular tachycardia is usually seen in individuals without structural heart disease. Response to verapamil is an important feature of fascicular tachycardia. Rare instances of termination with intravenous adenosine have also been noted. A presystolic or diastolic potential preceding the QRS, presumed to originate from the Purkinje fibers can be recorded during sinus rhythm and ventricular tachycardia in many patients with fascicular tachycardia. This potential (P potential has been used as a guide to catheter ablation. Prompt recognition of fascicular tachycardia especially in the emergency department is very important. It is one of the eminently ablatable ventricular tachycardias. Primary ablation has been reported to have a higher success, lesser procedure time and fluoroscopy time

  11. Dynamic, Thermodynamic and Vorticity Budget Analysis of a Simulated Tornado

    Science.gov (United States)

    Yin, Yue

    Data from a very high resolution (30m grid spacing) simulation of a long-lived EF5 tornado embedded in a supercell was used to examine the dynamic and thermodynamic quantities associated with the evolution of the simulated tornado. A Eulerian vertical vorticity budget analysis was performed in a volume bounding the lowest grid layer inside the tornado at various stages to better understand the possible vorticity sources for the low-level tornado, particularly the role of small-scale vortices present primarily along the forward-flank downdraft boundary. The dynamic and thermodynamic fields exhibit similar features to past studies such as slightly positive pressure perturbations along the rear-flank downdraft boundary, small-scale downdrafts with positive potential temperature perturbation to the southwest of the tornado, two-celled structure of the tornado, etc. The rear-flank downdraft in this simulation differs from the classic conceptual model because the vertical velocity was found to be either close to zero or slightly positive in a distinctive region wrapping partially around the major updraft, where previous studies often found a prominent rear-flank downdraft. The vertical vorticity budget analysis shows that the stretching term and the vertical flux term largely oppose each other with nearly the same magnitude throughout the analysis period. The tilting term is almost zero (though slightly positive) throughout the genesis stage, and makes a small and positive contribution in the mature and late mature phases of the tornado. The horizontal flux term makes the greatest contribution in the vertical vorticity source for the tornado during the genesis stage and a significant contribution during the maintenance period. This suggests that the small-scale vortices present along the forward-flank downdraft boundary flowing towards and merging with the tornado are the major vertical vorticity source for the development of the tornado. This, and the lack of a cohesive

  12. CASE REPORT Arrythmogenic right ventricular dysplasia ...

    African Journals Online (AJOL)

    RBBB: right bundle-branch block. RV: right ventricular. RVEDV: right ventricular end diastolic volume. RVEF: right ventricular ejection fraction. RVOT: right ventricular outflow tract. SAECG: signal averaged electrocardiogram. VT: ventricular tachycardia. 'Modifications of the orginal criteria have been proposed to facilitate ...

  13. Vortical structures in pool fires: Observation, speculation, and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Tieszen, S.R.; Nicolette, V.F.; Gritzo, L.A.; Moya, J.L. [Sandia National Labs., Albuquerque, NM (United States); Holen, J.K. [SINTEF/NTH, Trondheim (Norway). Div. Thermodynamics; Murray, D. [Naval Air Warfare Center, China Lake, CA (United States)

    1996-11-01

    While all fires are complex and involve many phenomena, this report is limited to large, turbulent liquid-hydrocarbon pool fires. Large, liquid-hydrocarbon pool fires present a risk in petrochemical storage and processing facilities and transportation systems that contain large amounts of liquid hydrocarbons. This report describes observations, speculations, and numerical simulations of vortical structures in pool fires. Vortical structures are observed in fires with length scales ranging from those that bend millimeter-thick flame zones to those that entrain air many meters from the edge of the fire to its centerline. The authors propose that baroclinic vorticity generation is primarily responsible for production of rotational motion at small scale and that amalgamation is responsible for the production of large-scale rotational structures from the myriad of small-scale structures. Numerical simulations show that vortical structures having time-mean definitions can be resolved with a Reynolds-Average Navier-Stokes (RANS) approach. However, for vortical structures without time-mean definition, RANS is inappropriate, and another technique, such as Large Eddy Simulation (LES), should be employed. 39 refs., 52 figs., 3 tabs.

  14. Pinned vorticity in rotating superfluids, with application to neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Pines, D.; Shaham, J. (Illinois Univ., Urbana (USA). Dept. of Physics); Alpar, M.A.; Anderson, P.W.

    1981-06-01

    The dynamic consequences of the existence of pinned vorticity in a rotating superfluid are studied by means of a simple model: the behavior of a rotating cylinder which contains a uniform region of either weakly or strongly pinned vorticity and which is being spun up or spun down by an external torque. It is shown that in the case of strong pinning, spin down can lead to periodic jumps (glitches) in the rotation frequency of the cylinder, followed by quasi-oscillatory relaxation, while in the case of weak pinning no glitches occur unless the cylinder is shaken so violently that vortices unpin. We conclude that the giant glitches and post-glitch behavior observed in the Vela pulsar may be explained by the sudden release of some 10% of the strongly pinned vortices in the neutron crust every few years as a result of pulsar spin down. We further suggest that the post-glitch behavior observed in the Crab pulsar can be explained if the macroglitches represent vorticity jumps induced by small starquakes in the weakly pinned vortex region expected in the crust of a young neutron star, and that the differences in ''glitch'' behavior of the Crab, Vela, and older pulsars may be explained on evolutionary grounds.

  15. A generalised form of Lait's modified potential vorticity

    Science.gov (United States)

    Mueller, R.; Guenther, G.

    2003-04-01

    Ertel's potential vorticity P is in wide spread use as a diagnostic of dynamical processes in the stratosphere. For a variety of applications however, the exponential increase of P with altitude is problematic. For this reason, Lait, (JAS, 1994) proposed a modified potential vorticity Pi_L, where a physically meaningful scaling is introduced that removes much of the altitude dependence of P. % Here we propose a generalised form of Pi_L by introducing an additional degree of freedom in the scaling. Such a scaling may alternatively be derived by considering a more general form of potential vorticity, where polytropic temperature rather than potential temperature is used as a hydrodynamical invariant. This generalised form of Pi_L possesses the same conservation properties as Pi_L itself and as the classical potential vorticity P , but can be adjusted more closely to the specific situation under investigation. Comparison, over a large altitude range in the stratosphere, of fields of the generalised modified potential vorticity Pi_g with dynamical measures of the polar vortex edge and with observations of the long-lived trace gas N_2O show that Pi_g constitutes a more intuitively interpretable quantity than Pi_L.

  16. Effect of the prosthetic mitral valve on vortex dynamics and turbulence of the left ventricular flow

    Science.gov (United States)

    Querzoli, G.; Fortini, S.; Cenedese, A.

    2010-04-01

    Mechanical heart valves implanted in mitral position have a great effect on the ventricular flow. Changes include alteration of the dynamics of the vortical structures generated during the diastole and the onset of turbulence, possibly affecting the efficiency of the heart pump or causing blood cell damage. Modifications to the hemodynamics in the left ventricle, when the inflow through the mitral orifice is altered, were investigated in vitro using a silicone rubber, flexible ventricle model. Velocity fields were measured in space and time by means of an image analysis technique: feature tracking. Three series of experiments were performed: one with a top hat inflow velocity profile (schematically resembling physiological conditions), and two with mechanical prosthetic valves of different design, mounted in mitral position—one monoleaflet and the other bileaflet. In each series of runs, two different cardiac outputs have been examined by changing the stroke volume. The flow was investigated in terms of phase averaged velocity field and second order moments of turbulent fluctuations. Results show that the modifications in the transmitral flow change deeply the interaction between the coherent structures generated during the first phase of the diastole and the incoming jet during the second diastolic phase. Top hat inflow gives the coherent structures which are optimal, among the compared cases, for the systolic function. The flow generated by the bileaflet valve preserves most of the beneficial features of the top hat inflow, whereas the monoleaflet valve generates a strong jet which discourages the permanence of large coherent structures at the end of the diastole. Moreover, the average shear rate magnitudes induced by the smoother flow pattern of the case of top hat inflow are nearly halved in comparison with the values measured with the mechanical valves. Finally, analysis of the turbulence statistics shows that the monoleaflet valves yield higher turbulence

  17. Prevalence and correlates of ventricular premature beats detected by ambulatory electrocardiography in working populations.

    Science.gov (United States)

    Green, M S; Jucha, E; Luz, J; Cocos, M; Nurynberg, M; Rosenberg, N

    1988-05-01

    The associations of ventricular premature beats detected on a one-hour ambulatory electrocardiogram with demographic, behavioral, physiologic, and anthropometric variables were examined in 2,331 factory workers aged 20-69 years. Ventricular premature beats were more prevalent with increasing age and with abnormal resting electrocardiograms. From the age of 40, they were more common among males than among females. An association with ethnicity was observed, ventricular premature beats being most common among Israelis of European origin. In univariate analysis, resting heart rate was inversely associated with the presence of ventricular premature beats for females only. Ambulatory heart rate was positively associated with ventricular premature beats only among males. No associations with smoking habits or relative weight were found. Among males and females with normal electrocardiograms, systolic and diastolic blood pressures were significant correlates of ventricular premature beats in univariate analysis and after controlling for age, resting and ambulatory heart rates, and ethnic origin.

  18. Determinants of left ventricular mass in obesity; a cardiovascular magnetic resonance study

    Directory of Open Access Journals (Sweden)

    Clarke Kieran

    2009-04-01

    Full Text Available Abstract Background Obesity is linked to increased left ventricular mass, an independent predictor of mortality. As a result of this, understanding the determinants of left ventricular mass in the setting of obesity has both therapeutic and prognostic implications. Using cardiovascular magnetic resonance our goal was to elucidate the main predictors of left ventricular mass in severely obese subjects free of additional cardiovascular risk factors. Methods 38 obese (BMI 37.8 ± 6.9 kg/m2 and 16 normal weight controls subjects, (BMI 21.7 ± 1.8 kg/m2, all without cardiovascular risk factors, underwent cardiovascular magnetic resonance imaging to assess left ventricular mass, left ventricular volumes and visceral fat mass. Left ventricular mass was then compared to serum and anthropometric markers of obesity linked to left ventricular mass, i.e. height, age, blood pressure, total fat mass, visceral fat mass, lean mass, serum leptin and fasting insulin level. Results As expected, obesity was associated with significantly increased left ventricular mass (126 ± 27 vs 90 ± 20 g; p 2 = 0.77. Conclusion The left ventricular hypertrophic response to obesity in the absence of additional cardiovascular risk factors is mainly attributable to increases in lean body mass, LV stroke volume and visceral fat mass. In view of the well documented link between obesity, left ventricular hypertrophy and mortality, these findings have potentially important prognostic and therapeutic implications for primary and secondary prevention.

  19. Electronic circuit detects left ventricular ejection events in cardiovascular system

    Science.gov (United States)

    Gebben, V. D.; Webb, J. A., Jr.

    1972-01-01

    Electronic circuit processes arterial blood pressure waveform to produce discrete signals that coincide with beginning and end of left ventricular ejection. Output signals provide timing signals for computers that monitor cardiovascular systems. Circuit operates reliably for heart rates between 50 and 200 beats per minute.

  20. On Chirality of the Vorticity of the Universe

    Directory of Open Access Journals (Sweden)

    Davor Palle

    2012-05-01

    Full Text Available The presence of dark energy in the Universe challenges the Einstein’s theory of gravity at cosmic scales. It motivates the inclusion of rotational degrees of freedom in the Einstein–Cartan gravity, representing the minimal and the most natural extension of the General Relativity. One can, consequently, expect the violation of the cosmic isotropy by the rotating Universe. We study chirality of the vorticity of the Universe within the Einstein–Cartan cosmology. The role of the spin of fermion species during the evolution of the Universe is studied by averaged spin densities and Einstein–Cartan equations. It is shown that spin density of the light Majorana neutrinos acts as a seed for vorticity at early stages of the evolution of the Universe. Its chirality can be evaluated in the vicinity of the spacelike infinity. It turns out that vorticity of the Universe has right-handed chirality.

  1. Pair interactions of heavy vortices in quantum fluids

    Science.gov (United States)

    Pshenichnyuk, Ivan A.

    2018-02-01

    The dynamics of quantum vortex pairs carrying heavy doping matter trapped inside their cores is studied. The nonlinear classical matter field formalism is used to build a universal mathematical model of a heavy vortex applicable to different types of quantum mixtures. It is shown how the usual vortex dynamics typical for undoped pairs qualitatively changes when heavy dopants are used: heavy vortices with opposite topological charges (chiralities) attract each other, while vortices with the same charge are repelled. The force responsible for such behavior appears as a result of superposition of vortices velocity fields in the presence of doping substance and can be considered as a special realization of the Magnus effect. The force is evaluated quantitatively and its inverse proportionality to the distance is demonstrated. The mechanism described in this paper gives an example of how a light nonlinear classical field may realize repulsive and attractive interactions between embedded heavy impurities.

  2. Multicharged optical vortices induced in a dissipative atomic vapor system

    CERN Document Server

    Zhang, Yiqi; Wu, Zhenkun; Yuan, Chenzhi; Wang, Ruimin; Lu, Keqing; Zhang, Yanpeng

    2013-01-01

    We investigate numerically the dynamics of optical vortex beams carrying different topological charges, launched in a dissipative three level ladder type nonlinear atomic vapor. We impose the electromagnetically induced transparency (EIT) condition on the medium. Linear, cubic, and quintic susceptibilities, considered simultaneously with the dressing effect, are included in the analysis. Generally, the beams slowly expand during propagation and new vortices are induced, commonly appearing in oppositely charged pairs. We demonstrate that not only the form and the topological charge of the incident beam, but also its growing size in the medium greatly affect the formation and evolution of vortices. We formulate common rules for finding the number of induced vortices and the corresponding rotation directions, stemming from the initial conditions of various incident beams, as well as from the dynamical aspects of their propagation. The net topological charge of the vortex is conserved during propagation, as it sh...

  3. Inelastic scattering of xenon atoms by quantized vortices in superfluids

    CERN Document Server

    Pshenichnyuk, I A

    2016-01-01

    We study inelastic interactions of particles with quantized vortices in superfluids by using a semi-classical matter wave theory that is analogous to the Landau two-fluid equations, but allows for the vortex dynamics. The research is motivated by recent experiments on xenon doped helium nanodroplets that show clustering of the impurities along the vortex cores. We numerically simulate the dynamics of trapping and interactions of xenon atoms by quantized vortices in superfluid helium and the obtained results can be extended to scattering of other impurities by quantized vortices. Different energies and impact parameters of incident particles are considered. We show that inelastic scattering is closely linked to the generation of Kelvin waves along a quantized vortex during the interaction even if there is no capture. The capture criterion of an impurity is formulated in terms of the binding energy.

  4. Vorticity scaling and intermittency in drift-interchange plasma turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Dura, P. D.; Hnat, B.; Robinson, J.; Dendy, R. O. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2012-09-15

    The effects of spatially varying magnetic field strength on the scaling properties of plasma turbulence, modelled by an extended form of Hasegawa-Wakatani model, are investigated. We study changes in the intermittency of the velocity, density, and vorticity fields, as functions of the magnetic field inhomogeneity C=-{partial_derivative} ln B/{partial_derivative}x. While the velocity fluctuations are always self-similar and their scaling is unaffected by the value of C, the intermittency levels in density and vorticity change with parameter C, reflecting morphological changes in the coherent structures due to the interchange mechanism. Given the centrality of vorticity in conditioning plasma transport, this result is of interest in scaling the results of transport measurements and simulations in tokamak edge plasmas, where drift-interchange turbulence in the presence of a magnetic field gradient is likely to occur.

  5. Vorticity scaling and intermittency in drift-interchange plasma turbulence

    Science.gov (United States)

    Dura, P. D.; Hnat, B.; Robinson, J.; Dendy, R. O.

    2012-09-01

    The effects of spatially varying magnetic field strength on the scaling properties of plasma turbulence, modelled by an extended form of Hasegawa-Wakatani model, are investigated. We study changes in the intermittency of the velocity, density, and vorticity fields, as functions of the magnetic field inhomogeneity C =-∂ ln B/∂x. While the velocity fluctuations are always self-similar and their scaling is unaffected by the value of C, the intermittency levels in density and vorticity change with parameter C, reflecting morphological changes in the coherent structures due to the interchange mechanism. Given the centrality of vorticity in conditioning plasma transport, this result is of interest in scaling the results of transport measurements and simulations in tokamak edge plasmas, where drift-interchange turbulence in the presence of a magnetic field gradient is likely to occur.

  6. The Evaluation of the Boundary Vorticity by URANS and LES Methods

    Directory of Open Access Journals (Sweden)

    Ion MALAEL

    2015-12-01

    Full Text Available The role of concentrated vorticity in fluid dynamics phenomena, concerning both the vorticity creation at the boundary and the response to the flow field is not wholly understood. The Lighthill describes the vorticity production at a solid boundary as a slow diffusion of the vorticity similar to the Fourier heat conduction. In the paper it is shown that this mechanism associated to URANS method is not applied to the concentrated vorticity case, and the LES method better reproduces the flows involving concentrations vorticity.

  7. Nonlinear Dynamics of Vortices in Different Types of Grain Boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Sheikhzada, Ahmad [Old Dominion Univ., Norfolk, VA (United States)

    2017-05-01

    As a major component of linear particle accelerators, superconducting radio-frequency (SRF) resonator cavities are required to operate with lowest energy dissipation and highest accelerating gradient. SRF cavities are made of polycrystalline materials in which grain boundaries can limit maximum RF currents and produce additional power dissipation sources due to local penetration of Josephson vortices. The essential physics of vortex penetration and mechanisms of dissipation of vortices driven by strong RF currents along networks of grain boundaries and their contribution to the residual surface resistance have not been well understood. To evaluate how GBs can limit the performance of SRF materials, particularly Nb and Nb3Sn, we performed extensive numerical simulations of nonlinear dynamics of Josephson vortices in grain boundaries under strong dc and RF fields. The RF power due to penetration of vortices both in weakly-coupled and strongly-coupled grain boundaries was calculated as functions of the RF field and frequency. The result of this calculation manifested a quadratic dependence of power to field amplitude at strong RF currents, an illustration of resistive behavior of grain boundaries. Our calculations also showed that the surface resistance is a complicated function of field controlled by penetration and annihilation of vortices and antivortices in strong RF fields which ultimately saturates to normal resistivity of grain boundary. We found that Cherenkov radiation of rapidly moving vortices in grain boundaries can produce a new instability causing generation of expanding vortex-antivortex pair which ultimately drives the entire GB in a resistive state. This effect is more pronounced in polycrystalline thin film and multilayer coating structures in which it can cause significant increase in power dissipation and results in hysteresis effects in I-V characteristics, particularly at low temperatures.

  8. Relation of maximum blood pressure during exercise and regular physical activity in normotensive men with left ventricular mass and hypertrophy. MARATHOM Investigators. Medida de la Actividad fisica y su Relación Ambiental con Todos los Lípidos en el HOMbre.

    Science.gov (United States)

    Molina, L; Elosua, R; Marrugat, J; Pons, S

    1999-10-15

    The relation between maximum systolic blood pressure (BP) during exercise and left ventricular (LV) mass is controversial. Physical activity also induces LV mass increase. The objective was to assess the relation between BP response to exercise and LV mass in normotensive men, taking into account physical activity practice. A cross-sectional study was performed. Three hundred eighteen healthy normotensive men, aged between 20 and 60 years, participated in this study. The Minnesota questionnaire was used to assess physical activity practice. An echocardiogram and a maximum exercise test were performed. LV mass was calculated and indexed to body surface area. LV hypertrophy was defined as a ventricular mass index > or =134 g/m2. BP was measured at the moment of maximum effort. Hypertensive response was considered when BP was > or =210 mm Hg. In the multiple linear regression model, maximum systolic BP was associated with LV mass index and correlation coefficient was 0.27 (SE 0.07). Physical activity practice and age were also associated with LV mass. An association between hypertensive response to exercise and LV hypertrophy was observed (odds ratio 3.16). Thus, BP response to exercise is associated with LV mass and men with systolic BP response > or =210 mm Hg present a 3-times higher risk of LV hypertrophy than those not reaching this limit. Physical activity practice is related to LV mass, but not to LV hypertrophy.

  9. Right ventricular function during acute exacerbation of severe equine asthma.

    Science.gov (United States)

    Decloedt, A; Borowicz, H; Slowikowska, M; Chiers, K; van Loon, G; Niedzwiedz, A

    2017-09-01

    Pulmonary hypertension has been described in horses with severe equine asthma, but its effect on the right ventricle has not been fully elucidated. To evaluate right ventricular structure and function after a 1-week period of pulmonary hypertension secondary to acute exacerbation of severe equine asthma. Prospective study. A clinical episode of severe equine asthma was induced experimentally in six susceptible horses. Examinations in remission and on day 7 of the clinical episode included a physical examination with clinical scoring, echocardiography, arterial blood gas measurements, venous blood sampling for cardiac biomarkers, intracardiac pressure measurements, right ventricular and right atrial myocardial biopsies, airway endoscopy and bronchoalveolar lavage. After 1 month of recovery, physical examination, echocardiography and cardiac biomarker analysis were repeated. Echocardiographic and pressure measurements were compared with those in 10 healthy control horses. All horses developed clinical signs of acute pulmonary obstruction. Right heart pressures increased significantly. Altered right ventricular function could be detected by tissue Doppler and speckle tracking echocardiography. Cardiac troponin concentrations did not increase significantly, but were highly elevated in one horse which exercised in the paddock prior to sampling. Focal neutrophil infiltration was present in two myocardial samples. Even in remission, asthmatic horses showed a thicker right ventricular wall, an increased left ventricular end-systolic eccentricity index at chordal level and decreased right ventricular longitudinal strain compared with controls. The induced clinical episode was rather mild and the number of horses was limited because of the invasive nature of the study. Pulmonary obstruction in asthmatic horses induces pulmonary hypertension with right ventricular structural and functional changes. © 2017 EVJ Ltd.

  10. Manipulation of pancake vortices by rotating a Josephson vortex lattice

    Energy Technology Data Exchange (ETDEWEB)

    Crisan, A [Department of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Bending, S J [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Tamegai, T [Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8627 (Japan)

    2008-01-15

    Scanning Hall probe microscopy has been used to demonstrate the manipulation of pancake vortices by rotating the Josephson vortex lattice in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} single crystals in the interacting crossing lattices regime. Creation of one-dimensional pancake vortex chains trapped on Josephson vortices, and the subsequent rotation of the chains were realized by independently controlling magnetic fields in three orthogonal directions. The anisotropy parameter determined from the in-plane distances between vortex chains in various in-plane fields is consistent with commonly accepted values.

  11. (Non)-renormalization of the chiral vortical effect coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Golkar, Siavash; Son, Dam T. [Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago,5640 South Ellis Ave., Chicago, IL 60637 (United States)

    2015-02-26

    We show using diagramtic arguments that in some (but not all) cases, the temperature dependent part of the chiral vortical effect coefficient is independent of the coupling constant. An interpretation of this result in terms of quantization in the effective 3 dimensional Chern-Simons theory is also given. In the language of 3D, dimensionally reduced theory, the value of the chiral vortical coefficient is related to the formula ∑{sub n=1}{sup ∞}n=−1/12. We also show that in the presence of dynamical gauge fields, the CVE coefficient is not protected from renormalization, even in the large N limit.

  12. Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices

    KAUST Repository

    Akosa, Collins Ashu

    2017-03-01

    We propose that topological spin currents flowing in topologically nontrivial magnetic textures, such as magnetic skyrmions and vortices, produce an intrinsic nonadiabatic torque of the form Tt∼[(∂xm×∂ym)·m]∂ym. We show that this torque, which is absent in one-dimensional domain walls and/or nontopological textures, is responsible for the enhanced nonadiabaticity parameter observed in magnetic vortices compared to one-dimensional textures. The impact of this torque on the motion of magnetic skyrmions is expected to be crucial, especially to determine their robustness against defects and pinning centers.

  13. Strain and vorticity patterns in ideally ductile transpression zones

    Science.gov (United States)

    Robin, Pierre-Yves F.; Cruden, Alexander R.

    1994-04-01

    The prevalent model for ductile shear zones assumes that they develop by progressive simple shearing, resulting in a monoclinic fabric in which the vorticity vector is parallel to the shear zone and perpendicular to the lineation. But some ductile shear zones exhibit an amount of coaxial flattening, or a fabric pattern which appear to be incompatible with the assumptions of plane strain and progressive simple shear. In certain sections of the Archean Larder Lake—Cadillac deformation zone (LCDZ), for example, vorticity indicators (asymmetric pressure wings, Z-folds, SC fabrics), best seen on horizontal surfaces, indicate dextral transcurrent motion, whereas stretching lineations have variable but steep plunges. In the Proterozoic Mylonite Zone (MZ) of south-west Sweden, vorticity indicators combined with foliation and lineation data suggest a continuous change from reverse dip-slip motion close to the footwall to sinistral transcurrent motion adjacent to the hangingwall of the zone. Such departures from the ideal progressive simple shear zone pattern may in fact be common. Rather than invoke two stages of deformation, we explore the possibility that these patterns could be the result of ductile transpression. Ductile transpression between relatively rigid walls implies an extrusion of material out of the shear zone. When the material cannot slip freely along the boundaries of the zone, the extrusion strain is by necessity heterogeneous. In order to explore these heterogeneous strain distributions, we have developed a continuum mechanics model in which the 'transpressed' rock is a linear viscous material squeezed upward between two parallel, rigid, vertical walls. Transpression is further generalized by modelling oblique (i.e. with a dip-slip component) relative displacements of the walls. Models, which can vary in their obliquity and their 'press'/'trans' ratio, are examined for their distributions of K-values, strain rate intensity, 'lineation' (direction of

  14. Unfolding of vortices into topological stripes in a multiferroic material.

    Science.gov (United States)

    Wang, X; Mostovoy, M; Han, M G; Horibe, Y; Aoki, T; Zhu, Y; Cheong, S-W

    2014-06-20

    Multiferroic hexagonal RMnO(3) (R=rare earths) crystals exhibit dense networks of vortex lines at which six domain walls merge. While the domain walls can be readily moved with an applied electric field, the vortex cores so far have been impossible to control. Our experiments demonstrate that shear strain induces a Magnus-type force pulling vortices and antivortices in opposite directions and unfolding them into a topological stripe domain state. We discuss the analogy between this effect and the current-driven dynamics of vortices in superconductors and superfluids.

  15. On the interaction between two oppositely signed, shielded, monopolar vortices

    DEFF Research Database (Denmark)

    Schmidt, M.R.; Beckers, M.; Nielsen, A.H.

    1998-01-01

    solutions of the two-dimensional Navier-Stokes equations. A comparative study between the laboratory experiments and numerical simulations is performed. The vorticity distribution measured in the early stage of the evolution in the laboratory is used as initial data for the simulations, and an additional...... damping term in the Navier-Stokes equations, that accounts for the vertical diffusion in the laboratory experiments, is used. The results show that, depending on the initial separation between the vortices, the shields of the monopoles are peeled off and indeed a compact dipole with a linear (omega...

  16. Vorticity Measurement using LG Laser Beams with Orbital Angular Momentum

    Science.gov (United States)

    Kooochesfahani, Manoochehr; Pouya, Shahram; Safaripour, Alireza; Ryabtsev, Anton; Dantus, Marcos

    2016-11-01

    We present direct measurement of vorticity in a fluid flow based on angular velocity measurement of microparticles contained in the fluid. The method uses Laguerre-Gaussian (LG) laser beams that possess orbital angular momentum (OAM), a spatial (azimuthal) modulation of the beam phase front, and takes advantage of the rotational Doppler shift from microparticles intersecting the beam focus. Results are shown for the flow field of solid body rotation, where the flow vorticity is known precisely. This work was supported by AFOSR Award Number FA9550-14-1-0312.

  17. Right ventricular metastasis of leiomyosarcoma

    Directory of Open Access Journals (Sweden)

    Stagmo Martin

    2009-05-01

    Full Text Available Abstract Metastatic presentation of leiomyosarcoma in the heart is very rare. We present transthoracic echocardiography and combined PET/CT images of a case with a large right ventricular metastasis of leiomyosarcoma. The patient was placed on cytostatic drugs for palliative purposes, but passed away one month later because of an untreatable ventricular tackycardia.

  18. Idiopathic Fascicular Left Ventricular Tachycardia.

    Science.gov (United States)

    Alahmad, Yaser; Asaad, Nidal Ahmad; Arafa, Salaheddin Omran; Ahmad Khan, Shahul Hameed; Mahmoud, Alsayed

    2017-01-01

    Idiopathic left fascicular ventricular tachycardia (ILFVT) is characterized by right bundle branch block morphology and left axis deviation. We report a case of idiopathic left ventricular fascicular tachycardia in a young 31-year-old male patient presenting with a narrow complex tachycardia.

  19. Idiopathic Fascicular Left Ventricular Tachycardia

    OpenAIRE

    Alahmad, Yaser; Asaad, Nidal Ahmad; Arafa, Salaheddin Omran; Ahmad Khan, Shahul Hameed; Mahmoud, Alsayed

    2017-01-01

    Idiopathic left fascicular ventricular tachycardia (ILFVT) is characterized by right bundle branch block morphology and left axis deviation. We report a case of idiopathic left ventricular fascicular tachycardia in a young 31-year-old male patient presenting with a narrow complex tachycardia.

  20. Cerebrovascular accidents in patients with a ventricular assist device.

    Science.gov (United States)

    Tsukui, Hiroyuki; Abla, Adib; Teuteberg, Jeffrey J; McNamara, Dennis M; Mathier, Michael A; Cadaret, Linda M; Kormos, Robert L

    2007-07-01

    A cerebrovascular accident is a devastating adverse event in a patient with a ventricular assist device. The goal was to clarify the risk factors for cerebrovascular accident. Prospectively collected data, including medical history, ventricular assist device type, white blood cell count, thrombelastogram, and infection, were reviewed retrospectively in 124 patients. Thirty-one patients (25%) had 48 cerebrovascular accidents. The mean ventricular assist device support period was 228 and 89 days in patients with and without cerebrovascular accidents, respectively (P cerebrovascular accidents occurred within 4 months after implantation. Actuarial freedom from cerebrovascular accident at 6 months was 75%, 64%, 63%, and 33% with the HeartMate device (Thoratec Corp, Pleasanton, Calif), Thoratec biventricular ventricular assist device (Thoratec Corp), Thoratec left ventricular assist device (Thoratec), and Novacor device (WorldHeart, Oakland, Calif), respectively. Twenty cerebrovascular accidents (42%) occurred in patients with infections. The mean white blood cell count at the cerebrovascular accident was greater than the normal range in patients with infection (12,900/mm3) and without infection (9500/mm3). The mean maximum amplitude of the thrombelastogram in the presence of infection (63.6 mm) was higher than that in the absence of infection (60.7 mm) (P = .0309). The risk of cerebrovascular accident increases with a longer ventricular assist device support period. Infection may activate platelet function and predispose the patient to a cerebrovascular accident. An elevation of the white blood cell count may also exacerbate the risk of cerebrovascular accident even in patients without infection. Selection of device type, prevention of infection, and meticulous control of anticoagulation are key to preventing cerebrovascular accident.

  1. Crystallized and amorphous vortices in rotating atomic-molecular Bose-Einstein condensates

    Science.gov (United States)

    Liu, Chao-Fei; Fan, Heng; Gou, Shih-Chuan; Liu, Wu-Ming

    2014-02-01

    Vortex is a topological defect with a quantized winding number of the phase in superfluids and superconductors. Here, we investigate the crystallized (triangular, square, honeycomb) and amorphous vortices in rotating atomic-molecular Bose-Einstein condensates (BECs) by using the damped projected Gross-Pitaevskii equation. The amorphous vortices are the result of the considerable deviation induced by the interaction of atomic-molecular vortices. By changing the atom-molecule interaction from attractive to repulsive, the configuration of vortices can change from an overlapped atomic-molecular vortices to carbon-dioxide-type ones, then to atomic vortices with interstitial molecular vortices, and finally into independent separated ones. The Raman detuning can tune the ratio of the atomic vortex to the molecular vortex. We provide a phase diagram of vortices in rotating atomic-molecular BECs as a function of Raman detuning and the strength of atom-molecule interaction.

  2. A (dis)continuous finite element model for generalized 2D vorticity dynamics

    NARCIS (Netherlands)

    Bernsen, E.; Bokhove, Onno; van der Vegt, Jacobus J.W.; Wesseling, P.; Onate, E; Periaux, J.

    2006-01-01

    A mixed continuous and discontinuous Galerkin finite element discretization has been constructed for a generalized vorticity-streamfunction formulation in two spatial dimensions. This formulation consists of a hyperbolic (potential) vorticity equation and a linear elliptic equation for a (transport)

  3. Turbulence measurements in an axial rotary blood pump with laser Doppler velocimetry.

    Science.gov (United States)

    Schüle, Chan Y; Affeld, Klaus; Kossatz, Max; Paschereit, Christian O; Kertzscher, Ulrich

    2017-04-18

    The implantation of rotary blood pumps as ventricular assist devices (VADs) has become a viable therapy for quite a number of patients with end-stage heart failure. However, these rotary blood pumps cause adverse events that are related to blood trauma. It is currently believed that turbulence in the pump flow plays a significant role. But turbulence has not been measured to date because there is no optical access to the flow space in rotary blood pumps because of their opaque casings. This difficulty is overcome with a scaled-up model of the HeartMate II (HM II) rotary blood pump with a transparent acrylic housing. A 2-component laser Doppler velocimetry (LDV) system was used for the measurement of time resolved velocity profiles and velocity spectra upstream and downstream of the rotor blades. Observing similarity laws, the speed and pump head were adjusted to correspond closely to the design point of the original pump - 10,600 rpm speed and 80 mmHg pressure head. A model fluid consisting of a water-glycerol mixture was used. The measured velocity spectra were scalable by the Kolmogorov length and the Kolmogorov length was estimated to be between 14 and 24 µm at original scale, thus being about 1.5 to 3 times the size of a red blood cell. It can be concluded that turbulence is indeed present in the investigated blood pump and that it can be described by Kolmogorov's theory of turbulence. The size of the smallest vortices compares well to the turbulence length scales as found in prosthetic heart valves, for example.

  4. The vorticity and angular momentum budgets of Asian summer ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 113; Issue 3. The vorticity and angular momentum ... The flux convergence of omega and relative momenta over the monsoon domain is effectively balanced by pressure torque during the evolution and established phases. Nevertheless, the balance is stronger ...

  5. Tip vorticity reduction and optimization of lifting surfaces

    NARCIS (Netherlands)

    Sparenberg, JA

    In linearized optimization theory, lifting surfaces, moving in an inviscid and incompressible fluid, shed tip vorticity of which the strength has infinite square-root singularities. Here we discuss that an optimization procedure can be coupled to constraints so that the strength of the shed

  6. Compressible dynamic stall vorticity flux control using a dynamic ...

    Indian Academy of Sciences (India)

    be thought of as arising from the rapidly changing strong pressure gradient near the leading edge due to its unsteady motion. Thus, even though the vorticity is produced by the unsteady surface motion, it appears that its subsequent convection through the boundary layer over the airfoil upper surface can only be managed ...

  7. Instability of helical tip vortices in rotor wakes

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær

    2011-01-01

    The conditions for the appearance of instabilities in systems of helical vortices constitute an intriguing problem that still remains partly unsolved. The experimental study of Felli, Camussi & Di Felice (J. Fluid Mech., this issue, vol. 682, 2011, pp. 5-53) has shed new light on some of the basi...

  8. Clustering of heavy particles in vortical flows: a selective review

    Indian Academy of Sciences (India)

    S Ravichandran

    Vortical flows; inertial particles; preferential clustering; sling caustics; particle collisions; warm rain initiation. ... The equation of motion for a small sphere in fluid flow was ... to a Magnus force. The terms with a factor a2Du are called. Faxen corrections, and account for changes in the flow over length scales of the particle size.

  9. Vortices in Bose–Einstein condensates: A review of the ...

    Indian Academy of Sciences (India)

    mode instability; but this is not the only mechanism; (b) the vortex lattice is perfectly triangular right up to the ... themselves in a lattice; this time appears to be independent of temperature; (d) the decay of vortices appears to ..... a state |1〉 to a state |2〉 at a Rabi frequency Ω by using electromagnetic radiation detuned by δ.

  10. The vorticity and angular momentum budgets of Asian summer ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    1School of Geography and Geology, McMaster University, Hamilton, ON, Canada L8S 4K1. 2Centre for Atmospheric Sciences, Indian Institute of Technology-Delhi Hauz Khas, New Delhi 110 016, India. The study delineates the vorticity and angular momentum balances of Asian summer monsoon dur- ing the evolution and ...

  11. Generation of tripolar vortical structures on the beta plane

    DEFF Research Database (Denmark)

    Hesthaven, J.S.; Lynov, Jens-Peter; Juul Rasmussen, J.

    1993-01-01

    A new feature of the long-time evolution of a strong vortex with initially monotonic potential vorticity is found by direct numerical solution of the quasigeostrophic equivalent barotropic equation. Two satellites, which emerge after splitting of an annulus, appear at the vortex periphery. Rotation...

  12. Ionospheric travelling convection vortices observed by the Greenland magnetometer chain

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Stolle, Claudia; Friis-Christensen, Eigil

    2013-01-01

    The Greenland magnetometer array continuously provides geomagnetic variometer data since the early eighties. With the polar cusp passing over it almost every day, the array is suitable to detect ionospheric traveling convection vortices (TCVs), which were rst detected by Friis-Christensen et al...

  13. Vortices in Bose–Einstein condensates: A review of the ...

    Indian Academy of Sciences (India)

    Such vortices have been generated in BEC of alkali atoms by different techniques such as (a) wave function engineering of a two-component BEC, (b) decay of solitons, (c) rotation of a thermal cloud before cooling it below the ... Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India ...

  14. Comparing the dynamics of skyrmions and superconducting vortices

    Energy Technology Data Exchange (ETDEWEB)

    Olson Reichhardt, C.J., E-mail: cjrx@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lin, S.Z. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Ray, D. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Reichhardt, C. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2014-08-15

    Highlights: • We describe similarities and differences between skyrmion and vortex dynamics. • The Magnus force can dramatically alter skyrmion transport. • The pinning becomes very weak when the Magnus force is strong. - Abstract: Vortices in type-II superconductors have attracted enormous attention as ideal systems in which to study nonequilibrium collective phenomena, since the self-ordering of the vortices competes with quenched disorder and thermal effects. Dynamic effects found in vortex systems include depinning, nonequilibrium phase transitions, creep, structural order–disorder transitions, and melting. Understanding vortex dynamics is also important for applications of superconductors which require the vortices either to remain pinned or to move in a controlled fashion. Recently, topological defects called skyrmions have been realized experimentally in chiral magnets. Here we highlight similarities and differences between skyrmion dynamics and vortex dynamics. Many of the previous ideas and experimental setups that have been applied to superconducting vortices can also be used to study skyrmions. We also discuss some of the differences between the two systems, such as the potentially large contribution of the Magnus force in the skyrmion system that can dramatically alter the dynamics and transport properties.

  15. Streaming vorticity flux from oscillating walls with finite amplitude

    Science.gov (United States)

    Wu, J. Z.; Wu, X. H.; Wu, J. M.

    1993-01-01

    How to describe vorticity creation from a moving wall is a long standing problem. This paper discusses relevant issues at the fundamental level. First, it is shown that the concept of 'vorticity flux due to wall acceleration' can be best understood by following fluid particles on the wall rather than observing the flow at fixed spatial points. This is of crucial importance when the time-averaged flux is to be considered. The averaged flux has to be estimated in a wall-fixed frame of reference (in which there is no flux due to wall acceleration at all); or, if an inertial frame of reference is used, the generalized Lagrangian mean (GLM) also gives the same result. Then, for some simple but typical configurations, the time-averaged vorticity flux from a harmonically oscillating wall with finite amplitude is analyzed, without appealing to small perturbation. The main conclusion is that the wall oscillation will produce an additional mean vorticity flux (a fully nonlinear streaming effect), which is partially responsible for the mechanism of vortex flow control by waves. The results provide qualitative explanation for some experimentally and/or computationally observed phenomena.

  16. The decay of wake vortices in the convective boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Holzaepfel, F.; Gerz, T.; Frech, M.; Doernbrack, A.

    2000-03-01

    The decay of three wake vortex pairs of B-747 aircraft in a convectively driven atmospheric boundary layer is investigated by means of large-eddy simulations (LES). This situation is considered as being hazardous as the updraft velocities of a thermal may compensate the induced descent speed of the vortex pair resulting in vortices stalled in the flight path. The LES results, however, illustrate that (i) the primary rectilinear vortices are rapidly deformed on the scale of the alternating updraft and downdraft regions; (ii) parts of the vortices stay on flight level but are quickly eroded by the enhanced turbulence of an updraft; (iii) longest living sections of the vortices are found in regions of relatively calm downdraft flow which augments their descent. Strip theory calculations are used to illustrate the temporal and spatial development of lift and rolling moments experienced by a following medium weight class B-737 aircraft. Characteristics of the respective distributions are analysed. Initially, the maximum rolling moments slightly exceed the available roll control of the B-737. After 60 seconds the probability of rolling moments exceeding 50% of the roll control, a value which is considered as a threshold for acceptable rolling moments, has decreased to 1% of its initial probability. (orig.)

  17. Glitches and pinned vorticity in the Crab pulsar

    Energy Technology Data Exchange (ETDEWEB)

    Alpar, M.A. (Bogazici Univ., Istanbul, Turkey); Anderson, P.W.; Pines, D.; Shaham, J.

    1981-09-01

    It is suggested that the glitch behavior observed in the Crab pulsar is associated with vorticity jumps induced by a starquake or a comparable external fluctuation in the weakly pinned vortex region expected in the crust of a young neutron star, and that the differences in the glitch behavior of the Crab, Vela, and older pulsars may be explained on evolutionary grounds.

  18. Numerical and Experimental Study of Electromagnetically Driven Vortical Flows

    NARCIS (Netherlands)

    Kenjeres, S.; Verdoold, J.; Tummers, M.J.; Hanjalic, K.; Kleijn, C.R.

    2009-01-01

    The paper reports on numerical and experimental investigations of electromagnetically driven vortical flows of an electrically conductive fluid in a generic setup. Two different configurations of permanent magnets are considered: a 3-magnet configuration in which the resulting Lorentz force is

  19. Turbulent transports by secondary flow vortices in a rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Vonka, V.

    1988-02-01

    Experimental data on secondary flow vortices in a rod bundle with pitch-to-diameter ratio P/D=1.3 show weak vortices with the average velocity magnitude only about 0.1% of the mean bulk velocity. The question then arises, how important these weak vortices could still be as a transport mechanism in turbulent flows. The transport of axial momentum by these vortices is analysed quantitatively. While a minor importance is observed for the transport in radial direction, it is found that about half of the total transport in circumferential direction is due to the secondary flow vortex convection. Based on the analogy between the transport of momentum and heat, it is expected in nonisothermal situations that, in radial direction, the contribution can improve the heat transfer coefficient and contribute to better economy of heat transfer installations. In circumferential direction, the contribution helps to smooth out circumferential temperature differences, improves the heat removal from heated surfaces and, through a decrease of the maximum surface temperature, it contributes to passive safety of heat transfer installations.

  20. Directed motion of vortices in faceted Nb films

    CERN Document Server

    Soroka, A K

    2002-01-01

    Guided motion of vortices in the Nb films on a faceted Al sub 2 O sub 3 substrate is observed. Even and odd components of longitudinal and transverse magnetoresistivities of the samples with different orientation of transport current to the facet ridges are measured. The field inversion was used to separate the even and odd components of the measured magnetoresistivities.

  1. Stability of Geostrophic Vortices on a Rotating Sphere

    Science.gov (United States)

    1974-12-01

    equal strengh \\i equally spaced on a circle of colatitude 6, one vortex with strength u« at the pole; (c) the same distribution as in (a) but...N+l Vortices, No Boundary Condition at Equator. The formulas (2.1), (2.2) are inserted into (1.3), (1.4), (1.5). By expanding in powers of C

  2. A computational study of the effects of inlet guide vanes on the performance of a centrifugal blood pump.

    Science.gov (United States)

    Chan, W K; Wong, Y W; Yu, S C M; Chua, L P

    2002-06-01

    This article presents computational studies on the effects of inlet guide vanes (IGVs) on the flow pattern and shear stress in a centrifugal blood pump. The effect of IGVs is to introduce a pre-swirl to fluid particles entering the impeller with the intention that the fluid particles will travel along the blade profile. Currently, most commercial centrifugal blood pumps employ straight radial impeller blades that are not hydrodynamically ideal for a good flow pattern within the blade passage. Flow separation and formation of vortices within the blade passage are believed to increase the degree of hemolysis and thrombosis. These are causes for blood clotting that will lead to malfunctioning of ventricular assist devices. Four IGVs of different geometrical profiles have been numerically investigated using a commercial software program CFX-Tascflow. The pump is operated at 2,000 rpm, and the results revealed that the relative flow patterns in the blade passage have been dramatically altered. The size of the vortices was reduced, and the pressure contours indicated a gradual rise from the impeller leading edge to the trailing edge. However, inclusion of IGV causes a drop in the pressure head generated. Higher frictional losses are incurred as fluid particles passed through the IGV. In addition, the IGV modifies the inlet velocity triangles, and this also contributes to a drop in the pressure head generated that is consistent with Euler's pump theory. The change in the flow patterns and the gradual variation of the pressure contours have led to lower shear stress within the blade passages as compared to the case without IGVs.

  3. The life-cycle of Riemann-Silberstein electromagnetic vortices

    Science.gov (United States)

    Nye, J. F.

    2017-11-01

    To study the singularities of a monochromatic electromagnetic wave field in free space, it is desirable to use a quantity that combines both the electric field E and the magnetic field B in equal measure. The Riemann-Silberstein (R-S) field is a way of doing this. It is based on the real physical E and B and one constructs from them the complex vector field {F}={E}+{{i}} {B}. Then, one constructs {F}\\cdot {F} and studies the optical vortices of this R-S complex scalar field. Unlike the better-known and much studied optical vortices of a monochromatic complex scalar field, which are stationary, these vortices are normally in continual motion; they oscillate at the optical frequency. We study their life cycle in the simplest model that is sufficiently generic, namely, fields generated by the interference of four randomly chosen plane elliptically polarised waves. The topological events in the life cycle do not repeat on a 3D space lattice in a stationary laboratory frame. In space-time, however, the R-S vortices are invariant under any Lorentz transformation, and because of this and the inherent time repetition there is a particular moving frame in space-time, reached by a Lorentz transformation, where there exists a repeating pattern of events in space. Its 4D unit cell constitutes, in effect, a description of the whole infinite pattern. Just because they are in constant motion, it is not surprising that the R-S vortex lines in the model make reconnections and appear as rings that either shrink to nothing or appear from nothing. However, these processes occur in groups of four, reflecting the fact that the unit cell is face-centred. What distinguishes the R-S field from the other complex scalar fields containing vortices is the existence of this face-centred repeating cell.

  4. Lagrangian investigations of vorticity dynamics in compressible turbulence

    Science.gov (United States)

    Parashar, Nishant; Sinha, Sawan Suman; Danish, Mohammad; Srinivasan, Balaji

    2017-10-01

    In this work, we investigate the influence of compressibility on vorticity-strain rate dynamics. Well-resolved direct numerical simulations of compressible homogeneous isotropic turbulence performed over a cubical domain of 10243 are employed for this study. To clearly identify the influence of compressibility on the time-dependent dynamics (rather than on the one-time flow field), we employ a well-validated Lagrangian particle tracker. The tracker is used to obtain time correlations between the instantaneous vorticity vector and the strain-rate eigenvector system of an appropriately chosen reference time. In this work, compressibility is parameterized in terms of both global (turbulent Mach number) and local parameters (normalized dilatation-rate and flow field topology). Our investigations reveal that the local dilatation rate significantly influences these statistics. In turn, this observed influence of the dilatation rate is predominantly associated with rotation dominated topologies (unstable-focus-compressing, stable-focus-stretching). We find that an enhanced dilatation rate (in both contracting and expanding fluid elements) significantly enhances the tendency of the vorticity vector to align with the largest eigenvector of the strain-rate. Further, in fluid particles where the vorticity vector is maximally misaligned (perpendicular) at the reference time, vorticity does show a substantial tendency to align with the intermediate eigenvector as well. The authors make an attempt to provide physical explanations of these observations (in terms of moment of inertia and angular momentum) by performing detailed calculations following tetrads {approach of Chertkov et al. ["Lagrangian tetrad dynamics and the phenomenology of turbulence," Phys. Fluids 11(8), 2394-2410 (1999)] and Xu et al. ["The pirouette effect in turbulent flows," Nat. Phys. 7(9), 709-712 (2011)]} in a compressible flow field.

  5. Potential vorticity of the south polar vortex of Venus

    Science.gov (United States)

    Garate-Lopez, I.; Hueso, R.; Sánchez-Lavega, A.; García Muñoz, A.

    2016-04-01

    Venus' atmosphere shows highly variable warm vortices over both of the planet's poles. The nature of the mechanism behind their formation and properties is still unknown. Potential vorticity is a conserved quantity when advective processes dominate over friction and diabatic heating and is a quantity frequently used to model balanced flows. As a step toward understanding the vortices' dynamics, we present maps of Ertel's potential vorticity (EPV) at Venus' south polar region. We analyze three configurations of the south polar vortex at the upper cloud level (P ~ 240 mbar; z ~ 58 km), based on our previous analyses of cloud motions and thermal structure from data acquired by the Visual and InfraRed Thermal Imaging Spectrometer instrument on board Venus Express. Additionally, we tentatively estimate EPV at the lower cloud level (P ~ 2200 mbar; z ~ 43 km), based on our previous wind measurements and on static stability data from Pioneer Venus and the Venus International Reference Atmosphere (VIRA) model. Values of EPV are on the order of 10-6 and 10-8 K m2 kg-1 s-1 at the upper and lower cloud levels, respectively, being 3 times larger than the estimated errors. The morphology observed in EPV maps is mainly determined by the structures of the vertical component of the relative vorticity. This is in contrast to the vortex's morphology observed in 3.8 or 5 µm images which are related to the thermal structure of the atmosphere at the cloud top. Some of the EPV maps point to a weak ringed structure in the upper cloud, while a more homogenous EPV field is found in the lower cloud.

  6. On the evaluation of vorticity using cardiovascular magnetic resonance velocity measurements.

    Science.gov (United States)

    Garcia, J; Larose, E; Pibarot, P; Kadem, L

    2013-12-01

    Vorticity and vortical structures play a fundamental role affecting the evaluation of energetic aspects (mainly left ventricle work) of cardiovascular function. Vorticity can be derived from cardiovascular magnetic resonance (CMR) imaging velocity measurements. However, several numerical schemes can be used to evaluate the vorticity field. The main objective of this work is to assess different numerical schemes used to evaluate the vorticity field derived from CMR velocity measurements. We compared the vorticity field obtained using direct differentiation schemes (eight-point circulation and Chapra) and derivate differentiation schemes (Richardson 4* and compact Richardson 4*) from a theoretical velocity field and in vivo CMR velocity measurements. In all cases, the effect of artificial spatial resolution up-sampling and signal-to-noise ratio (SNR) on vorticity computation was evaluated. Theoretical and in vivo results showed that the eight-point circulation method underestimated vorticity. Up-sampling evaluation showed that the artificial improvement of spatial resolution had no effect on mean absolute vorticity estimation but it affected SNR for all methods. The Richardson 4* method and its compact version were the most accurate and stable methods for vorticity magnitude evaluation. Vorticity field determination using the eight-point circulation method, the most common method used in CMR, has reduced accuracy compared to other vorticity schemes. Richardson 4* and its compact version showed stable SNR using both theoretical and in vivo data.

  7. Spatial-temporal and modal analysis of propeller induced ground vortices by particle image velocimetry

    NARCIS (Netherlands)

    Yang, Y.; Sciacchitano, A.; Veldhuis, L.L.M.; Eitelberg, G.

    2016-01-01

    During the ground operation of aircraft, there is potentially a system of vortices generated from the ground toward the propulsor, commonly denoted as ground vortices. Although extensive research has been conducted on ground vortices induced by turbofans which were simplified by suction tubes, these

  8. Moderate Alcohol Consumption Is Associated With Left Ventricular Diastolic Dysfunction in Nonalcoholic Hypertensive Patients.

    Science.gov (United States)

    Catena, Cristiana; Colussi, GianLuca; Verheyen, Nicolas D; Novello, Marileda; Fagotto, Valentina; Soardo, Giorgio; Sechi, Leonardo A

    2016-11-01

    Ethanol consumption is associated with left ventricular dysfunction in heavy ethanol drinkers. The effect of moderate ethanol intake on left ventricular function in hypertension, however, is unknown. We investigated the relationship between ethanol consumption and cardiac changes in nonalcoholic hypertensive patients. In 335 patients with primary hypertension, we assessed daily ethanol consumption by questionnaires that combined evaluation of recent and lifetime ethanol exposure and examined cardiac structure and function by echocardiography. Patients with abnormal liver tests, previous cardiovascular events, left ventricular ejection fraction consumption was comparable in hypertensive patients with and without left ventricular hypertrophy, whereas patients with left ventricular diastolic dysfunction had significantly greater consumption than patients with normal ventricular filling. Left atrial diameter, e' wave velocity, e'/a' ratio, and E/e' ratio changed progressively with increasing levels of ethanol consumption, and prevalence of left ventricular diastolic dysfunction increased with a change that became statistically significant in patients consuming 20 g/d of ethanol or more. The e' wave velocity was inversely correlated with ethanol consumption, and multivariate logistic regression indicated that ethanol consumption predicted diastolic dysfunction independently of age, body mass index, blood pressure, insulin sensitivity, and left ventricular mass index. In conclusion, ethanol consumption is independently associated with left ventricular diastolic dysfunction in nonalcoholic hypertensive patients and might contribute to development of diastolic heart failure. © 2016 American Heart Association, Inc.

  9. [Late potentials and ventricular arrhythmia].

    Science.gov (United States)

    Adamec, R; Zimmermann, M

    1986-04-01

    When electrodes are placed at the surface of the thorax, high-amplification electrocardiography (HA-ECG) combined with signal summation as a function of time provides a non-invasive method for detecting electric potentials occurring after the QRS complex of the clinical electrocardiogram. These potentials are called late, and can probably be likened to the "divided" or "fragmented" potentials recorded directly on the heart or in its ventricles near zones of ischemia, infarction or aneurysm. The prevalence of late potentials of ventricular activation (LPVA) and their association with the occurrence of ventricular arrhythmias seems well established, notably in the presence of ventricular aneurysm and anamnesis of severe ventricular arrhythmia. Some studies have shown that detection of LPVAs is of value in identifying heart patients at risk of ventricular arrhythmia or sudden death. Heart disease aside, the presence of LPVAs has been demonstrated in arrhythmogenic right ventricular dysplasia and reported in Fallot's tetralogy after complete correction. A standardization of recordings and a more precise definition of LPVAs are necessary before HA-ECG can become a routine clinical method. Further, the possibility of "beat by beat" recordings with "spatial" summation will allow detection of LPVAs which vary with time and in nature and hence provide a better understanding of the genesis of ventricular arrhythmias.

  10. Cardiogenic shock: management of right ventricular infarction shock.

    Science.gov (United States)

    Ruiz Bailén, M; Ruiz García, M I; Ferrezuelo Mata, A; Quirós Barrera, R

    2012-04-01

    Right ventricular infarction is a not uncommon cause of cardiogenic shock, whose frecuency is variable and could be underestimated. Although left ventricular myocardial management is well defined in the right ventricular infarction are few studies with low level of evidence, to establish definitive guidelines. It is assumed that the treatment is similar to that of the left ventricle, although there are some differences. The axis of the therapeutic management, as well as the left ventricle infarction, is based on early myocardial reperfusion, particularly through percutaneous coronary interventionism. Throm-bolysis is an option, especially after an increase in systemic blood pressure using vasoactive drugs such as norepinephrine. The preload optimization by volume administration during resuscitation of shock is useful, but it must be with caution. The use of levosimendan could be potentially beneficial option. On the neurohormonal modulation of systemic inflammatory response produced after the cardiogenic shock (CS), the use of ACE inhibitors and beta-blockers is controversial.

  11. Growth and wall-transpiration control of nonlinear unsteady Görtler vortices forced by free-stream vortical disturbances

    Science.gov (United States)

    Marensi, Elena; Ricco, Pierre

    2017-11-01

    The generation, nonlinear evolution, and wall-transpiration control of unsteady Görtler vortices in an incompressible boundary layer over a concave plate is studied theoretically and numerically. Görtler rolls are initiated and driven by free-stream vortical perturbations of which only the low-frequency components are considered because they penetrate the most into the boundary layer. The formation and development of the disturbances are governed by the nonlinear unsteady boundary-region equations with the centrifugal force included. These equations are subject to appropriate initial and outer boundary conditions, which account for the influence of the upstream and free-stream forcing in a rigorous and mutually consistent manner. Numerical solutions show that the stabilizing effect on nonlinearity, which also occurs in flat-plate boundary layers, is significantly enhanced in the presence of centrifugal forces. Sufficiently downstream, the nonlinear vortices excited at different free-stream turbulence intensities Tu saturate at the same level, proving that the initial amplitude of the forcing becomes unimportant. At low Tu, the disturbance exhibits a quasi-exponential growth with the growth rate being intensified for more curved plates and for lower frequencies. At higher Tu, in the typical range of turbomachinery applications, the Görtler vortices do not undergo a modal stage as nonlinearity saturates rapidly, and the wall curvature does not affect the boundary-layer response. Good quantitative agreement with data from direct numerical simulations and experiments is obtained. Steady spanwise-uniform and spanwise-modulated zero-mass-flow-rate wall transpiration is shown to attenuate the growth of the Görtler vortices significantly. A novel modified version of the Fukagata-Iwamoto-Kasagi identity, used for the first time to study a transitional flow, reveals which terms in the streamwise momentum balance are mostly affected by the wall transpiration, thus

  12. Vorticity and upscaled dispersion in 3D heterogeneous porous media

    Science.gov (United States)

    Di Dato, Mariaines; Chiogna, Gabriele; de Barros, Felipe; Bellin, Alberto; Fiori, Aldo

    2015-04-01

    Modeling flow in porous media is relevant for many environmental, energy and industrial applications. From an environmental perspective, the relevance of porous media flow becomes evident in subsurface hydrology. In general, flow in natural porous media is creeping, yet the large variability in the hydraulic conductivity values encountered in natural aquifers leads to highly heterogeneous flow fields. This natural variability in the conductivity field will affect both dilution rates of chemical species and reactive mixing. A physical consequence of this heterogeneity is also the presence of a various localized kinematical features such as straining, shearing and vorticity in aquifers, which will influence the shape of solute clouds and its fate and transport. This work aims in fundamentally characterizing the vorticity field in spatially heterogeneous flow fields as a function of their statistical properties in order to analyze the impact on transport processes. In our study, three-dimensional porous formations are constructed with an ensemble of N independent, non-overlapping spheroidal inclusions submerged into an homogeneous matrix, of conductivity K0. The inclusions are randomly located in a domain of volume W and are fully characterized by the geometry of spheroid (oblate or prolate), their conductivity K (random and drawn from a given probability density function fκ), the centroid location ¯x, the axes ratio e, the orientation of the rotational axis (α1,α2) and the volume w. Under the assumption of diluted medium, the flow problem is solved analitically by means of only two parameters: the conductivity contrast κ = K/K0 and the volume fraction n = Nw/W . Through the variation of these parameters of the problem, it is possible to approximate the structure of natural heterogeneous porous media. Using a random distribution of the orientation of the inclusions, we create media defined by the same global anisotropy f = Iz/Ix but different micro

  13. Vortices and other topological solitons in dense quark matter

    Science.gov (United States)

    Eto, Minoru; Hirono, Yuji; Nitta, Muneto; Yasui, Shigehiro

    2014-01-01

    Dense quantum chromodynamic matter accommodates various kind of topological solitons such as vortices, domain walls, monopoles, kinks, boojums, and so on. In this review, we discuss various properties of topological solitons in dense quantum chromodynamics (QCD) and their phenomenological implications. Particular emphasis is placed on the topological solitons in the color-flavor-locked (CFL) phase, which exhibits both superfluidity and superconductivity. The properties of topological solitons are discussed in terms of effective field theories such as the Ginzburg-Landau theory, the chiral Lagrangian, or the Bogoliubov-de Gennes equation. The most fundamental string-like topological excitations in the CFL phase are non-Abelian vortices, which are 1/3 quantized superfluid vortices and color magnetic flux tubes. These vortices are created at a phase transition by the Kibble-Zurek mechanism or when the CFL phase is realized in compact stars, which rotate rapidly. The interaction between vortices is found to be repulsive and consequently a vortex lattice is formed in rotating CFL matter. Bosonic and fermionic zero-energy modes are trapped in the core of a non-Abelian vortex and propagate along it as gapless excitations. The former consists of translational zero modes (a Kelvin mode) with a quadratic dispersion and {mathbb {C}}P^2 Nambu-Goldstone gapless modes with a linear dispersion, associated with the CFL symmetry spontaneously broken in the core of a vortex, while the latter is Majorana fermion zero modes belonging to the triplet of the symmetry remaining in the core of a vortex. The low-energy effective theory of the bosonic zero modes is constructed as a non-relativistic free complex scalar field and a relativistic {mathbb {C}}P^2 model in 1+1 dimensions. The effects of strange quark mass, electromagnetic interactions, and non-perturbative quantum corrections are taken into account in the {mathbb {C}}P^2 effective theory. Various topological objects associated

  14. Systolic left ventricular function according to left ventricular concentricity and dilatation in hypertensive patients

    DEFF Research Database (Denmark)

    Bang, Casper; Gerdts, Eva; Aurigemma, Gerard P

    2013-01-01

    Left ventricular hypertrophy [LVH, high left ventricular mass (LVM)] is traditionally classified as concentric or eccentric based on left ventricular relative wall thickness. We evaluated left ventricular systolic function in a new four-group LVH classification based on left ventricular dilatatio...

  15. Discretization of the vorticity field of a planar jet

    Science.gov (United States)

    Ross, Natalie; Hertzberg, Jean; Bradley, Elizabeth

    2010-11-01

    In data assimilation, information from sensors is used to correct the state variables of a numerical model. This has been used to great advantage by the weather prediction community in the context of direct numerical simulation (DNS) models, but has seen comparatively little use in point-vortex models. This is due in large part to data-processing issues. In order to keep up with the speeds necessary for effective data assimilation, one must extract and discretize the vortex structures from velocity field data in a computationally efficient fashion—i.e., using as few discrete vortices as possible to model the measured flow. This paper describes a new strategy for accomplishing this and evaluates the results using data from a laboratory-scale vortex-dominated planar jet. Large-scale vortex structures are found using a family of variants on traditional vortex extraction methods. By augmenting these methods with simple computational topology techniques, one obtains a new method that finds the boundaries of the coherent structures in a manner that naturally follows the geometry of the flow. This strategy was evaluated in the context of two standard vortex extraction methods, vorticity thresholding and Okubo-Weiss, and tested upon velocity field data from the experimental fluid flow. The large-scale structures found in this manner were then modeled with collections of discrete vortices, and the effects of the grain size of the discretization and the parameters of the discrete vortex model were studied. The results were evaluated by comparing the instantaneous velocity field induced by the discrete vortices to that measured in the jet. These comparisons showed that the two extraction techniques were comparable in terms of sensitivity and error, suggesting that the computationally simpler vorticity thresholding method is more appropriate for applications where speed is an issue, like data assimilation. Comparisons of different discretization strategies showed that

  16. [Ventricular tachycardia and cardiac hemochromatosis].

    Science.gov (United States)

    Luis Moríñigo, J; Martín Luengo, C; Ledesma, C; Arribas, A; Nieto, A A; Rodríguez, J

    2001-11-01

    Hemochromatosis is characterized by an excessive iron deposit in different tissues. Cardiac involvement may be observed in one third of the patients due to hemochromatosis and occurs as a consequence of ferritin accumulation in the heart which on one hand induces alterations in systolic and diastolic ventricular function and on the other hand, an arrythmogenic substrate. The clinical manifestations can be indistinctly related to atrial tachyarrhythmia, ventricular tachyarrhythmia, atrio-ventricular blockade and congestive heart failure, with the first being the most frequent. We present the case of one patient with secondary hemochromatosis to repeated transfusions due to sideroblastic anemia with cardiac involvement, whose initial heart manifestations were recurrent atrial tachyarrhythmia and sustained ventricular tachycardia with syncope for which an automatic defibrillator was implanted.

  17. Nonlinear dynamics in ventricular fibrillation.

    Science.gov (United States)

    Hastings, H M; Evans, S J; Quan, W; Chong, M L; Nwasokwa, O

    1996-09-17

    Electrogram recordings of ventricular fibrillation appear complex and possibly chaotic. However, sequences of beat-to-beat intervals obtained from these recordings are generally short, making it difficult to explicitly demonstrate nonlinear dynamics. Motivated by the work of Sugihara on atmospheric dynamics and the Durbin-Watson test for nonlinearity, we introduce a new statistical test that recovers significant dynamical patterns from smoothed lag plots. This test is used to show highly significant nonlinear dynamics in a stable canine model of ventricular fibrillation.

  18. Vorticity budget investigation of a simulated long-lived mesoscale vortex in South China

    Science.gov (United States)

    Chen, Min; Zheng, Yongguang

    2004-12-01

    A vorticity budget investigation is performed using the output data from a numerical simulation of a typical MCV (mesoscale convectively generated votex) case in South China. Results suggest that the divergence caused by convection in the low troposphere is the main producer of positive vorticity, while vertical vorticity transferred by the tilting term from the horizontal vorticity compensates the upward output of cyclonic vorticity. Scale analyses of the vorticity equation suggest that the advection of planetary vorticity can be neglected owing to the low latitude, which is different from the larger scale systems in high latitude areas. In addition, the distribution of relative vorticity tendency on pressure level is not uniform. A vortex will move along the vector from the negative to the positive vorticity tendency region. The mechanism of the phenomenon—that nearly all of the convectively ascending region is located southward/southeastward of the vortex center—is also discussed. Convergence with regard to latent heat release would be in favor of the spin-up of meso-vortex, however, the horizontal vorticity caused by wind shear is tilted by vertical motion due to convection. Consequently, the negative and positive vorticity tendencies are located symmetrically about the convective center, which suggests that the vortex southward movement is dynamically driven by convection.

  19. Spanwise Spacing Effects on the Initial Structure and Decay of Axial Vortices

    Science.gov (United States)

    Wendt, B. J.; Reichert, B. A.

    1996-01-01

    The initial structure and axial decay of an array of streamwise vortices embedded in a turbulent pipe boundary layer is experimentally investigated. The vortices are shed in counter-rotating fashion from an array of equally-spaced symmetric airfoil vortex generators. Vortex structure is quantified in terms of crossplane circulation and peak streamwise vorticity. Flow conditions are subsonic and incompressible. The focus of this study is on the effect of the initial spacing between the parent vortex generators. Arrays with vortex generators spaced at 15 and 30 degrees apart are considered. When the spacing between vortex generators is decreased the circulation and peak vorticity of the shed vortices increases. Analysis indicates this strengthening results from regions of fluid acceleration in the vicinity of the vortex generator array. Decreased spacing between the constituent vortices also produces increased rates of circulation and peak vorticity decay.

  20. Numerical study of the evolution of vortices in a linearly stratified fluid

    Energy Technology Data Exchange (ETDEWEB)

    Beckers, M.; Clercx, H.J.H.; Van Heijst, G.J.F. [Eindhoven University of Technology, Eindhoven (Netherlands). J.M. Burgers Centre fro Fluid Dynamics; Verzicco, R. [Rome Univ. La Sapienza, Rome (Italy). Dipt. di Meccanica e Aeronautica

    1999-12-01

    This paper presents a numerical study in which the evolution of vortices in a Stafford fluid is compared to the evolution of two-dimensional vortices. The influence of the Reynolds number and the Froude number are investigated, for the evolution of axisymmetric vortices, for their azimuthal instability and for the subsequent formation of tripoles. It is found that due to radial diffusion axisymmetric vortices with various initial vorticity profiles all evolve towards the same profile. This evolution reduces the growth of azimuthal instabilities which may lead to the formation of a tripole. For vortices in a stratified fluid the effect of the ambient stratification on the evolution of the vortices is investigated. It is found that a process of vortex stretching, which becomes more pronounced for increasing Froude numbers, leads to a weaker tripole formation.

  1. Ventricular arrhythmias in Chagas disease

    Directory of Open Access Journals (Sweden)

    Marco Paulo Tomaz Barbosa

    2015-02-01

    Full Text Available Sudden death is one of the most characteristic phenomena of Chagas disease, and approximately one-third of infected patients develop life-threatening heart disease, including malignant ventricular arrhythmias. Fibrotic lesions secondary to chronic cardiomyopathy produce arrhythmogenic substrates that lead to the appearance and maintenance of ventricular arrhythmias. The objective of this study is to discuss the main clinical and epidemiological aspects of ventricular arrhythmias in Chagas disease, the specific workups and treatments for these abnormalities, and the breakthroughs needed to determine a more effective approach to these arrhythmias. A literature review was performed via a search of the PubMed database from 1965 to May 31, 2014 for studies of patients with Chagas disease. Clinical management of patients with chronic Chagas disease begins with proper clinical stratification and the identification of individuals at a higher risk of sudden cardiac death. Once a patient develops malignant ventricular arrhythmia, the therapeutic approach aims to prevent the recurrence of arrhythmias and sudden cardiac death by the use of implantable cardioverter defibrillators, antiarrhythmic drugs, or both. In select cases, invasive ablation of the reentrant circuit causing tachycardia may be useful. Ventricular arrhythmias are important manifestations of Chagas cardiomyopathy. This review highlights the absence of high-quality evidence regarding the treatment of ventricular arrhythmias in Chagas disease. Recognizing high-risk patients who require specific therapies, especially invasive procedures such as the implantation of cardioverter defibrillators and ablative approaches, is a major challenge in clinical practice.

  2. [Echocardiographic study of left ventricular geometry in spontaneously hypertensive rats].

    Science.gov (United States)

    Escudero, Eduardo M; Pinilla, Oscar A; Carranza, Verónica B

    2009-01-01

    The purpose of this study was to analyze by echocardiogram left ventricular (LV) geometry in spontaneously hypertensive rats (SHR). Echocardiographic study, systolic blood pressure and heart rate were obtained in 114 male, 4-month old rats, 73 SHR and 41 Wistar (W). Left ventricular mass index (LVMI), relative wall thickness (RWT), stroke volume, and mid ventricular shortening were calculated with echocardiographic parameters. Normal LV was defined considering the mean plus 2 SD of LVMI and RWT in W. Patterns of abnormal LV geometry were: LV concentric remodeling, LVMI 0.71; eccentric, left ventricular hypertrophy (LVH), LVMI > 2.06 mg/g - RWT 2.06 mg/g - RWT > 0.71. Systolic blood pressure (SBP) and cardiac output (CO) were used to obtain total peripheral resistance (TPR). twelve % of SHR had normal LV geometry; 18% LV concentric remodeling; 33% concentric LVH and 37% eccentric LVH. LV concentric remodeling showed the smallest CO and highest TPR of any group. Eccentric LVH presented similar SBP as the other SHR groups and high CO with lower TPR. Our findings in SHR exhibit different patterns of LV geometry like in humans. These results strengthen the similarities between SHR and human essential hypertension.

  3. Echocardiographic assessment of the different left ventricular geometric patterns in hypertensive patients

    Directory of Open Access Journals (Sweden)

    Delma Maria Cunha

    2001-01-01

    Full Text Available OBJECTIVE: To identiy left ventricular geometric patterns in hypertensive patients on echocardiography, and to correlate those patterns with casual blood pressure measurements and with the parameters obtained on a 24-hour ambulatory blood pressure monitoring. METHODS: We studied sixty hypertensive patients, grouped according to the Joint National Committee stages of hypertension.. Using the single- and two-dimensional Doppler Echocardiography, we analyzed the left ventricular mass and the geometric patterns through the correlation of left ventricular mass index and relative wall thickness. On ambulatory blood pressure monitoring we assessed the means and pressure loads in the different geometric patterns detected on echocardiography RESULTS: We identified three left ventricular geometric patterns: 1 concentric hypertrophy, in 25% of the patients; 2 concentric remodeling, in 25%; and 3 normal geometry, in 50%. Casual systolic blood pressure was higher in the group with concentric hypertrophy than in the other groups (p=0.001. Mean systolic pressure in the 24h, daytime and nighttime periods was also higher in patients with concentric hypertrophy, as compared to the other groups (p=0.003, p=0.004 and p=0.007. Daytime systolic load and nighttime diastolic load were higher in patients with concentric hypertrophy ( p=0.004 and p=0.01, respectively. CONCLUSIONS: Left ventricular geometric patterns show significant correlation with casual systolic blood pressure, and with means and pressure loads on ambulatory blood pressure monitoring.

  4. 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 ...

  5. Fractional vortices in the XY model with {pi} bonds

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, R. V.; Almaas, E.; Fisher, K. D.; Stroud, D.

    2000-11-01

    We define a new set of excitations in the XY model which we call ''fractional vortices.'' In the frustrated XY model containing {pi} bonds, we make the ansatz that the ground state configurations can be characterized by pairs of oppositely charged fractional vortices. For a chain of {pi} bonds, the ground state energy and the phase configurations calculated on the basis of this ansatz agree well with the results from direct numerical simulations. Finally, we discuss the possible connection of these results to some recent experiments by Kirtley [Phys. Rev. B 51, R12057 (1995)] on high-T{sub c} superconductors where fractional flux trapping was observed along certain grain boundaries.

  6. Neutrino induced vorticity, Alfven waves and the normal modes

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Jitesh R. [Theory Division, Physical Research Laboratory, Ahmedabad (India); George, Manu [Theory Division, Physical Research Laboratory, Ahmedabad (India); Indian Institute of Technology, Department of Physics, Ahmedabad (India)

    2017-08-15

    We consider a plasma consisting of electrons and ions in the presence of a background neutrino gas and develop the magnetohydrodynamic equations for the system. We show that the electron neutrino interaction can induce vorticity in the plasma even in the absence of any electromagnetic perturbations if the background neutrino density is left-right asymmetric. This induced vorticity supports a new kind of Alfven wave whose velocity depends on both the external magnetic field and on the neutrino asymmetry. The normal mode analysis show that in the presence of neutrino background the Alfven waves can have different velocities. We also discuss our results in the context of dense astrophysical plasma such as magnetars and show that the difference in the Alfven velocities can be used to explain the observed pulsar kick. We discuss also the relativistic generalisation of the electron fluid in presence of an asymmetric neutrino background. (orig.)

  7. Formation of optical vortices through superposition of two Gaussian beams.

    Science.gov (United States)

    Vaity, Pravin; Aadhi, A; Singh, R P

    2013-09-20

    We observe phase singularities in the superposed field of two Gaussian beams. It is seen that the formation of these singularities depends on the tilt between two Gaussian beams and the separation of their beam axes. By reversing the angle or the position of the beams, one can change the sign of the vortex. We have shown the formation of single as well as multiple vortices by changing the tilt angle and the position of two Gaussian beams. The experimental results are verified with theoretical analysis. We also observe that such a vortex structure can be formed through superposition of two backreflected Gaussian beams from any optical element with two flat surfaces, as illustrated through a beam splitter and a neutral density filter. This technique is very useful for generation of vortices with high-power lasers where one cannot use a spatial light modulator.

  8. Measurement of secondary flow vortices on a rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Vonka, V.

    1988-02-01

    Secondary flow vortices in infinite rod bundles have been predicted by a number of theoretical analyses. Nevertheless experimental verification was difficult, since the magnitude of the secondary velocities appeared to be less than the accuracy of the experimental techniques used. Only indications of the maximum velocity magnitude have been available but no report on successful direct measurement is known to the author. At ECN, laser Doppler velocimetry is successfully used for measurement of secondary flow vortices in two regular subchannels of a triangularly arranged bare rod bundle with pitch-to-diameter ratio P/D-1.3 under the Reynolds number conditions 60,000 and 175,000. One single secondary vortex, having the average tangential velocity slightly less than 0.1% of the mean bulk velocity, is resolved per minimum symmetry sector of the bundle geometry. Ensemble averages are made to obtain quantitative description of the vortex and to form a data base for comparison with calculations.

  9. Mixing and coherent vortices in turbulent coaxial jets

    Science.gov (United States)

    Balarac, Guillaume; Si-Ameur, Mohamed

    2005-08-01

    Direct numerical simulations associated with mixing in constant-density round coaxial jets are performed. They are validated by comparison against laboratory experiments. The mixing process is studied by seeding a passive tracer first in the outer annular jet, then in the inner jet. We demonstrate the important role played by coherent vortices in the mixing mechanisms. The turbulent mixing exhibits an intermittent character as a consequence of fluid ejections caused by the counter-rotating streamwise vortices. We quantify also the domination of the outer jet and show that the fluid issuing from the central jet remains confined. To cite this article: G. Balarac, M. Si-Ameur, C. R. Mecanique 333 (2005).

  10. Helicity conservation and twisted Seifert surfaces for superfluid vortices

    Science.gov (United States)

    Salman, Hayder

    2017-04-01

    Starting from the continuum definition of helicity, we derive from first principles its different contributions for superfluid vortices. Our analysis shows that an internal twist contribution emerges naturally from the mathematical derivation. This reveals that the spanwise vector that is used to characterize the twist contribution must point in the direction of a surface of constant velocity potential. An immediate consequence of the Seifert framing is that the continuum definition of helicity for a superfluid is trivially zero at all times. It follows that the Gauss-linking number is a more appropriate definition of helicity for superfluids. Despite this, we explain how a quasi-classical limit can arise in a superfluid in which the continuum definition for helicity can be used. This provides a clear connection between a microscopic and a macroscopic description of a superfluid as provided by the Hall-Vinen-Bekarevich-Khalatnikov equations. This leads to consistency with the definition of helicity used for classical vortices.

  11. Left ventricular noncompaction.

    Science.gov (United States)

    Ichida, Fukiko

    2009-01-01

    Left ventricular noncompaction (LVNC) is a recently defined cardiomyopathy characterized by a pattern of prominent trabecular meshwork and deep intertrabecular recesses, and is thought to be caused by arrest of normal endomyocardial morphogenesis. Although LVNC has been classified as a primary cardiomyopathy of genetic origin, its definition and diagnostic criteria are still being debated. Isolated LVNC was thought to be rare; however, heightened awareness has resulted in an increased detection of the morphological features of LVNC in routine clinical practice, especially in the adult population. Clinical manifestations are highly variable, ranging from no symptoms to disabling congestive heart failure, arrhythmias, and systemic thromboemboli. LVNC, like other forms of inherited cardiomyopathy, is genetically heterogeneous and can be inherited as an autosomal-dominant or X-linked recessive disorder. It has been linked to mutations in several genes, including LIM domain binding protein 3 (ZASP), alpha-dystrobrevin (DTNA), tafazzin (TAZ/G4.5) and those encoding sarcomeric proteins. However, the relatively small contribution of known mutations to the disease, compared with the higher proportion of familial cases suggests that other elusive genes remain to be identified.

  12. Helicity and topology of a small region of quantum vorticity

    Science.gov (United States)

    Mesgarnezhad, M.; Cooper, R. G.; Baggaley, A. W.; Barenghi, C. F.

    2018-02-01

    We numerically study the evolution of a small turbulent region of quantised vorticity in superfluid helium, a regime which can be realised in the laboratory. We show that the turbulence achieves a fluctuating steady-state in terms of dynamics (energy), geometry (length, writhing) and topology (linking). We show that, at any instant, the turbulence consists of many unknots and few large loops of great geometrical and topological complexity.

  13. Structure and evolution of 3D Rossby Vortices

    Science.gov (United States)

    Richard, S.; Barge, P.

    2013-04-01

    Three dimensional compressible simulations of the Rossby Wave Instability are presented in a non-homentropic model of protoplanetary disk. The instability develops like in the two dimensional case, gradually coming to the formation of a single big vortex. This 3D vortex has a quasi-2D structure which looks like a vorticity column with only tiny vertical motions. The vortex survives hundred of rotations in a quasi-steady evolution and slowly migrates inward toward the star.

  14. Arrhythmogenic right ventricular dysplasia: Atypical clinical presentation.

    Science.gov (United States)

    Marçalo, José; Menezes Falcão, Luiz

    2017-03-01

    A 67-year-old man was admitted to our hospital after episodes of syncope preceded by malaise and diffuse neck and chest discomfort. No family history of cardiac disease was reported. Laboratory workup was within normal limits, including D-dimers, serum troponin I and arterial blood gases. The electrocardiogram showed sinus rhythm with T-wave inversion in leads V1 to V3. Computed tomography angiography to investigate pulmonary embolism showed no abnormal findings. Transthoracic echocardiography (TTE) displayed massive enlargement of the right ventricle with intact interatrial septum and no pulmonary hypertension. Cardiac magnetic resonance imaging (MRI) confirmed right ventricular (RV) dilatation and revealed marked hypokinesia/akinesia of the lateral wall. Exercise stress testing was negative for ischemia. According to the 2010 Task Force criteria for arrhythmogenic right ventricular dysplasia (ARVD), this patient presented two major criteria (global or regional dysfunction and structural alterations: by MRI, regional RV akinesia or dyskinesia or dyssynchronous RV contraction and RV ejection fraction ≤40%, and repolarization abnormalities: inverted T waves in right precordial leads [V1, V2, and V3]); and one minor criterion (>500 ventricular extrasystoles per 24 hours by Holter), and so a diagnosis of ARVD was made. After electrophysiologic study (EPS) the patient received an implantable cardioverter-defibrillator (ICD). This late clinical presentation of ARVD highlights the importance of TTE screening, possibly complemented by MRI. The associated risk of sudden death was assessed by EPS leading to the implantation of an ICD. Genetic association studies should be offered to the offspring of all ARVD patients. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. The overloaded right heart and ventricular interdependence.

    Science.gov (United States)

    Naeije, Robert; Badagliacca, Roberto

    2017-10-01

    The right and the left ventricle are interdependent as both structures are nested within the pericardium, have the septum in common and are encircled with common myocardial fibres. Therefore, right ventricular volume or pressure overloading affects left ventricular function, and this in turn may affect the right ventricle. In normal subjects at rest, right ventricular function has negligible interaction with left ventricular function. However, the right ventricle contributes significantly to the normal cardiac output response to exercise. In patients with right ventricular volume overload without pulmonary hypertension, left ventricular diastolic compliance is decreased and ejection fraction depressed but without intrinsic alteration in contractility. In patients with right ventricular pressure overload, left ventricular compliance is decreased with initial preservation of left ventricular ejection fraction, but with eventual left ventricular atrophic remodelling and altered systolic function. Breathing affects ventricular interdependence, in healthy subjects during exercise and in patients with lung diseases and altered respiratory system mechanics. Inspiration increases right ventricular volumes and decreases left ventricular volumes. Expiration decreases both right and left ventricular volumes. The presence of an intact pericardium enhances ventricular diastolic interdependence but has negligible effect on ventricular systolic interdependence. On the other hand, systolic interdependence is enhanced by a stiff right ventricular free wall, and decreased by a stiff septum. Recent imaging studies have shown that both diastolic and systolic ventricular interactions are negatively affected by right ventricular regional inhomogeneity and prolongation of contraction, which occur along with an increase in pulmonary artery pressure. The clinical relevance of these observations is being explored. Published on behalf of the European Society of Cardiology. All rights

  16. Vortical ciliary flows actively enhance mass transport in reef corals.

    Science.gov (United States)

    Shapiro, Orr H; Fernandez, Vicente I; Garren, Melissa; Guasto, Jeffrey S; Debaillon-Vesque, François P; Kramarsky-Winter, Esti; Vardi, Assaf; Stocker, Roman

    2014-09-16

    The exchange of nutrients and dissolved gasses between corals and their environment is a critical determinant of the growth of coral colonies and the productivity of coral reefs. To date, this exchange has been assumed to be limited by molecular diffusion through an unstirred boundary layer extending 1-2 mm from the coral surface, with corals relying solely on external flow to overcome this limitation. Here, we present direct microscopic evidence that, instead, corals can actively enhance mass transport through strong vortical flows driven by motile epidermal cilia covering their entire surface. Ciliary beating produces quasi-steady arrays of counterrotating vortices that vigorously stir a layer of water extending up to 2 mm from the coral surface. We show that, under low ambient flow velocities, these vortices, rather than molecular diffusion, control the exchange of nutrients and oxygen between the coral and its environment, enhancing mass transfer rates by up to 400%. This ability of corals to stir their boundary layer changes the way that we perceive the microenvironment of coral surfaces, revealing an active mechanism complementing the passive enhancement of transport by ambient flow. These findings extend our understanding of mass transport processes in reef corals and may shed new light on the evolutionary success of corals and coral reefs.

  17. Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Auslaender, M.

    2010-05-25

    Superconductors often contain quantized microscopic whirlpools of electrons, called vortices, that can be modeled as one-dimensional elastic objects. Vortices are a diverse playground for condensed matter because of the interplay between thermal fluctuations, vortex-vortex interactions, and the interaction of the vortex core with the three-dimensional disorder landscape. While vortex matter has been studied extensively, the static and dynamic properties of an individual vortex have not. Here we employ magnetic force microscopy (MFM) to image and manipulate individual vortices in detwinned, single crystal YBa{sub 2}Cu{sub 3}O{sub 6.991} (YBCO), directly measuring the interaction of a moving vortex with the local disorder potential. We find an unexpected and dramatic enhancement of the response of a vortex to pulling when we wiggle it transversely. In addition, we find enhanced vortex pinning anisotropy that suggests clustering of oxygen vacancies in our sample and demonstrates the power of MFM to probe vortex structure and microscopic defects that cause pinning.

  18. Heat-Transfer Enhancement by Artificially Generated Streamwise Vorticity

    Science.gov (United States)

    Ghanem, Akram; Habchi, Charbel; Lemenand, Thierry; Della Valle, Dominique; Peerhossaini, Hassan

    2012-11-01

    Vortex-induced heat transfer enhancement exploits longitudinal and transverse pressure-driven vortices through the deliberate artificial generation of large-scale vortical flow structures. Thermal-hydraulic performance, Nusselt number and friction factor are experimentally investigated in a HEV (high-efficiency vortex) mixer, which is a tubular heat exchanger and static mixer equipped with trapezoidal vortex generators. Pressure gradients are generated on the trapezoidal tab initiating a streamwise swirling motion in the form of two longitudinal counter-rotating vortex pairs (CVP). Due to the Kelvin-Helmholtz instability, the shear layer generated at the tab edges, which is a production site of turbulence kinetic energy (TKE), becomes unstable further downstream from the tabs and gives rise to periodic hairpin vortices. The aim of the study is to quantify the effects of hydrodynamics on the heat- and masstransfer phenomena accompanying such flows for comparison with the results of numerical studies and validate the high efficiency of the intensification process implementing such vortex generators. The experimental results reflect the enhancement expected from the numerical studies and confirm the high status of the HEV heat exchanger and static mixer.

  19. Lagrangian structures in time-periodic vortical flows

    Directory of Open Access Journals (Sweden)

    S. V. Kostrykin

    2006-01-01

    Full Text Available The Lagrangian trajectories of fluid particles are experimentally studied in an oscillating four-vortex velocity field. The oscillations occur due to a loss of stability of a steady flow and result in a regular reclosure of streamlines between the vortices of the same sign. The Eulerian velocity field is visualized by tracer displacements over a short time period. The obtained data on tracer motions during a number of oscillation periods show that the Lagrangian trajectories form quasi-regular structures. The destruction of these structures is determined by two characteristic time scales: the tracers are redistributed sufficiently fast between the vortices of the same sign and much more slowly transported into the vortices of opposite sign. The observed behavior of the Lagrangian trajectories is quantitatively reproduced in a new numerical experiment with two-dimensional model of the velocity field with a small number of spatial harmonics. A qualitative interpretation of phenomena observed on the basis of the theory of adiabatic chaos in the Hamiltonian systems is given. The Lagrangian trajectories are numerically simulated under varying flow parameters. It is shown that the spatial-temporal characteristics of the Lagrangian structures depend on the properties of temporal change in the streamlines topology and on the adiabatic parameter corresponding to the flow. The condition for the occurrence of traps (the regions where the Lagrangian particles reside for a long time is obtained.

  20. Topological charge algebra of optical vortices in nonlinear interactions

    Science.gov (United States)

    Shutova, Mariia; Zhdanova, Alexandra; Bahari, Aysan; Zhi, Miaochan; Sokolov, Alexei

    2016-05-01

    Optical vortices find their use in multiple areas of research and technology; in particular, they provide an opportunity to generate short-pulse spatially-structured optical beams, which can be used to study ultrafast processes. In our work, we explore interactions of femtosecond optical vortices in nonlinear crystals. We investigate the transfer of orbital angular momentum among multiple (applied and generated) beams involved in a coherent Raman interaction. We use a liquid crystal light modulator to shape the applied pump and Stokes beams into optical vortices with various integer values of topological charge, and cross them in a Raman-active crystal to produce multiple Stokes and anti-Stokes sidebands. We then examine the transfer of optical angular momentum into each sideband and find that it follows a certain law that can be derived from angular momentum conservation for created and annihilated photons, or equivalently, from phase-matching considerations for the interacting beams. Presenter is supported by the Herman F. Heep and Minnie Belle Heep Texas A&M University Endowed Fund administered by the Texas A&M Foundation

  1. Generation of optical vortices in an integrated optical circuit

    Science.gov (United States)

    Tudor, Rebeca; Kusko, Mihai; Kusko, Cristian

    2017-09-01

    In this work, the generation of optical vortices in an optical integrated circuit is numerically demonstrated. The optical vortices with topological charge m = ±1 are obtained by the coherent superposition of the first order modes present in a waveguide with a rectangular cross section, where the phase delay between these two propagating modes is Δφ = ±π/2. The optical integrated circuit consists of an input waveguide continued with a y-splitter. The left and the right arms of the splitter form two coupling regions K1 and K2 with a multimode output waveguide. In each coupling region, the fundamental modes present in the arms of the splitter are selectively coupled into the output waveguide horizontal and vertical first order modes, respectively. We showed by employing the beam propagation method simulations that the fine tuning of the geometrical parameters of the optical circuit makes possible the generation of optical vortices in both transverse electric (TE) and transverse magnetic (TM) modes. Also, we demonstrated that by placing a thermo-optical element on one of the y-splitter arms, it is possible to switch the topological charge of the generated vortex from m = 1 to m = ‑1.

  2. Extreme-Ultraviolet Vortices from a Free-Electron Laser

    Directory of Open Access Journals (Sweden)

    Primož Rebernik Ribič

    2017-08-01

    Full Text Available Extreme-ultraviolet vortices may be exploited to steer the magnetic properties of nanoparticles, increase the resolution in microscopy, and gain insight into local symmetry and chirality of a material; they might even be used to increase the bandwidth in long-distance space communications. However, in contrast to the generation of vortex beams in the infrared and visible spectral regions, production of intense, extreme-ultraviolet and x-ray optical vortices still remains a challenge. Here, we present an in-situ and an ex-situ technique for generating intense, femtosecond, coherent optical vortices at a free-electron laser in the extreme ultraviolet. The first method takes advantage of nonlinear harmonic generation in a helical undulator, producing vortex beams at the second harmonic without the need for additional optical elements, while the latter one relies on the use of a spiral zone plate to generate a focused, micron-size optical vortex with a peak intensity approaching 10^{14}  W/cm^{2}, paving the way to nonlinear optical experiments with vortex beams at short wavelengths.

  3. The impact of intraglottal vortices on vocal fold dynamics

    Science.gov (United States)

    Erath, Byron; Pirnia, Alireza; Peterson, Sean

    2016-11-01

    During voiced speech a critical pressure is produced in the lungs that separates the vocal folds and creates a passage (the glottis) for airflow. As air passes through the vocal folds the resulting aerodynamic loading, coupled with the tissue properties of the vocal folds, produces self-sustained oscillations. Throughout each cycle a complex flow field develops, characterized by a plethora of viscous flow phenomena. Air passing through the glottis creates a jet, with periodically-shed vortices developing due to flow separation and the Kelvin-Helmholtz instability in the shear layer. These vortices have been hypothesized to be a crucial mechanism for producing vocal fold vibrations. In this study the effect of vortices on the vocal fold dynamics is investigated experimentally by passing a vortex ring over a flexible beam with the same non-dimensional mechanical properties as the vocal folds. Synchronized particle image velocimetry data are acquired in tandem with the beam dynamics. The resulting impact of the vortex ring loading on vocal fold dynamics is discussed in detail. This work was supported by the National Science Foundation Grant CBET #1511761.

  4. Machine learning vortices at the Kosterlitz-Thouless transition

    Science.gov (United States)

    Beach, Matthew J. S.; Golubeva, Anna; Melko, Roger G.

    2018-01-01

    Efficient and automated classification of phases from minimally processed data is one goal of machine learning in condensed-matter and statistical physics. Supervised algorithms trained on raw samples of microstates can successfully detect conventional phase transitions via learning a bulk feature such as an order parameter. In this paper, we investigate whether neural networks can learn to classify phases based on topological defects. We address this question on the two-dimensional classical XY model which exhibits a Kosterlitz-Thouless transition. We find significant feature engineering of the raw spin states is required to convincingly claim that features of the vortex configurations are responsible for learning the transition temperature. We further show a single-layer network does not correctly classify the phases of the XY model, while a convolutional network easily performs classification by learning the global magnetization. Finally, we design a deep network capable of learning vortices without feature engineering. We demonstrate the detection of vortices does not necessarily result in the best classification accuracy, especially for lattices of less than approximately 1000 spins. For larger systems, it remains a difficult task to learn vortices.

  5. Extreme-Ultraviolet Vortices from a Free-Electron Laser

    Science.gov (United States)

    Rebernik Ribič, Primož; Rösner, Benedikt; Gauthier, David; Allaria, Enrico; Döring, Florian; Foglia, Laura; Giannessi, Luca; Mahne, Nicola; Manfredda, Michele; Masciovecchio, Claudio; Mincigrucci, Riccardo; Mirian, Najmeh; Principi, Emiliano; Roussel, Eléonore; Simoncig, Alberto; Spampinati, Simone; David, Christian; De Ninno, Giovanni

    2017-07-01

    Extreme-ultraviolet vortices may be exploited to steer the magnetic properties of nanoparticles, increase the resolution in microscopy, and gain insight into local symmetry and chirality of a material; they might even be used to increase the bandwidth in long-distance space communications. However, in contrast to the generation of vortex beams in the infrared and visible spectral regions, production of intense, extreme-ultraviolet and x-ray optical vortices still remains a challenge. Here, we present an in-situ and an ex-situ technique for generating intense, femtosecond, coherent optical vortices at a free-electron laser in the extreme ultraviolet. The first method takes advantage of nonlinear harmonic generation in a helical undulator, producing vortex beams at the second harmonic without the need for additional optical elements, while the latter one relies on the use of a spiral zone plate to generate a focused, micron-size optical vortex with a peak intensity approaching 1014 W /cm2 , paving the way to nonlinear optical experiments with vortex beams at short wavelengths.

  6. Some exact BPS solutions for exotic vortices and monopoles

    Directory of Open Access Journals (Sweden)

    Handhika S. Ramadhan

    2016-07-01

    Full Text Available We present several analytical solutions of BPS vortices and monopoles in the generalized Abelian Maxwell–Higgs and Yang–Mills–Higgs theories, respectively. These models have recently been extensively studied and several exact solutions have already been obtained in [1,2]. In each theory, the dynamics is controlled by the additional two positive scalar-field-dependent functions, f(|ϕ| and w(|ϕ|. For the case of vortices, we work in the ordinary symmetry-breaking Higgs potential, while for the case of monopoles we have the ordinary condition of the Prasad–Sommerfield limit. Our results generalize the exact solutions found previously. We also present solutions for BPS vortices with higher winding number. These solutions suffer from the condition that w(|ϕ| has negative value at some finite range of r, but we argue that since it satisfies the weaker positive-value conditions then the corresponding energy density is still positive-definite and, thus, they are acceptable BPS solutions.

  7. Characterization of Surfaces and the Estimation of Shock Induced Vorticity

    Energy Technology Data Exchange (ETDEWEB)

    Jameson, L; Ray, J; Peyser, T

    2002-09-17

    When shocks impinge on a surface separating fluids of two different densities, one observes the development and growth of various vortical structures. The flow induced by this Richtmyer-Meshkov (RM) instability depends on a variety of factors such as the shock strength, the density ratio of the fluids and the exact form of the surface perturbation. The most common way to model the form of the surface perturbation is through Fourier analysis which is suitable for large-scale sinusoidal structures and is straightforward mathematically. In surfaces of practical interest, however, to a wide range of application, there may also be a broad spectrum of high frequency modes in addition to the lower frequency modes described by Fourier methods. We propose here that these high frequency modes can be efficiently quantified in terms of wavelet analysis. From a numerical point of view, the scale that the roughness occurs at is far to small to numerically resolve and thus we propose that our new methodology can be used to model the subgrid scale generation of vorticity. Thus the combination of wavelet analysis and Fourier analysis will be used to model the generation of vorticity for the RM instability.

  8. Hilbert Statistics of Vorticity Scaling in Two-Dimensional Turbulence

    CERN Document Server

    Tan, H S; Meng, Jianping

    2014-01-01

    In this paper, the scaling property of the inverse energy cascade and forward enstrophy cascade of the vorticity filed $\\omega(x,y)$ in two-dimensional (2D) turbulence is analyzed. This is accomplished by applying a Hilbert-based technique, namely Hilbert-Huang Transform, to a vorticity field obtained from a $8192^2$ grid-points direct numerical simulation of the 2D turbulence with a forcing scale $k_f=100$ and an Ekman friction. The measured joint probability density function $p(C,k)$ of mode $C_i(x)$ of the vorticity $\\omega$ and instantaneous wavenumber $k(x)$ is separated by the forcing scale $k_f$ into two parts, which corresponding to the inverse energy cascade and the forward enstrophy cascade. It is found that all conditional pdf $p(C\\vert k)$ at given wavenumber $k$ has an exponential tail. In the inverse energy cascade, the shape of $p(C\\vert k)$ does collapse with each other, indicating a nonintermittent cascade. The measured scaling exponent $\\zeta_{\\omega}^I(q)$ is linear with the statistical ord...

  9. Factors associated with left ventricular hypertrophy in adults with surgically repaired coarctation of the aorta

    Directory of Open Access Journals (Sweden)

    Daniel Rinnström

    2013-01-01

    Conclusion: Increased LVM is a common late finding after surgically repaired CoA. This study showed that LVM was associated with modifiable factors; systolic blood pressure and aortic valve disease. As most patients are young, and increased LVM will eventually affect ventricular function, close attention to blood pressure optimization may be of particular importance in the surgically repaired CoA population.

  10. Dynamics of vortices in complex wakes: Modeling, analysis, and experiments

    Science.gov (United States)

    Basu, Saikat

    The thesis develops singly-periodic mathematical models for complex laminar wakes which are formed behind vortex-shedding bluff bodies. These wake structures exhibit a variety of patterns as the bodies oscillate or are in close proximity of one another. The most well-known formation comprises two counter-rotating vortices in each shedding cycle and is popularly known as the von Karman vortex street. Of the more complex configurations, as a specific example, this thesis investigates one of the most commonly occurring wake arrangements, which consists of two pairs of vortices in each shedding period. The paired vortices are, in general, counter-rotating and belong to a more general definition of the 2P mode, which involves periodic release of four vortices into the flow. The 2P arrangement can, primarily, be sub-classed into two types: one with a symmetric orientation of the two vortex pairs about the streamwise direction in a periodic domain and the other in which the two vortex pairs per period are placed in a staggered geometry about the wake centerline. The thesis explores the governing dynamics of such wakes and characterizes the corresponding relative vortex motion. In general, for both the symmetric as well as the staggered four vortex periodic arrangements, the thesis develops two-dimensional potential flow models (consisting of an integrable Hamiltonian system of point vortices) that consider spatially periodic arrays of four vortices with their strengths being +/-Gamma1 and +/-Gamma2. Vortex formations observed in the experiments inspire the assumed spatial symmetry. The models demonstrate a number of dynamic modes that are classified using a bifurcation analysis of the phase space topology, consisting of level curves of the Hamiltonian. Despite the vortex strengths in each pair being unequal in magnitude, some initial conditions lead to relative equilibrium when the vortex configuration moves with invariant size and shape. The scaled comparisons of the

  11. Valproic Acid as a Cause of Transient Atrio-Ventricular Conduction Block Episodes.

    Science.gov (United States)

    Davutoglu, Vedat; Neyal, Munife; Altunbas, Gokhan

    2017-01-01

    Herein we share, to our knowledge for the first time, a a case of valproic acid use complicated by symptomatic atrio-ventricular conduction block episodes on Holter monitoring. Symptomatic atrio-ventricular block episodes should be considered as an unusual side effect of valproic acid despite normal blood therapeutic level. Before consideration of pacemaker implantation in such cases, valproic acid usage should be investigated, and dose reduction should be attempted.

  12. The influence of real-time blood glucose levels on left ventricular myocardial strain and strain rate in pediatric patients with type 1 diabetes mellitus - a speckle tracking echocardiography study

    OpenAIRE

    Hensel, Kai O.; Grimmer, Franziska; Jenke, Andreas C.; Wirth, Stefan; Heusch, Andreas

    2015-01-01

    Background Echocardiographic myocardial performance parameters such as strain and strain rate are increasingly used to assess systolic and diastolic function in patients with diabetes mellitus and several other clinical and scientific scenarios. While long-term metabolic marks such as HbA1C are inherently assessed in diabetic patients, the actual blood glucose level at the very moment of the echocardiographic study has not yet been taken into account for the assessment of cardiac mechanics. T...

  13. Ventricular arrhythmias and left ventricular hypertrophy in hypertrophic cardiomyopathy.

    Science.gov (United States)

    Piva e Mattos, Beatriz; Torres, Marco Antonio Rodrigues; Freitas, Valéria Centeno de; Scolari, Fernando Luís; Loreto, Melina Silva de

    2013-05-01

    In hypertrophic cardiomyopathy (HCM), the degree of left ventricular hypertrophy (LVH) could influence the development of ventricular arrhythmias. In HCM, analyze the association between the occurrence of ventricular arrhythmias determined by Holter electrocardiogram (ECG-Holter) and the degree of LVH determined by maximum wall thickness (MWT) in echocardiography and body mass index (BMI). Fifty-four consecutive patients with HCM underwent 24-hour ECG-Holter and echocardiography for assessment of level of LVH through MWT and BMI. Two levels were established for the occurrence of Ventricular Arrhythmias: I - alone or paired extrasystoles and II - Non- Sustained Ventricular Tachycardia (NSVT). In 13 patients (24%) with NSVT (level II), there was a higher frequency of MWT of the left ventricle (LV) > 21 mm (n = 10, 77%, 25 ± 4 mm) and LLLV = 144 g/m² (n = 10, 77%, 200 ± 30 g/m²), in comparison with those presenting with extrasystole arrhythmias (level I) (n = 41, 76%), in which these measures were identified in, respectively, 37 % (n= 15, 23 ± 1 mm), p = 0.023, and 39% (n = 16, 192 ± 53 g / m²) of the cases (p = 0.026). The cut-off values mentioned were determined by the ROC curve with a confidence interval of 95%. NSVT was more common in patients with MWTLV > 21 mm and LLLV > 144 g/m² (8 of 13, 62%) than in those with (4 of 13, 31%) or without (1 of 13; 8%) echocardiographic variables above cut-off values (p = 0.04). In HCM, occurrence of ventricular arrhythmias by Holter was associated with the degree of LVH assessed by echocardiography through MWT and BMI.

  14. Angiographic differentiation of type of ventricular septal defects

    Energy Technology Data Exchange (ETDEWEB)

    Cheon, Mal Soon; Park, Hee Young; Kim, Yang Sook [Marynoll Hospital, Busan (Korea, Republic of)

    1989-06-15

    Defects of the ventricular septum are the commonest type of congenital cardiac malformations. A classification with axial angiography of the subtypes of ventricular septal defects is proposed on the study of 126 patients with defects of the ventricular septum. The results were as follows: 1. The incidence of the ventricular septal defects was 39.6% of congenital heart malformation. 2. The sex distribution of cases were 70 males and 56 females, the age ranged from 13 months to 26 years. 3. Angiographic features seen by axial angiography were as follows: a. Perimembranous defects as seen on long axial view of left ventriculogram were in continuity wity aortic valve. The relation of the defect to the tricuspid valve allows distinction of the extension of the preimembranous defect toward inlet, trabecular, or infundibular zones. This relation was determined angiographically, using the course of the contrast medium from the left ventricle through the ventricular septal defect, opacifying the right ventricle. In inlet excavation, the shunted blood opacified the recess between septal leaflet of tricuspid valve and interventricular septum in early phase, in infundibular excavation, opacified the recess between anterior leaflet of tricuspid valve and anterior free wall of right ventricle and in trabecular excavation, the shunted blood traversed anterior portion of tricuspid valve ring, opacified trabecular portion of right ventricle. b. Muscular defects were separated from the semilunar and atrioventricular valves. c, Subarterial defects were related to both semilunar valves, and they were best demonstrated on the elongated right anterior oblique view of the left ventriculogram. d. Total infundibular defects were profiled in right anterior oblique 30 and long axial view, subaortic in location in both views.

  15. Galen and the ventricular system.

    Science.gov (United States)

    Rocca, J

    1997-12-01

    This paper examines the anatomy and physiology, together with the pathophysiology, of the ventricular system of the brain, as it was understood by arguably its greatest exponent in Western Antiquity, Galen. According to him, the purpose of the ventricles was to elaborate, store and distribute psychic pneuma, the motive force of Galenic neurology, throughout the nervous system. However, impressive as the delineation of the ventricular system is, the details of this distribution are not forthcoming from Galen. Finally, I discuss the ventricles as the site of intellect, a notion only tentatively advanced by Galen, but cast into dogma by his successors. For all the mistakes Galen made in anatomy and physiology, the study of the ventricular system reveals a mind not dissimilar to our own.

  16. Sharp asymptotic estimates for vorticity solutions of the 2D Navier-Stokes equation

    Directory of Open Access Journals (Sweden)

    Yuncheng You

    2008-12-01

    Full Text Available The asymptotic dynamics of high-order temporal-spatial derivatives of the two-dimensional vorticity and velocity of an incompressible, viscous fluid flow in $mathbb{R}^2$ are studied, which is equivalent to the 2D Navier-Stokes equation. It is known that for any integrable initial vorticity, the 2D vorticity solution converges to the Oseen vortex. In this paper, sharp exterior decay estimates of the temporal-spatial derivatives of the vorticity solution are established. These estimates are then used and combined with similarity and $L^p$ compactness to show the asymptotical attraction rates of temporal-spatial derivatives of generic 2D vorticity and velocity solutions by the Oseen vortices and velocity solutions respectively. The asymptotic estimates and the asymptotic attraction rates of all the derivatives obtained in this paper are independent of low or high Reynolds numbers.

  17. Clinical use of ultrashort-lived radionuclide krypton-81m for noninvasive analysis of right ventricular performance in normal subjects and patients with right ventricular dysfunction

    Energy Technology Data Exchange (ETDEWEB)

    Nienaber, C.A.; Spielmann, R.P.; Wasmus, G.; Mathey, D.G.; Montz, R.; Bleifeld, W.H.

    1985-03-01

    The ultrashort-lived radionuclide krypton-81m, eluted in 5% dextrose from a bedside rubidium-81m generator, was intravenously infused for rapid imaging of the right-sided heart chambers in the right anterior oblique projection adjusted for optimal right atrioventricular separation. Left-sided heart and lung background was minimized by rapid decay and efficient exhalation of krypton-81m, requiring no algorithm for background correction. A double region of interest method decreased the variability in the assessment of ejection fraction to 5%. In 10 normal subjects, 11 patients with pulmonary hypertension, 4 patients with right ventricular outflow tract obstruction and 4 patients with right ventricular infarction, right ventricular ejection fraction determined by krypton-81m equilibrium blood pool imaging ranged from 14 to 76%. The correlation between these values and those determined by cineangiography according to Simpson's rule was close: r . 0.93 for all data points, r . 0.92 for studies at rest and r . 0.93 for exercise studies. Exercise-related changes in right ventricular function revealed a disturbed functional reserve with pulmonary hypertension and right ventricular infarction, whereas in compensated right ventricular outflow tract obstruction there was a physiologic increase in ejection fraction with exercise. Thus, equilibrium-gated right ventricular imaging using ultrashort-lived krypton-81m is a simple, accurate and reproducible method with potential for serial assessment of right ventricular ejection fraction in a variety of right ventricular anatomic and functional abnormalities, both at rest and during exercise. Advantages of this method include an extremely low radiation dose to patients and clear right atrioventricular separation without the need to correct for background activity.

  18. Details of left ventricular radial wall motion supporting the ventricular theory of the third heart sound obtained by cardiac MR.

    Science.gov (United States)

    Codreanu, I; Robson, M D; Rider, O J; Pegg, T J; Dasanu, C A; Jung, B A; Rotaru, N; Clarke, K; Holloway, C J

    2014-05-01

    Obtaining new details of radial motion of left ventricular (LV) segments using velocity-encoding cardiac MRI. Cardiac MR examinations were performed on 14 healthy volunteers aged between 19 and 26 years. Cine images for navigator-gated phase contrast velocity mapping were acquired using a black blood segmented κ-space spoiled gradient echo sequence with a temporal resolution of 13.8 ms. Peak systolic and diastolic radial velocities as well as radial velocity curves were obtained for 16 ventricular segments. Significant differences among peak radial velocities of basal and mid-ventricular segments have been recorded. Particular patterns of segmental radial velocity curves were also noted. An additional wave of outward radial movement during the phase of rapid ventricular filling, corresponding to the expected timing of the third heart sound, appeared of particular interest. The technique has allowed visualization of new details of LV radial wall motion. In particular, higher peak systolic radial velocities of anterior and inferior segments are suggestive of a relatively higher dynamics of anteroposterior vs lateral radial motion in systole. Specific patterns of radial motion of other LV segments may provide additional insights into LV mechanics. The outward radial movement of LV segments impacted by the blood flow during rapid ventricular filling provides a potential substrate for the third heart sound. A biphasic radial expansion of the basal anteroseptal segment in early diastole is likely to be related to the simultaneous longitudinal LV displacement by the stretched great vessels following repolarization and their close apposition to this segment.

  19. Genetics Home Reference: arrhythmogenic right ventricular cardiomyopathy

    Science.gov (United States)

    ... Twitter Home Health Conditions ARVC Arrhythmogenic right ventricular cardiomyopathy Printable PDF Open All Close All Enable Javascript ... the expand/collapse boxes. Description Arrhythmogenic right ventricular cardiomyopathy ( ARVC ) is a form of heart disease that ...

  20. Comparison between tagged MRI and standard cine MRI for evaluation of left ventricular ejection fraction

    Energy Technology Data Exchange (ETDEWEB)

    Dornier, Christophe; Ivancevic, Marko K.; Didier, Dominique; Vallee, Jean-Paul [Departement de Radiologie et d' Informatique Medicale, Hopitaux Universitaires de Geneve, 24 rue Micheli-du-Crest, 1211, Geneva (Switzerland); Somsen, G. Aernout; Righetti, Alberto [Div. de Cardiologie, Departement de Medecine Interne, Hopitaux Universitaires de Geneve, 24 rue Micheli-du-Crest, 1211, Geneva (Switzerland); Osman, Nael F. [Department of Radiology, Johns Hopkins University, 600 North Wolfe Street, 21287, Baltimore, MD (United States)

    2004-08-01

    Global left ventricular function is a prognostic indicator and is used to evaluate therapeutical interventions in patients with heart failure. Regional left ventricular function can be determined with tagged MRI. Assessment of global left ventricular function using the tagging data may have additional clinical value without incurring extra scanning time, which is currently a limiting factor in cardiac imaging. Direct determination of end-diastolic volume is not possible with conventional tagged MRI. However, end-systolic volume can be directly measured because myocardium-blood contrast improves through a tagged image series. We investigated the potential of tagged MRI using frequency-domain analysis software to retrospectively track end-diastolic contour from end-systolic contour and subsequently calculate the ejection fraction. Tagged MRI was compared with the standard bright-blood cine MRI in healthy volunteers (n=20) and patients with previous myocardial infarction (n=8). Left ventricular ejection fraction derived from tagged MRI is linearly correlated to left ventricular ejection fraction obtained by standard cardiac cine MRI (y=1.0x+1.31, r>0.98, p=0.014). In addition, the inter-observer and intra-observer coefficient of variation for left ventricular ejection fraction measurements was low (CV{sub intra}=0.4%, CV{sub inter}=1.3%). With tagged MRI, only end-systolic volume needs to be manually determined, and accurate estimation of left ventricular ejection fraction is obtained because end-diastolic and end-systolic volumes are determined using identical anatomical points. Our data indicate that tagged MRI can be used to quantitatively assess both regional and global left ventricular function. Therefore, tagged MRI may be a valuable clinical tool for determining the prognosis and evaluating the effect of therapeutical intervention using a single imaging session in patients with left ventricular dysfunction. (orig.)

  1. Local and Nonlocal Strain Rate Fields and Vorticity Alignment in Turbulent Flows

    OpenAIRE

    Hamlington, Peter E.; Schumacher, Jörg; Dahm, Werner J. A.

    2008-01-01

    Local and nonlocal contributions to the total strain rate tensor at any point in a flow are formulated from an expansion of the vorticity field in a local spherical neighborhood of radius R centered on x. The resulting exact expression allows the nonlocal (background) strain rate tensor to be obtained from the total strain rate tensor. In turbulent flows, where the vorticity naturally concentrates into relatively compact structures, this allows the local alignment of vorticity with the most e...

  2. Velocity-vorticity formulation of three-dimensional, steady, viscous, incompressible flows

    Energy Technology Data Exchange (ETDEWEB)

    Meir, A.J. [Auburn Univ., AL (United States)

    1994-12-31

    In this work we discuss some aspects of the velocity-vorticity formulation of three-dimensional, steady, viscous, incompressible flows. We describe reasonable boundary conditions that should be imposed on the vorticity and a compatibility condition that the vorticity must satisfy. This formulation may give rise to efficient numerical algorithms for approximating solutions of the Stokes problem, which in turn yields an iterative method for approximating solutions of the Navier-Stokes equations.

  3. Topological Interactions of Non-Abelian Vortices with Quasi-Particles in High Density QCD

    OpenAIRE

    Hirono, Yuji; Kanazawa, Takuya; Nitta, Muneto

    2010-01-01

    Non-Abelian vortices are topologically stable objects in the color-flavor locked (CFL) phase of dense QCD. We derive a dual Lagrangian starting with the Ginzburg-Landau effective Lagrangian for the CFL phase, and obtain topological interactions of non-Abelian vortices with quasiparticles such as $U(1)_B$ Nambu-Goldstone bosons (phonons) and massive gluons. We find that the phonons couple to the translational zero modes of the vortices while the gluons couple to their orientational zero modes ...

  4. Time-resolved photoemission electron microscopy imaging of mode coupling between three interacting magnetic vortices

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao; Cheng, X. M., E-mail: xcheng@brynmawr.edu [Department of Physics, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010 (United States); Keavney, D. J. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Asmat-Uceda, M.; Buchanan, K. S. [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States); Melikyan, A. [American Physical Society, Ridge, New York 11961 (United States)

    2014-09-08

    The interactions between three magnetic vortices in a planar equilateral triangular arrangement were studied by time-resolved photoemission electron microscopy. The gyrotropic resonance frequencies of the three individual vortices in the tri-disk system are different from one another and also shifted from that of an isolated vortex by as much as 12%. A comparison with analytical calculations and numerical simulations shows that the observed frequency shifts result from the dipolar interaction between the vortices.

  5. Quantized vortices in arbitrary dimensions and the normal-to-superfluid phase transition

    Science.gov (United States)

    Bora, Florin

    The structure and energetics of superflow around quantized vortices, and the motion inherited by these vortices from this superflow, are explored in the general setting of a superfluid in arbitrary dimensions. The vortices may be idealized as objects of co-dimension two, such as one-dimensional loops and two-dimensional closed surfaces, respectively, in the cases of three- and four-dimensional superfluidity. By using the analogy between vortical superflow and Ampere-Maxwell magnetostatics, the equilibrium superflow containing any specified collection of vortices is constructed. The energy of the superflow is found to take on a simple form for vortices that are smooth and asymptotically large, compared with the vortex core size. The motion of vortices is analyzed in general, as well as for the special cases of hyper-spherical and weakly distorted hyper-planar vortices. In all dimensions, vortex motion reflects vortex geometry. In dimension four and higher, this includes not only extrinsic but also intrinsic aspects of the vortex shape, which enter via the first and second fundamental forms of classical geometry. For hyper-spherical vortices, which generalize the vortex rings of three dimensional superfluidity, the energy-momentum relation is determined. Simple scaling arguments recover the essential features of these results, up to numerical and logarithmic factors. Extending these results to systems containing multiple vortices is elementary due to the linearity of the theory. The energy for multiple vortices is thus a sum of self-energies and power-law interaction terms. The statistical mechanics of a system containing vortices is addressed via the grand canonical partition function. A renormalization-group analysis in which the low energy excitations are integrated approximately, is used to compute certain critical coefficients. The exponents obtained via this approximate procedure are compared with values obtained previously by other means. For dimensions higher

  6. Vortex identification from local properties of the vorticity field

    Science.gov (United States)

    Elsas, J. H.; Moriconi, L.

    2017-01-01

    A number of systematic procedures for the identification of vortices/coherent structures have been developed as a way to address their possible kinematical and dynamical roles in structural formulations of turbulence. It has been broadly acknowledged, however, that vortex detection algorithms, usually based on linear-algebraic properties of the velocity gradient tensor, can be plagued with severe shortcomings and may become, in practical terms, dependent on the choice of subjective threshold parameters in their implementations. In two-dimensions, a large class of standard vortex identification prescriptions turn out to be equivalent to the "swirling strength criterion" (λc i-criterion), which is critically revisited in this work. We classify the instances where the accuracy of the λc i-criterion is affected by nonlinear superposition effects and propose an alternative vortex detection scheme based on the local curvature properties of the vorticity graph (x ,y ,ω ) —the "vorticity curvature criterion" (λω-criterion)—which improves over the results obtained with the λc i-criterion in controlled Monte Carlo tests. A particularly problematic issue, given its importance in wall-bounded flows, is the eventual inadequacy of the λc i-criterion for many-vortex configurations in the presence of strong background shear. We show that the λω-criterion is able to cope with these cases as well, if a subtraction of the mean velocity field background is performed, in the spirit of the Reynolds decomposition procedure. A realistic comparative study for vortex identification is then carried out for a direct numerical simulation of a turbulent channel flow, including a three-dimensional extension of the λω-criterion. In contrast to the λc i-criterion, the λω-criterion indicates in a consistent way the existence of small scale isotropic turbulent fluctuations in the logarithmic layer, in consonance with long-standing assumptions commonly taken in turbulent boundary

  7. Topology of streamlines and vorticity contours for two - dimensional flows

    DEFF Research Database (Denmark)

    Andersen, Morten

    Considering a coordinate-free formulation of helical symmetry rather than more traditional definitions based on coordinates, we discuss basic properties of helical vector fields and compare results from the literature. For inviscid flow where a velocity field is generated by a sum of helical vortex...... the singularities are treated as centers. The last topology is a single center which is consistent with the powerful result on the long time behaviour proved by Gallay & Wayne (Comm. in Math. Phys. 255, 2005). The case of three critical points of the streamlines is a subset of three critical points of the vorticity...

  8. Nonlinear modes in the hollow-cores of liquid vortices

    KAUST Repository

    Amaouche, Mustapha

    2013-09-01

    In this paper we show that the wave patterns observed on the interfacial contours of hollow-core vortices, produced within a shallow layer of fluid contained in stationary cylinder and driven by a rotating disk at the bottom [G.H. Vatistas, H.A. Abderrahmane, M.H. Kamran Siddiqui, Experimental confirmation of Kelvin\\'s equilibria, Phys. Rev. Lett. 100 (2008) 174503-174504], can be described as travelling cnoidal waves. These rotating stationary waves are obtained as solutions of a Korteweg-de Vries type equation, in accordance with the geometrical and kinematic characteristics of the observed polygonal patterns. © 2013 Elsevier Masson SAS. All rights reserved.

  9. How hairpin vortices emerge from exact invariant solutions

    Science.gov (United States)

    Schneider, Tobias M.; Farano, Mirko; de Palma, Pietro; Robinet, Jean-Christoph; Cherubini, Stefania

    2017-11-01

    Hairpin vortices are among the most commonly observed flow structures in wall-bounded shear flows. However, within the dynamical system approach to turbulence, those structures have not yet been described. They are not captured by known exact invariant solutions of the Navier-Stokes equations nor have other state-space structures supporting hairpins been identified. We show that hairpin structures are observed along an optimally growing trajectory leaving a well known exact traveling wave solution of plane Poiseuille flow. The perturbation triggering hairpins does not correspond to an unstable mode of the exact traveling wave but lies in the stable manifold where non-normality causes strong transient amplification.

  10. Spins in the vortices of a high-temperature superconductor

    DEFF Research Database (Denmark)

    Lake, B.; Aeppli, G.; Clausen, K.N.

    2001-01-01

    Neutron scattering is used to characterize the magnetism of the vortices for the optimally doped high-temperature superconductor La2-xSrxCuO4 (x = 0.163) in an applied magnetic field. As temperature is reduced, Low-frequency spin fluctuations first disappear with the loss of vortex mobility......, but then reappear. We find that the vortex state can be regarded as an inhomogeneous mixture of a superconducting spin fluid and a material containing a nearly ordered antiferromagnet. These experiments show that as for many other properties of cuprate superconductors, the important underlying microscopic forces...

  11. A turbulence model for buoyant flows based on vorticity generation.

    Energy Technology Data Exchange (ETDEWEB)

    Domino, Stefan Paul; Nicolette, Vernon F.; O' Hern, Timothy John; Tieszen, Sheldon R.; Black, Amalia Rebecca

    2005-10-01

    A turbulence model for buoyant flows has been developed in the context of a k-{var_epsilon} turbulence modeling approach. A production term is added to the turbulent kinetic energy equation based on dimensional reasoning using an appropriate time scale for buoyancy-induced turbulence taken from the vorticity conservation equation. The resulting turbulence model is calibrated against far field helium-air spread rate data, and validated with near source, strongly buoyant helium plume data sets. This model is more numerically stable and gives better predictions over a much broader range of mesh densities than the standard k-{var_epsilon} model for these strongly buoyant flows.

  12. The numerical solution of the vorticity transport equation

    CERN Document Server

    Dennis, S C R

    1973-01-01

    A method of approximating the two-dimensional vorticity transport equation in which the matrix associated with the difference equations is diagonally dominant and the truncation error is the same as that of the fully central-difference approximation, is discussed. An example from boundary layer theory is given by calculating the viscous stagnation point flow at the nose of a cylinder. Some new solutions of the Navier-Stokes equations are obtained for symmetrical flow past a flat plate of finite length. (16 refs).

  13. The influence of trailed vorticity on flutter speed estimations

    DEFF Research Database (Denmark)

    Pirrung, Georg; Aagaard Madsen, Helge; Kim, Taeseong

    2014-01-01

    ) theory, which is coupled with Beddoes' near wake model for trailed vorticity. The first part of this work outlines the implementation in HAWC2, with a focus on the interaction of the induction from the blade based near wake model with the induction from the polar grid based BEM model in HAWC2...... building up at a critical rotor speed. Blades with modified torsional and flapwise stiffness are also investigated. A flutter analysis is often part of the stability investigations for new blades but is normally carried out with engineering models that do not include the influence of unsteady trailed...

  14. Topological charge algebra of optical vortices in nonlinear interactions.

    Science.gov (United States)

    Zhdanova, Alexandra A; Shutova, Mariia; Bahari, Aysan; Zhi, Miaochan; Sokolov, Alexei V

    2015-12-28

    We investigate the transfer of orbital angular momentum among multiple beams involved in a coherent Raman interaction. We use a liquid crystal light modulator to shape pump and Stokes beams into optical vortices with various integer values of topological charge, and cross them in a Raman-active crystal to produce multiple Stokes and anti-Stokes sidebands. We measure the resultant vortex charges using a tilted-lens technique. We verify that in every case the generated beams' topological charges obey a simple relationship, resulting from angular momentum conservation for created and annihilated photons, or equivalently, from phase-matching considerations for multiple interacting beams.

  15. Close pairs of relative equilibria for identical point vortices

    DEFF Research Database (Denmark)

    Dirksen, Tobias; Aref, Hassan

    2011-01-01

    Numerical solution of the classical problem of relative equilibria for identical point vortices on the unbounded plane reveals configurations that are very close to the analytically known, centered, symmetrically arranged, nested equilateral triangles. New numerical solutions of this kind are found...... also has this property, and new relative equilibria close to the nested, symmetrically arranged, regular heptagons have been found. The centered regular nonagon is also marginally stable. Again, a new family of close relative equilibria has been found. The closest relative equilibrium pairs occur...

  16. Non-Abelian statistics of vortices with non-Abelian Dirac fermions.

    Science.gov (United States)

    Yasui, Shigehiro; Hirono, Yuji; Itakura, Kazunori; Nitta, Muneto

    2013-05-01

    We extend our previous analysis on the exchange statistics of vortices having a single Dirac fermion trapped in each core to the case where vortices trap two Dirac fermions with U(2) symmetry. Such a system of vortices with non-Abelian Dirac fermions appears in color superconductors at extremely high densities and in supersymmetric QCD. We show that the exchange of two vortices having doublet Dirac fermions in each core is expressed by non-Abelian representations of a braid group, which is explicitly verified in the matrix representation of the exchange operators when the number of vortices is up to four. We find that the result contains the matrices previously obtained for the vortices with a single Dirac fermion in each core as a special case. The whole braid group does not immediately imply non-Abelian statistics of identical particles because it also contains exchanges between vortices with different numbers of Dirac fermions. However, we find that it does contain, as its subgroup, genuine non-Abelian statistics for the exchange of the identical particles, that is, vortices with the same number of Dirac fermions. This result is surprising compared with conventional understanding because all Dirac fermions are defined locally at each vortex, unlike the case of Majorana fermions for which Dirac fermions are defined nonlocally by Majorana fermions located at two spatially separated vortices.

  17. Acoustic Virtual Vortices with Tunable Orbital Angular Momentum for Trapping of Mie Particles

    Science.gov (United States)

    Marzo, Asier; Caleap, Mihai; Drinkwater, Bruce W.

    2018-01-01

    Acoustic vortices can transfer angular momentum and trap particles. Here, we show that particles trapped in airborne acoustic vortices orbit at high speeds, leading to dynamic instability and ejection. We demonstrate stable trapping inside acoustic vortices by generating sequences of short-pulsed vortices of equal helicity but opposite chirality. This produces a "virtual vortex" with an orbital angular momentum that can be tuned independently of the trapping force. We use this method to adjust the rotational speed of particles inside a vortex beam and, for the first time, create three-dimensional acoustics traps for particles of wavelength order (i.e., Mie particles).

  18. Prescribed Velocity Gradients for Highly Viscous SPH Fluids with Vorticity Diffusion.

    Science.gov (United States)

    Peer, Andreas; Teschner, Matthias

    2017-12-01

    Working with prescribed velocity gradients is a promising approach to efficiently and robustly simulate highly viscous SPH fluids. Such approaches allow to explicitly and independently process shear rate, spin, and expansion rate. This can be used to, e.g., avoid interferences between pressure and viscosity solvers. Another interesting aspect is the possibility to explicitly process the vorticity, e.g., to preserve the vorticity. In this context, this paper proposes a novel variant of the prescribed-gradient idea that handles vorticity in a physically motivated way. In contrast to a less appropriate vorticity preservation that has been used in a previous approach, vorticity is diffused. The paper illustrates the utility of the vorticity diffusion. Therefore, comparisons of the proposed vorticity diffusion with vorticity preservation and additionally with vorticity damping are presented. The paper further discusses the relation between prescribed velocity gradients and prescribed velocity Laplacians which improves the intuition behind the prescribed-gradient method for highly viscous SPH fluids. Finally, the paper discusses the relation of the proposed method to a physically correct implicit viscosity formulation.

  19. Quantized vortices and superflow in arbitrary dimensions: structure, energetics and dynamics

    Science.gov (United States)

    Goldbart, Paul M.; Bora, Florin

    2009-05-01

    The structure and energetics of superflow around quantized vortices, and the motion inherited by these vortices from this superflow, are explored in the general setting of a superfluid in arbitrary dimensions. The vortices may be idealized as objects of codimension 2, such as one-dimensional loops and two-dimensional closed surfaces, respectively, in the cases of three- and four-dimensional superfluidity. By using the analogy between the vortical superflow and Ampère-Maxwell magnetostatics, the equilibrium superflow containing any specified collection of vortices is constructed. The energy of the superflow is found to take on a simple form for vortices that are smooth and asymptotically large, compared with the vortex core size. The motion of vortices is analyzed in general, as well as for the special cases of hyper-spherical and weakly distorted hyper-planar vortices. In all dimensions, vortex motion reflects vortex geometry. In dimension 4 and higher, this includes not only extrinsic but also intrinsic aspects of the vortex shape, which enter via the first and second fundamental forms of classical geometry. For hyper-spherical vortices, which generalize the vortex rings of three-dimensional superfluidity, the energy-momentum relation is determined. Simple scaling arguments recover the essential features of these results, up to numerical and logarithmic factors.

  20. The effect of noise and sampling size on vorticity measurements in rotating fluids

    Science.gov (United States)

    Wong, Kelvin K. L.; Kelso, Richard M.; Mazumdar, Jagannath; Abbott, Derek

    2008-11-01

    This paper describes a new technique for presenting information based on given flow images. Using a multistep first order differentiation technique, we are able to map in two dimensions, vorticity of fluid within a region of investigation. We can then present the distribution of this property in space by means of a color intensity map. In particular, the state of fluid rotation can be displayed using maps of vorticity flow values. The framework that is implemented can also be used to quantify the vortices using statistical properties which can be derived from such vorticity flow maps. To test our methodology, we have devised artificial vortical flow fields using an analytical formulation of a single vortex. Reliability of vorticity measurement from our results shows that the size of flow vector sampling and noise in flow field affect the generation of vorticity maps. Based on histograms of these maps, we are able to establish an optimised configuration that computes vorticity fields to approximate the ideal vortex statistically. The novel concept outlined in this study can be used to reduce fluctuations of noise in a vorticity calculation based on imperfect flow information without excessive loss of its features, and thereby improves the effectiveness of flow

  1. Prevalence and correlates of echocardiographic determined left ventricular hypertrophy in 2318 asymptomatic middle-aged men: the ECCIS project. Epidemiolgia e Clinica della Cardiopatia Ischemica Silente.

    Science.gov (United States)

    Antoniucci, D; Seccareccia, F; Menotti, A; Dovellini, E V; Prati, P L; Rovelli, F; Fazzini, P F

    1997-04-01

    It is well established that left ventricular hypertrophy is a strong and independent risk factor for cardiovascular morbidity and mortality. This study was designed to determine the prevalence and correlates of left ventricular hypertrophy (LVH) among a sample population of 2318 totally asymptomatic men aged 40-59. This sample is a subset of the participants in the ECCIS Project. Left ventricular mass was estimated by echocardiography. The following individual variables were employed in the multiple linear regression analyses: age, diastolic and systolic blood pressure at rest and at peak exercise, body mass index, body surface area, conditioning physical activity. Three indexes of left ventricular mass were used: left ventricular mass/height, left ventricular mass/body surface area and "adjusted left ventricular mass" derived from adjustment, using a regression model, of left ventricular mass by age, body mass index and body surface area. The sample was subdivided in 3 blood pressure classes; normotensive (n = 1605), borderline (n = 390) and hypertensive (n = 323). All the variables considered with the exception of diastolic blood pressure both at rest and peak exercise were significantly correlated with left ventricular mass. Upper normal limits for left ventricular mass indexed to height and body surface area and of adjusted left ventricular mass were 143 g/m, 129 g/m2, and 245 g respectively. The prevalences of left ventricular hypertrophy, as determined by the reference standard of left ventricular mass/height, left.ventricular mass/body surface area and adjusted left ventricular mass, ranged 2.7-3.2% in the normotensive group, 4.2-5.4% in the borderline group and 11.8-14.5% in the hypertensive group, and were lower using adjusted left ventricular mass index. The results of this study show that the prevalence of left ventricular hypertrophy using adjustment by age, body surface area and body mass index reduces variability of left ventricular mass associated

  2. Shallow water modeling of Jovian polar cyclone and vortices

    Science.gov (United States)

    Li, Cheng; Tabataba-Vakili, Fachreddin; Ingersoll, Andrew P.

    2017-10-01

    Jupiter’s polar atmosphere was observed for the first time by the Juno visible spectrum camera (JunoCAM) and Juno Infrared Auroral Mapper (JIRAM). Both the visible and infrared images show active vortices and weather systems that are unlike any polar regions previously seen or modeled on any of the planets in our solar system. We developed a global shallow water model on a sphere with poles rotated to the equator to investigate the formation, maintenance and dynamic regimes controlling the morphology of polar cyclones and vortices. Passive Lagrangian particles with finite life time are included to represent the clouds. We verified that a westward barotropically unstable jet can spontaneously break the axial symmetry into a polygon-shaped figure rotating rigidly around the rotation axis as reported by previous laboratory experiments. The number of sides of the polygon depends on the deformation radius and is insensitive to the initial condition. Why Jupiter’s pole is different from Saturn’s is still under investigation.

  3. Geometric phase mediated topological transport of sound vortices

    CERN Document Server

    Wang, Shubo; Chan, C T

    2016-01-01

    When a physical system undergoes a cyclic evolution, a non-integrable phase can arise in addition to the normal dynamical phase. This phase, depending only on the geometry of the path traversed in the parameter space and hence named geometric phase, has profound impact in both classical and quantum physics, leading to exotic phenomena such as electron weak anti-localization and light spin-Hall effect. Experimental observations of the geometric phase effect in classical system are typically realized using vector waves such as light characterized by a polarization. We show here that such an effect can also be realized in scalar wave systems such as sound wave. Using a helical hollow waveguide, we show that the geometric phase effect associated with the transportation of sound vortices, i.e. sound wave carrying intrinsic orbital angular momentum, can serve as a potential mechanism to control the flow of sound vortices with different topological charges, resulting in geometric phase-based sound vortex filters.

  4. Classification of hemispheric monthly mean stratospheric potential vorticity fields

    Directory of Open Access Journals (Sweden)

    R. Huth

    2003-03-01

    Full Text Available Monthly mean NCEP reanalysis potential vorticity fields at the 650 K isentropic level over the Northern and Southern Hemispheres between 1979 and 1997 were studied using multivariate analysis tools. Principal component analysis in the T-mode was applied to demonstrate the validity of such statistical techniques for the study of stratospheric dynamics and climatology. The method, complementarily applied to both the raw and anomaly fields, was useful in determining and classifying the characteristics of winter and summer PV fields on both hemispheres, in particular, the well-known differences in the behaviour and persistence of the polar vortices. It was possible to identify such features as sudden warming events in the Northern Hemisphere and final warming dates in both hemispheres. The stratospheric impact of other atmospheric processes, such as volcanic eruptions, also identified though the results, must be viewed at this stage as tentative. An interesting change in behaviour around 1990 was detected over both hemispheres.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; general circulation; climatology

  5. Classification of hemispheric monthly mean stratospheric potential vorticity fields

    Directory of Open Access Journals (Sweden)

    R. Huth

    Full Text Available Monthly mean NCEP reanalysis potential vorticity fields at the 650 K isentropic level over the Northern and Southern Hemispheres between 1979 and 1997 were studied using multivariate analysis tools. Principal component analysis in the T-mode was applied to demonstrate the validity of such statistical techniques for the study of stratospheric dynamics and climatology. The method, complementarily applied to both the raw and anomaly fields, was useful in determining and classifying the characteristics of winter and summer PV fields on both hemispheres, in particular, the well-known differences in the behaviour and persistence of the polar vortices. It was possible to identify such features as sudden warming events in the Northern Hemisphere and final warming dates in both hemispheres. The stratospheric impact of other atmospheric processes, such as volcanic eruptions, also identified though the results, must be viewed at this stage as tentative. An interesting change in behaviour around 1990 was detected over both hemispheres.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; general circulation; climatology

  6. EFT for Vortices with Dilaton-dependent Localized Flux

    CERN Document Server

    Burgess, C P; Williams, M

    2015-01-01

    We study how codimension-two objects like vortices back-react gravitationally with their environment in theories (such as 4D or higher-dimensional supergravity) where the bulk is described by a dilaton-Maxwell-Einstein system. We do so both in the full theory, for which the vortex is an explicit classical `fat brane' solution, and in the effective theory of `point branes' appropriate when the vortices are much smaller than the scales of interest for their back-reaction (such as the transverse Kaluza-Klein scale). We extend the standard Nambu-Goto description to include the physics of flux-localization wherein the ambient flux of the external Maxwell field becomes partially localized to the vortex, generalizing the results of a companion paper to include dilaton-dependence for the tension and localized flux. In the effective theory, such flux-localization is described by the next-to-leading effective interaction, and the boundary conditions to which it gives rise are known to play an important role in how (and...

  7. Bielectron vortices in two-dimensional Dirac semimetals.

    Science.gov (United States)

    Downing, C A; Portnoi, M E

    2017-10-12

    Searching for new states of matter and unusual quasi-particles in emerging materials and especially low-dimensional systems is one of the major trends in contemporary condensed matter physics. Dirac materials, which host quasi-particles which are described by ultrarelativistic Dirac-like equations, are of a significant current interest from both a fundamental and applied physics perspective. Here we show that a pair of two-dimensional massless Dirac-Weyl fermions can form a bound state independently of the sign of the inter-particle interaction potential, as long as this potential decays at large distances faster than Kepler's inverse distance law. This leads to the emergence of a new type of energetically favorable quasiparticle: bielectron vortices, which are double-charged and reside at zero-energy. Their bosonic nature allows for condensation and may give rise to Majorana physics without invoking a superconductor. These novel quasi-particles arguably explain a range of poorly understood experiments in gated graphene structures at low doping.Two-dimensional Dirac semimetals are known to host fermionic excitations which can mimic physics usually found in ultrarelativistic quantum mechanics. Here, the authors unveil the existence of another type of quasiparticle, bielectron vortices, which are bosonic and may give rise to new types of condensates.

  8. NonBoussinesq effects on vorticity and kinetic energy production

    Science.gov (United States)

    Ravichandran, S.; Dixit, Harish; Govindarajan, Rama

    2015-11-01

    The Boussinesq approximation, commonly employed in weakly compressible or incompressible flows, neglects changes in inertia due to changes in the density. However, the nonBoussinesq terms can lead to a kind of centrifugal instability for small but sharp density variations, and therefore cannot be neglected under such circumstances (see, e.g., DIXIT & GOVINDARAJAN, JFM , 2010, 415). Here, we study the evolution of a light-cored Gaussian vortex and find that the nonBoussinesq terms can lead to significant changes in how vortices evolve. The problem is governed by three nondimensional numbers--Reynolds number (i.e. viscosity), Atwood number, and a ratio of gravitational and centrifugal Froude numbers. We find that the production of kinetic energy and vorticity in a light-cored Gaussian vortex are affected significantly by the nonBoussinesq terms, and varies non-monotonically with the parameters of the problem. In general, these nonBoussinesq effects depend both on the strength of gravity and on the Reynolds number associated with the initial vortex.

  9. Generalized Hasimoto Transform, Binormal Flow and Quantized Vortices

    Science.gov (United States)

    Strong, Scott A.; Carr, Lincoln D.

    2014-03-01

    A quantized vortex is a topological object central to the study of quantum liquids. Current models of vortex dynamics are motivated by the nonlinear Schrödingier equation and porting techniques from classical vortices. Self induction of classical vorticity ideally localized to a space curve asserts that a curved vortex filament propagates at a speed proportional to its curvature, | v | ~ κ , in the binormal direction of the Frenet frame, b& circ;. Interestingly, this autonomous dynamic can be mapped into the space of solutions to a cubic focusing nonlinear Schrödinger equation, iψt +ψss +1/2| ψ | 2 ψ = 0 , where ψ is a plane-wave defined by curvature and torsion of the vortex filament, ψ = κexp [ i ∫ dsτ ] . Using these two results, one can define a vortex configuration, within superfluid helium or a Bose-Einstein condensate, and prescribe a binormal evolution. In general, however, binormal flow depends nonlinearly on local curvature and maps to a class of nonlinear integro-differential Schrödinger equations. In this talk we discuss how system size affects higher-order nonlinearity and filament geometry which is applicable to theoretical and numerical investigations of vortex dominated quantum hydrodynamics. Funded by NSF.

  10. Hemodialysis-Induced Regional Left Ventricular Systolic Dysfunction: Prevalence, Patient and Dialysis Treatment-Related Factors, and Prognostic Significance

    Science.gov (United States)

    Assa, Solmaz; Hummel, Yoran M.; Voors, Adriaan A.; Kuipers, Johanna; Westerhuis, Ralf; de Jong, Paul E.

    2012-01-01

    Summary Background and objectives The hemodialysis procedure may acutely induce regional left ventricular systolic dysfunction. This study evaluated the prevalence, time course, and associated patient- and dialysis-related factors of this entity and its association with outcome. Design, setting, participants, & measurements Hemodialysis patients (105) on a three times per week dialysis schedule were studied between March of 2009 and March of 2010. Echocardiography was performed before dialysis, at 60 and 180 minutes intradialysis, and at 30 minutes postdialysis. Hemodialysis-induced regional left ventricular systolic dysfunction was defined as an increase in wall motion score in more than or equal to two segments. Results Hemodialysis-induced regional left ventricular systolic dysfunction occurred in 29 (27%) patients; 17 patients developed regional left ventricular systolic dysfunction 60 minutes after onset of dialysis. Patients with hemodialysis-induced left ventricular systolic dysfunction were more often male, had higher left ventricular mass index, and had worse predialysis left ventricular systolic function (left ventricular ejection fraction). The course of blood volume, BP, heart rate, electrolytes, and acid–base parameters during dialysis did not differ significantly between the two groups. Patients with hemodialysis-induced regional left ventricular systolic dysfunction had a significantly higher mortality after correction for age, sex, dialysis vintage, diabetes, cardiovascular history, ultrafiltration volume, left ventricular mass index, and predialysis wall motion score index. Conclusions Hemodialysis induces regional wall motion abnormalities in a significant proportion of patients, and these changes are independently associated with increased mortality. Hemodialysis-induced regional left ventricular systolic dysfunction occurs early during hemodialysis and is not related to changes in blood volume, electrolytes, and acid–base parameters. PMID

  11. A community-based model of care improves blood pressure control and delays progression of proteinuria, left ventricular hypertrophy and diastolic dysfunction in Maori and Pacific patients with type 2 diabetes and chronic kidney disease: a randomized controlled trial.

    Science.gov (United States)

    Hotu, Cheri; Bagg, Warwick; Collins, John; Harwood, Lorraine; Whalley, Gillian; Doughty, Robert; Gamble, Greg; Braatvedt, Geoffrey

    2010-10-01

    In this study, our main goal was to determine whether an integrated, community-based model of care using culturally appropriate health-care assistants to manage hypertension in Māori and Pacific patients with diabetes and chronic kidney disease (CKD) is more effective than conventional care in achieving blood pressure (BP) targets and delaying progression of cardiac and renal end-organ damage. Sixty-five Māori and Pacific patients (aged 47-75 years) with type 2 diabetes, moderate CKD (>0.5 g proteinuria/day, serum creatinine 130-300 µmol/l) and hypertension were randomized to usual care (n = 32) or community/intervention care (n = 33) for 12 months. Community care patients were visited monthly by a nurse-led health-care assistant for BP measurement. Antihypertensives were adjusted using a stepwise protocol, aiming for a BP systolic BP (-21 ± 26 mmHg vs -12 ± 20 mmHg, P = 0.04) and in 24-h urine protein (-1.4 ± 2.6 g vs +0.1 ± 2.8 g, P = 0.04). The number of prescribed antihypertensives was greater in these patients at 12 months (3.4 ± 1.1 vs 2.3 ± 1.0, P systolic BP and reducing cardiac and renal end-organ damage in these high-risk patients.

  12. Hemodynamic Performance of a Novel Right Ventricular Assist Device (PERKAT)

    Science.gov (United States)

    Schulze, P. Christian; Ferrari, Markus W.

    2017-01-01

    Acute right ventricular failure (RVF) is an increasing clinical problem and a life-threatening condition. Right ventricular assist devices represent a reasonable treatment option for patients with refractory RVF. We here present a novel percutaneously implantable device for right ventricular support. The PERKAT device is based on a nitinol stent cage, which is covered with valve-carrying foils. A flexible outlet trunk with a pigtail tip is connected to the distal part. The device is driven by an intra-aortic balloon pump (IABP) drive unit, which inflates/deflates a standard IABP-balloon placed within the stent cage. In-vitro evaluation was done in a liquid bath containing water or blood analog. The PERKAT device was tested in different afterload settings using two different IABP-balloons and varying inflation/deflation rates. We detected flow rates ranging from 1.97 to 3.93 L/min depending on the afterload setting, inflation/deflation rate, balloon size, and the medium used. Flow rates between water and blood analog were nearly comparable, and in the higher inflation/deflation rate settings slightly higher with water. Based on this promising in vitro data, the innovative percutaneously implantable PERKAT device has a potential to become a therapeutic option for patients with RVF refractory to medical treatment. PMID:27831998

  13. Assessment of right ventricular afterload in mitral valve diseases with radionuclide angiography

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Mitsuharu; Nakagawa, Tomio; Kohno, Yoshihiro; Kuroda, Masahiro; Takeda, Yoshihiro; Hiraki, Yoshio; Nagaya, Isao; Senoh, Yoshimasa; Teramoto, Shigeru (Okayama Univ. (Japan). School of Medicine)

    1991-02-01

    Right ventricular function at rest and during exercise was studied in 33 patients with mitral valve disease by equilibrium gated radionuclide angiography using {sup 99m}Tc in vivo labeled red blood cells. Radionuclide measurements of right ventricular ejection fraction (RVEF) were correlated with mean pulmonary arterial pressure (mPAP). RVEF decreased significantly with exercise. There was no significant correlation between RVEF at rest and mPAP. However, mPAP showed significant negative correlation with RVEF during exercise and with the changes of RVEF from rest to exercise. It is concluded that RVEF during exercise in mitral valve disease is affected by right ventricular afterload, and the measurements of RVEF at rest and during exercise by equilibrium gated radionuclide angiography is useful to assess right ventricular afterload. (author).

  14. Congenital left ventricular apical aneurysm presenting as ventricular tachycardia.

    Science.gov (United States)

    Amado, José; Marques, Nuno; Candeias, Rui; Gago, Paula; de Jesus, Ilídio

    2016-10-01

    The authors present the case of a 34-year-old male patient seen in our department due to palpitations. On the electrocardiogram monomorphic ventricular tachycardia (VT) was documented, treated successfully with amiodarone. The subsequent study revealed a normal echocardiogram and an apical aneurysm of the left ventricle on magnetic resonance imaging, confirmed by computed tomography coronary angiography that also excluded coronary disease. He underwent an electrophysiological study to determine the origin of the VT and to perform catheter ablation using electroanatomical mapping. VT was induced and radiofrequency applications were performed in the left ventricular aneurysm area. VT was no longer inducible, with acute success. Despite this it was decided to implant a subcutaneous implantable cardioverter-defibrillator (ICD). Eight months after the ablation the patient was admitted again due to VT, treated by the ICD. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. [Posterior ventricular septal perforation successfully repaired through right ventricular approach].

    Science.gov (United States)

    Takeuchi, Kazuma; Morishige, N; Iwahashi, H; Hayashida, Y; Teshima, H; Ito, N; Tashiro, T

    2006-12-01

    A 65-year-old man underwent a successful repair of a posterior ventricular septal perforation (VSP) 9 days after suffering an acute inferior myocardial infarction. After hospitalization, his hemodynamic condition gradually worsened, in spite of administering intensive medical therapy. Emergent operation was performed on the 4th day after onset. An equine pericardial patch was sutured around the VSP through the right ventricular side of the septum using the double-patch repair method and the right ventricular wall was closed as using the standard extracorporeal perfusion technique. The dimensions of the VSP measured 5 mm in diameter. Transesophageal echocardiography was performed on the 14th postoperative day. Cardiac catheter examination was done on the 18th postoperative day. No residual shunt was recognized and cardiac function was good. He was discharged on the 20th postoperative day. The occurrence of a posterior VSP is comparatively rare, and repair of VSP is difficult to perform during an acute period. Therefore, the operative results of VSP cases remain poor.

  16. Potential Vorticity Evolution in the Co-orbital Region of Embedded Protoplanets

    Energy Technology Data Exchange (ETDEWEB)

    Koller, J. [Rice Univ., Houston, TX (United States)

    2004-04-01

    This thesis presents two-dimensional hydrodynamic disk simulations with embedded protoplanets, emphasizing the non-linear dynamics in the co-orbital region. In particular, it demonstrates how a protoplanetary disk responds to embedded low mass planets at the inviscid limit. Since the potential vorticity (PV) flow is not conserved, due to the spiral shocks and possibly boundary layer effects emanating from the planet, the PV profile develops inflection points which eventually render the flow unstable. Vortices are produced in association with the potential vorticity minima. Born in the separatrix region, these vortices experience close encounters with the planet, consequently exerting strong torques on the planet. The existence of these vortices, if confirmed, have important implications on planetary migration rates. The formation of vortices is discussed in more detail and a key parameter is found which depends solely on planet mass and sound speed. With this key parameter, one can predict the disk evolution, PV growth rates, and threshold conditions for forming vortices in the co-orbital region. An analytical estimate for the change of PV due to shocks is compared to the actual change in PV in the hydrodynamic simulations. They match well except in the inner region where vortices form. In addition, extensive resolution tests were carried out but uncertainties remain about the physics of this particular region.

  17. Effect of potential vorticity flux on the circulation in the South China Sea

    Science.gov (United States)

    Zhu, Yaohua; Sun, Junchuan; Wang, Yonggang; Wei, Zexun; Yang, Dezhou; Qu, Tangdong

    2017-08-01

    This study analyzes temperature and salinity products from the U.S. Navy Generalized Digital Environment Model. To avoid the fictitious assumption of no-motion reference level, a P-vector inverse method is employed to derive geostrophic velocity. Line integral of geostrophic velocity shows evidence for the existence of a sandwiched circulation in the South China Sea (SCS), i.e., cyclonic circulation in the subsurface and deep layers and anticyclonic in the intermediate layer. To reveal the factors responsible for the sandwiched circulation, we derive the potential vorticity equation based on a four-and-a-half-layer quasi-geostrophic model and apply theoretical potential vorticity constraint to density layers. The result shows that the sandwiched circulation is largely induced by planetary potential vorticity flux through lateral boundaries, mainly the Luzon Strait. This dynamical mechanism lies in the fact that the net potential vorticity inflow in the subsurface and deep layers leads to a positive layer-average vorticity in the SCS basin, yielding vortex stretching and a cyclonic basin-wide circulation. On the contrary, the net potential vorticity outflow in the intermediate layer induces a negative layer-average vorticity, generating an anticyclonic basin-wide circulation in the SCS. Furthermore, by illustrating different consequence from depth/density layers, we clarify that density layers are essential for applying theoretical potential vorticity constraint to the isolated deep SCS basin.

  18. Dynamics of fractional vortices in long Josephson junctions; Dynamik fraktionaler Flusswirbel in langen Josephsonkontakten

    Energy Technology Data Exchange (ETDEWEB)

    Gaber, Tobias

    2007-07-01

    In this thesis static and dynamic properties of fractional vortices in long Josephson junctions are investigated. Fractional vortices are circulating supercurrents similar to the well-known Josephson fluxons. Yet, they show the distinguishing property of carrying only a fraction of the magnetic flux quantum. Fractional vortices are interesting non-linear objects. They spontaneously appear and are pinned at the phase discontinuity points of so called 0-{kappa} junctions but can be bend or flipped by external forces like bias currents or magnetic fields. 0-{kappa} junctions and fractional vortices are generalizations of the well-known 0-{pi} junctions and semifluxons, where not only phase jumps of pi but arbitrary values denoted by kappa are considered. By using so-called artificial 0-{kappa} junctions that are based on standard Nb-AlO{sub x}-Nb technology the classical dynamics of fractional vortices has been investigated experimentally for the very first time. Here, half-integer zero field steps could be observed. These voltage steps on the junction's current-voltage characteristics correspond to the periodic flipping/hopping of fractional vortices. In addition, the oscillatory eigenmodes of fractional vortices were investigated. In contrast to fluxons fractional vortices have an oscillatory eigenmode with a frequency within the plasma gap. Using resonance spectroscopy the dependence of the eigenmode frequency on the flux carried by the vortex and an applied bias current was determined. (orig.)

  19. A numerical study of the role of the vertical structure of vorticity during tropical cyclone genesis

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, T N [Flosolver Unit, National Aerospace Laboratories, PO Box 1779, Bangalore 560017 (India); Mathew, Joseph, E-mail: tnv@flosolver.nal.res.i, E-mail: joseph@aero.iisc.ernet.i [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India)

    2010-08-15

    An eight-level axisymmetric model with simple parameterizations for clouds and the atmospheric boundary layer was developed to examine the evolution of vortices that are precursors to tropical cyclones. The effect of vertical distributions of vorticity, especially that arising from a merger of mid-level vortices, was studied by us to provide support for a new vortex-merger theory of tropical cyclone genesis. The basic model was validated with the analytical results available for the spin-down of axisymmetric vortices. With the inclusion of the cloud and boundary layer parameterizations, the evolution of deep vortices into hurricanes and the subsequent decay are simulated quite well. The effects of several parameters such as the initial vortex strength, radius of maximum winds, sea-surface temperature and latitude (Coriolis parameter) on the evolution were examined. A new finding is the manner in which mid-level vortices of the same strength decay and how, on simulated merger of these mid-level vortices, the resulting vortex amplifies to hurricane strength in a realistic time frame. The importance of sea-surface temperature on the evolution of full vortices was studied and explained. Also it was found that the strength of the surface vortex determines the time taken by the deep vortex to amplify to hurricane strength.

  20. Imparting small vorticity to a Bianchi type-VIh empty spacetime

    Science.gov (United States)

    Batakis, Nikos A.

    1981-04-01

    We present and briefly discuss a Bianchi type-VIh empty spacetime. The field equations have been solved after being linearized with respect to a parameter which imparts vorticity to the model. The limit of zero vorticity is an already known solution.

  1. Diabetes Mellitus Associates with Increased Right Ventricular Afterload and Remodeling in Pulmonary Arterial Hypertension.

    Science.gov (United States)

    Whitaker, Morgan E; Nair, Vineet; Sinari, Shripad; Dherange, Parinita; Natarajan, Balaji; Trutter, Lindsey; Brittain, Evan L; Hemnes, Anna R; Austin, Eric; Patel, Kumar; Black, Stephen M; Garcia, Joe G N; Yuan, Jason X; Vanderpool, Rebecca; Rischard, Franz; Makino, Ayako; Bedrick, Edward J; Desai, Ankit A

    2018-02-05

    Diabetes mellitus is associated with left ventricular hypertrophy and dysfunction. Parallel studies have also reported associations between diabetes mellitus and right ventricle dysfunction and reduced survival in patients with pulmonary arterial hypertension. However, the impact of diabetes mellitus on the pulmonary vasculature has not been well-characterized. We hypothesized that diabetes mellitus and hyperglycemia could specifically influence right ventricular afterload and remodeling in patients with Group I pulmonary arterial hypertension, providing a link to their known susceptibility to right ventricular dysfunction. Using an adjusted model for age, gender, pulmonary vascular resistance, and medication use, associations of fasting blood glucose, glycated hemoglobin, and the presence of diabetes mellitus were evaluated with markers of disease severity in 162 patients with pulmonary arterial hypertension. A surrogate measure of increased pulmonary artery stiffness, elevated pulmonary arterial elastance (P=0.012), along with reduced log(pulmonary artery capacitance) (P=0.006) were significantly associated with the presence of diabetes mellitus in patients with pulmonary arterial hypertension in a fully adjusted model. Similar associations between pulmonary arterial elastance and capacitance were noted with both fasting blood glucose and glycated hemoglobin. Furthermore, right ventricular wall thickness on echocardiography was greater in pulmonary arterial hypertension patients with diabetes, supporting the link between right ventricular remodeling and diabetes. Cumulatively, these data demonstrate that an increase in right ventricular afterload, beyond pulmonary vascular resistance alone, may influence right ventricular remodeling and provide a mechanistic link between the susceptibility to right ventricular dysfunction in patients with both diabetes mellitus and pulmonary arterial hypertension. Copyright © 2018. Published by Elsevier Inc.

  2. Fluid-dynamic modeling of the human left ventricle: methodology and application to surgical ventricular reconstruction.

    Science.gov (United States)

    Doenst, Torsten; Spiegel, Kathrin; Reik, Michael; Markl, Michael; Hennig, Jürgen; Nitzsche, Stefan; Beyersdorf, Friedhelm; Oertel, Herbert

    2009-04-01

    The efficacy of surgical ventricular reconstruction (SVR) for ischemic cardiomyopathy has never been truly quantified. Methods to assess ventricular flow have not been applied to these patients. The objective is to develop a volume-independent technique for assessing the effects of ischemic remodeling and SVR on left ventricular blood flow dynamics. Cardiac magnetic resonance images from a healthy volunteer and from a patient before and after SVR were segmented and transformed to generate a grid model of the heart by generating numeric grids and running third-order approximations to achieve 850 grid images per cardiac cycle. These grids formed the skeletal structure of our patient-specific time-dependent ventricular geometry model, the Karlsruhe Heart Model, used for modeling fluid dynamics. We modeled flow, ejection fraction, and blood washout from the ventricle. The model was validated using a silicone ventricle and mock circulation. In the healthy heart and before SVR, ejection fractions were 0.61 and 0.15 and left ventricular volumes were 166 mL and 175 mL, respectively. Surgical ventricular reconstruction decreased left ventricular volume by one fourth. Postoperative ejection fraction was 0.18 in the patient. Post-SVR shape was more spherical than preoperatively and also more spherical than the healthy heart. Ventricular flow patterns in the patient were significantly altered by SVR. However, fluid washout from the ventricle was similar before and after SVR but worse than in the healthy heart. Fluid dynamic modeling of the heart is possible based on cardiac magnetic resonance imaging data and enables volume-independent quantitative assessment of the surgical procedure. In the future, preoperative modeling for patients with remodeled ventricles may help to achieve optimized post-SVR flow characteristics and potentially outcomes.

  3. Dynamic manipulation of asymmetric forebody vortices to achieve linear control

    Science.gov (United States)

    Lee, Richard

    A wind tunnel experiment was performed to further investigate the potential of the dynamic manipulation of forebody vortices as a means of supplementing directional control of fighter aircraft at high angles of attack. Tests were conducted on a 65-deg delta-wing model fitted with a slender, pointed tangent-ogive forebody of circular cross-section and 12.8 deg semi-apex angle. Forward-blowing nozzles located near the apex of the forebody served as the means of manipulating the forebody vortices. As expected, forward blowing was very effective, i.e., little blowing effort was required to cause the forebody vortex on the blown side to assume the 'high' position. However, the magnitudes of yawing moment and side force developed by the slender forebody with blowing do not differ significantly from that of the no-blowing, baseline case. Moreover, blowing above a certain threshold value produced an unexpected reversal, with blowing causing the vortex on the blown side to assume the 'low' position instead and the yawing moment and side force to change sense. The results have shown that the dynamic manipulation scheme is very successful in producing a linear variation of time-average yawing moment with a duty-cycle parameter, even with sideslip, for the aircraft-like model. The results also show that, by switching the vortex pattern rapidly, the linearity can be maintained up to a reduced frequency of at least 0.32, which is expected to be very satisfactory for practical applications. A subsequent water tunnel experiment with the forebody alone was undertaken to conduct off-surface flow visualizations that confirmed the vortex reversal phenomenon. Based on the flow visualization studies, a hypothesis was formed regarding the cause of the reversal phenomenon; it postulates that at the reversal threshold the nozzle flux interrupts the formation of the high forebody vortex on the blowing side and encourages the shear layer to form a replacement vortex that lies close to the

  4. Matter in the form of toroidal electromagnetic vortices

    Science.gov (United States)

    Hagen, Wilhelm F.

    2015-09-01

    The creation of charged elementary particles from neutral photons is explained as a conversion process of electromagnetic (EM) energy from linear to circular motion at the speed of light into two localized, toroidal shaped vortices of trapped EM energy that resist change of motion, perceptible as particles with inertia and hence mass. The photon can be represented as a superposition of left and right circular polarized transverse electric fields of opposite polarity originating from a common zero potential axis, the optical axis of the photon. If these components are separated by interaction with a strong field (nucleon) they would curl up into two electromagnetic vortices (EMV) due to longitudinal magnetic field components forming toroids. These vortices are perceptible as opposite charged elementary particles e+/- . These spinning toroids generate extended oscillating fields that interact with stationary field oscillations. The velocity-dependent frequency differences cause beat signals equivalent to matter waves, leading to interference. The extended fields entangled with every particle explain wave particle duality issues. Spin and magnetic moment are the natural outcome of these gyrating particles. As the energy and hence mass of the electron increases with acceleration so does its size shrink proportional to its reduced wavelength. The artificial weak and strong nuclear forces can be easily explained as different manifestations of the intermediate EM forces. The unstable neutron consists of a proton surrounded by a contracted and captured electron. The associated radial EM forces represent the weak nuclear force. The deuteron consists of two axially separated protons held together by a centrally captured electron. The axial EM forces represent the strong nuclear force, providing stability for "neutrons" only within nucleons. The same principles were applied to determine the geometries of force-balanced nuclei. The alpha-particle emerges as a very compact

  5. Diagnostic study on the relation between ozone and vorticity potential

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Basset, H. [Department of Astronomy and Meteorology, Faculty of Science, Al Azhar University, Nasr City, Cairo (Egypt); Gahein, A. [Egyptian Meteorological Authority, Cairo (Egypt)

    2003-04-01

    A diagnostic analysis of a Mediterranean system and the associated tropopause folding for the period 27 February to 10 March, 1987 is presented. Geopotential height, potential vorticity (PV) and relative humidity distributions were diagnosed. The analysis indicates clear correlation between the development of the cut-off low and the tropopause folding. A series of vertical cross-sections at the ends of the jet streaks demonstrated that a fold could be captured using potential vorticity and relative humidity. Q-vectors were employed to investigate vertical motion in the vicinity of the fold and showed the exact positions of descent corresponding to the fold along the entire length of the jet streak. The analysis also shows that the strong correlation between total ozone and column integrated vorticity potential holds well for all levels. As both quantities are integrals through the atmosphere, this result is consistent with, but does not prove, a high independent linear dependence between ozone and PV. More case studies are needed to assure the high linear dependence between ozone and PV. The maximum transport of ozone from the stratosphere to the troposphere is coinciding with the maximum developing system, and also with the maximum values of PV. [Spanish] Se presenta un analisis diagnostico de un Sistema mediterraneo y del pliegue de la tropopausa asociado durante el periodo del 27 de febrero al 10 de marzo de 1987. Se diagnosticaron la altitud neopotencial, el potencial de vorticidad y la distribucion de la humedad relativa. El analisis indica una correlacion clara entre el desarrollo de la baja segregada y el pliegue de la tropopausa. Una serie de cortes verticales en los extremos de las trazas del chorro demostraron que el pliegue puede ser capturado utilizando el potencial de vorticidad y la humedad relativa. Para investigar la movilidad vertical en la vecindad del pliegue se utilizaron vectores Q, y se demostraron las posiciones exactas de descenso

  6. Analysis of scalar dissipation in terms of vorticity geometry in isotropic turbulence

    CERN Document Server

    Gonzalez, Michel

    2016-01-01

    The mechanisms promoting scalar dissipation through scalar gradient production are scrutinized in terms of vorticity alignment with respect to strain principal axes. For that purpose, a stochastic Lagrangian model for the velocity gradient tensor and the scalar gradient vector is used. The model results show that the major part of scalar dissipation occurs for stretched vorticity, namely when the vorticity vector aligns with the extensional and intermediate strain eigenvectors. More specifically, it appears that the mean scalar dissipation is well represented by the sample defined by alignment with the extensional strain, while the most intense scalar dissipation is promoted by the set of events for which vorticity aligns with the intermediate strain. This difference is explained by rather subtle mechanisms involving the statistics of both the strain intensities and the scalar gradient alignment resulting from these special alignments of vorticity. The analysis allowing for the local flow structure confirms t...

  7. Vortical Motions of Baryonic Gas in the Cosmic Web: Growth History and Scaling Relation

    Science.gov (United States)

    Zhu, Weishan; Feng, Long-long

    2015-10-01

    The vortical motions of the baryonic gas residing in large-scale structures are investigated by cosmological hydrodynamic simulations. Proceeding in the formation of the cosmic web, the vortical motions of baryonic matter are pumped up by baroclinity in two stages, i.e., the formation of sheets and filaments. The mean curl velocities are about filaments, and knots at z = 0, respectively. The scaling of the vortical velocity of gas can be well described by the She-Leveque hierarchical turbulence model in the range of l filaments, Df ˜ 1.9-2.2, and smaller than the fractal dimension of sheets, Ds ˜ 2.4-2.7. The vortical kinetic energy of baryonic gas is mainly transported by filaments. Both scalings of mass distribution and vortical velocity increments show distinctive transitions at the turning scale of ˜0.65(1.50) h-1 Mpc, which may be closely related to the characteristic radius of density filaments.

  8. Numerical and Experimental Study on Negative Buoyance Induced Vortices in N-Butane Jet Flames

    KAUST Repository

    Xiong, Yuan

    2015-07-26

    Near nozzle flow field in flickering n-butane diffusion jet flames was investigated with a special focus on transient flow patterns of negative buoyance induced vortices. The flow structures were obtained through Mie scattering imaging with seed particles in a fuel stream using continuous-wave (CW) Argon-ion laser. Velocity fields were also quantified with particle mage velocimetry (PIV) system having kHz repetition rate. The results showed that the dynamic motion of negative buoyance induced vortices near the nozzle exit was coupled strongly with a flame flickering instability. Typically during the flame flickering, the negative buoyant vortices oscillated at the flickering frequency. The vortices were distorted by the flickering motion and exhibited complicated transient vortical patterns, such as tilting and stretching. Numerical simulations were also implemented based on an open source C++ package, LaminarSMOKE, for further validations.

  9. Indirect Combustion Noise: Noise Generation by Accelerated Vorticity in a Nozzle Flow

    Directory of Open Access Journals (Sweden)

    Nancy Kings

    2010-09-01

    Full Text Available The noise generation by accelerated vorticity waves in a nozzle flow was investigated in a model experiment. This noise generation mechanism belongs, besides entropy noise, to the indirect combustion noise phenomena. Vorticity as well as entropy fluctuations, originating from the highly turbulent combustion zone, are convected with the flow and produce noise during their acceleration in the outlet nozzle of the combustion chamber. In the model experiment, noise generation of accelerated vorticity fluctuations was achieved. The vorticity fluctuations in the tube flow were produced by injecting temporally additional air into the mean flow. As the next step, a parametric study was conducted to determine the major dependencies of the so called vortex noise. A quadratic dependency of the vortex noise on the injected air amount was found. In order to visualise and classify the artificially generated vorticity structures, planar velocity measurements have been conducted applying Particle Image Velocimetry (PIV.

  10. Prophylactic implantable defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation or sustained ventricular tachycardia.

    LENUS (Irish Health Repository)

    Corrado, Domenico

    2010-09-21

    The role of implantable cardioverter-defibrillator (ICD) in patients with arrhythmogenic right ventricular cardiomyopathy\\/dysplasia and no prior ventricular fibrillation (VF) or sustained ventricular tachycardia is an unsolved issue.

  11. Left ventricular aneurysm associated with isolated noncompaction of the ventricular myocardium.

    Science.gov (United States)

    Sato, Yuichi; Matsumoto, Naoya; Yoda, Shunichi; Inoue, Fumio; Kunimoto, Satoshi; Fukamizu, Seiji; Tani, Shigemasa; Takayama, Tadateru; Tokai, Kotaro; Kasamaki, Yuji; Saito, Satoshi; Uchiyama, Takahisa; Koyama, Yasushi

    2006-05-01

    A 66-year-old woman was admitted to our hospital because of left ventricular failure and nonsustained ventricular tachycardia. Two-dimensional echocardiography demonstrated prominent trabeculations and deep intertrabecular recesses, findings consistent with noncompaction of the ventricular myocardium. Myocardial perfusion scintigraphy demonstrated a defect in the anterobasal left ventricular segment. Coronary angiogram was normal, but the left ventriculogram showed an aneurysm in the anterior myocardial segments. This is the first reported case with isolated noncompaction of the ventricular myocardium associated with left ventricular aneurysm.

  12. May Fever Trigger Ventricular Fibrillation?

    Directory of Open Access Journals (Sweden)

    Jean Luc Pasquié

    2005-04-01

    Full Text Available The clinical precipitants of ventricular fibrillation (VF remain poorly understood. Clinical factors such as hypoxemia, acidosis or electrolyte imbalance, drug-related toxicity, autonomic nervous system disorders as well as viral myocarditis have been proposed to be associated with sudden cardiac death particularly in patients with structural heart disease. However, In the Brugada syndrome, concurrent febrile illness has been reported to unmask the electrocardiographic features of the Brugada syndrome and be associated with an increased propensity for VF. More recently, a febrile illnesses of infectious etiology was associated to polymorphic ventricular tachycardia or VF in patients with normal hearts and without known repolarization abnormality. In this review we detail this phenomenon and its putative mechanisms.

  13. Correlation analysis on volume vorticity and vortex in late boundary layer transition

    Science.gov (United States)

    Dong, Xiangrui; Tian, Shuling; Liu, Chaoqun

    2018-01-01

    In this paper, two functions are introduced to describe the turbulence generation in late flow transition. One is called the volume omega bar (volume Ω ¯ ), which represents the flow rotation or vortex strength. The other is called the volume vorticity, which shows the flow statistical fluctuations. Although they have very different definitions, one is for fluctuation and the other is for rotation, volume Ω ¯ and volume vorticity are found highly correlated with a correlation factor greater than 0.9, which means that there is a very close correlation between flow fluctuation and flow rotation (vortex). While the vorticity flux keeps constant in the late flow transition through the integration over any sections either parallel or perpendicular to the flow direction, the volume Ω ¯ is greatly increased along the flow direction during the flow transition process. This means that the vortex structures are greatly built up and rotation becomes more and more dominant. On the other hand, the total volume vorticity is also quickly increased, which shows that the fluctuation is stronger. The flow transition is a process with significant volume vorticity increase, which is attributed to two of the following crucial factors: the first one is the lengthening of the vorticity tubes from side boundary due to the vorticity line stretching, distortion, and tangling; the second one is the generation of countless self-closed vorticity rings within the domain. Both the increase of the volume vorticity and the volume Ω ¯ can be a significant symbol of the flow transition from the laminar flow to turbulent flow. It also shows that vorticity (tubes or lines) cannot directly represent vortex and should not be simply used as a signal of the turbulent transition process.

  14. Population, characteristics and kinematics of vortices in a confined rectangular jet with a co-flow

    Science.gov (United States)

    Kong, B.; Olsen, M. G.; Fox, R. O.; Hill, J. C.

    2011-06-01

    Vortex behavior and characteristics in a confined rectangular jet with a co-flow were examined using vortex swirling strength as a defining characteristic. On the left side of the jet, the positively (counterclockwise) rotating vortices are dominant, while negatively rotating vortices are dominant on the right side of the jet. The characteristics of vortices, such as population density, average size and strength, and deviation velocity, were calculated and analyzed in both the cross-stream direction and the streamwise direction. In the near-field of the jet, the population density, average size and strength of the dominant direction vortices show high values on both sides of the center stream with a small number of counter-rotating vortices produced in the small wake regions close to jet outlet. As the flow develops, the wake regions disappear, these count-rotating vortices also disappear, and the population of the dominant direction vortices increase and spread in the jet. The mean size and strength of the vortices decrease monotonically with streamwise coordinate. The signs of vortex deviation velocity indicate the vortices transfer low momentum to high-velocity region and high momentum to the low velocity region. The developing trends of these characteristics were also identified by tracing vortices using time-resolved particle image velocimetry data. Both the mean tracked vortex strength and size decrease with increasing downstream distance overall. At the locations of the left peak of turbulent kinetic energy, the two-point spatial cross-correlation of swirling strength with velocity fluctuation and concentration fluctuation were calculated. All the correlation fields contain one positively correlated region and one negatively correlated region although the orientations of the correlation fields varied, due to the flow transitioning from wake, to jet, to channel flow. Finally, linear stochastic estimation was used to calculate conditional structures. The large

  15. Aerodynamic and acoustic effects of ventricular gap.

    Science.gov (United States)

    Alipour, Fariborz; Karnell, Michael

    2014-03-01

    Supraglottic compression is frequently observed in individuals with dysphonia. It is commonly interpreted as an indication of excessive circumlaryngeal muscular tension and ventricular medialization. The purpose of this study was to describe the aerodynamic and acoustic impact of varying ventricular medialization in a canine model. Subglottal air pressure, glottal airflow, electroglottograph, acoustic signals, and high-speed video images were recorded in seven excised canine larynges mounted in vitro for laryngeal vibratory experimentation. The degree of gap between the ventricular folds was adjusted and measured using sutures and weights. Data were recorded during phonation when the ventricular gap was narrow, neutral, and large. Glottal resistance was estimated by measures of subglottal pressure and glottal flow. Glottal resistance increased systematically as ventricular gap became smaller. Wide ventricular gaps were associated with increases in fundamental frequency and decreases in glottal resistance. Sound pressure level did not appear to be impacted by the adjustments in ventricular gap used in this research. Increases in supraglottic compression and associated reduced ventricular width may be observed in a variety of disorders that affect voice quality. Ventricular compression may interact with true vocal fold posture and vibration resulting in predictable changes in aerodynamic, physiological, acoustic, and perceptual measures of phonation. The data from this report supports the theory that narrow ventricular gaps may be associated with disordered phonation. In vitro and in vivo human data are needed to further test this association. Copyright © 2014 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

  16. Topological vortices in generalized Born-Infeld-Higgs electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Casana, R. [Universidade Federal do Maranhao, Departamento de Fisica, Sao Luis, Maranhao (Brazil); Hora, E. da [Universidade Federal do Maranhao, Departamento de Fisica, Sao Luis, Maranhao (Brazil); Universidade Federal do Maranhao, Coordenadoria Interdisciplinar de Ciencia e Tecnologia, Sao Luis, Maranhao (Brazil); Rubiera-Garcia, D. [Fudan University, Department of Physics, Center for Field Theory and Particle Physics, Shanghai (China); Santos, C. dos [Faculdade de Ciencias da Universidade do Porto, Centro de Fisica e Departamento de Fisica e Astronomia, Porto (Portugal)

    2015-08-15

    A consistent BPS formalism to study the existence of topological axially symmetric vortices in generalized versions of the Born-Infeld-Higgs electrodynamics is implemented. Such a generalization modifies the field dynamics via the introduction of three nonnegative functions depending only in the Higgs field, namely,G(vertical stroke φ vertical stroke), w(vertical stroke φ vertical stroke), and V (vertical stroke φ vertical stroke). A set of first-order differential equations is attained when these functions satisfy a constraint related to the Ampere law. Such a constraint allows one to minimize the system's energy in such way that it becomes proportional to the magnetic flux. Our results provides an enhancement of the role of topological vortex solutions in Born-Infeld-Higgs electrodynamics. Finally, we analyze a set of models entailing the recovery of a generalized version of Maxwell-Higgs electrodynamics in a certain limit of the theory. (orig.)

  17. Driven phase space vortices in plasmas with nonextensive velocity distribution

    Science.gov (United States)

    Trivedi, Pallavi; Ganesh, Rajaraman

    2017-03-01

    The evolution of chirp-driven electrostatic waves in unmagnetized plasmas is numerically investigated by using a one-dimensional (1D) Vlasov-poisson solver with periodic boundary conditions. The initial velocity distribution of the 1D plasma is assumed to be governed by nonextensive q distribution [C. Tsallis, J. Stat. Phys. 52, 479 (1988)]. For an infinitesimal amplitude of an external drive, we investigate the effects of chirp driven dynamics that leads to the formation of giant phase space vortices (PSV) for both Maxwellian (q = 1) and non-Maxwellian ( q ≠ 1 ) plasmas. For non-Maxwellian plasmas, the formation of giant PSV with multiple extrema and phase velocities is shown to be dependent on the strength of "q". Novel features such as "shark"-like and transient "honeycomb"-like structures in phase space are discussed. Wherever relevant, we compare our results with previous work.

  18. Cubic nonlinear Schrödinger equation with vorticity

    Science.gov (United States)

    Caliari, M.; Loffredo, M. I.; Morato, L. M.; Zuccher, S.

    2008-12-01

    In this paper, we introduce a new class of nonlinear Schrödinger equations (NLSEs), with an electromagnetic potential (\\mathcal A,\\Phi) , both depending on the wavefunction Ψ. The scalar potential Φ depends on |Ψ|2, whereas the vector potential \\mathcal A satisfies the equation of magnetohydrodynamics with coefficient depending on Ψ. In Madelung variables, the velocity field comes to be not irrotational in general and we prove that the vorticity induces dissipation, until the dynamical equilibrium is reached. The expression of the rate of dissipation is common to all NLSEs in the class. We show that they are a particular case of the one-particle dynamics out of dynamical equilibrium for a system of N identical interacting Bose particles, as recently described within stochastic quantization by Lagrangian variational principle. The cubic case is discussed in particular. Results of numerical experiments for rotational excitations of the ground state in a finite two-dimensional trap with harmonic potential are reported.

  19. Vorticity Dynamics in Single and Multiple Swirling Reacting Jets

    Science.gov (United States)

    Smith, Travis; Aguilar, Michael; Emerson, Benjamin; Noble, David; Lieuwen, Tim

    2015-11-01

    This presentation describes an analysis of the unsteady flow structures in two multinozzle swirling jet configurations. This work is motivated by the problem of combustion instabilities in premixed flames, a major concern in the development of modern low NOx combustors. The objective is to compare the unsteady flow structures in these two configurations for two separate geometries and determine how certain parameters, primarily distance between jets, influence the flow dynamics. The analysis aims to differentiate between the flow dynamics of single nozzle and triple nozzle configurations. This study looks at how the vorticity in the shear layers of one reacting swirling jet can affect the dynamics of a nearby similar jet. The distance between the swirling jets is found to have an effect on the flow field in determining where swirling jets merge and on the dynamics upstream of the merging location. Graduate Student, School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA.

  20. Microalga propels along vorticity direction in a shear flow

    Science.gov (United States)

    Chengala, Anwar; Hondzo, Miki; Sheng, Jian

    2013-05-01

    Using high-speed digital holographic microscopy and microfluidics, we discover that, when encountering fluid flow shear above a threshold, unicellular green alga Dunaliella primolecta migrates unambiguously in the cross-stream direction that is normal to the plane of shear and coincides with the local fluid flow vorticity. The flow shear drives motile microalgae to collectively migrate in a thin two-dimensional horizontal plane and consequently alters the spatial distribution of microalgal cells within a given suspension. This shear-induced algal migration differs substantially from periodic rotational motion of passive ellipsoids, known as Jeffery orbits, as well as gyrotaxis by bottom-heavy swimming microalgae in a shear flow due to the subtle interplay between torques generated by gravity and viscous shear. Our findings could facilitate mechanistic solutions for modeling planktonic thin layers and sustainable cultivation of microalgae for human nutrition and bioenergy feedstock.

  1. Resonance of Brownian vortices in viscoelastic shear flows

    Science.gov (United States)

    Laas, K.; Mankin, R.

    2015-10-01

    The dynamics of a Brownian particle in an oscillatory viscoelastic shear flow is considered using the generalized Langevin equation. The interaction with fluctuations of environmental parameters is modeled by an additive external white noise and by an internal Mittag-Leffer noise with a finite memory time. Focusing on the mean angular momentum of particles it is shown that the presence of memory has a profound effect on the behavior of the Brownian vortices. Particularly, if an external noise dominates over the internal noise, a resonance-like dependence of the mean angular momentum of "free" particles, trapped due to the cage effect, on the characteristic memory time is observed. Moreover, it is established that memory effects can induce two kinds of resonance peaks: one resonance peak is related to the presence of external noise and the other is related to the initial positional distribution of particles. The bona fide resonance versus the shear frequency is also discussed.

  2. Role of electric discharges in the generation of atmospheric vortices

    Science.gov (United States)

    Sinkevich, O. A.; Maslov, S. A.; Gusein-zade, N. G.

    2017-02-01

    The existing thermohydrodynamic and hydroelectromagnetic models of tornado are considered. The potentialities of the humid atmosphere as a heat engine generating air vortices are analyzed in detail. The ability of long-term atmospheric electric discharges to form a tornado funnel and create an initial twist of up to 10-3-10-2 s-1 in it are estimated. The possible effect of a lightning discharge on the initiation and evolution of the tornado is discussed. It is shown that the electric current flowing along the lightning channel can lead to helical instability and generation of a weak primary vortex. The channel formed in the atmosphere by a lightning discharge and the vortex motion of the parent thundercloud can enhance the primary vortex and promote its transformation into a tornado. Possible mechanisms of enhancement of the primary vortex created by a lightning discharge and the possibility of its transformation into a tornado in the postdischarge stage are discussed.

  3. Climate science in the tropics: waves, vortices and PDEs

    Science.gov (United States)

    Khouider, Boualem; Majda, Andrew J.; Stechmann, Samuel N.

    2013-01-01

    Clouds in the tropics can organize the circulation on planetary scales and profoundly impact long range seasonal forecasting and climate on the entire globe, yet contemporary operational computer models are often deficient in representing these phenomena. On the other hand, contemporary observations reveal remarkably complex coherent waves and vortices in the tropics interacting across a bewildering range of scales from kilometers to ten thousand kilometers. This paper reviews the interdisciplinary contributions over the last decade through the modus operandi of applied mathematics to these important scientific problems. Novel physical phenomena, new multiscale equations, novel PDEs, and numerical algorithms are presented here with the goal of attracting mathematicians and physicists to this exciting research area.

  4. Comparative value of Left ventricular function: Ecg-gated blood pool versus Ecg-gated myocardial perfusion single photon emission computed tomography; Valeur comparative de la tomoscintigraphie cavitaire versus myocardique par emission monophotonique synchronisee a l'ECG dans l'evaluation de la fonction ventriculaire gauche

    Energy Technology Data Exchange (ETDEWEB)

    Daou, D.; Coaguila, C.; Benada, A.; Idy Peretti, I. [Centre Hospitalier Universitaire Lariboisiere-Saint-Louis, Dept. de Medecine Nucleaire, 75 - Paris (France); Vilain, D. [Hopital Foch, Dept. de Medecine Nucleaire, 92 - Suresnes (France); Fourme, T.; Slama, M. [Centre Hospitalier Universitaire Antoine Beclere - AP-HP, Dept. de Cardiologie, 92 - Clamart (France); Lebtahi, R.; Le Guludec, D. [Centre Hospitalier Universitaire Bichat - AP-HP, Dept. de Medecine Nucleaire, 75 - Paris (France)

    2004-01-01

    Both electrocardiographically (ECG)-gated blood pool SPECT (GBPS) and ECG-gated myocardial perfusion SPECT (GSPECT) are validated for the measurement of global left ventricular (LV) function. We aimed to compare the value of GSPECT and GBPS for the measurement of global LV function. The population included 65 patients having both rest {sup 201}Tl GSPECT followed by planar (planar{sub RNA}) and GBPS equilibrium radionuclide angiography. Thirty-five patients had also a LV conventional contrast angiography (X-rays). LV ejection fraction (EF) and LV volume (end-diastolic-EDV and end-systolic-ESV volumes) were calculated with GBPS and GSPECT and compared to gold standards methods (planar{sub RNA} LVEF and X-rays LV volume). For both LVEF and LV volume, the interobserver variability was lower with GBPS than GSPECT. Planar{sub RNA} LVEF was slightly better correlated to GBPS than GSPECT. X-rays LV volume was slightly better correlated to GBPS than GSPECT. On stepwise regression analysis, the accuracy of GSPECT for the measurement of LV function was correlated to numerous different factors including planar{sub RNA} LVEF, signal to noise ratio, X-rays LV volume, summed rest score, and acquisition scanning distance. The accuracy of GBPS was only correlated to the signal level, signal to noise ratio, and acquisition scanning distance. Both GSPECT and GBPS provide reliable estimation of global LV function. The better reliability encountered with GBPS and in particular its lesser sensitivity to different variable factors as encountered with GSPECT favors its use when precise measurement of global LV function is clinically indicated. (author)

  5. HST and Keck AO Images of Vortices on Jupiter

    Science.gov (United States)

    de Pater, Imke; Wong, M.; Luszcz-Cook, S.; Adamkovics, M.; Marcus, P.; Asay-Davis, X.; Conrad, A.; Go, C.

    2009-09-01

    Observations of Jupiter were conducted in April 2006 and May 2008 with both HST (250-890 nm) and the 10-m Keck telescope. On Keck we used the near-infrared camera NIRC2, coupled to the AO system, at 1.2 to 5 micrometers. At 5 um we are sensitive to Jupiter's thermal emission in cloud-free regions of the atmosphere, while at 1.2 um we see reflected sunlight from hazes and clouds in the troposphere-stratosphere. All small ovals (i.e., all except for Oval BA and the GRS) appear to be surrounded by bright rings at 5 mu, with typical brightness temperatures of 225-250 K, and hence probing depths to 2.5-4 bar. We argue that the small vortices are columnar structures, extending down into the water cloud. Air is rising along the center of these vortices, and descending around the outer periphery; the storm systems are likely fueled by the latent heat released from the water cloud. The descending part of the vertical circulation in the larger ovals is within the ovals, likely at the location of the red ring in Oval BA, which may indicate the maximum radial distance where such return flows can take place. On 19 July 2009, amateur observer Anthony Wesley (Australia) reported a dark spot/streak on Jupiter, near a southern latitude of 56 deg, which he attributed to an impact (analogous to the SL9 impact on Jupiter). We are scheduled to observe Jupiter with the Keck AO system on 24 July 2009 UT; if observations are successful, we will report preliminary results.

  6. History of Research on Lift-Generated Vortices

    Science.gov (United States)

    Rossow, Vernon J.; Olson, Lawrence E. (Technical Monitor)

    1998-01-01

    A theoretical and experimental program on the structure and possible modification of lift-generated vortices shed by subsonic aircraft has been underway at NASA Ames Research Center since the late 1960's. The objectives of the program were to first obtain a better understanding of the hazard posed by the vortex wakes of subsonic transports, and then to develop methods on how to modify or design the wake-generating aircraft in order to make the vortices less hazardous. Some effort was also expended on the development of methods to avoid vortex wakes. The seminar will present a brief history of the research program beginning with the nature of vortex wakes and their relationship to the span loading on the wake-generating wing. Examples will then be presented to show how span-loading changes were used to influence the dynamics of the vortex wakes shed by subsonic transport aircraft. Video tape segments will be shown to illustrate the dynamics of vortex wakes and the flight tests carried out by NASA to find out how configurations developed in wind tunnels would perform on flight vehicles. The presentation will then summarize some recent results obtained in the 80- by 120-Foot Wind Tunnel at NASA Ames Research Center on the vortex wakes that trail from 0.03 scale models of a B-747 and of a DC-10 at downstream distances of 81 ft and 162 ft behind the wake-generating model; i.e., at scale distances of 0.5 and 1.0 mile. Lastly, a proposed vortex avoidance scheme based on the Global Positioning System will be described. All of the material to be presented is publically available in technical journals.

  7. Deep Coherent Vortices and Their Sea Surface Expressions

    Science.gov (United States)

    Ienna, Federico; Bashmachnikov, Igor; Dias, Joaquim; Peliz, Alvaro

    2017-04-01

    Mediterranean Water eddies, known as Meddies, are an important dynamic process occurring at depths of 1000-meters in the Northeast Atlantic Ocean. Meddies occur as a direct result of the Mediterranean Outflow exiting through the Gibraltar Strait, and represent a prevalent mechanism that can be found extensively throughout the ocean. Moreover, Meddy cores are known to produce measurable expressions at the sea surface in the form of rotating coherent vortices, not only affecting the sea surface from beneath, but also allowing for the possibility to remotely study these deep phenomena through data gathered at the sea surface. While many past studies have focused on the properties of Meddy cores, only a handful of studies focus on the physical characteristics and behavior of the surface expressions produced. Are Meddy surface expressions different from other like vortices that dominate the physical ocean surface? What are the relationships between deep and surface mechanisms, and do any feedbacks exist? To shed light on these questions, we investigate the relationship between Meddies and their sea-surface expressions through observations using in-situ float and drifter profiles and satellite altimetry. A total of 782 Meddy cores were examined in the Northeast Atlantic using temperature and salinity data obtained by CTD and Argo during the Mecanismos de transporte e de dispersão da Água Mediterrânica no Atlântico Nordeste (MEDTRANS) project, and their corresponding sea-level expressions were geo-temporally matched in satellite altimetry data. We report several statistical properties of the sea-surface expressions of Meddies, including their mean diameter and vertical magnitude, and compare the properties of their surface features to the underlying Meddy cores. We investigate how the deep core affects the surface, and whether surface expressions may in return yield information about the underlying cores. Additionally, we examine the variability of the surface

  8. Premature ventricular contractions associated with isotretinoin use.

    Science.gov (United States)

    Alan, Sevil; Ünal, Betül; Yildirim, Aytül

    2016-01-01

    Isotretinoin has been considered a unique drug for acne treatment. However, it is associated with numerous adverse effects. Isotretinoin can trigger premature ventricular contractions. This report describes a 33-year-old-woman who presented with palpitations for 1 week while undergoing 1-month isotretinoin treatment for mild-moderate facial acne. An electrocardiogram and Holter monitoring showed premature ventricular contractions during isotretinoin (Roaccutane, Roche) treatment. Isotretinoin-related premature ventricular contractions were strongly suggested in this case due to the existence of documented premature ventricular contractions on electrocardiograms and the disappearance of these premature ventricular contractions two weeks after termination of the treatment To the authors' knowledge, there has been 1 reported case of premature ventricular contractions linked to isotretinoin use; this report describes a second such case.

  9. Correlation between vortices and wall shear stress in a curved artery model under pulsatile flow conditions

    Science.gov (United States)

    Cox, Christopher; Plesniak, Michael W.

    2017-11-01

    One of the most physiologically relevant factors within the cardiovascular system is the wall shear stress. The wall shear stress affects endothelial cells via mechanotransduction and atherosclerotic regions are strongly correlated with curvature and branching in the human vasculature, where the shear stress is both oscillatory and multidirectional. Also, the combined effect of curvature and pulsatility in cardiovascular flows produces unsteady vortices. In this work, our goal is to assess the correlation between multiple vortex pairs and wall shear stress. To accomplish this, we use an in-house high-order flux reconstruction Navier-Stokes solver to simulate pulsatile flow of a Newtonian blood-analog fluid through a rigid 180° curved artery model. We use a physiologically relevant flow rate and generate results using both fully developed and uniform entrance conditions, the latter motivated by the fact that flow upstream to a curved artery may not be fully developed. Under these two inflow conditions, we characterize the evolution of various vortex pairs and their subsequent effect on several wall shear stress metrics. Supported by GW Center for Biomimetics and Bioinspired Engineering.

  10. Thrombolysis for non-traumatic intra-ventricular hemorrhage in adults: a critical reappraisal.

    Science.gov (United States)

    Starnoni, Daniele; Oddo, Mauro; Maduri, Rodolfo; Messerer, Mahmoud; Daniel, Roy T

    2017-09-01

    Intra-ventricular hemorrhage (IVH) is a critical condition with high rate of morbidity and mortality due to acute hydrocephalus and secondary brain injury. Mechanisms underlying the clinical deterioration are not only related to the appearance of an acute hydrocephalus but also to blood-clot mass effect and the inflammatory effects of blood break-down products which impede local blood flow and exert a direct toxic effect on the peri-ventricular structures leading to chronic hydrocephalus. An effective treatment strategy should aim at IVH fast removal and reduction of blood-clot mass effect. Although external ventricular drainage placement is an intuitive treatment for obstructive hydrocephalus this treatment does not address in total the aforementioned pathophysiological mechanisms underlying secondary brain damage. Intra-ventricular fibrinolysis, with tissue plasminogen activator or urokinase, is a level of evidence B, class IIB treatment which has proved to be beneficial in lowering the mortality rates. Its effectiveness on functional outcome has been assessed on three large meta-analysis and a recent large randomized control trial (CLEAR III). Results from the CLEAR III multicenter trial suggest that a routine extra-ventricular drain, irrigation with alteplase reduced mortality but did not substantially improve functional outcomes compared with irrigation with saline. Protocol-based use of alteplase with extra-ventricular drain seemed safe, therefore such approach may be a potential option in individual cases. Currently no consensus has been reached and extrapolation of data from the literature does not permit to identify a uniform therapeutic approach but merely to outline some rational procedural modalities. Further research and studies are needed to compare the efficacy of the different fibrinolytic agents and protocols on functional outcome.

  11. Successful Right Ventricular Tachycardia Ablation in a Patient with Left Ventricular Non-compaction Cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Shohreh Honarbakhsh, MBBS, BSc, MRCP

    2013-09-01

    Full Text Available We report a case of a 67-year old male with a recent diagnosis of left ventricular noncompaction (LVNC, initially presenting with symptomatic ventricular ectopy and runs of non-sustained ventricular tachycardia (VT. This ventricular arrhythmia originated in a structurally normal right ventricle (RV and was successfully localized and ablated with the aid of the three-dimensional mapping and remote magnetic navigation.

  12. [A case of left ventricular pseudoaneurysm with severe cardiac failure and premature ventricular beats].

    Science.gov (United States)

    Nakmura, M; Kazui, T; Takagi, N; Harada, H; Yokoyama, H; Okamoto, F; Komatsu, S

    1989-10-01

    A surgically successful case of left ventricular pseudoaneurysm 10 years after an acute myocardial infarction was reported. A 63-year-old man had an acute inferior myocardial infarction 10 years ago. Recently congestive heart failure and premature ventricular beats developed. He was diagnosed as a left ventricular pseudoaneurysm by echocardiogram, CT scan, and left ventriculogram. After the operation, the symptoms diminished and improvement of left ventricular function was observed. A brief review of the literature is given.

  13. Towards laboratory detection of topological vortices in superfluid phases of QCD

    Science.gov (United States)

    Das, Arpan; Dave, Shreyansh S.; de, Somnath; Srivastava, Ajit M.

    2017-10-01

    Topological defects arise in a variety of systems, e.g. vortices in superfluid helium to cosmic strings in the early universe. There is an indirect evidence of neutron superfluid vortices from the glitches in pulsars. One also expects that the topological defects may arise in various high baryon density phases of quantum chromodynamics (QCD), e.g. superfluid topological vortices in the color flavor locked (CFL) phase. Though vastly different in energy/length scales, there are universal features in the formation of all these defects. Utilizing this universality, we investigate the possibility of detecting these topological superfluid vortices in laboratory experiments, namely heavy-ion collisions (HICs). Using hydrodynamic simulations, we show that vortices can qualitatively affect the power spectrum of flow fluctuations. This can give an unambiguous signal for superfluid transition resulting in vortices, allowing for the check of defect formation theories in a relativistic quantum field theory system, and the detection of superfluid phases of QCD. Detection of nucleonic superfluid vortices in low energy HICs will give opportunity for laboratory controlled study of their properties, providing crucial inputs for the physics of pulsars.

  14. Motion and interaction of decaying trailing vortices in spanwise shear wind

    Science.gov (United States)

    Liu, C. H.; Lu, T.

    1986-01-01

    A simulation is presented of the drift of trailing vortices in a cross-wind near the ground by an unsteady, two-dimensional, rotational flow field with a concentration of large vorticity in vortical spots (having a finite but small effective size and finite total strength). The problem is analyzed by a combination of the method of matched asymptotic analyses for the decay of the vortical spots and the Euler solution for the unsteady rotational flow. Using the method of averaging, a special numerical method is developed in which the grid size and time step depend only on the length and velocity scales of the background flow and are independent of the effective core size of a vortical spot. The core size can be much smaller than the grid size, whereas the peak velocity in the core is inversely propertional to the spot size. Numerical results are presented to demonstrate the strong interaction between the trajectories of the vortical spots and the change of the vorticity distribution in the background flow field.

  15. Left Ventricular Thrombosis in Ulcerative Colitis

    Directory of Open Access Journals (Sweden)

    Tarek Saleh

    2010-07-01

    Full Text Available Left ventricular thrombi usually occur in the setting of an acute myocardial infarction, left ventricular aneurysm, or dilated cardiomyopathy. In the absence of ventricular wall motion abnormalities, they are rare. This report describes a patient with ulcerative colitis in whom two-dimensional echocardiography revealed a left intraventricular mass. Thrombosis in ulcerative colitis is a serious condition and can occur in a very young population. This case also shows that left ventricular thrombi can occur in the active setting of ulcerative colitis.

  16. Correlation between ankle brachial index, carotid intima media thickness and left ventricular hypertrophy in patients on maintenance hemodialysis

    OpenAIRE

    Hayam A. Hebah; Khaled A. Fouad

    2012-01-01

    Introduction: Left ventricular hypertrophy (LVH) is a major cardiovascular risk factor in patients on maintenance hemodialysis (HD). The aim of our study is to find correlation between ankle brachial index (ABI), carotid intima media thickness (IMT) and left ventricular hypertrophy in this population. Patient and methods: Twenty consecutive patients on maintenance hemodialysis were studied, all clinical data were included and laboratory data recorded, three most recent pre-dialysis blood p...

  17. Polar vortices on Earth and Mars: A comparative study of the climatology and variability from reanalyses.

    Science.gov (United States)

    Mitchell, D M; Montabone, L; Thomson, S; Read, P L

    2015-01-01

    Polar vortices on Mars provide case-studies to aid understanding of geophysical vortex dynamics and may help to resolve long-standing issues regarding polar vortices on Earth. Due to the recent development of the first publicly available Martian reanalysis dataset (MACDA), for the first time we are able to characterise thoroughly the structure and evolution of the Martian polar vortices, and hence perform a systematic comparison with the polar vortices on Earth. The winter atmospheric circulations of the two planets are compared, with a specific focus on the structure and evolution of the polar vortices. The Martian residual meridional overturning circulation is found to be very similar to the stratospheric residual circulation on Earth during winter. While on Earth this residual circulation is very different from the Eulerian circulation, on Mars it is found to be very similar. Unlike on Earth, it is found that the Martian polar vortices are annular, and that the Northern Hemisphere vortex is far stronger than its southern counterpart. While winter hemisphere differences in vortex strength are also reported on Earth, the contrast is not as large. Distinctions between the two planets are also apparent in terms of the climatological vertical structure of the vortices, in that the Martian polar vortices are observed to decrease in size at higher altitudes, whereas on Earth the opposite is observed. Finally, it is found that the Martian vortices are less variable through the winter than on Earth, especially in terms of the vortex geometry. During one particular major regional dust storm on Mars (Martian year 26), an equatorward displacement of the vortex is observed, sharing some qualitative characteristics of sudden stratospheric warmings on Earth.

  18. The left ventricle as a mechanical engine: from Leonardo da Vinci to the echocardiographic assessment of peak power output-to-left ventricular mass.

    Science.gov (United States)

    Dini, Frank L; Guarini, Giacinta; Ballo, Piercarlo; Carluccio, Erberto; Maiello, Maria; Capozza, Paola; Innelli, Pasquale; Rosa, Gian M; Palmiero, Pasquale; Galderisi, Maurizio; Razzolini, Renato; Nodari, Savina

    2013-03-01

    The interpretation of the heart as a mechanical engine dates back to the teachings of Leonardo da Vinci, who was the first to apply the laws of mechanics to the function of the heart. Similar to any mechanical engine, whose performance is proportional to the power generated with respect to weight, the left ventricle can be viewed as a power generator whose performance can be related to left ventricular mass. Stress echocardiography may provide valuable information on the relationship between cardiac performance and recruited left ventricular mass that may be used in distinguishing between adaptive and maladaptive left ventricular remodeling. Peak power output-to-mass, obtained during exercise or pharmacological stress echocardiography, is a measure that reflects the number of watts that are developed by 100 g of left ventricular mass under maximal stimulation. Power output-to-mass may be calculated as left ventricular power output per 100 g of left ventricular mass: 100× left ventricular power output divided by left ventricular mass (W/100 g). A simplified formula to calculate power output-to-mass is as follows: 0.222 × cardiac output (l/min) × mean blood pressure (mmHg)/left ventricular mass (g). When the integrity of myocardial structure is compromised, a mismatch becomes apparent between maximal cardiac power output and left ventricular mass; when this occurs, a reduction of the peak power output-to-mass index is observed.

  19. Characterisation of left ventricular relaxation in the isolated guinea pig heart

    NARCIS (Netherlands)

    Schäfer, S.; Schlack, W.; Kelm, M.; Deussen, A.; Strauer, B. E.

    1996-01-01

    The time constant of left ventricular pressure fall, tau, has frequently been used as a measure of myocardial relaxation in the blood-perfused, ejecting heart. The aim of the present study was to characterise tau in relation to beta-adrenergic activation, coronary perfusion pressure and flow as well

  20. Analysis of Contemporary Methods for Designing Rotary Type Ventricular Assist Devices

    Directory of Open Access Journals (Sweden)

    E. P. Banin

    2015-01-01

    Full Text Available The research object is inlet apparatus of ventricular assist device, namely inlet cannula and straightener.The purpose of the study is to reveal features of blood flow in inlet apparatus of ventricular assist device. The mathematical modeling is carried out by computational fluid dynamics analysis in a stationary setting.The first part of study concerns the analysis of existing approaches to the numerical and experimental studies in designing the ventricular assist devices of rotary type. It reveals the features of each approach for their further application in practice. The article presents an original design of developed hydraulic test bench to verify the results of mathematical modeling. Analysis of foreign authors’ studies showed that there is no enough attention paid to design of the adjacent pump assemblies of ventricular assist device. The second part of study considers direct mathematical modeling of input apparatus of ventricular assist device. The study examined straightener with three or four blades. Mathematical modeling has revealed the presence of potentially dangerous stagnation zones and essential asymmetry of the outlet flow from the input unit. The found features must be taken in consideration in designing the ventricular assist device pumps. In the future we plan to use obtained data to create a parametric model of the rotor and the diffuser considering the abovementioned features.

  1. Comparison of methods for determining absolute left ventricular volumes from radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Warren, S.E.; McKay, R.G.; Aroesty, J.M.; Heller, G.V.; Kolodny, G.M.; Royal, H.D.

    1987-01-01

    Several radionuclide techniques have been used in routine clinical nuclear medicine practice as a means of quantitating left ventricular chamber volumes in man. Despite wide use and availability of the different techniques, however, there has not been a thorough comparison of radionuclide and contrast angiographic measurements performed in the same patients in close temporal proximity. Accordingly, in order to validate traditional methods of ventricular volume measurement, we have performed contrast ventriculography followed immediately (upon return of baseline hemodynamics) by gated radionuclide ventriculography in 34 patients undergoing diagnostic cardiac catheterization. Absolute left ventricular end-diastolic volumes were determined from single-plane, right anterior oblique, end-diastolic contrast silhouettes using a standard area-length method. Radionuclide ventriculographic volumes were determined by three methods: planimetry (32 patients), counts-based (19 patients), and thermodilution stroke volume/radionuclide ejection fraction (32 patients). With planimetry, an area-length method was used in which the modified left anterior oblique left ventricular image was assumed to be a prolate ellipsoid whose volume can be determined by measuring surface area and the ventricular long axis. With the counts-based technique, a blood sample was drawn at the midpoint of the radionuclide ventriculogram acquisition and counted with a gamma camera with appropriate attenuation factor correction. With the thermodilution stroke volume/radionuclide ejection fraction technique, the left ventricular stroke volume was determined by dividing thermodilution cardiac output by the heart rate.

  2. Gyroscopic dynamics of antiferromagnetic vortices on domain boundaries of yttrium orthoferrite

    CERN Document Server

    Chetkin, M V; Shapaeva, T B

    2001-01-01

    It is experimentally established that the magnetic field along the b-axis weakly effects the velocity of the antiferromagnetic vortices on the domain boundary of the yttrium orthoferrite and doesn't explain the existence of the essential gyroscopic force, effecting these vortices. The existence of such a force is caused by the dynamic slope of the magnetic sublattices, proportional to the domain boundary velocity. The dynamics of the antiferromagnetic vortices in the yttrium orthoferrite domain boundaries is gyroscopic and quasirelativistic one with the threshold velocity of 20 km/s, equal to the spin waves velocity on the linear section of their dispersion law

  3. CFD prediction and model experiment on suction vortices in pump sump

    OpenAIRE

    Okamura, Tomoyoshi; Kamemoto, Kyoji; Matsui, Jun

    2007-01-01

    The sump size is being reduced in order to lower the construction costs of urban drainage pump stations in Japan. As a result of such size reductions, undesirable vortices such as air-entrained and submerged vortices are apt to appear in sumps because of the higher flow velocities. The Turbomachinery Society of Japan (TSJ) Standard S002:2005 states that the appearance of such visible vortices is not permissible for conventional sumps, and experiments with scale models usually have been done t...

  4. First measurements of electron vorticity in the foreshock and solar wind

    Energy Technology Data Exchange (ETDEWEB)

    Gurgiolo, C. [Bitterroot Basic Research, Hamilton, MT (United States); Goldstein, M.L.; Vinas, A.F. [NASA Goddard Space Flight Center, Greenbelt, MD (United States). Geospace Science Lab.; Fazakerley, A.N. [University College London (United Kingdom). Mullard Space Science Lab.

    2010-07-01

    We describe the methodology used to set up and compute spatial derivatives of the electron moments using data acquired by the Plasma Electron And Current Experiment (PEACE) from the four Cluster spacecraft. The results are used to investigate electron vorticity in the foreshock. We find that much of the measured vorticity, under nominal conditions, appears to be caused by changes in the flow direction of the return (either reflected or leakage from the magnetosheath) and strahl electron populations as they couple to changes in the magnetic field orientation. This in turn results in deflections in the total bulk velocity producing the measured vorticity. (orig.)

  5. Coronary flow and left ventricular function during environmental stress.

    Science.gov (United States)

    Erickson, H. H.; Adams, J. D.; Stone, H. L.; Sandler, H.

    1972-01-01

    A canine model was used to study the effects of different environmental stresses on the heart and coronary circulation. The heart was surgically instrumented to measure coronary blood flow, left ventricular pressure, and other cardiovascular variables. Coronary flow was recorded by telemetry. Physiologic data were processed and analyzed by analog and digital computers. By these methods the physiologic response to altitude hypoxia, carbon monoxide, hypercapnia, acceleration, exercise, and the interaction of altitude hypoxia and carbon monoxide were described. The effects of some of these stresses on the heart and coronary circulation are discussed.

  6. Recovery of major organ function in patients awaiting heart transplantation with Thoratec ventricular assist devices. Thoratec Ventricular Assist Device Principal Investigators.

    Science.gov (United States)

    Farrar, D J; Hill, J D

    1994-01-01

    The time course of recovery of hepatic and renal function was determined in 193 patients receiving Thoratec ventricular assist devices while awaiting transplantation at 41 hospitals in eight countries. The duration of circulatory support averaged 26 days (maximum 248 days) and the average ventricular assist device blood flow index was 2.7 +/- 0.5 L/min/m2 compared with a preoperative cardiac index of 1.4 +/- 0.7 L/min/m2. Renal and hepatic function improved in most patients in 1 to 3 weeks of support. When comparing patients with the longest durations on the ventricular assist device (60 to 248 days) to patients with the shortest durations (< 7 days), laboratory values were significantly improved: creatinine (-29%, from 1.7 +/- 1.2 to 1.2 +/- 0.5 mg/dl), blood urea nitrogen (-32%, from 37 +/- 27 to 25 +/- 14 mg/dl), serum glutamic-oxaloacetic transaminase (-81%, from 397 +/- 702 to 76 +/- 45 IU) and total bilirubin (-79%, from 7.0 +/- 8.6 to 1.5 +/- 0.7 mg/dl). However, the posttransplantation survival through hospital discharge was not significantly different: 88% (14 of 16) for patients supported for at least 60 days and 86% (43 of 50) for patients who underwent transplantation after only 1 week of support. Therefore renal and hepatic function improve during ventricular assist device support, but the survival rate after transplantation is not related to duration and is comparable to that of conventional heart transplantation for short or long periods of ventricular assist support. Although it is clearly important not to proceed to transplantation in patients with irreversible organ failure who have ventricular assist devices, these data suggest that as long as the patient is on the path to recovery, the outcome is basically the same as for patients who have full recovery of renal and hepatic function.

  7. Spontaneous formation of quantized vortices in Bose-Einstein condensates

    Science.gov (United States)

    Weiler, Chad Nathan

    Phase transitions abound in the physical world, from the subatomic length scales of quark condensation to the decoupling forces in the early universe. In the Bose-Einstein condensation phase transition, a gas of trapped bosonic atoms is cooled to a critical temperature. Below this temperature, a macroscopic number of atoms suddenly starts to occupy a single quantum state; these atoms comprise the Bose-Einstein condensate (BEC). The dynamics of the BEC phase transition are the focus of this dissertation and the experiments described here have provided new information on the details of BEC formation. New theoretical developments are proving to be valuable tools for describing BEC phase transition dynamics and interpreting new experimental results. With their amenability to optical manipulation and probing along with the advent of new microscopic theories, BECs provide an important new avenue for gaining insight into the universal dynamics of phase transitions in general. Spontaneous symmetry breaking in the system's order parameter may be one result of cooling through a phase transition. A potential consequence of this is the spontaneous formation of topological defects, which in a BEC appear as vortices. We experimentally observed and characterized the spontaneous formation of vortices during BEC growth. We attribute vortex creation to coherence length limitations during the initial stages of the phase transition. Parallel to these experimental observations, theory collaborators have used the Stochastic Gross-Pitaevski Equation formalism to simulate the growth of a condensate from a thermal cloud. The experimental and theoretical statistical results of the spontaneous formation of vortex cores during the growth of the condensate are in good quantitative agreement with one another, supporting our understanding of the dynamics of the phase transition. We believe that our results are also qualitatively consistent with the Kibble-Zurek mechanism, a universal model for

  8. Retroflection from slanted coastlines-circumventing the "vorticity paradox"

    Directory of Open Access Journals (Sweden)

    V. Zharkov

    2008-12-01

    Full Text Available The balance of long-shore momentum flux requires that the solution of zonally retroflecting currents involve ring shedding on the western side. An important aspect of the ring dynamics is the ring intensity α (analogous to the Rossby number, which reaches its maximum value of unity when the upstream potential vorticity (PV is zero. Friction leads to a slow-down and a decrease in α. The main difficulty is that the solution of the system of equations for conservation of mass and momentum of zonal currents leads to the conclusion that the ratio (Φ of the mass flux going into the rings and the total incoming mass flux is approximately 4α/(1+2α. This yields the "vorticity paradox" – only relatively weak rings (α≤1/2 could satisfy the necessary condition Φ≤1. Physically, this means, for example, that the momentum-flux of zero PV currents upstream is so high that, no matter how many rings are produced and, no matter what size they are, they cannot compensate for it.

    To avoid this paradox, we develop a nonlinear analytical model of retroflection from a slanted non-zonal coastline. We show that when the slant of coastline (γ exceeds merely 150, Φ does not reach unity regardless of the value of α. Namely, the paradox disappears even for small slants. Our slowly varying nonlinear solution does not only let us circumvent the paradox. It also gives a detailed description of the rings growth rate and the mass flux going into the rings as a function of time. For example, in the case of zero PV and zero thickness of the upper layer along the coastline, the maximal values of Φ can be approximately expressed as, 1.012+0.32exp(−γ/3.41−γ/225. Interestingly, for significant slants γ≥300, the rings reach a terminal size corresponding to a balance between the β-force and both the upstream and downstream momentum fluxes. This terminal size is unrelated to the ultimate

  9. Pulsatile flow in ventricular catheters for hydrocephalus

    Science.gov (United States)

    Giménez, Á.; Galarza, M.; Thomale, U.; Schuhmann, M. U.; Valero, J.; Amigó, J. M.

    2017-05-01

    The obstruction of ventricular catheters (VCs) is a major problem in the standard treatment of hydrocephalus, the flow pattern of the cerebrospinal fluid (CSF) being one important factor thereof. As a first approach to this problem, some of the authors studied previously the CSF flow through VCs under time-independent boundary conditions by means of computational fluid dynamics in three-dimensional models. This allowed us to derive a few basic principles which led to designs with improved flow patterns regarding the obstruction problem. However, the flow of the CSF has actually a pulsatile nature because of the heart beating and blood flow. To address this fact, here we extend our previous computational study to models with oscillatory boundary conditions. The new results will be compared with the results for constant flows and discussed. It turns out that the corrections due to the pulsatility of the CSF are quantitatively small, which reinforces our previous findings and conclusions. This article is part of the themed issue `Mathematical methods in medicine: neuroscience, cardiology and pathology'.

  10. Higher sympathetic nerve activity during ventricular (VVI) than during dual-chamber (DDD) pacing

    Science.gov (United States)

    Taylor, J. A.; Morillo, C. A.; Eckberg, D. L.; Ellenbogen, K. A.

    1996-01-01

    OBJECTIVES: We determined the short-term effects of single-chamber ventricular pacing and dual-chamber atrioventricular (AV) pacing on directly measured sympathetic nerve activity. BACKGROUND: Dual-chamber AV cardiac pacing results in greater cardiac output and lower systemic vascular resistance than does single-chamber ventricular pacing. However, it is unclear whether these hemodynamic advantages result in less sympathetic nervous system outflow. METHODS: In 13 patients with a dual-chamber pacemaker, we recorded the electrocardiogram, noninvasive arterial pressure (Finapres), respiration and muscle sympathetic nerve activity (microneurography) during 3 min of underlying basal heart rate and 3 min of ventricular and AV pacing at rates of 60 and 100 beats/min. RESULTS: Arterial pressure was lowest and muscle sympathetic nerve activity was highest at the underlying basal heart rate. Arterial pressure increased with cardiac pacing and was greater with AV than with ventricular pacing (change in mean blood pressure +/- SE: 10 +/- 3 vs. 2 +/- 2 mm Hg at 60 beats/min; 21 +/- 5 vs. 14 +/- 2 mm Hg at 100 beats/min; p < 0.05). Sympathetic nerve activity decreased with cardiac pacing and the decline was greater with AV than with ventricular pacing (60 beats/min -40 +/- 11% vs. -17 +/- 7%; 100 beats/min -60 +/- 9% vs. -48 +/- 10%; p < 0.05). Although most patients showed a strong inverse relation between arterial pressure and muscle sympathetic nerve activity, three patients with severe left ventricular dysfunction (ejection fraction < or = 30%) showed no relation between arterial pressure and sympathetic activity. CONCLUSIONS: Short-term AV pacing results in lower sympathetic nerve activity and higher arterial pressure than does ventricular pacing, indicating that cardiac pacing mode may influence sympathetic outflow simply through arterial baroreflex mechanisms. We speculate that the greater incidence of adverse outcomes in patients treated with single-chamber ventricular

  11. Verapamil induced ventricular hypertrophy in conscious dogs.

    Science.gov (United States)

    French, W J; Garner, D; Adomian, G E; Averill, W; Laks, M M

    1989-08-01

    Verapamil is used clinically in the treatment of various cardiac diseases including hypertrophic cardiomyopathy. Its long term effects on ventricular mass are not well known. In 11 conscious dogs heart rate, aortic and left ventricular pressures, cardiac output, a methoxamine induced stress ventricular function test and left ventriculography were performed. These variables were measured prior to and following a mean 7.2 month infusion of verapamil at 0.005 or 0.01 mg.kg-1.min-1 using a subcutaneously implanted pump. Resting haemodynamic variables and left ventricular ejection fraction [60(SD 6) v 55(6)%] were unchanged between baseline and chronic verapamil studies, but the slope of the methoxamine induced stress ventricular function test decreased from 3.9(0.8) to 2.1 (1.3). After verapamil was discontinued the mean slope of the stress ventricular function test returned to the baseline 4.0(1.7). Total ventricular weight increased 22% from 176.1(17.5) g.m-2 in controls to 215.6(29.5) g.m-2 (p less than 0.01) in the verapamil animals. The right ventricular weight increased 25% from 46(5.9) to 57.6(9.1) g.m-2 (p less than 0.01); the septum weight increased 26% from 42.5(4.1) to 53.7(7.2) g.m-2 (p less than 0.001); and the left ventricular free wall weight increased 19% from 87.4(9.8) to 103.9(15.7) g.m-2 (p less than 0.01). The increase in ventricular weights was not due to fibrosis or oedema since hydroxyproline contents and wet/dry ratios were not increased. In conclusion, a chronic infusion of verapamil in conscious dogs caused no change in resting haemodynamic variables but produced reversible depression of stress ventricular function and biventricular and septal hypertrophy.

  12. Fluid loading and norepinephrine infusion mask the left ventricular preload decrease induced by pleural effusion

    DEFF Research Database (Denmark)

    Wemmelund, Kristian Borup; Ringgård, Viktor Kromann; Vistisen, Simon Tilma

    2017-01-01

    BACKGROUND: Pleural effusion (PLE) may lead to low blood pressure and reduced cardiac output. Low blood pressure and reduced cardiac output are often treated with fluid loading and vasopressors. This study aimed to determine the impact of fluid loading and norepinephrine infusion on physiologic...... of circulation. All endpoints were assessed with echocardiography and invasive pressure-flow measurements. RESULTS: PLE decreased left ventricular end-diastolic area, mean arterial pressure and cardiac output (p values

  13. Relationship between coronary artery size and ventricular hypertrophy.

    Science.gov (United States)

    Liau, C S; Chen, M F; Chen, W J; Lee, C M; Peng, J Y; Lee, Y T

    1989-02-01

    The relationship between coronary blood flow and ventricular hypertrophy has been studied in animal models. But, this relationship in the human body is scarcely evaluated. In this study we measured coronary arterial sizes by coronary arteriograms and correlated them with ventricular hypertrophy. Patients who underwent cardiac catheterization and coronary arteriography and showed no significant coronary arterial lesions were included in this study. There were 131 patients, 75 men and 56 women, with a mean age of 53 +/- 10 years (S.D.). After evaluation with electrocardiograms, echocardiograms and left ventriculograms these patients were divided into 4 groups: (1) the non-hypertrophy (NVH) group, 50 cases; (2) the left ventricular hypertrophy (LVH) group, 38 cases; (3) the right ventricular hypertrophy (RVH) group, 23 cases; and (4) the biventricular hypertrophy (BVH) group, 20 cases. The proximal portion of the 3 major coronary arteries and the left main stem were measured from coronary arteriograms with the catheter tip as a size reference. The results showed that the left main stem was larger than the 3 major coronary arteries in the NVH, LVH and BVH groups. But in the RVH group, the left main stem was not significantly larger than the right coronary artery. In all 4 groups the left circumflex coronary artery was the smallest while the left anterior descending coronary artery and the right coronary artery were similar in size. Patients with LVH showed dilatation of all 3 left coronary measurements (left main stem, left anterior descending coronary artery and left circumflex coronary artery) as compared with the NVH patients and the RVH patients.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Right Ventricular Outflow Tract Tachycardia with Structural Abnormalities of the Right Ventricle and Left Ventricular Diverticulum

    Directory of Open Access Journals (Sweden)

    Bortolo Martini

    2015-01-01

    Full Text Available A 43-year-old woman presented to the emergency room with a sustained ventricular tachycardia (VT. ECG showed a QRS in left bundle branch block morphology with inferior axis. Echocardiography, ventricular angiography, and cardiac magnetic resonance imaging (CMRI revealed a normal right ventricle and a left ventricular diverticulum. Electrophysiology studies with epicardial voltage mapping identified a large fibrotic area in the inferolateral layer of the right ventricular wall and a small area of fibrotic tissue at the anterior right ventricular outflow tract. VT ablation was successfully performed with combined epicardial and endocardial approaches.

  15. Prognostic significance of left ventricular diastolic dysfunction in patients with left ventricular hypertrophy and systemic hypertension (the LIFE Study)

    DEFF Research Database (Denmark)

    Wachtell, Kristian; Palmieri, Vittorio; Gerdts, Eva

    2010-01-01

    associated with less risk for heart failure. Similarly, normal in-treatment transmitral flow pattern was strongly associated with less risk for heart failure (hazard ratio 0.22, 95% confidence interval 0.05 to 0.98, p = 0.048), even when taking in-treatment left atrial diameter and blood pressure...... was strongly associated with a reduced risk for hospitalization for heart failure.......Patients with hypertension and left ventricular (LV) hypertrophy commonly have impaired diastolic filling. However, it remains unknown whether changes in LV diastolic filling variables are associated with cardiovascular morbidity and mortality. In this study, 778 patients with hypertension...

  16. Impact of the permanent ventricular pacing site on left ventricular function in children: A retrospective multicentre survey

    NARCIS (Netherlands)

    I.E. van Geldorp (Irene); T. Delhaas (Tammo); R.A. Gebauer (Roman); P. Frias (Patrick); M. Tomaske (Maren); M.K. Friedberg (Mark); S. Tisma-Dupanovic (Svjetlana); J. Elders (Jan); A. Früh (Andreas); F. Gabbarini (Fulvio); P. Kubuš (Petr); V. Illikova (Viera); E.C. Tsao (Elisa); A.C. Blank (Andreas Christian); A. Hiippala (Anita); T. Sluysmans (Thierry); P. Karpawich (Peter); S.A. Clur (Sally-Ann); X. Ganame (Xavier); K.K. Collins (Kathryn); G.C. Dann (Greg); J.-B. Thambo (Jean-Benoît); C. Trigo (Conceição); B. Nagel (Bert); J. Papagiannis (John); A. Rackowitz (Annette); J. Marek (Josef); J.-H. Nürnberg (Jan-Hendrik); W.Y. Vanagt (Ward); F.W. Prinzen (Frits); J. Janousek (Jan)

    2011-01-01

    textabstractBackground: Chronic right ventricular (RV) pacing is associated with deleterious effects on cardiac function. Objective In an observational multicentre study in children with isolated atrioventricular (AV) block receiving chronic ventricular pacing, the importance of the ventricular

  17. Vortices generation in the reactive flow on the evaporative surface

    Energy Technology Data Exchange (ETDEWEB)

    Park, Cha Ryeom; Lee, Chang Jin [Konkuk University, Seoul (Korea, Republic of)

    2015-02-15

    Vortices generation and flow dynamics are investigated by a numerical calculation with LES methodology on the evaporative surface including chemical reactions. For simplicity, fuel is radially injected from the surface in order to decouple pyrolysis of solid fuel from the governing equation and consideration of heat transfer balance. Nevertheless its simple treatment of chemical reactions and fuel pyrolysis, numerical results captured very fundamental understandings in terms of averaged temperature, velocity profile, and mixture fraction distribution. Results showed that a well-defined turbulent velocity profile at the inlet becomes twisted and highly wrinkled in the downstream reaching the maximum velocity at far above the surface, where the flame is located. And the thickness of boundary layer increases in the downstream due to the enhanced interaction of axial flow and mass injection from the surface. Also, chemical reaction appears highly active and partially concentrated along the plane where flow condition is in stoichiometric. In particular, flame front locates at the surface where mixture fraction Z equals to 0.07. Flame front severely wrinkles in the downstream by the interaction with turbulences in the flow. Partial reactions on the flame front contribute to produce hot spots periodically in the downstream attaining the max temperature at the center of each spot. This may take the role of additional unsteady heat generations and pressure perturbations in the downstream. Future study will focus on the evolution of hot spots and pressure perturbations in the post chamber of lab scale hybrid rocket motors.

  18. Unsteady flow phenomena associated with leading-edge vortices

    Science.gov (United States)

    Breitsamter, C.

    2008-01-01

    This paper presents selected results from extensive experimental investigations on turbulent flow fields and unsteady surface pressures caused by leading-edge vortices, in particular, for vortex breakdown flow. Such turbulent flows may cause severe dynamic aeroelastic problems like wing and/or fin buffeting on fighter-type aircraft. The wind tunnel models used include a generic delta wing as well as a detailed aircraft configuration of canard-delta wing type. The turbulent flow structures are analyzed by root-mean-square and spectral distributions of velocity and pressure fluctuations. Downstream of bursting local maxima of velocity fluctuations occur in a limited radial range around the vortex center. The corresponding spectra exhibit significant peaks indicating that turbulent kinetic energy is channeled into a narrow band. These quasi-periodic velocity oscillations arise from a helical mode instability of the breakdown flow. Due to vortex bursting there is a characteristic increase in surface pressure fluctuations with increasing angle of attack, especially when the burst location moves closer to the apex. The pressure fluctuations also show dominant frequencies corresponding to those of the velocity fluctuations. Using the measured flow field data, scaling parameters are derived for design purposes. It is shown that a frequency parameter based on the local semi-span and the sinus of angle of attack can be used to estimate the frequencies of dynamic loads evoked by vortex bursting.

  19. Evolution of vorticity and enstrophy in the intracluster medium

    Science.gov (United States)

    Wittor, D.; Jones, T.; Vazza, F.; Brüggen, M.

    2017-11-01

    Turbulence generated by large-scale motions during structure formation affects the evolution of the thermal and non-thermal components of the intracluster medium. As enstrophy is a measure of the magnitude of vorticity, we study the generation and evolution of turbulence by analysing the Lagrangian history of enstrophy. For this purpose, we combine cosmological simulations carried out with the enzo code with our Lagrangian post-processing tool CRaTer. This way we are able to quantify the individual source terms of enstrophy in the course of the accretion of groups on to galaxy clusters. Here, we focus on the redshift range from z = 1 to z = 0. Finally, we measure the rate of dissipation of turbulence and estimate the resulting amplification of intracluster magnetic fields. We find that compressive and baroclinic motions are the main sources of enstrophy, while stretching motions and dissipation affect most of the ensuing enstrophy evolution. The rate of turbulent dissipation is able to sustain the amplification of intracluster magnetic fields to observed levels.

  20. Role of electric discharges in the generation of atmospheric vortices

    Energy Technology Data Exchange (ETDEWEB)

    Sinkevich, O. A., E-mail: oleg.sinkevich@itf.mpei.ac.ru [National Research University “MPEI,” (Russian Federation); Maslov, S. A., E-mail: sergm90@mail.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Gusein-zade, N. G., E-mail: ngus@mail.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2017-02-15

    The existing thermohydrodynamic and hydroelectromagnetic models of tornado are considered. The potentialities of the humid atmosphere as a heat engine generating air vortices are analyzed in detail. The ability of long-term atmospheric electric discharges to form a tornado funnel and create an initial twist of up to 10{sup –3}–10{sup –2} s{sup –1} in it are estimated. The possible effect of a lightning discharge on the initiation and evolution of the tornado is discussed. It is shown that the electric current flowing along the lightning channel can lead to helical instability and generation of a weak primary vortex. The channel formed in the atmosphere by a lightning discharge and the vortex motion of the parent thundercloud can enhance the primary vortex and promote its transformation into a tornado. Possible mechanisms of enhancement of the primary vortex created by a lightning discharge and the possibility of its transformation into a tornado in the postdischarge stage are discussed.

  1. Hawkmoth flight performance in tornado-like whirlwind vortices.

    Science.gov (United States)

    Ortega-Jimenez, Victor Manuel; Mittal, Rajat; Hedrick, Tyson L

    2014-06-01

    Vertical vortex systems such as tornadoes dramatically affect the flight control and stability of aircraft. However, the control implications of smaller scale vertically oriented vortex systems for small fliers such as animals or micro-air vehicles are unknown. Here we examined the flapping kinematics and body dynamics of hawkmoths performing hovering flights (controls) and maintaining position in three different whirlwind intensities with transverse horizontal velocities of 0.7, 0.9 and 1.2 m s(-1), respectively, generated in a vortex chamber. The average and standard deviation of yaw and pitch were respectively increased and reduced in comparison with hovering flights. Average roll orientation was unchanged in whirlwind flights but was more variable from wingbeat to wingbeat than in hovering. Flapping frequency remained unchanged. Wingbeat amplitude was lower and the average stroke plane angle was higher. Asymmetry was found in the angle of attack between right and left wings during both downstroke and upstroke at medium and high vortex intensities. Thus, hawkmoth flight control in tornado-like vortices is achieved by a suite of asymmetric and symmetric changes to wingbeat amplitude, stroke plane angle and principally angle of attack.

  2. Ventricular dilatation in aging and dementia

    NARCIS (Netherlands)

    Palm, Walter Miguel

    2015-01-01

    The general objective of this thesis was to study the causes and consequences of ventricular dilatation in aging and dementia. For this purpose, we used ventricular shape analysis to study potential new MRI markers of cognitive decline in aging, subjective memory complaints, mild cognitive

  3. Arrythmogenic right ventricular dysplasia/cardiomyopathy | Scholtz ...

    African Journals Online (AJOL)

    Arrythmogenic right ventricular dysplasia/cardiomyopathy (ARVD) is a familial cardiomyopathy characterised clinically by right ventricular (RV) dysfunction as well ... can occur and appears to correlate with increased disease severity.3,4 Owing to the complexity of the disease, Task Force Criteria for diagnosis of ARVD were ...

  4. A case of right ventricular myxoma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Goo; Huh, Seung Jae; Han, Man Chung; Choo, Dong Woon [College of Medicine, Seoul National University, Seoul (Korea, Republic of)

    1980-12-15

    A case of right ventricular myxoma is reported with brief review of literatures. The tumor was located in the outflow tract of the right ventricle and prolapsed into the pulmonary artery during the ventricular systole. It was diagnosed by the echocardiography and cineangiography prior to open heart surgery.

  5. Submitral left ventricular aneurysm associated with thrombus ...

    African Journals Online (AJOL)

    Methods: In April 2017, a 25-year-old patient havingsubmitral left ventricular aneurysm with New York Heart Association (NYHA) class IV heart failure and mild left ventricular systolic dysfunctionreceived medical treatment at our institution. She had severe mitral regurgitation and aneurysmal thrombus. The diagnosis was ...

  6. Left ventricular hypertrophy, geometric patterns and clinical ...

    African Journals Online (AJOL)

    Background: Left ventricular hypertrophy can be due to various reasons including hypertension. It constitutes an increased cardiovascular risk. Various left ventricular geometric patterns occur in hypertension and may affect the cardiovascular risk profile of hypertensive subjects. Methods: One hundred and eighty eight ...

  7. Left ventricular hypertrophy as a predictor of cardiovascular risk.

    Science.gov (United States)

    Gosse, Philippe

    2005-04-01

    Left ventricular hypertrophy (LVH) is a potent, independent predictor of cardiovascular events, particularly in hypertension, in which it dramatically increases the risk of stroke, coronary heart disease and heart failure. LVH is predominantly a surrogate marker for the effects of other risk factors integrated over time, but it may also contribute directly to cardiovascular disease through pathological changes in cardiac structure. The influence of blood pressure is central to LVH pathology, with 24-h blood pressure being more predictive of LVH than single clinic measurements. Blood pressure variation throughout the day is also emerging as an important correlate of LVH, and a strong association has been found between the early morning blood pressure rise and increased left ventricular mass. Antihypertensive treatment can reverse LVH, and preliminary studies suggest that this improves cardiovascular outcome and long-term prognosis. Most classes of antihypertensive agent show some effect on LVH regression, with the notable exceptions of minoxidil and hydralazine. However, many of the data regarding LVH regression come from small, poor-quality trials or from meta-analyses of these studies. In the few well-conducted studies that are available, certain classes of antihypertensive drugs are more effective than others. Those that target angiotensin II, such as the angiotensin II receptor blockers, appear to have a specific action on LVH that is independent of blood pressure reduction. Further high-quality studies are needed to define how LVH predicts cardiovascular risk, which agents are most effective at eliciting LVH regression and how such reversal can affect cardiovascular outcome.

  8. Predictors of the left ventricular dysfunction induced by ventricular arrhythmia

    Directory of Open Access Journals (Sweden)

    А. І. Vytryhovskiy

    2016-08-01

    Full Text Available The most powerful predictor of life-threatening arrhythmia risk is a combination of low heart rate variability with low ejection fraction (EF of the left ventricle. Aim. To identify predictors of left ventricle dysfunction which is induced by ventricular arrhythmia. Materials and methods. To diagnose structural changes of left ventricular functional capacity and reserves in patients with previous myocardial infarction and patients with high and very high cardiovascular risk by SCORE scale and for establishment the relationship between morphological heart changes and pathological phenomenon of heart turbulence echocardiography and study of heart rate turbulence variability were performed. 603 patients were selected for the research. All patients were divided into groups: group 1 – patients with coronary heart disease, but without associated risk factors, such as smoking, obesity, metabolic syndrome; group 2 – patients who smoke tobacco more than 2 years (very high cardiovascular risk by scale SCORE; group 3 – patients with metabolic syndrome without coronary heart disease or arterial hypertension (very high cardiovascular risk by scale SCORE. The control group consisted of 149 persons. Results. The feature of structural changes in patients with myocardial infarction and in patients with a high cardiovascular risk by SCORE with heart rate turbulence compared with cases without НRT is considerably thickening of the left interventricular septum in systole. Based on this, it can be argued that the emergence of ventricular arrhythmia and accordingly phenomenon of heart rate turbulence in patients with existing cardiovascular diseases and risk factors has both morphological and functional character. Significant difference of echocardioscopy parameters in patients with postinfarction cardiosclerosis and risk factors by the SCORE system was established by index of intraventricular septum thickness in systole, and in persons with high risk – in

  9. Transport and potential vorticity in the Bay of Bengal during the southwest monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Murty, C.S.; Sarma, Y.V.B.; Rao, D.P.; Sastry, J.S.; Rao, G.R.L.

    In the Bay of Bengal, the water transport and potential vorticity (PV) during the southwest monsoon are examined through the prevailing thermohaline and wind-driven circulation. The Indian Monsoon Current (IMC) and the north flowing Eastern Boundary...

  10. Deterministic creation, pinning, and manipulation of quantized vortices in a Bose-Einstein condensate

    Science.gov (United States)

    Samson, E. C.; Wilson, K. E.; Newman, Z. L.; Anderson, B. P.

    2016-02-01

    We experimentally and numerically demonstrate deterministic creation and manipulation of a pair of oppositely charged singly quantized vortices in a highly oblate Bose-Einstein condensate (BEC). Two identical blue-detuned, focused Gaussian laser beams that pierce the BEC serve as repulsive obstacles for the superfluid atomic gas; by controlling the positions of the beams within the plane of the BEC, superfluid flow is deterministically established around each beam such that two vortices of opposite circulation are generated by the motion of the beams, with each vortex pinned to the in situ position of a laser beam. We study the vortex creation process, and show that the vortices can be moved about within the BEC by translating the positions of the laser beams. This technique can serve as a building block in future experimental techniques to create, on-demand, deterministic arrangements of few or many vortices within a BEC for precise studies of vortex dynamics and vortex interactions.

  11. A quantitative comparison of leading-edge vortices in incompressible and supersonic flows

    Science.gov (United States)

    2002-01-14

    When requiring quantitative data on delta-wing vortices for design purposes, low-speed results have often been extrapolated to configurations intended for supersonic operation. This practice stems from a lack of database owing to difficulties that pl...

  12. Decay of MHD-scale Kelvin-Helmholtz vortices mediated by parasitic electron dynamics.

    Science.gov (United States)

    Nakamura, T K M; Hayashi, D; Fujimoto, M; Shinohara, I

    2004-04-09

    We have simulated nonlinear development of MHD-scale Kelvin-Helmholtz (KH) vortices by a two-dimensional two-fluid system including finite electron inertial effects. In the presence of moderate density jump across a shear layer, in striking contrast to MHD results, MHD KH vortices are found to decay by the time one eddy turnover is completed. The decay is mediated by smaller vortices that appear within the parent vortex and stays effective even when the shear layer width is made larger. It is shown that the smaller vortices are basically of MHD nature while the seeding for these is achieved by the electron inertial effect. Application of the results to the magnetotail boundary layer is discussed.

  13. Dissipation caused by a vorticity field and generation of singularities in Madelung fluid

    Energy Technology Data Exchange (ETDEWEB)

    Caliari, M [Faculty of Mathematical, Physical and Natural Science, University of Verona (Italy); Inverso, G [Elvis Elettronica, Padova (Italy); Morato, L M [Faculty of Mathematical, Physical and Natural Science, University of Verona (Italy)

    2004-07-01

    We consider a generalization of Madelung fluid equations, which was derived in the 1980s by means of a pathwise stochastic calculus of variations with the classical action functional. At variance with the original ones, the new equations allow us to consider velocity fields with vorticity. Such a vorticity causes dissipation of energy and it may concentrate, asymptotically, in the zeros of the density of the fluid. We study, by means of numerical methods, some Cauchy problems for the bidimensional symmetric harmonic oscillator and observe the generation of zeros of the density and concentration of the vorticity close to central lines and cylindrical sheets. Moreover, keeping the same initial data, we perturb the harmonic potential by a term proportional to the density of the fluid, thus obtaining an extension with vorticity of the Gross-Pitaevskii equation, and observe analogous behaviours.

  14. Global vorticity and the definition of the rotation of a deformable earth

    Science.gov (United States)

    Georgiadou, P.; Grafarend, E.

    Within the framework of Newtonian kinematics the local vorticity vector is introduced and averaged with respect to global earth geometry, namely the ellipsoid of revolution. For a deformable body like the earth the global vorticity vector is defined as the earth rotation. A decomposition of the Lagrangian displacement and of the Lagrangian vorticity vector into vector spherical harmonics, namely into spheroidal and toroidal parts, proves that the global vorticity vector only contains toroidal coefficients of degree and order cone (polar motion) and toroidal coefficients of degree one and order zero (length of the day) in the case of an ellipsoidal earth. When an ellipsoid of revolution earth model is assumed, the earth rotation is also slightly dependent on the ellipsoidal flattering and the radial derivative of the spheroidal coefficients of degree two and order one. Finally these coefficients are computed for a Kelvin-type earth model under conservative external forces like tidal gravity.

  15. Potential Vorticity based parameterization for specification of Upper troposphere/lower stratosphere ozone in atmospheric models

    Data.gov (United States)

    U.S. Environmental Protection Agency — Potential Vorticity based parameterization for specification of Upper troposphere/lower stratosphere ozone in atmospheric models - the data set consists of 3D O3...

  16. The Born-Infeld vortices induced from a generalized Higgs mechanism.

    Science.gov (United States)

    Han, Xiaosen

    2016-04-01

    We construct self-dual Born-Infeld vortices induced from a generalized Higgs mechanism. Two specific models of the theory are of focused interest where the Higgs potential is either of a | ϕ | 4 - or | ϕ | 6 -type. For the | ϕ | 4 -model, we obtain a sharp existence and uniqueness theorem for doubly periodic and planar vortices. For doubly periodic solutions, a necessary and sufficient condition for the existence is explicitly derived in terms of the vortex number, the Born-Infeld parameter, and the size of the periodic lattice domain. For the | ϕ | 6 -model, we show that both topological and non-topological vortices are present. This new phenomenon distinguishes the model from the classical Born-Infeld-Higgs theory studied earlier in the literature. A series of results regarding doubly periodic, topological, and non-topological vortices in the | ϕ | 6 -model are also established.

  17. Observation of Half-Quantum Vortices in an Exciton-Polariton Condensate

    National Research Council Canada - National Science Library

    K. G. Lagoudakis; T. Ostatnický; A. V. Kavokin; Y. G. Rubo; R. André; B. Deveaud-Plédran

    2009-01-01

    Singly quantized vortices have already been observed in many systems, including the superfluid helium, Bose-Einstein condensates of dilute atomic gases, and condensates of exciton-polaritons in the solid state...

  18. On periodic geophysical water flows with discontinuous vorticity in the equatorial f-plane approximation

    Science.gov (United States)

    Martin, Calin Iulian

    2017-12-01

    We are concerned here with geophysical water waves arising as the free surface of water flows governed by the f-plane approximation. Allowing for an arbitrary bounded discontinuous vorticity, we prove the existence of steady periodic two-dimensional waves of small amplitude. We illustrate the local bifurcation result by means of an analysis of the dispersion relation for a two-layered fluid consisting of a layer of constant non-zero vorticity γ1 adjacent to the surface situated above another layer of constant non-zero vorticity γ2≠γ1 adjacent to the bed. For certain vorticities γ1,γ2, we also provide estimates for the wave speed c in terms of the speed at the surface of the bifurcation inducing laminar flows. This article is part of the theme issue 'Nonlinear water waves'.

  19. Structure, stability, and evolution of 3D Rossby vortices in protoplanetary disks

    Science.gov (United States)

    Richard, S.; Barge, P.; Le Dizès, S.

    2013-11-01

    Context. Large-scale persistent vortices could play a key role in the evolution of protoplanetary disks, particularly in the dead zone where no turbulence associated with a magnetic field is expected. These vortices are known to form easily in 2D disks via the Rossby wave or the baroclinic instability. In three dimensions, however, their formation and stability is a complex problem and still a matter of debate. Aims: We study the formation of vortices by the Rossby wave instability in a stratified inviscid disk and describe their 3D structure, stability, and long-term evolution. Methods: Numerical simulations were performed using a fully compressible hydrodynamical code based on a second-order finite volume method. We assumed a perfect-gas law and a non-homentropic adiabatic flow. Results: The Rossby wave instability is found to proceed in 3D in a similar way as in 2D. Vortices produced by the instability look like columns of vorticity in the whole disk thickness; the weak vertical motions are related to the weak inclination of the vortex axis that appears during the development of the RWI. Vortices with aspect ratios higher than 6 are unaffected by the elliptical instability. They relax into a quasi-steady columnar structure that survives hundreds of rotations while slowly migrating inward toward the star at a rate that reduces with the vortex aspect ratio. Vortices with a lower aspect ratio are by contrast affected by the elliptic instability. Short aspect ratio vortices (χ < 4) are completely destroyed in a few orbital periods. Vortices with an intermediate aspect ratio (4 < χ < 6) are partially destroyed by the elliptical instability in a region away from the midplane where the disk stratification is sufficiently strong. Conclusions: Elongated Rossby vortices can survive many orbital periods in protoplanetary disks in the form of vorticity columns. They could play a significant role in the evolution of the gas and the gathering of solid particles to form

  20. Giant and thrombosed left ventricular aneurysm.

    Science.gov (United States)

    de Agustin, Jose Alberto; de Diego, Jose Juan Gomez; Marcos-Alberca, Pedro; Rodrigo, Jose Luis; Almeria, Carlos; Mahia, Patricia; Luaces, Maria; Garcia-Fernandez, Miguel Angel; Macaya, Carlos; de Isla, Leopoldo Perez

    2015-07-26

    Left ventricular aneurysms are a frequent complication of acute extensive myocardial infarction and are most commonly located at the ventricular apex. A timely diagnosis is vital due to the serious complications that can occur, including heart failure, thromboembolism, or tachyarrhythmias. We report the case of a 78-year-old male with history of previous anterior myocardial infarction and currently under evaluation by chronic heart failure. Transthoracic echocardiogram revealed a huge thrombosed and calcified anteroapical left ventricular aneurysm. Coronary angiography demonstrated that the left anterior descending artery was chronically occluded, and revealed a big and spherical mass with calcified borders in the left hemithorax. Left ventriculogram confirmed that this spherical mass was a giant calcified left ventricular aneurysm, causing very severe left ventricular systolic dysfunction. The patient underwent cardioverter-defibrillator implantation for primary prevention.

  1. Analytical Derivation of Three Dimensional Vorticity Function for wave breaking in Surf Zone

    OpenAIRE

    Dutta, R.

    2015-01-01

    In this report, Mathematical model for generalized nonlinear three dimensional wave breaking equations was de- veloped analytically using fully nonlinear extended Boussinesq equations to encompass rotational dynamics in wave breaking zone. The three dimensional equations for vorticity distributions are developed from Reynold based stress equations. Vorticity transport equations are also developed for wave breaking zone. This equations are basic model tools for numerical simulation of surf zon...

  2. Direct Assessment of Vorticity Alignment with Local and Nonlocal Strain Rates in Turbulent Flows

    OpenAIRE

    Hamlington, Peter E.; Schumacher, Jörg; Dahm, Werner J. A.

    2008-01-01

    A direct Biot-Savart integration is used to decompose the strain rate into its local and nonlocal constituents, allowing the vorticity alignment with the local and nonlocal strain rate eigenvectors to be investigated. These strain rate tensor constituents are evaluated in a turbulent flow using data from highly-resolved direct numerical simulations. While the vorticity aligns preferentially with the intermediate eigenvector of the \\textit{combined} strain rate, as has been observed previously...

  3. The interplay of curvature and vortices in flow on curved surfaces

    OpenAIRE

    Reuther, Sebastian; Voigt, Axel

    2014-01-01

    Incompressible fluids on curved surfaces are considered with respect to the interplay between topology, geometry and fluid properties using a surface vorticity-stream function formulation, which is solved using parametric finite elements. Motivated by designed examples for superfluids, we consider the influence of a geometric potential on vortices for fluids with finite viscosity and show numerical examples in which a change in the geometry is used to manipulate the flow field.

  4. Dissecting zero modes and bound states on BPS vortices in Ginzburg-Landau superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo, A. Alonso [Departamento de Matematica Aplicada, Universidad de Salamanca,Facultad de Ciencias Agrarias y Ambientales,Av. Filiberto Villalobos 119, E-37008 Salamanca (Spain); Fuertes, W. Garcia [Departamento de Fisica, Universidad de Oviedo, Facultad de Ciencias,Calle Calvo Sotelo s/n, E-33007 Oviedo (Spain); Guilarte, J. Mateos [Departamento de Fisica Fundamental, Universidad de Salamanca, Facultad de Ciencias,Plaza de la Merced, E-37008 Salamanca (Spain)

    2016-05-12

    In this paper the zero modes of fluctuation of cylindrically symmetric self-dual vortices are analyzed and described in full detail. These BPS topological defects arise at the critical point between Type II and Type I superconductors, or, equivalently, when the masses of the Higgs particle and the vector boson in the Abelian Higgs model are equal. In addition, novel bound states of Higss and vector bosons trapped by the self-dual vortices at their core are found and investigated.

  5. Fluctuating pancake vortices revealed by dissipation of the Josephson vortex lattice

    OpenAIRE

    Koshelev, A.E.; Buzdin, A. I.; Kakeya, I.; T. Yamamoto; Kadowaki, K

    2011-01-01

    In strongly anisotropic layered superconductors in tilted magnetic fields, the Josephson vortex lattice coexists with the lattice of pancake vortices. Due to the interaction between them, the dissipation of the Josephson vortex lattice is very sensitive to the presence of the pancake vortices. If the c-axis magnetic field is smaller than the corresponding lower critical field, the pancake stacks are not formed but the individual pancakes may exist in the fluctuational regime either near the s...

  6. Direct simulation of isolated elliptic vortices and of their radiated noise

    Energy Technology Data Exchange (ETDEWEB)

    Barre, Sebastien [Ecole Centrale de Lyon, Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, Ecully Cedex (France); Aircraft and Stores Engineering Technical Directorate, Dassault-Aviation, St Cloud Cedex (France); Bogey, Christophe; Bailly, Christophe [Ecole Centrale de Lyon, Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, Ecully Cedex (France)

    2008-01-15

    The aerodynamic evolution and the acoustic radiation of elliptic vortices with various aspect ratios and moderate Mach numbers are investigated by solving numerically the full compressible Navier-Stokes equations. Three behaviours are observed according to the aspect ratio {sigma}=a/b where a and b are the major and minor semi-axes of the vortices. At the small aspect ratio {sigma}=1.2, the vortex rotates at a constant angular velocity and radiates like a rotating quadrupole. At the moderate aspect ratio {sigma}=5, the vortex is initially unstable. However the growth of instability waves is inhibited by the return to axisymmetry which decreases its aspect ratio. The noise level becomes lower with time and the radiation frequency increases. For vortices with larger aspect ratios {sigma} {>=}6, the return to axisymmetry does not occur quickly enough to stop the growth of instabilities, which splits the vortices. Various mergers are then found to occur. For instance in the case {sigma}=6, several successive switches between an elliptic state and a configuration of two co-rotating vortices are observed. The present results show that the initial value of the aspect ratio yields the relative weight between the return to axisymmetry which stabilizes the vortex and the growth of instabilities which tends to split it. Moreover the noise generated by the vortices is also calculated using the analytical solution derived by Howe (J. Fluid Mech. 71:625-673, 1975) and is compared with the reference solution provided by the direct computation. This solution is found to be valid for {sigma}=1.2. An extended solution is proposed for higher aspect ratios. Finally, the pressure field appears weakly affected by the switches between the two unstable configurations in the case {sigma}=6, which underlines the difficulty to detect the split or the merger of vortices from the radiated pressure. This study also shows that elliptic vortices can be used as a basic configuration of aerodynamic

  7. Experimental investigation of local properties and statistics of optical vortices in random wave fields

    DEFF Research Database (Denmark)

    Wang, W.; Hanson, Steen Grüner; Miyamoto, Y.

    2005-01-01

    We present the first direct experimental evidence of the local properties of optical vortices in a random laser speckle field. We have observed the Berry anisotropy ellipse describing the anisotropic squeezing of phase lines close to vortex cores and quantitatively verified the Dennis angular mom...... momentum rule for its phase. Some statistics associated with vortices, such as density, anisotropy ellipse eccentricity, and its relation to zero crossings of real and imaginary parts of the random field, are also investigated by experiments....

  8. Vorticity visualization: phantom study for a new discriminant parameter in US elastography

    Science.gov (United States)

    Sosa-Cabrera, D.; Rodriguez-Florido, M. A.; Suarez-Santana, E.; Ruiz-Alzola, Juan

    2007-03-01

    Ultrasound elastography measures the elastic properties of soft tissues using ultrasound signals. The elastic problem can be analyzed with tensor signal processing. In this work, we propose a new interpretation of elastography through the deformation tensor and its decomposition into both the strain and vorticity tensors. Vorticity gives information about the rotation of the inclusions that might help in the discrimination between malign and benign tumors without using biopsy. Although clinical validation is needed, synthetic experiments present reliable results.

  9. Rapid normalization of vasculitis-induced left ventricular dysfunction related with multiple cardiac thrombi.

    Science.gov (United States)

    Ikonomidis, Ignatios; Ntai, Konstantina; Parissis, John; Palios, John; Vrettou, Agathi-Rosa; Paraskevaidis, Ioannis; Lekakis, John

    2015-10-01

    We present a young female patient admitted in the emergency department with pulmonary edema, severely impaired left ventricular function, and simultaneous intracardiac thrombi in left and right ventricle as well as in right atrium, at echocardiography. A magnetic resonance tomography showed excess myocardial tissue edema and diffuse gadolinium enhancement. Blood analysis showed an elevated eosinophils count. The patient showed a rapid normalization of left ventricular function as well as resolution of intracardiac thrombi and myocardial tissue edema 3 months after proper treatment with cyclophosphamide and steroids for Churg-Strauss syndrome.

  10. Mechanisms, role of vorticity, and time scales for planar liquid sheet breakup

    Science.gov (United States)

    Zandian, Arash; Sirignano, William; Hussain, Fazle

    2016-11-01

    The 3D, temporal instabilities on a planar liquid sheet are studied using DNS with level-set and VoF surface tracking methods. λ2 contours relate the vorticity to the surface dynamics. The breakup character depends on the Ohnesorge number (Oh). At high Oh , hairpin vortices form on the braid and overlap with the lobe hairpins, thinning the lobes, which puncture creating holes and bridges. The bridges break, creating ligaments that stretch and break into droplets by capillary action. At low Oh , lobe stretching and thinning is hindered by high surface tension and splitting of the original Kelvin-Helmholtz vortex, preventing early hole formation. Corrugations form on the lobe edges, influenced by the split vortices, and stretch to form ligaments. Both mechanisms are present in a transition region that shifts in Oh values based on the liquid/gas density ratio. Different characteristic times exist for the hole formation and the lobe and ligament stretching, related to surface tension and liquid viscosity, respectively. In the transition region, both times are of the same order. Streamwise vorticity triggers the 3D instabilities. Vorticity stretching and baroclinicity dominate, while the spanwise and cross-flow vorticity tilting are less important early in the breakup.

  11. Modulation of leading edge vorticity and aerodynamic forces in flexible flapping wings.

    Science.gov (United States)

    Zhao, Liang; Deng, Xinyan; Sane, Sanjay P

    2011-09-01

    In diverse biological flight systems, the leading edge vortex has been implicated as a flow feature of key importance in the generation of flight forces. Unlike fixed wings, flapping wings can translate at higher angles of attack without stalling because their leading edge vorticity is more stable than the corresponding fixed wing case. Hence, the leading edge vorticity has often been suggested as the primary determinant of the high forces generated by flapping wings. To test this hypothesis, it is necessary to modulate the size and strength of the leading edge vorticity independently of the gross kinematics while simultaneously monitoring the forces generated by the wing. In a recent study, we observed that forces generated by wings with flexible trailing margins showed a direct dependence on the flexural stiffness of the wing. Based on that study, we hypothesized that trailing edge flexion directly influences leading edge vorticity, and thereby the magnitude of aerodynamic forces on the flexible flapping wings. To test this hypothesis, we visualized the flows on wings of varying flexural stiffness using a custom 2D digital particle image velocimetry system, while simultaneously monitoring the magnitude of the aerodynamic forces. Our data show that as flexion decreases, the magnitude of the leading edge vorticity increases and enhances aerodynamic forces, thus confirming that the leading edge vortex is indeed a key feature for aerodynamic force generation in flapping flight. The data shown here thus support the hypothesis that camber influences instantaneous aerodynamic forces through modulation of the leading edge vorticity.

  12. Pinning, flux diodes and ratchets for vortices interacting with conformal pinning arrays

    Science.gov (United States)

    Olson Reichhardt, C. J.; Wang, Y. L.; Xiao, Z. L.; Kwok, W. K.; Ray, D.; Reichhardt, C.; Jankó, B.

    2017-02-01

    A conformal pinning array can be created by conformally transforming a uniform triangular pinning lattice to produce a new structure in which the six-fold ordering of the original lattice is conserved but where there is a spatial gradient in the density of pinning sites. Here we examine several aspects of vortices interacting with conformal pinning arrays and how they can be used to create a flux flow diode effect for driving vortices in different directions across the arrays. Under the application of an ac drive, a pronounced vortex ratchet effect occurs where the vortices flow in the easy direction of the array asymmetry. When the ac drive is applied perpendicular to the asymmetry direction of the array, it is possible to realize a transverse vortex ratchet effect where there is a generation of a dc flow of vortices perpendicular to the ac drive due to the creation of a noise correlation ratchet by the plastic motion of the vortices. We also examine vortex transport in experiments and compare the pinning effectiveness of conformal arrays to uniform triangular pinning arrays. We find that a triangular array generally pins the vortices more effectively at the first matching field and below, while the conformal array is more effective at higher fields where interstitial vortex flow occurs.

  13. Nonlinear axisymmetric and three-dimensional vorticity dynamics in a swirling jet model

    Science.gov (United States)

    Martin, J. E.; Meiburg, E.

    1996-01-01

    The mechanisms of vorticity concentration, reorientation, and stretching are investigated in a simplified swirling jet model, consisting of a line vortex along the jet axis surrounded by a jet shear layer with both azimuthal and streamwise vorticity. Inviscid three-dimensional vortex dynamics simulations demonstrate the nonlinear interaction and competition between a centrifugal instability and Kelvin-Helmholtz instabilities feeding on both components of the base flow vorticity. Under axisymmetric flow conditions, it is found that the swirl leads to the emergence of counterrotating vortex rings, whose circulation, in the absence of viscosity, can grow without bounds. Scaling laws are provided for the growth of these rings, which trigger a pinch-off mechanism resulting in a strong decrease of the local jet diameter. In the presence of an azimuthal disturbance, the nonlinear evolution of the flow depends strongly on the initial ratio of the azimuthal and axisymmetric perturbation amplitudes. The long term dynamics of the jet can be dominated by counterrotating vortex rings connected by braid vortices, by like-signed rings and streamwise braid vortices, or by wavy streamwise vortices alone.

  14. Observations of Electron Vorticity in the Inner Plasmasheet and Its Relationship to Reconnection

    Science.gov (United States)

    Gurgiolo, Chris A.; Goldstein, Melvyn L.; Matthaeus, William H.; Vinas, Adolfo -F.

    2011-01-01

    Spatial derivatives of the electron moments can be estimated using data from the four Cluster spacecraft. Using spatial derivatives of the velocity we have computed the vorticity in the plasmasheet for several crossings. What we have found is that vorticity appears to be a common feature in the inner plasmasheet. We will show a number of examples. In at least some of the observations the vorticity is well correlated with the passage of Cluster through the ion diffusion region of known reconnection events. That most of the vorticity events observed are reconnection related cannot be dismissed and in fact observations of vorticity may provide a means to locate times when the Cluster spacecraft are magnetically connected to regions where reconnection is taking place. Understanding the role and source of the vorticity should advance our understanding of the dissipation of the turbulence associated with reconnection. In the course of the presentation we will also touch on the methods used to estimate the spatial derivatives as well as the limitations and assumptions involved.

  15. On the odd and even secondary instabilities of Görtler vortices

    Science.gov (United States)

    Souza, Leandro F.

    2017-08-01

    Boundary layer flows over concave wall can be unstable to disturbances giving rise to streamwise counter-rotating vortices known as Görtler vortices. These vortices in its nonlinear form are responsible for a strong distortion of the streamwise velocity profiles in the wall-normal and spanwise directions. The resulting inflectional velocity profiles are unstable to unsteady disturbances. These disturbances are called secondary instabilities and can develop into horseshoe vortices or a sinuous motion of the Görtler vortices. These types of secondary instabilities are known as even (varicose) and odd (sinuous) modes, respectively. Although many studies focused this subject, it has not been stated which mode dominates the transition process. In the present study the secondary instability of Görtler flow is investigated using high-order spatial numerical simulation. Multi-frequency unsteady disturbances are introduced with the same spanwise wavelength as the Görtler vortices, but different spanwise phases. Three different spanwise phases are used and the effect on the secondary instability is analyzed. Both, even and odd secondary instabilities are observed, according to the relative spanwise position of the unsteady disturbances. The growth analysis for each secondary crossplane instability mode is made using a temporal Fourier analysis and the physics is explored with the aid of the flow structures visualization. The results introducing disturbances that give rise to odd and even modes simultaneously show that, for the spanwise wavelength analyzed, the odd modes grow first and dominate the transition process.

  16. Flow-pattern analysis in open and closed square ducts: A comparative investigation of corner vortices

    Science.gov (United States)

    Kriegseis, Jochen; Vaas, Markus; Frohnapfel, Bettina

    2013-11-01

    In the present study secondary flows in straight square ducts are investigated experimentally for open and closed geometries. The flow of the closed square duct typically consists of a set of eight equal-sized counter-rotating vortices. In contrast, the flow in an open flume of (identical) square geometry is considered, where the development of secondary vortices is strongly affected by the presence of the free surface. Stereo Particle Image Velocimetry (SPIV) experiments have been performed so as to measure the flow in both geometries for varying Reynolds numbers. From the resulting 2D3C velocity information secondary vortices (superimposed onto the mean primary flow) are identified. As expected, the upper bisectors' flow topology differs significantly between open and closed ducts, where typical inner and outer vortices are identified from the open-duct data. Interestingly, the secondary vortices of the lower bisectors of both duct flows reveal a similar topology. In order to study this seeming similarit more rigorously, a modal analysis of the respective flow data is performed by means of proper orthogonal decomposition (POD). As such, similarities and limitations of the comparability of the respective corner vortices are uncovered and discussed as function of Reynolds number. J. Kriegseis acknowledges financial support by the German Academic Exchange Service (DAAD)

  17. Upwelling Response to Hurricane Isaac in Geostrophic Oceanic Vortices

    Science.gov (United States)

    Jaimes, B.; Shay, L. K.; Brewster, J. K.; Schuster, R.

    2013-05-01

    As a tropical cyclone (TC) moves over the ocean, the cyclonic curl of the wind stress produces a region of upwelling waters under the TC center that is compensated by downwelling waters at regions outside the center. Direct measurements conducted during hurricane Rita and recent numerical studies indicate that this is not necessarily the case when TCs move over geostrophic oceanic features, where its background relative vorticity impacts wind-driven horizontal current divergence and the upwelling velocity. Modulation of the upwelling response in these energetic oceanic regimes impacts vertical mixing across the oceanic mixed layer base, air-sea fluxes into the atmosphere, and ultimately storm intensity. As part of NOAA Intensity Forecasting Experiment, an experiment was conducted during the passage of TC Isaac over the energetic geostrophic eddy field in the Gulf of Mexico in August 2012. Expendable bathythermographs, current profilers, and conductivity-temperature-depth probes were deployed in Isaac from NOAA WP-3D aircraft during four in-storm flights to measure oceanic variability and its impact on TC-driven upwelling and surface fluxes of heat and momentum. During intensification to hurricane, the cyclonic curl of the wind stress of Isaac extended over a region of more than 300 km in diameter (4 to 5 times the radius of maximum winds). Isaac's center moved over a cold cyclonic feature, while its right and left sides moved over warm anticyclones. Contrasting upwelling and downwelling regimes developed inside the region of cyclonic curl of the wind stress. Both positive (upwelling) and negative (downwelling) vertical displacements of 40 and 60 m, respectively, were measured inside the region of cyclonic curl of the wind stress, which are between 3 to 4 times larger than predicted vertical displacements for a quiescent ocean based on scaling arguments. Oceanic mixed layer (OML) currents of 0.2 to 0.7 m s-1 were measured, which are about 50% smaller than the

  18. Downstream evolution of unconfined vortices: mechanical and thermal aspects

    Science.gov (United States)

    Pérez-Saborid, M.; Herrada, M. A.; Gómez-Barea, A.; Barrero, A.

    2002-11-01

    We present a numerical study of the downstream evolution (mechanical and thermal) of vortex-jet cores whose velocity and temperature fields far from the axis match a family of inviscid and non-conducting vortices. The far-velocity field is rotational, except for a particular case which corresponds to the well-known Long's vortex. The evolution of the vortex core depends on both the conditions at a certain upstream station, characterized by the dimensionless value of the velocity at the axis, and a dimensionless swirling parameter L defined as the ratio of the values of the azimuthal and axial velocities outside the vortex core. This numerical study, based on the quasi-cylindrical approximation (QC) of the Navier Stokes equations, determines the conditions under which the vortex evolution proceeds smoothly, eventually reaching an asymptotic self-similar behaviour as described in the literature (Fernández-Feria, Fernández de la Mora & Barrero 1995; Herrada, Pérez-Saborid & Barrero 1999), or breaks in a non-slender solution (vortex breakdown). In particular, the critical value L = Lb(a) beyond which vortex breakdown occurs downstream is a function of a dimensionless parameter a characterizing the axial momentum of the vortex jet at an initial upstream station. It is found numerically that for very large values of a this vortex breakdown criterion tends to an asymptote which is precisely the value L = L* predicted by the self-similar analysis, and beyond which a self-similar structure of the vortex core does not exist. In addition, the computation of the total temperature field provides useful information on the physical mechanisms responsible for the thermal separation phenomenon observed in Ranque Hilsch tubes and other swirling jet devices. In particular, the mechanical work of viscous forces which gives rise to an intense loss of kinetic energy during the initial stages of the evolution has been identified as the physical mechanism responsible for thermal

  19. Thermal Separation in a Family of Self-Similar Vortices

    Science.gov (United States)

    Herrada, M. A.; Perez-Saborid, M.; Barrero, A.

    1997-11-01

    Swirling flows have a very wide range of applications and exhibit a variety of interesting features. One of them is the phenomenon of thermal separation, the so-called Ranque-Hilsch effect, observed under certain conditions in swirling gas jets. The cold gas stream is confined near the jet axis while the hotter one locates at the periphery. The low efficiency of the existing Ranque-Hilsch tubes is probably due to an incomplete understanding of the basic fluid mechanics involved in the thermal separation effect. To gain insight into the phenomenon under consideration, we have analyzed the near axis boundary layer of a gas jet driven by a class of self-similar inviscid vortical incompressible flow which satisfies the Euler equations and whose velocity field, in cylindrical coordinates, behaves near the axis as v = Wo r^m-2(e_z+L e_θ), where Wo and L are arbitrary positive constants and m is any real number such as 1<= m<2. In our analysis, we have considered low Mach number flows with small relative variations in the gas temperature, so that the mechanical and thermal problems can be solved separately. For a given value of m, the difference between the maximum and minimum stagnation temperature of the flow (thermal separation) can be plotted as a function of the Squire parameter L which is directly related to the swirl strength. We found that there is an optimum value L_op for which thermal separation reaches a sharp maximum so that small differences in the value of L-L_op drastically reduces the thermal separation.

  20. Turbulence and vorticity in Galaxy clusters generated by structure formation

    Science.gov (United States)

    Vazza, F.; Jones, T. W.; Brüggen, M.; Brunetti, G.; Gheller, C.; Porter, D.; Ryu, D.

    2017-01-01

    Turbulence is a key ingredient for the evolution of the intracluster medium, whose properties can be predicted with high-resolution numerical simulations. We present initial results on the generation of solenoidal and compressive turbulence in the intracluster medium during the formation of a small-size cluster using highly resolved, non-radiative cosmological simulations, with a refined monitoring in time. In this first of a series of papers, we closely look at one simulated cluster whose formation was distinguished by a merger around z ˜ 0.3. We separate laminar gas motions, turbulence and shocks with dedicated filtering strategies and distinguish the solenoidal and compressive components of the gas flows using Hodge-Helmholtz decomposition. Solenoidal turbulence dominates the dissipation of turbulent motions (˜95 per cent) in the central cluster volume at all epochs. The dissipation via compressive modes is found to be more important (˜30 per cent of the total) only at large radii (≥0.5rvir) and close to merger events. We show that enstrophy (vorticity squared) is good proxy of solenoidal turbulence. All terms ruling the evolution of enstrophy (I.e. baroclinic, compressive, stretching and advective terms) are found to be significant, but in amounts that vary with time and location. Two important trends for the growth of enstrophy in our simulation are identified: first, enstrophy is continuously accreted into the cluster from the outside, and most of that accreted enstrophy is generated near the outer accretion shocks by baroclinic and compressive processes. Secondly, in the cluster interior vortex, stretching is dominant, although the other terms also contribute substantially.

  1. Dynamics of vortices and active matter on structured substrates

    Science.gov (United States)

    Ray, Dipanjan

    This work investigates various physical problems under the general category of particles being driven over an ordered or disordered substrate. The general problem has clear applications to frictional phenomena, ranging from stick-slip motion to earthquakes; here we consider more novel scenarios taken from the fields of superconductivity and biophysics. The "conformal crystal" structure is investigated in the context of superconducting vortex pinning. This 2D structure is generated mathematically by a conformal transformation of a regular hexagonal lattice, and possesses local hexagonal ordering, but globally features a density gradient in one dimension and an arching structure in the other dimension. A vortex pinning array based on this structure is shown to have superior magnetization and transport properties as compared to other previously considered pinning arrays, and is used to construct a highly effective ratchet for vortices. An Archimedean pinning structure, with two characteristic length scales, is also considered, as an intermediate case between periodic pinning with a single length scale, and conformal pinning with a continuum of scales due to the density gradient. Magnetization studies reveal a variety of novel vortex states at integer and fractional matching fields, which are not present in either periodic or conformal pinning. Finally, an nanoassembly experiment is simulated where the particles affect the substrate, as opposed to the more common reverse scenario which underlies the other topics in this work. The energy of run-and-tumble active matter particles (such as E. coli bacteria undergoing chemotactic motion) is harnessed to push together two movable walls arranged in a Casimir geometry.

  2. Gaps and rings carved by vortices in protoplanetary dust

    Science.gov (United States)

    Barge, Pierre; Ricci, Luca; Carilli, Christopher Luke; Previn-Ratnasingam, Rathish

    2017-09-01

    Context. Large-scale vortices in protoplanetary disks are thought to form and survive for long periods of time. Hence, they can significantly change the global disk evolution and particularly the distribution of the solid particles embedded in the gas, possibly explaining asymmetries and dust concentrations recently observed at submillimeter and millimeter wavelengths. Aims: We investigate the spatial distribution of dust grains using a simple model of protoplanetary disk hosted by a giant gaseous vortex. We explore the dependence of the results on grain size and deduce possible consequences and predictions for observations of the dust thermal emission at submillimeter and millimeter wavelengths. Methods: Global 2D simulations with a bi-fluid code are used to follow the evolution of a single population of solid particles aerodynamically coupled to the gas. Possible observational signatures of the dust thermal emission are obtained using simulators of ALMA and Nest Generation Very Large Array (ngVLA) observations. Results: We find that a giant vortex not only captures dust grains with Stokes number St< 1 but can also affect the distribution of larger grains (with St 1) carving a gap associated with a ring composed of incompletely trapped particles. The results are presented for different particle sizes and associated with their possible signatures in disk observations. Conclusions: Gap clearing in the dust spatial distribution could be due to the interaction with a giant gaseous vortex and their associated spiral waves without the gravitational assistance of a planet. Hence, strong dust concentrations at short sub-mm wavelengths associated with a gap and an irregular ring at longer mm and cm wavelengths could indicate the presence of an unseen gaseous vortex.

  3. Formation and characterization of the vortices generated by a DBD plasma actuator in burst mode

    Science.gov (United States)

    Mishra, Bal Krishan; Panigrahi, P. K.

    2017-02-01

    The present study reports the formation and evolution characteristics of the continuously generated vortical structure and resulting flow field in quiescent air induced by a dielectric-barrier-discharge (DBD) plasma actuator in burst mode operation. A starting vortex is formed during the initial actuation period, which disappears after a small time interval for continuous mode operation of the DBD plasma actuator. A burst input signal to the actuator generates a train of self-similar vortices. The behaviour of vortices and the average flow field induced by the actuator has been studied using high speed schlieren visualization and particle image velocimetry technique for different actuation amplitude and duty cycle parameters. These repeating vortices travel faster than the starting vortex, and the vortex core velocity of these repeating vortices increases with increase in duty cycle parameter. Fuller u-velocity profile, higher v-velocity near the edge of the outer shear layer region, and higher growth of the wall jet thickness is observed due to enhanced entrainment by repeating vortices for burst mode operation. The repeating vortices travel at an angle of 21° relative to the wall surface for duty cycle parameter of 90.9% in comparison to 31° for the starting vortex. Self-similarity of the velocity profile is delayed in the streamwise direction for burst mode operation in comparison to that for the continuous mode of operation. This can be attributed to delay in attaining the maximum velocity of the wall jet profile and presence of coherent structures for the burst mode operation. The non-dimensional vortex core location and size for repeating vortices follow power law fit similar to the starting vortex with difference in value of the power law exponent. The phase difference between the input voltage and current drawn is in the range of π/12 to π/9 (in radians) for both continuous and burst mode operation indicating identical electrical behaviour of the

  4. Non-Newtonian perspectives on pulsatile blood-analog flows in a 180° curved artery model

    Science.gov (United States)

    van Wyk, Stevin; Prahl Wittberg, Lisa; Bulusu, Kartik V.; Fuchs, Laszlo; Plesniak, Michael W.

    2015-07-01

    Complex, unsteady fluid flow phenomena in the arteries arise due to the pulsations of the heart that intermittently pumps the blood to the extremities of the body. The many different flow waveform variations observed throughout the arterial network are a result of this process and a function of the vessel properties. Large scale secondary flow structures are generated throughout the aortic arch and larger branches of the arteries. An experimental 180° curved artery test section with physiological inflow conditions was used to validate the computational methods implemented in this study. Good agreement of the secondary flow structures is obtained between experimental and numerical studies of a Newtonian blood-analog fluid under steady-state and pulsatile, carotid artery flow rate waveforms. Multiple vortical structures, some of opposite rotational sense to Dean vortices, similar to Lyne-type vortices, were observed to form during the systolic portion of the pulse. Computational tools were used to assess the effect of blood-analog fluid rheology (i.e., Newtonian versus non-Newtonian). It is demonstrated that non-Newtonian, blood-analog fluid rheology results in shear layer instabilities that alter the formation of vortical structures during the systolic deceleration and onwards during diastole. Additional vortices not observed in the Newtonian cases appear at the inside and outside of the bend at various times during the pulsation. The influence of blood-analog shear-thinning viscosity decreases mean pressure losses in contrast to the Newtonian blood analog fluid.

  5. Blood Disorders

    Science.gov (United States)

    ... blood cells, white blood cells and platelets. Blood disorders affect one or more parts of the blood ... They can be acute or chronic. Many blood disorders are inherited. Other causes include other diseases, side ...

  6. β1-Adrenoceptor blocker aggravated ventricular arrhythmia.

    Science.gov (United States)

    Wang, Yan; Patel, Dimpi; Wang, Dao Wu; Yan, Jiang Tao; Hsia, Henry H; Liu, Hao; Zhao, Chun Xia; Zuo, Hou Juan; Wang, Dao Wen

    2013-11-01

    To assess the impact of β1 -adrenoceptor blockers (β1 -blocker) and isoprenaline on the incidence of idiopathic repetitive ventricular arrhythmia that apparently decreases with preprocedural anxiety. From January 2010 to July 2012, six patients were identified who had idiopathic ventricular arrhythmias that apparently decreased (by greater than 90%) with preprocedural anxiety. The number of ectopic ventricular beats per hour (VPH) was calculated from Holter or telemetry monitoring to assess the ectopic burden. The mean VPH of 24 hours from Holter before admission (VPH-m) was used as baseline (100%) for normalization. β1 -Blockers, isoprenaline, and/or aminophylline were administrated successively on the ward and catheter lab to evaluate their effects on the ventricular arrhythmias. Among 97 consecutive patients with idiopathic ventricular arrhythmias, six had reduction in normalized VPHs in the hour before the scheduled procedure time from (104.6 ± 4.6%) to (2.8 ± 1.6%) possibly due to preprocedural anxiety (P < 0.05), then increased to (97.9 ± 9.7%) during β1 -blocker administration (P < 0.05), then quickly reduced to (1.6 ± 1.0%) during subsequent isoprenaline infusion. Repeated β1 -blocker quickly counteracted the inhibitory effect of isoprenaline, and VPHs increased to (120.9 ± 2.4%) from (1.6 ± 1.0%; P < 0.05). Isoprenaline and β1 -blocker showed similar effects on the arrhythmias in catheter lab. In some patients with structurally normal heart and ventricular arrhythmias there is a marked reduction of arrhythmias associated with preprocedural anxiety. These patients exhibit a reproducible sequence of β1 -blocker aggravation and catecholamine inhibition of ventricular arrhythmias, including both repetitive ventricular premature beats and monomorphic ventricular tachycardia. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.

  7. Increased left ventricular mass in normotensive type 1 diabetic patients with diabetic nephropathy

    DEFF Research Database (Denmark)

    Sato, A; Tarnow, L; Parving, H H

    1998-01-01

    OBJECTIVE: Diabetic nephropathy increases the risk of premature cardiovascular disease and sudden death, particularly in type 1 diabetic patients. One possible mechanism for this risk may be left ventricular hypertrophy. In our study, we aimed to evaluate left ventricular structure and function...... in normotensive type 1 diabetic patients with and without nephropathy. RESEARCH DESIGN AND METHODS: M-mode and Doppler echocardiography was performed in 17 type 1 diabetic patients with nephropathy (albuminuria [median (range)], 345 (135-2,846) mg/24 h) and compared with 34 normotensive, normoalbuminuric (10 [3......-30] mg/24 h) type 1 diabetic patients matched for arterial blood pressure (mean +/- SD) ([134/77] +/- [13/7] vs. [129/78] +/- [12/7] mmHg), age (40 +/- 11 vs. 42 +/- 10 years), duration of diabetes (28 +/- 7 vs. 28 +/- 6 years), and BMI (24.2 +/- 4.2 vs. 24.6 +/- 2.4 kg/m2). RESULTS: Left ventricular...

  8. Prognostic significance of left ventricular diastolic dysfunction in patients with left ventricular hypertrophy and systemic hypertension (the LIFE Study)

    DEFF Research Database (Denmark)

    Wachtell, Kristian; Palmieri, Vittorio; Gerdts, Eva

    2010-01-01

    valve flow pattern, this was not associated with reduced cardiovascular morbidity and mortality when adjusting for blood pressure, left atrial diameter, LV mass index, and treatment in time-varying Cox analyses. In contrast, lower in-treatment E/A ratios and shorter mitral valve deceleration times were...... associated with less risk for heart failure. Similarly, normal in-treatment transmitral flow pattern was strongly associated with less risk for heart failure (hazard ratio 0.22, 95% confidence interval 0.05 to 0.98, p = 0.048), even when taking in-treatment left atrial diameter and blood pressure......Patients with hypertension and left ventricular (LV) hypertrophy commonly have impaired diastolic filling. However, it remains unknown whether changes in LV diastolic filling variables are associated with cardiovascular morbidity and mortality. In this study, 778 patients with hypertension...

  9. Remodelado ventricular y cirugía

    Directory of Open Access Journals (Sweden)

    Ignacio Moriones

    2008-01-01

    Se han diseñado anillos mitrales como el de Carpentier- McCarthy-Adams (IMR ETlogix™ para pacientes isquémicos, o el Edwards-Geoform™ en miocardiopatías. La asistencia ventricular puede conseguir en determinados casos recuperación permanente del volumen de la cavidad y función ventricular, particularmente en miocarditis y determinadas miocardiopatías. Paralelamente, se han iniciado experiencias con el sistema de contención CorCap o el sistema Myosplint. Finalmente, la actuación sobre las valvulopatías y la revascularización favorecen la restauración ventricular.

  10. An Unusual Left Ventricular Apical Mass

    Science.gov (United States)

    Cavallero, Erika; Curzi, Mirko; Cioccarelli, Sara Anna; Papalia, Giulio; Ornaghi, Diego; Bragato, Renato Maria

    2014-01-01

    Left ventricular apical masses constitute a rare finding. Imaging properties together with the clinical history of the patient usually allow an etiologic definition. We report a challenging case of an ambiguous left ventricular apical mass of uncertain nature till histological examination. Points of interest were singular clinical history and echocardiographic findings, although not conclusive in hypothesis generating. Furthermore to the best of our knowledge, this is one of the rare attempt to excise a deep left ventricular mass with a mini-invasive surgical approach. PMID:28465915

  11. Hemoglobin A1c and arterial and ventricular stiffness in older adults.

    Directory of Open Access Journals (Sweden)

    Susan J Zieman

    Full Text Available Arterial and ventricular stiffening are characteristics of diabetes and aging which confer significant morbidity and mortality; advanced glycation endproducts (AGE are implicated in this stiffening pathophysiology. We examined the association between HbA(1c, an AGE, with arterial and ventricular stiffness measures in older individuals without diabetes.Baseline HbA(1c was measured in 830 participants free of diabetes defined by fasting glucose or medication use in the Cardiovascular Health Study, a population-based cohort study of adults aged ≥ 65 years. We performed cross-sectional analyses using baseline exam data including echocardiography, ankle and brachial blood pressure measurement, and carotid ultrasonography. We examined the adjusted associations between HbA(1c and multiple arterial and ventricular stiffness measures by linear regression models and compared these results to the association of fasting glucose (FG with like measures.HbA(1c was correlated with fasting and 2-hour postload glucose levels (r = 0.21; p<0.001 for both and positively associated with greater body-mass index and black race. In adjusted models, HbA(1c was not associated with any measure of arterial or ventricular stiffness, including pulse pressure (PP, carotid intima-media thickness, ankle-brachial index, end-arterial elastance, or left ventricular mass (LVM. FG levels were positively associated with systolic, diastolic and PP and LVM.In this sample of older adults without diabetes, HbA(1c was not associated with arterial or ventricular stiffness measures, whereas FG levels were. The role of AGE in arterial and ventricular stiffness in older adults may be better assessed using alternate AGE markers.

  12. Role of signal-averaged electrocardiography and ventricular late potentials in patients with chronic obstructive pulmonary disease.

    Science.gov (United States)

    Buzea, C A; Dan, G A; Dan, Anca Rodica; Delcea, Caterina; Balea, M I; Gologanu, Daniela Stefana; Dobranici, Mihaela; Popescu, Raluca Alexandra

    2015-01-01

    Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiac arrhythmias. Ventricular late potentials (VLP) on signal-averaged electrocardiography (SAECG) are associated with an increased risk for malignant ventricular arrhythmias. Our aim is to investigate the modifications of SAECG parameters and the presence of VLP as possible indicators of proarrhythmic substrate in patients with COPD. We prospectively enrolled 41 consecutive patients in the COPD group and 63 patients without any history of pulmonary disease, matched for age and hypertension history, in the control group. Pulmonary function tests, arterial blood gases, echocardiography, 24-hour Holter monitoring and SAECG were performed. We measured total filtered QRS duration (QRSf), duration of high frequency, low-amplitude signals electrocardiography and ventricular late potentials analysis have little value in risk stratification for ventricular arrhythmias.

  13. Influence of long-term arotinolol treatment on myocardial mechanics and ventricular myosin isoenzymes in spontaneously hypertensive rats.

    Science.gov (United States)

    Takeda, N; Ohkubo, T; Iwai, T; Tanamura, A; Nagano, M

    1990-01-01

    Alterations in myocardial mechanics and left ventricular myosin isoenzymes by long-term treatment of hypertension with arotinolol were examined in spontaneously hypertensive rats. Approximately 20 mg/kg/day arotinolol was administered to 22-week-old male spontaneously hypertensive rats for 8-10 weeks. There was no significant difference in systolic blood pressure between arotinolol-treated and untreated rats. However, ventricular weight tended to decrease in the arotinolol-treated group, although not significantly. There were no significant differences in isometric developed tension and dT/dtmax of isolated left ventricular papillary muscles between the arotinolol-treated and untreated groups. The left ventricular myosin isoenzyme pattern, on the other hand, obtained by pyrophosphate gel electrophoresis, showed a significant shift toward VM-1 as a result of long-term arotinolol treatment.

  14. Incidence of ventricular arrhythmias, brady-arrhythmias and sudden ...

    African Journals Online (AJOL)

    Ventricular arrhythmias (VAS), Including ventricular tachycardia (VT), ventricular fibrillation (VF) and Brady-arrhythmias, are life-threatening complications of acute myocardial infarction (MI). Objective: To study the incidence of ventricular arrhythmias, brady-arrhythmias and Sudden Cardiac Death (SCD) in Sudanese ...

  15. Effects of wing locations on wing rock induced by forebody vortices

    Directory of Open Access Journals (Sweden)

    Ma Baofeng

    2016-10-01

    Full Text Available Previous studies have shown that asymmetric vortex wakes over slender bodies exhibit a multi-vortex structure with an alternate arrangement along a body axis at high angle of attack. In this investigation, the effects of wing locations along a body axis on wing rock induced by forebody vortices was studied experimentally at a subcritical Reynolds number based on a body diameter. An artificial perturbation was added onto the nose tip to fix the orientations of forebody vortices. Particle image velocimetry was used to identify flow patterns of forebody vortices in static situations, and time histories of wing rock were obtained using a free-to-roll rig. The results show that the wing locations can affect significantly the motion patterns of wing rock owing to the variation of multi-vortex patterns of forebody vortices. As the wing locations make the forebody vortices a two-vortex pattern, the wing body exhibits regularly divergence and fixed-point motion with azimuthal variations of the tip perturbation. If a three-vortex pattern exists over the wing, however, the wing-rock patterns depend on the impact of the highest vortex and newborn vortex. As the three vortices together influence the wing flow, wing-rock patterns exhibit regularly fixed-points and limit-cycled oscillations. With the wing moving backwards, the newborn vortex becomes stronger, and wing-rock patterns become fixed-points, chaotic oscillations, and limit-cycled oscillations. With further backward movement of wings, the vortices are far away from the upper surface of wings, and the motions exhibit divergence, limit-cycled oscillations and fixed-points. For the rearmost location of the wing, the wing body exhibits stochastic oscillations and fixed-points.

  16. Polymorphic Ventricular Tachycardia/Ventricular Fibrillation and Sudden Cardiac Death in the Normal Heart.

    Science.gov (United States)

    Shah, Ashok J; Hocini, Meleze; Denis, Arnaud; Derval, Nicolas; Sacher, Frederic; Jais, Pierre; Haissaguerre, Michel

    2016-09-01

    Primary electrical diseases manifest with polymorphic ventricular tachycardia (PMVT) and ventricular fibrillation (VF) and along with idiopathic VF contribute to about 10% of sudden cardiac deaths (SCDs) overall. These disorders include long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, and early repolarization syndrome. This article reviews the clinical electrophysiological management of PMVT/VF in a structurally normal heart affected with these disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Disorders of Left Ventricular Trabeculation/Compaction or Right Ventricular Wall Formation

    Science.gov (United States)

    Shieh, Joseph T.C.; Jefferies, John L.; Chin, Alvin J.

    2013-01-01

    Cardiomyopathies are remarkably variable in form. Although hearts may be dilated or hypertrophic, the spectrum of cardiomyopathies includes left ventricular noncompaction/hypertrabeculation and right ventricular wall disorders. These conditions have been increasingly recognized in patients given advances in clinical diagnostics. Here we present information on cardiac pathophysiology, from ventricular wall formation and trabeculae in model organisms to pediatric and adult disease. Many genes to affect the ventricular phenotype, and this has implications for deciphering developmental and disease pathways and for applying testing for clinical care. PMID:23843328

  18. [Ventricular tachyarrhythmias in patients with cardiomyopathy

    DEFF Research Database (Denmark)

    Henningsen, K.; Christensen, A.H.; Svendsen, Jesper Hastrup

    2008-01-01

    INTRODUCTION: The purpose of this study was to determine the number and distribution of cardiomyopathies as the aetiology of ventricular tachyarrhythmias among patients discharged from the Department of Cardiology, Rigshospitalet. MATERIALS AND METHODS: The study was a retrospective review...... of patients discharged with the diagnostic codes ventricular tachycardia, ventricular fibrillation or premature ventricular contractions with cardiomyopathy as the presumed aetiology. Patients discharged during a period of 6 years and 5 months were included in the study. The patients were characterized...... by disease, gender, age, previous cardiac arrest and treatment with implantable cardioverter-defibrillator (ICD). RESULTS: 993 patients were screened and 128 patients with cardiomyopathy were identified, corresponding to 13% of the screened patients. 58 (45%) of the patients had dilated cardiomyopathy (DCM...

  19. Arrhythmogenic right ventricular dysplasia: A case report

    Directory of Open Access Journals (Sweden)

    Tessa Negrín Valdés

    2015-10-01

    Full Text Available Arrhythmogenic right ventricular dysplasia is a heart muscle disease that predominantly affects the right ventricle, bringing about the replacement of normal myocardium with fatty or fibrofatty tissue and causing sudden death in young individuals. Ventricular tachycardia is an important clinical manifestation, although there are reports of right or global heart failure. The diagnosis is confirmed by echocardiography and magnetic resonance imaging. The case of a 65-year-old former smoker, with hypertension and ischemic heart disease, a history of effort syncope symptoms and proven non-sustained ventricular tachycardia, with morphology of left bundle branch block, is reported. Relevant diagnostic studies were performed, and echocardiographic elements which were compatible with arrhythmogenic right ventricular dysplasia were found. Therefore, an implantable cardioverter defibrillator was implanted, after which the patient has had a favorable outcome.

  20. Catecholaminergic Polymorphic Ventricular Tachycardia in Pregnancy.

    Science.gov (United States)

    Romagano, Matthew P; Quiñones, Joanne N; Ahnert, Amy; Martinez, Rafael; Smulian, John C

    2016-04-01

    Catecholaminergic polymorphic ventricular tachycardia is a genetic disorder in which ventricular tachycardia occurs in the absence of structural heart disease or a prolonged QT interval. If untreated, there is a high incidence of sudden cardiac death. Management of this cardiac condition during pregnancy merits a multidisciplinary approach. A nulliparous woman with catecholaminergic polymorphic ventricular tachycardia presented at 15 weeks of gestation. Her care involved a multidisciplinary team including cardiology, maternal-fetal medicine, obstetric nursing, cardiac nursing, and anesthesia. A simulation scenario was designed to prepare for cardiac events during labor. A term intrapartum cesarean delivery was performed for fetal indications. A multidisciplinary approach to the antepartum, intrapartum, and postpartum care of women with catecholaminergic polymorphic ventricular tachycardia is critical to a team-based successful pregnancy outcome.