نتایج جستجو برای: pressure wave

تعداد نتایج: 612837  

2017
Richard Petersson J Gustav Smith David A Larsson Öyvind Reitan Jonas Carlson Pyotr Platonov Fredrik Holmqvist

BACKGROUND It has previously been shown that the morphology of the P-wave neither depends on atrial size in healthy subjects with physiologically enlarged atria nor on the physiological anatomical variation in transverse orientation of the left atrium. The present study aimed to investigate if different pressures in the left and right atrium are associated with different P-wave morphologies. ...

Journal: :Annales de recherches veterinaires. Annals of veterinary research 1984
M N Rao O Ramakrishna D S Vijaykumar

Sine, triangular and square wave alternating currents were used to anaesthetize young buffalo calves. Central venous pressure, systolic and diastolic blood pressure and circulatory rate were monitored before, during and after application of currents. The square and triangular wave current produced a significant (P less than 0.01) increase in central venous pressure, mean systolic and diastolic ...

2017
Ye Li Haotian Gu Henry Fok Jordi Alastruey Philip Chowienczyk

We tested the hypothesis that increased pulse wave reflection and altered backward waveform morphology contribute to increased pulse pressure in subjects with higher pulse pressure compared with lower pulse pressure and to actions of vasoactive drugs to increase pulse pressure. We examined the relationship of backward to forward wave morphology in 158 subjects who were evaluated for hypertensio...

Journal: :Hypertension 2015
N Westerhof P Segers B E Westerhof

Wave separation analysis and wave intensity analysis (WIA) use (aortic) pressure and flow to separate them in their forward and backward (reflected) waves. While wave separation analysis uses measured pressure and flow, WIA uses their derivatives. Because differentiation emphasizes rapid changes, WIA suppresses slow (diastolic) fluctuations of the waves and renders diastole a seemingly wave-fre...

2010
Justin E. Davies John Baksi Darrel P. Francis Nearchos Hadjiloizou Zachary I. Whinnett Charlotte H. Manisty Jazmin Aguado-Sierra Rodney A. Foale Iqbal S. Malik John V. Tyberg Kim H. Parker Jamil Mayet Alun D. Hughes

The augmentation index predicts cardiovascular mortality and is usually explained as a distally reflected wave adding to the forward wave generated by systole. We propose that the capacitative properties of the aorta (the arterial reservoir) also contribute significantly to the augmentation index and have calculated the contribution of the arterial reservoir, independently of wave reflection, a...

2013
A. R. McMillan W. M. Isbell A. H. Jones Allan R. McMillan William M. Isbell Arfon H. Jones

The attenuation of high pressure shock waves has been investigated. High purity copper, 6061-T6 aluminum, 6A1-4V and a phase titanium, an uranium alloy and two alloys of beryllium were examined experimentally at pressures as high as 3 megabars. Low pressure experiments were instrumented with a velocity laser interferometer. Intermediate pressures (to several hundred kilobars) were instrumented ...

Journal: :European journal of clinical investigation 2005
J E Sharman C M McEniery R I Campbell J S Coombes I B Wilkinson J R Cockcroft

BACKGROUND Brachial blood pressure predicts cardiovascular outcome at rest and during exercise. However, because of pulse pressure amplification, there is a marked difference between brachial pressure and central (aortic) pressure. Although central pressure is likely to have greater clinical importance, very little data exist regarding the central haemodynamic response to exercise. The aim of t...

Journal: :Journal of the Japan Society for Precision Engineering 1989

   In this paper, numerical results obtained and explained from an exact formula in relation to sound pressure load due to the presence of liquid inside the finite-length non-rigid carbon nanotubes (CNTs), which is coupled with the dynamic equations of motion for the CNT. To demonstrate the accuracy of this work, the obtained formula has been compared to what has been used by other research...

Journal: :Hypertension 2015
Hendrik L Booysen Angela J Woodiwiss Moekanyi J Sibiya Bryan Hodson Andrew Raymond Elena Libhaber Pinhas Sareli Gavin R Norton

Although indexes of wave reflection enhance risk prediction, the extent to which measures of aortic systolic pressure augmentation (augmented pressures [Pa] or augmentation index) underestimate the effects of reflected waves on cardiovascular risk is uncertain. In participants from a community sample (age >16), we compared the relative contribution of reflected (backward wave pressures and the ...

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