OBJECTIVE While chronic cerebrospinal venous insufficiency (CCSVI) can be characterized using cervical plethysmography, much remains unknown about the haemodynamics associated with this procedure. The aim of the study was therefore to gain a deeper understanding of the observed haemodynamics. METHOD Forty healthy controls and 44 CCSVI patients underwent cervical plethysmography, which involve...

The hydraulic resistance of vegetation can play a major role in the hydrodynamics of vegetated streams or rivers with extensive natural floodplains. Contrary to commonly used wall roughness methods, vegetation penetrates the flow field causing drag and, subsequently, additional energy losses. Klopstra et al. (1997) derived an analytical solution of the flow velocity profile over and through a f...

In an axial flow machine, fluids flow condition, that is flow pattern in a rotating flow passage changes its form and magnitude by the hydraulic resistance to the fluid flow in flow passage. Effect of centrifugal force becomes stronger with the increase of hydraulic resistance, and the flow rate becomes smaller. And, in the comparison of fluids flow condition among different axial flow machines...

We studied the effect of scion donor-tree age on the physiology and growth of 6- to 7-year-old grafted Scots pine (Pinus sylvestris L.) trees (4 and 5 years after grafting). Physiological measurements included photosynthethetic rate, stomatal conductance, transpiration, whole plant hydraulic conductance, needle nitrogen concentration and carbon isotope composition. Growth measurements included ...

Hydraulic conductance exerts a strong influence on many aspects of plant physiology, namely: transpiration, CO2 assimilation, growth, productivity or stress response. However we lack full understanding of the contribution of root or shoot water transport capacity to the total water balance, something which is difficult to study in trees. Here we tested the hypothesis that whole plant hydraulic ...

Hydraulic architecture parameters, water relation parameters and wood anatomy were studied in roots and shoots of the flood-tolerant tree Annona glabra L. on Barro Colorado Island, Panama. Hydraulic conductivity, leaf specific conductivity, and Huber value were similar to the corresponding values for tree species living in non-flooded habitats. The vulnerability of stems to loss of hydraulic co...

We examined the effects of graded reduction of afterload on the global left ventricular and regional myocardial functions as well as coronary hemodynamics in hearts with regional ischemia. We used isolated, paced canine hearts that were loaded with a hydraulic system that simulated the aortic input impedance of the dog's arterial tree. The loading conditions could be quantitatively and sequenti...

In environmental flood management, an essential task is to improve channel conveyance using environmentally preferable methods, which aim to preserve natural morphological and hydraulic characteristics of a river. This requires a reliable channel design method that accounts for complex hydraulics, i.e. two-stage channel or considerable bank vegetation. Hydraulic field measurements were carried ...

The results of an experimental investigation of kerbside bridge deck drainage units are presented. The conveyance capacity, resistance coefficients and sediment transporting efficiencies of different types of drainage unit used in shallow bridge drainage decks are examined over a range of bed gradients likely to be encountered in practice. The use of a V-shaped cross section is shown to be part...

We examined the effects of graded reduction of afterload on the global left ventricular and regional myocardial functions as well as coronary hemodynamics in hearts with regional ischemia. We used isolated, paced canine hearts that were loaded with a hydraulic system that simulated the aortic input impedance of the dog's arterial tree. The loading conditions could be quantitatively and sequenti...