Axial velocities were measured in an enlarged, two-dimensional, rigid model of the carotid artery bifurcation by means of a laser-Doppler anemometer, under both steady and unsteady flow conditions. Also a numerical model was developed, based on the finite element approximation of the Navier-Stokes and continuity equations. From this study it appeared that the numerically predicted velocities ag...

This study presents a novel method for automatic measurement of the anteroposterior diameter of the thyroid gland, in ultrasound images. Anteroposterior diameter is widely considered a basic parameter for goiter assessment. Goiter refers to abnormal enlargement of the thyroid gland and it is associated with iodine deficiency and various pathologic conditions including Hashimoto’s thyroiditis, a...

Solid-state nanopores are widely acknowledged as tools with which to study local structure in biological molecules. Individual molecules are forced through a nanopore, causing a characteristic change in an ionic current that depends on the molecules' local diameter and charge distribution. Here, the translocation measurements of long (~5-30 kilobases) single-stranded poly(U) and poly(A) molecul...

We tested the hypothesis that under physiological conditions, arterioles match their diameter to the level of shear stress. Haemodynamic and anatomical data were obtained in segments of the first-order arteriole of the rat cremaster muscle. Along this segment of ~10 mm in length, local blood pressure decreased from 68 +/- 4 mmHg upstream to 54 +/- 3 mmHg downstream (n = 5). Pulse pressure decre...

The cellular mechanisms that control arterial diameter in vivo, particularly in hypertension, are uncertain. Here, we report a method that permits arterial intracellular Ca(2+) concentration ([Ca(2+)](i)), myosin light-chain kinase (MLCK) activation, and artery external diameter to be recorded simultaneously with arterial blood pressure (BP) in living mice under 1.5% isofluorane anesthesia. The...

Although venous capacitance has been studied in the neurally isolated tissue or in the in vitro vein segment, this is the first study of sympathetic regulation of the pressure-diameter relation in mesenteric veins in situ, where innervation is kept intact. In 25 alpha-chloralose-anesthetized rabbits, mesenteric vein diameter (679 +/- 27 microns, ranges of 380-1,050 microns at initial state) and...

We analyze simple morphological configurations that represent gap-junctional coupling between neuronal processes or between muscle fibers. Specifically, we use cable theory and simulations to examine the consequences of current flow from one cable to other gap-junctionally coupled passive cables. When the proximal end of the first cable is voltage clamped, the amplitude of the electrical signal...

From the known statistics of fiber-fiber contacts in random fiber networks, an analytic estimate is obtained for the variance of local porosity in random fiber suspensions and evolving filtrate networks. The variance of local porosity, and hence the distribution of projected areal density, seem to depend on fiber geometry only through the cube of mean diameter. Also, the coefficient of variatio...

From the known statistics of fibre-fibre contacts in random fibre networks, an analytic estimate is obtained for the variance of local porosity in random fibre suspensions and evolving filtrate networks. The variance of local porosity, and hence the distribution of projected areal density, seems to depend on fibre geometry only through the cube of mean diameter. Also, the coefficient of variati...