OBJECTIVE The clinical manifestations of acromegalic cardiomyopathy include arrhythmias, valvular regurgitation, concentric left ventricular (LV) hypertrophy, and LV systolic and diastolic dysfunction. At present, it is unknown whether acromegaly also affects the aortic root. DESIGN Aortic root diameters were prospectively assessed in 37 acromegalic patients (18 patients with active disease a...

The stability of wavy supercritical cylindrical Couette flow has been studied extensively, but few measurements of the velocity field in flow have been made. Particle image velocimetry was used to measure the azimuthal and radial velocities in latitudinal planes perpendicular to the axis of rotation for wavy cylindrical Couette flow in the annulus between a rotating inner cylinder and a fixed o...

Natural convection heat transfer was investigated experimentally in a concentric-cylinders annulus. To enhance the rate of heat transfer, pin fins were installed on the surface of the inner cylinder. Two fin arrangements were employed, namely, staggered and in-line arrangements. The length of the fins varied from 2 to 8 cm and the Rayleigh number Ra changed in the range from 5 x 105  to 5 x 106...

PURPOSE Both non-arteritic anterior ischemic optic neuropathy (NAION) and primary open-angle glaucoma (POAG) damage retinal ganglion cell axons, which are perfused by the radial peripapillary capillaries. To evaluate the pattern of ischemia, we compared peripapillary capillary density (PCD) in NAION eyes to POAG eyes matched for visual field mean deviation and retinal nerve fiber layer thicknes...

A numerical study has been carried out to investigate the heat transfer by natural convection of nanofluid taking Cu as nanoparticles and the water as based fluid in a three dimensional annulus enclosure filled with porous media (silica sand) between two horizontal concentric cylinders with 12 annular fins of 2.4mm thickness attached to the inner cylinder under steady state conditions. The gove...

As long ago as 1962 Nitsche conjectured that a harmonic homeomorphism h: A(r, R) onto −→A(r∗, R∗) between planar annuli exists if and only if R∗ r∗ 1 2 ( R r + r R ) . We prove this conjecture when the domain annulus is not too wide; explicitly, when R e3/2r. We also treat the general annuli A(r, R), 0 < r < R < ∞, and obtain the sharp Nitsche bound under additional assumption that either h or ...

Recently, there has been a growing interest in using induced electro-osmosis to pump fluids in microfluidic devices. We show that induced electroosmosis can also be used to promote stirring and chaotic advection. To this end, we study theoretically a stirrer in which the flow patterns are alternated in time. We first analyze an idealized embodiment of the stirrer that admits a simple analytical...

Let P be a convex polyhedron in R3. The skeleton of P is the graph whose vertices and edges are the vertices and edges of P , respectively. We prove that, if these vertices are on the unit-sphere, the skeleton is a (0.999 · π)-spanner. If the vertices are very close to this sphere, then the skeleton is not necessarily a spanner. For the case when the boundary of P is between two concentric sphe...

We discuss the behavior of the minimal eigenvalue λ of the Dirichlet Laplacian in the domainD1\D2 := D (an annulus) whereD1 is a circular disc andD2 ⊂ D1 is a smaller circular disc. It is conjectured that the minimal eigenvalue λ has a maximum value when D2 is a concentric disc. If h is a displacement of the center of the disc D2 and λ(h) is the corresponding minimal eigenvalue, then dλ(h) dh <...

In this paper, we present experimental investigation of convective heat transfer characteristic in the inner tube fluid of miniature concentric double tube Hair-pin heat exchanger with constant heat flux. This work is carried out for distilled water and a mixture of distilled water and ethylene glycol (10%, 20% and 25% by volume) as heat transfer cold fluid flowing in inner tube to carry away h...