Cusp geometry analysis in free-form surface machining

The measurement of cusp height is the conventional method for determining the amount of excess material on free-form machined surfaces, and is frequently used to justify surface quality at the design and manufacturing stages. Although, such surface assessment strategies are generally accepted by manufacturers and customers, they may not provide enough information to qualify the machined surfaces. The aim of this work is to develop a new surface assessment method, for the machined surfaces by determining the area and the volume of the cusps. The method is built on analytic mathematical models of the surfaces and enhanced by the explicit forms of the cusp area and volume equations. The accuracy and reliability of these analytical formulations have been tested with data from machining trials and comparisons with a commerical software package. The indications are that this new approach offers a more comprehensive surface assessment strategy than the conventional measuring method.     

Full motion and flow field recovery from echo Doppler data

We present a new computational method for reconstructing a vector velocity field from scattered, pulsed-wave ultrasound Doppler data. The main difficulty is that the Doppler measurements are incomplete, for they do only capture the velocity component along the beam direction. We thus propose to combine measurements from different beam directions. However, this is not yet sufficient to make the problem well posed because 1) the angle between the directions is typically small and 2) the data is noisy and nonuniformly sampled. We propose to solve this reconstruction problem in the continuous domain using regularization. The reconstruction is formulated as the minimizer of a cost that is a weighted sum of two terms: 1) the sum of squared difference between the Doppler data and the projected velocities 2) a quadratic regularization functional that imposes some smoothness on the velocity field. We express our solution for this minimization problem in a B-spline basis, obtaining a sparse system of equations that can be solved efficiently. Using synthetic phantom data, we demonstrate the significance of tuning the regularization according to the a priori knowledge about the physical property of the motion. Next, we validate our method using real phantom data for which the ground truth is known. We then present reconstruction results obtained from clinical data that originate from 1) blood flow in carotid bifurcation and 2) cardiac wall motion.     

High-performance immunoassays based on through-stencil patterned antibodies and capillary systems

We present a simple method to pattern capture antibodies (cAbs) on poly(dimethylsiloxane) (PDMS), with high accuracy and in a manner compatible with mass fabrication for use with capillary systems (CSs), using stencils microfabricated in Si. Capture antibodies are patterned as 60-270 microm wide and 2 mm long lines on PDMS and used with CSs that have been optimized for convenient handling, pipetting of solutions, pumping of liquids, such as human blood serum, and visualization of signals for fluorescence immunoassays. With the use of this method, C-reactive protein (CRP) is detected with a sensitivity of 0.9 ng mL(-1) (7.8 pM) in 1 microL of CRP-spiked human serum, within 11 min and using only four pipetting steps and a total volume of sample and reagents of 1.35 microL. This exemplifies the high performances that can be achieved using this approach and an otherwise conventional surface sandwich fluorescence immunoassay. This method is simple and flexible and should therefore be applicable to a large number of demanding immunoassays.     

Ehanced biliary thyroxine excretion in rats treated with pregnenolone-16alpha-carbonitrile

Normal rats were treated with pregnenolone- 16alpha - carbonitrile (PCN) 10 mg/100 g by stomach tube twice daily for 3 days. In these animals the biliary excretion of intravenously injected 125I-thyroxine (T4) was enhanced and the bile: plasma 125I ratio (B/P ratio) and the biliary clearance rate of plasma 125I-T4 was increased. Normal rats were treated with PCN for 3 days and homozygous Gunn rats for 13 days. In both groups PCN enhanced the bile flow and elevated the B/P ratios and the biliary clearance rate of plasma T4 following ip injection of 125I-T4 17 h previously. PCN-treatment had no effect on the fractions of biliary 125I present as T4-glucuronide, T4 and I- in either the normal or Gunn rats. Treatment with PCN for 10 days produced goitres in normal and Gunn rats and in normal rats elevated the serum TSH (bioassay) levels and the 17 h thyroid 131I uptake as well as the serum PB125I concentrations, without affecting stable PBI concentrations. These data indicated increased pituitary TSH release in response to increased peripheral metabolism of thyroid hormone; enhanced hormonal release from the thyroid kept pace with the accelerated peripheral loss.