Electromechanical properties of high coupling single crystals under large electric drive and uniaxial compression

This work investigates the 33-mode electromechanical response of relaxor-ferroelectric lead magnesium niobate-lead titanate (PMN-PT) single crystals when driven with large fields approximately 0.4 MV/m under a combined direct current (DC) field and mechanical bias similar to those used in the design of sound projectors. It demonstrates that the remarkable small signal length extensional coupling (k33 > 0.90) and other electromechanical properties of morphotropic PMN-PT single crystals prevail under large drive. The observed k33 roll-off at 42 MPa compressive stress is analyzed in terms of the recent structural data and the high-order Devonshire theory of possible ferroelectric-ferroelectric transition trajectories.     

Query costs in HB(1) trees versus 2–3 trees

Query costs in random AVL trees are compared to those in random 2–3 trees. Both data structures are assumed to reside in main storage. Costs are calculated in terms of the number of node visits and key comparisons required to find a match or no match for a given key. The comparison is based upon theoretical concepts and implementation dependent considerations; e.g., data and instruction fetch. It is shown that if the cost of a key comparison is greater than or equal to the cost of a node access, then AVL trees are more advantageous.     

Molecular aggregation in poly(vinyl chloride). A novel analytical technique

A novel experimental technique based on gel permeation chromatography (GPC) has been developed for the measurement of molecular aggregation in poly(vinyl chloride) (PVC). PVC having a range of syndiotacticity was synthesized using polymerization temperatures of 30–70°C. Tacticity and molecular aggregation of these PVC samples were measured by NMR and GPC, respectively. The temperature dependence of molecular aggregation was found to be much greater than that of tacticity. This GPC technique is inherently more sensitive than NMR in the temperature range normally employed for commercial production of PVC. It should find extensive use in the control of PVC reactors and in PVC processing.     

On optimal parameter selection

Pontryagin's results on optimal parameter selection problems [1, p. 193] have been found to contain some errors, as reported in Boltyanskii [2, p. 263] and Hofer and Sagirow [4]. In this note, it is shown that Boltyanskii's results (on optimal parameters) are easily derived from Gamkrelidze's general maximum principle [3], which, in contrast to the former, also yields an explicit solution to the problem in certain special cases.     

Evaluation and treatment of urinary tract infections in children

Urinary tract infections (UTIs) are among the most common bacterial infections encountered by primary care physicians. Although UTIs do not occur with as great a frequency in children as in adults, they can be a source of significant morbidity in children. For reasons that are not yet completely understood, a minority of UTIs in children progress to renal scarring, hypertension and renal insufficiency. Clinical presentation of UTI in children may be nonspecific, and the appropriateness of certain diagnostic tests remains controversial. The diagnostic work-up should be tailored to uncover functional and structural abnormalities such as dysfunctional voiding, vesicoureteral reflux and obstructive uropathy. A more aggressive work-up, including renal cortical scintigraphy, ultrasound and voiding cystourethrography, is recommended for patients at greater risk for pyelonephritis and renal scarring, including infants less than one year of age and all children who have systemic signs of infection concomitant with a UTI. Antibiotic prophylaxis is used in patients with reflux or recurrent UTI who are at greater risk for subsequent infections and complications.     

Linking assembly code to PASCAL programs for microprocessors

High level languages used for programming microprocessors still need some assembly code to cover all the programming requirements and aspects. Using assembly code in a high level language program introduces certain difficulties and disadvantages. Practical suggestions to minimise the use of assembly code procedures in a high level language program is presented. (The high level language discussed is pascal/64000.)     

Vectors for Cu2+-inducible production of glutathione S-transferase-fusion proteins for single-step purification from yeast

We describe six new yeast episomal vectors which encode glutathione S-transferase (GST) affinity tags. These allow for the production of GST-fusion proteins in Saccharomyces cerevisiae under the control of the CUP1 promoter. Affinity chromatography with glutathione-Sepharose permits convenient purification of the fusion protein from a yeast lysate. The presence of a protease cleavage site facilitates subsequent removal of the GST tag. The expression and single-step purification of both GST and a functional GST-metallothionein fusion from yeast are shown as an example of the application of these vectors.