Ada-Based support for programming-in-the-Large

Specialized language features and an integrated set of tools can help developers of a large software system describe, analyze, organize, and manage its many modules.     

Comparison of personalized cueing and provided cueing on the facilitation of verbal labeling by aphasic subjects

This study investigated the effects of two associative learning tasks on aphasic subjects' labeling of novel symbols. It was designed to determine if aphasic subjects need to develop their own associations for word-symbols pairs (personalized cueing) to obtain the long-term labeling benefits observed in prior research or if comparable results are obtained when "ready-made" associations are used during training (provided cueing). The results showed that the two cueing techniques were equal in their ability to elicit correct responses from the subjects. The results also demonstrated the long-term effectiveness of both cueing procedures on the subjects' labeling accuracy up to 30 days after training was discontinued.     

Measurements of the relaxation of quasiparticle branch imbalance in superconductors

An imbalanceQ in the quasiparticle populations of thek>k _F andk _F branches of a superconductor may be generated by the injection of a current through a tunnel barrier. This imbalance relaxes with a characteristic timeτ _Q . The steady-state value ofQ gives rise to a quasiparticle potentialV that differs from the pair chemical potential, and which may be measured by a second tunnel junction. Tinkham's theory of these effects is briefly reviewed. Detailed experimental results are presented for tin. Most of the data are for injection voltages much greater than the energy gapΔ(T). Close to the transition temperatureT _c ,Q relaxes by inelastic phonon scattering, andτ _Q ^ph =(1.0±0.2)×10^?10 Δ(0)/Δ(T) sec. This time is about one-half that estimated by Tinkham. At temperatures somewhat belowT _c, elastic scattering also contributes to theQ relaxation, provided the superconducting energy gap is anisotropic. With a size-effect-limited mean free path of about 2800 Å, we findτ _Q ^el ≈1.4×10^?10 sec forT/T _c <0.6, a value that is also in good agreement with Tinkham's theory. In a sample with a mean free path of 420 Å, and a greatly reduced anisotropy,τ _Q ^el was increased to about 10^?9 sec. Data were also taken for injection voltages close toΔ(T)/e. The degree of imbalance per unit injection current was greatly reduced, as predicted by the theory. Preliminary measurements were made on lead. At 4.2K (T/T _c =0.58) the characteristic time was about 3×10^?12 sec. The quasiparticle potential apparently increased steadily as the temperature was lowered, probably indicating that the characteristic time also increased. This result is not well understood. However, it is possible that recombination processes play a role in theQ relaxation in lead.