Lattice dynamics of b.c.c. alkaline-earth metals: Barium

Summary The attractive short-range component of the interatomic potential screens the conventional Born-Mayer potential in the framework of the resonance pseudopotential model. The elastic constants are evaluated at the long-wavelength limit of the phonon spectrum and the obtained results are compared with previous experimental values. The numerical calculations show that the attractive component of the potential explains the soft modes in this body-centred cubic (b.c.c.) alkaline-earth metal barium.     

A.c. Conductivity of reactive-evaporation-depositeda-Si:H films

Summary The electrical-conductivity frequency dependence of reactive-evaporation-depositeda-Si:H films has been measured in the temperature range (100÷450)K. The influence of the substrate temperature, of the hydrogen ions energy and of post-deposition thermal treatments has also been investigated. The results show that, depending on the material quality, three different conduction mechanisms associated with gap states, band or band tail states and to hopping processes near the Fermi level are observed.     

Informational processing of complex sound. III: interference.

In this study, theoretical results from information theory and detection theory are applied to provide a formal analysis of the interaction of target and context uncertainty on the discrimination of brief multitone sequences. The experiments employ a sample-discrimination task in which the performance of an ideal observer is held constant while the relative variability of the target sigmaT and context sigmaC is varied. Listener performance in these experiments was less than ideal but increased monotonically with sigmaT/sigmaC whether the task was to discriminate the frequency or the intensity of the target. Performance was also constant for a constant sigmaT/sigmaC regardless of the target's position in the sequence. The results are consistent with a class of models in which the decision variable is a weighted sum of the tone values comprising the sequence. Weighting functions computed from the trial-by-trial date suggest that limits in performance result from trial-by-trial variability in the weights. The decision variable also serves as the basis for an analysis in which performance is linearly related to the information rate of the context independent of target position or task. In this analysis, target and context uncertainty contribute additively to the overall uncertainty associated with the decision variable.