In cache based multiprocessors a protocol must maintain coherence among replicated copies of shared writable data. In delayed consistency protocols the effect of out-going and in-coming invalidations or updates are delayed. Delayed coherence can reduce processor blocking time as well as the effects of false sharing. In this paper, we introduce several implementations of delayed consistency for cache-based systems in the framework of a weaklyordered consistency model. A performance comparison of the delayed protocols with the corresponding On-the-Fly (non-del~ed) consistency protocol is made, through execution-driven simulations of four parallel algorithms. The results show that, for parallel programs in which false sharing is a problem, signljlcant reductions in the data miss rate of parallel programs can be obtained with just a small increase in the cost and complexity of the cache system.

Sensory prediction errors are thought to update memories in motor adaptation, but the role of performance errors is largely unknown. To dissociate these errors, we manipulated visual feedback during fast shooting movements under visuomotor rotation. Participants were instructed to strategically correct for performance errors by shooting to a neighboring target in one of four conditions: following the movement onset, the main target, the neighboring target, both targets, or none of the targets disappeared. Participants in all conditions experienced a drift away from the main target following the strategy. In conditions where the main target was shown, participants often tried to minimize performance errors caused by the drift by generating corrective movements. However, despite differences in performance during adaptation between conditions, memory decay in a delayed washout block was indistinguishable between conditions. Our results thus suggest that, in visuomotor adaptation, sensory predictions errors, but not performance errors, update the slow, temporally stable, component of motor memory.

For children with severe cerebral palsy (CP), social and emotional interactions can be significantly limited due to impaired speech motor function. However, if it is possible to extract continuous voluntary control signals from the electromyograph (EMG) of limb muscles, then EMG may be used to drive the synthesis of intelligible speech with controllable speed, intonation and articulation. We report an important first step: the feasibility of controlling a vowel synthesizer using non-speech muscles. A classic formant-based speech synthesizer is adapted to allow the lowest two formants to be controlled by surface EMG from skeletal muscles. EMG signals are filtered using a non-linear Bayesian filtering algorithm that provides the high bandwidth and accuracy required for speech tasks. The frequencies of the first two formants determine points in a 2D plane, and vowels are targets on this plane. We focus on testing the overall feasibility of producing intelligible English vowels with myocontrol using two straightforward EMG-formant mappings. More mappings can be tested in the future to optimize the intelligibility. Vowel generation was tested on 10 healthy adults and 4 patients with dyskinetic CP. Five English vowels were generated by subjects in pseudo-random order, after only 10 min of device familiarization. The fraction of vowels correctly identified by 4 naive listeners exceeded 80% for the vowels generated by healthy adults and 57% for vowels generated by patients with CP. Our goal is a continuous “virtual voice” with personalized intonation and articulation that will restore not only the intellectual content but also the social and emotional content of speech for children and adults with severe movement disorders.

Sensory prediction errors are thought to update memories in motor adaptation, but the role of 1 performance errors is largely unknown. To dissociate these errors, we manipulated visual 2 feedback during fast shooting movements under visuomotor rotation. Participants were 3 instructed to strategically correct for performance errors by shooting to a neighboring target in 4 one of four conditions: following the movement onset, the main target, the neighboring target, 5 both targets, or none of the targets disappeared. Participants in all conditions experienced a drift 6 away from the main target following the strategy. In conditions where the main target was shown, 7 participants often tried to minimize performance errors caused by the drift by generating 8 corrective movements. However, despite differences in performance during adaptation between 9 conditions, memory decay in a delayed washout block was indistinguishable between conditions. 0Our results thus suggest that, in visuomotor adaptation, sensory predictions errors, but not 1 1 performance errors, update the slow, temporally stable, component of motor memory.