A Mobile Agent Framework to Support Parallel Computing: Application to Multi-product Planning and Scheduling Problems

This paper focuses on an extensible framework for the development of parallel/distributed population-based algorithms. This framework uses mobile agents launched into different hosts on available networked PCs and cooperating among them to solve large combinatorial problems efficiently. The execution environment used to realize our framework is based on the JADE technology. In addition, we define a new information exchange strategy based on a dynamic migration window method and a selective migration model. A parameters adaptation model is also proposed. This model is used to adjust different parameters/operators of the genetic algorithm executed by each mobile agent. The proposed framework has been experimented on an extended set of Earliness and Tardiness Production Scheduling and Planning Problem (ETPSP). Several experiments are carried out on different computer networks of different sizes. Results obtained show the advantages and efficiency of our approach

OUTER RETINAL TUBULATION IN ADVANCED AGE-RELATED MACULAR DEGENERATION: Optical Coherence Tomographic Findings Correspond to Histology

PURPOSE: To compare optical coherence tomography (OCT) and histology of outer retinal tubulation (ORT) secondary to advanced age-related macular degeneration in patients and in postmortem specimens, with particular attention to the basis of the hyperreflective border of ORT. METHOD: A private referral practice (imaging) and an academic research laboratory (histology) collaborated on two retrospective case series. High-resolution OCT raster scans of 43 eyes (34 patients) manifesting ORT secondary to advanced age-related macular degeneration were compared to high-resolution histologic sections through the fovea and superior perifovea of donor eyes (13 atrophic age-related macular degeneration and 40 neovascular age-related macular degeneration) preserve

Pitch Memory in Nonmusicians and Musicians: Revealing Functional Differences Using Transcranial Direct Current Stimulation

For music and language processing, memory for relative pitches is highly important. Functional imaging studies have shown activation of a complex neural system for pitch memory. One region that has been shown to be causally involved in the process for nonmusicians is the supramarginal gyrus (SMG). The present study aims at replicating this finding and at further examining the role of the SMG for pitch memory in musicians. Nonmusicians and musicians received cathodal transcranial direct current stimulation (tDCS) over the left SMG, right SMG, or sham stimulation, while completing a pitch recognition, pitch recall, and visual memory task. Cathodal tDCS over the left SMG led to a significant decrease in performance on both pitch memory tasks in nonmusicians. In musicians, cathodal stimulation over the left SMG had no effect, but stimulation over the right SMG impaired performance on the recognition task only. Furthermore, the results show a more pronounced deterioration effect for longer pitch sequences indicating that the SMG is involved in maintaining higher memory load. No stimulation effect was found in both groups on the visual control task. These findings provide evidence for a causal distinction of the left and right SMG function in musicians and nonmusician

An Agent Framework with an Efficient Information Exchange Model for Distributed Genetic Algorithms

Genetic Algorithms (GAs) are powerful search techniques that are used to solve difficult problems in many disciplines. Unfortunately, they can be very demanding in terms of computation load and memory. Parallel Genetic Algorithms (PGAs) are parallel implementations of GAs which can provide considerable gains in terms of performance and scalability. PGAs can easily be implemented on networks of heterogeneous computers or on parallel mainframes. In this paper, we introduce a multi-agent model conceived as a conceptual and practical framework for distributed genetic algorithms used both to reduce execution time and to get closer to optimal solutions. Instead of using expensive parallel computing facilities, our distributed model is implemented on easily available networked PCs. In order to show that the parallel co-evolution of different sub-populations may lead to an efficient search strategy, we design an efficient information exchange strategy based on different dynamic migration window methods and a selective migration model. To evaluate the proposed approach, different kinds of experiments have been conducted on an extended set of Capacitated Arc Routing Problem(CARP). Obtained results show the promise and efficiency of our agent-based approach

Probabilistic Inference for Fast Learning in Control

We provide a novel framework for very fast model-based reinforcement learning in continuous state and action spaces. The framework requires probabilistic models that explicitly characterize their levels of confidence. Within this framework, we use flexible, non-parametric models to describe the world based on previously collected experience. We demonstrate learning on the cart-pole problem in a setting where we provide very limited prior knowledge about the task. Learning progresses rapidly, and a good policy is found after only a hand-full of iterations

A causal involvement of the left supramarginal gyrus during the retention of musical pitches

Brain stimulation studies using transcranial direct current stimulation have shown that the processes involved in memorising pitch rely on activity within the left supramarginal gyrus (SMG). Building on this, the present study investigated which of the main phases of pitch memory processing may depend on the left SMG: retention or encoding. Repetitive transcranial magnetic stimulation (rTMS) was used to modulate the retention stage of a pitch memory task in Experiment 1 and the encoding phase in Experiment 2. Participants completed a pitch memory recognition task in which they had to decide whether two six tone long sequences were the same or different. Using a blocked design 5Hz rTMS was applied for 3 seconds on a trial-by-trial basis over either the left SMG (targeted site) or the Vertex (control site) during the retention phase (Experiment 1) or during encoding of the first sequence (Experiment 2). A baseline block (without rTMS) was also completed. For Experiment 1, a repeated measures ANOVA with stimulation condition (rTMS over left SMG vs rTMS over Vertex vs no stimulation) as the within-subject factor and reaction times as the dependent variable revealed a main effect of stimulation condition. Contrasts showed that only rTMS over the left SMG during retention led to significantly increased reaction times. In Experiment 2 no modulation effects were found when applying rTMS during encoding. Taken together, these findings highlight a phase-specific involvement of the left SMG for the retention period of pitch memory only, thereby indicating that the left SMG is involved for the perpetual storage of pitch information

Perceived emotions of harmonic cadences

Harmonic cadences are chord progressions that play an important structural role in Western classical music – they demarcate musical phrases and contribute to the tonality. This study examines participants’ ratings of the perceived arousal and valence of a variety of harmonic cadences. Manipulations included the type of cadence (authentic, plagal, half, and deceptive), its mode (major or minor), its average pitch height (the transposition of the cadence), the presence of a single tetrad (a dissonant four-tone chord), and the mode (major or minor) of the cadence’s final chord. With the exception of average pitch height, the manipulations had only small effects on arousal. However, the perceived valence of major cadences was substantially higher than for minor cadences, and average pitch had a medium-sized positive effect. Plagal cadences, the inclusion of a tetrad, and ending on a minor chord all had weak negative effects for valence. The present findings are discussed in light of contemporary music theory and music psychology, as knowledge of how specific acoustic components and musical structures impact emotion perception in music is important for performance practice, and music-based therapies