Minimising the Execution of Unknown Bag-of-Task Jobs with Deadlines on the Cloud

Scheduling jobs with deadlines, each of which defines the latest time that a job must be completed, can be challenging on the cloud due to incurred costs and unpredictable performance. This problem is further complicated when there is not enough information to effectively schedule a job such that its deadline is satisfied, and the cost is minimised. In this paper, we present an approach to schedule jobs, whose performance are unknown before execution, with deadlines on the cloud. By performing a sampling phase to collect the necessary information about those jobs, our approach delivers the scheduling decision within 10% cost and 16% violation rate when compared to the ideal setting, which has complete knowledge about each of the jobs from the beginning. It is noted that our proposed algorithm outperforms existing approaches, which use a fixed amount of resources by reducing the violation cost by at least two times.

An Automated Design Framework for Assembly Task Simulation

This paper presents an automated design framework for the development of individual part forming tools for a composite stiffener. The framework uses parametrically developed design geometries for both the part and its layup tool. The framework has been developed with a functioning user interface where part / tool combinations are passed to a virtual environment for utility based assessment of their features and assemblability characteristics. The work demonstrates clear benefits in process design methods with conventional design timelines reduced from hours and days to minutes and seconds. The methods developed here were able to produce a digital mock up of a component with its associated layup tool in less than 3 minutes. The virtual environment presenting the design to the designer for interactive assembly planning was generated in 20 seconds. Challenges still exist in determining the level of reality required to provide an effective learning environment in the virtual world. Full representation of physical phenomena such as gravity, part clashes and the representation of standard build functions require further work to represent real physical phenomena more accurately.

Praying for Salvation: A Map of Relatedness

This article attempts to push Mauss’ work on the sociality of prayer (1909) to its fullest conclusion by arguing that prayer can be viewed anthropologically as providing a map for social and emotional relatedness. Based on fieldwork among deep-sea fisher families living in Gamrie, North-East Scotland (home to 700 people and six Protestant churches), the author takes as his primary ethnographic departure the ritual of the ‘mid-week prayer meeting’. Among the self-proclaimed ‘fundamentalists’ of Gamrie’s Brethren and Presbyterian churches, attending the prayer meeting means praying for salvation. Yet, contrary to the stereotype of Protestant soteriology as highly individualist, in the context of Gamrie, salvation is not principally focused upon the self, but is instead sought on behalf of the ‘unconverted’ other. Locally, this ‘other’ is made sense of with reference to three different categories of relatedness: the family, the village and the nation. The author’s argument is that each category of relatedness carries with it a different affective quality: anguish for one’s family, resentment toward one’s village, and resignation towards one’s nation. As such, prayers for salvation establish and maintain not only vertical – human-divine – relatedness, but also horizontal relatedness between persons, while also giving them their emotional tenor. In ‘fundamentalist’ Gamrie, these human relationships, and crucially their affective asymmetries, may be mapped, therefore, by treating prayers as social phenomena that seek to engage with a world dichotomised into vice and virtue, rebellion and submission, and, ultimately, damnation and salvation.

Neural adaptations associated with interlimb transfer in a ballistic wrist flexion task.

Cross education is the process whereby training of one limb gives rise to increases in the subsequent performance of its opposite counterpart. The execution of many unilateral tasks is associated with increased excitability of corticospinal projections from primary motor cortex (M1) to the opposite limb. It has been proposed that these effects are causally related. Our aim was to establish whether changes in corticospinal excitability arising from prior training of the opposite limb determine levels of interlimb transfer.

We used three vision conditions shown previously to modulate the excitability of corticospinal projections to the inactive (right) limb during wrist flexion movements performed by the training (left) limb. These were: mirrored visual feedback of the training limb; no visual feedback of either limb; and visual feedback of the inactive limb. Training comprised 300 discrete, ballistic wrist flexion movements executed as rapidly as possible. Performance of the right limb on the same task was assessed prior to, at the mid point of, and following left limb training.

There was no evidence that variations in the excitability of corticospinal projections (assessed by transcranial magnetic stimulation (TMS)) to the inactive limb were associated with, or predictive of, the extent of interlimb transfer that was expressed. There were however associations between alterations in muscle activation dynamics observed for the untrained limb, and the degree of positive transfer that arose from training of the opposite limb.

The results suggest that the acute adaptations that mediate the bilateral performance gains realised through unilateral practice of this ballistic wrist flexion task are mediated by neural elements other than those within M1 that are recruited at rest by single-pulse TMS.

Transposing Musical Skill: Sonification of movement as concurrent augmented feedback enhances learning in a bimanual task

Concurrent feedback provided during acquisition can enhance performance of novel tasks. The ‘guidance hypothesis’ predicts that feedback provision leads to dependence and poor performance in its absence. However, appropriately-structured feedback information provided through sound (‘sonification’) may not be subject to this effect. We test this directly using a rhythmic bimanual shape-tracing task in which participants learned to move at a 4:3 timing ratio. Sonification of movement and demonstration was compared to two other learning conditions: (1) sonification of task demonstration alone and (2) completely silent practice (control). Sonification of movement emerged as the most effective form of practice, reaching significantly lower error scores than control. Sonification of solely the demonstration, which was expected to benefit participants by perceptually unifying task requirements, did not lead to better performance than control. Good performance was maintained by participants in the sonification condition in an immediate retention test without feedback, indicating that the use of this feedback can overcome the guidance effect. On a 24-hour retention test, performance had declined and was equal between groups. We argue that this and similar findings in the feedback literature are best explained by an ecological approach to motor skill learning which places available perceptual information at the highest level of importance.