Trapped surfaces and symmetries

We prove that strictly stationary spacetimes cannot contain closed trapped nor marginally trapped surfaces. The result is purely geometric and holds in arbitrary dimension. Other results concerning the interplay between (generalized) symmetries and trapped submanifolds are also presented.Comment: 9 pages, no figures. Final corrected version to appear in Class. Quantum Gra

A Case-base Approach to Workforces’ Satisfaction Assessment

It is well known that human resources play a valuable role in a sustainable organizational development. Indeed, this work will focus on the development of a decision support system to assess workers’ satisfaction based on factors related to human resources management practices. The framework is built on top of a Logic Programming approach to Knowledge Representation and Reasoning, complemented with a Case Based approach to computing. The proposed solution is unique in itself, once it caters for the explicit treatment of incomplete, unknown, or even self-contradictory information, either in terms of a qualitative or quantitative setting. Furthermore, clustering methods based on similarity analysis among cases were used to distinguish and aggregate collections of historical data or knowledge in order to reduce the search space, therefore enhancing the cases retrieval and the overall computational process

Work engagement and voluntary absence: The moderating role of job resources

The present study examined the moderating role of job resources, namely, organisational trust, the quality of employees’ relationship with their manager, and the motivating potential of jobs, on the negative relationship between work engagement and voluntary absence. Employee survey results and absence records collected from the Human Resources Department of a construction and consultancy organisation in the United Kingdom (n=325) showed that work engagement was negatively related to voluntary absence, as measured by the Bradford Factor. Further, the results showed that organisational trust and the quality of employees’ relationships with their line managers ameliorated the negative effect of relatively low levels of engagement on voluntary absence. Theoretical and practical implications of the findings are discussed

Placing relationships in the foreground: the role of workplace friendships in engagement

We explore the role of workplace friendships as a lens for understanding the emotional element and relational context for personal engagement (Kahn, 1990). The review of engagement theory differentiates personal engagement, recognising the role emotions play in enabling individuals’ ‘preferred selves’. Workplace relationships and friendship provide a conceptual discussion of individuals in social and workplace roles in engagement, drawing on friendship, emotion, attachment theories, particularly Kahn’s work. A case study drawn from recent research illustrates our discussion before concluding with ideas for the development of a future research agenda in answer to recent calls for work on the social context of engagement

Dual task effect on postural control in patients with degenerative cerebellar disorders

BackgroundThe cerebellum plays an important role for balance control and the coordination of voluntary movements. Beyond that there is growing evidence that the cerebellum is also involved in cognitive functions. How ataxic motor symptoms are influenced by simultaneous performance of a cognitive task, however, has rarely been assessed and some of the findings are contradictory. We assessed stance in 20 patients with adult onset degenerative almost purely cerebellar disorders and 20 healthy controls during single and dual task conditions (verbal working memory task). To objectively measure postural sway and the impact of somatosensory, visual and vestibular inputs we used static and dynamic posturography with the Sensory Organization Test (SOT).ResultsIn both groups, cerebellar patients and controls, dual tasking reduced all sway parameters. Reduction of sway path was higher in cerebellar patients and increased with the difficulty of the postural task. The frequency of falls was higher in the patients group especially during the more challenging conditions and dual task performance in particular increased the risk of falls in cerebellar patients.ConclusionDual task conditions had a larger impact on sway parameters in patients with chronic cerebellar disorders than in healthy controls and lead to an increased risk of falls. As performing two tasks simultaneously is common and therefore important in daily life dual task exercises should be part of physical therapy programs for cerebellar patients