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

Development and application of a new measure of employee engagement: the ISA engagement scale

We present a new measure for assessing employee engagement. We build on Kahn’s (1990) theory and develop a model of engagement that has three requirements: a work-role focus, activation and positive affect. This model was operationalized in a new measure: the Intellectual, Social, Affective Engagement Scale (ISA Engagement Scale) comprising three facets: intellectual, social and affective engagement. Data from two studies showed that the scale and its sub-scales have internal reliability. There were associations with task performance, OCB and turnover intentions. Implications are provided for academic enquiry into the engagement process, and for HRD practices that enhance the experience of wor