Alternative Methods for Computing the Sensitivity of Complex Surveillance Systems

Stochastic scenario trees are a new and popular method by which surveillance systems can be analyzed to demonstrate freedom from pests and disease. For multiple component systems—such as a combination of a serological survey and systematically collected observations—it can be difficult to represent the complete system in a tree because many branches are required to represent complex conditional relationships. Here we show that many of the branches of some scenario trees have identical outcomes and are therefore redundant. We demonstrate how to prune branches and derive compact representations of scenario trees using matrix algebra and Bayesian belief networks. The Bayesian network representation is particularly useful for calculation and exposition. It therefore provides a firm basis for arguing disease freedom in international forums.     

The Aesthetics of Aircraft Safety Cards: Spatial Negotiations and Affective Mobilities in Diagrammatic Instructions

Instructional diagrams encountered during transit, such as the aircraft safety card, employ a range of visual elements that direct us how to move and what actions we need to undertake. However, instructions are not always easy to decipher and comprehension rates suggest that there is potential for misinterpretation. The complexity of instructions and mismatching of visual techniques give rise to an aesthetics of transit that coordinates spatial experiences and movements. Using examples from aircraft safety cards and artworks based on this format, this paper analyses how ‘transit aesthetics’ can give rise to affective experiences of spatial and mobile relationships.     

Passion,Intimacy, and Commitment in Casual Sexual Relationships in a Canadian Sample of Emerging Adults

Research on casual sexual relationships (CSRs) among emerging adults is prevalent, yet our empirical and theoretical knowledge of relationship processes involved in these relationships is limited. The present study’s objective was to compare four CSR partner types (acquaintance, friend, non-dating partner, ex-romantic partner) on passion, intimacy, and commitment, the components of Sternberg’s triangular theory of love. A total of 441 Canadians aged 18–25 years who were not in a romantic relationship, and who reported having had more than one sexual contact with their last CSR partner, completed an online survey. Across all partner types, passion was highest, followed by intimacy and commitment. Levels of passion, intimacy, and commitment generally increased with partner familiarity. However, CSR partner type differences on the three components were partially explained by CSR components (i.e., frequency of sexual activity, frequency of social activity, whether partners saw each other with the main goal of having sex, sexual exclusivity agreement, and hopes about the relationship). Results are consistent with CSRs’ emphasis on sexuality, and, to a lesser extent, emotions. However, they challenge the mainstream and scientific conflation of CSRs with an absence of emotional bond, commitment, or love.     

Causes of Disaster: Sloppy Management

The loss of control associated with accidents and disasters can have severe negative consequences for the organizations involved. Some disasters are caused by inadequacies of management, or by unprofessional behaviour but others arise when disaster preconditions are generated as a result of the normal functioning of larger managerial and technical systems. During the incubation period preceding a major incident, therefore, two levels of correction need to be considered to avoid disasters. ‘Sloppy management’ of various kinds can be tackled by establishing, strengthening and asserting appropriate forms of management control. The system properties which constitute disaster preconditions are less immediately accessible to management control. At both levels managers in pursuit of high reliability should expect to have to make a range of trade-offs.     

A Characterization of a Matric-Variate Exponential Distribution

Suppose S is a positive definite m x m random matrix and S> Ω denotes the event that S—Ω is positive definite, Ω being a constant positive definite matrix. Under very mild regularity conditions, we show that the constraint Pr(S>Ω₁+Ω₂ | S>Ω₂) = Pr(S>Ω₁) implies that S has a Wishart distribution on m+ 1 degrees of freedom.