A Spatio-Temporal Model for Functional Magnetic Resonance Imaging Data – with a View to Resting State Networks

Abstract.  Functional magnetic resonance imaging (fMRI) is a technique for studying the active human brain. During the fMRI experiment, a sequence of MR images is obtained, where the brain is represented as a set of voxels. The data obtained are a realization of a complex spatio-temporal process with many sources of variation, both biological and technical. We present a spatio-temporal point process model approach for fMRI data where the temporal and spatial activation are modelled simultaneously. It is possible to analyse other characteristics of the data than just the locations of active brain regions, such as the interaction between the active regions. We discuss both classical statistical inference and Bayesian inference in the model. We analyse simulated data without repeated stimuli both for location of the activated regions and for interactions between the activated regions. An example of analysis of fMRI data, using this approach, is presented.     

Evaluating correlated outcomes and sources of new information

This paper considers the difficulties associated with evaluating the expected value of additional information when the outcomes of various decision alternatives may be correlated. Such correlation is explained in terms of dependence of outcomes on common exogenous factors and it is argued that decisions regarding what, if any, additional information to collect should take such dependencies into account. A model-based ‘fixed-parameter’ approach to evaluating EVPI in such a context is developed and compared to the traditional ‘fixed-correlation’ approach. The results suggest that different assumptions about the issue of correlation can produce different, sometimes contradictory, conclusions about the expected value of additional information and bence, should be explicitly stated as part of any pre-posterior analysis. A hybrid model encompassing both approaches and rooted in the theory of psychology of inference is then proposed and illustrated.     

How NASA moved from R & D to operations

This paper investigates the initial planning process for the transition of an organization from a R & D environment to an Operations environment. Using a developed transition life cycle model, the paper demonstrates a four step analysis of the management of the transition. Further, the paper suggests the utilization of existing methods for achieving a smooth transformation under various levels of technical, political, cultural, managerial, and economic uncertainties. Finally, the paper lists possible courses of action and considerations for the transition once the initial planning stage is completed. The concepts herein were used to begin planning the change, from R & D to Operations, of the Space Shuttle Program at NASA.     

Testing of the ‘reduction of compound alternatives’ principle

This paper reports an empirical investigation of the effects of three pictorial forms of problem representation on conformance with the Reduction of Compound Alternatives Principle of expected utility theory. The most common form of representation, written problem statements, was compared with three pictorial representations: tubes containing one hundred labeled balls, decision matrices with each column proportional in size to the probability of the corresponding event, and bar graphs. The tubes representation led to fewer violations of the Principle. In addition, when subjects were trained to construct proportional matrices from written problem statements, they exhibited fewer violations than those who received the same problems already formatted in proportional matrices. The results reported here should contribute to the development of a theory of the way people frame decision problems.     

The traumatized children of violent marriages

Over three million children, it is estimated, witness parental violence annually. The clinical effects upon many children are characteristic of trauma, with dissociation and defensive protections against recall and resolution that can be pathological. This article presents the case for this assessment and describes the successful treatment of an eight-year-old-boy.     

EBV. Managing the physiological and psychosocial implications of the Epstein-Barr virus

EBV has both physiological and psychological implications. Few medical/nursing interventions are available to alleviate the physical stressors and fatigue. The primary nursing intervention, therefore, becomes one of providing emotional support and psychosocial interventions. Providing measures to ensure adequate sleep will assist the patient in more positive feelings about self. Although causation and diagnosis of this syndrome may be debated in the medical literature, the nursing role is to provide support and guidance for these patients. Longitudinal studies could be done to facilitate the understanding of the long-term effects of EBV and the outcome measures of mental health interventions.     

The Role of Work in Adolescent Development

This commentary discusses the articles in the special section, “Adolescent Career Development in Social Context.” Initially, common and integrative themes are identified and explicated based on the diverse perspectives of the work role in adolescence that were evident in these five articles. In addition, the theoretical frameworks provided by life-span, career development relational perspectives are discussed as possible means of integrating some of the findings presented by the authors of these articles. This article concludes with an observation on how the findings reported in the special section can inform career development scholarship and practice in the next millennium.     

Conservatism of the Accident Sequence Evaluation Program HRA Procedure

This paper presents a limited assessment of the conservatism of the Accident Sequence Evaluation Program (ASEP) human reliability analysis (HRA) procedure described in NUREG/CR-4772. The data for this study are derived from simulator examination reports from the NRC requalification examination cycle for nuclear power plant operators. The ASEP procedure was used to estimate human error probability (HEP) values for critical tasks, and the HEP results were compared with the failure rates observed in the examinations. The ASEP procedure was applied by PNNL operator license examiners who supplemented the limited information in the examination reports with expert judgment based upon their extensive simulator examination experience. Comparison of the average of the ASEP HEP values with the fraction of the population actually failed and demonstrated that the ASEP HEP values are larger (conservative) by a statistically significant average factor of two. Partitioning of tasks into subgroups based on the ASEP HEP values and comparison of the subgroup average ASEP HEP values with observed subgroup failure rates showed little or no conservatism for small ASEP HEP values, but considerable conservatism for larger ASEP HEP values.