Online Structure, Parameter, and Utility Updating of Bayesian Decision Networks for Cooperative Decision-Theoretic Agents

Multi-agent systems, systems consisting of more than one acting and decision making entities, are of great interest to researchers because they have advantages for some specific tasks where it would be more effective to use multiple small and simple robots rather than a large and complex one. One of the major problems with multi-agent systems is developing a means to organize or control the overall behavior of the system. Typically, multi-agent control involves one of two structures. In some designs, there is a hierarchy with some robots being leaders and other followers. Other designs involve robot specialization towards one particular task or individual robots which loosely or strongly cooperate in some manner to yield the desired behavior. This thesis studies using bayesian decision networks (BDNs) as a method to control individual robots to achieve some group or cooperative behavior. BDNs are powerful tools enabling designers of intelligent agents to model the agent\u27s environment and the behavior of other agents without expert knowledge about a system. The probabilistic nature of these networks allows agents to learn about themselves and their environment by updating their bayesian network (BN) with new observations. While two methods of learning and responding to change in the environment with BNs, parameter learning and structure learning, have been studied by many researchers as a means to control a single robot or teams of robots, a third method, utility updating, has seen little study. This work is thus a novel study of BN control since it incorporates all three methods to develop a decision theoretic agent (DTA). The agent is applied to a modified version of a personal rapid transit (PRT) problem (or personal automated transport (PAT)) that is simulated in Matlab. PRT is a proposed public transport method which offers automated on-demand transportation between any two nodes of the transportation network. The PRT problem of interest is that of autonomous control. This can be likened to one of multi-agent control of many identical agents. Several agents are developed to solve the problem, a rule based agent and BN-agents which use various subsets of the three network updating methods. The experimental results show that the DTA that uses parameter, structure, and utility updating could be a superior solution to agents based only on some subset of those methods

Decision theoretic agent design for personal rapid transit systems

This paper details a learning decision-theoretic intelligent agent designed to solve the problem of guiding vehicles in the context of Personal Rapid Transit (PRT). The intelligent agents are designed using Bayesian Decision Networks. The agents are designed to utilize the known methods of machine learning with Bayesian Networks (BN): parameter learning and structure learning. In addition, a new method of machine learning with BNs, termed utility learning in this paper, is introduced. BN software for Matlab is used to realize the proposed agent. Additional software is written to simulate the PRT problem using various intelligent agents that utilize one or more learning methods

An ergonomics training program for student notebook computer users: Preliminary outcomes of a six-year cohort study

BACKGROUND: The Maine Learning Technology Initiative (MLTI) is a program established in the state of Maine in the United States of America, where all students in 7th and 8th grades are provided with a notebook computer to use at school and at home during the academic year. OBJECTIVE: This study aimed to describe the anthropometric measurements and typing proficiency of a cohort of students in the MLTI. It also investigated the impact of participatory ergonomics education and use of peripheral notebook accessories on their reported musculoskeletal and visual discomfort over the first three years of a six year study. METHODS: This longitudinal study commenced in 2009 with 34 students in 7th grade consenting to participate for six years through the 12th grade. Students received ergonomics education about healthy notebook use, reinforced with web-based resources; and were provided with peripheral notebook accessories including a notebook riser, and external keyboard (split or non-split) and mouse. RESULTS: The use of an external keyboard resulted in a reduction in neck and shoulder pain. Participants self-reported fewer headaches when using an external mouse. Using no external accessories was associated with self-reported back pain. Although other musculoskeletal discomforts decreased over time, the changes were not statistically significant. There was a trend for the reduction of visual symptoms including dry/watery eyes and sore, tired eyes during the study. CONCLUSION: Participatory ergonomics training and use of external devices may have significant health benefits for children involved in notebook programs who have daily exposure to this technology for school and leisure purposes. Internal and external validity of the results were limited by small sample size

Factors associated with spontaneous stone passage in a contemporary cohort of patients presenting with acute ureteric colic. Results from the MIMIC Study (A Multi-centre cohort study evaluating the role of Inflammatory Markers in patients presenting with acute ureteric Colic)

Objectives There is conflicting data on the role of white blood cell count (WBC) and other inflammatory markers in spontaneous stone passage in patients with acute ureteric colic. The aim of the study was to assess the relationship of WBC and other routinely collected inflammatory and clinical markers including stone size, stone position and Medically Expulsive Therapy use (MET) with spontaneous stone passage (SSP) in a large contemporary cohort of patients with acute ureteric colic. Subjects and Methods Multi‐centre retrospective cohort study coordinated by the British Urology Researchers in Surgical Training (BURST) Research Collaborative at 71 secondary care hospitals across 4 countries (United Kingdom, Republic of Ireland, Australia and New Zealand). 4170 patients presented with acute ureteric colic and a computer tomography confirmed single ureteric stone. Our primary outcome measure was SSP as defined by the absence of need for intervention to assist stone passage. Multivariable mixed effects logistic regression was used to explore the relationship between key patient factors and SSP. Results 2518 patients were discharged with conservative management and had further follow up with a SSP rate of 74% (n = 1874/2518). Sepsis after discharge with conservative management was reported in 0.6% (n = 16/2518). On multivariable analysis neither WBC, Neutrophils or CRP were seen to predict SSP, with an adjusted OR of 0.97 [95% CI 0.91 to 1.04, p = 0.38], 1.06 [95% CI 0.99 to 1.13, p = 0.1] and 1.00 [95% CI 0.99 to 1.00, p = 0.17], respectively. Medical expulsive therapy (MET) also did not predict SSP [adjusted OR 1.11 [95% CI 0.76 to 1.61]). However, stone size and stone position were significant predictors. SSP for stones 7mm. For stones in the upper ureter the SSP rate was 52% [95% CI 48 to 56], middle ureter was 70% [95% CI 64 to 76], and lower ureter was 83% [95% CI 81 to 85]. Conclusion In contrast to the previously published literature, we found that in patients with acute ureteric colic who are discharged with initial conservative management, neither WBC, Neutrophil count or CRP help determine the likelihood of spontaneous stone passage. We also found no overall benefit from the use of MET. Stone size and position are important predictors and our findings represent the most comprehensive stone passage rates for each mm increase in stone size from a large contemporary cohort adjusting for key potential confounders. We anticipate that these data will aid clinicians managing patients with acute ureteric colic and help guide management decisions and the need for intervention

Psychosocial impact of undergoing prostate cancer screening for men with BRCA1 or BRCA2 mutations.

OBJECTIVES: To report the baseline results of a longitudinal psychosocial study that forms part of the IMPACT study, a multi-national investigation of targeted prostate cancer (PCa) screening among men with a known pathogenic germline mutation in the BRCA1 or BRCA2 genes. PARTICPANTS AND METHODS: Men enrolled in the IMPACT study were invited to complete a questionnaire at collaborating sites prior to each annual screening visit. The questionnaire included sociodemographic characteristics and the following measures: the Hospital Anxiety and Depression Scale (HADS), Impact of Event Scale (IES), 36-item short-form health survey (SF-36), Memorial Anxiety Scale for Prostate Cancer, Cancer Worry Scale-Revised, risk perception and knowledge. The results of the baseline questionnaire are presented. RESULTS: A total of 432 men completed questionnaires: 98 and 160 had mutations in BRCA1 and BRCA2 genes, respectively, and 174 were controls (familial mutation negative). Participants' perception of PCa risk was influenced by genetic status. Knowledge levels were high and unrelated to genetic status. Mean scores for the HADS and SF-36 were within reported general population norms and mean IES scores were within normal range. IES mean intrusion and avoidance scores were significantly higher in BRCA1/BRCA2 carriers than in controls and were higher in men with increased PCa risk perception. At the multivariate level, risk perception contributed more significantly to variance in IES scores than genetic status. CONCLUSION: This is the first study to report the psychosocial profile of men with BRCA1/BRCA2 mutations undergoing PCa screening. No clinically concerning levels of general or cancer-specific distress or poor quality of life were detected in the cohort as a whole. A small subset of participants reported higher levels of distress, suggesting the need for healthcare professionals offering PCa screening to identify these risk factors and offer additional information and support to men seeking PCa screening

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

System dynamics and control/ Umez-Eronini

xiv, 993 hal.: ill.; 25 cm

System dynamics and control/ Umez-Eronini

xiv, 993 hal.: ill.; 25 cm