University of Sydney

About: University of Sydney is a education organization based out in Sydney, New South Wales, Australia. It is known for research contribution in the topics: Population & Health care. The organization has 61532 authors who have published 187345 publications receiving 6114218 citations. The organization is also known as: Sydney University & USyd.

The orphan human pregnane X receptor mediates the transcriptional activation of CYP3A4 by rifampicin through a distal enhancer module.

Abstract: Cytochrome P-450 3A4 (CYP3A4), the predominant cytochrome P-450 expressed in adult human liver, is subject to transcriptional induction by a variety of structurally unrelated xenobiotics, including the antibiotic rifampicin. The molecular mechanisms underlying this phenomenon are poorly understood. We transfected a human liver-derived cell line (HepG2) with various CYP3A4 -luciferase reporter gene constructs containing a nested set of 5′-deletions of the CYP3A4 5′-flanking region. Rifampicin-inducible transcription of the reporter gene was observed only with the longest construct, which encompassed bases −13000 to +53 of CYP3A4 (3-fold induction). The responsive region was functional regardless of its position or orientation relative to the proximal promoter of CYP3A4 and was capable of conferring rifampicin-inducible expression on a heterologous promoter. Further deletion mutants localized the induction to bases −7836 to −7607. In vitro DNase I footprint analysis of this region revealed four protected sites (FP1, FP2, FP3, and FP4). Two of these sites, FP3 (bases −7738 to −7715) and FP4 (bases −7698 to −7682), overlapped binding motifs for the orphan human pregnane X receptor (hPXR). Cotransfection of responsive constructs with a hPXR expression vector substantially increased the rifampicin-inducibility to ∼50-fold. In addition, the rifampicin-responsive constructs were strongly activated by a range of CYP3A inducers. Finally, we demonstrate cooperativity between elements within the distal enhancer region and cis -acting elements in the proximal promoter of CYP3A4 . Our results provide evidence for the existence of a potent enhancer module, 8 kb distal to the transcription start point, which mediates the transcriptional induction of CYP3A4 by activators of hPXR.

Stated preference analysis of travel choices: the state of practice

Abstract: Stated preference (SP) methods are widely used in travel behaviour research and practice to identify behavioural responses to choice situations which are not revealed in the market, and where the attribute levels offered by existing choices are modified to such an extent that the reliability of revealed preference models as predictors of response is brought into question. This paper reviews recent developments in the application of SP models which add to their growing relevance in demand modelling and prediction. The main themes addressed include a comparative assessment of choice models and preference models, the importance of scaling when pooling different types of data, especially the appeal of SP data as an enriching strategy in the context of revealed preference models, hierarchical designs when the number of attributes make single experiments too complex for the respondent, and ways of accommodating dynamics (i.e. serial correlation and state dependence) in SP modelling.

Simultaneous Localization, Mapping and Moving Object Tracking

Abstract: Simultaneous localization, mapping and moving object tracking (SLAMMOT) involves both simultaneous localization and mapping (SLAM) in dynamic environments and detecting and tracking these dynamic objects. In this paper, a mathematical framework is established to integrate SLAM and moving object tracking. Two solutions are described: SLAM with generalized objects, and SLAM with detection and tracking of moving objects (DATMO). SLAM with generalized objects calculates a joint posterior over all generalized objects and the robot. Such an approach is similar to existing SLAM algorithms, but with additional structure to allow for motion modeling of generalized objects. Unfortunately, it is computationally demanding and generally infeasible. SLAM with DATMO decomposes the estimation problem into two separate estimators. By maintaining separate posteriors for stationary objects and moving objects, the resulting estimation problems are much lower dimensional than SLAM with generalized objects. Both SLAM and moving object tracking from a moving vehicle in crowded urban areas are daunting tasks. Based on the SLAM with DATMO framework, practical algorithms are proposed which deal with issues of perception modeling, data association, and moving object detection. The implementation of SLAM with DATMO was demonstrated using data collected from the CMU Navlab11 vehicle at high speeds in crowded urban environments. Ample experimental results shows the feasibility of the proposed theory and algorithms.