6,596 results for Conference item

  • Challenges in Short Text Classification: The Case of Online Auction Disclosure

    Li, Yichen; Tripathi, Arvind; Srinivasan, Ananth (2016)

    Conference item
    The University of Auckland Library

    Text classification is an important research problem in many fields. We examine a special case of textual content namely, short text. Examples of short text appear in a number of contexts such as online reviews, chat messages, twitter feeds, etc. In this research, we examine short text for the purpose of classification in internet auctions. The ???ask seller a question??? forum of a large horizontal intermediary auction platform is used to conduct this research. We describe our approach to classification by examining various solution methods to the problem. The unsupervised K-Medoids clustering algorithm provides useful but limited insights into keywords extraction while the supervised Na??ve Bayes algorithm successfully achieves on average, around 65% classification accuracy. We then present a score assigning approach to this issue which outperforms the other two methods. Finally, we discuss how our approach to short text classification can be used to analyse the effectiveness of internet auctions.

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  • Secondary tongue retraction in Arabic emphatics: An acoustic study

    Al-Tairi, Hamed; Watson, Catherine; Brown, Jason (2016-12-06)

    Conference item
    The University of Auckland Library

    This study provides an acoustic investigation of the secondary articulation of Arabic emphatic sounds. The study observed seven male Arabic speakers from four dialects to investigate F1 and F2 of /a:/, /i:/ and /u:/ in emphatic and non-emphatic environments in 501 monosyllabic words. A repeated-measures ANOVA was conducted to examine the main and interaction effects of emphasis with consonant, vowel, and position factors. Regardless of the inter-subject variability, the Gaussian classifi- cation model shows limited differences among subjects. Index Terms: Arabic, dialect, emphatics, formants

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  • Tissue Specific Simulations of Interstitial Cells of Cajal Networks Using Unstructured Meshes

    Sathar, Shameer; Trew, Mark; Cheng, Leo (2015-01-01)

    Conference item
    The University of Auckland Library

    Gastrointestinal motility is facilitated by specialized pacemaker cells called Interstitial Cells of Cajal (ICC). ICC play a critical role in coordinating normal motility and its degradation in the gastrointestinal tract is associated with many functional motility disorders. Nonetheless, the degree of degradation and associated clinical impact remains unclear. Continuum modeling frameworks offers a virtual mean to simulate the electrical activity, and analyze the ICC activity in both normal and diseased states. Confocal images of the ICC networks were obtained from the intestine of normal mice. In this study, a new approach is presented where meshes of ICC networks were generated using a Delaunay triangulation and used to solve finite-element based reaction-diffusion equations describing gastrointestinal electrophysiology. The electrical activity was simulated on the ICC network and solutions were compared to those of a regular mesh based on individual pixel locations. The simulation results showed the proposed approach to be approximately 80% more efficient than a pixel-based mesh. The difference in activation time for the entire network between the different methods was observed to be around 4% (about 20 ms). The proposed approach will enable efficient examination of the ICC slow wave activity in larger networks and for longer temporal duration that has been previously impossible. This will provide valuable insights relating ICC degradation to gastrointestinal motility disorders.

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  • Postoperative ileus: mechanisms and future directions for research

    Vather, R; O'Grady, Gregory; Bissett, Ian; Dinning, PG (2014-05)

    Conference item
    The University of Auckland Library

    Postoperative ileus (POI) is an abnormal pattern of gastrointestinal motility characterized by nausea, vomiting, abdominal distension and/or delayed passage of flatus or stool, which may occur following surgery. Postoperative ileus slows recovery, increases the risk of developing postoperative complications and confers a significant financial load on healthcare institutions. The aim of the present review is to provide a succinct overview of the clinical features and pathophysiological mechanisms of POI, with final comment on selected directions for future research.Terminology used when describing POI is inconsistent, with little differentiation made between the obligatory period of gut dysfunction seen after surgery ('normal POI') and the more clinically and pathologically significant entity of a 'prolonged POI'. Both normal and prolonged POI represent a fundamentally similar pathophysiological phenomenon. The aetiology of POI is postulated to be multifactorial, with principal mediators being inflammatory cell activation, autonomic dysfunction (both primarily and as part of the surgical stress response), agonism at gut opioid receptors, modulation of gastrointestinal hormone activity and electrolyte derangements. A final common pathway for these effectors is impaired contractility and motility and gut wall oedema. There are many potential directions for future research. In particular, there remains scope to accurately characterize the gastrointestinal dysfunction that underscores an ileus, development of an accurate risk stratification tool will facilitate early implementation of preventive measures and clinical appraisal of novel therapeutic strategies that target individual pathways in the pathogenesis of ileus warrant further investigation.

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  • The Development of Hypoxia-selective PERK Inhibitor Prodrugs

    Liew, Lydia; Wong, Way; Singleton, Dean; Jamieson, Stephen; Flanagan, Jack; Koumenis, C; Hay, Michael (2017-04-29)

    Conference item
    The University of Auckland Library

    The Development of Hypoxia-selective PERK Inhibitor Prodrugs Lydia P. Liew PhD1, Way W. Wong MSc1, Dean C. Singleton PhD1, Stephen M.F. Jamieson PhD1, Jack U. Flanagan PhD1, Costas Koumenis PhD2, Michael P. Hay PhD1. 1Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Auckland, New Zealand. 2Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. Purpose The unfolded protein response (UPR) is initiated in cells under endoplasmic reticulum (ER) stress. Within the tumor microenvironment, accumulation of unfolded or misfolded proteins results in a stress stimuli which is sensed by chaperone proteins in the ER to activate protein kinase R-like ER kinase (PERK) as well as inositol-requiring enzyme 1 (IRE-1) and activating transcription factor-6 (ATF-6). Under hypoxia-induced stress, the UPR is primarily mediated via the PERK pathway. Upon activation, PERK signals responses to alleviate cellular stress; in the event where these stresses cannot resolved, the cells enter apoptosis. Potent and selective PERK inhibitors (PERKi) have been developed, and leading examples (GSK2606414 and GSK2656157) demonstrate tumor growth inhibition in human tumor xenograft models. However, these PERKi also exhibit mechanism-based normal tissue toxicity. Although GSK???157 was advanced to Phase I studies, no further studies have been conducted, presumably because of an inadequate therapeutic index. In order to overcome this normal tissue toxicity, we propose to engender tumor selectivity by using a hypoxia-activated prodrug (HAP) approach. We envision inactive, non-toxic HAPs of PERK inhibitors will undergo selective activation in hypoxic tumour tissue to release the active drug. Methods Examination of the binding mode of GSK???414 in the active site of PERK (pdb4g31) highlighted several critical interactions involved in drug binding. We explored two design approaches (i) blocking interaction with the kinase ??-strand hinge; and (ii) blocking interaction with the lipophilic specificity pocket. We prepared a series of analogues based on GSK???414 and the corresponding HAP analogues. We measured the stability of the prodrugs and their ability to fragment following reduction. We determined the ability of the analogues to inhibit phosphorylation of EIF2AK3 and explored their effect on HCT116 cells under oxic and anoxic conditions. Results Our attempts to design effective prodrugs that would disrupt the kinase ??-strand hinge binding were unsuccessful. Model prodrugs did not demonstrate fragmentation after reduction and the presence of the prodrug unit precluded the synthesis of fully functional PERKi. In contrast, we were able to exploit structure-based design to successfully prepare new indolyl-pyrrolo[2,3-d]pyrimidine analogues with modifications in the lipophilic specificity domain designed to accommodate HAP triggers. The structure-activity relationships (SAR) for PERK inhibition were determined and nitroimidazole-based HAPs were prepared. The purity and stability of the HAPs were tested in biological media. The HAPs fragmented to release the effector following reductive activation in vitro. Conclusions While direct preparation of HAPs of the GSK clinical candidate was not possible, modification at the specificity pocket domain led to potent PERKi suitable for a HAP approach. The corresponding HAPs were significantly deactivated as PERKi and underwent reductive activation to release effector. Their biological evaluation and development continues. We are currently investigating an expanded series of PERKi, and are optimising trigger and linker options for our inhibitors.

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  • Exploring Text To Speech Synthesis in Non-Standard Languages

    James, Jesin; Watson, Catherine; Gopinath, DP (2016)

    Conference item
    The University of Auckland Library

    The development of Text to Speech synthesis systems as part of the Human Language Technology is a dominating research field in the present age. Languages are the backbone of every culture and developing technologies in every language is a basic requirement for users. Technology development focusing on the standard languages is a discouraging trend for many users who are not well-versed in these languages, but are in need of assistive technology. This paper focusses on the challenges in developing speech systems for non-standard languages, in light of a TTS development work in Malayalam language (non-standard language used in South India).

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  • Continuous Spoken Emotion Recognition Based on Time-Frequency Features of the Glottal Pulse Signal within Stressed Vowels

    Tian, L; Watson, Catherine (2016)

    Conference item
    The University of Auckland Library

    In speech production, emotional cues can be detected via three main aspects: excitation source, vocal tract and prosodic pattern. This paper addressed the first one, extracting six time and frequency related features from glottal pulse signals, transformed from stressed vowels. Four sustained vowels incorporating five regular emotions, which were selected from sentence recordings of the Berlin emotional speech database were investigated. The effectiveness of those glottal pulse features towards emotion recognition was proven through double round Robin quadratic classification in both singlegender and cross-gender stages, reaching average overall hitrate of 63%, 64% and 53% for male, female and cross-gender respectively.

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  • Tongue Retraction in Arabic: An Ultrasound Study

    Al-Tairi, Hamed; Brown, Jason; Watson, Catherine; Gick, B (2017-05-01)

    Conference item
    The University of Auckland Library

    A common analysis for Arabic emphatics and pharyngeals posits that their commonalities are due to the shared feature [RTR]. This, however, does not account for some phonological processes, and does not reflect their phonetic representation. This study provides ultrasound evidence that emphatics and pharyngeals do not exhibit a similar retraction of the tongue. Results indicate that while tongue retraction for the emphatics is characterized with simultaneous tongue dorsum and root retraction, the pharyngeals lower the tongue dorsum. Unlike the pharyngeals, the tongue root retraction of the emphatics and uvulars is always posterior to the tongue root position of the inter-speech posture. Such a consistent and significant displacement confirms that [RTR] is an active feature for the emphatics and uvulars. This is also evident from the retraction of following low vowels triggered by the emphatics and uvulars. These phonetic findings suggest that the pharyngeals and emphatics have different phonological representations.

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  • Direct and indirect effects of monosodium urate crystals on osteocyte cell viability and gene expression; Is there a role for osteocytes in erosive gout?

    Chhana, Ashika; Pool, Bregtina; Tay, M; Callon, Karen; Musson, David; Naot, Dorit; Gamble, G; Cornish, Jillian; Dalbeth, N (2017-05)

    Conference item
    The University of Auckland Library

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  • Advanced imaging assessment of tophaceous gout: Comparison of dual-energy CT and magnetic resonance imaging with anatomical pathology

    Chhana, Ashika; Doyle, Anthony; Sevao, A; Amirapu, Satya; Riordan, P; Dray, Michael; McGlashan, Susan; Cornish, Jillian; Dalbeth, Nicola (2017-05)

    Conference item
    The University of Auckland Library

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  • Investigating Parylene-HT as a Substrate for Human Cell Patterning

    Raos, BJ; Graham, ES; Murray, AF; Simpson, MC; Unsworth, CP (2016)

    Conference item
    The University of Auckland Library

    We demonstrate, for the first time, how parylene-HT on SiO2 substrates can be used as a human cell patterning platform. We demonstrate this platform with hNT astrocytes, derived from the human NTera2.D1 cell line. We show how hNT astrocytes are attracted to Parylene-HT and repelled by the SiO2 and are shown to adopt a similar morphology as that attained on standard tissue culture polystyrene. Furthermore, parylene-HT was capable of patterning the astrocytes achieving a ratio of 8:1 for cells on parylene compared to SiO2. Thus, as parylene-HT has similar physical properties to parylene-C with the addition of UV and thermal resistance, parylene-HT represents a desirable alternative substrate for human cell patterning.

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  • Computational modelling of self-centering precast concrete walls

    Watkins, Jonathan; Henry, Richard; Sritharan, S (2013)

    Conference item
    The University of Auckland Library

    Existing predictive models of self-centering precast concrete walls with posttensioning are generally computationally expensive. While simplistic models have a low computational cost, they are generally incapable of simulating cyclic behavior of these walls. Hence, a new computational model suitable for characterizing cyclic response of selfcentering precast concrete walls was developed with emphasis on accuracy and computational efficiency. The proposed model consisted of a bed of truss elements at the base of wall where the rocking response is expected, truss elements for the post-tensioning tendons, and an elastic beam-column element for the wall panel. To ensure the accuracy of wall response, including the quantification of residual displacements, a robust concrete hysteresis model was required in the analysis. The proposed modelling technique was verified against five experimental tests completed on self-centering precast concrete walls. In all cases, the model accurately captured the overall cyclic behavior and residual displacements of the self-centering precast concrete wall. Furthermore, the models also satisfactorily captured several local response parameters, including the wall uplift, neutral axis depth, lateral drifts at which concrete spalling and crushing occurred, and post-tensioning force for both loading and unloading cycles at all ranges of lateral drifts.

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  • Dietary Nitrate Supplementation Improves Rowing Performance In Highly Trained Rowers

    Braakhuis, Andrea; Bond, Hannah; Morton, Lillian (2012-05-01)

    Conference item
    The University of Auckland Library

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  • Understanding the transitions of social life in public spaces in Indonesian cities. A comparative study on the ???urban inversion??? of the Integrated Retail Centres of Surabaya.

    Manfredini, Manfredo; Jenner, Gordon; Jusmartinah, Raja; Litterick, P (2014)

    Conference item
    The University of Auckland Library

    The rapid numerical and dimensional growth of malls in Indonesian urban areas is having a deep impact on the social life of urban communities, providing new public spaces rich in amenities, safe and climatically comfortable. The success of these structures also relies on their effective provision of very attractive modern environments with clean, organized and controlled environments that offer an alternative to the traditional public open spaces of larger Indonesian cities, which have serious problems of air quality, acoustic pollution, walkability and thermal comfort. In the city of Surabaya ??? the second largest Indonesian conurbation ??? the construction of 28 large mall complexes during the last 10 years has profoundly changed the life of its main urban units: the kampongs. The new developments have also benefited from the support of both local and central authorities, through programmes like the ???Surabaya Shopping Festival,??? an annual event organised by the Tourism Promotion Board of Surabaya. Investigating the urban condition of Surabaya, this paper seeks to understand the continuing transition of social life occurring in urban public space. It foregrounds the substantial shift of people???s everyday practices from traditional publicly owned urban places of social aggregation (streets, open spaces, markets halls) to privately owned places of consumption (mall and entertainment complexes). The paper reports on the first phases of the research; the literature review and the preliminary analysis on the condition and development of malls in Surabaya. The analysis is a comparative research on a selected sample of malls that focuses on two aspects; the structural organization and spatial configuration. The investigation of structural organization of the selected malls is based on empirical research and speculates on the effects of the ???introversion??? of the public space operated by the mall system. It considers structural factors like size, articulation and number of commercial and non-commercial activities, and availability of public services. The study of spatial configuration explores the morphological aspects of the urban inversion operated by the malls, elaborating information on the structure and syntax of the spaces of the selected complexes in relation to the city. In the final discussion, the paper proposes a critical interpretation of the occurring transition in the social life of public spaces, highlighting the most critical aspects emerging in the new architecture of ???enclosures.???

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  • Look at the Driver, Look at the Road: No Distraction! No Accident!

    Rezaei, Mahdi; Klette, Reinhard (2014)

    Conference item
    The University of Auckland Library

    The paper proposes an advanced driver-assistance system that correlates the driver's head pose to road hazards by analyzing both simultaneously. In particular, we aim at the prevention of rear-end crashes due to driver fatigue or distraction. We contribute by three novel ideas: Asymmetric appearance-modeling, 2D to 3D pose estimation enhanced by the introduced Fermat-point transform, and adaptation of Global Haar (GHaar) classifiers for vehicle detection under challenging lighting conditions. The system defines the driver's direction of attention (in 6 degrees of freedom), yawning and head-nodding detection, as well as vehicle detection, and distance estimation. Having both road and driver's behaviour information, and implementing a fuzzy fusion system, we develop an integrated framework to cover all of the above subjects. We provide real-time performance analysis for real-world driving scenarios.

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  • Assessing the rocking response of unreinforced masonry frames in historical New Zealand structures

    Knox, Charlotte; Ma, Tsun Ming Quincy; Ingham, Jason (2009)

    Conference item
    The University of Auckland Library

    The signing of the Treaty of Waitangi in 1840 indentified New Zealand as a British colony. The subsequent influx of British migrants to New Zealand saw the introduction of colonial settlements modelled on the structure of British society. In the late 1800's the comparative absence of knowledge, with respect to the performance of unreinforced masonry (URM) during earthquakes, left unreinforced masonry as the unsurpassed choice for construction of New Zealand's commercial and monumental structures in the rapidly expanding urban centres nationwide. During the 1931 Hawke's Bay Earthquake URM construction was repeatedly proven to perform unsatisfactorily, resulting in a rapid decline in popularity and subsequent prohibition of use in 1965. Its prevalence throughout New Zealand's historic building stock dating between 1880 and the 1935, has lead to the New Zealand government issuing an act effectively requiring all URM buildings to be assessed and seismically retrofitted accordingly.Accurate analysis of the structural response of unreinforced masonry buildings to earthquake loading is essential to the design of efficient and effective seismic retrofit interventions. Five typical masonry frames which are representative of the over 3500 URM buildings found around New Zealand are reported. These five frames include one, two, three and six storey buildings as well as row and stand alone type buildings. International research indicates that the geometric properties of the frame significantly control the type of energy dissipation method adopted by the structure.

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  • Communicating, interpreting, and executing high-level instructions for human-robot interaction

    Trivedi, N; Langley, Patrick; Schermerhorn, P; Scheutz, M (2011)

    Conference item
    The University of Auckland Library

    In this paper, we address the problem of communicating, interpreting, and executing complex yet abstract instructions to a robot team member. This requires specifying the tasks in an unambiguous manner, translating them into operational procedures, and carrying out those procedures in a persistent yet reactive manner. We report our response to these issues, after which we demonstrate their combined use in controlling a mobile robot in a multi-room office setting on tasks similar to those in search-and-rescue operations. We conclude by discussing related research and suggesting directions for future work.

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  • Iterative semi-global matching for robust driver assistance systems

    Hermann, S; Klette, Reinhard (2013)

    Conference item
    The University of Auckland Library

    Semi-global matching (SGM) is a technique of choice for dense stereo estimation in current industrial driver-assistance systems due to its real-time processing capability and its convincing performance. In this paper we introduce iSGM as a new cost integration concept for semi-global matching. In iSGM, accumulated costs are iteratively evaluated and intermediate disparity results serve as input to generate semi-global distance maps. This novel data structure supports fast analysis of spatial disparity information and allows for reliable search space reduction in consecutive cost accumulation. As a consequence horizontal costs are stabilized which improves the robustness of the matching result. We demonstrate the superiority of this iterative integration concept against a standard configuration of semi-global matching and compare our results to current state-of-the-art methods on the KITTI Vision Benchmark Suite.

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  • Logical Foundations of Possibilistic Keys

    Koehler, H; Leck, U; Link, Sebastian; Prade, H (2014-09)

    Conference item
    The University of Auckland Library

    Possibility theory is applied to introduce and reason about the fundamental notion of a key for uncertain data. Uncertainty is modeled qualitatively by assigning to tuples of data a degree of possibility with which they occur in a relation, and assigning to keys a degree of certainty which says to which tuples the key applies. The associated implication problem is characterized axiomatically and algorithmically. It is shown how sets of possibilistic keys can be visualized as possibilistic Armstrong relations, and how they can be discovered from given possibilistic relations. It is also shown how possibilistic keys can be used to clean dirty data by revising the belief in possibility degrees of tuples.

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  • Polypills for high risk patients: Results of a New Zealand randomised controlled trial

    Selak, Vanessa; Elley, Carolyn; Crengle, S; Wadham, Angela; Rafter, N; Bullen, Christopher (2014)

    Conference item
    The University of Auckland Library

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