23,580 results for The University of Auckland Library

  • Accelerating the introduction of spectrum sharing using market-based mechanisms

    Beltran, Hector (2016)

    Conference item
    The University of Auckland Library

    Spectrum management needs to be effective, in that spectrum must be allocated to the right uses, and efficient, in that spectrum must be assigned to those that value it the most. Technological advances and demands for further spectrum availability from mobile broadband operators (among others) require spectrum management to timely and firmly incorporate schemes to increase the technical efficiency of spectrum utilisation. One such scheme is spectrum sharing which has the potential to result in higher spectrum utilisation and greater spectrum value. In such context allocation and assignment, two critical functions to manage the spectrum, are also discussed. It is argued that in the course of deciding about allocation and assignment of spectrum, a spectrum authority can and should include market-based mechanisms that incentivise incumbents to share spectrum needed by entrants.

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  • Arming antibodies with DNA cross-linking agents derived from the duocarmycins

    Lu, Guo-Liang; Tercel, M; Giddens, Anna; Lee, H; Bonnet, Muriel; Denny, William; Flygare, JA; Pillow, TA; Safina, BS; Stabenb, LR; Verma, VA; Wei, B (2016-08-28)

    Conference item
    The University of Auckland Library

    Antibody drug conjugates (ADCs) are composed of an antibody covalently linked to a therapeutic agent in such a way that the agent (or ???payload???) is released selectively by antigen-presenting cells. Two ADCs armed with cytotoxic microtubule-binding agents have recently been approved for the treatment of HER2-positive breast cancer and CD30-positive lymphoma, prompting much work on the development of alternative ADCs as anticancer agents. An active area of exploration concerns the search for suitable payloads outside the class of microtubule-binding agents. The duocarmycins are a small group of natural products that alkylate adenine in the minor groove of DNA. They possess several properties that make them attractive as ADC payloads, including high cytotoxic potency, activity against many multidrug-resistant cell lines, and activity against both cycling and non-cycling cells. Simplified and more synthetically accessible variants of the alkylating subunit have been reported which retain the cytotoxic potency of the natural products. This potency can be further enhanced by the preparation of dimeric analogues which cross-link DNA, providing, in some examples, remarkably toxic compounds with IC50s in the fM range. This presentation will report on the synthesis and properties of homo- and heterodimers incorporating duocarmycin analogues, the preparation and antibody-conjugation of drug-linker constructs of the same, and the properties of these new ADC candidates.

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  • Understanding strategies in the Combinatorial Clock Auction: the case of Canada's 700 MHz auction

    Beltran, Hector (2016)

    Conference item
    The University of Auckland Library

    Industry Canada, the authority charged with radio spectrum allocation and assignment in Canada, administered a Combinatorial Clock Auction in 2014 whereby a sizable number of spectrum licenses were awarded to a handful of telecommunications operators to provide 4G cellular service throughout the Canadian provinces. The auction format, the Combinatorial Clock Auction (CCA), is now increasingly replacing the Simultaneous Multiple Round Auction (SMRA) as the preferred method to assign commercial radio spectrum. The CCA has been used in several countries by spectrum authorities to assign spectrum bands for cellular (4G) services and wireless broadband. In its essential design the Canadian CCA consists of two main stages: the Allocation stage and the Assignment stage; in turn the allocation stage is further divided in two: the Clock Rounds and the Supplementary Round. This paper discusses the main features of the CCA and highlights some of the differences with other previously used formats. Next, it uses an extensive repository of data from the results of Canada???s 700 MHz auction in order to analyse the strategic aspects of auction participants' bids occurred during the first stage of the auction, known as the Clock Rounds. Data is publicly available, posted by Industry Canada, and traces every bidder???s demand history throughout the auction represented by the round-to-round demanded bundles and the aggregate bid (bid price) for each bundle. Bidding data also shows a bidder's eligibility and activity levels, two important auction measurements of activity that constrain a bidder's behaviour.

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  • Ultrasound assisted thermal pasteurization of beers with different alcohol levels: inactivation of Saccharomyces cerevisiae ascospores

    Milani, EA; Silva, FVM (2017-04)

    Journal article
    The University of Auckland Library

    The industrial production of beer ends with a process of pasteurization. This study investigated the ultrasound assisted thermal pasteurization of beer or thermosonication (TS), aiming the inactivation of Saccharomyces cerevisiae ascospores, the most resistant form of the yeast. The efficacy of 30 s TS in batch and continuous operation mode at 60, 65, and 70°C was studied. After that the ascospore inactivation in beers was modelled and TS pasteurization conditions recommended. Lastly, the inactivation of S. cerevisiae ascospores in beer by TS vs. thermal processing at 55°C was compared. Ultrasound alone and continuous TS operation were not enough to achieve the minimum beer pasteurization requirement aiming at S. cerevisiae spore inactivation. The TS survival curves were fitted with a Weibull model. TS at 50°C-1.9 min and TS at 55°C-26 s were enough for pasteurization, as opposed to 55°C-38 min thermal process. The results are helpful for designing appropriate thermosonication conditions to pasteurize beer with different alcohol contents and other beverages.

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  • Mere-Zeal, Hyper-Zeal and the Ethical Obligations of Lawyers

    Dare, Tim (2004)

    Journal article
    The University of Auckland Library

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  • The Prevalence of Postgraduate Education in Youth Health Among High School Clinicians and Associated Student Health Outcomes

    Denny, S; Farrant, B; Utter, J; Fleming, T; Bullen, P; Peiris-John, R; Clark, T (2016-11)

    Journal article
    The University of Auckland Library

    Purpose Despite numerous calls to improve training in adolescent health, there is little known about the prevalence or effectiveness of specialized training in adolescent health. Methods A two-stage random sampling cluster design was used to collect nationally representative data from 8,500 students from 91 high schools. Student data were linked to data from a survey of school health clinicians from participating schools on their level of training in youth health. Multilevel models accounting for demographic characteristics of students were used to estimate the association between nurses and physicians training in youth health and health outcomes among students. Results Almost all nurses and physicians reported some training in youth health, either having attended lectures or study days in youth health (n = 60, 80%) or completed postgraduate papers in youth health (n = 13, 17.3%). Students in schools where the nurses and physicians had received postgraduate training in youth health were less likely than students from schools with clinicians having attended lectures or study days in youth health to report emotional and behavior difficulties (11.8 vs. 12.7, p = .002) and binge drinking (19.6% vs. 24.9%, p = .03). There were no significant associations between depressive symptoms, suicide risk, cigarette, marijuana, contraception use, or motor vehicle risk behaviors among students and level of training among clinicians in their schools' health service. Conclusions Postgraduate training in youth health among nurses and physicians in school health services is associated with fewer students reporting mental health difficulties and binge alcohol use. These findings support specialized training in youth health for clinicians working predominantly with young people.

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  • Hongi Hika’s Self-Portrait

    Brown, Deidre (2016-06-01)

    Journal article
    The University of Auckland Library

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  • Multiscale rescaled range analysis of EEG recordings in sevoflurane anesthesia

    Liang, Z; Li, D; Ouyang, G; Wang, Y; Voss, Logan; Sleigh, James; Li, X (2012-04)

    Journal article
    The University of Auckland Library

    OBJECTIVE: The Hurst exponent (HE) is a nonlinear method measuring the smoothness of a fractal time series. In this study we applied the HE index, extracted from electroencephalographic (EEG) recordings, as a measure of anesthetic drug effects on brain activity. METHODS: In 19 adult patients undergoing sevoflurane general anesthesia, we calculated the HE of the raw EEG; comparing the maximal overlap discrete wavelet transform (MODWT) with the traditional rescaled range (R/S) analysis techniques, and with a commercial index of depth of anesthesia - the response entropy (RE). We analyzed each wavelet-decomposed sub-band as well as the combined low frequency bands (HEOLFBs). The methods were compared in regard to pharmacokinetic/pharmacodynamic (PK/PD) modeling, and prediction probability. RESULTS: All the low frequency band HE indices decreased when anesthesia deepened. However the HEOLFB was the best index because: it was less sensitive to artifacts, most closely tracked the exact point of loss of consciousness, showed a better prediction probability in separating the awake and unconscious states, and tracked sevoflurane concentration better - as estimated by the PK/PD models. CONCLUSIONS: The HE is a useful measure for estimating the depth of anesthesia. It was noted that HEOLFB showed the best performance for tracking drug effect. SIGNIFICANCE: The HEOLFB could be used as an index for accurately estimating the effect of anesthesia on brain activity.

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  • Gap junctions modulate seizures in a mean-field model of general anesthesia for the cortex

    Steyn-Ross, ML; Steyn-Ross, DA; Sleigh, James (2012-06)

    Journal article
    The University of Auckland Library

    During slow-wave sleep, general anesthesia, and generalized seizures, there is an absence of consciousness. These states are characterized by low-frequency large-amplitude traveling waves in scalp electroencephalogram. Therefore the oscillatory state might be an indication of failure to form coherent neuronal assemblies necessary for consciousness. A generalized seizure event is a pathological brain state that is the clearest manifestation of waves of synchronized neuronal activity. Since gap junctions provide a direct electrical connection between adjoining neurons, thus enhancing synchronous behavior, reducing gap-junction conductance should suppress seizures; however there is no clear experimental evidence for this. Here we report theoretical predictions for a physiologically-based cortical model that describes the general anesthetic phase transition from consciousness to coma, and includes both chemical synaptic and direct electrotonic synapses. The model dynamics exhibits both Hopf (temporal) and Turing (spatial) instabilities; the Hopf instability corresponds to the slow (≲8 Hz) oscillatory states similar to those seen in slow-wave sleep, general anesthesia, and seizures. We argue that a delicately balanced interplay between Hopf and Turing modes provides a canonical mechanism for the default non-cognitive rest state of the brain. We show that the Turing mode, set by gap-junction diffusion, is generally protective against entering oscillatory modes; and that weakening the Turing mode by reducing gap conduction can release an uncontrolled Hopf oscillation and hence an increased propensity for seizure and simultaneously an increased sensitivity to GABAergic anesthesia.

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  • Pharmacokinetics of dexmedetomidine combined with therapeutic hypothermia in a piglet asphyxia model

    Ezzati, M; Broad, K; Kawano, G; Faulkner, S; Hassell, J; Fleiss, B; Gressens, P; Fierens, I; Rostami, J; Maze, M; Sleigh, James; Anderson, B; Sanders, RD; Robertson, NJ (2014-07)

    Journal article
    The University of Auckland Library

    BACKGROUND: The highly selective α2 -adrenoreceptor agonist, dexmedetomidine, exerts neuroprotective, analgesic, anti-inflammatory and sympatholytic properties that may be beneficial for perinatal asphyxia. The optimal safe dose for pre-clinical newborn neuroprotection studies is unknown. METHODS: Following cerebral hypoxia-ischaemia, dexmedetomidine was administered to nine newborn piglets in a de-escalation dose study in combination with hypothermia (whole body cooling to 33.5°C). Dexmedetomidine was administered with a loading dose of 1 μg/kg and maintenance infusion at doses from 10 to 0.6 μg/kg/h. One additional piglet was not subjected to hypoxia-ischaemia. Blood for pharmacokinetic analysis was sampled pre-insult and frequently post-insult. A one-compartment linear disposition model was used to fit data. Population parameter estimates were obtained using non-linear mixed effects modelling. RESULTS: All dexmedetomidine infusion regimens led to plasma concentrations above those associated with sedation in neonates and children (0.4-0.8 μg/l). Seven out of the nine piglets with hypoxia-ischaemia experienced periods of bradycardia, hypotension, hypertension and cardiac arrest; all haemodynamic adverse events occurred in piglets with plasma concentrations greater than 1 μg/l. Dexmedetomidine clearance was 0.126 l/kg/h [coefficient of variation (CV) 46.6.%] and volume of distribution was 3.37 l/kg (CV 191%). Dexmedetomidine clearance was reduced by 32.7% at a temperature of 33.5°C. Dexmedetomidine clearance was reduced by 55.8% following hypoxia-ischaemia. CONCLUSIONS: Dexmedetomidine clearance was reduced almost tenfold compared with adult values in the newborn piglet following hypoxic-ischaemic brain injury and subsequent therapeutic hypothermia. Reduced clearance was related to cumulative effects of both hypothermia and exposure to hypoxia. High plasma levels of dexmedetomidine were associated with major cardiovascular complications.

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  • Open loop optogenetic control of simulated cortical epileptiform activity

    Selvaraj, P; Sleigh, James; Freeman, WJ; Kirsch, HE; Szeri, AJ (2014-06)

    Journal article
    The University of Auckland Library

    We present a model for the use of open loop optogenetic control to inhibit epileptiform activity in a meso scale model of the human cortex. The meso scale cortical model first developed by Liley et al. (2001) is extended to two dimensions and the nature of the seizure waves is studied. We adapt to the meso scale a 4 state functional model of Channelrhodopsin-2 (ChR2) ion channels. The effects of pulsed and constant illumination on the conductance of these ion channels is presented. The inhibitory cell population is targeted for the application of open loop control. Seizure waves are successfully suppressed and the inherent properties of the optogenetic channels ensures charge balance in the cortex, protecting it from damage.

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  • V. 'For now we see through a glass, darkly': the anaesthesia syndrome

    Sanders, RD; Absalom, A; Sleigh, JW; ConsCIOUS Group (2014-05)

    Journal article
    The University of Auckland Library

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  • Teacher narratives as theorisation of teaching: A Chinese teacher's perspectives on communicative language teaching (CLT)

    Bao, C; Zhang, Lawrence; Dixon, HR (2016)

    Journal article
    The University of Auckland Library

    Teaching as a profession is unique in that all the people who enter the profession have had extensive experience of it, which was built up over many years in classrooms as students. However, the pre-existing set of beliefs about teaching and learning, which were based on, and reinforced by, their own experiences, might cause perplexity for teachers who work in different cultural contexts. How to balance pedagogical principles becomes one of the important considerations for these teachers when faced with the perplexity. This study, therefore, was taken to explore the beliefs of a Chinese language teacher, who was educated in a traditional teaching system (three-centeredness) in Mainland China and was teaching Chinese to speakers of other languages (TCSOL) in New Zealand. It was aimed to unveil how a TCSOL teacher coped with such challenges. Narrative inquiry and thematic analysis were adopted in examining this teacher’s experience. Results show that composite factors impacted this teacher’s beliefs about teaching and learning. The research process and findings are expected to offer some implications for fostering effective TCSOL teachers’ professional development.

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  • Re: Is there an alternative to centralization for pancreatic resection in New Zealand?

    Windsor, JA; Pandanaboyana, S; Bartlett, ASJR (2016-09)

    Journal article
    The University of Auckland Library

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  • Carbon dioxide insufflation deflects airborne particles from an open surgical wound model

    Kokhanenko, P; Papotti, G; Cater, John; Lynch, AC; van der Linden, JA; Spence, Callum (2017-01)

    Journal article
    The University of Auckland Library

    Background Surgical site infections remain a significant burden on healthcare systems and may benefit from new countermeasures. Aim To assess the merits of open surgical wound CO2 insufflation via a gas diffuser to reduce airborne contamination, and to determine the distribution of CO2 in and over a wound. Methods An experimental approach with engineers and clinical researchers was employed to measure the gas flow pattern and motion of airborne particles in a model of an open surgical wound in a simulated theatre setting. Laser-illuminated flow visualizations were performed and the degree of protection was quantified by collecting and characterizing particles deposited in and outside the wound cavity. Findings The average number of particles entering the wound with a diameter of 95% and diminished rapidly above the wound to an atmospheric level (∼0%) at a height of 25 mm. Conclusion Airborne particles were deflected from entering the wound by the CO2 in the cavity akin to a protective barrier. Insufflation of CO2 may be an effective means of reducing intraoperative infection rates in open surgeries.

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  • Additive Manufacturing of High Resolution Embedded Electronic Systems

    Wasley, T; Li, J; Ta, D; Shephard, J; Stringer, Jonathan; Smith, P; Esenturk, E; Connaughton, C; Kay, R (2016)

    Conference item
    The University of Auckland Library

    Additive Manufacturing (AM) processes can facilitate the rapid iterative product development of electronic devices by optimising their design and functionality. This has been achieved by combining two additive manufacturing processes with conventional surface mount assembly to generate high resolution embedded multilayer electronic circuits contained within a 3D printed polymer part. Bottom-up DLP Stereolithography and material dispensing of isotropic conductive adhesives have been interleaved to deposit microscale features on photopolymer substrates. The material dispensing process has demonstrated the high density deposition of conductors attaining track widths of 134μm and produced interconnects suitable for directly attaching bare silicon die straight to the substrate. Interconnects down to a diameter of 149μm at a pitch of 457μm have been realized. In addition, this research developed a novel method for producing high aspect ratio z-axis connections. These were simultaneously printed with the circuit and component interconnects by depositing through-layer pillars with a maximum aspect ratio of 3.81. Finally, a method to accurately embed the packaged circuit layer within the printed part has been employed using bottom-up stereolithography.

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  • A theoretical and experimental investigation of roof flexibility on internal and net roof pressure dynamics in low-rise buildings with a dominant opening’

    Guha, TK; Sharma, Rajnish; Richards, Peter (2012)

    Journal article
    The University of Auckland Library

    A theoretical and experimental study of the effect of roof flexibility on the dynamics of internal and net roof pressure is reported in thsi paper. A two-degree-of-freedom dynamic model and its simplified counterpart, the single-degree-of-freedom quasi-static model is sued for theoretical analysis. As an illustrative example, admittance and spectra of internal and net roof pressure is presented for a medium-sized industrial building with different roof flexibilities using these models. Complementary wind tunnel investigations using a felixible Styrofoam roof are carried out to validate the model predictions. Additionally, effect of the dominant opening size and wind direction (i.e. angle of attack) on internal pressure for the flexible roof is experimentally investigated in the wind tunnel with a comparison to those for a rigid roof model.

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  • The significance of powder breakdown during conveying within industrial milk powder plants

    Boiarkina, Irina; Sang, C; Depree, N; Prince-Pike, Arrian; Yu, Wei; Wilson, DI; Young, BR (2016)

    Journal article
    The University of Auckland Library

    Instant whole milk powder is designed to rapidly dissolve in water, which depends on the particle size distribution (PSD). The fragile powder exiting the dryer is conveyed for packing which breaks down the particles, worsening the dissolution properties. This work investigated the effect of conveying on the final functional properties using two industrial plants with differing transport systems; a pneumatic system and bucket elevator. It was expected that the plant with the bucket elevator consistently produced powder with superior dissolution due to lower breakdown during transport. This was evaluated using the change in PSD. It was found that the plant with the bucket elevator had at least as large a change in the median particle size as the plant with the pneumatic transport system, contrary to the expectation. However, the plant with the bucket elevator had an initially larger particle size, and so the percentage of fine particles that negatively impact dissolution, remained low post transport. When quantified using the change in bulk density, having an initially low bulk density compensated for large increases in bulk density during conveying and powder with lower bulk density pre-transport showed better wettability post transport. Thus in order to produce powder with the desired functionalities the focus should be on improving the initial agglomeration and generating larger particles and lower bulk density pre-transport, as opposed to optimising the powder transport.

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  • Acoustic Echo and Noise Canceller for Personal Hands-Free Video IP Phone

    Fukui, M; Shimauchi, S; Hioka, Yusuke; Nakagawa, A; Hanead, Y (2016-11)

    Journal article
    The University of Auckland Library

    This paper presents implementation and evaluation of a proposed acoustic echo and noise canceller (AENC) for videotelephony-enabled personal hands-free Internet protocol (IP) phones. This canceller has the following features: noise-robust performance, low processing delay, and low computational complexity. The AENC employs an adaptive digital filter (ADF) and noise reduction (NR) methods that can effectively eliminate undesired acoustic echo and background noise included in a microphone signal even in a noisy environment. The ADF method uses the step-size control approach according to the level of disturbance such as background noise; it can minimize the effect of disturbance in a noisy environment. The NR method estimates the noise level under an assumption that the noise amplitude spectrum is constant in a short period, which cannot be applied to the amplitude spectrum of speech. In addition, this paper presents the method for decreasing the computational complexity of the ADF process without increasing the processing delay to make the processing suitable for real-time implementation. The experimental results demonstrate that the proposed AENC suppresses echo and noise sufficiently in a noisy environment; thus, resulting in natural-sounding speech.

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  • Simplified windborne debris equations in strong winds

    Richards, Peter (2014-02-01)

    Journal article
    The University of Auckland Library

    Approximate solutions are derived for the flight of compact wind borne debris in strong winds. The relevant characteristics of the piece of debris are combined together into the ballistic coefficient. The solutions are put into a non-dimensional form which leads to a set of universal silutions which can be plotted in a manner such that one set of graphs applies to all sizes of debris and wind strength situations. The derived equations are used to show that most common types of debris can easily achieve 40% of the wind speed and in some cases can reach much higher levels.

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