24,386 results for Journal article

  • Inference on population size in binomial detectability models

    Fewster, Rachel; Jupp, PE (2009)

    Journal article
    The University of Auckland Library

    Many models for biological populations, including simple mark-recapture models and distance sampling models, involve a binomially distributed number, n, of observations x1, . . . , xn on members of a population of size N. Two popular estimators of (N, ??), where ?? is a vector parameter, are the maximum likelihood estimator (N?? , ???? ) and the conditional maximum likelihood estimator (N?? c, ???? c) based on the conditional distribution of x1, . . . , xn given n. We derive the largeN asymptotic distributions of (N?? , ???? ) and (N?? c, ???? c), and give formulae for the biases of log N?? and log N?? c. We show that the difference N?? c ??? N?? is, remarkably, of order 1 and we give a simple formula for the leading part of this difference. Simulations indicate that in many cases this formula is very accurate and that con???dence intervals based on the asymptotic distribution have excellent coverage. An extension to product-binomial models is given.

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  • Beyond technicism: towards ???Being??? and ???knowing in an intra- active pedagogy

    Roder, Howard (2011)

    Journal article
    The University of Auckland Library

    In this paper I consider the theme of technology and its influence on how we come to know possibilities in an increasingly fluid, uncertain world. The argument is made that we are not always aware of how technology, linked with the project of modernity, linear progress, certainty and the scientific method, has contributed to an overly instrumental and technicist view of the complex endeavour of early childhood education in contemporary times. If modernity has produced categorizations and separation through binary divides such as theory/practice, adult/child, individual/group, matter/discourse then the project of postmodernity blurs these divisions and draws attention back to their complexity. Understanding how the overarching mood of technology has contributed to these divides and their part in supporting hegemonic technicist views of practice, leads us to question how might this be turned? More specifically I consider alternative views, involving digital technologies and pedagogical documentation that afford new spaces for ???border crossing??? (Dahlberg & Moss, 2005, p. 23), as a means for reflecting and revealing our taken for granted assumptions.

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  • Controlling of systemic absorption of gliclazide through incorporation into alginate beads

    Al-Kassas, Raida; Al-Gohary, OMN; Al-Faadhel, MM (2007)

    Journal article
    The University of Auckland Library

    This work investigates preparation of biodegradable beads with alginate polymer by ionotropic gelation method to take the advantages of the swelling and mucoadhesive properties of alginate beads for improving the oral delivery of the antidiabetic agent gliclazide. It demonstrates that the ionic gelation of alginate molecules offers a flexible and easily controllable process for manipulating the characteristics of the beads which are important in controlling the release rate and consequently the absorption of gliclazide from the gastrointestinal tract. Variations in polymer concentration, stirring speed, internal phase volume and the type of surfactant in the external phase were examined systemically for their effects on the particle size, incorporation efficiency and flow properties of the beads. The swelling behavior was strongly dependent on the polymer concentration in the formulations and the pH of the medium. The in vitro release experiments revealed that the swelling is the main parameter controlling the release rate of gliclazide from the beads. In vivo studies on diabetic rabbits showed that the hypoglycemic effect induced by the gliclazide loaded alginate beads was significantly greater and more prolonged than that induced by the marketed conventional gliclazide tablet (Gliclazide??). The results clearly demonstrated the ability of the system to maintain tight blood glucose level and improved the patient compliance by enhancing, controlling and prolonging the systemic absorption of gliclazide.

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  • The influence of femoral internal and external rotation on cartilage stresses within the patellofemoral joint.

    Besier, Thor; Gold, GE; Delp, SL; Fredericson, M; Beaupr??, GS (2008-12)

    Journal article
    The University of Auckland Library

    Internal and external rotation of the femur plays an important role in defining the orientation of the patellofemoral joint, influencing contact areas, pressures, and cartilage stress distributions. The purpose of this study was to determine the influence of femoral internal and external rotation on stresses in the patellofemoral cartilage. We constructed finite element models of the patellofemoral joint using magnetic resonance (MR) images from 16 volunteers (8 male and 8 female). Subjects performed an upright weight-bearing squat with the knee at 60 degrees of flexion inside an open-MR scanner and in a gait laboratory. Quadriceps muscle forces were estimated for each subject using an electromyographic-driven model and input to a finite element analysis. Hydrostatic and octahedral shear stresses within the cartilage were modeled with the tibiofemoral joint in a "neutral" position and also with the femur rotated internally or externally by 5 degrees increments to +/-15 degrees . Cartilage stresses were more sensitive to external rotation of the femur, compared with internal rotation, with large variation across subjects. Peak patellar shear stresses increased more than 10% with 15 degrees of external rotation in 75% of the subjects. Shear stresses were higher in the patellar cartilage compared to the femoral cartilage and patellar cartilage stresses were more sensitive to femoral rotation compared with femoral cartilage stress. Large variation in the cartilage stress response between individuals reflects the complex nature of the extensor mechanism and has clinical relevance when considering treatment strategies designed to reduce cartilage stresses by altering femoral internal and external rotation.

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  • The zebrafish lysozyme C promoter drives myeloid-specific expression in transgenic fish

    Hall, Christopher; Flores, Maria; Storm, Thilo; Crosier, Kathryn; Crosier, Philip (2007)

    Journal article
    The University of Auckland Library

    Background: How different immune cell compartments contribute to a successful immune response is central to fully understanding the mechanisms behind normal processes such as tissue repair and the pathology of inflammatory diseases. However, the ability to observe and characterize such interactions, in real-time, within a living vertebrate has proved elusive. Recently, the zebrafish has been exploited to model aspects of human disease and to study specific immune cell compartments using fluorescent reporter transgenic lines. A number of blood-specific lines have provided a means to exploit the exquisite optical clarity that this vertebrate system offers and provide a level of insight into dynamic inflammatory processes previously unavailable. Results: We used regulatory regions of the zebrafish lysozyme C (lysC) gene to drive enhanced green fluorescent protein (EGFP) and DsRED2 expression in a manner that completely recapitulated the endogenous expression profile of lysC. Labeled cells were shown by coexpression studies and FACS analysis to represent a subset of macrophages and likely also granulocytes. Functional assays within transgenic larvae proved that these marked cells possess hallmark traits of myelomonocytic cells, including the ability to migrate to inflammatory sources and phagocytose bacteria. Conclusion: These reporter lines will have utility in dissecting the genetic determinants of commitment to the myeloid lineage and in further defining how lysozyme-expressing cells participate during inflammation.

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  • A question of balance: Prioritizing public health responses to harm from gambling

    Adams, Peter; Raeburn, JM; De Silva, K (2009)

    Journal article
    The University of Auckland Library

    To provide an overview on the nature and importance of public health approaches to the global expansion of commercial gambling. Method Three key areas of public health activity are examined: harm minimization, health promotion and the political determinants for change. Findings The rapid proliferation of gambling experienced in many countries is driven by the commercial development of new products orientated around continuous and rapid mass consumption. This is particularly the case with ongoing re???nements to electronic gambling machines and the development of new gambling technologies using the internet and mobile telephones. So far responses to negative impacts have, on the whole, focused upon individualized treatment interventions. A public health approach to gambling offers a broad range of strategies to tackle the wider implications of gambling expansion: harm reduction provides evidence-based strategies for managing identi???able harm; health promotion focuses upon communities building their capacity, knowledge and resilience with regard to the attractions of gambling, and action on the political determinants sets out to increase the accountability and reduce the con???icts of interest that in???uence government resolve in managing their gambling environments. Conclusion In this new environment of mass consumption, efforts in developing treatment responses to problem gambling need to be balanced with, at least, equal efforts in developing public health responses. With the expansion of commercial gambling occurring globally, international agencies could play a critical role in supporting public health initiatives

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  • Genome-wide association study identifies variants at CSF1, OPTN and TNFRSF11A as genetic risk factors for Paget's disease of bone.

    Albagha, OM; Visconti, MR; Alonso, N; Langston, AL; Cundy, Timothy; Dargie, R; Dunlop, MG; Fraser, WD; Hooper, MJ; Isaia, G; Nicholson, GC; del Pino Montes, J; Gonzalez-Sarmiento, R; di Stefano, M; Tenesa, A; Walsh, JP; Ralston, SH (2010-06)

    Journal article
    The University of Auckland Library

    Paget's disease of bone (PDB) is a common disorder with a strong genetic component characterized by focal increases in bone turnover, which in some cases is caused by mutations in SQSTM1. To identify additional susceptibility genes, we performed a genome-wide association study in 750 individuals with PDB (cases) without SQSTM1 mutations and 1,002 controls and identified three candidate disease loci, which were then replicated in an independent set of 500 cases and 535 controls. The strongest signal was with rs484959 on 1p13 near the CSF1 gene (P = 5.38 x 10(-24)). Significant associations were also observed with rs1561570 on 10p13 within the OPTN gene (P = 6.09 x 10(-13)) and with rs3018362 on 18q21 near the TNFRSF11A gene (P = 5.27 x 10(-13)). These studies provide new insights into the pathogenesis of PDB and identify OPTN, CSF1 and TNFRSF11A as candidate genes for disease susceptibility.

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  • A possible physiological basis for the discontinuity of consciousness

    Pockett, Susan; Brennan, Barry; Bold, GEJ; Holmes, MD (2011)

    Journal article
    The University of Auckland Library

    A comparison is made between the frequency of local minima in the analytic power of intracranial EEG (ECoG) from waking and unconscious human subjects and the frequency of putative frames of consciousness reported in earlier psychological literature. In ECoG from unconscious subjects, the frequency of deep minima in analytic power is found to be a linear function of bandwidth. In contrast, in ECoG from conscious subjects, the bandwidth/minima-frequency curve saturates or plateaus at minima frequencies similar to the frequencies of previously reported frames of consicousness. This result is consistent with the hypothesis that local minima in analytic power may act as the shutter in a cinematographic model of consciousness. The fact that artificially generated samples of black noise with power spectra similar to ECoG data give similar results in the analyses above suggests that the discontinuous nature of consciousness is not due to some specifically biological factor, but is simply a consequence of the physical properties of the 1/f (aka power law) oscillations that are widely found in nature.

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  • Effect of the amount of excess oxides on the densification of alpha-SiAlON fabricated via a reaction-bonding process

    Kaga, Y; Jones, Mark; Hirao, K; Kanzaki, S (2007)

    Journal article
    The University of Auckland Library

    Y-??-SiAlONs with elongated grains were fabricated via a reaction-bonding process using starting compositions containing excess oxides in the form of Y2O3 and SiO2. The density of post-sintered specimens reached a maximum value with compositions containing 2 mass% excess oxides, although conventionally sintered materials of this composition were not fully dense. However for compositions containing smaller amounts of excess oxides, the density of the specimen fabricated via a reaction-bonding process was lower than that via a conventional process. In these samples it is thought that liquid phase sintering was difficult to be achieve during the post-sintering process, since the amount of SiO2 contained in the starting powder was lower and the Al2O3 in the starting composition was consumed for the production of ??-SiAlON during nitridation. There was also a decrease in density of the reaction-bonded materials with further increases in the amounts of additional oxides. For these samples the compacts could not be densified uniformly, because of non-uniformity of the phase composition in the nitrided compacts. The dense reaction bonded ??-SiAlON with elongated grains, fabricated from compositions with 2 mass% excess oxides exhibited both high fracture toughness and high hardness.

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  • The high reactivity of peroxiredoxin 2 with H2O2 is not reflected in its reaction with other oxidants and thiol reagents

    Peskin, AV; Low, Felicia; Paton, LN; Maghzal, GJ; Hampton, MB; NRCGD, User (2007)

    Journal article
    The University of Auckland Library

    Peroxiredoxin 2 is a member of the mammalian peroxiredoxin family of thiol proteins that is important in antioxidant defense and redox signaling. We have examined its reactivity with various biological oxidants, in order to assess its ability to act as a direct physiological target for these species. Human erythrocyte peroxiredoxin 2 was oxidized stoichiometrically to its disulfide-bonded homodimer by hydrogen peroxide, as monitored electrophoretically under nonreducing conditions. The protein was highly susceptible to oxidation by adventitious peroxide, which could be prevented by treating buffers with low concentrations of catalase. However, this did not protect peroxiredoxin 2 against oxidation by added H2O2. Experiments measuring inhibition of dimerization indicated that at pH 7.4 catalase and peroxiredoxin 2 react with hydrogen peroxide at comparable rates. A rate constant of 1.3 ?? 107 M-1 s-1 for the peroxiredoxin reaction was obtained from competition kinetic studies with horseradish peroxidase. This is 100-fold faster than is generally assumed. It is sufficiently high for peroxiredoxin to be a favored cellular target for hydrogen peroxide, even in competition with catalase or glutathione peroxidase. Reactions of t-butyl and cumene hydroperoxides with peroxiredoxin were also fast, but amino acid chloramines reacted much more slowly. This contrasts with other thiol compounds that react many times faster with chloramines than with hydrogen peroxide. The alkylating agent iodoacetamide also reacted extremely slowly with peroxiredoxin 2. These results demonstrate that peroxiredoxin 2 has a tertiary structure that facilitates reaction of the active site thiol with hydrogen peroxide while restricting its reactivity with other thiol reagents.

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  • Novel pyrazolo[1,5-a]pyridines as PI3K inhibitors: variation of the central linker group

    Kendall, Jackie; Marshall, Andrew; Giddens, Anna; Tsang, KY; Boyd, M; Frederick, R; Lill, CL; Lee, Woo Jeong; Kolekar, Sharada; Chao, M; Malik, A; Yu, S; Chaussade, C; Buchanan, Christina; Rewcastle, Gordon; Baguley, Bruce; Flanagan, JU; Denny, William; Shepherd, PR (2014)

    Journal article
    The University of Auckland Library

    As part of our investigation into the pyrazolo[1,5-a]pyridines as novel PI3K inhibitors, we report a range of analogues where the central linker portion of the molecule was varied while retaining the pyrazolo[1,5-a]pyridine and arylsulfonyl or arylcarbonyl groups. Isostere generating software BROOD was used to assist with producing ideas. The isoform selectivity of the compounds varied from pan-PI3K for compound 41 to p110??-selective for compound 58 or p110??-selective for compound 57. The latter two compounds varied only in their sulphur oxidation state.

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  • Power Law Distributions of Patents as Indicators of Innovation

    O???Neale, Dion RJ; Hendy, Shaun (2012-12-05)

    Journal article
    The University of Auckland Library

    The total number of patents produced by a country (or the number of patents produced per capita) is often used as an indicator for innovation. Here we present evidence that the distribution of patents amongst applicants within many countries is well-described by power laws with exponents that vary between 1.66 (Japan) and 2.37 (Poland). We suggest that this exponent is a useful new metric for studying innovation. Using simulations based on simple preferential attachment-type rules that generate power laws, we find we can explain some of the variation in exponents between countries, with countries that have larger numbers of patents per applicant generally exhibiting smaller exponents in both the simulated and actual data. Similarly we find that the exponents for most countries are inversely correlated with other indicators of innovation, such as research and development intensity or the ubiquity of export baskets. This suggests that in more advanced economies, which tend to have smaller values of the exponent, a greater proportion of the total number of patents are filed by large companies than in less advanced countries.

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  • Audit Fee Stickiness.

    De Villiers, Charl; Hay, David; Zhang, JZ (2014)

    Journal article
    The University of Auckland Library

    Purpose ??? This study aims to contribute to the understanding of audit pricing and the competitiveness of the audit fee market by examining audit fee stickiness. Design/methodology/approach ??? The authors explore the price behavior of audit fees in response to changes in the variables that are usually seen as their determinants, such as size, complexity, and risk in order to examine audit fee stickiness and the competitiveness of the market for audit services. Findings ??? The authors find that audit fees are sticky, i.e. audit fees do not immediately or fully adjust to changes in their determinants. Audit fees also respond to changes leading to an increase more quickly than they respond to changes leading to a decrease. The difference between positive and negative fee adjustments declines over periods longer than one year and is no longer significant when four-year periods are considered. Research limitations/implications ??? The study is limited to companies in the USA from 2000 to 2008. Future research should examine this issue in other settings and periods. Practical implications ??? The results suggest that the audit market is competitive, at least in the medium term. Originality/value ??? The study helps to explain why the audit fee model does not fully explain the level of audit fees; why audit fees are more likely to be too high than too low; and why auditor switches are commonly associated with larger changes in audit fees. The findings provide evidence that may be useful to managers and audit committees when managing their audit fees, auditors when considering the risks and opportunities associated with changes in the determinants of audit fees, and regulators concerned with the competitiveness of the audit market.

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  • Ecospatial outcomes of neoliberal planning: habitat management in Auckland Region, New Zealand

    Coombes, BL (2003)

    Journal article
    The University of Auckland Library

    In line with the paradigmatic shift towards spatial ecology, it is generally accepted that the conservation value of a habitat remnant cannot be determined in isolation from its wider landscape. Sensitivity to the spatial context of forest patches should, therefore, characterise habitat management. Conversely, neoliberal planning disregards ecospatial configuration because it abandons resource decisionmaking to the spatially ad hoc outcomes of market processes. Analysis of bush-lot subdivision -- the foremost protection mechanism for indigenous habitat on private land in the Auckland Region -- demonstrates that the neoliberal agenda for planning contradicts fundamental tenets of conservation ecology. With its foundations in voluntarism and market mechanisms, bush-lot subdivision induces selection bias in the location of protected remnants. Strategic and interventionist approaches will be required to moderate the impact of habitat loss, fragmentation, and perforation.

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  • Lipid and fatty acid composition of likely zooplankton prey of the spiny lobster (Jasus edwardsii) phyllosomas

    Wang, M; Mackenzie, AD; Jeffs, Andrew (2014-05-22)

    Journal article
    The University of Auckland Library

    Several of the world's major spiny lobster fisheries, including Jasus edwardsii in Australasia, have gone into dramatic decline due to decreasing recruitment of their lecithotrophic postlarvae. There is evidence that the decline is related to poor nutritional condition of the postlarvae, especially lipid that is accumulated in large quantities during the preceding pelagic larval stage. Therefore, characterizing the lipid composition of the likely potential zooplankton prey of the larvae (phyllosomas) of spiny lobsters will provide new insights into their nutritional requirements. The lipid class and fatty acid composition of more than 30 species of likely zooplankton prey of the larvae of the spiny lobster, J. edwardsii, were determined. These results showed that most zooplankton prey had a high proportion of their lipid content as polar lipid (PL) (range of 9.4???94.8%, mean of 76.1 ?? 2.6%). Zooplankton prey provide phyllosomas with polyunsaturated fatty acids (PUFA) for growth and development, as well as a range of other important fatty acids that are accumulated as PL and used for fuelling the migration of the subsequent lecithotrophic postlarvae across the continental shelf. Overall, these results indicate that phyllosomas consume prey with wide ranging lipid content, but dominated by PL, and high in docosahexaenoic acid, eicosapentaenoic acid and the key fatty acids used for energy storage.

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  • Macronutrient selection, absorption and energy budget of juveniles of the Australasian sea cucumber, Australostichopus mollis, feeding on mussel biodeposits at different temperatures

    Zamora Allendes, Leonardo; Jeffs, Andrew (2014)

    Journal article
    The University of Auckland Library

    This study was set up to examine the selection and absorption of macronutrients (lipid, protein and carbohydrate) of juveniles of the Australasian sea cucumber Australostichopus mollis, feeding on an effective natural feed (mussel waste) at different temperatures. Our results indicate that the juveniles select and absorb lipid more efficiently than carbohydrate and protein at all temperatures. However, the overall magnitude of absorption of carbohydrate and protein make them the main source of nutritional energy for juvenile sea cucumbers. Seawater temperature affects the feeding behaviour of the juveniles, reducing the selection efficiency of macronutrients, while increasing metabolic energy demand, resulting in less energy available for growth. These results show the importance of each macronutrient in the diet of A. mollis as a source of energy for growth, which opens up the possibility to replace more expensive nutrient sources, such as protein and lipid, with less costly carbohydrate to reduce costs of diet formulation.

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  • Cognition and knowledge sharing in post-acquisition integration: Insights from Indian IT acquiring firms

    Jaura, M; Michailova, Snejina (2014)

    Journal article
    The University of Auckland Library

    Purpose - This paper examines the influence of cognition on knowledge sharing between members of the acquiring and acquired organisation in the post-acquisition integration process. It specifically analyses differentiation between in-groups and out-groups, the perception of organisational identity and interaction among members of the acquired and acquiring organisations and how these three factors affect knowledge sharing. Design/methodology/approach - The authors develop theoretical propositions and conduct an explorative pilot study on the basis of original interview data conducted with ten respondents in four Indian IT companies that have acquired firms abroad. Findings - The authors find evidence for supporting the negative effect of in- and out-group differentiation and the positive effect of inter-personal interaction on knowledge sharing among employees of the acquired and acquiring organisation. There was indicative, but less compelling evidence for the negative influence of inter-group competition and the positive influence of perceived shared organisational identity on knowledge sharing. Different from the established view, the authors find that when Indian firms acquire firms abroad, they initiate immediately knowledge flows from the targets rather than going through a long period of integration prior to acquiring knowledge from the targets. Research limitations/implications - The paper contributes to the scholarly conversation on cognition and knowledge sharing and argues that firms that are located in developing economies and that acquire firms aborad behave in a way someehat different from what the western literature postulates. This invites for further studies, both theporetical and emprical, to shed light on this phenomenon. The present paper is focused only on one country, India, and on a single industry - the IT industry. It is limited in its empirical part, mainly due to enormous difficulties in getting access to the field. Practical implications - The study demonstrates how central individuals are to the process of knowledge sharing and the accomplishment of organisational objectives in a psot-acquisition context. Managers should understand that the knowledge their employees possess is a strategic asset, and therefore how they use it is influential in attaining organisational goals in general and acquisition integration objectives in particular. The creation of task-and project-related communities or groups can help in establishing a shared organisational identity, especially after the turbulent event of one company acquiring another one. The creation of communities or groups where socialisation is encouraged can lead to employees interacting with one another, and developing a sense of belongingness with the community or group. Over time, this belongingness can translate into a shared organisational identity, which is beneficial for the organisation. The findings suggest that the creation of task-or project-oriented communities and groups are a powerful way to achieve that. Originality/value - The contribution of the paper is four-fold. First, while macro orientation dominates the literature on the growth of the Indian IT industry, this study is conducted at individual level of analysis, by focusing on managers in acquiring Indian IT firms. Second, whereas studies that have examined cognition and knowledge sharing have done so mainly through social capital lenses, this paper focuses on factors that are based on the inherent tendency of human beings to categorise themselves and other individuals. Third, the paper examines the links between cognition and knowledge sharing in an exciting context, namely post-acquisition integration. Finally, while research on both post-acquisition integration and on knowledge sharing is biased towards a Western context, this study investigates knowledge sharing and post-acquisition integration in the context of a major non-Western, emerging economy.

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  • Formation of secondary organic aerosol marker compounds from the photooxidation of isoprene and isoprene-derived alkene diols under low-NOx conditions

    Wang, Wu; Iinuma, Yoshiteru; Kahnt, Ariane; Ryabtsova, Oxana; Mutzel, Anke; Vermeylen, Reinhilde; Van der Veken, Pieter; Maenhaut, Willy; Herrmann, Hartmut; Claeys, Magda (2013)

    Journal article
    The University of Auckland Library

    In the present work, we have evaluated whether isomeric C5-alkene diols (1,2-dihydroxy-2-methyl-3-butene, 1,2-dihydroxy-3-methyl-3-butene, and 1,4-dihydroxy-2-methyl-2-butene (cis + trans)), which have first been detected upon photooxidation of isoprene in the absence of NO and are known to be formed in the ambient atmosphere, can serve as precursors for the 2-methyltetrols, C5-alkene triols, and 2-methylglyceric acid under low-NOx conditions. The C5-alkene diols were prepared following published synthesis procedures. It is shown that under the applied chamber conditions the isomeric C5-alkene diols give rise to 2-methyltetrols with different threo/erythro abundance ratios and that certain diols produce 2-methylglyceric acid, but that they do not form C5-alkene triols. Furthermore, it is shown that the photooxidation of isoprene under the applied chamber conditions employing photolysis of H2O2 under dry conditions yields relatively small amounts of C5-alkene triols compared to those of the 2-methyltetrols, unlike under ambient conditions. It is argued that the chamber conditions are not optimal for the formation of C5-epoxydiols, which serve as gas-phase precursors for the C5-alkene triols, and likely as in some previous studies favor the formation of C5-alkene diols as a result of RO2 + RO2 reactions.

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  • Lipids, CHOs, proteins: can all macronutrients put a 'brake' on eating?

    Shin, Hyun Sang; Ingram, JR; McGill, Anne-Thea; Poppitt, Sally (2013-08)

    Journal article
    The University of Auckland Library

    The gastrointestinal (GI) tract and specifically the most distal part of the small intestine, the ileum, has become a renewed focus of interest for mechanisms targeting appetite suppression. The 'ileal brake' is stimulated when energy-containing nutrients are delivered beyond the duodenum and jejunum and into the ileum, and is named for the feedback loop which slows or 'brakes' gastric emptying and duodeno-jejunal motility. More recently it has been hypothesized that the ileal brake also promotes secretion of satiety-enhancing GI peptides and suppresses hunger, placing a 'brake' on food intake. Postprandial delivery of macronutrients to the ileum, other than unavailable carbohydrates (CHO) which bypass absorption in the small intestine en route to fermentation in the large bowel, is an uncommon event and hence this brake mechanism is rarely activated following a meal. However the ability to place a 'brake' on food intake through delivery of protected nutrients to the ileum is both intriguing and challenging. This review summarizes the current clinical and experimental evidence for activation of the ileal brake by the three food macronutrients, with emphasis on eating behavior and satiety as well as GI function. While clinical studies have shown that exposure of the ileum to lipids, CHOs and proteins may activate GI components of the ileal brake, such as decreased gut motility, gastric emptying and secretion of GI peptides, there is less evidence as yet to support a causal relationship between activation of the GI brake by these macronutrients and the suppression of food intake. The predominance of evidence for an ileal brake on eating comes from lipid studies, where direct lipid infusion into the ileum suppresses both hunger and food intake. Outcomes from oral feeding studies are less conclusive with no evidence that 'protected' lipids have been successfully delivered into the ileum in order to trigger the brake. Whether CHO or protein may induce the ileal brake and suppress food intake has to date been little investigated, although both clearly have GI mediated effects. This review provides an overview of the mechanisms and mediators of activation of the ileal brake and assesses whether it may play an important role in appetite suppression.

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  • Anaesthetists' management of oxygen pipeline failure: room for improvement

    Weller, Jennifer; Merry, Alan; Warman, Guy; Robinson, B (2007)

    Journal article
    The University of Auckland Library

    Oxygen pipeline failure is a rare but potentially catastrophic event which can affect the care of patients throughout an entire hospital. Anaesthetists play a critical role in maintaining patient safety, and should be prepared to support an institution-wide emergency response if oxygen failure occurs. We tested the preparedness for this through observation of 20 specialist anaesthetists to a standardised simulator scenario of central oxygen supply failure. Responses were documented using multiple approaches to ensure accuracy. All anaesthetists demonstrated safe immediate patient care, but we observed a number of deviations from optimal management, including failure to conserve oxygen supplies and, following restoration of gas supplies, failure to test the composition of the gas supplied from the repaired pipelines. This has implications for patient care at both individual and hospital level. Our results indicate a gap in anaesthesia training which should be addressed, in conjunction with planning for effective hospital-wide responses to the event of critical resource failure.

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