262 research outputs found

    Time series analyses of inflation in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Statistics at Massey University

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    Modelling of the economy has become increasingly important over the years. It serves two main purposes. It enables forecasts and it can be used for the evaluation of various economic policies. Economic models come with various degrees of size and statistical complexity. Models can be of a qualitative or of a quantitative nature. The soundness of the statistical techniques that are used for quantitative models is critical. In recent years a number of such techniques have been developed. This thesis will evaluate some on existing economic New Zealand time series. Inflation plays a main role in everyday life and it has been of major ongoing concern to the New Zealand governments in recent times. These governments have instructed the Reserve Bank of New Zealand (RBNZ) to set monetary policies to ensure certain targets are met. The RBNZ achieves this to a large degree by setting the Official Cash Rate which is the major determinant of the interest rates that are used by the banks. This thesis will consider some theoretical aspects of time series analysis. In particular the Dickey-Fuller tests and cointegration analysis are considered. Also some theoretical aspects of inflation are considered. Examples are given of aspects of New Zealand life other than the interest rates that may also affect the current inflation rates. The time series that were analysed could be categorised as inflation indices, monetary aggregates, interest rates and gross domestic product. The thesis attempted to evaluate the time series in such a manner that there was little room for an analyst's bias. This was mainly achieved by developing a standardised approach to the analysis of these series. A number of interactions between the time series were evaluated and some were identified as being suitable for further research with the ultimate aim of developing a small model of the New Zealand economy. Another aim was to evaluate some aspects of economic policy where possible given the small number of time series that were used. Granger Causality tests seemed to show the effect of economic policy, where the interest rates affect the inflation rates. However, this was not further supported by cointegration analyses. There are various possible explanations for this. It was surmised that the standardised way of analysis may not have identified this relationship where it existed. The analyses showed that at times the results of the statistical tests were inconsistent. This applied to the Dickey-Fuller tests as well as the cointegration analyses. In some cases unit root models with significant coefficients for the deterministic components were identified. Further analysis would show that the deterministic components were not significant after all. However, the resulting models without these components did not have a unit root. The cointegration analyses invariably showed a number of Vector Error Correction Models with significant cointegration equations. Since their economic implications would be quite different at times there was a reason for concern. In conclusion there are some worrying problems when the methodology is used for existing short New Zealand data series. However, at times some plausible results were shown as well. Suggestions for further research were made

    Model applications of decision support systems in meat hygiene programs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University

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    Current systems to ensure safety of meat are to a large degree based on a "procedural" approach which specifies what inspection actions will be taken to protect human health. Both knowledge and disease priorities have changed substantially over recent decades, and moreover the scale of the problems created by any breakdowns in protection has escalated greatly, as food trading and consumption patterns have changed. It is now recognized that meat hygiene needs to focus primarily on ways by which the risk that product will represent a hazard to human health can be effectively reduced, rather than merely ensuring compliance with a defined set of procedures. In addition to human food safety, meat inspection has the potential to contribute information to improve animal health on a national and a local scale. This thesis examines example issues in order to identify possible approaches to the development of decision support systems which assist in protecting meat consumers and improving the health of livestock on farms. The main areas which were explored for this purpose were respiratory disease in lambs and chemical residues in slaughter animals. A literature review of pneumonia and pleurisy in lambs showed that numerous factors have been proposed as predisposing causes for these diseases, but there was surprisingly little valid experimental or observational research evidence to support such statements. A hazard analysis was performed for the micro-organisms which have been isolated from pneumonic lungs. The major commonly detected organisms did not appear to cause a risk to healthy people. However there were a number of micro-organisms which are isolated on occasion from pneumonic and sometimes from healthy sheep lungs that might cause human disease. A case-control study was carried out as an exploratory means to identify risk factors and to generate hypotheses about causal processes. A number of risk factors were initially identified at univariate level. At the second stage the importance of some of these risk factors was quantified in a logistic regression model. Finally a third stage analysis showed the interactions between the factors in a logistic path model, which consisted of three clusters. One cluster included characteristics of the farm and paddocks, one cluster included the yards and practices in the yards, and a third cluster included the types and number of animals on the farm. Two intervention studies were subsequently carried out to evaluate the effect of making various management modifications on the prevalence of pneumonia and pleurisy at slaughter. One intervention study evaluated the time lambs spent in the yards after weaning and the use or oral or injectable drenches. The second intervention study evaluated the use of oral versus injectable drenches and the use of a shower dip versus a wand. The intervention studies showed an effect of time in the yards on pneumonia. There was some association between time in the yards and acute localised pleurisy but none between the other measures tested and respiratory disease. The studies showed clear temporal patterns with regard to pleurisy and pneumonia and enabled comparisons to be made between farms. A study of inspection for pleurisy at slaughterhouses was analysed. The analysis identified the temporal patterns of certain types of pleurisy. Comparisons were made between four participating premises. The sensitivity and specificity of meat inspection for the various types of pleurisy was analysed. The pleurisy data over an eleven year period of the entire country were analysed. Differences were shown between islands and regions. The potential for development of components of a decision support system for pneumonia and pleurisy was illustrated with a number of examples. An important component was to determine how farmers could be assisted in improving the health of their lambs with regard to pleurisy. Ideas to improve farmer involvement were developed. The principles of a decision support system which evaluated the issue of cross-contamination due to handling of product by the inspector were developed. Epidemiological principles of chemical residues in slaughter animals were investigated. A number of statistical quality control tests were applied to known data sets to evaluate what sample sizes would be required to detect changing trends or spatial paterns. Temporal simulations were performed to determine how well clusters in time could be detected. The Moving Average approach was used and it appeared that with the given data set sample sizes well beyond those feasible to achieve would be required. Spatial analyses with a number of different statistics were performed. In this case also, large sample sizes were required for reliable results. It was concluded that use of a risk analysis model to define a risk-reduction strategy targeted to avoid any significant risk to the consumer offered a much more effective tool than a fixed sampling system. This model combines a range of possible risk reduction measures in various mixes, and determines whether or not each of the tested strategies achieves the goal of making it very improbable that a consumer would be exposed to sufficient levels of chemical residues in food to even constitute some minimal public health risk

    DEVELOPMENT OF VIRTUAL EVENT MARKETING

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    In the last few years the Pichia pastoris expression system has been gaining more and more interest for the expression of recombinant proteins. Many groups have employed fermentation technology in their investigations because the system is fairly easy to scale up and suitable for the production in the milligram to gram range. A large number of heterologous proteins from different sources has been expressed, but the fermentation process technology has been investigated to a lesser extent. A large number of fermentations are carried out in standard bioreactors that may be insufficiently equipped to meet the demands of high-cell-density fermentations of methylotrophic yeasts. In particular, the lack of on-line methanol analysis leads to fermentation protocols that may impair the optimal expression of the desired products. We have used a commercially available methanol sensor to investigate in detail the effects of supplementary glycerol feeding while maintaining a constant methanol concentration during the induction of a Mut+ strain of Pichia pastoris. Specific glycerol feed rates in the range of 38-4.2 mg × g(exp -1) × h(exp -1) (mg glycerol per gram fresh weight per hour) were investigated. Expression of the recombinant scFv antibody fragment was only observed at specific feed rates below 6 mg × g(exp -1) × h(exp -1). At low specific feed rates, growth was even lower than with methanol as the sole carbon source and the harvest expression level of the scFv was only half of that found in the control fermentation. These results show that glycerol inhibits expression driven by the AOX1 promoter even at extremely limited availability and demonstrate the benefits of on-line methanol control in Pichia fermentation research

    Virally induced modulation of murine IgG antibody subclasses.

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    The isotypic distribution of murine IgG was examined after infection with several viruses. The results indicate that when a hypergammaglobulinemia was induced by the infection, it was restricted to the IgG2a and, to a lesser extent, to the IgG2b subclasses. In addition, when mice were infected with some viruses concomitantly with the immunization with a soluble protein antigen, a modification in the isotypic distribution of antiprotein antibodies was observed, with a preferential production of IgG2a. These observations indicate that viral infections can actively influence the switch of Igs and selectively stimulate the production of the IgG2a subclass

    Albumin determined by bromocresol green leads to erroneous results in routine evaluation of patients with chronic kidney disease

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    Objectives: Measurement of plasma albumin is pivotal for clinical decision-making in patients with chronic kidney disease (CKD). Routinely used methods as bromocresol green (BCG) and bromocresol purple (BCP) can suffer from aselectivity, but the impact of aselectivity on the accuracy of plasma albumin results of CKD-patients is still unknown. Therefore, we evaluated the performance of BCG-, BCP- and JCTLM-endorsed immunological methods in patients with various stages of CKD. Methods:We evaluated the performance of commonly used albumin methods in patients with CKD stages G1 through G5, the latter divided in two groups based on whether they received hemodialysis treatment. In total, 163 patient plasma samples were measured at 14 laboratories, on six different BCG and BCP-platforms, and four different immunological platforms. The results were compared with an ERM-DA-470k-corrected nephelometric assay. The implications on outcome is evaluated by the proportion of patient results &lt;38g/L for the diagnosis of protein energy wasting. Results:Albumin results determined with BCP- and immunological methods showed the best agreement with the target value (92.7 and 86.2%, respectively vs. 66.7% for BCG, namely due to overestimation). The relative agreement of each method with the target value was platform-dependent, with larger variability in agreement between platforms noted for BCG and immunological methods (3.2-4.6 and 2.6-5.3%) as opposed to BCP (0.7-1.5%). The stage of CKD had similar effects on the variability in agreement for the three method-groups (0.6-1.8% vs. 0.7-1.5% vs. 0.4-1.6%). The differences between methods cause discrepancies in clinical decision-making, as structurally fewer patients were diagnosed with protein energy wasting upon using BCG-based albumin results. Conclusions: Our study shows that BCP is fit for the intended use to measure plasma albumin levels in CKD patients from all stages, including patients on hemodialysis. In contrast, most BCG-based platforms falsely overestimate the plasma albumin concentration.</p
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