Assessment of the sensitivity of current standard procedures for the isolation of Yersinia enterocolitica from pork mince : a dissertation presented in partial fulfilment (25%) of the requirements for the degree of Master of Veterinary Studies in Veterinary Public Health at Massey University

Y. enterocolitica and related species have been isolated from many types of food. The majority of isolates differ in biochemical and serological characteristics from typical pathogenic strains and are termed non-pathogenic or environmental strains. Usually the number of Y. enterocolitica organisms present in food products is low compared with the dominant background flora. The ability of current enrichment procedures to recover pathogenic strains of Y. enterocolitica from different foods is often inadequate probably because different strains require different conditions for optimum growth (De Boer 1992). An efficient enrichment procedure should confer some selective advantage to the desired type of microorganism by promoting its growth relative to the competing microflora. At present, there is no single ideal isolation procedure available for the recovery of pathogenic strains of Y. enterocolitica from foods. The aim of this study was to determine the recovery rate of Y. enterocolitica biotype 4/serotype 0:3 from samples of pork mince inoculated with known numbers of the microorganism using different enrichment parameters (Time, temperature and pH) and Cefsulodin-Irgasan-Novobiocin (CIN) agar as the selective medium. The experiment was conducted in two trials using different bacterial dilutions. Three pork mince samples in duplicate were inoculated with known quantities of Y. enterocolitica biotype 4/serotype 0:3 organisms and subjected to cold enrichment in phosphate buffered saline (PBS) with a pH of 7.6, 6.6 and 5.5 at 25°C for 2 days, 10°C for 7 days and 4°C for 21 days. CIN agar was used as the selective medium. Pre-inoculation control samples were selected and plated in CIN on day O and on day 21 after PBS enrichment at 4°C. In Trial one Y. enterocolitica organisms were recovered from all 3 samples incubated at 25°C for 2 days and from 1 out of 3 inoculated samples incubated at 4°C for 21 days. There were no organisms recovered from other inoculated samples. The control sample did not show any environmental contamination with Yersinia species. In Trial two, Y. enterocolitica was recovered from 1 out of 3 duplicate samples enriched in PBS with pH 6.6 and incubated at 25°C for two days. Y. enterocolitica was not recovered from other inoculated samples. Y. intermedia was isolated from all pH, temperature and time combinations and also from control samples. The following conclusions can be drawn from this experiment. Incubation at high temperature (25°C) and short duration (48 hours) can be used as an efficient method for isolating Y. enterocolitica from pork samples. The standard incubation period of 21 days required for cold enrichment at 4°C is too long for the isolation of pathogenic strains, because of possible growth of environmental microorganisms. A pH of 6.6 is less efficient than 7.6 for enrichment although occasional isolation can be made using this pH. Enrichment in PBS with a pH of 5.5 with any time as well as temperature combinations and incubation at 10°C for 7 days are not ideal for isolation of pathogenic Yersinia enterocolitica strains. Of the three enrichments (PBS 7.6, 6.6, 5.5) used in this experiment, PBS with pH 7.6 was found to be most efficient to others

Sensor-AssistedWeighted Average Ensemble Model for Detecting Major Depressive Disorder

The present methods of diagnosing depression are entirely dependent on self-report ratings or clinical interviews. Those traditional methods are subjective, where the individual may or may not be answering genuinely to questions. In this paper, the data has been collected using self-report ratings and also using electronic smartwatches. This study aims to develop a weighted average ensemble machine learning model to predict major depressive disorder (MDD) with superior accuracy. The data has been pre-processed and the essential features have been selected using a correlation-based feature selection method. With the selected features, machine learning approaches such as Logistic Regression, Random Forest, and the proposedWeighted Average Ensemble Model are applied. Further, for assessing the performance of the proposed model, the Area under the Receiver Optimization Characteristic Curves has been used. The results demonstrate that the proposed Weighted Average Ensemble model performs with better accuracy than the Logistic Regression and the Random Forest approaches

A numerically efficient technique for the analysis of slots in multilayer media

Cataloged from PDF version of article.A numerically efficient technique for the analysis of slot geometries in multilayer media is presented using closed-form Green's functions in spatial domain in conjunction with the method of moments (MoM). The slot is represented by an equivalent magnetic-current distribution, which is then used to determine the total power crossing through the slot and the input impedance. In order to calculate power and current distribution, spatial domain closed form Green's functions are expanded as power series of the radial distance rho, which makes the analytical evaluation of the spatial domain integrals possible, saving a considerable amount of computation time

Nutritional potential of bamboo leaves for feeding dairy cattle

Feed shortage during the dry season in the highlands of Madagascar negatively impacts the dairy cattle productivity, as well as the farmers' income. Bamboo can produce a high quantity of biomass and could be an alternative way to increase the fodder supply for cattle. The present study aimed to assess the compositional information and the optimal rate of bamboo as fodder for dairy cattle. Leaf samples from nine bamboo species were collected to determine their chemical composition and nutritive value. A feeding experiment was also conducted using ten dairy cows, over ten weeks. Bamboo leaves were mixed with maize silage in five proportions: SIL0:BAM100, SIL25:BAM75, SIL50:BAM50, SIL75:BAM25 and SIL100:BAM0. The contents of dry matter, total ash and crude protein in the bamboo leaves were, respectively, 44.5-64.6 %, 6.68-18.5 % and 7.71-15.4 %. In the feeding trial, the dry matter intake of bamboo leaves was 1.6-7.1 kg per day, with an average of 4.8 kg per day. The dry matter apparent digestibility of bamboo leaves was 37.4-56.4 %. The milk production reached 13.6-14.4 L per cow, per day, but there was no significant difference concerning the rate of bamboo leaves in the mixed diet (p > 0.05). The introduction of bamboo leaves into the ruminants diet did not affect their milk production

Recycled glass fibre/polyester composites : processing and mechanical characterization

The present article demonstrates the recycling and reuse of waste glass fibre fabrics. The recycled regenerated long glass fibres are impregnated with polyester resin to study the mechanical performance under tensile loading conditions. The specimens are prepared from the laminates made by using vacuum assisted resin infusion technique. Therefore high quality specimens are chosen for this study. Several processing issues were identified and also evaluated the quality of specimen before the test and evaluated fracture surfaces of the tested sample to predict the failure modes. The research study includes the development of silane treatments for the recycled glass fibres to regenerate the glass fibre surface. Experiments are conducted for the reference laminate (CSM as received), Heat Treated glass fibres without any sizings on surface, and silane treated glass fibres with heat treatment. Scanned electron microscopy demonstrated the differences in the fibre surface patterns. The results demonstrate the comparison of tensile performances both at single fibre and composite levels