Non-specific conducting polymer-based array capable of monitoring odour emissions from a biofiltration system in a piggery building

A commercial non-specific gas sensor array system was evaluated in terms of its capability to monitor the odour abatement performance of a biofiltration system developed for treating emissions from a commercial piggery building. The biofiltration system was a modular system comprising an inlet ducting system, humidifier and closed-bed biofilter. It also included a gravimetric moisture monitoring and water application system for precise control of moisture content of an organic woodchip medium. Principal component analysis (PCA) of the sensor array measurements indicated that the biofilter outlet air was significantly different to both inlet air of the system and post-humidifier air. Data pre-processing techniques including normalising and outlier handling were applied to improve the odour discrimination performance of the non-specific gas sensor array. To develop an odour quantification model using the sensor array responses of the non-specific sensor array, PCA regression, artificial neural network (ANN) and partial least squares (PLS) modelling techniques were applied. The correlation coefficient (r(2)) values of the PCA, ANN, and PLS models were 0.44, 0.62 and 0.79, respectively.

Mitochondrial DNA supports the identification of two endangered river sharks (Glyphis glyphis and Glyphis garricki) across northern Australia

The river sharks (genus Glyphis) are a small group of poorly known sharks occurring in tropical rivers and estuarine waters across northern Australia, south-east Asia and the subcontinent. The taxonomy of the genus has long been unclear due to very few individuals having been caught and examined, resulting in a paucity of data regarding their distribution, biology and ecology. Only recently has attention focussed on the two Australian species, G. glyphis and G. garricki. This study is a result of a rare opportunity to collate the few samples that have been collected from these species and the bull shark Carcharhinus leucas, which shares an overlapping range. These samples were analysed using the DNA barcoding approach (cox1 mitochondrial gene), compared with six other species of carcharhinids and evaluated in light of the current taxonomic classification. Nine species-specific nucleotide differences were found between G. glyphis and G. garricki and no intra-specific variation provides strong support for the separation into distinct species. Significant differences were also observed at the inter-generic level, with Glyphis forming a distinct clade from Carcharhinus. This study provides the basis for future molecular studies required to better address conservation issues confronting G. glyphis and G. garricki in Australia.

Recrudescent Infection Supports Hendra Virus Persistence in Australian Flying-Fox Populations

Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of recrudescence merits increased attention.