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Trip E.D.L.,University of Auckland | Trip E.D.L.,Nelson Marlborough Institute of Technology | Trip E.D.L.,Auckland University of Technology | Clements K.D.,University of Auckland | And 2 more authors.
Marine Biology | Year: 2016

Increased temperatures are associated with reduced body sizes, life spans, and reproductive outputs in shallow water marine fishes, reflecting the pervasive effects of temperature on metabolic rates in ectotherms. Herbivorous fishes have been seen as an exception to this trend, based on the hypothesis that physiological and demographic processes in these species are constrained by the inability to digest algae at low temperatures. It is thus argued that increased temperatures deliver a net benefit to herbivorous fishes. This study examines an alternative argument, that warming temperatures can have increasingly inimical effects on temperate piscine herbivores. We consider the hypothesis that herbivores experience greater oxidative stress at warmer temperatures, a consequence of temperature-related increases in metabolic rates. We use the age pigment lipofuscin to examine the rate of oxidative damage accumulation in populations of a temperate marine herbivorous fish, Odax pullus (Labridae), at different latitudes (temperatures) across New Zealand (175.3°E, 36.3°S–167.9°E, 47°S). We show a 55 % faster rate of oxidative damage accumulation in shorter-lived fish living at warmer latitudes. In these populations, it took 33–50 % fewer years to accumulate similar amounts of oxidative damage than in those living at colder latitudes, indicating greater oxidative stress in fish living at warmer temperatures. We conclude that at least some temperate piscine herbivores will be exposed to negative demographic impacts at their low-latitude range margins as temperatures increase. © 2016, Springer-Verlag Berlin Heidelberg.

Mohammad R.M.,University of Huddersfield | Thabtah F.,Nelson Marlborough Institute of Technology | McCluskey L.,University of Huddersfield
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

Creating a neural network based classification model is traditionally accomplished using the trial and error technique. However, the trial and error structuring method nornally suffers from several difficulties including overtraining. In this article, a new algorithm that simplifies structuring neural network classification models has been proposed. It aims at creating a large structure to derive classifiers from the training dataset that have generally good predictive accuracy performance on domain applications. The proposed algorithm tunes crucial NN model thresholds during the training phase in order to cope with dynamic behavior of the learning process. This indeed may reduce the chance of overfitting the training dataset or early convergence of the model. Several experiments using our algorithm as well as other classification algorithms, have been conducted against a number of datasets from University of California Irvine (UCI) repository. The experiments’ are performed to assess the pros and cons of our proposed NN method. The derived results show that our algorithm outperformed the compared classification algorithms with respect to several performance measures. © Springer International Publishing Switzerland 2016.

Livingston M.,University of Otago | Fidler A.,Cawthron Institute | Fidler A.,University of Auckland | Mellor D.,Nelson Marlborough Institute of Technology | And 4 more authors.
Avian Pathology | Year: 2013

An enzyme-linked immunosorbent assay (ELISA) was developed to estimate levels of IgY antibody against the bacterium Erysipelothrix rhusiopathiae in serum samples collected from the critically endangered kakapo (Strigops habroptilus, Psittaciformes, Aves) before and after vaccination against this bacterium. Relative IgY antibody titres in pre-vaccination serum samples (n = 71 individual kakapo) were normally distributed with the exception of four outliers which displayed low IgY levels. Notably all four low IgY samples were collected from fledglings 3 - 6 months old. Pre-vaccination serum samples from nine nestlings <3 months old, seven of which were hatched in incubators and had no contact with either adult kakapo or their natural environment (e.g. soil), were found to have relatively high IgY levels, suggesting transfer of maternal IgY molecules to fledglings via the yolk. IgY levels in pre-vaccination serum samples from seven kakapo aged 25 - 30 months were also relatively high, suggesting that most kakapo naturally acquire anti- E.rhusiopathiae IgYs within their first 2 years. There was no evidence that vaccination increased the kakapo population's mean anti-E.rhusiopathiae IgY levels. However, there was a significant negative relationship between an individual bird's pre-vaccination IgY level and any subsequent increase following vaccination, suggesting that vaccination may only raise the IgY levels of birds with relatively low pre-vaccination IgY levels. A statistical model of the relationship between 'death from erysipelas' and sex, age and transfer from one to island sanctuary to another found that only transfer was significantly associated with death from erysipelas. © 2013 Houghton Trust Ltd.

Kjellstrom T.,Umea University | Kjellstrom T.,Australian National University | Kjellstrom T.,University College London | Lemke B.,Nelson Marlborough Institute of Technology | Otto M.,Nelson Marlborough Institute of Technology
Industrial Health | Year: 2013

A feature of climate impacts on occupational health and safety are physiological limits to carrying out physical work at high heat exposure. Heat stress reduces a workers work capacity, leading to lower hourly labour productivity and economic output. We used existing weather station data and climate modeling grid cell data to describe heat conditions (calculated as Wet Bulb Globe Temperature, WBGT) in South-East Asia. During the hottest month in this region (March) afternoon WBGT levels are already high enough to cause major loss of hourly work capacity and by 2050 the situation will be extreme for many outdoor jobs. © 2013 National Institute of Occupational Safety and Health.

Kjellstrom T.,Health and Environment International Trust | Kjellstrom T.,University of Kuala Lumpur | Lemke B.,Nelson Marlborough Institute of Technology | Hyatt O.,Health and Environment International Trust | Otto M.,Nelson Marlborough Institute of Technology
South African Medical Journal | Year: 2014

A number of aspects of human health are caused by, or associated with, local climate conditions, such as heat and cold, rainfall, wind and cloudiness. Any of these aspects of health can also be affected by climate change, and the predicted higher temperatures, changes in rainfall, and more frequent extreme weather conditions will create increased health risks in many workplaces. Important occupational health risks include heat stress effects, injuries due to extreme weather, increased chemical exposures, vector-borne diseases and under-nutrition. In South Africa (SA), and many other parts of the world experiencing a hot season each year, the effects of heat stress may be of greatest relevance to the large working populations in mining, agriculture, construction, quarries and outdoor services. Factory and workshop heat will also become an increasing problem in the numerous workplaces without effective cooling systems. SA was the location for some of the most detailed research on heat effects at work in mines in the 1950s and 1960s, and the future will bring new challenges not only for mines, but also for many other workplaces. The climate model trends for this century indicate that the heat exposure may increase by 2 - 4°C during the hottest months, and this would change the occupational heat situation from 'low risk' to 'moderate or high risk' in much of SA.

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