title: Subcubic trades in Steiner triple systems

authors: Cavenagh, Nicholas J.

subjects: Science & Technology

abstract: We consider the problem of classifying trades in Steiner triple systems such that each block of the trade contains one of three fixed elements. We show that the fundamental building blocks for such trades are 3-regular graphs that are 1-factorisable. In the process we also generate all possible 2- and 3-way simultaneous edge colourings of graphs with maximum degree 3 using at most 3 colours, where multiple edges but not loops are allowed. Moreover, we generate all possible Latin trades within three rows.

text: Subcubic trades in Steiner triple systems We consider the problem of classifying trades in Steiner triple systems such that each block of the trade contains one of three fixed elements. We show that the fundamental building blocks for such trades are 3-regular graphs that are 1-factorisable. In the process we also generate all possible 2- and 3-way simultaneous edge colourings of graphs with maximum degree 3 using at most 3 colours, where multiple edges but not loops are allowed. Moreover, we generate all possible Latin trades within three rows.

year: 2017

title: Deterring birds from baits by manipulating colour and odour

authors: Hartley, Lynette J.

abstract: Poisonous baits are used extensively in New Zealand to control introduced mammalian pest species particularly brushtail possums (Trichosurus vulpecula) and rats (Rattus rattus, R. norvegicus, R. exulans). This thesis examined bait characteristics that could be manipulated to make poisonous baits less attractive to native birds. The first characteristic examined was colour as the appearance of foods was believed to be important to foraging birds. The target mammalian species may be more attentive when foraging to other aspects of food such as taste and smell. A six colour choice method for testing colour preference in birds was developed using chickens (Gallus domesticus). The procedure involved testing birds individually, on six occasions, with novel food of six different colours presented simultaneously. All three species of birds tested; captive New Zealand weka (Gallirallus australis), wild New Zealand robins (Petroica australis), and free range domestic chickens showed similar colour preferences. The red and yellow novel food was preferred to the blue novel food. Baits in New Zealand are currently dyed green to deter birds but this study suggested blue may be a more effective deterrent.

There was considerable individual variability in colour preference suggesting one colour is not likely to deter all birds in a population from poisonous baits. Both weka and chickens showed a pattern of increasing consumption from test to test and the implications of this behaviour pattern are discussed in terms of poisonous bait consumption.

Free range chickens were used to investigate whether chickens avoided some shades of blue more than others but no preferences were detected. The relative luminance of the colours offered to the chickens was calculated, however, and there was an indication that chickens preferred lighter rather than darker colours. I would suggest, therefore, that light coloured poisonous baits should not be used.

It was suggested that natural predator-prey systems may provide useful concepts for the design of bird deterrents. Many toxic insects have a combination of several conspicuous characteristics, all of which assault different senses at the same time. I investigated combinations of colour, novelty and methyl pyrazine, an odour used by toxic insects to deter birds. Wild robins were not deterred from familiar food by methyl pyrazine odour and the addition of methyl pyrazine did not alter chickens’ colour preferences or their consumption of novel food. Pyrazine, however, was very effective in deterring captive weka from red and blue novel food. The weka ate very little of either colour when it was associated with pyrazine odour.

The combination of pyrazine and blue, which was effective in captivity, was tested in the field using real (non toxic) baits. Consumption over six days was compared with that of the green-coloured, cinnamon-flavoured, baits commonly used in poisoning operations. Fewer of the blue-pyrazine baits were eaten on the first day and there was an indication that consumption of blue-pyrazine baits was lower overall. Methyl pyrazine may be useful in deterring birds from poisonous baits and is certainly worthy of more investigation.

text: Deterring birds from baits by manipulating colour and odour Poisonous baits are used extensively in New Zealand to control introduced mammalian pest species particularly brushtail possums (Trichosurus vulpecula) and rats (Rattus rattus, R. norvegicus, R. exulans). This thesis examined bait characteristics that could be manipulated to make poisonous baits less attractive to native birds. The first characteristic examined was colour as the appearance of foods was believed to be important to foraging birds. The target mammalian species may be more attentive when foraging to other aspects of food such as taste and smell. A six colour choice method for testing colour preference in birds was developed using chickens (Gallus domesticus). The procedure involved testing birds individually, on six occasions, with novel food of six different colours presented simultaneously. All three species of birds tested; captive New Zealand weka (Gallirallus australis), wild New Zealand robins (Petroica australis), and free range domestic chickens showed similar colour preferences. The red and yellow novel food was preferred to the blue novel food. Baits in New Zealand are currently dyed green to deter birds but this study suggested blue may be a more effective deterrent.

There was considerable individual variability in colour preference suggesting one colour is not likely to deter all birds in a population from poisonous baits. Both weka and chickens showed a pattern of increasing consumption from test to test and the implications of this behaviour pattern are discussed in terms of poisonous bait consumption.

Free range chickens were used to investigate whether chickens avoided some shades of blue more than others but no preferences were detected. The relative luminance of the colours offered to the chickens was calculated, however, and there was an indication that chickens preferred lighter rather than darker colours. I would suggest, therefore, that light coloured poisonous baits should not be used.

It was suggested that natural predator-prey systems may provide useful concepts for the design of bird deterrents. Many toxic insects have a combination of several conspicuous characteristics, all of which assault different senses at the same time. I investigated combinations of colour, novelty and methyl pyrazine, an odour used by toxic insects to deter birds. Wild robins were not deterred from familiar food by methyl pyrazine odour and the addition of methyl pyrazine did not alter chickens’ colour preferences or their consumption of novel food. Pyrazine, however, was very effective in deterring captive weka from red and blue novel food. The weka ate very little of either colour when it was associated with pyrazine odour.

The combination of pyrazine and blue, which was effective in captivity, was tested in the field using real (non toxic) baits. Consumption over six days was compared with that of the green-coloured, cinnamon-flavoured, baits commonly used in poisoning operations. Fewer of the blue-pyrazine baits were eaten on the first day and there was an indication that consumption of blue-pyrazine baits was lower overall. Methyl pyrazine may be useful in deterring birds from poisonous baits and is certainly worthy of more investigation.

year: 1999

title: The “standard story” of anti-Māori talk in Pae Ora (Healthy Futures) Bill submissions

authors: Black, Rose

abstract: AIM: To review some common patterns of race talk in a sample of submissions made to the Pae Ora (Healthy Futures) Bill. This bill proposed a structural reform of the health system in Aotearoa New Zealand to address long-standing health inequities experienced by Māori, the Indigenous peoples, and other priority populations. METHOD: In a sample of 3,000 individual submissions made in late 2021, we found 2,536 explicit references to race. Utilising the “stan-dard story” frame of Pākehā/non-Maori race talk, five longer submissions that inferred that the Pae Ora bill was “racist” were analysed in detail. RESULTS: Many “standard story” race discourses were identified in the Pae Ora submissions. Three derived discourses included in this paper are: Pākehā as norm (monoculturalism or not seeing Pākehā as a culture), equality and the “Treaty” (equality for all to access healthcare), and one people (we are all New Zealanders). Sources such as the Waitangi Tribunal Wai 2575 Hauora report were drawn on to provide alternative discourses. CONCLUSION: Identifying Pākehā standard story discourses enables learning about language patterns systems draw on, and the development of tools and procedures to improve equity for Māori and eliminate institutional racism.

text: The “standard story” of anti-Māori talk in Pae Ora (Healthy Futures) Bill submissions AIM: To review some common patterns of race talk in a sample of submissions made to the Pae Ora (Healthy Futures) Bill. This bill proposed a structural reform of the health system in Aotearoa New Zealand to address long-standing health inequities experienced by Māori, the Indigenous peoples, and other priority populations. METHOD: In a sample of 3,000 individual submissions made in late 2021, we found 2,536 explicit references to race. Utilising the “stan-dard story” frame of Pākehā/non-Maori race talk, five longer submissions that inferred that the Pae Ora bill was “racist” were analysed in detail. RESULTS: Many “standard story” race discourses were identified in the Pae Ora submissions. Three derived discourses included in this paper are: Pākehā as norm (monoculturalism or not seeing Pākehā as a culture), equality and the “Treaty” (equality for all to access healthcare), and one people (we are all New Zealanders). Sources such as the Waitangi Tribunal Wai 2575 Hauora report were drawn on to provide alternative discourses. CONCLUSION: Identifying Pākehā standard story discourses enables learning about language patterns systems draw on, and the development of tools and procedures to improve equity for Māori and eliminate institutional racism.

year: 2023-07-21