title: Behaviour Determinants of the 'Choose-Short Effect'

authors: Hoogstraten, Sarah Michelle

subjects: Hens

abstract: This study aimed to elucidate the mechanisms behind the behavioural phenomenon called the 'choose-short effect' by exploring the hen’s ability to discriminate temporal stimuli in delayed match-to-sample  DMTS) procedure. This experiment aimed to add to the understanding of the behavioural processes that affect animals’ ability to perceive time and how an animal’s own actions can influence their perception of time. The Behaviour Theory of Timing (BeT; Killeen & Fetterman, 1988) assumes that the hens own behaviour mediates their ability to time. This assumption was tested in the present experiment by introducing a ‘response-requirement’ during the sample stimulus on a two alternative forced choice temporal discrimination.  If the assumptions of BeT are correct the response requirement should increase accuracy with temporal discriminations as it can serve as discriminative stimulus signalling in the passage of time. Each hen experienced two experimental phases called ‘No-response required’ (NR) and ‘Response required’ (RR) in a DMTS procedure. In the ‘NR’ conditions the house light was illuminated for either 3 s or 9 s serving as the ‘sample’ stimuli. After the sample stimulus was presented the ‘back-key’ was illuminated and the first response to the back-key activated the choice keys after a randomly selected delay of either 0 s, 3 s, 9 s or 12 s. For the ‘RR’ condition the procedure was the same as the ‘No-light’ condition apart from the ‘back key’ was illuminated throughout the sample presentation.  Results showed that there was no particular group bias towards reporting stimuli as ‘short’. However, the hens had higher accuracy in the ‘RR’ conditions when the ‘back key’ was illuminated throughout sample presentation then when it was not (‘NR’ conditions). This suggests that the animals own behaviour improved their ability to time.

text: Behaviour Determinants of the 'Choose-Short Effect' This study aimed to elucidate the mechanisms behind the behavioural phenomenon called the 'choose-short effect' by exploring the hen’s ability to discriminate temporal stimuli in delayed match-to-sample  DMTS) procedure. This experiment aimed to add to the understanding of the behavioural processes that affect animals’ ability to perceive time and how an animal’s own actions can influence their perception of time. The Behaviour Theory of Timing (BeT; Killeen & Fetterman, 1988) assumes that the hens own behaviour mediates their ability to time. This assumption was tested in the present experiment by introducing a ‘response-requirement’ during the sample stimulus on a two alternative forced choice temporal discrimination.  If the assumptions of BeT are correct the response requirement should increase accuracy with temporal discriminations as it can serve as discriminative stimulus signalling in the passage of time. Each hen experienced two experimental phases called ‘No-response required’ (NR) and ‘Response required’ (RR) in a DMTS procedure. In the ‘NR’ conditions the house light was illuminated for either 3 s or 9 s serving as the ‘sample’ stimuli. After the sample stimulus was presented the ‘back-key’ was illuminated and the first response to the back-key activated the choice keys after a randomly selected delay of either 0 s, 3 s, 9 s or 12 s. For the ‘RR’ condition the procedure was the same as the ‘No-light’ condition apart from the ‘back key’ was illuminated throughout the sample presentation.  Results showed that there was no particular group bias towards reporting stimuli as ‘short’. However, the hens had higher accuracy in the ‘RR’ conditions when the ‘back key’ was illuminated throughout sample presentation then when it was not (‘NR’ conditions). This suggests that the animals own behaviour improved their ability to time.

year: 2015

title: Assessment of the performance of a turbulence closure model: along the tidally-influenced Kaipara River to the estuary, NZ

authors: Dejeans, Bérengère S.

subjects: turbulence

abstract: The success of many coastal management projects hinges on the ability to predict the dispersal and settling of sediment particles. Hydrodynamic models have enabled the efficient simulation of sediment transport scenarios at large spatial scales and long time scales. However, these models have limited predictive capacity owing to an incomplete understanding of the processes involved. Turbulence has been shown to have a substantial influence on sediment transport by influencing flocculation (i.e. aggregation of particles), hence driving the behaviour of particles (e.g. deposition, erosion, mixing). Turbulence tends to promote aggregation at low shear stresses and cause floc breakups at high shear stresses. However, despite the key role of turbulence in coastal modelling, there is not a unique approach but several methods to describe turbulence, each based on a different combination of assumptions. We present modelling results exploring the performance of one closure scheme implemented in a hydrodynamic and sediment transport model, Delft3D. The assessment of the performance of the model is based on comparisons with measured data collected in the heavily sediment-laden Kaipara river, New Zealand. Data was collected in October 2013 using Lagrangian “flocdrifter” platforms released at multiple locations to capture both hydrodynamic and sediment data. In general the model was found to be able to reproduce the right order of magnitude of dissipation rates. However, turbulence characteristics in some sections of the river, usually in the vicinity of abrupt bends, are relatively poorly reproduced. Future work will aim to use the present model to improve the conceptual understanding of fundamental physical processes, in particular the effect of turbulence on flocculation, and floc formation and breakup in estuarine and riverine systems.

text: Assessment of the performance of a turbulence closure model: along the tidally-influenced Kaipara River to the estuary, NZ The success of many coastal management projects hinges on the ability to predict the dispersal and settling of sediment particles. Hydrodynamic models have enabled the efficient simulation of sediment transport scenarios at large spatial scales and long time scales. However, these models have limited predictive capacity owing to an incomplete understanding of the processes involved. Turbulence has been shown to have a substantial influence on sediment transport by influencing flocculation (i.e. aggregation of particles), hence driving the behaviour of particles (e.g. deposition, erosion, mixing). Turbulence tends to promote aggregation at low shear stresses and cause floc breakups at high shear stresses. However, despite the key role of turbulence in coastal modelling, there is not a unique approach but several methods to describe turbulence, each based on a different combination of assumptions. We present modelling results exploring the performance of one closure scheme implemented in a hydrodynamic and sediment transport model, Delft3D. The assessment of the performance of the model is based on comparisons with measured data collected in the heavily sediment-laden Kaipara river, New Zealand. Data was collected in October 2013 using Lagrangian “flocdrifter” platforms released at multiple locations to capture both hydrodynamic and sediment data. In general the model was found to be able to reproduce the right order of magnitude of dissipation rates. However, turbulence characteristics in some sections of the river, usually in the vicinity of abrupt bends, are relatively poorly reproduced. Future work will aim to use the present model to improve the conceptual understanding of fundamental physical processes, in particular the effect of turbulence on flocculation, and floc formation and breakup in estuarine and riverine systems.

year: 2017

title: Te Ahi Kā

authors: Temara, Pou

subjects: Ahi kā

abstract: Ko te urutaumatua o tēnei tuhinga, ko te matapaki i te ahi kā. He aha tēnei tikanga? I pēhea i ara ake ai? He aha ōna mātāpono, ōna taipitopito? Koia te tūāpapa mō te tuhinga nei. Tuarua, ko te wānanga i te tikanga Māori me ōna rerenga pērā i te whakapapa. Ko te pātai ka puta i tēnei wāhanga o te wānanga ko tēnei nā, he aha te wāhi o te whakapapa ki te ahi kā? Ko te ngako o tēnei tuhinga ko te wetewete i te tikanga ahi kā kia whai tikanga ai te whakataukī nei, ‘ko te ahi kā te mana o te hapū ki te whenua’.

text: Te Ahi Kā Ko te urutaumatua o tēnei tuhinga, ko te matapaki i te ahi kā. He aha tēnei tikanga? I pēhea i ara ake ai? He aha ōna mātāpono, ōna taipitopito? Koia te tūāpapa mō te tuhinga nei. Tuarua, ko te wānanga i te tikanga Māori me ōna rerenga pērā i te whakapapa. Ko te pātai ka puta i tēnei wāhanga o te wānanga ko tēnei nā, he aha te wāhi o te whakapapa ki te ahi kā? Ko te ngako o tēnei tuhinga ko te wetewete i te tikanga ahi kā kia whai tikanga ai te whakataukī nei, ‘ko te ahi kā te mana o te hapū ki te whenua’.

year: 2012-05