title: Reproductive Biology and Ecology of the Endemic New Zealand Tree Ixerba brexioides (tāwari)

authors: Thomson, Rachel Elizabeth

subjects: Ixerba brexioides

abstract: This research investigated the ecology of Ixerba brexioides (tāwari) with regard to pollination, breeding strategy, seed biology, and forest composition. Research was focused around three main questions:
1.	How is tāwari pollinated with regard to vector and pollen source? How is it adapted for this?
2.	How is seed dispersal of tāwari achieved and under what conditions is germination most successful?
3.	What are the dominant community associations of tāwari what how are they constrained by environmental variables?
The first research question was addressed using video surveillance, nectar analysis, and artificial pollination experiments in a small tract of tāwari forest at Tūī Ridge Park in the Mamaku Range, North Island, New Zealand. Analysis of 125 hours of video footage showed that tāwari is predominantly insect pollinated with occasional bird visitation. The most frequent flower visitors were flies and nocturnal moths. Tāwari nectar volume peaked at midday, and declined toward the late afternoon, before increasing again at dusk. This pattern of nectar secretion followed closely the activity patterns of flies during the day and moths at night. Nectar sugar concentration was 11% on average (range 3% to 20%) which is considered low, but is suited to moths, bats, birds, and bees. Exclusion experiments demonstrated that tāwari is capable of producing viable seed under cross-fertilisation, self-fertilisation, and agamospermy. Breeding system indices demonstrated that tāwari is medium pollen limited (PLI = 0.31), self-compatible (SCI = 0.93), and autonomously selfing (ASI = 0.65).
Question two was addressed by video surveillance of tāwari seed capsules, morphological observation, and by a series of germination experiments. Video failure meant that with limited footage (mostly at night) no dispersal activity was captured on film. However, using available literature and observations of seed morphology birds were considered the most probable effective disperser. Germination trials included standard conditions, shade, seeds left in fruit, seeds deposited on soil surface, and seeds buried at 5 cm soil depth. Germination was most effective in the buried treatment (average 85% germination) and the soil surface treatment (average 75% germination).
Cluster analysis and NMS (Non-Metric Multi-Dimensional Scaling) ordination of 641 plots of tāwari forest from the NVS (National Vegetation Survey) database was used to assess the community associations of tāwari. Based on plot species assemblage, the analysis showed four main forest types that are largely separate in geographical space: Northland, Coromandel, Kaimai, and Urewera. Each type had significant indicator species that were constrained in range by latitudinal limits. Recent literature suggests that environmental variables that most influence tāwari forest distribution are annual temperature and rainfall in conjunction with solar radiation. Tāwari forest occupies only areas which are cool and moist, and seedlings are biased toward high light conditions. In the central North Island tāwari had the highest probability of occurrence in sites with a mean annual temperature of 11° to 13° Celsius, mean annual rainfall between 2000 and 2250 mm annually, and mean solar radiation of 143 to 145 MJ m2 per day. Parent material also plays an important part, especially the depth of Taupō Pumice deposits as tāwari forest is more prone to occur in areas of mature soil where depth of volcanic deposits is not excessive. 
Information on tāwari from the present thesis combined with other published and unpublished sources is presented in the form of a New Zealand Biological Flora Series journal contribution.
Recommendations for further research on tāwari and New Zealand reproductive biology in general are given.

text: Reproductive Biology and Ecology of the Endemic New Zealand Tree Ixerba brexioides (tāwari) This research investigated the ecology of Ixerba brexioides (tāwari) with regard to pollination, breeding strategy, seed biology, and forest composition. Research was focused around three main questions:
1.	How is tāwari pollinated with regard to vector and pollen source? How is it adapted for this?
2.	How is seed dispersal of tāwari achieved and under what conditions is germination most successful?
3.	What are the dominant community associations of tāwari what how are they constrained by environmental variables?
The first research question was addressed using video surveillance, nectar analysis, and artificial pollination experiments in a small tract of tāwari forest at Tūī Ridge Park in the Mamaku Range, North Island, New Zealand. Analysis of 125 hours of video footage showed that tāwari is predominantly insect pollinated with occasional bird visitation. The most frequent flower visitors were flies and nocturnal moths. Tāwari nectar volume peaked at midday, and declined toward the late afternoon, before increasing again at dusk. This pattern of nectar secretion followed closely the activity patterns of flies during the day and moths at night. Nectar sugar concentration was 11% on average (range 3% to 20%) which is considered low, but is suited to moths, bats, birds, and bees. Exclusion experiments demonstrated that tāwari is capable of producing viable seed under cross-fertilisation, self-fertilisation, and agamospermy. Breeding system indices demonstrated that tāwari is medium pollen limited (PLI = 0.31), self-compatible (SCI = 0.93), and autonomously selfing (ASI = 0.65).
Question two was addressed by video surveillance of tāwari seed capsules, morphological observation, and by a series of germination experiments. Video failure meant that with limited footage (mostly at night) no dispersal activity was captured on film. However, using available literature and observations of seed morphology birds were considered the most probable effective disperser. Germination trials included standard conditions, shade, seeds left in fruit, seeds deposited on soil surface, and seeds buried at 5 cm soil depth. Germination was most effective in the buried treatment (average 85% germination) and the soil surface treatment (average 75% germination).
Cluster analysis and NMS (Non-Metric Multi-Dimensional Scaling) ordination of 641 plots of tāwari forest from the NVS (National Vegetation Survey) database was used to assess the community associations of tāwari. Based on plot species assemblage, the analysis showed four main forest types that are largely separate in geographical space: Northland, Coromandel, Kaimai, and Urewera. Each type had significant indicator species that were constrained in range by latitudinal limits. Recent literature suggests that environmental variables that most influence tāwari forest distribution are annual temperature and rainfall in conjunction with solar radiation. Tāwari forest occupies only areas which are cool and moist, and seedlings are biased toward high light conditions. In the central North Island tāwari had the highest probability of occurrence in sites with a mean annual temperature of 11° to 13° Celsius, mean annual rainfall between 2000 and 2250 mm annually, and mean solar radiation of 143 to 145 MJ m2 per day. Parent material also plays an important part, especially the depth of Taupō Pumice deposits as tāwari forest is more prone to occur in areas of mature soil where depth of volcanic deposits is not excessive. 
Information on tāwari from the present thesis combined with other published and unpublished sources is presented in the form of a New Zealand Biological Flora Series journal contribution.
Recommendations for further research on tāwari and New Zealand reproductive biology in general are given.

year: 2013

title: Guarded operations, refinement and simulation

authors: Reeves, Steve

subjects: computer science

abstract: Simulation rules have long been used as an effective computational means to decide refinement relations in state-based formalisms. Here we investigate how they might be amended so as to decide the event-based notion of singleton failures refinement of abstract data types, or processes, that have operations with a “guarded” interpretation.

text: Guarded operations, refinement and simulation Simulation rules have long been used as an effective computational means to decide refinement relations in state-based formalisms. Here we investigate how they might be amended so as to decide the event-based notion of singleton failures refinement of abstract data types, or processes, that have operations with a “guarded” interpretation.

year: 2009

title: Geographical and ethnic differences of osteoarthritis-associated hip and knee replacement surgeries in New Zealand: a population-based cross-sectional study

authors: Lao, Chunhuan

abstract: Objectives To (1) explore the regional and ethnic differences in rates of publicly funded osteoarthritis-associated hip and knee replacement surgeries and (2) investigate the mortality after surgery.

Design Population-based, retrospective, cross-sectional study.

Setting General population in New Zealand.

Participants Patients with osteoarthritis who underwent publicly funded primary hip and knee replacement surgeries in 2005–2017. Patients aged 14–99 years were included.

Primary and secondary outcome measures Age-standardised rate, standardised mortality ratio (SMR) and 30 days, 90 days and 1 year mortality.

Results We identified 53 439 primary hip replacements and 50 072 primary knee replacements with a diagnosis of osteoarthritis. The number and age-standardised rates of hip and knee replacements increased over time. Māori had the highest age-standardised rate of hip replacements, followed by European/others and Pacific, and Asian had the lowest rate. Pacific had the highest age-standardised rate of knee replacements, followed by Māori and European/others, and Asian had the lowest rate. The Northern Health Network had the lowest rate of hip surgeries, and the Southern Health Network had the lowest rate of knee surgeries. The SMRs of patients undergoing hip and knee replacements were lower than the general population: 0.92 (95% CI 0.89 to 0.95) for hip and 0.79 (95% CI 0.76 to 0.82) for knee. The SMRs were decreasing over time. The patterns of 30 days, 90 days and 1 year mortality were similar to the SMR.

Conclusions The numbers of publicly funded osteoarthritis-associated primary hip and knee replacements are steadily increasing. Māori people had the highest age-standardised rate of hip replacements and Pacific people had the highest rate of knee replacements. The Northern Health Network had the lowest rate of hip surgeries, and the Southern Health Network had the lowest rate of knee surgeries. Compared with the general population, patients who had hip and knee replacements have a better life expectancy.

text: Geographical and ethnic differences of osteoarthritis-associated hip and knee replacement surgeries in New Zealand: a population-based cross-sectional study Objectives To (1) explore the regional and ethnic differences in rates of publicly funded osteoarthritis-associated hip and knee replacement surgeries and (2) investigate the mortality after surgery.

Design Population-based, retrospective, cross-sectional study.

Setting General population in New Zealand.

Participants Patients with osteoarthritis who underwent publicly funded primary hip and knee replacement surgeries in 2005–2017. Patients aged 14–99 years were included.

Primary and secondary outcome measures Age-standardised rate, standardised mortality ratio (SMR) and 30 days, 90 days and 1 year mortality.

Results We identified 53 439 primary hip replacements and 50 072 primary knee replacements with a diagnosis of osteoarthritis. The number and age-standardised rates of hip and knee replacements increased over time. Māori had the highest age-standardised rate of hip replacements, followed by European/others and Pacific, and Asian had the lowest rate. Pacific had the highest age-standardised rate of knee replacements, followed by Māori and European/others, and Asian had the lowest rate. The Northern Health Network had the lowest rate of hip surgeries, and the Southern Health Network had the lowest rate of knee surgeries. The SMRs of patients undergoing hip and knee replacements were lower than the general population: 0.92 (95% CI 0.89 to 0.95) for hip and 0.79 (95% CI 0.76 to 0.82) for knee. The SMRs were decreasing over time. The patterns of 30 days, 90 days and 1 year mortality were similar to the SMR.

Conclusions The numbers of publicly funded osteoarthritis-associated primary hip and knee replacements are steadily increasing. Māori people had the highest age-standardised rate of hip replacements and Pacific people had the highest rate of knee replacements. The Northern Health Network had the lowest rate of hip surgeries, and the Southern Health Network had the lowest rate of knee surgeries. Compared with the general population, patients who had hip and knee replacements have a better life expectancy.

year: 2019