title: Scaling up semi-supervised learning: An efficient and effective LLGC variant

authors: Pfahringer, Bernhard

subjects: computer science

abstract: Domains like text classification can easily supply large amounts of unlabeled data, but labeling itself is expensive. Semi- supervised learning tries to exploit this abundance of unlabeled training data to improve classification. Unfortunately most of the theoretically well-founded algorithms that have been described in recent years are cubic or worse in the total number of both labeled and unlabeled training examples. In this paper we apply modifications to the standard LLGC algorithm to improve efficiency to a point where we can handle datasets with hundreds of thousands of training data. The modifications are priming of the unlabeled data, and most importantly, sparsification of the similarity matrix. We report promising results on large text classification problems.

text: Scaling up semi-supervised learning: An efficient and effective LLGC variant Domains like text classification can easily supply large amounts of unlabeled data, but labeling itself is expensive. Semi- supervised learning tries to exploit this abundance of unlabeled training data to improve classification. Unfortunately most of the theoretically well-founded algorithms that have been described in recent years are cubic or worse in the total number of both labeled and unlabeled training examples. In this paper we apply modifications to the standard LLGC algorithm to improve efficiency to a point where we can handle datasets with hundreds of thousands of training data. The modifications are priming of the unlabeled data, and most importantly, sparsification of the similarity matrix. We report promising results on large text classification problems.

year: 2007

title: Does seagrass influence the behavioural and physiological response to flow in juvenile snapper (Pagrus auratus)?

authors: Cooper, Jordan

subjects: Seagrass habitats

abstract: Many juvenile fish species are associated with structural habitats, potentially benefiting them from reduced predation and competition as well as enhanced feeding opportunities. It is also possible that structural habitats may provide a refuge from flow. Research on juvenile snapper in New Zealand has largely focused on their habitat preference. Juvenile snapper (Pagrus auratus) have been observed in close proximity to seagrass (Zostera muelleri) in New Zealand estuaries and I tested whether this association offered a refuge from flow. In an annular flume I exposed two cohorts of juvenile snapper 4.1 ± 0.5 cm and 8.9 ± 0.7 cm in length to sequential increases of flow speed (approximately 1 body length per second every 15 minutes). Flow speed increased at 3 cm s⁻¹ every 15 minutes for the smaller cohort of juvenile snapper, and 8 cm s⁻¹ for the larger cohort of juvenile snapper. Juvenile snapper were exposed to three treatments comprising of; bare, mixed (seagrass, bare and edge habitat) and full seagrass coverage. Fish behaviour was observed and critical swimming speed (Ucrit) estimated (i.e. the flow at which fish can no longer maintain position). Juvenile snapper were exposed to flow speeds that are representative of current flows in New Zealand estuaries and harbours. A startle response was recorded at the end as an indicator of fatigue and from larger juveniles a blood sample was collected via caudal puncture to determine if there were any physiological advantages offered by seagrass, by analysing stress indicators (based on lactate, triglyceride, glucose, haemoglobin and haematocrit).

Velocity profiles indicated that the seagrass treatment and sampling points 2 (seagrass upstream and downstream) and 9 (5 cm into the leading edge of seagrass) from the mixed treatment dampened the flow speed within the annular flume. This result may be responsible for the increased percentage of time spent utilising the edge habitat as flow velocity increased, indicating that juvenile snapper seek refuge from high flows in or on the leading edge of seagrass patches. These results are consistent with an increase in critical swimming speed with increasing seagrass coverage (smaller juvenile snapper – bare = 19.47, mixed = 21.13, seagrass = 21.66 cm s⁻¹) (larger juvenile snapper – bare = 52.23, mixed = 58.89, seagrass = 60.31 cm s⁻¹). Physiological indicators, triglyceride, yielded significant differences between the bare treatment (1.40 mM) compared to the mixed (1.05 mM) and seagrass (1.01 mM) treatments, suggesting that energy stores were more readily utilised as energy expenditure increased where structural complexity was absent. The bare treatment also produced the highest values for both lactate and glucose, however, results were not significant. Mean cell haemoglobin concentration and total haemoglobin concentration did not yield significant differences between treatments. Whilst producing positive trends, results suggest that the effect of structural complexity was subtle in the annular flume. These findings have important implications for other hypotheses to explain the association between juvenile snapper and seagrass beds.

text: Does seagrass influence the behavioural and physiological response to flow in juvenile snapper (Pagrus auratus)? Many juvenile fish species are associated with structural habitats, potentially benefiting them from reduced predation and competition as well as enhanced feeding opportunities. It is also possible that structural habitats may provide a refuge from flow. Research on juvenile snapper in New Zealand has largely focused on their habitat preference. Juvenile snapper (Pagrus auratus) have been observed in close proximity to seagrass (Zostera muelleri) in New Zealand estuaries and I tested whether this association offered a refuge from flow. In an annular flume I exposed two cohorts of juvenile snapper 4.1 ± 0.5 cm and 8.9 ± 0.7 cm in length to sequential increases of flow speed (approximately 1 body length per second every 15 minutes). Flow speed increased at 3 cm s⁻¹ every 15 minutes for the smaller cohort of juvenile snapper, and 8 cm s⁻¹ for the larger cohort of juvenile snapper. Juvenile snapper were exposed to three treatments comprising of; bare, mixed (seagrass, bare and edge habitat) and full seagrass coverage. Fish behaviour was observed and critical swimming speed (Ucrit) estimated (i.e. the flow at which fish can no longer maintain position). Juvenile snapper were exposed to flow speeds that are representative of current flows in New Zealand estuaries and harbours. A startle response was recorded at the end as an indicator of fatigue and from larger juveniles a blood sample was collected via caudal puncture to determine if there were any physiological advantages offered by seagrass, by analysing stress indicators (based on lactate, triglyceride, glucose, haemoglobin and haematocrit).

Velocity profiles indicated that the seagrass treatment and sampling points 2 (seagrass upstream and downstream) and 9 (5 cm into the leading edge of seagrass) from the mixed treatment dampened the flow speed within the annular flume. This result may be responsible for the increased percentage of time spent utilising the edge habitat as flow velocity increased, indicating that juvenile snapper seek refuge from high flows in or on the leading edge of seagrass patches. These results are consistent with an increase in critical swimming speed with increasing seagrass coverage (smaller juvenile snapper – bare = 19.47, mixed = 21.13, seagrass = 21.66 cm s⁻¹) (larger juvenile snapper – bare = 52.23, mixed = 58.89, seagrass = 60.31 cm s⁻¹). Physiological indicators, triglyceride, yielded significant differences between the bare treatment (1.40 mM) compared to the mixed (1.05 mM) and seagrass (1.01 mM) treatments, suggesting that energy stores were more readily utilised as energy expenditure increased where structural complexity was absent. The bare treatment also produced the highest values for both lactate and glucose, however, results were not significant. Mean cell haemoglobin concentration and total haemoglobin concentration did not yield significant differences between treatments. Whilst producing positive trends, results suggest that the effect of structural complexity was subtle in the annular flume. These findings have important implications for other hypotheses to explain the association between juvenile snapper and seagrass beds.

year: 2015

title: Te Poho o Te Arawa: Te Mana Whenua o Ngāti Whakaue ki Maketū

authors: Potaka, Ngahu

subjects: Ngāti Whakaue

abstract: Maketū is a small coastal town in the Bay of Plenty and is the final resting place of the Te Arawa canoe, the ancestral waka of the Te Arawa people. This is the home of Ngāti Whakaue ki Maketū a coastal hapū of the tribe Ngāti Whakaue from the Te Arawa confederation of tribes. Ngāti Whakaue ki Maketū is actually a collection of smaller hapū who descend from the union of their ancestor Whakaue Kaipapa and his wife Rangiuru, and they trace their overall decent from the celebrated chief Tama te Kapua. It is on their ancestral land in Maketū that Ngāti Whakaue ki Maketū have resided and established their mana whenua (tribal authority) for over 170 years. In that time they have faced many internal and external challenges to their mana whenua including military engagement, political maneuvering, and other social issues.

This thesis traces the historical origins and mana whenua of Ngāti Whakaue ki Maketū and analyses the various key components that combine to ensure Ngāti Whakaue ki Maketū maintain mana whenua across their tribal lands. This thesis also explores how mana whenua is a vehicle for maintaining tribal authority and well being for Ngāti Whakaue ki Maketū. Part of this study is the creation of a mana whenua strategic plan that will help Ngāti Whakaue ki Maketū maintain and secure mana whenua in Maketū for future generations.

It is the proposition of this thesis that mana whenua has, is and will always play an important part in the social identity and fabric of Ngati Whakaue ki Maketū. However as Ngāti Whakaue ki Maketū stand at the dawn of a new era, it is important for this related group to understand how mana whenua operates, and can be nurtured as a means of protection to ensure the survival of Ngāti Whakaue ki Maketū in this ever changing world.

text: Te Poho o Te Arawa: Te Mana Whenua o Ngāti Whakaue ki Maketū Maketū is a small coastal town in the Bay of Plenty and is the final resting place of the Te Arawa canoe, the ancestral waka of the Te Arawa people. This is the home of Ngāti Whakaue ki Maketū a coastal hapū of the tribe Ngāti Whakaue from the Te Arawa confederation of tribes. Ngāti Whakaue ki Maketū is actually a collection of smaller hapū who descend from the union of their ancestor Whakaue Kaipapa and his wife Rangiuru, and they trace their overall decent from the celebrated chief Tama te Kapua. It is on their ancestral land in Maketū that Ngāti Whakaue ki Maketū have resided and established their mana whenua (tribal authority) for over 170 years. In that time they have faced many internal and external challenges to their mana whenua including military engagement, political maneuvering, and other social issues.

This thesis traces the historical origins and mana whenua of Ngāti Whakaue ki Maketū and analyses the various key components that combine to ensure Ngāti Whakaue ki Maketū maintain mana whenua across their tribal lands. This thesis also explores how mana whenua is a vehicle for maintaining tribal authority and well being for Ngāti Whakaue ki Maketū. Part of this study is the creation of a mana whenua strategic plan that will help Ngāti Whakaue ki Maketū maintain and secure mana whenua in Maketū for future generations.

It is the proposition of this thesis that mana whenua has, is and will always play an important part in the social identity and fabric of Ngati Whakaue ki Maketū. However as Ngāti Whakaue ki Maketū stand at the dawn of a new era, it is important for this related group to understand how mana whenua operates, and can be nurtured as a means of protection to ensure the survival of Ngāti Whakaue ki Maketū in this ever changing world.

year: 2014