title: Propositionalisation of multi-instance data using random forests

authors: Frank, Eibe

subjects: Machine learning

abstract: Multi-instance learning is a generalisation of attribute-value learning where examples for learning consist of labeled bags (i.e. multi-sets) of instances. This learning setting is more computationally challenging than attribute-value learning and a natural fit for important application areas of machine learning such as classification of molecules and image classification. One approach to solve multi-instance learning problems is to apply propositionalisation, where bags of data are converted into vectors of attribute-value pairs so that a standard propositional (i.e. attribute-value) learning algorithm can be applied. This approach is attractive because of the large number of propositional learning algorithms that have been developed and can thus be applied to the propositionalised data. In this paper, we empirically investigate a variant of an existing propositionalisation method called TLC. TLC uses a single decision tree to obtain propositionalised data. Our variant applies a random forest instead and is motivated by the potential increase in robustness that this may yield. We present results on synthetic and real-world data from the above two application domains showing that it indeed yields increased classification accuracy when applying boosting and support vector machines to classify the propositionalised data.

text: Propositionalisation of multi-instance data using random forests Multi-instance learning is a generalisation of attribute-value learning where examples for learning consist of labeled bags (i.e. multi-sets) of instances. This learning setting is more computationally challenging than attribute-value learning and a natural fit for important application areas of machine learning such as classification of molecules and image classification. One approach to solve multi-instance learning problems is to apply propositionalisation, where bags of data are converted into vectors of attribute-value pairs so that a standard propositional (i.e. attribute-value) learning algorithm can be applied. This approach is attractive because of the large number of propositional learning algorithms that have been developed and can thus be applied to the propositionalised data. In this paper, we empirically investigate a variant of an existing propositionalisation method called TLC. TLC uses a single decision tree to obtain propositionalised data. Our variant applies a random forest instead and is motivated by the potential increase in robustness that this may yield. We present results on synthetic and real-world data from the above two application domains showing that it indeed yields increased classification accuracy when applying boosting and support vector machines to classify the propositionalised data.

year: 2013

title: Constraints on the thermal and tectonic evolution of Greymouth coalfield

authors: Kamp, Peter J.J.

subjects: Greymouth Coalfield

abstract: The southern end of the Paparoa Range in Westland, South Island, New Zealand, comprises an asymmetrical, southward plunging, faulted (Brunner-Mt Davy) anticline, the eastern limb of which is common with the western limb of an asymmetrical (Grey Valley) syncline forming a Neogene foreland basin (Grey Valley Trough). The faulted anticline is a classic inversion structure: compression during the Neogene, associated with the development of the modern Australia-Pacific plate boundary, caused a pre-existing normal fault zone, about which a late Cretaceous-Oligocene extensional half graben had formed (Paparoa Trough), to change its sense of displacement. The resulting basement loading formed the foreland basin, containing up to 3 km of mainly marine sedimentary section. 
Fission track results for apatite concentrates from 41 shallow drillhole and outcrop samples from the Greymouth Coalfield part of the Brunner-Mt Davy Anticline are reported and interpreted, to better establish the timing and amount of inversion, and hence the mechanism of inversion. The fission track results integrated with modelling of vitrinite reflectance data, show that the maximum paleotemperatures experienced during burial of the Late Cretaceous and mid-Eocene coal-bearing succession everywhere exceeded 85deg.C, and reached a peak of 180deg.C along the axis of the former basin. Cooling from maximum temperatures occurred during three discrete phases: 20-15 Ma, 12-7 Ma, and c. 2 Ma to the present. The amount of denudation has been variable across the inverted basin, decreasing westward from a maximum of c. 2.5 km during the first deformation phase, c. 1.2 km during the second phase, and 1.4 km during the third phase. It appears that exhumation over the coalfield continued for about 2 m.y. beyond the biostratigraphically determined time ranges of each of two synorogenic unconformities along the western limb of the Grey Valley Syncline. Stick-slip behaviour on the range front fault that localised the inversion is inferred. The tectonic evolution of the anticline-syncline pair at the southern end of the Paparoa Range, is therefore identical in style, and similar in timing, to the development of the Papahaua Range-Westport Trough across the Kongahu Fault Zone, in the vicinity of Buller Coalfield.

text: Constraints on the thermal and tectonic evolution of Greymouth coalfield The southern end of the Paparoa Range in Westland, South Island, New Zealand, comprises an asymmetrical, southward plunging, faulted (Brunner-Mt Davy) anticline, the eastern limb of which is common with the western limb of an asymmetrical (Grey Valley) syncline forming a Neogene foreland basin (Grey Valley Trough). The faulted anticline is a classic inversion structure: compression during the Neogene, associated with the development of the modern Australia-Pacific plate boundary, caused a pre-existing normal fault zone, about which a late Cretaceous-Oligocene extensional half graben had formed (Paparoa Trough), to change its sense of displacement. The resulting basement loading formed the foreland basin, containing up to 3 km of mainly marine sedimentary section. 
Fission track results for apatite concentrates from 41 shallow drillhole and outcrop samples from the Greymouth Coalfield part of the Brunner-Mt Davy Anticline are reported and interpreted, to better establish the timing and amount of inversion, and hence the mechanism of inversion. The fission track results integrated with modelling of vitrinite reflectance data, show that the maximum paleotemperatures experienced during burial of the Late Cretaceous and mid-Eocene coal-bearing succession everywhere exceeded 85deg.C, and reached a peak of 180deg.C along the axis of the former basin. Cooling from maximum temperatures occurred during three discrete phases: 20-15 Ma, 12-7 Ma, and c. 2 Ma to the present. The amount of denudation has been variable across the inverted basin, decreasing westward from a maximum of c. 2.5 km during the first deformation phase, c. 1.2 km during the second phase, and 1.4 km during the third phase. It appears that exhumation over the coalfield continued for about 2 m.y. beyond the biostratigraphically determined time ranges of each of two synorogenic unconformities along the western limb of the Grey Valley Syncline. Stick-slip behaviour on the range front fault that localised the inversion is inferred. The tectonic evolution of the anticline-syncline pair at the southern end of the Paparoa Range, is therefore identical in style, and similar in timing, to the development of the Papahaua Range-Westport Trough across the Kongahu Fault Zone, in the vicinity of Buller Coalfield.

year: 1999

title: Spatial and temporal characteristics of the underwater soundscape around the Motiti Protection Area: Ōtaiti/Astrolabe Reef and Motiti Island

authors: Riegel, Maria Sophie

subjects: Underwater Soundscapes

abstract: Marine ecosystems around the world have been impacted by degradation and loss of biodiversity as a result of human impacts and climate change. The monitoring and management of ecologically significant areas is vital in understanding the effects of habitat degradation on marine ecosystems. Traditional monitoring methods are often expensive, time consuming, labour intensive and invasive. Soundscapes offer a unique opportunity for monitoring habitats in a way that is cost effective, minimally invasive and efficient. The aim of this study was to use passive acoustic monitoring to create a baseline data set using ambient sound data to investigate the spatial and temporal changes in ambient sound pressure levels, and to identify biotic, abiotic and anthropogenic sound sources which make up the marine soundscapes at the Motiti Island and Ōtaiti/Astrolabe Reef. Five diverse and ecologically significant sites in the Motiti Protection Area – at Ōtaiti/Astrolabe Reef and Motiti Island, in the Bay of Plenty, New Zealand were selected and monitored over the course of a year. This provided a wide variety of data to show the diel, lunar and seasonal patterns and trends in acoustic biological activity in order to represent the ecosystems accurately. The results showed that all sites showed strong diel patterns, with a sound pressure level increase of ~6-10dB during daylight hours compared to dark hours, and evident peaks during dawn and dusk hours as a result of biological choruses composed largely of sea urchins. There were also strong seasonal trends among the five sites, with Summer having the overall highest sound pressure level compared to Spring, Autumn and Winter, this also had an effect on the peaks in dusk choruses, which were also found to be highest during Summer. Lunar phases were also found to have an impact on the sound pressure levels of all five sites, with increased sound pressure levels during the new moon, compared to sound pressure levels during the full moon. This study created a baseline data set for a culturally, ecologically, and economically valuable area. Passive acoustic monitoring was found to be an incredibly useful tool in understand the ecosystems health and biological condition, and offers an alternative to traditional monitoring which is an effective, minimally invasive, and less labour intensive way of monitoring marine ecosystems.

text: Spatial and temporal characteristics of the underwater soundscape around the Motiti Protection Area: Ōtaiti/Astrolabe Reef and Motiti Island Marine ecosystems around the world have been impacted by degradation and loss of biodiversity as a result of human impacts and climate change. The monitoring and management of ecologically significant areas is vital in understanding the effects of habitat degradation on marine ecosystems. Traditional monitoring methods are often expensive, time consuming, labour intensive and invasive. Soundscapes offer a unique opportunity for monitoring habitats in a way that is cost effective, minimally invasive and efficient. The aim of this study was to use passive acoustic monitoring to create a baseline data set using ambient sound data to investigate the spatial and temporal changes in ambient sound pressure levels, and to identify biotic, abiotic and anthropogenic sound sources which make up the marine soundscapes at the Motiti Island and Ōtaiti/Astrolabe Reef. Five diverse and ecologically significant sites in the Motiti Protection Area – at Ōtaiti/Astrolabe Reef and Motiti Island, in the Bay of Plenty, New Zealand were selected and monitored over the course of a year. This provided a wide variety of data to show the diel, lunar and seasonal patterns and trends in acoustic biological activity in order to represent the ecosystems accurately. The results showed that all sites showed strong diel patterns, with a sound pressure level increase of ~6-10dB during daylight hours compared to dark hours, and evident peaks during dawn and dusk hours as a result of biological choruses composed largely of sea urchins. There were also strong seasonal trends among the five sites, with Summer having the overall highest sound pressure level compared to Spring, Autumn and Winter, this also had an effect on the peaks in dusk choruses, which were also found to be highest during Summer. Lunar phases were also found to have an impact on the sound pressure levels of all five sites, with increased sound pressure levels during the new moon, compared to sound pressure levels during the full moon. This study created a baseline data set for a culturally, ecologically, and economically valuable area. Passive acoustic monitoring was found to be an incredibly useful tool in understand the ecosystems health and biological condition, and offers an alternative to traditional monitoring which is an effective, minimally invasive, and less labour intensive way of monitoring marine ecosystems.

year: 2022