title: SIFTing the relevant from the irrelevant: Automatically detecting objects in training images

authors: Zhang, Edmond Yiwen

subjects: Image processing

abstract: Many state-of-the-art object recognition systems rely on identifying the location of objects in images, in order to better learn its visual attributes. In this paper, we propose four simple yet powerful hybrid ROI detection methods (combining both local and global features), based on frequently occurring keypoints. We show that our methods demonstrate competitive performance in two different types of datasets, the Caltech101 dataset and the GRAZ-02 dataset, where the pairs of keypoint bounding box method achieved the best accuracies overall.

text: SIFTing the relevant from the irrelevant: Automatically detecting objects in training images Many state-of-the-art object recognition systems rely on identifying the location of objects in images, in order to better learn its visual attributes. In this paper, we propose four simple yet powerful hybrid ROI detection methods (combining both local and global features), based on frequently occurring keypoints. We show that our methods demonstrate competitive performance in two different types of datasets, the Caltech101 dataset and the GRAZ-02 dataset, where the pairs of keypoint bounding box method achieved the best accuracies overall.

year: 2009

title: Long-term variations in fish assemblage, macrophyte community, and water quality in Lake Rotoroa (Hamilton Lake)

authors: Law, Duncan Robert Mckenzie

abstract: Lake Rotoroa (37º48’S, 175º16’E) is a small, shallow, polymictic lake located on the western side of Hamilton City. The lake covers an area of 0.54 km2 with a mean depth of 2.4 m, catchment and riparian margins have been significantly modified into a suburban park-like setting. Due to its urban location and recreational value, exotic flora and fauna have been intentionally and unintentionally introduced. This has resulted in fluctuations in water quality and changes in phytoplankton, fish, and macrophyte assemblages over the past 60 years. The overall aim of this thesis is to summarise the fluctuations in water quality and macrophyte community of Lake Rotoroa associated with introduction of exotic species, and to develop a general understanding of the ecosystem response. This study involved collating and analysing available information on fish assemblages, macrophyte community, and water quality in Lake Rotoroa. Data from nine fish surveys undertaken between 1976 and 2012 has been combined. Water quality and macrophyte data was supplied by NIWA, who have undertaken monitoring for Hamilton City Council as part of the national lakes monitoring programme.

Fishing methods have varied from gill, trap, and fyke netting between 1976 and 2001, with boat electrofishing surveys between 2003 and 2012. Lake Rotoroa has a relatively diverse freshwater fish fauna, comprising two native and six exotic fish species. The fish assemblage is now dominated by the native shortfin eel (Anguilla australis), European perch (Perca fluviatilis), brown bullhead catfish (Ameiurus nebulosus), and tench (Tinca tinca), with low densities of rudd (Scardinius erythrophthalmus) and goldfish (Carassius auratus). Fish density and biomass have varied throughout the survey period, to some extent related to the environmental conditions and macrophyte cover. 

Macrophyte coverage and water quality have undergone considerable changes in the last 30 years, with the collapses of macrophytes stimulating decreases in water quality and increased perch abundance. In 1990, the macrophyte community collapsed with an associated release of nutrients into the water column, causing the lake to become supertrophic. Between 1992 and 2010, water quality improved, with a decrease phosphorus concentrations that apparently limited phytoplankton biomass and improved water clarity. This allowed macrophytes to recolonise the lake to 30% lake bed coverage in 2005 and a consequent improvement from supertrophic to a eutrophic state. Since 2009, the macrophyte community has undergone another collapse, with only a few clumps of native charophytes and Egeria densa present in 2011. The reduction of macrophytes has been accompanied by a decrease in water clarity. The collapse has been attributed to disturbance by grazing from the herbivorous rudd and foraging benthic feeding fish, although other stresses such as decreased water clarity and microcystins may also have had an influence. 

Further research is needed on the selectivity between passive and active fish capture methods used to allow accurate comparisons between the two methods. This will allow for density and biomass estimates to be made for the passive fishing methods previously used and allow greater insight into changes in abundance of fish populations in Lake Rotoroa.

text: Long-term variations in fish assemblage, macrophyte community, and water quality in Lake Rotoroa (Hamilton Lake) Lake Rotoroa (37º48’S, 175º16’E) is a small, shallow, polymictic lake located on the western side of Hamilton City. The lake covers an area of 0.54 km2 with a mean depth of 2.4 m, catchment and riparian margins have been significantly modified into a suburban park-like setting. Due to its urban location and recreational value, exotic flora and fauna have been intentionally and unintentionally introduced. This has resulted in fluctuations in water quality and changes in phytoplankton, fish, and macrophyte assemblages over the past 60 years. The overall aim of this thesis is to summarise the fluctuations in water quality and macrophyte community of Lake Rotoroa associated with introduction of exotic species, and to develop a general understanding of the ecosystem response. This study involved collating and analysing available information on fish assemblages, macrophyte community, and water quality in Lake Rotoroa. Data from nine fish surveys undertaken between 1976 and 2012 has been combined. Water quality and macrophyte data was supplied by NIWA, who have undertaken monitoring for Hamilton City Council as part of the national lakes monitoring programme.

Fishing methods have varied from gill, trap, and fyke netting between 1976 and 2001, with boat electrofishing surveys between 2003 and 2012. Lake Rotoroa has a relatively diverse freshwater fish fauna, comprising two native and six exotic fish species. The fish assemblage is now dominated by the native shortfin eel (Anguilla australis), European perch (Perca fluviatilis), brown bullhead catfish (Ameiurus nebulosus), and tench (Tinca tinca), with low densities of rudd (Scardinius erythrophthalmus) and goldfish (Carassius auratus). Fish density and biomass have varied throughout the survey period, to some extent related to the environmental conditions and macrophyte cover. 

Macrophyte coverage and water quality have undergone considerable changes in the last 30 years, with the collapses of macrophytes stimulating decreases in water quality and increased perch abundance. In 1990, the macrophyte community collapsed with an associated release of nutrients into the water column, causing the lake to become supertrophic. Between 1992 and 2010, water quality improved, with a decrease phosphorus concentrations that apparently limited phytoplankton biomass and improved water clarity. This allowed macrophytes to recolonise the lake to 30% lake bed coverage in 2005 and a consequent improvement from supertrophic to a eutrophic state. Since 2009, the macrophyte community has undergone another collapse, with only a few clumps of native charophytes and Egeria densa present in 2011. The reduction of macrophytes has been accompanied by a decrease in water clarity. The collapse has been attributed to disturbance by grazing from the herbivorous rudd and foraging benthic feeding fish, although other stresses such as decreased water clarity and microcystins may also have had an influence. 

Further research is needed on the selectivity between passive and active fish capture methods used to allow accurate comparisons between the two methods. This will allow for density and biomass estimates to be made for the passive fishing methods previously used and allow greater insight into changes in abundance of fish populations in Lake Rotoroa.

year: 2012

title: Insecure, unpredictable, hoping to survive: Four cases of Māori people living precariously in Hamilton, Aotearoa New Zealand

authors: Uerata, Lynley Moana

subjects: Māori

abstract: A conceptualisation of precarity is introduced and adopted. A critique of contemporary conceptualisations of precarity is presented, drawing especially on Stuart Hall’s interpretation of articulation and Marx’s concept of relative surplus population. Much of the literature on precarity focusses on the neoliberal mode of contemporary capitalism originating in the late 1970s. However, there is limited literature which explores precarity as a way of life. A precarious way of life is characterised by interacting forms of precarity which embed insecurity, instability, and unpredictability in the everyday lives of real people. An account of the Māori experience of precarity since the pre-colonial era to the present-day is presented. Māori are the indigenous people of Aotearoa New Zealand who were colonised by the British Empire in the 1800s. 
The main research questions addressed in my thesis are: What forms of precarity are present in the everyday context? How do forms of precarity relate to each other? How do forms of precarity relate to being Māori? What kinds of support do those living with precarity gain from social structures, institutions, and social actors? What is the role of culture in the way Māori experience and mediate precarity? An analysis of semi-structured in-depth engagements with Māori people living precariously in Hamilton, Aotearoa New Zealand in 2016, based on four case studies, shows the character and significance of forms, sources, and effects of precarity in everyday life. As historical processes continue to overdetermine experiences of social structures and institutions in the present, in a contemporary capitalist context precarity arises from a wide range of interacting sources, forms, and effects of precarity. Among the different kinds of actors and organisations which comprise the support systems constructed to mediate precarity in the everyday context, cultural practices and resources can play a significant role for people who are culturally connected. When people are integrated into their local and cultural communities, they can cope better with a precarious way of life.

text: Insecure, unpredictable, hoping to survive: Four cases of Māori people living precariously in Hamilton, Aotearoa New Zealand A conceptualisation of precarity is introduced and adopted. A critique of contemporary conceptualisations of precarity is presented, drawing especially on Stuart Hall’s interpretation of articulation and Marx’s concept of relative surplus population. Much of the literature on precarity focusses on the neoliberal mode of contemporary capitalism originating in the late 1970s. However, there is limited literature which explores precarity as a way of life. A precarious way of life is characterised by interacting forms of precarity which embed insecurity, instability, and unpredictability in the everyday lives of real people. An account of the Māori experience of precarity since the pre-colonial era to the present-day is presented. Māori are the indigenous people of Aotearoa New Zealand who were colonised by the British Empire in the 1800s. 
The main research questions addressed in my thesis are: What forms of precarity are present in the everyday context? How do forms of precarity relate to each other? How do forms of precarity relate to being Māori? What kinds of support do those living with precarity gain from social structures, institutions, and social actors? What is the role of culture in the way Māori experience and mediate precarity? An analysis of semi-structured in-depth engagements with Māori people living precariously in Hamilton, Aotearoa New Zealand in 2016, based on four case studies, shows the character and significance of forms, sources, and effects of precarity in everyday life. As historical processes continue to overdetermine experiences of social structures and institutions in the present, in a contemporary capitalist context precarity arises from a wide range of interacting sources, forms, and effects of precarity. Among the different kinds of actors and organisations which comprise the support systems constructed to mediate precarity in the everyday context, cultural practices and resources can play a significant role for people who are culturally connected. When people are integrated into their local and cultural communities, they can cope better with a precarious way of life.

year: 2021