title: Determining the probability of cyanobacterial blooms: the application of Bayesian networks in multiple lake systems

authors: Rigosi, Anna

subjects: Bayesian network

abstract: A Bayesian network model was developed to assess the combined influence of nutrient conditions and climate on the occurrence of cyanobacterial blooms within lakes of diverse hydrology and nutrient supply. Physicochemical, biological, and meteorological observations were collated from 20 lakes located at different latitudes and characterized by a range of sizes and trophic states. Using these data, we built a Bayesian network to (1) analyze the sensitivity of cyanobacterial bloom development to different environmental factors and (2) determine the probability that cyanobacterial blooms would occur. Blooms were classified in three categories of hazard (low, moderate, and high) based on cell abundances. The most important factors determining cyanobacterial bloom occurrence were water temperature, nutrient availability, and the ratio of mixing depth to euphotic depth. The probability of cyanobacterial blooms was evaluated under different combinations of total phosphorus and water temperature. The Bayesian network was then applied to quantify the probability of blooms under a future climate warming scenario. The probability of the "high hazardous" category of cyanobacterial blooms increased 5% in response to either an increase in water temperature of 0.8°C (initial water temperature above 24°C) or an increase in total phosphorus from 0.01 mg/L to 0.02 mg/L. Mesotrophic lakes were particularly vulnerable to warming. Reducing nutrient concentrations counteracts the increased cyanobacterial risk associated with higher temperatures.

text: Determining the probability of cyanobacterial blooms: the application of Bayesian networks in multiple lake systems A Bayesian network model was developed to assess the combined influence of nutrient conditions and climate on the occurrence of cyanobacterial blooms within lakes of diverse hydrology and nutrient supply. Physicochemical, biological, and meteorological observations were collated from 20 lakes located at different latitudes and characterized by a range of sizes and trophic states. Using these data, we built a Bayesian network to (1) analyze the sensitivity of cyanobacterial bloom development to different environmental factors and (2) determine the probability that cyanobacterial blooms would occur. Blooms were classified in three categories of hazard (low, moderate, and high) based on cell abundances. The most important factors determining cyanobacterial bloom occurrence were water temperature, nutrient availability, and the ratio of mixing depth to euphotic depth. The probability of cyanobacterial blooms was evaluated under different combinations of total phosphorus and water temperature. The Bayesian network was then applied to quantify the probability of blooms under a future climate warming scenario. The probability of the "high hazardous" category of cyanobacterial blooms increased 5% in response to either an increase in water temperature of 0.8°C (initial water temperature above 24°C) or an increase in total phosphorus from 0.01 mg/L to 0.02 mg/L. Mesotrophic lakes were particularly vulnerable to warming. Reducing nutrient concentrations counteracts the increased cyanobacterial risk associated with higher temperatures.

year: 2015-01-01

title: Constructions of childhood in early childhood education policy debate in New Zealand

authors: Mitchell, Linda

subjects: early childhood education

abstract: What assumptions about children and childhood are held by government officials and organisation representatives who are influential in policy formation in early childhood education (ECE) in New Zealand? How are assumptions manifested in policy? This article draws on a study carried out from 2001 to 2003, a time of radical ECE policy change in New Zealand. It uses principles derived from social constructionist theory and values expressed in the United Nations Convention on the Rights of the Child to analyse constructions of childhood in ECE policy debate during this time. Three dominant constructions about childhood were identified: a construction of the 'child as dependant within the family'; the 'child as learner within a community of learners'; and the 'child as citizen within a social community'. These constructions were associated with views about the purposes and outcomes of ECE; the roles of children, teachers, families, and government; and favoured policy approaches. It is argued that a construction of child as citizen within a social community is a new paradigm that places children's rights and agency to the forefront, and acknowledges the interdependence of care and education. As a basis for policy, it could cater better for societal change and support ECE services as participatory forums building social networks, support and cohesion.

text: Constructions of childhood in early childhood education policy debate in New Zealand What assumptions about children and childhood are held by government officials and organisation representatives who are influential in policy formation in early childhood education (ECE) in New Zealand? How are assumptions manifested in policy? This article draws on a study carried out from 2001 to 2003, a time of radical ECE policy change in New Zealand. It uses principles derived from social constructionist theory and values expressed in the United Nations Convention on the Rights of the Child to analyse constructions of childhood in ECE policy debate during this time. Three dominant constructions about childhood were identified: a construction of the 'child as dependant within the family'; the 'child as learner within a community of learners'; and the 'child as citizen within a social community'. These constructions were associated with views about the purposes and outcomes of ECE; the roles of children, teachers, families, and government; and favoured policy approaches. It is argued that a construction of child as citizen within a social community is a new paradigm that places children's rights and agency to the forefront, and acknowledges the interdependence of care and education. As a basis for policy, it could cater better for societal change and support ECE services as participatory forums building social networks, support and cohesion.

year: 2010

title: Talk More: Student Learning Through Reciprocal Conversations

authors: Grant, Sarah

subjects: oral language

abstract: This research explored ways of improving the oral language development of Year 1 children in four low decile mainstream schools who were making limited progress in literacy. Over 82% of these students were Māori.  Due to the continued impact of past educational policies and the subsequent interruption of the intergenerational transmission of the mother tongue, many Māori children are not exposed to proficient and fluent models either of spoken English or of spoken Māori.  Such children struggle to make the English literacy progress expected of them by schools and communities. The central focus of the research was to evaluate a claim that Year 6 students (tuākana)  could make a substantial improvement in the oral language achievement of  Year 1 students (teina), through engaging with them in regular conversational contexts using the TALES (Talk, Ask, Listen, Encourage, and Say) procedures. This pedagogical approach is understood as one which was culturally responsive for these students. 

Quantitative analysis of data from three quantitative outcome measures (Record of Oral Language, Junior Oral Screening Tool, and Auditory-Vocal Association Assessment of Verbal Attainments) demonstrated that there were substantial oral language gains for the 72 teina students involved in the study. The quantitative analysis also demonstrated that these gains occurred most strongly during the phases in which the TALES procedures were being implemented by the 72 tuākana students, in accord with the multiple baseline design. Detailed qualitative analysis of a random sample of six of the 72 pairs illustrated both the effectiveness of the tuākana language interaction with the teina, and the different ways that the tuākana were able to implement the TALES procedure. Analysis of five minute probes of transcripts over six weeks from these six tuākana - teina pairs indicated that a wide range of literacy activities and conversations took place. The unique learning needs and personal learning intentions of each tuakana and teina were successfully monitored using this five minute probe procedure. Powerful reciprocal learning processes were evident in transcripts of conversations between the tuākana and the teina, and also within feedback and feed-forward meetings between the tuākana and key teachers.  

The substantial oral language gains for the teina students in this study  were achieved within learning contexts that were social and  interactive, and that embodied the principles of ako (learning and teaching roles were shared) and whakawhanaungatanga (building caring and  supportive relationships). These principles are among those that underpin pedagogies that are culturally responsive (Bishop  Glynn, 1999; Glynn, Wearmouth,  Berryman, 2006; Ladson-Billings, 1995, 2006) and transformative. The results of this research study give a clear message to mainstream non-Māori teachers, that they can make a positive and substantial difference to the learning outcomes of their Māori students.

text: Talk More: Student Learning Through Reciprocal Conversations This research explored ways of improving the oral language development of Year 1 children in four low decile mainstream schools who were making limited progress in literacy. Over 82% of these students were Māori.  Due to the continued impact of past educational policies and the subsequent interruption of the intergenerational transmission of the mother tongue, many Māori children are not exposed to proficient and fluent models either of spoken English or of spoken Māori.  Such children struggle to make the English literacy progress expected of them by schools and communities. The central focus of the research was to evaluate a claim that Year 6 students (tuākana)  could make a substantial improvement in the oral language achievement of  Year 1 students (teina), through engaging with them in regular conversational contexts using the TALES (Talk, Ask, Listen, Encourage, and Say) procedures. This pedagogical approach is understood as one which was culturally responsive for these students. 

Quantitative analysis of data from three quantitative outcome measures (Record of Oral Language, Junior Oral Screening Tool, and Auditory-Vocal Association Assessment of Verbal Attainments) demonstrated that there were substantial oral language gains for the 72 teina students involved in the study. The quantitative analysis also demonstrated that these gains occurred most strongly during the phases in which the TALES procedures were being implemented by the 72 tuākana students, in accord with the multiple baseline design. Detailed qualitative analysis of a random sample of six of the 72 pairs illustrated both the effectiveness of the tuākana language interaction with the teina, and the different ways that the tuākana were able to implement the TALES procedure. Analysis of five minute probes of transcripts over six weeks from these six tuākana - teina pairs indicated that a wide range of literacy activities and conversations took place. The unique learning needs and personal learning intentions of each tuakana and teina were successfully monitored using this five minute probe procedure. Powerful reciprocal learning processes were evident in transcripts of conversations between the tuākana and the teina, and also within feedback and feed-forward meetings between the tuākana and key teachers.  

The substantial oral language gains for the teina students in this study  were achieved within learning contexts that were social and  interactive, and that embodied the principles of ako (learning and teaching roles were shared) and whakawhanaungatanga (building caring and  supportive relationships). These principles are among those that underpin pedagogies that are culturally responsive (Bishop  Glynn, 1999; Glynn, Wearmouth,  Berryman, 2006; Ladson-Billings, 1995, 2006) and transformative. The results of this research study give a clear message to mainstream non-Māori teachers, that they can make a positive and substantial difference to the learning outcomes of their Māori students.

year: 2009