title: The role of intratidal oscillations in sediment resuspension in a diurnal, partially mixed estuary

authors: O’Callaghan, J.M.

subjects: diurnal tides

abstract: Using detailed observations of the mean and turbulent properties of flow, salinity and turbidity that spanned 2001/02, we examined the physical mechanisms underpinning sediment resuspension in the low-energy Swan River estuary, Western Australia. In this diurnal tidally-dominated estuary, the presence of intratidal oscillations, a tidal inequality lasting 2 to 3 hours on the flood tide, generated by interactions of the four main diurnal and semidiurnal astronomical constituents, K₁, O₁, M₂, and S₂, played a major role in modifying vertical stratification and mixing. These intratidal oscillations are controlled by phase differences between the tropic and synodic months rather than being temporally-fixed by bed friction, as occurs in semidiurnal estuaries. Intratidal oscillations are largest, at around 0.1 m, near to the Austral solstice when the lunar and solar declination are in-phase. Despite the seemingly small change in water level, shear-induced interfacial mixing caused destratification of the water column with the top-to-bottom salinity (ΔS) difference of 3.5 present early in the flood tide eroded to less than 0.3 by the end of the intratidal oscillation. High turbidity peaks, of 250 nephelometric turbidity units, coincided with these intratidal oscillations and could not be explained by bed friction since shear stress from mean flow did not exceed threshold criteria. High Reynolds stresses of ∼1 Nm⁻² did, however, exceed τcr and together with negative Reynolds fluxes indicate a net downward transport of material. Destratification of the water column induced by shear instabilities resulted in large overturns capable of moving in situ material towards the bed during intratidal oscillations and these turbidities were ∼10 times greater than those from bed-generated resuspension observed later during the flood tide.

text: The role of intratidal oscillations in sediment resuspension in a diurnal, partially mixed estuary Using detailed observations of the mean and turbulent properties of flow, salinity and turbidity that spanned 2001/02, we examined the physical mechanisms underpinning sediment resuspension in the low-energy Swan River estuary, Western Australia. In this diurnal tidally-dominated estuary, the presence of intratidal oscillations, a tidal inequality lasting 2 to 3 hours on the flood tide, generated by interactions of the four main diurnal and semidiurnal astronomical constituents, K₁, O₁, M₂, and S₂, played a major role in modifying vertical stratification and mixing. These intratidal oscillations are controlled by phase differences between the tropic and synodic months rather than being temporally-fixed by bed friction, as occurs in semidiurnal estuaries. Intratidal oscillations are largest, at around 0.1 m, near to the Austral solstice when the lunar and solar declination are in-phase. Despite the seemingly small change in water level, shear-induced interfacial mixing caused destratification of the water column with the top-to-bottom salinity (ΔS) difference of 3.5 present early in the flood tide eroded to less than 0.3 by the end of the intratidal oscillation. High turbidity peaks, of 250 nephelometric turbidity units, coincided with these intratidal oscillations and could not be explained by bed friction since shear stress from mean flow did not exceed threshold criteria. High Reynolds stresses of ∼1 Nm⁻² did, however, exceed τcr and together with negative Reynolds fluxes indicate a net downward transport of material. Destratification of the water column induced by shear instabilities resulted in large overturns capable of moving in situ material towards the bed during intratidal oscillations and these turbidities were ∼10 times greater than those from bed-generated resuspension observed later during the flood tide.

year: 2010

title: We Reddit in a Forum: The influence of Message Boards on firm stability

authors: Corbet, Shaen

abstract: The use of messaging boards to instigate coordinated manipulation of stock prices is not a novel phenomenon. However, the growing breadth and sophistication of social media, the widespread availability of technological cloaking techniques, and the ready accessibility of leveraged derivatives have all significantly contributed to the growth of the infamous Reddit forum r/wallstreetbets. Using a lexicon of terminology designed to identify explicit and implicit manipulation attempts, this research presents several novel findings. The results indicate significantly positive, pronounced, and persistent abnormal returns in the aftermath of manipulative events, with the results being robust across several testing procedures. These abnormal returns have increased significantly in line with the growth of forum users and the reach of manipulation-related comments. Significant effects on market liquidity and analyst recommendations are further identified across tests. Such continued predatory headwinds are certainly of interest to market-makers, regulators, and policymakers alike, as the irrational exuberance incited by millennial meme stocks and sarcastic GIFs is found to have played a significant role in disrupting market functionality. The desired outcome of some of these five million monthly forum users is to create enough momentum to trigger algorithmic responses to move out-of-the-money options into a profitable state. Our results present evidence that this potential threat to corporate stability is concrete.

text: We Reddit in a Forum: The influence of Message Boards on firm stability The use of messaging boards to instigate coordinated manipulation of stock prices is not a novel phenomenon. However, the growing breadth and sophistication of social media, the widespread availability of technological cloaking techniques, and the ready accessibility of leveraged derivatives have all significantly contributed to the growth of the infamous Reddit forum r/wallstreetbets. Using a lexicon of terminology designed to identify explicit and implicit manipulation attempts, this research presents several novel findings. The results indicate significantly positive, pronounced, and persistent abnormal returns in the aftermath of manipulative events, with the results being robust across several testing procedures. These abnormal returns have increased significantly in line with the growth of forum users and the reach of manipulation-related comments. Significant effects on market liquidity and analyst recommendations are further identified across tests. Such continued predatory headwinds are certainly of interest to market-makers, regulators, and policymakers alike, as the irrational exuberance incited by millennial meme stocks and sarcastic GIFs is found to have played a significant role in disrupting market functionality. The desired outcome of some of these five million monthly forum users is to create enough momentum to trigger algorithmic responses to move out-of-the-money options into a profitable state. Our results present evidence that this potential threat to corporate stability is concrete.

year: 2022

title: Aro mai aro atu: Raising Māori-medium students' academic oral language proficiency

authors: Shandley, Rosina Mary

subjects: Māori-medium

abstract: From the early 1860s, colonial governments worked systematically to eradicate the language and culture of the indigenous people of Aotearoa / New Zealand, and, by the late 1960s, the death of the Māori language was being predicted by leading linguists. Māori leaders responded in the 1980s with language regeneration initiatives that included the birth of Māori-medium education. Today, this uniquely indigenous education system is a significant site of language learning for new generations of Māori children. In Māori-medium education, children are nurtured, educated, and loved as Māori, and they are more likely to attain educational qualifications than their Māori peers who attend English-medium schools. 

The success of Māori-medium education is achieved in the face of a raft of ongoing challenges that teachers and students confront on a daily basis. Years of language marginalisation, including the disruption to intergenerational transfer, mean Māori-medium students are required to learn the curriculum through their second and less-developed language. They have limited opportunities to hear or use the Māori language outside of the school, and this places huge pressure on teachers who are often their most significant language models. The challenge is compounded by the limited education that has been made available to teachers in relation to second-language pedagogies specifically designed for Māori-medium classrooms. The resulting situation is that Māori-medium teachers are often left struggling to find ways that they can develop students’ Māori language proficiency at the same time as their curriculum achievement so that one is not sacrificed for the other. 

This study designed and trialled pedagogies to support Māori-medium students to develop their academic oral language proficiency at the same time as their curriculum achievement. It was a mixed methods study grounded in a kaupapa Māori approach, and involved three teachers and 24 students across three separate Māori-medium schools. An Anga Putanga Ako (Curriculum Outcomes Matrix) was developed to support the students to understand what they needed to learn to progress through the writing curriculum. Teachers then learnt to share explicit learning outcomes from the Anga Putanga Ako with students before lessons and to allow them time to discuss their achievement of those outcomes in pairs at the conclusion of those lessons. Linguistic scaffolds were developed to support students’ learning conversations, including the self and peer assessment of the learning outcomes, and decisions about their curriculum achievement levels and next learning steps.

The quantitative and qualitative results of the study revealed that the confluence of the self and peer assessment practices, supported by the Anga Putanga Ako and linguistic scaffolds, improved the students’ academic oral language and accelerated their reading and writing achievement significantly beyond what is usually expected in a Māori-medium classroom in 14 weeks. The study also found that, through implementing the self and peer assessment pedagogies, teachers were able to identify ways they could develop their students’ academic language and curriculum achievement simultaneously and how these approaches could be applied across the curriculum.

It was clear from the research results that pedagogies that support second-language development and curriculum learning, such as the self and peer assessment pedagogies demonstrated in this study, need to be explicitly taught with consistency across initial and in-service teacher education programmes. This development is necessary to help ensure Māori-medium students are supported with the thinking and linguistic skills needed to contribute to the creation of new knowledge, to support or challenge the current social order as they see fit, and to continue to transfer the Māori language to new generations of mokopuna.

text: Aro mai aro atu: Raising Māori-medium students' academic oral language proficiency From the early 1860s, colonial governments worked systematically to eradicate the language and culture of the indigenous people of Aotearoa / New Zealand, and, by the late 1960s, the death of the Māori language was being predicted by leading linguists. Māori leaders responded in the 1980s with language regeneration initiatives that included the birth of Māori-medium education. Today, this uniquely indigenous education system is a significant site of language learning for new generations of Māori children. In Māori-medium education, children are nurtured, educated, and loved as Māori, and they are more likely to attain educational qualifications than their Māori peers who attend English-medium schools. 

The success of Māori-medium education is achieved in the face of a raft of ongoing challenges that teachers and students confront on a daily basis. Years of language marginalisation, including the disruption to intergenerational transfer, mean Māori-medium students are required to learn the curriculum through their second and less-developed language. They have limited opportunities to hear or use the Māori language outside of the school, and this places huge pressure on teachers who are often their most significant language models. The challenge is compounded by the limited education that has been made available to teachers in relation to second-language pedagogies specifically designed for Māori-medium classrooms. The resulting situation is that Māori-medium teachers are often left struggling to find ways that they can develop students’ Māori language proficiency at the same time as their curriculum achievement so that one is not sacrificed for the other. 

This study designed and trialled pedagogies to support Māori-medium students to develop their academic oral language proficiency at the same time as their curriculum achievement. It was a mixed methods study grounded in a kaupapa Māori approach, and involved three teachers and 24 students across three separate Māori-medium schools. An Anga Putanga Ako (Curriculum Outcomes Matrix) was developed to support the students to understand what they needed to learn to progress through the writing curriculum. Teachers then learnt to share explicit learning outcomes from the Anga Putanga Ako with students before lessons and to allow them time to discuss their achievement of those outcomes in pairs at the conclusion of those lessons. Linguistic scaffolds were developed to support students’ learning conversations, including the self and peer assessment of the learning outcomes, and decisions about their curriculum achievement levels and next learning steps.

The quantitative and qualitative results of the study revealed that the confluence of the self and peer assessment practices, supported by the Anga Putanga Ako and linguistic scaffolds, improved the students’ academic oral language and accelerated their reading and writing achievement significantly beyond what is usually expected in a Māori-medium classroom in 14 weeks. The study also found that, through implementing the self and peer assessment pedagogies, teachers were able to identify ways they could develop their students’ academic language and curriculum achievement simultaneously and how these approaches could be applied across the curriculum.

It was clear from the research results that pedagogies that support second-language development and curriculum learning, such as the self and peer assessment pedagogies demonstrated in this study, need to be explicitly taught with consistency across initial and in-service teacher education programmes. This development is necessary to help ensure Māori-medium students are supported with the thinking and linguistic skills needed to contribute to the creation of new knowledge, to support or challenge the current social order as they see fit, and to continue to transfer the Māori language to new generations of mokopuna.

year: 2022