title: Observations of nonlinear run-up patterns on plane and rhythmic beach morphology

authors: Bryan, Karin R.

subjects: nonlinear

abstract: Application of non-linear forecasting and bispectral analysis to video observations of run-up over cuspate topography shows that these alongshore patterns in the morphology are accompanied by changes to the fundamental behaviour of the run-up timeseries. Nonlinear forecasting indicates that at beach cusp horns, the behaviour of swash flow is more predictable and global (meaning that characteristics of individual swash events are well represented by the behaviour of the timeseries as a whole). Conversely, at beach cusp bays, the behaviour of swash flow is less predictable and more local (meaning that the characteristics of individual swash events are best represented by the behaviour of a small fraction of the timeseries). Bispectral analysis indicates that there is a nonlinear transfer of energy from the incident wave frequency f to infragravity frequency ~f/2 which only occurs in the bay, suggesting that the local behaviour is caused by interactions between successive swash cycles which are magnified by channelling caused by the beach cusp geometry. The local behaviour and the bispectral signatures are not present in offshore measurements, and are not present in runup timeseries collected when the beach was planar. These results provide evidence that interactions between successive run-ups are a fundamental characteristic of beach cusp bays. Ultimately, these interactions could lead to the growth of an infragravity wave with an alongshore wavelength forced by the presence of beach cusps.

text: Observations of nonlinear run-up patterns on plane and rhythmic beach morphology Application of non-linear forecasting and bispectral analysis to video observations of run-up over cuspate topography shows that these alongshore patterns in the morphology are accompanied by changes to the fundamental behaviour of the run-up timeseries. Nonlinear forecasting indicates that at beach cusp horns, the behaviour of swash flow is more predictable and global (meaning that characteristics of individual swash events are well represented by the behaviour of the timeseries as a whole). Conversely, at beach cusp bays, the behaviour of swash flow is less predictable and more local (meaning that the characteristics of individual swash events are best represented by the behaviour of a small fraction of the timeseries). Bispectral analysis indicates that there is a nonlinear transfer of energy from the incident wave frequency f to infragravity frequency ~f/2 which only occurs in the bay, suggesting that the local behaviour is caused by interactions between successive swash cycles which are magnified by channelling caused by the beach cusp geometry. The local behaviour and the bispectral signatures are not present in offshore measurements, and are not present in runup timeseries collected when the beach was planar. These results provide evidence that interactions between successive run-ups are a fundamental characteristic of beach cusp bays. Ultimately, these interactions could lead to the growth of an infragravity wave with an alongshore wavelength forced by the presence of beach cusps.

year: 2010

title: Blu-ray cytometer

authors: Albugami, Naser

abstract: The flow cytometers are one of the most powerful devices used to measure the properties of individual particles passing through a sensing region. In this thesis, a low cost cytometer using a Blu-ray pickup is analysed and further developed. This includes the characterisation of the existing system and its performance as well as the evaluation of count rate for different flow rates and focuses. Based on that, the best parameters for measurement conditions have been determined. The system was set up for forward scatter as well as for fluorescence, both were to be measured at the same time and it was found that both could be recorded and counted. In addition, it was found that fluorescing particles can give a fluorescent count as well as scatter count and it was noticed that different sizes of non-fluorescent particles can produce scatter count. The count rate for a mixture of fluorescent and non-fluorescent particles was measured. This required the installation of two different amplifiers (for fluorescent and non-fluorescent particles) and building a new LabView program containing two channels.

In a later part of the thesis, the system was improved to progress towards a setup of avalanche photodiode as detector for forward scattering as well as fluorescence. This gives a very good counting accuracy of 90% at speed of 10μl/s. However, this counting accuracy drops to 80% at speed of 1μl/s when mixing fluorescent and non-fluorescent particles. The counting accuracy is the ratio (in percent) of the measured count to the actual one. As a new detection approach, a beam stop was installed in front of the photo detector so scattered laser light from particles was detected instead of a reduction of laser intensity. This part of the project proves Mie theory which states that the the forward scattered light is in the forward direction. To double check this result, a beam pass was installed in front of the photo detector and the calculated percentage of counting accuracy was very close to the one without a beam stop. It was also checked that the system was capable of detection fluorescent particle after the installation of a high bass filter which passes fluorescent wavelength signals (green) and blocks the blue ray signals. Finally, it was found that this system is able to detect small size particles, such as 1μm particles and to distinguish between 1μm and 10μm particles.

text: Blu-ray cytometer The flow cytometers are one of the most powerful devices used to measure the properties of individual particles passing through a sensing region. In this thesis, a low cost cytometer using a Blu-ray pickup is analysed and further developed. This includes the characterisation of the existing system and its performance as well as the evaluation of count rate for different flow rates and focuses. Based on that, the best parameters for measurement conditions have been determined. The system was set up for forward scatter as well as for fluorescence, both were to be measured at the same time and it was found that both could be recorded and counted. In addition, it was found that fluorescing particles can give a fluorescent count as well as scatter count and it was noticed that different sizes of non-fluorescent particles can produce scatter count. The count rate for a mixture of fluorescent and non-fluorescent particles was measured. This required the installation of two different amplifiers (for fluorescent and non-fluorescent particles) and building a new LabView program containing two channels.

In a later part of the thesis, the system was improved to progress towards a setup of avalanche photodiode as detector for forward scattering as well as fluorescence. This gives a very good counting accuracy of 90% at speed of 10μl/s. However, this counting accuracy drops to 80% at speed of 1μl/s when mixing fluorescent and non-fluorescent particles. The counting accuracy is the ratio (in percent) of the measured count to the actual one. As a new detection approach, a beam stop was installed in front of the photo detector so scattered laser light from particles was detected instead of a reduction of laser intensity. This part of the project proves Mie theory which states that the the forward scattered light is in the forward direction. To double check this result, a beam pass was installed in front of the photo detector and the calculated percentage of counting accuracy was very close to the one without a beam stop. It was also checked that the system was capable of detection fluorescent particle after the installation of a high bass filter which passes fluorescent wavelength signals (green) and blocks the blue ray signals. Finally, it was found that this system is able to detect small size particles, such as 1μm particles and to distinguish between 1μm and 10μm particles.

year: 2012

title: Addressing the context and complexity of indigenous language revitalization

authors: May, Stephen

subjects: revitilization

abstract: This response discusses six key themes that emerge, either explicitly or implicitly, from Nancy Hornberger's exemplary analysis of the challenges facing indigenous language revitalization initiatives, particularly as they are currently expressed and implemented in three key indigenous language education contexts--Quechua in the South American Andes; Guarani in Paraguay and Maori in Aotearoa/New Zealand. These themes include, first, the importance of recognizing the wider social and political contexts within which indigenous revitalization initiatives are invariably situated. Second, it requires a related recognition of the internationalism of these initiatives. Third, any academic analysis of indigenous language revitalization requires, or at least must benefit from, an interdisciplinary approach, as exemplified by Hornberger's own analysis. Fourth, Hornberger's continua of biliteracy provides a sufficiently robust framework to explore the complexities and interrelationships inevitably involved in the articulation of language revitalization efforts, as well as how individuals and groups are situated in relation to those efforts. Fifth, the ongoing challenges and tensions inherent in indigenous language revitalization efforts need to continue to be discussed candidly, in order for them to be seriously addressed and, where possible, resolved. And finally, the importance of recognizing and including the voices of those centrally involved in these initiatives, as Hornberger again does, is a crucial feature, as well as a reflection of the inclusive, emancipatory aims of indigenous language revitalization itself.

text: Addressing the context and complexity of indigenous language revitalization This response discusses six key themes that emerge, either explicitly or implicitly, from Nancy Hornberger's exemplary analysis of the challenges facing indigenous language revitalization initiatives, particularly as they are currently expressed and implemented in three key indigenous language education contexts--Quechua in the South American Andes; Guarani in Paraguay and Maori in Aotearoa/New Zealand. These themes include, first, the importance of recognizing the wider social and political contexts within which indigenous revitalization initiatives are invariably situated. Second, it requires a related recognition of the internationalism of these initiatives. Third, any academic analysis of indigenous language revitalization requires, or at least must benefit from, an interdisciplinary approach, as exemplified by Hornberger's own analysis. Fourth, Hornberger's continua of biliteracy provides a sufficiently robust framework to explore the complexities and interrelationships inevitably involved in the articulation of language revitalization efforts, as well as how individuals and groups are situated in relation to those efforts. Fifth, the ongoing challenges and tensions inherent in indigenous language revitalization efforts need to continue to be discussed candidly, in order for them to be seriously addressed and, where possible, resolved. And finally, the importance of recognizing and including the voices of those centrally involved in these initiatives, as Hornberger again does, is a crucial feature, as well as a reflection of the inclusive, emancipatory aims of indigenous language revitalization itself.

year: 2006-01-01