title: Biogeography and Genetic Diversity of Terrestrial Mites in the Ross Sea Region, Antarctica

authors: Collins, Gemma E.

abstract: Free-living terrestrial mites (Acari) have persisted through numerous glacial cycles in Antarctica. Very little is known, however, of their genetic diversity and distribution, particularly within the Ross Sea region. To redress this gap, we sampled mites throughout the Ross Sea region, East Antarctica, including Victoria Land and the Queen Maud Mountains (QMM), covering a latitudinal range of 72–85 °S, as well as Lauft Island near Mt. Siple (73 °S) in West Antarctica and Macquarie Island (54oS) in the sub-Antarctic. We assessed genetic diversity using mitochondrial cytochrome c oxidase subunit I gene sequences (COI-5P DNA barcode region), and also morphologically identified voucher specimens. We obtained 130 sequences representing four genera: Nanorchestes (n = 30 sequences), Stereotydeus (n = 46), Coccorhagidia (n = 18) and Eupodes (n = 36). Tree-based analyses (maximum likelihood) revealed 13 genetic clusters, representing as many as 23 putative species indicated by barcode index numbers (BINs) from the Barcode of Life Datasystems (BOLD) database. We found evidence for geographically-isolated cryptic species, e.g., within Stereotydeus belli and S. punctatus, as well as unique genetic groups occurring in sympatry (e.g., Nanorchestes spp. in QMM). Collectively, these data confirm high genetic divergence as a consequence of geographic isolation over evolutionary timescales. From a conservation perspective, additional targeted sampling of understudied areas in the Ross Sea region should be prioritised, as further diversity is likely to be found in these short-range endemic mites.

text: Biogeography and Genetic Diversity of Terrestrial Mites in the Ross Sea Region, Antarctica Free-living terrestrial mites (Acari) have persisted through numerous glacial cycles in Antarctica. Very little is known, however, of their genetic diversity and distribution, particularly within the Ross Sea region. To redress this gap, we sampled mites throughout the Ross Sea region, East Antarctica, including Victoria Land and the Queen Maud Mountains (QMM), covering a latitudinal range of 72–85 °S, as well as Lauft Island near Mt. Siple (73 °S) in West Antarctica and Macquarie Island (54oS) in the sub-Antarctic. We assessed genetic diversity using mitochondrial cytochrome c oxidase subunit I gene sequences (COI-5P DNA barcode region), and also morphologically identified voucher specimens. We obtained 130 sequences representing four genera: Nanorchestes (n = 30 sequences), Stereotydeus (n = 46), Coccorhagidia (n = 18) and Eupodes (n = 36). Tree-based analyses (maximum likelihood) revealed 13 genetic clusters, representing as many as 23 putative species indicated by barcode index numbers (BINs) from the Barcode of Life Datasystems (BOLD) database. We found evidence for geographically-isolated cryptic species, e.g., within Stereotydeus belli and S. punctatus, as well as unique genetic groups occurring in sympatry (e.g., Nanorchestes spp. in QMM). Collectively, these data confirm high genetic divergence as a consequence of geographic isolation over evolutionary timescales. From a conservation perspective, additional targeted sampling of understudied areas in the Ross Sea region should be prioritised, as further diversity is likely to be found in these short-range endemic mites.

year: 2023

title: Scaling acoustic directional couplers using 3D printing

authors: MacDonell, Marcus Scott Glengarry

subjects: Directional coupler

abstract: Acoustic directional couplers permit separation of forward and reverse sound pressure waves. This separation opens the way to traceable, precision acoustic reflection measurements. In order to span the audio spectrum, multiple couplers will be required as each coupler only operates slightly over one octave. To reach 20 kHz or above requires very small, mechanically-precise construction. We achieve this precision using 3D printing techniques.
The Lagasse design method was used by Pennington to create a coupler that operated over a designed range of 1-2 kHz. This design was scaled to create an acoustic directional coupler with a designed range of 10-20 kHz. Because frequency scales inversely with the size of the coupler, the coupler needs to be built with a very high degree of precision. The coupler was therefore designed and modeled in SolidWorks and 3D printed to high precision. 
Characterization of the couplers was achieved using two distinct methods. The first, a preliminary measurement method to test the hypothesis and the second, a high precision automated measurement. The automation was scripted in python on a Ubuntu Linux distribution.
Future work may include an Acoustic coupler to be used in ultrasound, to do this the coupler would need to be scaled a further 2.5 times. This would likely prove difficult as the wavelengths at 50 kHz are in the order of mm, comparable with those of electromagnetic waves at 44 GHz.

text: Scaling acoustic directional couplers using 3D printing Acoustic directional couplers permit separation of forward and reverse sound pressure waves. This separation opens the way to traceable, precision acoustic reflection measurements. In order to span the audio spectrum, multiple couplers will be required as each coupler only operates slightly over one octave. To reach 20 kHz or above requires very small, mechanically-precise construction. We achieve this precision using 3D printing techniques.
The Lagasse design method was used by Pennington to create a coupler that operated over a designed range of 1-2 kHz. This design was scaled to create an acoustic directional coupler with a designed range of 10-20 kHz. Because frequency scales inversely with the size of the coupler, the coupler needs to be built with a very high degree of precision. The coupler was therefore designed and modeled in SolidWorks and 3D printed to high precision. 
Characterization of the couplers was achieved using two distinct methods. The first, a preliminary measurement method to test the hypothesis and the second, a high precision automated measurement. The automation was scripted in python on a Ubuntu Linux distribution.
Future work may include an Acoustic coupler to be used in ultrasound, to do this the coupler would need to be scaled a further 2.5 times. This would likely prove difficult as the wavelengths at 50 kHz are in the order of mm, comparable with those of electromagnetic waves at 44 GHz.

year: 2015

title: Bucking the Trends: Increasing retention rates of Māori students enrolled in Faculty of Arts and Social Sciences courses at the University of Waikato

authors: Levy, Michelle Patricia

subjects: Maori

abstract: Reports on the success of the Faculty of Arts and Social Sciences at the University of Waikato’s monitoring and support for Maori students initiative. The aim of the initative was to implement a support system in the FASS that would enhance retention rates for
Māori students in the Faculty.

text: Bucking the Trends: Increasing retention rates of Māori students enrolled in Faculty of Arts and Social Sciences courses at the University of Waikato Reports on the success of the Faculty of Arts and Social Sciences at the University of Waikato’s monitoring and support for Maori students initiative. The aim of the initative was to implement a support system in the FASS that would enhance retention rates for
Māori students in the Faculty.

year: 2003