title: Analysis of binning of normals for spherical harmonic cross-correlation

authors: Larkins, Robert L.

subjects: spherical harmonics

abstract: Spherical harmonic cross-correlation is a robust registration technique that uses the normals of two overlapping point clouds to bring them into coarse rotational alignment. This registration technique however has a high computational cost as spherical harmonics need to be calculated for every normal. By binning the normals, the computational efficiency is improved as the spherical harmonics can be pre-computed and cached at each bin location. In this paper we evaluate the efficiency and accuracy of the equiangle grid, icosahedron subdivision and the Fibonacci spiral, an approach we propose. It is found that the equiangle grid has the best efficiency as it can perform direct binning, followed by the Fibonacci spiral and then the icosahedron, all of which decrease the computational cost compared to no binning. The Fibonacci spiral produces the highest achieved accuracy of the three approaches while maintaining a low number of bins. The number of bins allowed by the equiangle grid and icosahedron are much more restrictive than the Fibonacci spiral. The performed analysis shows that the Fibonacci spiral can perform as well as the original cross-correlation algorithm without binning, while also providing a significant improvement in computational efficiency.

text: Analysis of binning of normals for spherical harmonic cross-correlation Spherical harmonic cross-correlation is a robust registration technique that uses the normals of two overlapping point clouds to bring them into coarse rotational alignment. This registration technique however has a high computational cost as spherical harmonics need to be calculated for every normal. By binning the normals, the computational efficiency is improved as the spherical harmonics can be pre-computed and cached at each bin location. In this paper we evaluate the efficiency and accuracy of the equiangle grid, icosahedron subdivision and the Fibonacci spiral, an approach we propose. It is found that the equiangle grid has the best efficiency as it can perform direct binning, followed by the Fibonacci spiral and then the icosahedron, all of which decrease the computational cost compared to no binning. The Fibonacci spiral produces the highest achieved accuracy of the three approaches while maintaining a low number of bins. The number of bins allowed by the equiangle grid and icosahedron are much more restrictive than the Fibonacci spiral. The performed analysis shows that the Fibonacci spiral can perform as well as the original cross-correlation algorithm without binning, while also providing a significant improvement in computational efficiency.

year: 2012

title: Evaluation of lactic acid bacterium from chilli waste as a potential antifungal agent for wood products

authors: O'Callahan, Diahanna Rachelle

subjects: 16S rRNA gene sequencing

abstract: Aims:  The aim of this study was to isolate lactic acid bacteria from chilli waste and evaluate metabolites produced for the ability to arrest wood decay.

Methods and Results:  Using an optical density screening method, one bacterium (isolate C11) was identified as having pronounced antifungal properties against Oligoporus placenta. This isolate was identified as Lactobacillus brevis by 16S rRNA gene sequencing. To determine antifungal activity in wood, Pinus radiata blocks were impregnated with Lact. brevis [C11] cell-free supernatant and exposed to brown rot fungi O. placenta, Antrodia xantha and Coniophora puteana. The treated timber demonstrated resistance to degradation from all fungi. The antifungal metabolites were heat stable and not affected by proteinase K, but were affected by neutralization with NaOH suggesting the metabolites were of an acidic nature. The presence of lactic and acetic acid was confirmed by HPLC analysis.

Conclusions: Lactobacillus brevis [C11] produced acidic metabolites that were able to inhibit the growth of wood decay fungi and subsequent wood decay.

Significance and Impact of the Study:  Traditional wood treatments are becoming an environmental issue as the public demands more benign options. The use of lactic acid bacteria which are considered safe for general use is a potential alternative to the conventional heavy metal chemicals currently in use.

text: Evaluation of lactic acid bacterium from chilli waste as a potential antifungal agent for wood products Aims:  The aim of this study was to isolate lactic acid bacteria from chilli waste and evaluate metabolites produced for the ability to arrest wood decay.

Methods and Results:  Using an optical density screening method, one bacterium (isolate C11) was identified as having pronounced antifungal properties against Oligoporus placenta. This isolate was identified as Lactobacillus brevis by 16S rRNA gene sequencing. To determine antifungal activity in wood, Pinus radiata blocks were impregnated with Lact. brevis [C11] cell-free supernatant and exposed to brown rot fungi O. placenta, Antrodia xantha and Coniophora puteana. The treated timber demonstrated resistance to degradation from all fungi. The antifungal metabolites were heat stable and not affected by proteinase K, but were affected by neutralization with NaOH suggesting the metabolites were of an acidic nature. The presence of lactic and acetic acid was confirmed by HPLC analysis.

Conclusions: Lactobacillus brevis [C11] produced acidic metabolites that were able to inhibit the growth of wood decay fungi and subsequent wood decay.

Significance and Impact of the Study:  Traditional wood treatments are becoming an environmental issue as the public demands more benign options. The use of lactic acid bacteria which are considered safe for general use is a potential alternative to the conventional heavy metal chemicals currently in use.

year: 2011

title: ‘He reka te wai o te hua pango: The darker the berry the sweeter the juice.' The experiences of Māori women in educational leadership in mainstream secondary schools.

authors: Taukamo, Trudy

subjects: New Zealand leadership

abstract: Although there has been a growing interest in Māori women in educational leadership, the research base in New Zealand is still limited. This study provides insights into the challenges and experiences of four Māori women who occupy a formal leadership position in a mainstream secondary school. It used a qualitative kaupapa Māori research framework. Data were collected using semi-structured one-on-one interview with open-ended questions. The four women were selected from Māori women who currently hold a formal leadership position at a senior management level in a mainstream secondary school and who identify as Māori. The reason for the purposive sample was the critical under-representation of Māori women in formal educational leadership roles. This study revealed three important aspects. Firstly, a person’s upbringing and background has a significant impact on the principles and values which underpin leadership. Secondly, it was evident that a support system whether personal or professional was crucial in a leadership position. Finally, the influences of opportunities and appointments to leadership were important in educational leadership. Clearly, the findings point to a need for a stronger mentoring programme and effective networking of Māori women. Tertiary studies and leadership programs can aid the career pathways for aspiring leaders. However, what is clear is the need for more research specific to the New Zealand context and Māori women.

text: ‘He reka te wai o te hua pango: The darker the berry the sweeter the juice.' The experiences of Māori women in educational leadership in mainstream secondary schools. Although there has been a growing interest in Māori women in educational leadership, the research base in New Zealand is still limited. This study provides insights into the challenges and experiences of four Māori women who occupy a formal leadership position in a mainstream secondary school. It used a qualitative kaupapa Māori research framework. Data were collected using semi-structured one-on-one interview with open-ended questions. The four women were selected from Māori women who currently hold a formal leadership position at a senior management level in a mainstream secondary school and who identify as Māori. The reason for the purposive sample was the critical under-representation of Māori women in formal educational leadership roles. This study revealed three important aspects. Firstly, a person’s upbringing and background has a significant impact on the principles and values which underpin leadership. Secondly, it was evident that a support system whether personal or professional was crucial in a leadership position. Finally, the influences of opportunities and appointments to leadership were important in educational leadership. Clearly, the findings point to a need for a stronger mentoring programme and effective networking of Māori women. Tertiary studies and leadership programs can aid the career pathways for aspiring leaders. However, what is clear is the need for more research specific to the New Zealand context and Māori women.

year: 2011