title: Properties of a thermostable β-glucosidase immobilized using tris(hydroxymethyl)phosphine as a highly effective coupling agent

authors: Oswald, Paul R.

subjects: tris(hydroxymethyl)phosphine

abstract: A very stable b-glucosidase (EC 3.2.1.21) was immobilized to polyacrylamide-magnetite beads, aminopropyl silica, and chitosan using tris(hydroxymethyl)phosphine (THP) or glutaraldehyde as the coupling reagent. The use of THP on chitosan resulted in greater than 90% yields with respect to free enzyme activity compared with only 60% observed when using the more conventional glutaraldehyde coupling reagent. THP-immobilized enzyme also lost activity more slowly than both glutaraldehyde-immobilized and the free enzyme when incubated at 90°C. Repetitive assays of THP and glutaraldehyde-immobilized enzyme also showed that THP was more able to retain active enzyme on the silica-based support. The pH optimum and Km app were unchanged with respect to free enzyme.

text: Properties of a thermostable β-glucosidase immobilized using tris(hydroxymethyl)phosphine as a highly effective coupling agent A very stable b-glucosidase (EC 3.2.1.21) was immobilized to polyacrylamide-magnetite beads, aminopropyl silica, and chitosan using tris(hydroxymethyl)phosphine (THP) or glutaraldehyde as the coupling reagent. The use of THP on chitosan resulted in greater than 90% yields with respect to free enzyme activity compared with only 60% observed when using the more conventional glutaraldehyde coupling reagent. THP-immobilized enzyme also lost activity more slowly than both glutaraldehyde-immobilized and the free enzyme when incubated at 90°C. Repetitive assays of THP and glutaraldehyde-immobilized enzyme also showed that THP was more able to retain active enzyme on the silica-based support. The pH optimum and Km app were unchanged with respect to free enzyme.

year: 1998

title: Mining Arbitrarily Large Datasets Using Heuristic k-Nearest Neighbour Search

authors: Wu, Xing

subjects: computer science

abstract: Nearest Neighbour Search (NNS) is one of the top ten data mining algorithms. It is simple and effective but has a time complexity that is the product of the number of instances and the number of dimensions. When the number of dimensions is greater than two there are no known solutions that can guarantee a sublinear retrieval time. This paper describes and evaluates two ways to make NNS efficient for datasets that are arbitrarily large in the number of instances and dimensions. The methods are best described as heuristic as they are neither exact nor approximate. Both stem from recent developments in the field of data stream classification. The first uses Hoeffding Trees, an extension of decision trees to streams and the second is a direct stream extension of NNS. The methods are evaluated in terms of their accuracy and the time taken to find the neighbours. Results show that the methods are competitive with NNS in terms of accuracy but significantly faster.

text: Mining Arbitrarily Large Datasets Using Heuristic k-Nearest Neighbour Search Nearest Neighbour Search (NNS) is one of the top ten data mining algorithms. It is simple and effective but has a time complexity that is the product of the number of instances and the number of dimensions. When the number of dimensions is greater than two there are no known solutions that can guarantee a sublinear retrieval time. This paper describes and evaluates two ways to make NNS efficient for datasets that are arbitrarily large in the number of instances and dimensions. The methods are best described as heuristic as they are neither exact nor approximate. Both stem from recent developments in the field of data stream classification. The first uses Hoeffding Trees, an extension of decision trees to streams and the second is a direct stream extension of NNS. The methods are evaluated in terms of their accuracy and the time taken to find the neighbours. Results show that the methods are competitive with NNS in terms of accuracy but significantly faster.

year: 2008

title: Academic success amongst a cohort of gifted and talented Māori and Pasifika secondary school boys: Elements that have contributed to their achievement

authors: Miller, Graeme Oliver

subjects: Māori

abstract: In recent years Māori and Pasifika students have been the focus of much discussion and a significant amount of research relating to underachievement. Despite this, many Māori and Pasifika secondary school boys are achieving highly in the academic sphere within the context of mainstream boys’ state secondary schools in New Zealand. Achievement aside, evidence shows that Māori and Pasifika secondary school boys are seriously under-represented in programmes for the gifted and talented. This enquiry examines factors in relation to identifying gifted and talented students, and investigates how their abilities are forged and nurtured. The reasons for student success merit serious investigation because of how the multiple elements contributing to their achievement are likely to be applicable to others, and are a pressing concern for academic attainment in the New Zealand education system. 
 
This qualitative study examines why 30 academically successful Māori and Pasifika secondary school boys achieved highly in the mainstream education system. The boys ranged from 13 to 19 years, the youngest being in his first year at high school as a Year 9 student, and the oldest being in his second year at university. The thesis argues their academic success was due to the complex interplay of home and school environmental elements, and the boys’ intrapersonal characteristics. The study explored the boys’ and parents’ narratives to explain why students had achieved highly, and examined both the parents’ and boys’ perceptions of how well the schools had provided for their intellectual, emotional and cultural needs. Sociocultural learning theory is the main theoretical lens through which the findings are viewed. The methodology is primarily built upon narrative inquiry. The main method of data collection was by semi-structured interview, both individually and in focus groups. Supplementary methods utilised were questionnaires and observation.  
  
An issue in the research was the disparity between the cultural and ethnic background of the participants and myself as the researcher. However, an endeavour was made to mitigate this by consulting with Māori and Pasifika educators, a kaumatua (elder) and iwi (tribal) representative prior to the research commencing. In addition, models developed through this study were submitted to Māori and Pasifika educators for their comment and approval prior to being included. 
 
With its focus specifically on highly-achieving Māori and Pasifika secondary school boys, this thesis makes an original contribution to the national and international discussion about raising student achievement. It provides a platform for further research to 	address the particular concerns around the underachievement of Māori and Pasifika secondary school boys. 
 
While there are several implications arising from the research, all are linked to the need for policy makers and educators to address the issue of the underrepresentation of Māori and Pasifika students in programmes for the gifted and talented. Policies, practices and relationships need to be examined to evaluate how effectively they contribute to gifted and talented Māori and Pasifika students receiving the academic opportunities they deserve. A key part of this examination will need to include consultation with students and their whānau.

text: Academic success amongst a cohort of gifted and talented Māori and Pasifika secondary school boys: Elements that have contributed to their achievement In recent years Māori and Pasifika students have been the focus of much discussion and a significant amount of research relating to underachievement. Despite this, many Māori and Pasifika secondary school boys are achieving highly in the academic sphere within the context of mainstream boys’ state secondary schools in New Zealand. Achievement aside, evidence shows that Māori and Pasifika secondary school boys are seriously under-represented in programmes for the gifted and talented. This enquiry examines factors in relation to identifying gifted and talented students, and investigates how their abilities are forged and nurtured. The reasons for student success merit serious investigation because of how the multiple elements contributing to their achievement are likely to be applicable to others, and are a pressing concern for academic attainment in the New Zealand education system. 
 
This qualitative study examines why 30 academically successful Māori and Pasifika secondary school boys achieved highly in the mainstream education system. The boys ranged from 13 to 19 years, the youngest being in his first year at high school as a Year 9 student, and the oldest being in his second year at university. The thesis argues their academic success was due to the complex interplay of home and school environmental elements, and the boys’ intrapersonal characteristics. The study explored the boys’ and parents’ narratives to explain why students had achieved highly, and examined both the parents’ and boys’ perceptions of how well the schools had provided for their intellectual, emotional and cultural needs. Sociocultural learning theory is the main theoretical lens through which the findings are viewed. The methodology is primarily built upon narrative inquiry. The main method of data collection was by semi-structured interview, both individually and in focus groups. Supplementary methods utilised were questionnaires and observation.  
  
An issue in the research was the disparity between the cultural and ethnic background of the participants and myself as the researcher. However, an endeavour was made to mitigate this by consulting with Māori and Pasifika educators, a kaumatua (elder) and iwi (tribal) representative prior to the research commencing. In addition, models developed through this study were submitted to Māori and Pasifika educators for their comment and approval prior to being included. 
 
With its focus specifically on highly-achieving Māori and Pasifika secondary school boys, this thesis makes an original contribution to the national and international discussion about raising student achievement. It provides a platform for further research to 	address the particular concerns around the underachievement of Māori and Pasifika secondary school boys. 
 
While there are several implications arising from the research, all are linked to the need for policy makers and educators to address the issue of the underrepresentation of Māori and Pasifika students in programmes for the gifted and talented. Policies, practices and relationships need to be examined to evaluate how effectively they contribute to gifted and talented Māori and Pasifika students receiving the academic opportunities they deserve. A key part of this examination will need to include consultation with students and their whānau.

year: 2015