title: Properties and stabilization of an extracellular α-glucosidase from the extremely thermophilic archaebacteria Thermococcus strain AN 1: enzyme activity at 130°C

authors: Piller, Karin

subjects: α-glucosidase

abstract: An extracellular α-glucosidase from the thermophilic archaebacterium Thermococcus strain AN1 was purified 875-fold in five steps (Hiload Q-Sepharose, phenyl Sepharose, HPHT-hydroxyapatite, gel filtration and Mono Q chromatography) with a yield of 4%. It is a monomer with a molecular mass of about 60 kDa and a pI around 5. At 98°C, the purified enzyme in buffer has a half-life around 35 min, which is increased to around 215 min in presence of l% (w/v) dithiothreitol and 1% (w/v) BSA. Dithiothreitol (1%, w/v) and BSA (0.4%, w/v) also substantially increase the enzyme activity. The Km at 75°C is 0.41 mM with pNP-α-  -glucopyranoside as substrate. The substrate preference of the enzyme is: pNP-α-D-glucoside > nigerose > panose > palatinose > isomaltose > maltose and turanose. No activity was found against starch, pullulan, amylose, maltotriose, maltotetraose, isomaltotriose, cellobiose and β-gentiobiose. A variety of techniques including immobilization (e.g., on epoxy and glass beads), chemical modification (cross- and cocross-linking) and the use of additives (including polyhydroxylic molecules, BSA, salts, etc.) were applied to enhance stability at temperatures above 100°C. The half-life could be increased from about 4 min at 110°C to 30–60 min at 130°C in presence of 90% (w/v) sorbitol, 1% (w/v) dithiothreitol and l% (w/v) BSA, and by cocross-linking with BSA in the presence of 90% (w/v) sorbitol. The stabilized enzyme showed good activity at 130°C.

text: Properties and stabilization of an extracellular α-glucosidase from the extremely thermophilic archaebacteria Thermococcus strain AN 1: enzyme activity at 130°C An extracellular α-glucosidase from the thermophilic archaebacterium Thermococcus strain AN1 was purified 875-fold in five steps (Hiload Q-Sepharose, phenyl Sepharose, HPHT-hydroxyapatite, gel filtration and Mono Q chromatography) with a yield of 4%. It is a monomer with a molecular mass of about 60 kDa and a pI around 5. At 98°C, the purified enzyme in buffer has a half-life around 35 min, which is increased to around 215 min in presence of l% (w/v) dithiothreitol and 1% (w/v) BSA. Dithiothreitol (1%, w/v) and BSA (0.4%, w/v) also substantially increase the enzyme activity. The Km at 75°C is 0.41 mM with pNP-α-  -glucopyranoside as substrate. The substrate preference of the enzyme is: pNP-α-D-glucoside > nigerose > panose > palatinose > isomaltose > maltose and turanose. No activity was found against starch, pullulan, amylose, maltotriose, maltotetraose, isomaltotriose, cellobiose and β-gentiobiose. A variety of techniques including immobilization (e.g., on epoxy and glass beads), chemical modification (cross- and cocross-linking) and the use of additives (including polyhydroxylic molecules, BSA, salts, etc.) were applied to enhance stability at temperatures above 100°C. The half-life could be increased from about 4 min at 110°C to 30–60 min at 130°C in presence of 90% (w/v) sorbitol, 1% (w/v) dithiothreitol and l% (w/v) BSA, and by cocross-linking with BSA in the presence of 90% (w/v) sorbitol. The stabilized enzyme showed good activity at 130°C.

year: 1996

title: Accelerating the XGBoost algorithm using GPU computing

authors: Mitchell, Rory

subjects: computer science

abstract: We present a CUDA-based implementation of a decision tree construction algorithm within the gradient boosting library XGBoost. The tree construction algorithm is executed entirely on the graphics processing unit (GPU) and shows high performance with a variety of datasets and settings, including sparse input matrices. Individual boosting iterations are parallelised, combining two approaches. An interleaved approach is used for shallow trees, switching to a more conventional radix sort-based approach for larger depths. We show speedups of between 3x and 6x using a Titan X compared to a 4 core i7 CPU, and 1.2x using a Titan X compared to 2x Xeon CPUs (24 cores). We show that it is possible to process the Higgs dataset (10 million instances, 28 features) entirely within GPU memory. The algorithm is made available as a plug-in within the XGBoost library and fully supports all XGBoost features including classification, regression and ranking tasks.

text: Accelerating the XGBoost algorithm using GPU computing We present a CUDA-based implementation of a decision tree construction algorithm within the gradient boosting library XGBoost. The tree construction algorithm is executed entirely on the graphics processing unit (GPU) and shows high performance with a variety of datasets and settings, including sparse input matrices. Individual boosting iterations are parallelised, combining two approaches. An interleaved approach is used for shallow trees, switching to a more conventional radix sort-based approach for larger depths. We show speedups of between 3x and 6x using a Titan X compared to a 4 core i7 CPU, and 1.2x using a Titan X compared to 2x Xeon CPUs (24 cores). We show that it is possible to process the Higgs dataset (10 million instances, 28 features) entirely within GPU memory. The algorithm is made available as a plug-in within the XGBoost library and fully supports all XGBoost features including classification, regression and ranking tasks.

year: 2017

title: Re-examining the best interests of child principle. Can this help tamariki and rangatahi Māori achieve the highest attainable standard of mental health?

authors: Karunaratne, Kalupathirannehelage Dona Thilini Prathiba

abstract: This thesis explores how a re-examination of the best interests of the child principle can assist tamariki and
rangatahi Māori to achieve the highest attainable standard of mental health. Although New Zealand has ratified the United Nations Convention on the Rights of the Child 1989, which enshrines the “best interests of the child” principle, significant disparities in mental health outcomes remain between tamariki and
rangatahi Māori and non-Māori children and young people. Drawing on international human rights law, domestic legislation, case law, and Māori concepts of health and wellbeing, this thesis develops a theoretical
and practical framework for reducing these mental health disparities. It explores whether New Zealand can utilise the best interests principle in a way that recognises and incorporates the unique cultural identity and
collective rights of tamariki and rangatahi Māori. The flexible nature of the best interests principle is leveraged to integrate collective cultural rights and Māori worldviews into mental health law and policies. By doing so, it aims to facilitate greater recognition of Māori collective rights and practices within NewZealand's legal and healthcare systems.
This research proposes that a culturally-informed interpretation of the best interests principle, aligned with Māori worldviews and values, is important for fulfilling New Zealand’s international obligations and the achievement of the highest attainable standard of mental health for tamariki and rangatahi Māori. The thesis contends that decisions concerning the best interests of tamariki and rangatahi Māori in mental health
should be guided by a “by Māori, for Māori” approach, which informs and shapes the broader application of the best interests principle. Through this analysis, the thesis seeks to contribute to the improvement of mental health outcomes for tamariki and rangatahi Māori.

text: Re-examining the best interests of child principle. Can this help tamariki and rangatahi Māori achieve the highest attainable standard of mental health? This thesis explores how a re-examination of the best interests of the child principle can assist tamariki and
rangatahi Māori to achieve the highest attainable standard of mental health. Although New Zealand has ratified the United Nations Convention on the Rights of the Child 1989, which enshrines the “best interests of the child” principle, significant disparities in mental health outcomes remain between tamariki and
rangatahi Māori and non-Māori children and young people. Drawing on international human rights law, domestic legislation, case law, and Māori concepts of health and wellbeing, this thesis develops a theoretical
and practical framework for reducing these mental health disparities. It explores whether New Zealand can utilise the best interests principle in a way that recognises and incorporates the unique cultural identity and
collective rights of tamariki and rangatahi Māori. The flexible nature of the best interests principle is leveraged to integrate collective cultural rights and Māori worldviews into mental health law and policies. By doing so, it aims to facilitate greater recognition of Māori collective rights and practices within NewZealand's legal and healthcare systems.
This research proposes that a culturally-informed interpretation of the best interests principle, aligned with Māori worldviews and values, is important for fulfilling New Zealand’s international obligations and the achievement of the highest attainable standard of mental health for tamariki and rangatahi Māori. The thesis contends that decisions concerning the best interests of tamariki and rangatahi Māori in mental health
should be guided by a “by Māori, for Māori” approach, which informs and shapes the broader application of the best interests principle. Through this analysis, the thesis seeks to contribute to the improvement of mental health outcomes for tamariki and rangatahi Māori.

year: 2026