title: Optimizing the induction of alternating decision trees

authors: Pfahringer, Bernhard

subjects: computer science

abstract: The alternating decision tree brings comprehensibility to the performance enhancing capabilities of boosting. A single interpretable tree is induced wherein knowledge is distributed across the nodes and multiple paths are traversed to form predictions. The complexity of the algorithm is quadratic in the number of boosting iterations and this makes it unsuitable for larger knowledge discovery in database tasks. In this paper we explore various heuristic methods for reducing this complexity while maintaining the performance characteristics of the original algorithm. In experiments using standard, artificial and knowledge discovery datasets we show that a range of heuristic methods with log linear complexity are capable of achieving similar performance to the original method. Of these methods, the random walk heuristic is seen to out-perform all others as the number of boosting iterations increases. The average case complexity of this method is linear.

text: Optimizing the induction of alternating decision trees The alternating decision tree brings comprehensibility to the performance enhancing capabilities of boosting. A single interpretable tree is induced wherein knowledge is distributed across the nodes and multiple paths are traversed to form predictions. The complexity of the algorithm is quadratic in the number of boosting iterations and this makes it unsuitable for larger knowledge discovery in database tasks. In this paper we explore various heuristic methods for reducing this complexity while maintaining the performance characteristics of the original algorithm. In experiments using standard, artificial and knowledge discovery datasets we show that a range of heuristic methods with log linear complexity are capable of achieving similar performance to the original method. Of these methods, the random walk heuristic is seen to out-perform all others as the number of boosting iterations increases. The average case complexity of this method is linear.

year: 2001

title: Screening of strains identified as extremely thermophilic bacilli for extracellular proteolytic activity and general properties of the proteinases from two of the strains

authors: Coolbear, C.

subjects: L-Arginine amidinohydrolase

abstract: A thermostable arginase (l-arginine amidinohydrolase, EC 3.5.3.1) was purified from the extreme thermophile ‘Bacillus caldovelox’ (DSM 411) by a procedure including DEAE-Sepharose chromatography, and gel filtration, anion exchange and hydrophobic-interaction fast-protein liquid chromatography, with substantial retention of the metal ion cofactor. The purified enzyme is a hexamer with a subunit Mr of 31000 ± 2000 and contains ≥1 Mn atom per subunit. Maximum activation on incubation with Mn²⁺ is 29%. Activity is optimal at pH 9 and at 60°C the Km for arginine is 3.4 mM and Ki(ornithine) is 0.55 mM. Incubation in 0.1 M Mops/NaOH buffer (pH 7) causes rapid inactivation at 60°C (t1/2(half life) = 4.5 min) and individually 0.1 mM Mn²⁺ or 1 mg/ml BSA (bovine serum albumin) increase the t1/2 of arginase activity 4-fold, but combined they produce > 1000-fold increase and a t1/2 = 105 min at 95°C. Aspartic acid and other species that bind Mn²⁺ can replace BSA, and it is suggested that arginase can be activated by free Mn²⁺. A strong chelating agent causes inactivation without subunit dissociation, but arginase dissociates rapidly at pH 2.5. Reassociation occurs at pH 9 and is unusual in that it does not require Mn²⁺.

text: Screening of strains identified as extremely thermophilic bacilli for extracellular proteolytic activity and general properties of the proteinases from two of the strains A thermostable arginase (l-arginine amidinohydrolase, EC 3.5.3.1) was purified from the extreme thermophile ‘Bacillus caldovelox’ (DSM 411) by a procedure including DEAE-Sepharose chromatography, and gel filtration, anion exchange and hydrophobic-interaction fast-protein liquid chromatography, with substantial retention of the metal ion cofactor. The purified enzyme is a hexamer with a subunit Mr of 31000 ± 2000 and contains ≥1 Mn atom per subunit. Maximum activation on incubation with Mn²⁺ is 29%. Activity is optimal at pH 9 and at 60°C the Km for arginine is 3.4 mM and Ki(ornithine) is 0.55 mM. Incubation in 0.1 M Mops/NaOH buffer (pH 7) causes rapid inactivation at 60°C (t1/2(half life) = 4.5 min) and individually 0.1 mM Mn²⁺ or 1 mg/ml BSA (bovine serum albumin) increase the t1/2 of arginase activity 4-fold, but combined they produce > 1000-fold increase and a t1/2 = 105 min at 95°C. Aspartic acid and other species that bind Mn²⁺ can replace BSA, and it is suggested that arginase can be activated by free Mn²⁺. A strong chelating agent causes inactivation without subunit dissociation, but arginase dissociates rapidly at pH 2.5. Reassociation occurs at pH 9 and is unusual in that it does not require Mn²⁺.

year: 1991

title: William Nicholls, Hera Te Whakaawa, and their children

authors: Hart, Philip

abstract: Two years after arriving in New Zealand in 1840, William Nicholls married Hera Te Whakaawa, who had an illustrious whakapapa. For the rest of his life he lived as a Pakeha Maori, trading and farming on land owned by his wife. Like other Pakeha, he was excited by the discoveries of gold, and was involved in a minor way with the Coromandel and Thames goldfields and at Te Aroha, near where he was living, where he and one of his sons did some prospecting. The penultimate Pakeha Maori to die in the Te Aroha district, he was a well-respected member of the community.
Nicholls ensured that his children were well educated, and in most cases they did well in Pakeha society and made ‘good’ marriages: the daughters to Pakeha and the sons to Maori. The lives of three of his children are summarized; the others are dealt with in other papers.

text: William Nicholls, Hera Te Whakaawa, and their children Two years after arriving in New Zealand in 1840, William Nicholls married Hera Te Whakaawa, who had an illustrious whakapapa. For the rest of his life he lived as a Pakeha Maori, trading and farming on land owned by his wife. Like other Pakeha, he was excited by the discoveries of gold, and was involved in a minor way with the Coromandel and Thames goldfields and at Te Aroha, near where he was living, where he and one of his sons did some prospecting. The penultimate Pakeha Maori to die in the Te Aroha district, he was a well-respected member of the community.
Nicholls ensured that his children were well educated, and in most cases they did well in Pakeha society and made ‘good’ marriages: the daughters to Pakeha and the sons to Maori. The lives of three of his children are summarized; the others are dealt with in other papers.

year: 2016