title: Stress- testing Hoeffding trees

authors: Holmes, Geoffrey

subjects: computer science

abstract: Hoeffding trees are state-of-the-art in classification for data streams. They perform prediction by choosing the majority class at each leaf. Their predictive accuracy can be increased by adding Naive Bayes models at the leaves of the trees. By stress-testing these two prediction methods using noise and more complex concepts and an order of magnitude more instances than in previous studies, we discover situations where the Naive Bayes method outperforms the standard Hoeffding tree initially but is eventually overtaken. The reason for this crossover is determined and a hybrid adaptive method is proposed that generally outperforms the two original prediction methods for both simple and complex concepts as well as under noise.

text: Stress- testing Hoeffding trees Hoeffding trees are state-of-the-art in classification for data streams. They perform prediction by choosing the majority class at each leaf. Their predictive accuracy can be increased by adding Naive Bayes models at the leaves of the trees. By stress-testing these two prediction methods using noise and more complex concepts and an order of magnitude more instances than in previous studies, we discover situations where the Naive Bayes method outperforms the standard Hoeffding tree initially but is eventually overtaken. The reason for this crossover is determined and a hybrid adaptive method is proposed that generally outperforms the two original prediction methods for both simple and complex concepts as well as under noise.

year: 2005

title: Synthesis and biological activity of platinum(II) and palladium(II) thiosalicylate complexes with mixed ancillary donor ligands

authors: Henderson, William

subjects: Chemistry

abstract: A series of mixed-ligand thiosalicylate complexes of the type [ M(SC6H4CO 2)(PPh3)L] (M = Pt, L = pyridine (py), 4-methylpyridine, imidazole, 4-picolinic acid hydrazide {C5H4N[C(O)NHNH2]-4}; M = Pd, L = pyridine) have been prepared by the one-pot reaction of [PtCl2(cod)] or [PdCl2(cod)] (cod = cycloocta-1,5-diene) with one equivalent of PPh3 and thiosalicylic acid (HSC6H4CO2H) in the presence of the nitrogen base. Single-crystal X-ray diffraction studies on [P t(SC6H4CO 2)(PPh3)(py)] and the previously reported complex [P t(SC6H4CO 2)(PPh3)(XyNC)] (Xy = 2,6-xylyl) indicates that the complexes have different geometries, though in each case the two ligands of highest trans-influence are mutually cis. The reaction of [PtCl2(cod)] with PPh3, thiosalicylic acid and ammonia led to the isolation of crystals of the dinuclear thiosalicylate-bridged complex [P t(SC6H4CO 2)(PPh3)(NH3)P t(SC6H4CO 2)(PPh3)], which was characterised by X-ray crystallography and electrospray mass spectrometry. The conformation of the thiosalicylate ligand can vary widely with values for the dihedral angle between the ligand plane and the platinum(II) coordination plane varying from 12.4° to 70.9° in the seven complexes so far determined. The biological activities of selected platinum and palladium thiosalicylate and related complexes against P388 leukemia cells, bacteria and fungi are also reported. The complex [P t(SCH2CO 2)(PPh3)2] shows the highest activity against P388 cells (IC50 671 ng mL-1).

text: Synthesis and biological activity of platinum(II) and palladium(II) thiosalicylate complexes with mixed ancillary donor ligands A series of mixed-ligand thiosalicylate complexes of the type [ M(SC6H4CO 2)(PPh3)L] (M = Pt, L = pyridine (py), 4-methylpyridine, imidazole, 4-picolinic acid hydrazide {C5H4N[C(O)NHNH2]-4}; M = Pd, L = pyridine) have been prepared by the one-pot reaction of [PtCl2(cod)] or [PdCl2(cod)] (cod = cycloocta-1,5-diene) with one equivalent of PPh3 and thiosalicylic acid (HSC6H4CO2H) in the presence of the nitrogen base. Single-crystal X-ray diffraction studies on [P t(SC6H4CO 2)(PPh3)(py)] and the previously reported complex [P t(SC6H4CO 2)(PPh3)(XyNC)] (Xy = 2,6-xylyl) indicates that the complexes have different geometries, though in each case the two ligands of highest trans-influence are mutually cis. The reaction of [PtCl2(cod)] with PPh3, thiosalicylic acid and ammonia led to the isolation of crystals of the dinuclear thiosalicylate-bridged complex [P t(SC6H4CO 2)(PPh3)(NH3)P t(SC6H4CO 2)(PPh3)], which was characterised by X-ray crystallography and electrospray mass spectrometry. The conformation of the thiosalicylate ligand can vary widely with values for the dihedral angle between the ligand plane and the platinum(II) coordination plane varying from 12.4° to 70.9° in the seven complexes so far determined. The biological activities of selected platinum and palladium thiosalicylate and related complexes against P388 leukemia cells, bacteria and fungi are also reported. The complex [P t(SCH2CO 2)(PPh3)2] shows the highest activity against P388 cells (IC50 671 ng mL-1).

year: 2000-01-01

title: Estimated catchment loads of nitrogen and phosphorus to the Rotorua Te Arawa Lakes

authors: McBride, Chris G.

abstract: The Rotorua Te Arawa Lakes are central to the identity of their region, of immense historical and cultural importance, and provide ecosystem services that underpin biodiversity, conservation and socioeconomic aspirations of the community. The diversity of water quality in the lakes reflects their catchments, which are diverse in topography, hydrogeology and intensity of land use, ranging from the largely undeveloped land around lakes Tikitapu and Okataina, to highly developed forestry and pastoral land around lakes Rerewhakaaitu, Rotorua and Okaro. Lake water quality is strongly linked to nutrients received by each lake from surface flows and groundwater springs. It therefore follows that management of lake water quality requires a good understanding of nutrient loads derived from the landscape, as does the assessment or prediction of the in-lake effects of catchment-based management initiatives aimed at improving lake water quality.

text: Estimated catchment loads of nitrogen and phosphorus to the Rotorua Te Arawa Lakes The Rotorua Te Arawa Lakes are central to the identity of their region, of immense historical and cultural importance, and provide ecosystem services that underpin biodiversity, conservation and socioeconomic aspirations of the community. The diversity of water quality in the lakes reflects their catchments, which are diverse in topography, hydrogeology and intensity of land use, ranging from the largely undeveloped land around lakes Tikitapu and Okataina, to highly developed forestry and pastoral land around lakes Rerewhakaaitu, Rotorua and Okaro. Lake water quality is strongly linked to nutrients received by each lake from surface flows and groundwater springs. It therefore follows that management of lake water quality requires a good understanding of nutrient loads derived from the landscape, as does the assessment or prediction of the in-lake effects of catchment-based management initiatives aimed at improving lake water quality.

year: 2021