title: Efficient data stream classification via probabilistic adaptive windows

authors: Bifet, Albert

subjects: computer science

abstract: In the context of a data stream, a classifier must be able to learn from a theoretically-infinite stream of examples using limited time and memory, while being able to predict at any point. Many methods deal with this problem by basing their model on a window of examples. We introduce a probabilistic adaptive window (PAW) for data-stream learning, which improves this windowing technique with a mechanism to include older examples as well as the most recent ones, thus maintaining information on past concept drifts while being able to adapt quickly to new ones. We exemplify PAW with lazy learning methods in two variations: one to handle concept drift explicitly, and the other to add classifier diversity using an ensemble. Along with the standard measures of accuracy and time and memory use, we compare classifiers against state-of-the-art classifiers from the data-stream literature.

text: Efficient data stream classification via probabilistic adaptive windows In the context of a data stream, a classifier must be able to learn from a theoretically-infinite stream of examples using limited time and memory, while being able to predict at any point. Many methods deal with this problem by basing their model on a window of examples. We introduce a probabilistic adaptive window (PAW) for data-stream learning, which improves this windowing technique with a mechanism to include older examples as well as the most recent ones, thus maintaining information on past concept drifts while being able to adapt quickly to new ones. We exemplify PAW with lazy learning methods in two variations: one to handle concept drift explicitly, and the other to add classifier diversity using an ensemble. Along with the standard measures of accuracy and time and memory use, we compare classifiers against state-of-the-art classifiers from the data-stream literature.

year: 2013

title: Cleavage of Ge–S and C–H bonds in the reaction of electron-deficient [Os₃(CO)₈(μ-H)(μ₃-Ph₂PCH₂P(Ph)C₆H₄)] with Ph₃GeSPh: Generation of thiophenol derivatives [Os₃(CO)₈(μ-H)(μ-SPh)(μ-dppm)] and [Os₃(CO)₇(μ-H)(μ-SPh)(μ₃-SC₆H₄)(μ-dppm)]

authors: Raha, Arun K.

subjects: triosmium clusters

abstract: Heating the electron-deficient [Os₃(CO)₈(μ-H)(μ₃-Ph₂PCH₂P(Ph)C₆H₄)] (1) and Ph₃GeSPh in benzene at 80 °C led to the thiolato bridged compounds, [Os₃(CO)₈(μ-H)(μ-SPh)(μ-dppm)] (2) and [Os₃(CO)₇(μ-H)(μ-SPh)(μ₃-SC₆H₄)(μ-dppm)] (3), formed by cleavage of Ge–S and C–S bonds of the ligand, in 40% and 17% yields, respectively. Both compounds 2 and 3 have been characterized by a combination of elemental analysis, infrared and ¹H NMR spectroscopic data together with single crystal X-ray crystallography. Compound 3 contains an open triangle of osmium atoms bridged by a SPh and SC₆H₄ ligands on opposite sides of the cluster with a dppm ligand bridging one of the Os–Os edges. Compound 2 consists of a closed triangular cluster of osmium atoms with a bridging SPh, and a bridging hydride ligand on the same Os–Os edge, and a dppm ligand bridging one of the remaining Os–Os edges.

text: Cleavage of Ge–S and C–H bonds in the reaction of electron-deficient [Os₃(CO)₈(μ-H)(μ₃-Ph₂PCH₂P(Ph)C₆H₄)] with Ph₃GeSPh: Generation of thiophenol derivatives [Os₃(CO)₈(μ-H)(μ-SPh)(μ-dppm)] and [Os₃(CO)₇(μ-H)(μ-SPh)(μ₃-SC₆H₄)(μ-dppm)] Heating the electron-deficient [Os₃(CO)₈(μ-H)(μ₃-Ph₂PCH₂P(Ph)C₆H₄)] (1) and Ph₃GeSPh in benzene at 80 °C led to the thiolato bridged compounds, [Os₃(CO)₈(μ-H)(μ-SPh)(μ-dppm)] (2) and [Os₃(CO)₇(μ-H)(μ-SPh)(μ₃-SC₆H₄)(μ-dppm)] (3), formed by cleavage of Ge–S and C–S bonds of the ligand, in 40% and 17% yields, respectively. Both compounds 2 and 3 have been characterized by a combination of elemental analysis, infrared and ¹H NMR spectroscopic data together with single crystal X-ray crystallography. Compound 3 contains an open triangle of osmium atoms bridged by a SPh and SC₆H₄ ligands on opposite sides of the cluster with a dppm ligand bridging one of the Os–Os edges. Compound 2 consists of a closed triangular cluster of osmium atoms with a bridging SPh, and a bridging hydride ligand on the same Os–Os edge, and a dppm ligand bridging one of the remaining Os–Os edges.

year: 2008

title: The source, composition and typology of ‘Limestone’ Adzes from Eastern North Island, New Zealand

authors: Nelson, Campbell S.

subjects: adzes

abstract: Collections of stone adzes (toki) from the eastern North Island of New Zealand include a number of typologically early (Archaic) forms made from what has been previously described as ‘siliceous or silicified limestone’. Seventy five finished adzes and preforms of this material were recorded in the present study. Their geographic distribution is primarily restricted to southern Hawkes Bay – Wairarapa, and they apparently originated from a single manufacturing centre at Owahanga, on the northern Wairarapa coast. Chemical and mineralogical analyses (by X-ray fluorescence, portable XRF, vacuum gasometry and X-ray diffraction) of two artefacts from Owahanga show they contain about 20–30 per cent CaCO3 (as calcite), while samples of the presumed local source rock have a slightly higher carbonate content but comparable silica (quartz) and Rb concentrations. The rock type used in the manufacture of adzes was therefore not a true limestone but calcareous mudstone, compositionally distinct from siliceous limestones in southern Wairarapa and probably derived from the Whangai Formation. Possible reasons for the use of this stone material are discussed.

text: The source, composition and typology of ‘Limestone’ Adzes from Eastern North Island, New Zealand Collections of stone adzes (toki) from the eastern North Island of New Zealand include a number of typologically early (Archaic) forms made from what has been previously described as ‘siliceous or silicified limestone’. Seventy five finished adzes and preforms of this material were recorded in the present study. Their geographic distribution is primarily restricted to southern Hawkes Bay – Wairarapa, and they apparently originated from a single manufacturing centre at Owahanga, on the northern Wairarapa coast. Chemical and mineralogical analyses (by X-ray fluorescence, portable XRF, vacuum gasometry and X-ray diffraction) of two artefacts from Owahanga show they contain about 20–30 per cent CaCO3 (as calcite), while samples of the presumed local source rock have a slightly higher carbonate content but comparable silica (quartz) and Rb concentrations. The rock type used in the manufacture of adzes was therefore not a true limestone but calcareous mudstone, compositionally distinct from siliceous limestones in southern Wairarapa and probably derived from the Whangai Formation. Possible reasons for the use of this stone material are discussed.

year: 2016