title: Cellulolytic properties of an extremely thermophilic anaerobe

authors: Hudson, J. Andrew

subjects: biology

abstract: An extremely thermophilic anaerobe was isolated from a New Zealand hot spring by incubating bacterial mat strands in a medium containing xylan. The Gramreaction-negative organism that was subsequently purified had a temperature optimum of 70° C and a pH optimum of 7.0. The isolate, designated strain H173, grew on a restricted range of carbon sources. In batch culture H173 could degrade Avicel completely when supplied at 5 or 10 g l⁻¹. There was an initial growth phase, during which a cellulase complex was produced and carbohydrates fermented to form acetic and lactic acids, followed by a phase where cells were not metabolising but the cellulase complex actively converted cellulose to glucose. When co-cultured with strain Rt8.B1, an ethanologenic extreme thermophile, glucose was fermented to ethanol and acetate, and no reducing sugars accumulated in the medium. In pH controlled batch culture H173 produced an increased amount of lactate and acetate but there was again a phase when reducing sugars accumulated in the medium, and these were converted to ethanol by co-culture with Rt8.B1.

text: Cellulolytic properties of an extremely thermophilic anaerobe An extremely thermophilic anaerobe was isolated from a New Zealand hot spring by incubating bacterial mat strands in a medium containing xylan. The Gramreaction-negative organism that was subsequently purified had a temperature optimum of 70° C and a pH optimum of 7.0. The isolate, designated strain H173, grew on a restricted range of carbon sources. In batch culture H173 could degrade Avicel completely when supplied at 5 or 10 g l⁻¹. There was an initial growth phase, during which a cellulase complex was produced and carbohydrates fermented to form acetic and lactic acids, followed by a phase where cells were not metabolising but the cellulase complex actively converted cellulose to glucose. When co-cultured with strain Rt8.B1, an ethanologenic extreme thermophile, glucose was fermented to ethanol and acetate, and no reducing sugars accumulated in the medium. In pH controlled batch culture H173 produced an increased amount of lactate and acetate but there was again a phase when reducing sugars accumulated in the medium, and these were converted to ethanol by co-culture with Rt8.B1.

year: 1990

title: A survey on feature drift adaptation: Definition, benchmark, challenges and future directions

authors: Barddal, Jean Paul

subjects: Science & Technology

abstract: Data stream mining is a fast growing research topic due to the ubiquity of data in several real-world problems. Given their ephemeral nature, data stream sources are expected to undergo changes in data distribution, a phenomenon called concept drift. This paper focuses on one specific type of drift that has not yet been thoroughly studied, namely feature drift. Feature drift occurs whenever a subset of features becomes, or ceases to be, relevant to the learning task; thus, learners must detect and adapt to these changes accordingly. We survey existing work on feature drift adaptation with both explicit and implicit approaches. Additionally, we benchmark several algorithms and a naive feature drift detection approach using synthetic and real-world datasets. The results from our experiments indicate the need for future research in this area as even naive approaches produced gains in accuracy while reducing resources usage. Finally, we state current research topics, challenges and future directions for feature drift adaptation.

text: A survey on feature drift adaptation: Definition, benchmark, challenges and future directions Data stream mining is a fast growing research topic due to the ubiquity of data in several real-world problems. Given their ephemeral nature, data stream sources are expected to undergo changes in data distribution, a phenomenon called concept drift. This paper focuses on one specific type of drift that has not yet been thoroughly studied, namely feature drift. Feature drift occurs whenever a subset of features becomes, or ceases to be, relevant to the learning task; thus, learners must detect and adapt to these changes accordingly. We survey existing work on feature drift adaptation with both explicit and implicit approaches. Additionally, we benchmark several algorithms and a naive feature drift detection approach using synthetic and real-world datasets. The results from our experiments indicate the need for future research in this area as even naive approaches produced gains in accuracy while reducing resources usage. Finally, we state current research topics, challenges and future directions for feature drift adaptation.

year: 2017

title: Political critique and genealogical vision in te oriori a Rihi Puhiwahine, 1870s

authors: Iti Prendergast, Sam

abstract: Long before twentieth-century scholars developed the language to describe 'settler colonialism', nineteenth-century Māori writers, composers, and storytellers critiqued British imperialism and theorized colonial violence. In mōteatea, letters, and kōrero heke iho (narratives passed down), tūpuna Māori asked what British colonial settlement would mean for te ao Māori, the Māori world. As they reflected on the changes wrought by imperialism, tūpuna offered guidance for future uri (descendants). This is an article about the ways that one wahine Māori critiqued colonization and imagined Māori futures in the context of mid-nineteenth-century colonial invasion. More specifically, it is an article about how Rihi Puhiwahine, a renowned composer, guided her descendants through a world disfigured by British imperialism.

text: Political critique and genealogical vision in te oriori a Rihi Puhiwahine, 1870s Long before twentieth-century scholars developed the language to describe 'settler colonialism', nineteenth-century Māori writers, composers, and storytellers critiqued British imperialism and theorized colonial violence. In mōteatea, letters, and kōrero heke iho (narratives passed down), tūpuna Māori asked what British colonial settlement would mean for te ao Māori, the Māori world. As they reflected on the changes wrought by imperialism, tūpuna offered guidance for future uri (descendants). This is an article about the ways that one wahine Māori critiqued colonization and imagined Māori futures in the context of mid-nineteenth-century colonial invasion. More specifically, it is an article about how Rihi Puhiwahine, a renowned composer, guided her descendants through a world disfigured by British imperialism.

year: 2024