title: The preservation of last-glacial (>50 to 40 ka) colluvium on low-relief surfaces in Alishan, an actively uplifting mountain in southwestern Taiwan

authors: Hsieh, Meng-Long

subjects: low-relief surface

abstract: Geomorphic studies on the Taiwan orogen have long focused on the rapid erosion and efficient sediment transport in response to active tectonic uplift and frequent earthquakes/heavy rains. Little attention has been paid to the common low-relief surfaces in high mountains that appear to have been geomorphically stable for a long period of time. We undertook a study on a group of such gentle surfaces in Alishan, which consist of poorly drained hummocky slopes averaging 15° and as wide as 2 km. These gentle slopes are underlain by mass-wasting gravels 60–100 m thick, from which 22 radiocarbon dates >50 to 40 ka BP in age were obtained. Below these thick colluvial deposits are ~20° bedrock bedding planes apparently exposed by dip-slope failures. Combining these data reveals alternating hillslope erosion and deposition, along with episodic river downcutting, at a time scale of several 10⁴ yr. We relate this temporal change in geomorphic processes to glacial-interglacial climate change. During the wet inter-/post-glacial periods characterized by frequent heavy rains, landslides/debris flows prevailed and rivers were capable of conveying most sediment eroded from hillslopes. Frequent debris flows combined with sufficient bedload sediments serving as tools for fluvial erosion caused rapid river downcutting. In contrast, the low river erosion/transport capacity during the dry last-glacial period allowed progressive deposition of thick colluvium on the preexisting, gentle bedding surfaces probably eroded during the last interglacial period. This study shows how glacial-interglacial climate change influenced the river/hillslope processes and landscape evolution of the Taiwan orogen.

text: The preservation of last-glacial (>50 to 40 ka) colluvium on low-relief surfaces in Alishan, an actively uplifting mountain in southwestern Taiwan Geomorphic studies on the Taiwan orogen have long focused on the rapid erosion and efficient sediment transport in response to active tectonic uplift and frequent earthquakes/heavy rains. Little attention has been paid to the common low-relief surfaces in high mountains that appear to have been geomorphically stable for a long period of time. We undertook a study on a group of such gentle surfaces in Alishan, which consist of poorly drained hummocky slopes averaging 15° and as wide as 2 km. These gentle slopes are underlain by mass-wasting gravels 60–100 m thick, from which 22 radiocarbon dates >50 to 40 ka BP in age were obtained. Below these thick colluvial deposits are ~20° bedrock bedding planes apparently exposed by dip-slope failures. Combining these data reveals alternating hillslope erosion and deposition, along with episodic river downcutting, at a time scale of several 10⁴ yr. We relate this temporal change in geomorphic processes to glacial-interglacial climate change. During the wet inter-/post-glacial periods characterized by frequent heavy rains, landslides/debris flows prevailed and rivers were capable of conveying most sediment eroded from hillslopes. Frequent debris flows combined with sufficient bedload sediments serving as tools for fluvial erosion caused rapid river downcutting. In contrast, the low river erosion/transport capacity during the dry last-glacial period allowed progressive deposition of thick colluvium on the preexisting, gentle bedding surfaces probably eroded during the last interglacial period. This study shows how glacial-interglacial climate change influenced the river/hillslope processes and landscape evolution of the Taiwan orogen.

year: 2018

title: Generating accurate rule sets without global optimization

authors: Frank, Eibe

subjects: computer science

abstract: The two dominant schemes for rule-learning, C4.5 and RIPPER, both operate in two stages. First they induce an initial rule set and then they refine it using a rather complex optimization stage that discards (C4.5) or adjusts (RIPPER) individual rules to make them work better together. In contrast, this paper shows how good rule sets can be learned one rule at a time, without any need for global optimization. We present an algorithm for inferring rules by repeatedly generating partial decision trees, thus combining the two major paradigms for rule generation-creating rules from decision trees and the separate-and-conquer rule-learning technique. The algorithm is straightforward and elegant: despite this, experiments on standard datasets show that it produces rule sets that are as accurate as and of similar size to those generated by C4.5, and more accurate than RIPPER’s. Moreover, it operates efficiently, and because it avoids postprocessing, does not suffer the extremely slow performance on pathological example sets for which the C4.5 method has been criticized.

text: Generating accurate rule sets without global optimization The two dominant schemes for rule-learning, C4.5 and RIPPER, both operate in two stages. First they induce an initial rule set and then they refine it using a rather complex optimization stage that discards (C4.5) or adjusts (RIPPER) individual rules to make them work better together. In contrast, this paper shows how good rule sets can be learned one rule at a time, without any need for global optimization. We present an algorithm for inferring rules by repeatedly generating partial decision trees, thus combining the two major paradigms for rule generation-creating rules from decision trees and the separate-and-conquer rule-learning technique. The algorithm is straightforward and elegant: despite this, experiments on standard datasets show that it produces rule sets that are as accurate as and of similar size to those generated by C4.5, and more accurate than RIPPER’s. Moreover, it operates efficiently, and because it avoids postprocessing, does not suffer the extremely slow performance on pathological example sets for which the C4.5 method has been criticized.

year: 1998-01

title: Māori men: An indigenous psychological perspective on the interconnected self

authors: Rua, Mohi

subjects: Māori men

abstract: The positive relational practices of Māori men are seldom explored in academic research. Responding to this gap in the literature, this article explores how Māori men negotiate a positive sense of self and relationships. This research is guided by kaupapa Māori research practice, Māori cultural concepts, and relational understandings of identity and wellbeing. Our ethnographic approach involved direct observations, engagement in shared cultural practices and narrative interviews. During these interactions, participating men invoked a positive sense of self through accounts of belonging, reciprocity, dialogue, intimacy, and care for themselves, their whānau, and traditions. We found that Māori men's identities are negotiated through interactions with whānau (immediate and extended family), and particular places and practices. Our participants demonstrated how Māori men’s positive self-constructions are fundamentally interconnected with other people, cultural traditions, socio-cultural practices, physical and symbolic places, as well as their own health and the health of those around them.

text: Māori men: An indigenous psychological perspective on the interconnected self The positive relational practices of Māori men are seldom explored in academic research. Responding to this gap in the literature, this article explores how Māori men negotiate a positive sense of self and relationships. This research is guided by kaupapa Māori research practice, Māori cultural concepts, and relational understandings of identity and wellbeing. Our ethnographic approach involved direct observations, engagement in shared cultural practices and narrative interviews. During these interactions, participating men invoked a positive sense of self through accounts of belonging, reciprocity, dialogue, intimacy, and care for themselves, their whānau, and traditions. We found that Māori men's identities are negotiated through interactions with whānau (immediate and extended family), and particular places and practices. Our participants demonstrated how Māori men’s positive self-constructions are fundamentally interconnected with other people, cultural traditions, socio-cultural practices, physical and symbolic places, as well as their own health and the health of those around them.

year: 2017