title: Rock art and frontier conflict in Southeast Asia: Insights from direct radiocarbon ages for the large human figures of Gua Sireh, Sarawak

authors: Huntley, J

abstract: Gua Sireh, located in western Sarawak (Malaysian Borneo), is known for its rock art. The cave houses hundreds of charcoal drawings depicting people, often with headdresses, knives and other accoutrements. Here, we present direct radiocarbon dates and pigment characterizations from charcoal drawings of two large (>75 cm), unique Gua Sireh human figures (anthropomorphs). To our knowledge, these are the first chronometric ages generated for Malaysian rock art, providing insights into the social contexts of art production, as well as the opportunities and challenges of dating rock art associated with the Malay/Austronesian diasporas in Southeast Asia more generally. Previous archaeological excavations revealed that people occupied Gua Sireh from around 20,000 years ago to as recently as AD 1900. The site is within Bidayuh territory, and these local Indigenous peoples recall the cave's use as a refuge during territorial violence in the early 1800s. The age of the drawings, dated between 280 and 120 cal BP (AD 1670 to 1830), corresponds with a period of increasing conflict when the Malay elites controlling the region exacted heavy tolls on the local hill tribes. We discuss rock art production at Gua Sireh in this context of frontier conflict and Bidayuh resistance.

text: Rock art and frontier conflict in Southeast Asia: Insights from direct radiocarbon ages for the large human figures of Gua Sireh, Sarawak Gua Sireh, located in western Sarawak (Malaysian Borneo), is known for its rock art. The cave houses hundreds of charcoal drawings depicting people, often with headdresses, knives and other accoutrements. Here, we present direct radiocarbon dates and pigment characterizations from charcoal drawings of two large (>75 cm), unique Gua Sireh human figures (anthropomorphs). To our knowledge, these are the first chronometric ages generated for Malaysian rock art, providing insights into the social contexts of art production, as well as the opportunities and challenges of dating rock art associated with the Malay/Austronesian diasporas in Southeast Asia more generally. Previous archaeological excavations revealed that people occupied Gua Sireh from around 20,000 years ago to as recently as AD 1900. The site is within Bidayuh territory, and these local Indigenous peoples recall the cave's use as a refuge during territorial violence in the early 1800s. The age of the drawings, dated between 280 and 120 cal BP (AD 1670 to 1830), corresponds with a period of increasing conflict when the Malay elites controlling the region exacted heavy tolls on the local hill tribes. We discuss rock art production at Gua Sireh in this context of frontier conflict and Bidayuh resistance.

year: 2023

title: Denitrification potential in lake sediment increases across a gradient of catchment agriculture

authors: Bruesewitz, Denise A.

subjects: nitrogen

abstract: Intensification of catchment agriculture has increased nutrient loads and accelerated eutrophication in some lakes, often resulting in episodic harmful algal blooms or prolonged periods of anoxia. The influence of catchment agriculture on lake sediment denitrification capacity as a nitrogen (N) removal mechanism in lakes is largely unknown, particularly in contrast to research on denitrification in agricultural streams and rivers. We measured denitrification enzyme activity (DEA) to assess sediment denitrification potential in seven monomictic and three polymictic lakes that range in the proportion of agriculture in the catchment from 3 to 96% to determine if there is a link between agricultural land use in the lake catchment and sediment denitrification potential. We collected sediment cores for DEA measurements over 3 weeks in austral spring 2008 (October– November). Lake Okaro, with 96% catchment agriculture, had approximately 15 times higher DEA than Lake Tikitapu, with 3% catchment agriculture (232.2 ± 55.9 vs. 15.9 ± 4.5 lg N gAFDM -1 h-1, respectively). Additionally, sediment denitrification potential increased with the proportion of catchment in agriculture (R2 = 0.85, P < 0.001). Our data suggest that lakes retain a high capacity to remove excessNvia denitrification under increasing N loads from higher proportions of catchment agriculture. However, evidence from the literature suggests that despite a high capacity for denitrification and longer water residence times, lakes with high N loads will still remove a smaller proportion of their N load. Lakes have a denitrification potential that reflects the condition of the lake catchment, but more measurements of in situ denitrification rates across lake catchments is necessary to determine if this capacity translates to high N removal rates.

text: Denitrification potential in lake sediment increases across a gradient of catchment agriculture Intensification of catchment agriculture has increased nutrient loads and accelerated eutrophication in some lakes, often resulting in episodic harmful algal blooms or prolonged periods of anoxia. The influence of catchment agriculture on lake sediment denitrification capacity as a nitrogen (N) removal mechanism in lakes is largely unknown, particularly in contrast to research on denitrification in agricultural streams and rivers. We measured denitrification enzyme activity (DEA) to assess sediment denitrification potential in seven monomictic and three polymictic lakes that range in the proportion of agriculture in the catchment from 3 to 96% to determine if there is a link between agricultural land use in the lake catchment and sediment denitrification potential. We collected sediment cores for DEA measurements over 3 weeks in austral spring 2008 (October– November). Lake Okaro, with 96% catchment agriculture, had approximately 15 times higher DEA than Lake Tikitapu, with 3% catchment agriculture (232.2 ± 55.9 vs. 15.9 ± 4.5 lg N gAFDM -1 h-1, respectively). Additionally, sediment denitrification potential increased with the proportion of catchment in agriculture (R2 = 0.85, P < 0.001). Our data suggest that lakes retain a high capacity to remove excessNvia denitrification under increasing N loads from higher proportions of catchment agriculture. However, evidence from the literature suggests that despite a high capacity for denitrification and longer water residence times, lakes with high N loads will still remove a smaller proportion of their N load. Lakes have a denitrification potential that reflects the condition of the lake catchment, but more measurements of in situ denitrification rates across lake catchments is necessary to determine if this capacity translates to high N removal rates.

year: 2011

title: Testing a suicidal ideation-to-action framework among Queer and Takatāpui people in Aotearoa New Zealand: An examination of the three-step theory

authors: Schimanski, Irie

abstract: The three-step theory (3ST) of suicide is well-established in the general population and shows promise for explaining suicidal ideation among Queer samples. This study examined the applicability of the 3ST using data from 250 Queer (n = 213) and Takatāpui (n = 37) people aged 18-74 living in Aotearoa New Zealand. The analytic approach entailed hierarchical multiple regression, ANOVA, t-tests, and logistic regression. Step-one was partially supported, with discrimination and hopelessness independently associated with suicidal ideation, but not their interaction. Step-two was fully supported, showing social support associated with lower suicidal ideation when social support exceeded discrimination, compared with the inverse. Full support for step-three was observed, finding higher self-harm among participants with histories of attempted suicide than those who had never attempted. An adapted version of the 3ST for Queer and Takatāpui people is presented, offering novel approaches to testing the ideation-to-action framework with these communities.

text: Testing a suicidal ideation-to-action framework among Queer and Takatāpui people in Aotearoa New Zealand: An examination of the three-step theory The three-step theory (3ST) of suicide is well-established in the general population and shows promise for explaining suicidal ideation among Queer samples. This study examined the applicability of the 3ST using data from 250 Queer (n = 213) and Takatāpui (n = 37) people aged 18-74 living in Aotearoa New Zealand. The analytic approach entailed hierarchical multiple regression, ANOVA, t-tests, and logistic regression. Step-one was partially supported, with discrimination and hopelessness independently associated with suicidal ideation, but not their interaction. Step-two was fully supported, showing social support associated with lower suicidal ideation when social support exceeded discrimination, compared with the inverse. Full support for step-three was observed, finding higher self-harm among participants with histories of attempted suicide than those who had never attempted. An adapted version of the 3ST for Queer and Takatāpui people is presented, offering novel approaches to testing the ideation-to-action framework with these communities.

year: 2025-08-01