title: Spikes and matter inhomogeneities in massless scalar field models

authors: Coley, A.A.

subjects: Science & Technology

abstract: We shall discuss the general relativistic generation of spikes in a massless scalar field or stiff perfect fluid model. We first investigate orthogonally transitive (OT) G 2 stiff fluid spike models both heuristically and numerically, and give a new exact OT G 2 stiff fluid spike solution. We then present a new two-parameter family of non-OT G 2 stiff fluid spike solutions, obtained by the generalization of non-OT G 2 vacuum spike solutions to the stiff fluid case by applying Geroch's transformation on a Jacobs seed. The dynamics of these new stiff fluid spike solutions is qualitatively different from that of the vacuum spike solutions in that the matter (stiff fluid) feels the spike directly and the stiff fluid spike solution can end up with a permanent spike. We then derive the evolution equations of non-OT G 2 stiff fluid models, including a second perfect fluid, in full generality, and briefly discuss some of their qualitative properties and their potential numerical analysis. Finally, we discuss how a fluid, and especially a stiff fluid or massless scalar field, affects the physics of the generation of spikes.

text: Spikes and matter inhomogeneities in massless scalar field models We shall discuss the general relativistic generation of spikes in a massless scalar field or stiff perfect fluid model. We first investigate orthogonally transitive (OT) G 2 stiff fluid spike models both heuristically and numerically, and give a new exact OT G 2 stiff fluid spike solution. We then present a new two-parameter family of non-OT G 2 stiff fluid spike solutions, obtained by the generalization of non-OT G 2 vacuum spike solutions to the stiff fluid case by applying Geroch's transformation on a Jacobs seed. The dynamics of these new stiff fluid spike solutions is qualitatively different from that of the vacuum spike solutions in that the matter (stiff fluid) feels the spike directly and the stiff fluid spike solution can end up with a permanent spike. We then derive the evolution equations of non-OT G 2 stiff fluid models, including a second perfect fluid, in full generality, and briefly discuss some of their qualitative properties and their potential numerical analysis. Finally, we discuss how a fluid, and especially a stiff fluid or massless scalar field, affects the physics of the generation of spikes.

year: 2016-01-07

title: Salinity indicators in sediment through the fluvial-to-marine transition (Fraser River, Canada).

authors: Dashtgard, Shahin E.

subjects: Canada

abstract: Many sediment attributes have been proposed as proxies for determining salinity conditions under which sediment is deposited, and six attributes (Sr/Ba-HAc, Sr/Ba-NH4Ac, δ13Corg, C/N, and the relative abundances and concentrations of dinoflagellate cysts) are compared here. In this paper, sediment attributes from the Fraser River Delta, Canada and surrounding coastal areas are compared by depositional position along the fluvial-to-marine transition, by salinity, and by sedimentological characteristics. Along the fluvial-to-marine transition, most attributes exhibit distinct trends between parts of the river that experience sustained marine water (saltwater) influence over seasonal and tidal timeframes, and parts that experience only freshwater or periodic saltwater influence. No attributes are reliable indicators of depositional position where saltwater incursion is short lived or where water is fresh. Where marine influence is sustained, Sr/Ba-HAc and Sr/Ba-NH4Ac are the most reliable positional indicators along the fluvial-to-marine transition. When compared strictly to salinity, Sr/Ba-HAc, Sr/Ba-NH4Ac, and δ13Corg all correlate predictably except in delta front and prodelta settings. Our data show that all six sediment attributes are heavily impacted by river-derived sedimentation, and it is not appropriate to compare values from strongly river-influenced settings (e.g., deltas) with those from weakly river-influenced settings (e.g., bays and estuaries).

text: Salinity indicators in sediment through the fluvial-to-marine transition (Fraser River, Canada). Many sediment attributes have been proposed as proxies for determining salinity conditions under which sediment is deposited, and six attributes (Sr/Ba-HAc, Sr/Ba-NH4Ac, δ13Corg, C/N, and the relative abundances and concentrations of dinoflagellate cysts) are compared here. In this paper, sediment attributes from the Fraser River Delta, Canada and surrounding coastal areas are compared by depositional position along the fluvial-to-marine transition, by salinity, and by sedimentological characteristics. Along the fluvial-to-marine transition, most attributes exhibit distinct trends between parts of the river that experience sustained marine water (saltwater) influence over seasonal and tidal timeframes, and parts that experience only freshwater or periodic saltwater influence. No attributes are reliable indicators of depositional position where saltwater incursion is short lived or where water is fresh. Where marine influence is sustained, Sr/Ba-HAc and Sr/Ba-NH4Ac are the most reliable positional indicators along the fluvial-to-marine transition. When compared strictly to salinity, Sr/Ba-HAc, Sr/Ba-NH4Ac, and δ13Corg all correlate predictably except in delta front and prodelta settings. Our data show that all six sediment attributes are heavily impacted by river-derived sedimentation, and it is not appropriate to compare values from strongly river-influenced settings (e.g., deltas) with those from weakly river-influenced settings (e.g., bays and estuaries).

year: 2022

title: Ko Te Kawa Tūpanapana i ngā Hau Tūpua a Tāwhiri-mātea : The validation, revitalisation and enhancement of Māori environment knowledge of weather and climate

authors: Skipper, Apanui Sonny

subjects: Maori Environmental knowledge

abstract: KO TE KAWA TŪPANAPANA I NGĀ HAU TŪPUA A TĀWHIRI-MĀTEA – THE RITUALISTIC FORMS GOVERNING THE SUPERNATURAL WINDS OF TĀWHIRI-MĀTEA
Mankind has always gazed skyward observing the im immense power generated by forked lightning when it strikes the land. The resounding thunder booming across the landscape never failed to capture the awe and imagination of a people. Māori were no different. The legacy of their Polynesian ancestors, who populated most of the Islands of Te Moana-nui-a-Kiwa, the largest ocean on the planet, based on belief, courage, and navigational expertise, honed over many millenia, reached Aotearoa approximately in the 12 century. These highly skilled ancestors from the tropics applied a formalised process of settling a new land. It also required their own weatherlore to be recalibrated to the local conditions, in order to survive in a much harsher, colder climate.

Over the centuries the descendants of these early Polynesian settlers, developed an extensive localised knowledge of weather, climate, and seasonal indicators to accurately predict daily weather, monthly or annual climate conditions. The ongoing lessons learned especially after experiencing a fatality were incorporated into cultural practices of important everyday activities such as ahuwhenua, te mahi hī ika, kohi rongoā, whakaako tamariki, gathering pounamu, whakatū rāhui, and kaitiakitanga, in order to minimise further loss of life.

Formal recognition of these contributions was made at the inaugural Māori Climate Forum in Wellington in 2003, where a number of Māori elders highlighted the importance of giving a greater account of Māori knowledge of environmental change. Among the many priorities identified for research at this forum, an opportunity based on a challenge from a Māori elder led to the development of a pilot project to explore traditional Māori understandings of weather–climate variability and change. 

One of the key outcomes from this work was the identification of Māori environmental indicators to anticipate local weather and climate conditions and thereby manage the risk associated with weather-climate extremes. However, in spite of the work achieved, there remain unanswered questions about the use and ongoing efficacy of environmental indicators to forecast and monitor weather and climate risks, including how new opportunities might be created to promote learning about subtle signals in nature that can reveal much about changes in weather and climate conditions. 

Due to the fact that many of the elders that provided the basis of this thesis have passed away, a great sense of responsibility has remained with me to complete this research. To identify the gaps in the previous research, to ground-truth it, to consolidate and carefully document the level of localised environmental knowledge of weather and climate specifically with iwi from Tainui-Hauraki, Te Whānau-a-Apanui, and Ngāi Tahu. A total of 56 interviews and 17 group wānanga were conducted during 2009-2016. Examples of Māori Environmental Knowledge were also sourced from numerous personal conversations with knowledge holders from 1989-2003, adding to the body of knowledge that was analysed to provide further context. A conceptual framework coined `Ngā Whenu Tapu e Waru’ was created from identifying the key themes of the interviews to inform how Māori Environmental Knowledge was described in the three regions. This study has yielded understandings of wind, rain, thunder, lightning, and cloud classifications; weather and climate indicators; spiritual signs of misfortune and death; memory techniques; longitudinal weather predictions, and lunar calendars in each region.

This thesis is underpinned by a Kaupapa Māori theory and research methodology that links to a body of transformative research and literature conducted by Māori scholars based on the knowledge and experience of tūpuna  Māori. 

Heoti anō rā kei ngā kākahi whakairoiro, kei ngā matataiko, nau piki mai, nau kake mai ki tēnei wānanga nui whakaharahara.

text: Ko Te Kawa Tūpanapana i ngā Hau Tūpua a Tāwhiri-mātea : The validation, revitalisation and enhancement of Māori environment knowledge of weather and climate KO TE KAWA TŪPANAPANA I NGĀ HAU TŪPUA A TĀWHIRI-MĀTEA – THE RITUALISTIC FORMS GOVERNING THE SUPERNATURAL WINDS OF TĀWHIRI-MĀTEA
Mankind has always gazed skyward observing the im immense power generated by forked lightning when it strikes the land. The resounding thunder booming across the landscape never failed to capture the awe and imagination of a people. Māori were no different. The legacy of their Polynesian ancestors, who populated most of the Islands of Te Moana-nui-a-Kiwa, the largest ocean on the planet, based on belief, courage, and navigational expertise, honed over many millenia, reached Aotearoa approximately in the 12 century. These highly skilled ancestors from the tropics applied a formalised process of settling a new land. It also required their own weatherlore to be recalibrated to the local conditions, in order to survive in a much harsher, colder climate.

Over the centuries the descendants of these early Polynesian settlers, developed an extensive localised knowledge of weather, climate, and seasonal indicators to accurately predict daily weather, monthly or annual climate conditions. The ongoing lessons learned especially after experiencing a fatality were incorporated into cultural practices of important everyday activities such as ahuwhenua, te mahi hī ika, kohi rongoā, whakaako tamariki, gathering pounamu, whakatū rāhui, and kaitiakitanga, in order to minimise further loss of life.

Formal recognition of these contributions was made at the inaugural Māori Climate Forum in Wellington in 2003, where a number of Māori elders highlighted the importance of giving a greater account of Māori knowledge of environmental change. Among the many priorities identified for research at this forum, an opportunity based on a challenge from a Māori elder led to the development of a pilot project to explore traditional Māori understandings of weather–climate variability and change. 

One of the key outcomes from this work was the identification of Māori environmental indicators to anticipate local weather and climate conditions and thereby manage the risk associated with weather-climate extremes. However, in spite of the work achieved, there remain unanswered questions about the use and ongoing efficacy of environmental indicators to forecast and monitor weather and climate risks, including how new opportunities might be created to promote learning about subtle signals in nature that can reveal much about changes in weather and climate conditions. 

Due to the fact that many of the elders that provided the basis of this thesis have passed away, a great sense of responsibility has remained with me to complete this research. To identify the gaps in the previous research, to ground-truth it, to consolidate and carefully document the level of localised environmental knowledge of weather and climate specifically with iwi from Tainui-Hauraki, Te Whānau-a-Apanui, and Ngāi Tahu. A total of 56 interviews and 17 group wānanga were conducted during 2009-2016. Examples of Māori Environmental Knowledge were also sourced from numerous personal conversations with knowledge holders from 1989-2003, adding to the body of knowledge that was analysed to provide further context. A conceptual framework coined `Ngā Whenu Tapu e Waru’ was created from identifying the key themes of the interviews to inform how Māori Environmental Knowledge was described in the three regions. This study has yielded understandings of wind, rain, thunder, lightning, and cloud classifications; weather and climate indicators; spiritual signs of misfortune and death; memory techniques; longitudinal weather predictions, and lunar calendars in each region.

This thesis is underpinned by a Kaupapa Māori theory and research methodology that links to a body of transformative research and literature conducted by Māori scholars based on the knowledge and experience of tūpuna  Māori. 

Heoti anō rā kei ngā kākahi whakairoiro, kei ngā matataiko, nau piki mai, nau kake mai ki tēnei wānanga nui whakaharahara.

year: 2020