title: Distribution of Pfiesteria piscicida cyst populations in sediments of the Delaware Inland Bays, USA

authors: Coyne, Kathryn J.

subjects: Cyst

abstract: The toxic dinoflagellate, Pfiesteria piscicida, is a common constituent of the phytoplankton community in the Delaware Inland Bays, USA. In this study, molecular methods were used to investigate the distributions of benthic stages (cysts) of P. piscicida in sediment cores from the Delaware Inland Bays. Cores from 35 sites were partitioned into nephloid and anoxic layers and analyzed for P. piscicida by nested amplification of the 18S rDNA gene using P. piscicida-specific primers. The presence of inhibitory substances in the PCR reaction was evaluated by inclusion of an exogenous control DNA in the extraction buffer, thus eliminating samples that may yield false-negative results. Our results indicate a patchy distribution of P. piscicida in sediments of the Delaware Inland Bays, with distinct differences between each of the three bays. Overall, P. piscicida was found more frequently in sediments from Rehoboth Bay compared to Indian River and Little Assawoman Bays. These differences suggest (i) that populations of P. piscicida may be more widely distributed in Rehoboth Bay, (ii) that populations of P. piscicida may have been introduced to Rehoboth Bay at an earlier time, (iii) that past blooms of P. piscicida in Rehoboth Bay estuaries may have seeded the sediments with higher numbers of cysts, and/or (iv) that Rehoboth Bay sediments may be more resistant to clearing due to storm turbulence.

text: Distribution of Pfiesteria piscicida cyst populations in sediments of the Delaware Inland Bays, USA The toxic dinoflagellate, Pfiesteria piscicida, is a common constituent of the phytoplankton community in the Delaware Inland Bays, USA. In this study, molecular methods were used to investigate the distributions of benthic stages (cysts) of P. piscicida in sediment cores from the Delaware Inland Bays. Cores from 35 sites were partitioned into nephloid and anoxic layers and analyzed for P. piscicida by nested amplification of the 18S rDNA gene using P. piscicida-specific primers. The presence of inhibitory substances in the PCR reaction was evaluated by inclusion of an exogenous control DNA in the extraction buffer, thus eliminating samples that may yield false-negative results. Our results indicate a patchy distribution of P. piscicida in sediments of the Delaware Inland Bays, with distinct differences between each of the three bays. Overall, P. piscicida was found more frequently in sediments from Rehoboth Bay compared to Indian River and Little Assawoman Bays. These differences suggest (i) that populations of P. piscicida may be more widely distributed in Rehoboth Bay, (ii) that populations of P. piscicida may have been introduced to Rehoboth Bay at an earlier time, (iii) that past blooms of P. piscicida in Rehoboth Bay estuaries may have seeded the sediments with higher numbers of cysts, and/or (iv) that Rehoboth Bay sediments may be more resistant to clearing due to storm turbulence.

year: 2006

title: The investigation of multi-storied Japanese timber pagodas during earthquake events and the application of non-linear joints within virtual models

authors: Roux, Philippus Jacobus

subjects: Timber

abstract: This paper investigates the structural mechanisms contributing to the excellent performance of Japanese pagodas during earthquake events and applies them to modern multi-storeyed timber structure models. Horyu-ji Pagoda was used as a basis for the modelling of the pagoda structure. 

It was discovered that there were six major mechanisms, these were; base isolation joints, sliding friction joints, rocking column joints, nuki joints, a balancing toy effect and the presence of a central pillar (shin-bashira). The first four unique joints were chosen to investigate further for practicality reasons, and they were added to a generic three-storied timber model. These models had different earthquake time histories applied to them and output data was collected using non-linear time history (NLTH) analysis. They key output data that was analysed was the acceleration, displacement and storey drift at each level of the different models. The energy dissipation within the models were also investigated. It was found that each of the unique joints had a certain strength and weakness in decreasing the effects of the earthquake on the structure, however when all of them were used together the best results were seen.

The combined mechanisms model had an average decrease of 43% in peak acceleration, 50% in average acceleration, 31% in peak displacement, 37% in peak storey drift, 65% in maximum internal energy and 81% in residual energy. The model had a 13% increase in peak displacement when considering horizontal loading due to wind. These differences were observed when comparing the combined mechanisms model to a generic timber model with joints that were all linear and moment resisting.

text: The investigation of multi-storied Japanese timber pagodas during earthquake events and the application of non-linear joints within virtual models This paper investigates the structural mechanisms contributing to the excellent performance of Japanese pagodas during earthquake events and applies them to modern multi-storeyed timber structure models. Horyu-ji Pagoda was used as a basis for the modelling of the pagoda structure. 

It was discovered that there were six major mechanisms, these were; base isolation joints, sliding friction joints, rocking column joints, nuki joints, a balancing toy effect and the presence of a central pillar (shin-bashira). The first four unique joints were chosen to investigate further for practicality reasons, and they were added to a generic three-storied timber model. These models had different earthquake time histories applied to them and output data was collected using non-linear time history (NLTH) analysis. They key output data that was analysed was the acceleration, displacement and storey drift at each level of the different models. The energy dissipation within the models were also investigated. It was found that each of the unique joints had a certain strength and weakness in decreasing the effects of the earthquake on the structure, however when all of them were used together the best results were seen.

The combined mechanisms model had an average decrease of 43% in peak acceleration, 50% in average acceleration, 31% in peak displacement, 37% in peak storey drift, 65% in maximum internal energy and 81% in residual energy. The model had a 13% increase in peak displacement when considering horizontal loading due to wind. These differences were observed when comparing the combined mechanisms model to a generic timber model with joints that were all linear and moment resisting.

year: 2022

title: The Treaty of Waitangi and Research Ethics in Aotearoa

authors: Hudson, Maui

subjects: Treaty of Waitangi

abstract: Researchers, when engaging with Māori communities, are in a process of relationship building and this process can be guided by the principles of the Treaty of Waitangi, partnership, participation and protection. The main concerns for many indigenous peoples in research revolve around respect for their indigenous rights, control over research processes and reciprocity within research relationships to ensure that equitable benefits are realised within indigenous groups. Māori have identified similar issues and these concerns can be aligned with the principles of the Treaty of Waitangi. The relevance of the Treaty of Waitangi to research ethics is discussed and this paper suggests a revised interpretation of the treaty principles to incorporate the range of ethical issues that Māori have expressed as important.

text: The Treaty of Waitangi and Research Ethics in Aotearoa Researchers, when engaging with Māori communities, are in a process of relationship building and this process can be guided by the principles of the Treaty of Waitangi, partnership, participation and protection. The main concerns for many indigenous peoples in research revolve around respect for their indigenous rights, control over research processes and reciprocity within research relationships to ensure that equitable benefits are realised within indigenous groups. Māori have identified similar issues and these concerns can be aligned with the principles of the Treaty of Waitangi. The relevance of the Treaty of Waitangi to research ethics is discussed and this paper suggests a revised interpretation of the treaty principles to incorporate the range of ethical issues that Māori have expressed as important.

year: 2009