title: Supporting Collocation Learning

authors: Wu, Shaoqun

subjects: Collocation teaching and learning

abstract: Collocations are of great importance for second language learners. Knowledge of them plays a key role in producing language accurately and fluently. But such knowledge is difficult to acquire, simply because there is so much of it. Collocation resources for learners are limited. Printed dictionaries are restricted in size, and only provide rudimentary search and retrieval options. Free online resources are rare, and learners find the language data they offer hard to interpret. Online collocation exercises are inadequate and scattered, making it difficult to acquire collocations in a systematic way. This thesis makes two claims: (1) corpus data can be presented in different ways to facilitate effective collocation learning, and (2) a computer system can be constructed to help learners systematically strengthen and enhance their collocation knowledge. To investigate the first claim, an enormous Web-derived corpus was processed, filtered, and organized into three searchable digital library collections that support different aspects of collocation learning. Each of these constitutes a vast concordance whose entries are presented in ways that help students use collocations more effectively in their writing. To provide extended context, concordance data is linked to illustrative sample sentences, both on the live Web and in the British National Corpus. Two evaluations were conducted, both of which suggest that these collections can and do help improve student writing. For the second claim, a system was built that automatically identifies collocations in texts that teachers or students provide, using natural language processing techniques. Students study, collect and store collocations of interest while reading. Teachers construct collocation exercises to consolidate what students have learned and amplify their knowledge. The system was evaluated with teachers and students in classroom settings, and positive outcomes were demonstrated. We believe that the deployment of computer-based collocation learning systems is an exciting development that will transform language learning.

text: Supporting Collocation Learning Collocations are of great importance for second language learners. Knowledge of them plays a key role in producing language accurately and fluently. But such knowledge is difficult to acquire, simply because there is so much of it. Collocation resources for learners are limited. Printed dictionaries are restricted in size, and only provide rudimentary search and retrieval options. Free online resources are rare, and learners find the language data they offer hard to interpret. Online collocation exercises are inadequate and scattered, making it difficult to acquire collocations in a systematic way. This thesis makes two claims: (1) corpus data can be presented in different ways to facilitate effective collocation learning, and (2) a computer system can be constructed to help learners systematically strengthen and enhance their collocation knowledge. To investigate the first claim, an enormous Web-derived corpus was processed, filtered, and organized into three searchable digital library collections that support different aspects of collocation learning. Each of these constitutes a vast concordance whose entries are presented in ways that help students use collocations more effectively in their writing. To provide extended context, concordance data is linked to illustrative sample sentences, both on the live Web and in the British National Corpus. Two evaluations were conducted, both of which suggest that these collections can and do help improve student writing. For the second claim, a system was built that automatically identifies collocations in texts that teachers or students provide, using natural language processing techniques. Students study, collect and store collocations of interest while reading. Teachers construct collocation exercises to consolidate what students have learned and amplify their knowledge. The system was evaluated with teachers and students in classroom settings, and positive outcomes were demonstrated. We believe that the deployment of computer-based collocation learning systems is an exciting development that will transform language learning.

year: 2010

title: Effects of organic matter complexation on partitioning of  first-row transition metals into calcite: cave-analogue crystal growth studies

authors: Lindeman, Ingrid

subjects: Speleothem

abstract: Speleothems are important archives of terrestrial paleoclimate due to their wide geographical coverage and the ability to date their growth layers using U-Th and U-Pb radiometric dating. Extensive research into various speleothem-based geochemical proxies has been undertaken in the last half century, and a significant number of proxies are now used routinely for reconstructions of paleoclimate including stable oxygen and carbon isotopes (known to respond to variations in rainfall and temperature), fluorescence (indicative of the quality and quantity of organic matter present in cave dripwaters) and speleothem minerology (e.g. fabric defects and nano-crystal aggregation). Trace element proxies in speleothems have also garnered attention, but the suite of trace elements used to date has primarily been limited to the alkali earth metals as they exhibit simple partitioning and are characterised by partition coefficients (Kd values) less than 1. Their role in karst systems is thus comparatively well constrained.

In contrast, the first-row transition metals have been the focus of only a few speleothem-based studies, despite recent evidence suggesting some of these metals (namely Co, Ni and Cu) may be useful additions to the current suite of trace element proxies already utilised. Thus, although theoretical distribution coefficient data are available for these metals, their partitioning behaviour into speleothem calcite is not well understood. Theoretical distribution coefficients are useful in understanding partitioning behaviour under certain conditions, but the non-thermodynamic nature of partition coefficients during calcite precipitation in most natural contexts requires partitioning behaviour under speleothem-specific conditions to be established. For instance, despite theoretical distribution coefficients being greater than 1 for Co, Ni and Cu, apparent partition coefficients (Kd app) calculated for these metals in actual speleothem samples are frequently less than 1 due to the dependence of Kd app on a number of factors including calcite precipitation rate, crystal morphology, and complexation reactions between natural organic matter (NOM) and trace ions. Indeed, complexation of first-row transition metals in speleothem-forming dripwaters has been shown to significantly alter the availability of these metals for incorporation into speleothem calcite. This study therefore aimed to investigate the partitioning behaviour of Co, Ni and Cu into calcite precipitated under karst-analogue conditions and in the presence of organic ligands to help establish these metals as viable speleothem-based paleoclimate proxies.

In order to do this, a suitable method for growing calcite under karst-analogue conditions was first established. All experiments were undertaken inside a purpose-built chamber that ensured precise control of temperature, humidity and pCO2, and calcite was grown in a manner analogous to that observed for natural speleothems, with calcite precipitation occurring as a result of CO2 degassing from a thin solution film. Observed growth rates and structural characterisation of the precipitated CaCO3 indicated the method developed was suitable for the desired purpose, and the partitioning data obtained subsequently was considered to be applicable to ‘real-world’ speleothem and cave dripwater samples.

The partitioning behaviour of Co, Ni and Cu into calcite grown under speleothem-like conditions was assessed, and speleothem-specific Kd values of ~ 4, 1 and 44, respectively, were determined. The relatively high inorganic Kd values determined for Co and Cu illustrate the reason why these divalent metals have frequently been overlooked as paleoclimate proxies in speleothems: metals with high partition coefficients are thought to exhibit complex partitioning behaviour and are significantly affected by PCP. However, further experiments carried out with organic ligands present in solution illustrated that the complexation of Co, Ni and Cu by nitrilotriacetic acid (NTA) and Suwanee River fulvic acid (SRFA) significantly altered their partitioning behaviour, with apparent partition coefficients reduced below 1 for all three metals. It was shown that partitioning of Co, Ni and Cu into calcite was controlled not only by their affinity for the calcite lattice (i.e. inorganic Kd values) but also by the dissociation of the metal-ligand complexes, and that the amount of ‘free’ metal available for incorporation into calcite was dependent on residence time and the dissociation constants of the complexes.

The results found in this study highlight the fact that the incorporation of the divalent first-row transition metals into speleothem calcite cannot be considered in terms of simple inorganic partitioning, as the widespread presence of NOM in karst systems will alter their partitioning behaviour significantly. Thus, although the use of these metals as speleothem-based proxies has previously been overlooked in favour of elements such as the alkali earth metals which exhibit simple partitioning (i.e. Kd << 1), in reality the NOM present in karst systems will reduce the effects of PCP on these divalent first-row metals, and they should in fact be considered as useful additions to the current range of paleo-proxies used.

text: Effects of organic matter complexation on partitioning of  first-row transition metals into calcite: cave-analogue crystal growth studies Speleothems are important archives of terrestrial paleoclimate due to their wide geographical coverage and the ability to date their growth layers using U-Th and U-Pb radiometric dating. Extensive research into various speleothem-based geochemical proxies has been undertaken in the last half century, and a significant number of proxies are now used routinely for reconstructions of paleoclimate including stable oxygen and carbon isotopes (known to respond to variations in rainfall and temperature), fluorescence (indicative of the quality and quantity of organic matter present in cave dripwaters) and speleothem minerology (e.g. fabric defects and nano-crystal aggregation). Trace element proxies in speleothems have also garnered attention, but the suite of trace elements used to date has primarily been limited to the alkali earth metals as they exhibit simple partitioning and are characterised by partition coefficients (Kd values) less than 1. Their role in karst systems is thus comparatively well constrained.

In contrast, the first-row transition metals have been the focus of only a few speleothem-based studies, despite recent evidence suggesting some of these metals (namely Co, Ni and Cu) may be useful additions to the current suite of trace element proxies already utilised. Thus, although theoretical distribution coefficient data are available for these metals, their partitioning behaviour into speleothem calcite is not well understood. Theoretical distribution coefficients are useful in understanding partitioning behaviour under certain conditions, but the non-thermodynamic nature of partition coefficients during calcite precipitation in most natural contexts requires partitioning behaviour under speleothem-specific conditions to be established. For instance, despite theoretical distribution coefficients being greater than 1 for Co, Ni and Cu, apparent partition coefficients (Kd app) calculated for these metals in actual speleothem samples are frequently less than 1 due to the dependence of Kd app on a number of factors including calcite precipitation rate, crystal morphology, and complexation reactions between natural organic matter (NOM) and trace ions. Indeed, complexation of first-row transition metals in speleothem-forming dripwaters has been shown to significantly alter the availability of these metals for incorporation into speleothem calcite. This study therefore aimed to investigate the partitioning behaviour of Co, Ni and Cu into calcite precipitated under karst-analogue conditions and in the presence of organic ligands to help establish these metals as viable speleothem-based paleoclimate proxies.

In order to do this, a suitable method for growing calcite under karst-analogue conditions was first established. All experiments were undertaken inside a purpose-built chamber that ensured precise control of temperature, humidity and pCO2, and calcite was grown in a manner analogous to that observed for natural speleothems, with calcite precipitation occurring as a result of CO2 degassing from a thin solution film. Observed growth rates and structural characterisation of the precipitated CaCO3 indicated the method developed was suitable for the desired purpose, and the partitioning data obtained subsequently was considered to be applicable to ‘real-world’ speleothem and cave dripwater samples.

The partitioning behaviour of Co, Ni and Cu into calcite grown under speleothem-like conditions was assessed, and speleothem-specific Kd values of ~ 4, 1 and 44, respectively, were determined. The relatively high inorganic Kd values determined for Co and Cu illustrate the reason why these divalent metals have frequently been overlooked as paleoclimate proxies in speleothems: metals with high partition coefficients are thought to exhibit complex partitioning behaviour and are significantly affected by PCP. However, further experiments carried out with organic ligands present in solution illustrated that the complexation of Co, Ni and Cu by nitrilotriacetic acid (NTA) and Suwanee River fulvic acid (SRFA) significantly altered their partitioning behaviour, with apparent partition coefficients reduced below 1 for all three metals. It was shown that partitioning of Co, Ni and Cu into calcite was controlled not only by their affinity for the calcite lattice (i.e. inorganic Kd values) but also by the dissociation of the metal-ligand complexes, and that the amount of ‘free’ metal available for incorporation into calcite was dependent on residence time and the dissociation constants of the complexes.

The results found in this study highlight the fact that the incorporation of the divalent first-row transition metals into speleothem calcite cannot be considered in terms of simple inorganic partitioning, as the widespread presence of NOM in karst systems will alter their partitioning behaviour significantly. Thus, although the use of these metals as speleothem-based proxies has previously been overlooked in favour of elements such as the alkali earth metals which exhibit simple partitioning (i.e. Kd << 1), in reality the NOM present in karst systems will reduce the effects of PCP on these divalent first-row metals, and they should in fact be considered as useful additions to the current range of paleo-proxies used.

year: 2020

title: Ahumai

authors: Temara, Pou

subjects: Pātere

abstract: E tika ana kia punarua te wānanga i ēnei pātere e rua nā te mea he mārama te kite iho o whatu he ōrite ētahi o ngā rārangi kupu, ngā whakaaro me ngā kareāroto ki te pātere a Ahumai. Ahakoa kāore i te takoto te ingoa o te kaitito i tēnei pātere, nā te ōrite o ētahi o ngā kupu, e taea te whakapae, nā te ringa kotahi ēnei pātere i waituhi? Kai roto hoki i te pātere nei e takaoto ana ngā rohe o Raukawa pērā i Wharepūhunga, me ngā tangata whai mana o tērā iwi pērā i a Tīkao. Hei taituarā ka hahua ake anō te kōrero a Turanga Te Mauparaoa ki te tata o te rohe o te iwi nāna te waiata nei, ki tōna rohe. Kāore te Māori e kī ‘nō tua ake nei tēnei pātere’ mēnā he tawhiti atu te iwi i tōna. Nō reira, ki taku wānanga, ehara tēnei pātere nō ngā iwi o Taranaki. He tawhiti rawa a Taranaki i Murupara. Hāunga a Raukawa, koia te iwi kai ‘tua ake nei’.

E tuku ana ahau i taku ihu kia puta. Ki te tapahia mai, e pai ana. E kī ana hoki au, ko te mea poto te titonga tuatahi, ko te mea roa te titonga o muri mai. He ariā te mea tuatahi nō te mea tuarua.

text: Ahumai E tika ana kia punarua te wānanga i ēnei pātere e rua nā te mea he mārama te kite iho o whatu he ōrite ētahi o ngā rārangi kupu, ngā whakaaro me ngā kareāroto ki te pātere a Ahumai. Ahakoa kāore i te takoto te ingoa o te kaitito i tēnei pātere, nā te ōrite o ētahi o ngā kupu, e taea te whakapae, nā te ringa kotahi ēnei pātere i waituhi? Kai roto hoki i te pātere nei e takaoto ana ngā rohe o Raukawa pērā i Wharepūhunga, me ngā tangata whai mana o tērā iwi pērā i a Tīkao. Hei taituarā ka hahua ake anō te kōrero a Turanga Te Mauparaoa ki te tata o te rohe o te iwi nāna te waiata nei, ki tōna rohe. Kāore te Māori e kī ‘nō tua ake nei tēnei pātere’ mēnā he tawhiti atu te iwi i tōna. Nō reira, ki taku wānanga, ehara tēnei pātere nō ngā iwi o Taranaki. He tawhiti rawa a Taranaki i Murupara. Hāunga a Raukawa, koia te iwi kai ‘tua ake nei’.

E tuku ana ahau i taku ihu kia puta. Ki te tapahia mai, e pai ana. E kī ana hoki au, ko te mea poto te titonga tuatahi, ko te mea roa te titonga o muri mai. He ariā te mea tuatahi nō te mea tuarua.

year: 2017