title: PolyLM: Learning about polysemy through language modeling

authors: Ansell, Alan

abstract: To avoid the “meaning conflation deficiency” of word embeddings, a number of models have aimed to embed individual word senses. These methods at one time performed well on tasks such as word sense induction (WSI), but they have since been overtaken by task-specific techniques which exploit contextualized embeddings. However, sense embeddings and contextualization need not be mutually exclusive. We introduce PolyLM, a method which formulates the task of learning sense embeddings as a language modeling problem, allowing contextualization techniques to be applied. PolyLM is based on two underlying assumptions about word senses: firstly, that the probability of a word occurring in a given context is equal to the sum of the probabilities of its individual senses occurring; and secondly, that for a given occurrence of a word, one of its senses tends to be much more plausible in the context than the others. We evaluate PolyLM on WSI, showing that it performs considerably better than previous sense embedding techniques, and matches the current state-of-the-art specialized WSI method despite having six times fewer parameters. Code and pre-trained models are available at https://github.com/AlanAnsell/PolyLM.

text: PolyLM: Learning about polysemy through language modeling To avoid the “meaning conflation deficiency” of word embeddings, a number of models have aimed to embed individual word senses. These methods at one time performed well on tasks such as word sense induction (WSI), but they have since been overtaken by task-specific techniques which exploit contextualized embeddings. However, sense embeddings and contextualization need not be mutually exclusive. We introduce PolyLM, a method which formulates the task of learning sense embeddings as a language modeling problem, allowing contextualization techniques to be applied. PolyLM is based on two underlying assumptions about word senses: firstly, that the probability of a word occurring in a given context is equal to the sum of the probabilities of its individual senses occurring; and secondly, that for a given occurrence of a word, one of its senses tends to be much more plausible in the context than the others. We evaluate PolyLM on WSI, showing that it performs considerably better than previous sense embedding techniques, and matches the current state-of-the-art specialized WSI method despite having six times fewer parameters. Code and pre-trained models are available at https://github.com/AlanAnsell/PolyLM.

year: 2021

title: Nitrate removal and hydraulic performance of organic carbon for use in denitrification beds

authors: Cameron, Stewart Graham

subjects: denitrification

abstract: Denitrification beds are a cost-effective technology for removing nitrate from point source discharge. To date, field trials and operational beds have primarily used wood media as the carbon source; however, the use of alternative more labile carbon media could provide for increased removal rate, lower installation costs and reduced bed size. While previous laboratory experiments have investigated the potential of alternative carbon sources, these studies were typically of short duration and small scale and did not necessarily provide reliable information for denitrification bed design purposes. To address this issue, we compared nitrate removal, hydraulic and nutrient leaching characteristics of nine different carbon substrates in 0.2 m³ barrels, at 14 and 23.5 °C over a 23-month period. Mean nitrate removal rates for the period 10–23 months were 19.8 and 15 g N m⁻³ d⁻¹ (maize cobs), 7.8 and 10.5 g N m⁻³ d⁻¹ (green waste), 5.8 and 7.8 g N m−³ d⁻¹ (wheat straw), 3.0 and 4.9 g N m−3 d−1 (softwood), and 3.3 and 4.4 g N m−³ d⁻¹ (hardwood) for the 14 and 23.5 °C treatments, respectively. Maize cobs provided a 3–6.5-fold increase in nitrate removal over wood media, without prohibitive decrease in hydraulic conductivity, but had higher rates of nutrient leaching at start-up. Significant difference in removal rate occurred between the 14 and 23.5 °C treatments, with the mean Q₁₀ temperature coefficient = 1.6 for all media types in the period 10–23 months.

text: Nitrate removal and hydraulic performance of organic carbon for use in denitrification beds Denitrification beds are a cost-effective technology for removing nitrate from point source discharge. To date, field trials and operational beds have primarily used wood media as the carbon source; however, the use of alternative more labile carbon media could provide for increased removal rate, lower installation costs and reduced bed size. While previous laboratory experiments have investigated the potential of alternative carbon sources, these studies were typically of short duration and small scale and did not necessarily provide reliable information for denitrification bed design purposes. To address this issue, we compared nitrate removal, hydraulic and nutrient leaching characteristics of nine different carbon substrates in 0.2 m³ barrels, at 14 and 23.5 °C over a 23-month period. Mean nitrate removal rates for the period 10–23 months were 19.8 and 15 g N m⁻³ d⁻¹ (maize cobs), 7.8 and 10.5 g N m⁻³ d⁻¹ (green waste), 5.8 and 7.8 g N m−³ d⁻¹ (wheat straw), 3.0 and 4.9 g N m−3 d−1 (softwood), and 3.3 and 4.4 g N m−³ d⁻¹ (hardwood) for the 14 and 23.5 °C treatments, respectively. Maize cobs provided a 3–6.5-fold increase in nitrate removal over wood media, without prohibitive decrease in hydraulic conductivity, but had higher rates of nutrient leaching at start-up. Significant difference in removal rate occurred between the 14 and 23.5 °C treatments, with the mean Q₁₀ temperature coefficient = 1.6 for all media types in the period 10–23 months.

year: 2010

title: Merea Wikiriwhi and George Thomas Wilkinson

authors: Hart, Philip

abstract: Merea Wikiriwhi was one of the few women to invest in Te Aroha mining. Her life has been traced in as much detail as can be found because so little has survived about the lives of Maori women. As George Thomas Wilkinson’s surviving diaries reveal his importance in her life, his story was included as well, concentrating on his personal life rather than his official career. 
Merea was a member of several Ohinemuri hapu, with links through whakapapa to some of their more senior rangatira. Mostly living at or near Waitoki, between Paeroa and Te Aroha, she lived a frugal life, not wasting the income she received from land sales. These sales first required her to insist on her rights both in the land court and in a convoluted legal battle over a will signed in her favour by a distant relative. Over time, she would sell most of her land, but never became entirely landless. She invested in only one mining claim, but in the 1930s joined others to claim that the government was not paying them goldfields revenue for land they had sold.
George Thomas Wilkinson entered her life in 1880, when he was the ‘native agent’ in Hauraki. Despite having fought against Maori and nearly being killed, his surviving diaries reveal that he lived in the manner of a Pakeha Maori with three Maori women (simultaneously for a time), having children both by Merea and the woman he would eventually marry. Wilkinson had close friendships with many Maori and Pakeha Maori, and his genuine regard for them is reflected not only in his attempting, in his official capacity, to be fair to their interests – even as he assisted the government to separate them from their land – but in particular by his affection for a young girl, Wairingiringi, who shared his house in Thames. Although he and Merea would part, he tried to ensure that her children, like all his children, would do well in a Pakeha world.

text: Merea Wikiriwhi and George Thomas Wilkinson Merea Wikiriwhi was one of the few women to invest in Te Aroha mining. Her life has been traced in as much detail as can be found because so little has survived about the lives of Maori women. As George Thomas Wilkinson’s surviving diaries reveal his importance in her life, his story was included as well, concentrating on his personal life rather than his official career. 
Merea was a member of several Ohinemuri hapu, with links through whakapapa to some of their more senior rangatira. Mostly living at or near Waitoki, between Paeroa and Te Aroha, she lived a frugal life, not wasting the income she received from land sales. These sales first required her to insist on her rights both in the land court and in a convoluted legal battle over a will signed in her favour by a distant relative. Over time, she would sell most of her land, but never became entirely landless. She invested in only one mining claim, but in the 1930s joined others to claim that the government was not paying them goldfields revenue for land they had sold.
George Thomas Wilkinson entered her life in 1880, when he was the ‘native agent’ in Hauraki. Despite having fought against Maori and nearly being killed, his surviving diaries reveal that he lived in the manner of a Pakeha Maori with three Maori women (simultaneously for a time), having children both by Merea and the woman he would eventually marry. Wilkinson had close friendships with many Maori and Pakeha Maori, and his genuine regard for them is reflected not only in his attempting, in his official capacity, to be fair to their interests – even as he assisted the government to separate them from their land – but in particular by his affection for a young girl, Wairingiringi, who shared his house in Thames. Although he and Merea would part, he tried to ensure that her children, like all his children, would do well in a Pakeha world.

year: 2016