title: Heegner cycles and congruences between anticyclotomic p-adic L-functions over CM-extensions

authors: Delbourgo, Daniel

subjects: Science & Technology

abstract: Let E be a CM-field, and suppose that f, g are two primitive Hilbert cusp forms over E⁺ of weight 2 satisfying a congruence modulo λʳ. Under appropriate hypotheses, we show that the complex L-values of f and g twisted by a ring class character over E, and divided by the motivic periods, also satisfy a congruence relation mod λʳ (after removing some Euler factors). We treat both the even and odd cases for the sign in the functional equation – this generalizes classical work of Vatsal [23] on congruences between elliptic modular forms twisted by Dirichlet characters. In the odd case, we also show that the p-adic logarithms of Heegner points attached to f and g satisfy a congruence relation modulo λʳ, thus extending recent work of Kriz and Li [17] concerning elliptic modular forms.

text: Heegner cycles and congruences between anticyclotomic p-adic L-functions over CM-extensions Let E be a CM-field, and suppose that f, g are two primitive Hilbert cusp forms over E⁺ of weight 2 satisfying a congruence modulo λʳ. Under appropriate hypotheses, we show that the complex L-values of f and g twisted by a ring class character over E, and divided by the motivic periods, also satisfy a congruence relation mod λʳ (after removing some Euler factors). We treat both the even and odd cases for the sign in the functional equation – this generalizes classical work of Vatsal [23] on congruences between elliptic modular forms twisted by Dirichlet characters. In the odd case, we also show that the p-adic logarithms of Heegner points attached to f and g satisfy a congruence relation modulo λʳ, thus extending recent work of Kriz and Li [17] concerning elliptic modular forms.

year: 2020

title: Treatment of hemp fibres for use in rotational moulding

authors: Oliveira, Maria A.S.

subjects: Hemp fibre

abstract: The benefit of using alkali-treated hemp fibre as the reinforcement for rotationally moulded evaluated in this research. Untreated and alkali treated hemp fibre were characterised using different techniques such as scanning electron microscopy (SEM), thermal analysis, and Fourier transform infrared spectroscopy (FT-IR). These techniques showed that the alkali treatment removed non-cellulosic components from hemp fibres, which improved their separation and thermal resistance. Composites with alkali treated fibre resisted the exposure to elevated temperatures for prolonged periods (characteristic of the rotational moulding process) with no apparent signs of thermal degradation, unlike when untreated fibre was used. The effect of using maleic anhydride grafted polyethylene (MAPE) as a coupling agent was also investigated. The addition of 3 wt% MAPE improved the properties tensile strength and Young’s modulus of composites with treated hemp fibre, which was attributed to better fibre-matrix adhesion. Different fibre contents were assessed in this research to produce rotationally moulded composites; a poor fibre distribution was observed above 5 wt% fibre content, which resulted in low tensile strength and Young’s modulus.

text: Treatment of hemp fibres for use in rotational moulding The benefit of using alkali-treated hemp fibre as the reinforcement for rotationally moulded evaluated in this research. Untreated and alkali treated hemp fibre were characterised using different techniques such as scanning electron microscopy (SEM), thermal analysis, and Fourier transform infrared spectroscopy (FT-IR). These techniques showed that the alkali treatment removed non-cellulosic components from hemp fibres, which improved their separation and thermal resistance. Composites with alkali treated fibre resisted the exposure to elevated temperatures for prolonged periods (characteristic of the rotational moulding process) with no apparent signs of thermal degradation, unlike when untreated fibre was used. The effect of using maleic anhydride grafted polyethylene (MAPE) as a coupling agent was also investigated. The addition of 3 wt% MAPE improved the properties tensile strength and Young’s modulus of composites with treated hemp fibre, which was attributed to better fibre-matrix adhesion. Different fibre contents were assessed in this research to produce rotationally moulded composites; a poor fibre distribution was observed above 5 wt% fibre content, which resulted in low tensile strength and Young’s modulus.

year: 2021

title: Harnessing Indigenous Tweets: The Reo Maori Twitter corpus

authors: Trye, David

subjects: Science & Technology

abstract: Te reo Māori, the Indigenous language of Aotearoa New Zealand, is a distinctive feature of the nation’s cultural heritage. This paper documents our efforts to build a corpus of 79,000 Māori-language tweets using computational methods. The Reo Māori Twitter (RMT) Corpus was created by targeting Māori-language users identified by the Indigenous Tweets website, pre-processing their data and filtering out non-Māori tweets, together with other sources of noise. Our motivation for creating such a resource is three-fold: (1) it serves as a rich and unique dataset for linguistic analysis of te reo Māori on social media; (2) it can be used as training data to develop and augment Natural Language Processing (NLP) tools with robust, real-world Māori-language applications; and (3) it will potentially promote awareness of, and encourage positive interaction with, the growing community of Māori tweeters, thereby increasing the use and visibility of te reo Māori in an online environment. While the corpus captures data from 2007 to 2020, our analysis shows that the number of tweets in the RMT Corpus peaked in 2014, and the number of active tweeters peaked in 2017, although at least 600 users were still active in 2020. To the best of our knowledge, the RMT Corpus is the largest publicly-available collection of social media data containing (almost) exclusively Māori text, making it a useful resource for language experts, NLP developers and Indigenous researchers alike.

text: Harnessing Indigenous Tweets: The Reo Maori Twitter corpus Te reo Māori, the Indigenous language of Aotearoa New Zealand, is a distinctive feature of the nation’s cultural heritage. This paper documents our efforts to build a corpus of 79,000 Māori-language tweets using computational methods. The Reo Māori Twitter (RMT) Corpus was created by targeting Māori-language users identified by the Indigenous Tweets website, pre-processing their data and filtering out non-Māori tweets, together with other sources of noise. Our motivation for creating such a resource is three-fold: (1) it serves as a rich and unique dataset for linguistic analysis of te reo Māori on social media; (2) it can be used as training data to develop and augment Natural Language Processing (NLP) tools with robust, real-world Māori-language applications; and (3) it will potentially promote awareness of, and encourage positive interaction with, the growing community of Māori tweeters, thereby increasing the use and visibility of te reo Māori in an online environment. While the corpus captures data from 2007 to 2020, our analysis shows that the number of tweets in the RMT Corpus peaked in 2014, and the number of active tweeters peaked in 2017, although at least 600 users were still active in 2020. To the best of our knowledge, the RMT Corpus is the largest publicly-available collection of social media data containing (almost) exclusively Māori text, making it a useful resource for language experts, NLP developers and Indigenous researchers alike.

year: 2022-02-14