Temporal disambiguation of relative temporal expressions in clinical texts using temporally fine-tuned contextual word embeddings.

Temporal reasoning is the ability to extract and assimilate temporal information to reconstruct a series of events such that they can be reasoned over to answer questions involving time. Temporal reasoning in the clinical domain is challenging due to specialized medical terms and nomenclature, shorthand notation, fragmented text, a variety of writing styles used by different medical units, redundancy of information that has to be reconciled, and an increased number of temporal references as compared to general domain texts. Work in the area of clinical temporal reasoning has progressed, but the current state-of-the-art still has a ways to go before practical application in the clinical setting will be possible. Much of the current work in this field is focused on direct and explicit temporal expressions and identifying temporal relations. However, there is little work focused on relative temporal expressions, which can be difficult to normalize, but are vital to ordering events on a timeline. This work introduces a new temporal expression recognition and normalization tool, Chrono, that normalizes temporal expressions into both SCATE and TimeML schemes. Chrono advances clinical timeline extraction as it is capable of identifying more vague and relative temporal expressions than the current state-of-the-art and utilizes contextualized word embeddings from fine-tuned BERT models to disambiguate temporal types, which achieves state-of-the-art performance on relative temporal expressions. In addition, this work shows that fine-tuning BERT models on temporal tasks modifies the contextualized embeddings so that they achieve improved performance in classical SVM and CNN classifiers. Finally, this works provides a new tool for linking temporal expressions to events or other entities by introducing a novel method to identify which tokens an entire temporal expression is paying the most attention to by summarizing the attention weight matrices output by BERT models

The One with the Social Network Analysis: the extraction, analysis and modelling of temporal social networks from narratives

Narratives tell us about the people, cultures, and time periods in and about which they were written. Therefore, narrative analysis is a powerful tool for understanding culture. One way to analyse narratives is through their social networks, however extracting the network is a complex task. Manually recording characters and their interactions is an accurate, but time consuming method for narrative social network extraction, however efficient automatic extraction methods may introduce errors. In this thesis, we perform a detailed comparative study of narrative social network extraction techniques, and investigate the effect the techniques have on the analysis of the narrative. We use the 1994–2004 television series Friends as a case study to model and compare extraction techniques. By designing a simulated social network and observation processes resembling different network extraction techniques, we find that automated network extraction methods are reliable for computing many network metrics, but can distort the clustering coefficient. Our comparison of extraction techniques allows for many more narratives to be extracted and analysed efficiently. We also analyse and model the social networks of Friends, to gain new insights into the the series, and what made it successful. We show which are the most important characters and relationships, and through modelling social network features we find the most informative features to predict success. Our analysis of Friends provides an example and a building block for deeper understanding about particular narratives and narratives in general.Thesis (MPhil) -- University of Adelaide, School of Mathematical Sciences, 201