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Publications

Publications by LIAAD

2022

On-line atracurium dose prediction: a nonparametric approach.

Authors
Rocha C.; Mendonca T.; Silva M.E.;

Publication
2022 IEEE Conference on Control Technology and Applications, CCTA 2022

Abstract
This paper aims at contributing to personalize anesthetic drug administration during surgery. This study devel-ops an online robust model to predict the maintenance dose of atracurium necessary for the resulting effect, i.e. neuromuscular blockade, to attain a target profile. The model is based on the patient's neuromuscular blockade (NMB) response to the initial bolus only, overcoming the need for information on the patient's weight, age, height and Lean Body Mass usually associated to pharmacokinetic and pharmacodynamic models. To achieve this, a statistical analysis of the response of the patient to the initial bolus is carried out and a set of variables is established as predictors of the maintenance dose. The prediction is accomplished using Classification and Regression Trees, CART, which is a supervised learning method. Simulated data from a stochastic model for the NMB induced by atracurium is used as training set. All the 5000 doses predicted by the model lead to NMB level between 5% and 10%, which supports the proposed predictive model since it is clinically required that the steady state NMB level lies between this two values. The methodology is applied both to simulated and to clinical data sets and is found appropriate for online dose prediction.

2022

Statistical education and official statistics - training future data scientists

Authors
Silva, ME; Campos, P;

Publication
Proceedings of the IASE 2021 Satellite Conference

Abstract
EMOS (The European Master in Official Statistics) was set up to strengthen the collaboration within academia and producers of official statistics and help develop professionals able to work with European official data at different levels in the fast-changing production system of the 21st century. In this paper we address the need for training in Official Statistics, particularly in current times, where new skill sets and competencies are necessary. In particular, the needs for new data sources currently used by national statistical systems require the development of new methodologies. For that purpose, we do a matching between National Statistical Offices (NSO) needs and the offer from universities.

2022

Comparing Lexical and Usage Frequencies of Palatal Segments in Portuguese

Authors
Trigo, L; Silva, C;

Publication
COMPUTATIONAL PROCESSING OF THE PORTUGUESE LANGUAGE, PROPOR 2022

Abstract
Palatal consonants in Portuguese are considered complex or marked segments because they are inherently heavy and restricted in terms of their distribution, in relation to other consonants. Moreover, they appear to display differences between themselves, as first language acquisition and creoles' adaptation suggest that /L/ is more complex than /n/. The arguments for complexity are endorsed by some qualitative studies but are still lacking quantitative support. This paper aims at analyzing the phonological restrictiveness of these consonants by comparing their actual frequency in several different corpora, reporting both lexical entries and usage in discourse. In addition to their context-free frequency, we control for their word position and phonetic adjacency. We find that palatals are less frequent than other consonants. However, relative to each other, they do not display proportional lexical and usage frequencies. These results shed new light not only on the representation of /n/ and /L/ but also on the relation between frequency and markedness in language studies.

2022

Exploring consonant frequency in Sri Lanka Portuguese

Authors
Silva, C; Trigo, L;

Publication
Proceedings of the Second Workshop on Digital Humanities and Natural Language Processing (2nd DHandNLP 2022) co-located with International Conference on the Computational Processing of Portuguese (PROPOR 2022), Virtual Event, Fortaleza, Brazil, 21st March, 2022.

Abstract
Although phoneme selection is a well-studied subject in contact linguistics, phoneme integration is mostly unexplored. This study aims at assessing phoneme integration by measuring consonant frequency in Sri Lanka Portuguese and Portuguese. For that, we select two large lexical corpora and, take several preparation steps to make the data uniform, consistent and reusable. In terms of integration, we find that the more unconstrained a consonant is concerning its phonotactic patterns, the more frequent it is. We also find that being coronal has a positive impact on integration, whereas being palatal has a negative impact. Moreover, we find that in spite of the apparently random changes in the consonant frequency, consonant classes are robustly transmitted from the lexifier to this creole. Copyright © 2022 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).

2022

Predicting Argument Density from Multiple Annotations

Authors
Rocha, G; Leite, B; Trigo, L; Cardoso, HL; Sousa-Silva, R; Carvalho, P; Martins, B; Won, M;

Publication
NATURAL LANGUAGE PROCESSING AND INFORMATION SYSTEMS (NLDB 2022)

Abstract
Annotating a corpus with argument structures is a complex task, and it is even more challenging when addressing text genres where argumentative discourse markers do not abound. We explore a corpus of opinion articles annotated by multiple annotators, providing diverse perspectives of the argumentative content therein. New annotation aggregation methods are explored, diverging from the traditional ones that try to minimize presumed errors from annotator disagreement. The impact of our methods is assessed for the task of argument density prediction, seen as an initial step in the argument mining pipeline. We evaluate and compare models trained for this regression task in different generated datasets, considering their prediction error and also from a ranking perspective. Results confirm the expectation that addressing argument density from a ranking perspective is more promising than looking at the problem as a mere regression task. We also show that probabilistic aggregation, which weighs tokens by considering all annotators, is a more interesting approach, achieving encouraging results as it accommodates different annotator perspectives. The code and models are publicly available at https://github.com/DARGMINTS/argument density.

2022

Annotating Arguments in a Corpus of Opinion Articles

Authors
Rocha, G; Trigo, L; Cardoso, HL; Sousa-Silva, R; Carvalho, P; Martins, B; Won, M;

Publication
LREC 2022: THIRTEEN INTERNATIONAL CONFERENCE ON LANGUAGE RESOURCES AND EVALUATION

Abstract
Interest in argument mining has resulted in an increasing number of argument annotated corpora. However, most focus on English texts with explicit argumentative discourse markers, such as persuasive essays or legal documents. Conversely, we report on the first extensive and consolidated Portuguese argument annotation project focused on opinion articles. We briefly describe the annotation guidelines based on a multi-layered process and analyze the manual annotations produced, highlighting the main challenges of this textual genre. We then conduct a comprehensive inter-annotator agreement analysis, including argumentative discourse units, their classes and relations, and resulting graphs. This analysis reveals that each of these aspects tackles very different kinds of challenges. We observe differences in annotator profiles, motivating our aim of producing a non-aggregated corpus containing the insights of every annotator. We note that the interpretation and identification of token-level arguments is challenging; nevertheless, tasks that focus on higher-level components of the argument structure can obtain considerable agreement. We lay down perspectives on corpus usage, exploiting its multi-faceted nature.

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