Search Results for author: Dimitris Spathis

Found 30 papers, 13 papers with code

PaPaGei: Open Foundation Models for Optical Physiological Signals

1 code implementation27 Oct 2024 Arvind Pillai, Dimitris Spathis, Fahim Kawsar, Mohammad Malekzadeh

PaPaGei is more data- and parameter-efficient than other foundation models or methods, as it outperforms 70x larger models.

Contrastive Learning Domain Generalization +3

StatioCL: Contrastive Learning for Time Series via Non-Stationary and Temporal Contrast

1 code implementation14 Oct 2024 Yu Wu, Ting Dang, Dimitris Spathis, Hong Jia, Cecilia Mascolo

However, existing CL methods often introduce false negative pairs (FNPs) by neglecting inherent characteristics and then randomly selecting distinct segments as dissimilar pairs, leading to erroneous representation learning, reduced model performance, and overall inefficiency.

Contrastive Learning Representation Learning +2

Using Self-supervised Learning Can Improve Model Fairness

1 code implementation4 Jun 2024 Sofia Yfantidou, Dimitris Spathis, Marios Constantinides, Athena Vakali, Daniele Quercia, Fahim Kawsar

Self-supervised learning (SSL) has become the de facto training paradigm of large models, where pre-training is followed by supervised fine-tuning using domain-specific data and labels.

Fairness Self-Supervised Learning

Learning under Label Noise through Few-Shot Human-in-the-Loop Refinement

no code implementations25 Jan 2024 Aaqib Saeed, Dimitris Spathis, JungWoo Oh, Edward Choi, Ali Etemad

We show that FHLR achieves significantly better performance when learning from noisy labels and achieves state-of-the-art by a large margin, with up to 19% accuracy improvement under symmetric and asymmetric noise.

Balancing Continual Learning and Fine-tuning for Human Activity Recognition

no code implementations4 Jan 2024 Chi Ian Tang, Lorena Qendro, Dimitris Spathis, Fahim Kawsar, Akhil Mathur, Cecilia Mascolo

These schemes re-purpose contrastive learning for knowledge retention and, Kaizen combines that with self-training in a unified scheme that can leverage unlabelled and labelled data for continual learning.

Continual Learning Continual Self-Supervised Learning +4

Evaluating Fairness in Self-supervised and Supervised Models for Sequential Data

no code implementations3 Jan 2024 Sofia Yfantidou, Dimitris Spathis, Marios Constantinides, Athena Vakali, Daniele Quercia, Fahim Kawsar

Self-supervised learning (SSL) has become the de facto training paradigm of large models where pre-training is followed by supervised fine-tuning using domain-specific data and labels.

Fairness Self-Supervised Learning

FairComp: Workshop on Fairness and Robustness in Machine Learning for Ubiquitous Computing

no code implementations22 Sep 2023 Sofia Yfantidou, Dimitris Spathis, Marios Constantinides, Tong Xia, Niels van Berkel

From a social perspective, we will examine the relationship between fairness and UbiComp research and identify pathways to ensure that ubiquitous technologies do not cause harm or infringe on individual rights.

Fairness

The first step is the hardest: Pitfalls of Representing and Tokenizing Temporal Data for Large Language Models

no code implementations12 Sep 2023 Dimitris Spathis, Fahim Kawsar

Here, we discuss recent works that employ LLMs for human-centric tasks such as in mobile health sensing and present a case study showing that popular LLMs tokenize temporal data incorrectly.

Kaizen: Practical Self-supervised Continual Learning with Continual Fine-tuning

1 code implementation30 Mar 2023 Chi Ian Tang, Lorena Qendro, Dimitris Spathis, Fahim Kawsar, Cecilia Mascolo, Akhil Mathur

Kaizen is able to balance the trade-off between knowledge retention and learning from new data with an end-to-end model, paving the way for practical deployment of continual learning systems.

Continual Learning Knowledge Distillation +1

Looking for Out-of-Distribution Environments in Multi-center Critical Care Data

no code implementations26 May 2022 Dimitris Spathis, Stephanie L. Hyland

Clinical machine learning models show a significant performance drop when tested in settings not seen during training.

Evaluating Contrastive Learning on Wearable Timeseries for Downstream Clinical Outcomes

no code implementations13 Nov 2021 Kevalee Shah, Dimitris Spathis, Chi Ian Tang, Cecilia Mascolo

Vast quantities of person-generated health data (wearables) are collected but the process of annotating to feed to machine learning models is impractical.

Contrastive Learning Data Augmentation +3

Anticipatory Detection of Compulsive Body-focused Repetitive Behaviors with Wearables

1 code implementation21 Jun 2021 Benjamin Lucas Searle, Dimitris Spathis, Marios Constantinides, Daniele Quercia, Cecilia Mascolo

Body-focused repetitive behaviors (BFRBs), like face-touching or skin-picking, are hand-driven behaviors which can damage one's appearance, if not identified early and treated.

The INTERSPEECH 2021 Computational Paralinguistics Challenge: COVID-19 Cough, COVID-19 Speech, Escalation & Primates

no code implementations24 Feb 2021 Björn W. Schuller, Anton Batliner, Christian Bergler, Cecilia Mascolo, Jing Han, Iulia Lefter, Heysem Kaya, Shahin Amiriparian, Alice Baird, Lukas Stappen, Sandra Ottl, Maurice Gerczuk, Panagiotis Tzirakis, Chloë Brown, Jagmohan Chauhan, Andreas Grammenos, Apinan Hasthanasombat, Dimitris Spathis, Tong Xia, Pietro Cicuta, Leon J. M. Rothkrantz, Joeri Zwerts, Jelle Treep, Casper Kaandorp

The INTERSPEECH 2021 Computational Paralinguistics Challenge addresses four different problems for the first time in a research competition under well-defined conditions: In the COVID-19 Cough and COVID-19 Speech Sub-Challenges, a binary classification on COVID-19 infection has to be made based on coughing sounds and speech; in the Escalation SubChallenge, a three-way assessment of the level of escalation in a dialogue is featured; and in the Primates Sub-Challenge, four species vs background need to be classified.

Binary Classification Representation Learning

Exploring Contrastive Learning in Human Activity Recognition for Healthcare

1 code implementation23 Nov 2020 Chi Ian Tang, Ignacio Perez-Pozuelo, Dimitris Spathis, Cecilia Mascolo

Human Activity Recognition (HAR) constitutes one of the most important tasks for wearable and mobile sensing given its implications in human well-being and health monitoring.

Contrastive Learning Human Activity Recognition

Self-supervised transfer learning of physiological representations from free-living wearable data

1 code implementation18 Nov 2020 Dimitris Spathis, Ignacio Perez-Pozuelo, Soren Brage, Nicholas J. Wareham, Cecilia Mascolo

Our contributions are two-fold: i) the pre-training task creates a model that can accurately forecast HR based only on cheap activity sensors, and ii) we leverage the information captured through this task by proposing a simple method to aggregate the learnt latent representations (embeddings) from the window-level to user-level.

Human Activity Recognition Representation Learning +1

Learning Generalizable Physiological Representations from Large-scale Wearable Data

2 code implementations9 Nov 2020 Dimitris Spathis, Ignacio Perez-Pozuelo, Soren Brage, Nicholas J. Wareham, Cecilia Mascolo

To date, research on sensor-equipped mobile devices has primarily focused on the purely supervised task of human activity recognition (walking, running, etc), demonstrating limited success in inferring high-level health outcomes from low-level signals, such as acceleration.

Human Activity Recognition Representation Learning +1

Exploring Automatic Diagnosis of COVID-19 from Crowdsourced Respiratory Sound Data

4 code implementations10 Jun 2020 Chloë Brown, Jagmohan Chauhan, Andreas Grammenos, Jing Han, Apinan Hasthanasombat, Dimitris Spathis, Tong Xia, Pietro Cicuta, Cecilia Mascolo

This work opens the door to further investigation of how automatically analysed respiratory patterns could be used as pre-screening signals to aid COVID-19 diagnosis.

BIG-bench Machine Learning COVID-19 Diagnosis

Interactive dimensionality reduction using similarity projections

no code implementations13 Nov 2018 Dimitris Spathis, Nikolaos Passalis, Anastasios Tefas

In order to visualize that data in 2D or 3D, usually Dimensionality Reduction (DR) techniques are employed.

Clustering Dimensionality Reduction +2

Photo-Quality Evaluation based on Computational Aesthetics: Review of Feature Extraction Techniques

no code implementations19 Dec 2016 Dimitris Spathis

Researchers try to model the aesthetic quality of photographs into low and high- level features, drawing inspiration from art theory, psychology and marketing.

BIG-bench Machine Learning Marketing

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