Intro  Research Highlights  Education  Awards  Publications  Work

I work at the intersection of applied and theoretical machine learning for time-series data, with a strong application focus on wearable health biosensors. My goal is to develop self-supervised learning methodologies to be used with foundation models for wearable health sensors.

As a University of Illinois Urbana-Champaign PhD student, I work with Jim Rehg as my advisor and have recieved the NSF Graduate Research Fellowship and Georgia Tech Presidential Fellowship awards. I started my PhD in 2020 with Dr. Rehg at Georgia Tech before transferring to UIUC with him. I expect to graduate in Fall 2026.

This spring, I will be joining the Google Health Research team, researching foundation models for wearable health biosignals. Prior to this, I worked at the Apple Health AI team, researching self-supervised methodologies for a IMU-based motion foundation model.

My previous bioinformatics research was on understanding how the overexpression of the GABA genes affects cancer prognosis. I was advised by Soma Sengupta and Daniel Krummel at UNC Chapel Hill.

---- Recent News: I will be joining the Google Health Research team in December 2024, researching foundation models for wearable health biosignals! ----

---- Webpage Last Updated: 11/03/2024 ----


ICLR 2024
We introduce a novel method of identifying positives and negatives for time-series contrastive learning with Retrieval-Based Reconstruction (REBAR). The REBAR metric predicts mutual class membership of two subsequences, and our contrastive learning approach achieves SOTA performance.
NeurIPS 2022
PulseImpute is the first mHealth pulsative signal imputation challenge which includes realistic missingness models, clinical downstream tasks, and an extensive set of baselines, including an augmented transformer that achieves SOTA performance.

Aug 2020 — Ph.D. in Computer Science
PresentUniversity of Illinois Urbana-Champaign
Advisor: Jim Rehg
Anticipated Graduation: Fall 2026

Aug 2020 — M.S. in Computer Science
May 2023Georgia Institute of Technology
Overall GPA: 4.00/4.00

Aug 2016 — B.S. in Applied Mathematics and Statistics
Dec 2019 B.S. in Biomedical Engineering
Johns Hopkins University
Overall GPA: 3.84/4.00


20242nd Place Poster at the 11th Annual Jump ARCHES Symposium
• Awarded for poster on RelCon: Relative Contrastive Learning for a Motion Foundation Model for Wearable Data.
• Jump ARCHES is a partnership between OSF Healthcare and UIUC that partners teams of clinicians and engineers working together to improve patient outcomes and reduce health care costs.

2022National Science Foundation Graduate Research Fellowship
• Awarded for displaying exemplary levels of research skill and potential
• Press Release: https://grad.gatech.edu/news/49-students-awarded-prestigious-national-science-foundation-graduate-research-fellowship

2020Georgia Tech Presidential Fellowship
• Awarded for displaying exemplary levels of scholarship and innovation

2020Intuitive Surgical Best Project Award
• For "MATHIAS: Modeling A Transferable Histopathological Image Analysis System"
• Press Release: https://www.cs.jhu.edu/2020/01/28/deep-learning-course-prepares-students-for-success-in-ai-careers/

20191st Place in Fall 2019 Johns Hopkins FastForward U Spark Accelerator Competition
• Press Release: https://ventures.jhu.edu/news/bioswift-aquatas-fast-forward-u-accelerator-demo-days/

20191st Place in 2019 ASAIOfyi Student Design Competition
• Press Release: https://www.facebook.com/jhu.admissions/posts/congrats-to-team-bioswift-jhubme-hopkinsengineering/10156494724603946/


Towards Time Series Reasoning with LLMs
Winnie Chow, Lauren Gardiner, Haraldur T Hallgrímsson, Maxwell A. Xu, Shirley You Ren
Oral Presentation at NeurIPS Workshop on Time Series in the Age of Large Models, 2024
Paper

Temporally Multi-Scale Sparse Self-Attention for Physical Activity Data Imputation
Hui Wei, Maxwell A. Xu, Colin Samplawski, Hui Wei, James M. Rehg, Santosh Kumar, Benjamin M. Marlin
Conference on Health, Inference, and Learning (CHIL), 2024
Paper

REBAR: Retrieval-Based Reconstruction For Time-series Contrastive Learning
Maxwell A. Xu, Alexander Moreno, Hui Wei, Benjamin M. Marlin, James M. Rehg
The Twelfth International Conference on Learning Representations (ICLR), 2024
Paper Code Poster

PulseImpute: A Novel Benchmark Task for Pulsative Physiological Signal Imputation
Maxwell A. Xu, Alexander Moreno, Supriya Nagesh, V. Burak Aydemir, David W. Wetter, Santosh Kumar, James M. Rehg
Proceedings of the Neural Information Processing Systems (NeurIPS), 2022.
Paper Project Page Code Poster

Discovering Novel Predictors of Minimally Verbal Outcomes in Autism through Computational Modeling
Maxwell A. Xu, James M. Rehg, Agata Rozga, Jena McDaniel, Paul Yoder, Linda R. Watson, Nancy Brady
INSAR Oral + Press Conference (~ 1% acceptance rate), 2022.
Paper Press Release Video

Efficient Learning and Decoding of the Continuous-Time Hidden Markov Model for Disease Progression Modeling
Yu-Ying Liu, Alexander Moreno, Maxwell A. Xu, Jena McDaniel, Nancy Brady, Agata Rozga, Fuxin Li, Le Song, James M. Rehg
arXiv, 2021.
Paper Code Co-second authors

Impact of Sequencing Radiation Therapy and Immune Checkpoint Inhibitors in the Treatment of Melanoma Brain Metastases
Daniel Pomeranz Krummel, Tahseen H. Nasti, Benjamin Izar, Robert H. Press, Maxwell Xu, Lindsey Lowder, Laura Kallay, Manali Rupji, Havi Rosen, Jing Su, Walter Curran, Jeffrey Olson, Brent Weinberg, Matthew Schniederjan, Stewart Neill, David Lawson, Jeanne Kowalski, Mohammed Khan, Soma Sengupta
International Journal of Radiation Oncology, 2020.
Paper Co-first authors; Co-second authors

Modulating Native GABAA Receptors in Medulloblastoma with Positive Allosteric Benzodiazepine-derivatives Induces Cell Death
Laura Kallay, Havva Keskin, Alexandra Ross, Manali Rupji, Olivia A Moody, Xin Wang, Guanguan Li, Taukir Ahmed, Farjana Rashid, Michael Rajesh Stephen, Kirsten A Cottrill, T Austin Nuckols, Maxwell Xu, Deborah E Martinson, Frank Tranghese, Yanxin Pei, James M Cook, Jeanne Kowalski, Michael D Taylor, Andrew Jenkins, Daniel A Pomeranz Krummel, Soma Sengupta
Journal of Neuro-Oncology, 2019.
Paper


Dec 2024 —Google, Seattle, WA
PresentStudent Researcher, Google Health
• Research on foundation models for wearable health biosignals

Apr 2024 —Apple, Seattle, WA
Sep 2024Research Intern, Health AI
• Spearheaded research efforts on self-supervised learning methods for a health time-series foundation model.
• Collaborated with interdisciplinary team to fuse health-domain knowledge in guiding model development
• Heavily assisted in engineering efforts for machine learning pipeline and infrastructure

Jan 2020 —Systems & Technology Research, Boston, MA
Aug 2020Machine Learning Researcher, Cyber-Physical Systems
• Spearheaded machine learning initiatives within the cybersecurity vulnerability research
• Created a reinforcement learning method for greybox mutation-based fuzzer
• Developed a seq2seq VQ-VAE WaveRNN decoder for unsupervised representation learning of audio

May 2019 —Medtronic, North Haven, CT
Dec 2019AI/Data Science Engineer Contractor, Minimal Invasive Therapies Group
• Developed a tool to predict lung cancer recurrence from clinical big data using machine learning
• Created a computer vision blob detection tool
• Utilized survival analysis with Kaplan-Meier curve visualizations to identify cancer recurrence risk factors

Aug 2018 —BioSwift, Baltimore, MD
Dec 2019Former Chief Executive Officer and Co-Founder
• Designed device to augment dry powder inhalers for usage among pediatric asthmatics
• Secured over $10,000 in funding, from various business and design competitions as well as the Johns Hopkins Student Initiatives Fund
• Press Release: https://www.jhunewsletter.com/article/2019/11/fastforward-u-teams-innovate-with-new-and-old-technologies

Jan 2019 —Johns Hopkins University Department of Computer Science, Baltimore, MD
Jan 2020Teaching Assistant, Data Structures
• Collaborated with team of faculty during weekly meetings and actively contributed to course content
• Worked with students to enhance student understanding of content such as heaps, AVL trees, hashmaps

May 2018 —Centers for Disease Control and Prevention, Atlanta, GA
Aug 2018Biostatistics Intern, Outbreak Surveillance
• Spearheaded a new initiative to utilize whole genome multilocus sequence typing data for detecting disease clusters

Conference Abstracts

EXTH-12. Radiation Enhances Melanoma Response to Immunotherapy and Synergizes with Benzodiazepines to Promote Anti-Tumor Activity
Daniel Pomeranz Krummel, Tahseen H. Nasti, Benjamin Izar, Robert H. Press, Maxwell Xu, Lindsey Lowder, Laura Kallay, Manali Rupji, Havi Rosen, Jing Su, Walter Curran, Jeffrey Olson, Brent Weinberg, Matthew Schniederjan, Stewart Neill, David Lawson, Jeanne Kowalski, Mohammed Khan, Soma Sengupta
Neuro-Oncology 2020. Phoenix, Arizona
Paper Co-first authors; Co-second authors

Abstract 247: Identification of the GABAA Receptor in Melanoma Brain Metastases Patient Tumors and Demonstration that It is a Viable Drug Target using Benzodiazepine-Derivatives
Milota Kaluzova, Tahseen Nasti, Hiao-Rong Chen, Lindsey Lowder, Robert Press, Havi Rosen, Manali Rupji, Laura Kallay, Rikesh Patel, Andre Burnham, Maxwell Xu, Alexandra Ross, Havva Keskin, Erin Connelly, Benjamin Izar, Cory Adamson, Jeffrey Olson, Jing Su, Walter Curran, Ragini Kudchadkar, Matthew Schniederjan, Stewart Neill, David Lawson, Michael Chan, Jeanne Kowalski, Mohammad Khan, Daniel Pomeranz Krummel, Soma Sengupta
AACR Annual Meeting 2019. Atlanta, GA
Paper

Abstract 2623: Modulating Native GABAA Receptors in Medulloblastoma with Positive Allosteric Benzodiazepine-Derivatives Induces Cell Death
Laura Kallay, Havva Keskin, Alexandra Ross, Manali Rupji, Olivia A. Moody, Xin Wang, Guanguan Li, Taukir Ahmed, Farjana Rashid, Michael Rajesh Stephen, Kirsten A. Cottrill, Austin Nuckois, Maxwell Xu, Deborah E. Martinson, Frank Tranghese, Yanxin Pei, James M. Cook, Jeanne Kowalski, Michael D. Taylor, Andrew Jenkins, Daniel Pomeranz Krummel, Soma Sengupta
AACR Annual Meeting 2019. Atlanta, GA
Paper

COMP-22: Large Scale Transcriptomic Analysis of Melanoma Brain Metastases
Jeanne Kowalski, Daniel Pomeranz Krummel, Manali Rupji, Bhakti Dwivedi, Havva Keskin, Laura Kallay, Maxwell Xu, Alexandra Ross, Robert Press, Havi Rosen, Erin Connelly, Rikesh Patel, Benjamin Izar, Cory Adamson, Jeffrey Olson, Jing Su, Ragini Kudchadkar, Matthew Schniederjan, Lindsey Lowder, Stewart Neill, Walter Curran, David Lawson, Michael Chan, Mohammad Khan, Soma Sengupta
Neuro-Oncology 2018. New Orleans, LA
Paper

PDTM-45: Positive Modulation of Native GABAA Receptors in Medulloblastoma Cancer Cells with Benzodiazepines Induces Rapid Mitochondrial Fragmentation and TP53-Dependent, Cell Cycle-Independent Apoptosis
Laura Kallay, Havva Keskin, Alexandra Ross, Olivia Moody, Kirsten Cottrill, Austin Nuckols, Guanguan Li, Taukir Ahmed, Farjana Rashid, Michael Stephen, Maxwell Xu, Deborah Martinson, Tobey Macdonald, Jeanne Kowalski, Xin Wang, Michael Taylor, James Cook, Andrew Jenkins, Daniel Pomeranz Krummel, Soma Sengupta
Neuro-Oncology 2018. New Orleans, LA
Paper

CD131: Large Scale Transcriptomic Analysis of Melanoma Brain Metastases
Jeanne Kowalski, Daniel Pomeranz Krummel, Manali Rupji, Bhakti Dwivedi, Havva Keskin, Laura Kallay, Maxwell Xu, Alexandra Ross, Robert Press, Havi Rosen, Erin Connelly, Rikesh Patel, Benjamin Izar, Cory Adamson, Jeffrey Olson, Jing Su, Ragini Kudchadkar, Matthew Schniederjan, Lindsey Lowder, Stewart Neill, Walter Curran, David Lawson, Michael Chan, Mohammad Khan, Soma Sengupta
Annals of Neurology 2018.
Paper