Research Areas

The Rappel Lab at UC San Diego focuses on understanding complex biological systems through the lens of physics. We combine theoretical modeling, computational simulations, and experimental studies to investigate fundamental questions in cell biology and cardiac physiology.

Cell Motility & Chemotaxis

Cell motility is fundamental to many biological processes including wound healing, immune response, and cancer metastasis. We study how cells sense chemical gradients (chemotaxis) and translate these signals into directed movement. Our work combines mathematical modeling with experimental data to understand the signaling networks that enable cells to navigate their environment.

  • Gradient sensing mechanisms
  • Signal transduction networks
  • Mathematical models of cell migration
  • Dictyostelium discoideum studies
Example movie of two-dimensional Ras dynamics: signaling activity changes across the cell over time, illustrating how intracellular patterns can help organize directed motion during chemotaxis.
Cell Motility

Cardiac Dynamics

The heart is an excitable medium where electrical waves coordinate the contraction of millions of cells. We develop computational models to understand how these waves propagate, what causes arrhythmias, and how the heart's geometry affects its electrical behavior. Our work has implications for understanding and treating conditions like atrial fibrillation.

  • Wave propagation modeling
  • Arrhythmia mechanisms
  • Cardiac tissue simulations
  • Atrial fibrillation research
Example movie of intermittent spiral-wave trapping: a rotating wave repeatedly interacts with a local inhomogeneity, showing how tissue structure can anchor and release cardiac electrical activity.
Cardiac Dynamics

Developmental Biology

Embryonic development involves precisely coordinated cell movements and tissue organization. We investigate how physical forces and biochemical signals work together to create complex structures. Our research explores pattern formation, morphogenesis, and the mechanical properties of developing tissues.

  • Morphogenesis
  • Pattern formation
  • Tissue mechanics
  • Cell sorting mechanisms
Example movie of cell sorting in Dictyostelium discoideum: initially mixed cell populations reorganize over time, showing how local interactions and cell motion can drive like cells to cluster and sort.
Dynamic model that describes the trajectory of border cells moving within a realistic Drosophila egg chamber recapitulates experimentally observed trajectories.
Developmental Biology

Computational Methods

We develop and apply computational methods to study biological systems across multiple scales. This includes molecular dynamics simulations, phase-field models, and machine learning approaches for analyzing experimental data. Our methods enable us to bridge the gap between molecular interactions and cellular behavior.

  • Phase-field modeling
  • Multi-scale simulations
  • Data analysis pipelines
  • Machine learning applications
Persistent rotational motion on a patterned surface modeled using a phase field for both the cell and the nucleus.
Two-cell phase-field model

Atrial Fibrillation & Arrhythmia Mapping

Atrial fibrillation is a complex rhythm disorder in which abnormal electrical activity disrupts coordinated cardiac contraction. We combine computational models, signal analysis, and AI-assisted mapping methods to identify organizing patterns in arrhythmic activity and to connect those patterns to underlying tissue structure.

  • Arrhythmia source localization
  • Atrial activation mapping
  • Signal processing and feature extraction
  • AI-assisted rhythm classification
Example movie of atrial fibrillation mapping in a patient with atrial fibrillation. The map shows a clear rotational source and ablation at the site of this source terminated the arrhythmia.
Atrial fibrillation and arrhythmia mapping