Albert Alonso

Postdoc, Aalborg University · Spatio-temporal Modelling & Probabilistic Machine Learning

aadlf@cs.aau.dk

Lonso, Alberta

I'm a postdoc at Aalborg University, working on landscape modeling and uncertainty quantification as part of the DK-Future project.

Previously, I was at the IMAGE section at DIKU, working on explainable AI and medical image segmentation.

I did my PhD in Biophysics at the Niels Bohr Institute as part of the Kirkegaard Lab. My dissertation, Mind the Gradient, explored differentiable methods for studying microorganism behavior and optimality in biological systems.

I also build open-source tools, mostly in JAX. Always open to ideas and collaborations.

Google Scholar | GitHub | Looking for Lonso, Alberta? Here you go.

Research

Peer-reviewed Papers (Journals & Conferences)

rNCA: Self-Repairing Segmentation Masks
Preprint OpenReview Code
rNCA self-repairing segmentation Biological organisms have developed extraordinary capabilities to fix broken structures. We exploit that and construct a cellular-automata network to fix common issues on pixel-wise segmentation masks, resulting in a surprisingly effective method that efficiently repairs topological artifacts in medical segmentation models.
Extremal Contours: Gradient-driven contours for compact visual attribution
Preprint OpenReview Code
Extremal contours We introduce a new explainability mask where a closed contour 'relaxes' on top of the object that the Neural Network is basing its decision on. The cool part is that we move the contour by propagating the gradients through the network and the masking process. Very simple and elegant.
Spline refinement with differentiable rendering
Paper Preprint Code
Sometimes predicted centerlines look slightly off. We introduce a training-free differentiable rendering approach to spline refinement, achieving both high reliability and sub-pixel accuracy. It serves as a drop-in replacement for the popular active contour model.
Adaptive Node Positioning in Biological Transport Networks
Paper Preprint Code
Adaptive nodes When the hydrodynamic graph model accounts for the energy cost of delivery from node to area, we can apply automatic differentiation to study optimal node positions. Curiously, when the domain is irregular (as in leaves), nodes distribute themselves to maximize efficiency.
Local Clustering and Global Spreading of Receptors for Optimal Spatial Gradient Sensing
Paper Preprint Code
Receptor clustering Tiny cells have a hard time sensing their environment due to physical limits. We present a theoretical model exploring how receptors should be placed for optimal information processing. Results show clustering in high-curvature membrane regions, aligning with real-cell observations.
Persistent pseudopod splitting is an effective chemotaxis strategy in shallow gradients
Paper Preprint Code
Pseudopod splitting Decision making is hard for microscopic cells, yet essential for survival. We present a minimal model providing quantitative understanding of how cells use pseudopod splitting to achieve high-performance chemotaxis with minimal regulation—mechanical intelligence.
Irreversibility in Non-reciprocal Chaotic Systems
Paper Preprint
A stochastic-thermodynamic framework analyzing the relationship between irreversibility and dynamical behavior in high-dimensional chaotic systems.
Learning optimal integration of spatial and temporal information in noisy chemotaxis
Paper Preprint Code
ChemoXRL Two main chemotaxis strategies exist in nature: temporal (for small cells) and spatial (for larger cells). We show the transition is continuous and a combined strategy outperforms constrained variants.
Fast detection of slender bodies in high-density microscopy data
Paper Preprint Code
DeepTangle An end-to-end deep learning approach for extracting precise shape trajectories of motile, overlapping slender bodies in high-density microscopy, applied to swimming nematodes.

PhD Thesis

Mind The Gradient: Differentiable Computational Methods in Microorganism Behaviour Studies
Thesis
Uses differentiable programming techniques to develop computational methods and mathematical models exploring navigation, sensory integration, and behavioral adaptations under physical constraints of the microscopic scale.

Software

  • Bayex – Bayesian Optimization in JAX stars
  • PCAx – Differentiable PCA in JAX stars
  • t-SNEx – Minimal t-SNE in JAX stars
  • BoundVor – Bounded Voronoi Tessellation stars
  • Notata – Scientific Logging stars

See my GitHub for more details.