Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovering dynamic laws from observations: the case of self-propelled,
  interacting colloids   Active matter spans a wide range of time and length scales, from groups of
cells and synthetic self-propelled particles to schools of fish, flocks of
birds, or even human crowds. The theoretical framework describing these systems
has shown tremendous success at finding universal phenomenology. However,
further progress is often burdened by the difficulty of determining the forces
that control the dynamics of the individual elements within each system.
Accessing this local information is key to understanding the physics dominating
the system and to create the models that can explain the observed collective
phenomena. In this work, we present a machine-learning model, a graph neural
network, that uses the collective movement of the system to learn the active
and two-body forces controlling the individual dynamics of the particles. We
verify our approach using numerical simulations of active brownian particles,
considering different interaction potentials and levels of activity. Finally,
we apply our model to experiments of electrophoretic Janus particles,
extracting the active and two-body forces that control the dynamics of the
colloids. Due to this, we can uncover the physics dominating the behavior of
the system. We extract an active force that depends on the electric field and
also area fraction. We also discover a dependence of the two-body interaction
with the electric field that leads us to propose that the dominant force
between these colloids is a screened electrostatic interaction with a constant
length scale. We expect that this methodology can open a new avenue for the
study and modeling of experimental systems of active particles.

15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci