arXiv subjects

Nahuel Zamponi

Publications and source records attributed to Nahuel Zamponi.

4 recordsLinked to original sources

arXiv2025

Behavior of the scaling correlation functions under severe subsampling

Scale-invariance is a ubiquitous observation in the dynamics of large distributed complex systems. The computation of its scaling exponents, which provide clues on its origin, is often hampered by the limited available sampling data, making an appropriate mathematical description a challenge. This work investigates the behavior of correlation functions in fractal systems under conditions of severe subsampling. Analytical and numerical results reveal a striking robustness: the correlation functions continue to capture the expected scaling exponents despite substantial data reduction. This behavior is demonstrated numerically for the random 2-D Cantor set and the Sierpinski gasket, both consistent with exact analytical predictions. Similar robustness is observed in 1-D time series both synthetic and experimental, as well as in high-resolution images of a neuronal structure. Overall, these findings are broadly relevant for the structural characterization of biological systems under realistic sampling constraints.

physics.comp-ph↗

arXiv2022

Scale free density and correlations fluctuations in the dynamics of large microbial ecosystems

Microorganisms self-organize in very large communities exhibiting complex fluctuations. Despite recent advances, still the mechanism by which these systems are able to exhibit large variability at the one hand and dynamical robustness on the other, is not fully explained. With that motivation, here we analyze three aspects of the dynamics of the microbiota and plankton: the density fluctuations, the correlation structure and the avalanching dynamics. In all communities under study we find that the results exhibits scale-free density fluctuations, anomalous variance' scaling, scale-free abundance correlations and stationary scale-free avalanching dynamics. These behaviors, typical in systems exhibiting critical dynamics, suggest criticality as a potential mechanism to explain both the robustness and (paradoxical) high irregularity of processes observed in very large microbial communities.

q-bio.PE↗

arXiv2020

Universal dynamics of mitochondrial networks: a finite-size scaling analysis

A growing body of evidence suggests that the structure of mitochondrial networks is poised near criticality, an intermediate regime lying in between order and disorder. Such description fits well with the idea that biological systems, in general, may benefit from the long-range correlations and large flexibility conferred by a critical regime. Despite the attractiveness of this proposal, a clear understanding of the possible scenarios leading these networks to criticality is still lacking. In this work, we compared the behavior of mitochondrial networks emerging from a dimensionless agent-based (AB) model and a spatially explicit (SE) model, in which nodes are embedded on a 2D lattice. In both scenarios, we described the position of the control parameter at which mitochondrial networks exhibit a dynamical phase transition as well as the size-dependency of several network features. Furthermore, we showed that the mitochondrial networks from mouse embryonic fibroblasts presented similar topologies to the ones generated using the AB model, while their universal behavior is better described by a SE model. Using finite-size scaling analysis conducted on models and empirical data we defined the universality classes they belong and provided the theoretical boundaries for the mechanisms governing mitochondrial network formation. Our findings predict the full repertoire of dynamical behavior expected for real mitochondrial networks under physiological and pathological conditions.

physics.bio-ph↗

arXiv2018

Mitochondrial network complexity emerges from fission/fusion dynamics

Mitochondrial networks exhibit a variety of complex behaviors, including coordinated cell-wide oscillations of energy states as well as a phase transition (depolarization) in response to oxidative stress. Since functional and structural properties are often interwinded, here we characterize the structure of mitochondrial networks in mouse embryonic fibroblasts using network tools and percolation theory. Subsequently we perturbed the system either by promoting the fusion of mitochondrial segments or by inducing mitochondrial fission. Quantitative analysis of mitochondrial clusters revealed that the structural parameters of healthy mitochondria lay in between the extremes of highly fragmented and completely fusioned networks. We confirmed our results by contrasting our emprirical findings with the predictions of a recently described computational model of mitochondrial network emergence based on fission-fusion kinetics. Altogether these results not only offer an objective methodology to parametrize the complexity of this organelle but add weight to the idea that mitochondrial networks behave as critical systems and undergo structural phase transitions.

physics.bio-ph↗