arXiv subjects

Raissa D'Souza

Publications and source records attributed to Raissa D'Souza.

5 recordsLinked to original sources

arXiv2026

From risk to flourishing: Seeds for responding to a complex world

Flourishing is the actualization of all beings toward their good -- not only individually but collectively, answering the question of `how do we live well with and for each other?'. In science as in society, the tendency to reduce, segregate, specialize, and settle has precluded embracing the concept of flourishing as a guiding principle. We aim to identify an approach to risk science research that promotes the flourishing of socio-ecological-technological systems (SETS). We discuss the normative role of an orientation toward flourishing for the field of risk science. We explore the possibility that (risk) science could be done in a way that is capable of pointing society toward a different future, one more resilient and more capable of flourishing. Our exploration mirrors the conversational nature of flourishing itself: examine ideologies traditionally believed to be rigidly in opposition and consider what emerges in the space(s) and conversation between them. We call this a dialectical approach. Within this paradigm grounded in conversation, pluralism, and pragmatism, we revisit three longstanding tensions in risk science: physical$|$social, determinism$|$uncertainty, contextuality$|$generality. Although these tensions are not new, revisiting them together through the lens of complexity science, and with explicit attention to the normative commitments that shape risk research, reveals underexplored possibilities for the field. Examining them in conversation with the other allows us to explore the provisional seeds for what might be termed complex risk science: interdependence, responsivity, participation, pluralism, openness, and ongoingness. Enacting the dialectical paradigm towards a risk science for a flourishing world will depend on creating collectives toward complex risk science, supporting them with skillfully governed commons, and centering care in our research.

physics.soc-ph↗

arXiv2025

What does the tree of life look like as it grows? Evolution and the multifractality of time

By unifying three foundational principles of modern biology, we develop a mathematical framework to analyze the growing tree of life. Contrary to the static case, where the analogy between phylogenetic trees and the tree that grows in soil is drawn, our framework shows that the living tree of life is analogous to a Cantor dust where each branch is a distinct fractal curve. The system as a whole is therefore multifractal in the sense that it consists of many unique fractals. The three foundational principles for the mathematical framework are that phylogeny is nested, phylogeny is dualistic (i.e., transitive between singularities and populations), and phylogeny is stochastic. Integrating these three principles, we model the dynamic (i.e., living) tree of life as a random iterated function system that generates unique convexly related sequences of branching random variables (visualized in Animation 1). The multifractal nature of this dynamic tree of life implies that, for any two living entities, the time interval from their last common ancestor to the present moment is a distinct fractal curve for each. Thus, the length of a time interval along each distinct branch is unique, so that time is also multifractal and not an ultrametric on the tree of life.

q-bio.PE↗

arXiv2023

Unified framework for hybrid percolation transitions based on microscopic dynamics

A hybrid percolation transition (HPT) exhibits both discontinuity of the order parameter and critical behavior at the transition point. Such dynamic transitions can occur in two ways: by cluster pruning with suppression of loop formation of cut links or by cluster merging with suppression of the creation of large clusters. While the microscopic mechanism of the former is understood in detail, a similar framework is missing for the latter. By studying two distinct cluster merging models, we uncover the universal mechanism of the features of HPT-s at a microscopic level. We find that these features occur in three steps: (i) medium-sized clusters accumulate due to the suppression rule hindering the growth of large clusters, (ii) those medium size clusters eventually merge and a giant cluster increases rapidly, and (iii) the suppression effect becomes obsolete and the kinetics is governed by the Erdős-Rényi type of dynamics. We show that during the second and third period, the growth of the largest component must proceed in the form of a Devil's staircase. We characterize the critical behavior by two sets of exponents associated with the order parameter and cluster size distribution, which are related to each other by a scaling relation. Extensive numerical simulations are carried out to support the theory where a specific method is applied for finite-size scaling analysis to enable handling the large fluctuations of the transition point. Our results provide a unified theoretical framework for the HPT.

cond-mat.stat-mech↗

arXiv2018

Spread, then Target, and Advertise in Waves: Optimal Budget Allocation Across Advertising Channels

We analyze optimal strategies for the allocation of a finite budget that can be invested in different advertising channels over time with the objective of influencing social opinions in a network of individuals. In our analysis, we consider both exogenous influence mechanisms, such as advertising campaigns, as well as endogenous mechanisms of social influence, such as word-of-mouth and peer-pressure, which are modeled using diffusion dynamics. We show that for a broad family of objective functions, the optimal influence strategy at every time uses all channels at either their maximum rate or not at all, i.e., a bang-bang strategy. Furthermore, we prove that the number of switches between these extremes is bounded above by a term that is typically much smaller than the number of agents. This means that the optimal influence strategy is to exert maximum effort in waves for every channel, and then cease effort and let the effects propagate. We also show that, at the beginning of the campaign, the total cost-adjusted reach of an exogenous advertising channel determines its relative value. In contrast, as we approach our investment horizon (e.g., election day), the optimal strategy is to invest in channels able to target individuals instead of broad-reaching channels. We demonstrate that the optimal influence strategies are easily computable in several practical cases, and explicitly characterize the optimal controls for the case of linear objective functions in closed form. Finally, we see that, in the canonical example of designing an election campaign, identifying late-deciders is a critical component in the optimal design.

math.OC↗

arXiv2017

Resilience by Structural Entrenchment: Dynamics of Single-Layer and Multiplex Networks Following Sudden Changes to Tie Costs

We examine a model of network formation in single-layer and multiplex networks in which individuals have positive incentives for social ties, closed triangles, and spillover edges. In particular, we investigate the influence of shocks to the network in which the cost of social ties changes after an initial equilibrium. We highlight the emergence of structural entrenchment: the retention of structural features, such as closed triangles and spillover edges, which are formed under historically different conditions from those currently driving network evolution. This work has broad implications for understanding path dependence in the structure and dynamics of single-layer and multiplex networks.

cs.SI↗