arXiv subjects

Valentina Marin

Publications and source records attributed to Valentina Marin.

5 recordsLinked to original sources

arXiv2026

Conflict, mobility and fragmentation in the African interurban network

Roads make regional integration possible, but they also concentrate risk. When violence reaches a corridor that carries regional movement, the consequences can extend beyond the attacked place. We study this problem in Africa by combining interurban road data, georeferenced conflict events, and bilateral migration flows. Using a Hawkes-style self-exciting memory kernel, we estimate accumulated conflict intensity near roads from 2019 to 2022, and we route modelled movement between cities along the road network. As an empirical check on these modelled corridor flows, we show that country pairs connected by routes with higher accumulated conflict have lower bilateral migration. The association remains negative across alternative assumptions about spatial decay and is strongest for paths that cross regions, consistent with a corridor-deterrence channel rather than only displacement from violent places. We then use cascade and percolation simulations to examine how local disruptions propagate through the road network. Most simulated disruptions isolate relatively small populations, but 18.6% isolate more than one million people, and the largest isolates 13.3 million. Removing roads in order of conflict intensity reveals a tipping point, at which the giant connected component falls from 85% to 39% of the network. Our results identify the roads where violence most threatens regional integration and show how past conflict, mobility, and network structure combine to create persistent corridor vulnerability.

physics.soc-ph↗

arXiv2025

Multiscalarity in Socio-Spatial Segregation: An Information-Theoretic Framework

We present a novel analytical framework to examine socio-spatial segregation across multiple spatial scales, explicitly leveraging information theory and percolation theory. This framework emphasizes the interplay between regional connectivity and population distribution, which are critical for understanding how spatial inequalities arise and persist in urban regions. Employing the Generalised Jensen-Shannon Divergence (GJSD), this method identifies regions characterized by significant segregation and low connectivity, providing actionable insights for targeted urban interventions. Using Ecuador as a case study, we demonstrate how segregation patterns manifest differently at city, regional, and national scales, underscoring the critical role of multiscalarity in understanding urban inequalities and guiding scale-sensitive policies. This approach not only advances the methodology for studying socio-spatial segregation but also contributes to the broader field by highlighting the importance of considering multiscalar perspectives and connectivity in urban systems.

physics.soc-ph↗

arXiv2023

Modelling the multi-scalar effect of commuting on exposure to diversity

Urban systems are primarily relational. The uneven intensities and distribution of flows between systems of cities results in hierarchically organised complex networks of urban exchange. Distinct urban spatial structures reflect the diversity of functional and social patterns which vary or remain constant across multiple scales. In this work, we examine the impact of commuting on the potential accessibility to spatial and social diversity, and the scalar relations that may exist. We first define relational scales by conducting a process of percolation on the commuting network, as a hierarchical clustering algorithm. This gives rise to a nested structure of urban clusters based on flow connectivity. For each cluster at each scale, we compute measures of commuting structural and social diversity by examining the spatial distribution of origin-destination pairs, and the distribution of workers' skills and occupations. To do this, we make use of global entropy measures allowing us to quantitatively analyse the reachable diversity across scales. Applying this methodology to Chile, we observe that the hierarchical accessibility to the wider system of cities and the patterns of spatial interaction, significantly influence the degree of exposure to diversity within urban systems. This framework examines connectivity-based diversity at multiple scales, and allows for the classification of cities and systems of cities according to the spatial and social dimensions of commuting dispersion. Such insights could contribute to the planning of infrastructural projects connecting the urban system at different scales, while also guiding a strategic relocation and redistribution of economic activities at regional levels.

physics.soc-ph↗

arXiv2023

The scalar mismatch of regional governance: a comparative analysis of hierarchical structures

Self-organisation in territories leads to the emergence of patterns in urban systems that shape the interactions between cities, resulting in a hierarchical organisation. Governance follows as well a hierarchical structure, breaking the territory into smaller units for its management. The possible mismatch between these two organisations may lead to a range of problems, ranging from inefficiencies to insufficient and uneven distribution of resources. This paper seeks to develop a methodology to explore and quantify the correspondence between the hierarchical organisation given by the structure of governance and that given by the structure of the urban systems being governed, where Chile is used as case study. The urban hierarchical structure is defined according to the connectivity of the system given by the road network. This is extracted through a clustering algorithm defined as a percolation process on the street network, giving rise to urban clusters at different scales. These are then compared to the spatial scales of the administrative system. This is achieved by computing cophenetic distance on the dendrograms, by looking at the different clustering membership using Jaccard similarity, and by analysing the topological diversity defined as the structural entropy. The results show that the urban sub-national structures present high heterogeneity, while the administrative system is highly homogeneous, replicating the same structure of organisation across the national territory. Such contrasting organisational structures present administrative challenges that can give rise to poor decision-making processes and mismanagement, impairing the efficient functioning of systems. Our results can help address these challenges, informing how to rebalance such mismatches through planning and political strategies that consider the complex interdependencies of territories across scales.

physics.soc-ph↗

arXiv2021

Uncovering structural diversity in commuting networks. Global and local entropy

In this paper we revisit the concept of mobility entropy. Over time, the structure of spatial interactions among urban centres tends to become more complex and evolves from centralised models to more scattered origin and destination patterns. Entropy measures can be used to explore this complexity, and to quantify the degree of structural diversity of in- and out-flows at different scales and across the system. We use toy models of commuting networks to examine global and local measures, allowing the comparison to occur between different parts of the system. We show that entropy at the link and node level give different insights on the characteristics of the systems, enabling us to identify employment hubs and interdependencies between and within different parts of the system. We discuss how these can be used to inform planning and policy decisions oriented towards decentralisation and resilience.

physics.soc-ph↗