Recurrent host mobility in spatial epidemics: beyond reaction-diffusion

Human mobility is a key factor in spatial disease dynamics and related phenomena. In computational models host mobility is typically modelled by diffusion in space or on metapolulation networks. Alternatively, an effective force of infection across distance has been introduced to capture spatial dispersal implicitly. Both approaches do not account for important aspects of natural human mobility, diffusion does not capture the high degree of predictability in natural human mobility patters, e.g. the high percentage of return movements to individuals' base location, the effective force of infection approach assumes immediate equilibrium with respect to dispersal. These conditions are typically not met in natural scenarios. We investigate an epidemiological model that explicitly captures natural individual mobility patterns. We systematically investigate generic dynamical features of the model on regular lattices as well as metapopulation networks and show that generally the model exhibits significant dynamical differences in comparison to ordinary diffusion and effective force of infection models. For instance, the natural human mobility model exhibits a saturation of wave front speeds and a novel type of invasion threshold that is a function of the return rate in mobility patterns. In the light of these new findings and with the availability of precise and pervasive data on human mobility our approach provides a framework for a more sophisticated modeling of spatial disease dynamics

Thermodynamically Consistent Diffuse Interface Models for Incompressible Two-Phase Flows with Different Densities

A new diffuse interface model for a two-phase flow of two incompressible fluids with different densities is introduced using methods from rational continuum mechanics. The model fulfills local and global dissipation inequalities and is also generalized to situations with a soluble species. Using the method of matched asymptotic expansions we derive various sharp interface models in the limit when the interfacial thickness tends to zero. Depending on the scaling of the mobility in the diffusion equation we either derive classical sharp interface models or models where bulk or surface diffusion is possible in the limit. In the two latter cases the classical Gibbs-Thomson equation has to be modified to include kinetic terms. Finally, we show that all sharp interface models fulfill natural energy inequalities.Comment: 34 page

Measuring Sustainability of Kampong Tudong Riverside Settlements Using Urban Modeling Interface Simulation

Coastal settlements are the most vulnerable area to climate change, which has had an increasing impact on natural changes and human life in recent years. Therefore, sustainable riverside settlement models need to be developed by maximizing welfare with minimal environmental damage through modeling simulations that can help understand, compare and evaluate buildings and settlements. Simulation of Kampong Tudong on the banks of Kapuas River used Urban Modeling Interface to analyze the floor area ratio, daylighting, operational energy, and mobility. The simulation results show values of 0.21 on Floor Area Ratio, 30% on average natural resources for building daylighting, 86 kWh/m2year on operational energy, and 66 on mobility. Meanwhile, the efficient standard values are <3.2 on FAR, 55% on average daylighting, 10.08-30 kWh/m2.year on operational energy, and 90-100 on mobility. Existing simulation values indicate that these values can still be improved and maximized further for the sustainability of the riverside settlements

Symmetric tensor gauge theories on curved spaces

Fractons and other subdimensional particles are an exotic class of emergent quasi-particle excitations with severely restricted mobility. A wide class of models featuring these quasi-particles have a natural description in the language of symmetric tensor gauge theories, which feature conservation laws restricting the motion of particles to lower-dimensional sub-spaces, such as lines or points. In this work, we investigate the fate of symmetric tensor gauge theories in the presence of spatial curvature. We find that weak curvature can induce small (exponentially suppressed) violations on the mobility restrictions of charges, leaving a sense of asymptotic fractonic/sub-dimensional behavior on generic manifolds. Nevertheless, we show that certain symmetric tensor gauge theories maintain sharp mobility restrictions and gauge invariance on certain special curved spaces, such as Einstein manifolds or spaces of constant curvature

The Effect of Pok\'emon Go on The Pulse of the City: A Natural Experiment

Pok\'emon Go, a location-based game that uses augmented reality techniques, received unprecedented media coverage due to claims that it allowed for greater access to public spaces, increasing the number of people out on the streets, and generally improving health, social, and security indices. However, the true impact of Pok\'emon Go on people's mobility patterns in a city is still largely unknown. In this paper, we perform a natural experiment using data from mobile phone networks to evaluate the effect of Pok\'emon Go on the pulse of a big city: Santiago, capital of Chile. We found significant effects of the game on the floating population of Santiago compared to movement prior to the game's release in August 2016: in the following week, up to 13.8\% more people spent time outside at certain times of the day, even if they do not seem to go out of their usual way. These effects were found by performing regressions using count models over the states of the cellphone network during each day under study. The models used controlled for land use, daily patterns, and points of interest in the city. Our results indicate that, on business days, there are more people on the street at commuting times, meaning that people did not change their daily routines but slightly adapted them to play the game. Conversely, on Saturday and Sunday night, people indeed went out to play, but favored places close to where they live. Even if the statistical effects of the game do not reflect the massive change in mobility behavior portrayed by the media, at least in terms of expanse, they do show how "the street" may become a new place of leisure. This change should have an impact on long-term infrastructure investment by city officials, and on the drafting of public policies aimed at stimulating pedestrian traffic.Comment: 23 pages, 7 figures. Published at EPJ Data Scienc

Effects of mobility on ordering dynamics

Models of ordering dynamics allow us to understand natural systems in which an initially disordered population homogenizes some traits via local interactions. The simplest of these models, with wide applications ranging from evolutionary to social dynamics, are the Voter and Moran processes, usually defined in terms of static or randomly mixed individuals that interact with a neighbor to copy or modify a discrete trait. Here we study the effects of diffusion in Voter/Moran processes by proposing a generalization of ordering dynamics in a metapopulation framework, in which individuals are endowed with mobility and diffuse through a spatial structure represented as a graph of patches upon which interactions take place. We show that diffusion dramatically affects the time to reach the homogeneous state, independently of the underlying network's topology, while the final consensus emerges through different local/global mechanisms, depending on the mobility strength. Our results highlight the crucial role played by mobility in ordering processes and set up a general framework that allows its effect to be studied on a large class of models, with implications in the understanding of evolutionary and social phenomena

The Current Account And The Intertemporal Budget Constraint: Evidence From G-7 Countries

A random coefficients, error-correction model of saving-investment behaviour, which is consistent with intertemporal open-economy models, is estimated for G-7 countries to infer about the current account, capital mobility and the relevance of intertemporal budget constraints in such model. The error-correction mechanism is especially suited here since it is able to integrate short run dynamics with long run behaviour, while the random coefficients approach is a natural specification for accommodating inter-country differences. If saving-investment correlations measure capital mobility, a positive correlation would mean that a country’s growth prospects would be constrained by its saving, government deficits would crowd out private investment and, at a broader level, good investment opportunities might have to be foregone unless the required resources were obtained through a sacrifice in current consumption. On the other hand, those correlations could also be seen as validating the use of intertemporal budget constraints in open-economy models.