Social distancing strategies against disease spreading

The recurrent infectious diseases and their increasing impact on the society has promoted the study of strategies to slow down the epidemic spreading. In this review we outline the applications of percolation theory to describe strategies against epidemic spreading on complex networks. We give a general outlook of the relation between link percolation and the susceptible-infected-recovered model, and introduce the node void percolation process to describe the dilution of the network composed by healthy individual, $i.e$, the network that sustain the functionality of a society. Then, we survey two strategies: the quenched disorder strategy where an heterogeneous distribution of contact intensities is induced in society, and the intermittent social distancing strategy where health individuals are persuaded to avoid contact with their neighbors for intermittent periods of time. Using percolation tools, we show that both strategies may halt the epidemic spreading. Finally, we discuss the role of the transmissibility, $i.e$, the effective probability to transmit a disease, on the performance of the strategies to slow down the epidemic spreading.Comment: to be published in "Perspectives and Challenges in Statistical Physics and Complex Systems for the Next Decade", Word Scientific Pres

Effect of degree correlations above the first shell on the percolation transition

The use of degree-degree correlations to model realistic networks which are characterized by their Pearson's coefficient, has become widespread. However the effect on how different correlation algorithms produce different results on processes on top of them, has not yet been discussed. In this letter, using different correlation algorithms to generate assortative networks, we show that for very assortative networks the behavior of the main observables in percolation processes depends on the algorithm used to build the network. The different alghoritms used here introduce different inner structures that are missed in Pearson's coefficient. We explain the different behaviors through a generalization of Pearson's coefficient that allows to study the correlations at chemical distances l from a root node. We apply our findings to real networks.Comment: In press EP

Finite-Size-Scaling at the Jamming Transition: Corrections to Scaling and the Correlation Length Critical Exponent

We carry out a finite size scaling analysis of the jamming transition in frictionless bi-disperse soft core disks in two dimensions. We consider two different jamming protocols: (i) quench from random initial positions, and (ii) quasistatic shearing. By considering the fraction of jammed states as a function of packing fraction for systems with different numbers of particles, we determine the spatial correlation length critical exponent $\nu\approx 1$, and show that corrections to scaling are crucial for analyzing the data. We show that earlier numerical results yielding $\nu<1$ are due to the improper neglect of these corrections.Comment: 5 pages, 4 figures -- slightly revised version as accepted for Phys. Rev. E Rapid Communication

Different Harvest Schedules to Prepare Deferred Forage from C4 Grasses in Córdoba, Argentina

From 1995 until 1999 a trial was done in the fields of the Universidad Nacional de Córdoba with four C4 forage grasses. These fields lie in the subtropical and semiarid region of Argentina. This research aimed to identify forage species that could be used as deferred forage for the drier and cooler winter season. Four species of C4 grasses were used: Rhodesgrass (Chloris gayana Kunth), Gatton (Panicum maximum), coloratum (Panicum coloratum) and digitgrass (Digitaria eriantha), respectively. Two growing periods were used: full season growth (FS) and half season regrowth (HS), in both cases the deferred forage was harvested three times: at the beginning, in the middle and at the end of the winter. This paper foccuses DM yields in kg/hectare (DM) and percentage of crude protein (CP). The HS yields less but shows better CP than the FS, therefore it may be a better forage in winter. Coloratum and digigrass seems to give better deferred forage than the other species

NFPA Fluid Powered Vehicle Challenge 2023

This report includes the design process undergone by Team Shifty in designing a vehicle for the NFPA’s Fluid Powered Vehicle challenge. The report covers the background of the competition, research done by the team, engineering specifications for the design, preliminary and final designs, the manufacturing plan and process, project management details, and several recommendations for future teams participating in the challenge. The National Fluid Power Association, NFPA, is a trade association with the goal of connecting fluid power companies and advancing fluid power. With the goal of advancement in mind, NFPA hosts an annual Fluid Powered Vehicle Challenge (FPVC). Since before the NFPA took over this challenge, Cal Poly has produced a team to compete. Team Shifty completed research into past Cal Poly teams as well as other competing university teams to define the engineering specifications for the new vehicle and decide the design directions. The final design includes a new frame to address issues with the last teams frame, a new hydraulic circuit design and selection of new components to improve the circuits performance in the FPVC events and reduce losses, and the addition of gear shifting to the vehicle. With respect to hydraulics, a new manifold was sourced to accommodate the simplified fluid circuit, along with a larger motor to allow the vehicle to operate at higher torque. The prior team’s pneumatic system was completely replaced by a pneumatic front gear shifting system. The electronics implemented was the same system as the previous year, including an STM microcontroller, Nextion touch screen display, and Hydraforce valve operator with only two solenoid valves. Working together, these components allowed the rider to toggle between three unique drive modes, including: direct, regen, and sprint. To produce a functional vehicle, research and planning was put into manufacturing and assembly processes as detailed in the manufacturing plan. The final product failed to perform as proposed in Team Shifty’s Scope of Work, as the vehicle’s rear chain consistently fell off during operation at the competition. This resulted in the vehicle not placing during a few of the challenges, including the Sprint and Endurance races. The cause of this failure was a function of the frame flexing under dynamic loading due to insufficient torsional stiffness, as well as the rear chain being too small to handle the large output torque of the upsized rear motor

Epidemics in partially overlapped multiplex networks

Many real networks exhibit a layered structure in which links in each layer reflect the function of nodes on different environments. These multiple types of links are usually represented by a multiplex network in which each layer has a different topology. In real-world networks, however, not all nodes are present on every layer. To generate a more realistic scenario, we use a generalized multiplex network and assume that only a fraction $q$ of the nodes are shared by the layers. We develop a theoretical framework for a branching process to describe the spread of an epidemic on these partially overlapped multiplex networks. This allows us to obtain the fraction of infected individuals as a function of the effective probability that the disease will be transmitted $T$. We also theoretically determine the dependence of the epidemic threshold on the fraction $q > 0$ of shared nodes in a system composed of two layers. We find that in the limit of $q \to 0$ the threshold is dominated by the layer with the smaller isolated threshold. Although a system of two completely isolated networks is nearly indistinguishable from a system of two networks that share just a few nodes, we find that the presence of these few shared nodes causes the epidemic threshold of the isolated network with the lower propagating capacity to change discontinuously and to acquire the threshold of the other network.Comment: 13 pages, 4 figure