“Who Has the Power to Adapt?” Frameworks for Resilient Agriculture Must Contend With the Power Dynamics of Land Tenure

This special issue aims to develop how Diversified Farming Systems (DFS) may contribute to adaptive capacity in order to confer resilience to agricultural systems. In this perspective article, I argue that a framework for DFS and adaptive capacity must adequately contend with the role of farmland tenure on the shape of food systems to be both internally coherent and socially redistributive. Yet, both DFS and adaptive capacity scholarship deemphasize or mischaracterize the role of farmland tenure in favor of ecosystem dynamics. In this paper, I bring together lessons from the agrarian change literature and established critiques of resilience thinking to demonstrate core problems with a framework aimed at linking DFS to adaptive capacity without adequately addressing the role of farmland tenure. Namely, applying resilience thinking as a framework to understand food systems change prioritizes concern over final “states” or processes of farming systems and may ignore who has the power to adapt or who derives benefits from adaptation. The critiques of resilience thinking inform that the result of this apolitical elision is (1) entrenchment of neoliberal logics that place responsibility to cultivate adaptation on individual farmers and (2) provisioning of legitimacy for land tenure systems that can most readily adopt DFS, without understanding how well these systems distribute public benefits. Resilience reformers call for ways to include more power aware analysis when applying resilience thinking to complex socio-technical systems. I suggest that centering the role of land tenure into the frameworks of DFS and adaptive capacity provides a lens to observe the power relations that mediate any benefits of agricultural diversification. Integrating analysis of the social and legal structures of the food system into the DFS for adaptive capacity formulation is a crucial step to transforming resilience thinking from an apolitical tool to transformative and power-aware applied science.

Testing roundabout capacity models: a practical aid for choosing the right one based on total capacity calculation

The determination of efficiency measures, under a known traffic demand, is a central aspect of roundabouts analysis. Many capacity formulations have been available for some time in different countries relating to different roundabout layouts. This paper refers to fifteen roundabout entry capacity models used above all in the European countries, highlighting their input requirements and their algorithm complexity. The formulations reviewed are then compared referring to a test roundabout, with a simple and widespread layout. Monte Carlo simulation have been performed considering 5,000 traffic distribution matrices for each capacity model. The results obtained are critically assessed resorting to the calculation of roundabout total capacity. The probability distributions of total capacity allow finding a model that stands out among all as an advisable choice for a suitable capacity formulation, acting as a synthesis of all those examined. This can be of considerable use in view of practical applications, for the design of efficient and safe roundabout intersections in situations in which a country-specific capacity formulation is not available.

On the Capacity of Amplitude Modulated Soliton Communication over Long Haul Fibers

The capacity limits of fiber-optic communication systems in the nonlinear regime are not yet well understood. In this paper, we study the capacity of amplitude modulated first-order soliton transmission, defined as the maximum of the so-called time-scaled mutual information. Such definition allows us to directly incorporate the dependence of soliton pulse width to its amplitude into capacity formulation. The commonly used memoryless channel model based on noncentral chi-squared distribution is initially considered. Applying a variance normalizing transform, this channel is approximated by a unit-variance additive white Gaussian noise (AWGN) model. Based on a numerical capacity analysis of the approximated AWGN channel, a general form of capacity-approaching input distributions is determined. These optimal distributions are discrete comprising a mass point at zero (off symbol) and a finite number of mass points almost uniformly distributed away from zero. Using this general form of input distributions, a novel closed-form approximation of the capacity is determined showing a good match to numerical results. Finally, mismatch capacity bounds are developed based on split-step simulations of the nonlinear Schro¨dinger equation considering both single soliton and soliton sequence transmissions. This relaxes the initial assumption of memoryless channel to show the impact of both inter-soliton interaction and Gordon–Haus effects. Our results show that the inter-soliton interaction effect becomes increasingly significant at higher soliton amplitudes and would be the dominant impairment compared to the timing jitter induced by the Gordon–Haus effect.