ravenclaw @ravenclaw@qoto.org

Given the rapid recent trend of urbanization, a better understanding of how urban infrastructure mediates socioeconomic interactions and economic systems is of vital importance. While the accessibility of location-enabled devices as well as large-scale datasets of human activities, has fueled significant advances in our understanding, there is little agreement on the linkage between socioeconomic status and its influence on movement patterns, in particular, the role of inequality. Here, we analyze a heavily aggregated and anonymized summary of global mobility and investigate the relationships between socioeconomic status and mobility across a hundred cities in the US and Brazil. We uncover two types of relationships, finding either a clear connection or little-to-no interdependencies. The former tend to be characterized by low levels of public transportation usage, inequitable access to basic amenities and services, and segregated clusters of communities in terms of income, with the latter class showing the opposite trends. Our findings provide useful lessons in designing urban habitats that serve the larger interests of all inhabitants irrespective of their economic status.

We consider a demand management problem of an energy community, in which several users obtain energy from an external organization such as an energy company, and pay for the energy according to pre-specified prices that consist of a time-dependent price per unit of energy, as well as a separate price for peak demand. Since users' utilities are private information which they may not be willing to share, a mediator, known as the planner, is introduced to help optimize the overall satisfaction of the community (total utility minus total payments) by mechanism design. A mechanism consists of message spaces, and a set of tax and allocation functions for each user. Once we implement the mechanism, each user reports a message chosen from her own message space, and then receives some amount of energy determined by the allocation function and pays the tax specified by the tax function. A desirable mechanism induces a game in which Nash equilibria (NE) provides an allocation that coincides with the optimal allocation for the community. As a starting point, we design a standard, "centralized" mechanism for the energy community with desirable properties such as full implementation, strong budget balance and individual rationality for both users and the planner. Then we extend this mechanism to the case of communities where message exchanges only happen among neighborhoods, and consequently, the tax and allocation functions of each user are only determined by the messages from her neighbors. All the properties designed for the centralized mechanism are preserved in the distributed mechanism. Subsequently, we address the problem of learning guarantees for both mechanisms. One set of learning dynamic was found in this primary work, that guarantees users will reach NE if they follow these dynamics.

After some more than four centuries from the formulation and publication (in Astronomia Nova) of the Kepler's Equation, which relates the eccentric (and, intermediately, the true) anomaly of the planetary trajectories to the uniformly flowing time, in accordance with his Second ("Area") law, the subsequently -- in course of development of Orbital Mechanics -- to the 2${}^{nd}$ law related and formally derived non-existent (zero-valued) transverse acceleration is refuted. Certain implications to Elliptic Integration, Symplectic Integration, Symplectic Geometry/Topology, as well as the connection between physical and mathematical continua in the context of the multi-level, scale-invariant mechanics/dynamics (with the augmented central and torquing forces) are also briefly hinted to.

When students are learning to use math in physics, one of the most important ideas they need to learn is that equations are not just calculational tools; they represent relationships between physical variables that change together (covary). How much a change in one variable or parameter is associated with a change in another depends on how they appear in the equation: their functional dependence. Understanding this sort of relationship is rarely taught in introductory mathematics classes, and students who have not yet learned to blend conceptual ideas with mathematical symbols may not see the relevance and power of this idea. We need to explicitly teach functional dependence as part of our effort to help students to learn to use math productively in science.

We are pleased to announce that the KDE Community Edition (CE) PinePhone is now available for pre-order. This edition of the PinePhone ships with a tailored build of Plasma Mobile built upon Manjaro…

Flappy bird in 228 bytes (improved!). GitHub Gist: instantly share code, notes, and snippets.