Groundwater, health and livelihoods in Africa

Groundwater is Africa’s most precious natural resource, providing reliable water supplies to at least a third of the continent’s population. Where it can be found, groundwater has many advantages over river water: it is naturally protected from contamination, able to provide water throughout dry seasons and droughts, and can often be found close to the point of need and therefore developed incrementally and at low cost

Sobczyk's simplicial calculus does not have a proper foundation

The pseudoscalars in Garret Sobczyk's paper \emph{Simplicial Calculus with Geometric Algebra} are not well defined. Therefore his calculus does not have a proper foundation

Groundwater resilience to climate change in Africa

In Africa, groundwater is the major source of drinking water and its use for irrigation is forecast to increase substantially to combat growing food insecurity. Climate change along with rapid population growth are likely to impact all water resources, but the response of groundwater will be slower than that of surface water providing a potential buffer to help support adaptation. Here an interdisciplinary team from the UK and Africa present the results of a DFID funded research project to provide the first quantitative assessment of continental groundwater resources for Africa and to examine how resilient they are to climate change

Entanglement, joint measurement, and state reduction

Entanglement is perhaps the most important new feature of the quantum world. It is expressed in quantum theory by the joint measurement formula. We prove the formula for self-adjoint observables from a plausible assumption, which for spacelike separated measurements is an expression of relativistic causality. State reduction is simply a way to express the JMF after one measurement has been made, and its result known.Comment: New material. Reformatted for journal submissio

The Price Equation

I give concise derivations of Price's equation and the criteria for kin and group selection, prove that kin and group selection are equivalent, and discuss the controversies about altruism

Faraday Conversion in Turbulent Blazar Jets

Low ($\lesssim 1\%$) levels of circular polarization (CP) detected at radio frequencies in the relativistic jets of some blazars can provide insight into the underlying nature of the jet plasma. CP can be produced through linear birefringence, in which initially linearly polarized emission produced in one region of the jet is altered by Faraday rotation as it propagates through other regions of the jet with varying magnetic field orientation. Marscher has begun a study of jets with such magnetic geometries using the Turbulent Extreme Multi-Zone (TEMZ) model, in which turbulent plasma crossing a standing shock in the jet is represented by a collection of thousands of individual plasma cells, each with distinct magnetic field orientations. Here we develop a radiative transfer scheme that allows the numerical TEMZ code to produce simulated images of the time-dependent linearly and circularly polarized intensity at different radio frequencies. In this initial study, we produce synthetic polarized emission maps that highlight the linear and circular polarization expected within the model.Comment: 17 pages, 13 figures, accepted for publication in Ap