Hollow vortices and minimal surfaces

We consider an overdetermined elliptic problem known as the hollow vortex problem. We prove that the solutions to this problem are in 1:1 correspondence with minimal graphs bounded by horizontal symmetry lines. We use this correspondence to give various examples of domains with hollow vortices.Comment: 22 pages, 7 figure

Chaco Canyon: A Contested Memory Anchor in the North American Southwest

Natural and archaeological places are powerful loci for social memories and continually negotiated meanings. As ‘memory anchors’ they are focal points for the construction of memory and meaning, and can become flashpoints for disputes over access, land-use, and knowledge claims among stakeholders with contradictory interests. In the North American Southwest the competing claims of Native American tribes, archaeologists, government bureaucrats, tourists, and the mining industry come into sharp relief. In this paper, I explore how the UNESCO World Heritage Site of Chaco Canyon figures prominently in the origin stories and sacred geographies of contemporary Pueblo and Navajo peoples – two indigenous groups with competing political stakes in the present

Dynamics and efficiency of a self-propelled, diffusiophoretic swimmer

Active diffusiophoresis - swimming through interaction with a self-generated, neutral, solute gradient - is a paradigm for autonomous motion at the micrometer scale. We study this propulsion mechanism within a linear response theory. Firstly, we consider several aspects relating to the dynamics of the swimming particle. We extend established analytical formulae to describe small swimmers, which interact with their environment on a finite lengthscale. Solute convection is also taken into account. Modeling of the chemical reaction reveals a coupling between the angular distribution of reactivity on the swimmer and the concentration field. This effect, which we term "reaction induced concentration distortion", strongly influences the particle speed. Building on these insights, we employ irreversible, linear thermodynamics to formulate an energy balance. This approach highlights the importance of solute convection for a consistent treatment of the energetics. The efficiency of swimming is calculated numerically and approximated analytically. Finally, we define an efficiency of transport for swimmers which are moving in random directions. It is shown that this efficiency scales as the inverse of the macroscopic distance over which transport is to occur.Comment: 16 pages, 11 figure

Alien Registration- Van Dyke, Frank M. (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/21671/thumbnail.jp

Quadra v. Superior Court of the City and County of San Francisco: A Challenge to the Composition of the San Francisco Grand Jury

Quadra v. Superior Court involves a challenge to the procedures used in the selection of San Francisco\u27s investigative grand jury. The Hastings Law Journal has reprinted plaintiffs\u27 memoranda, which argue that such procedures should be governed by the standards applicable to indicting grand juries