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

The crystal structure of dipotassium tetranitroethide

Crystal structure of dipotassium tetranitroethide determined by single crystal X-ray diffraction technique

Critical loads for nutrient nitrogen for soil-vegetation systems

Members of the UK Critical Loads Advisory Group (CLAG) have calculated critical loads for nutrient nitrogen to produce maps for Great Britain. The results of three methods, based upon the conclusions from the Lokeberg workshop are described below. Two of these methods use the empirical approachand the other the steady state equation ("mass balance") for nitrogen saturation

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

Controlled access under review : improving the governance of genomic data access

In parallel with massive genomic data production, data sharing practices have rapidly expanded over the last decade. To ensure authorized access to data, access review by data access committees (DACs) has been utilized as one potential solution. Here we discuss core elements to be integrated into the fabric of access review by both established and emerging DACs in order to foster fair, efficient, and responsible access to datasets. We particularly highlight the fact that the access review process could be adversely influenced by the potential conflicts of interest of data producers, particularly when they are directly involved in DACs management. Therefore, in structuring DACs and access procedures, possible data withholding by data producers should receive thorough attention

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

A kinetics and mechanistic study of the atmospherically relevant reaction between molecular chlorine and dimethyl sulfide (DMS)

A gas-phase kinetics study of the atmospherically important reaction between Cl2 and dimethyl sulfide (DMS)Cl2 + CH3SCH3 → products has been made using a flow-tube interfaced to a photoelectron spectrometer. The rate constant for this reaction has been measured at 1.6 and 3.0 torr at T = (294 ± 2) K as (3.4 ± 0.7) × 10–14 cm3 molecule–1 s–1. Reaction (1) has been found to proceed via an intermediate, (CH3)2SCl2, to give CH3SCH2Cl and HCl as the products. The mechanism of this reaction and the structure of the intermediate were investigated using electronic structure calculations. A comparison of the mechanisms of the reactions between Cl atoms and DMS, and Cl2 and DMS has been made and the relevance of the results to atmospheric chemistry is discussed

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

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