On exact solutions and numerics for cold, shallow, and thermocoupled ice sheets

This three section report can be regarded as an extended appendix to (Bueler, Brown, and Lingle 2006). First we give the detailed construction of an exact solution to a standard continuum model of a cold, shallow, and thermocoupled ice sheet. The construction is by calculation of compensatory accumulation and heat source functions which make a chosen pair of functions for thickness and temperature into exact solutions of the coupled system. The solution we construct here is ``TestG'' in (Bueler and others, 2006) and the steady state solution ``Test F'' is a special case. In the second section we give a reference C implementation of these exact solutions. In the last section we give an error analysis of a finite difference scheme for the temperature equation in the thermocoupled model. The error analysis gives three results, first the correct form of the Courant-Friedrichs-Lewy (CFL) condition for stability of the advection scheme, second an equation for error growth which contributes to understanding the famous ``spokes'' of (Payne and others, 2000), and third a convergence theorem under stringent fixed geometry and smoothness assumptions.Comment: 16 pages, two C codes; extended appendix to Bueler, Brown, and Lingle, "Exact solutions to the thermocoupled shallow ice approximation: effective tools for verification," submitted to J. Glacio

Cell Lineage Choice During Haematopoiesis: A Commemorative Issue in Honor of Professor Antonius Rolink

ca. 200 words; this text will present the book in all promotional forms (e.g. flyers). Please describe the book in straightforward and consumer-friendly terms. This special issue of the International Journal of Molecular Sciences contains a collection of articles by colleagues of Antonius (Ton) Gerardus Rolink (19/04/1953-06/08/2017) and honors Ton’s life and profound knowledge of and huge contribution to science. Ton participated in an FP7 Marie Curie Initial Training Network called DECIDE, and partners have submitted articles for this Special Issue. Scientists outside this network have also submitted articles. The articles examine various aspects of how the hematopoietic stem-cell gives rise to the different types of blood and immune cells. These include decision-making by the hematopoietic stem cell and the importance of controlling events within cells and the niches the cell resides in. New insights into these processes at the basic scientific level have given rise to an emerging new model for the development of blood cells. In turn, changes to our understanding of this process have led to new and exciting propositions regarding what goes wrong during the early stages of the development of leukemia

Carbon Pricing and the Transition from Voluntary to Mandatory Markets

The current national and global call for a coordinated and meaningful response to climate change concerns is certain to shift the United States from several regional and voluntary carbon markets today to a global compulsory market in the near future. In addition to the clear environmental benefits, this changing landscape will result in groups of carbon market "winners" and "losers" – some market segments will gain favor and market share while others will lose economic opportunity. The competitive disadvantage for traditional energy in a carbon-priced world will be a catalyst for market-driven innovations in renewable energy, and sustainable development. There are many opportunities where Austin and Texas stand to gain as larger carbon pricing components are realized. This primer looks to explore the political, economic, and design considerations that will affect the development of the carbon market.IC2 Institut

Computation of a combined spherical-elastic and viscous-half-space earth model for ice sheet simulation

This report starts by describing the continuum model used by Lingle & Clark (1985) to approximate the deformation of the earth under changing ice sheet and ocean loads. That source considers a single ice stream, but we apply their underlying model to continent-scale ice sheet simulation. Their model combines Farrell's (1972) elastic spherical earth with a viscous half-space overlain by an elastic plate lithosphere. The latter half-space model is derivable from calculations by Cathles (1975). For the elastic spherical earth we use Farrell's tabulated Green's function, as do Lingle & Clark. For the half-space model, however, we propose and implement a significantly faster numerical strategy, a spectral collocation method (Trefethen 2000) based directly on the Fast Fourier Transform. To verify this method we compare to an integral formula for a disc load. To compare earth models we build an accumulation history from a growing similarity solution from (Bueler, et al.~2005) and and simulate the coupled (ice flow)-(earth deformation) system. In the case of simple isostasy the exact solution to this system is known. We demonstrate that the magnitudes of numerical errors made in approximating the ice-earth system are significantly smaller than pairwise differences between several earth models, namely, simple isostasy, the current standard model used in ice sheet simulation (Greve 2001, Hagdorn 2003, Zweck & Huybrechts 2005), and the Lingle & Clark model. Therefore further efforts to validate different earth models used in ice sheet simulations are, not surprisingly, worthwhile.Comment: 36 pages, 16 figures, 3 Matlab program