In Nature this week

April 27, 2007

  1. Of course the big story, as I blogged elsewhere, is the higher dimensional generalizations of the Neumann-Mullins rule of grain growth by MacPherson and Srolovitz:

    Cellular structures or tessellations are ubiquitous in nature. Metals and ceramics commonly consist of space-filling arrays of single-crystal grains separated by a network of grain boundaries, and foams (froths) are networks of gas-filled bubbles separated by liquid walls. Cellular structures also occur in biological tissue, and in magnetic, ferroelectric and complex fluid contexts. In many situations, the cell/grain/bubble walls move under the influence of their surface tension (capillarity), with a velocity proportional to their mean curvature. As a result, the cells evolve and the structure coarsens. Over 50 years ago, von Neumann derived an exact formula for the growth rate of a cell in a two-dimensional cellular structure (using the relation between wall velocity and mean curvature, the fact that three domain walls meet at 120° and basic topology). This forms the basis of modern grain growth theory. Here we present an exact and much-sought extension of this result into three (and higher) dimensions. The present results may lead to the development of predictive models for capillarity-driven microstructure evolution in a wide range of industrial and commercial processing scenarios—such as the heat treatment of metals, or even controlling the ‘head’ on a pint of beer.

  2. Henry Gee reviews The Discovery of the Hobbit: The scientific breakthrough that changed the faceof human history; and, John Hawks is not happy about the review (though he seems to have liked the book)–his review of the review is a must read, at least for sections like these:

    …Gee spends several paragraphs expositing on his own role in the publication of the Homo floresiensis announcement. We learn some interesting little facts, like how the authors wanted to name the species “Sundanthropus floresianus” until a reviewer pointed out that future students would confuse the name with a flowery butt.I kid you not. Nature has a layer of reviewers to take tushie references out of taxonomy. Somehow they can’t tell a left femur from a right, but they’re on the watch for sphincter-species!

  3. How does one weigh molecules, single cell virus, and bacteria whose weight are of the order of a few hundreds of femtograms (and, which are in a solution)? Liesbeth Venema describes a method that has been developed recently and reported in the same issue of Nature.
  4. Martin Campbell-Kelly pays his tributes to John Backus, the inventor of FORTRAN in an obituary piece.