EDGES AND RUSHES OF MINNESOTA: THE COMPLETEGUIDETOSPECIESIDENTIFICATION. Welby R. Smith; photography by Richard Haug.

Even the most seasoned individual with a plant identification background can relate to the difficulty of identifying sedges and rushes to the species level. Historically, one has had to rely on dichotomous keys to identify a sedge or rush species in the field. After hours of frustration, a person ends up collecting the plant and, if lucky, bringing the collection back to a herbarium where it can be compared to known specimens. I have been collecting and identifying sedge and rush species for over 25 years, and author Welby Smith along with photographer Richard Haug have published what I believe will be considered one of the most usable field guides for sedge and rush identification in the upper Midwest. I believe I should mention early in this review what makes this book such an amazing resource for field identification of sedges and rushes—the photography. The photography is of the highest quality I have ever seen! The array of photographs included with each species focuses on the characteristics that clearly differentiate one species from another. Each species usually has a photograph of the whole plant and sometimes the plant within its habitat. There are always photographs of the inflorescence and fruit, including perigynia or capsules and achenes or seeds. For example, the genus Carex includes photographs of the scale (sometimes the scale with the perigynium), the perigynium (usually dorsal and ventral views), and the achene, and in certain cases there are multiple photographs of each showing the changes in color during the season. Most of the photographs are of living plants and their parts, which is exactly what one would see in the field. Having pointed out this fact, it is mind-boggling how much time and effort that the people involved in the production of this book must have dedicated to putting this resource together. It had to be a passion or, at least, an obsession toward perfection

User study on 3D multitouch interaction (3DMi) and gaze on surface computing

On a multitouch table, user’s interactions with 3D virtual representations of real objects should be influenced by task and their perceived physical characteristics. This article explores the development and user study of an interactive 3D application that allows users to explore virtual heritage objects on a surface device. To-date, most multitouch has focused on 2D or 2.5D systems. A user-study is reported where we analyse their multimodal behaviour – specifically how they interact on a surface device with objects that have similar properties to physical versions and the users’ associated gaze patterns with touch. The study reveals that gaze characteristics are different according to their interaction intention in terms of position and duration of visual attention. We discovered that virtual objects afford the perception of haptic attributes ascribed to their equivalent physical objects, and that differences in the summary statistics of gaze showed consistent characteristics between people and differences between natural and task based activities. An awareness of user behaviours using natural gestures can inform the design of interactive 3D applications which complements the user’s model of past experience with physical objects and with GUI interaction

Fractal Scales in a Schwarzschild Atmosphere

Recently, Glass and Krisch have extended the Vaidya radiating metric to include both a radiation fluid and a string fluid [1999 Class. Quantum Grav. vol 16, 1175]. Mass diffusion in the extended Schwarzschild atmosphere was studied. The continuous solutions of classical diffusive transport are believed to describe the envelope of underlying fractal behavior. In this work we examine the classical picture at scales on which fractal behavior might be evident.Comment: to appear in Class. Quantum Gra

Dimension in a Radiative Stellar Atmosphere

Dimensional scales are examined in an extended 3+1 Vaidya atmosphere surrounding a Schwarzschild source. At one scale, the Vaidya null fluid vanishes and the spacetime contains only a single spherical 2-surface. Both of these behaviors can be addressed by including higher dimensions in the spacetime metric.Comment: to appear in Gen. Rel. Gra

Finite time and asymptotic behaviour of the maximal excursion of a random walk

We evaluate the limit distribution of the maximal excursion of a random walk in any dimension for homogeneous environments and for self-similar supports under the assumption of spherical symmetry. This distribution is obtained in closed form and is an approximation of the exact distribution comparable to that obtained by real space renormalization methods. Then we focus on the early time behaviour of this quantity. The instantaneous diffusion exponent $\nu_n$ exhibits a systematic overshooting of the long time exponent. Exact results are obtained in one dimension up to third order in $n^{-1/2}$. In two dimensions, on a regular lattice and on the Sierpi\'nski gasket we find numerically that the analytic scaling $\nu_n \simeq \nu+A n^{-\nu}$ holds.Comment: 9 pages, 4 figures, accepted J. Phys.