Environments that are divided into regions lead to hierarchical encoding of space. Such memory structures are known to systematically distort estimates of distance and direction and affect spatial priming and memory recall. Here we present two navigation experiments in virtual environments that reveal an influence of environmental regions on human route planning and navigation behaviour. Follow...

Coarse woody debris (CWD) is recognized as an important component of British Columbia’s forest ecosystems linked to biodiversity and ecosystem processes. CWD represents high centers of biological interaction and energy exchange, symbolizing in many ways the complexity of forest ecosystems. Our research on lichens and bryophytes demonstrates that many species are either partially or entirely dep...

An abstract setting for robustly preconditioning symmetric positive definite (SPD) operators is presented. The term “robust” refers to the property of the condition numbers of the preconditioned systems being independent of mesh parameters and problem parameters. Important instances of such problem parameters are in particular (highly varying) coefficients. The method belongs to the class of ad...

INTRODUCTION Large dead wood or coarse woody debris (CWD) with a diameter >10 cm is an important resource for many arthropods and other animals that use it for food, oviposition sites, protection from environmental extremes, and foraging habitat (Elton 1966, Grove 2002b, Harmon and others 1986). Over 400 species of insects are known to use woody debris as a food resource in the Southeastern Uni...

The adaptive BDDC method is extended to the selection of face constraints in three dimensions. A new implementation of the BDDC method is presented based on a global formulation without an explicit coarse problem, with massive parallelism provided by a multifrontal solver. Constraints are implemented by a projection and sparsity of the projected operator is preserved by a generalized change of ...

Nanoindentation morphologies of crystalline copper have been probed at the grain scale. Experimental tests have been conducted on nanocrystalline (NC), ultrafine-grained (UFG), and coarse-grained (CG) copper samples with a new Berkvoich indenter at the strain rate of 0.04/s without holding time at an indentation depth of 2000 nm at room temperature. As the grain size increases, the height of th...

In this paper, we study robust two-level domain decomposition preconditioners for highly anisotropic multiscale problems. We give a construction of coarse spaces that employ initial multiscale basis functions and discuss techniques to achieve smaller dimensional coarse spaces without sacrificing the robustness of the preconditioner. We also present numerical results and discuss possible extensi...

We study the design of interactive video servers that store videos on disk arrays. In order to avoid the hot–spot problem in video servers it is conventional wisdom to stripe the videos over the disk array using Fine Grained Striping or Coarse Grained Striping techniques. Striping, however, increases the seek and rotational overhead, thereby reducing the throughput of the disk array. Our result...

A scalable FETI–DP (Dual-Primal Finite Element Tearing and Interconnecting) algorithm for the Stokes problem is developed and analyzed. Advantages of this approach are a coarse problem without primal pressure unknowns and the use of a relatively cheap lumped preconditioner. Especially in three dimensions, these advantages provide a more robust and faster FETI-DP algorithm. In three dimensions, ...

We employ systematic coarse graining techniques to derive hydrodynamic equations from Grad’s ten-moment equations. The coarse graining procedure is designed such that it manifestly preserves the thermodynamic structure of the equations. The relevant thermodynamic structure and the coarse graining recipes suggested by statistical mechanics are described in detail and are illustrated by the examp...