Trade-offs between gaze and working memory use.

Eye movements during natural tasks suggest that observers do not use working memory to capacity but instead use eye movements to acquire relevant information immediately before needed. Results here however, show that this strategy is sensitive to memory load and to observers' expectations about what information will be relevant. Depending upon the predictability of what object features would be needed in a brick sorting task, subjects spontaneously modulated the order in which they sampled and stored visual information using working memory more when the task was predictable and reverting to a just-in-time strategy when the task was unpredictable and the memory load was higher. This self organization was evidenced by subjects' sequence of eye movements and also their sorting decisions following missed feature changes. These results reveal that attentional selection, fixations, and use of working memory reflect a dynamic optimization with respect to a set of constraints, such as task predictablity and memory load. They also reveal that change blindness depends critically on the local task context, by virtue of its influence on the information selected for storage in working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task Demands Control Acquisition and Storage of Visual Information.

Attention and working memory limitations set strict limits on visual representations, yet researchers have little appreciation of how these limits constrain the acquisition of information in ongoing visually guided behavior. Subjects performed a brick sorting task in a virtual environment. A change was made to 1 of the features of the brick being held on about 10% of trials. Rates of change detection for feature changes were generally low and depended on the pick-up and put-down relevance of the feature to the sorting task. Subjects' sorting decision suggests that changes may be missed because of a failure to update the changed feature. The authors also explore how hand and eye behavior are coordinated for strategic acquisition and storage of visual information throughout the task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The European Space Agency's Deep-Space Antennas

The European Space Agency (ESA) is today autonomously flying three interplanetary missions: Rosetta traveling to the comet Churyumov-Gerasimenko and the two orbiters Mars Express and Venus Express. The capability of supporting these and future deep-space missions is the consequence of a farsighted decision taken in 1996 to expand the ESA network of 15-m tracking antennas into the deep-space domain. The ambitious plan to provide around-the-clock coverage to all ESA interplanetary missions is almost completed: two deep-space antennas, located in New Norcia (Australia) and Cebreros (Spain), have been in operation since 2002 and 2005, respectively, while a third antenna is planned for 2011. This paper presents the two existing antennas starting from the underlying system requirements originated from the Rosetta mission, which was the most demanding in terms of required performance. The selected architecture is then described, followed by a detailed discussion about the critical performances that play a major role in deep-space support and the associated design issues.     

A Pseudospectral Multi-Domain Method for the Incompressible Navier–Stokes Equations

A pseudospectral method for the solution of incompressible flow problems based on an iterative solver involving an implicit treatment of linearized convective terms is presented. The method is designed for moderately complex geometries by means of a multi-domain approach. Key components are a Chebyshev collocation discretization, a special pressure-correction scheme and a restarted GMRES method with a preconditioner derived from a fast direct solver. The performance of the method with respect to the multi-domain functionality is investigated and compared to finite-volume approaches.