March 6, 2006

Piles of PDA files

Despite the small screens of handheld devices we continue to try to do more and more with the likes of cellphones and PDAs, from watching television shows to running desktop applications. Researchers have been trying to overcome the small screen limitation in recent years by using imaginary space around the screens.

A pen-based technique developed by Stanford University researchers lets users flick files into virtual piles beyond the periphery of the screen. The piles, which are independent of the underlying operating system file structure, organize files and keep large numbers of files near at hand. Dragging a semicircle at the edge of the screen to the center pulls the corresponding pile onto the screen. The system allows users to maintain multiple workspaces, each containing a set of piles.

Multiple users can share piles if their handheld devices have wireless data links. One potential application is for teams of workers collecting data in the field.

In the researchers' experiments users were able to manage as many as ten piles at a time, and remembered the locations of their piles several days after creating them.

(Piles Across Space: Breaking the Real-Estate Barrier on PDAs, Computer-Human Interaction (CHI) 2006, April 22-28, Montréal, Canada)

Motion models how we meet

What does math have to do with friendship and sex? Quite a bit, these days. Mathematical models are emerging as a useful tool for studying and monitoring social networks.

Networks have three principal characteristics: a structure that indicates the average degrees of separation between nodes, a clustering coefficient that indicates the sizes and distribution of subgroups, and a dynamical evolution that indicates the rate at which links and clusters are formed and broken.

Scientists from the University of Stuttgart in Germany, Federal University of Ceará in Brazil, and the Center for Theoretical and Computational Physics in Portugal have developed a model that captures all three characteristics using a single behavior -- motion. The model contains mobile agents that move randomly and collide with each other, with collisions representing acquaintanceships.

The researchers' model accurately represented the characteristics of several networks: friendships among some 90,000 students at 84 schools in the U.S, and sexual contacts among a network of 250 people.

The model could be used to map many types of networks, including those that inform disease tracking and treatment, sociological studies, and law enforcement.

(System of Mobile Agents to Model Social Networks, Physical Review Letters, March 3, 2006)

Bits and pieces

Fingers do the browsing

A cell phone browsing technique arranges information hierarchically in three-by-three grids that correspond to the keypad, allowing users to navigate through each layer with a single keystroke.

(FaThumb: A Facet-based Interface for Mobile Search, Computer-Human Interaction (CHI) 2006, April 22-28, Montréal, Canada)

Commands hover, data touches

A pen-based interface for handheld devices tracks command gestures made above the screen. The software differentiates between in-air command gestures and information written with the pen touching the screen.

(Hover Widgets: Using the Tracking State to Extend the Capabilities of Pen-Operated Devices, Computer-Human Interaction (CHI) 2006, April 22-28, Montréal, Canada)

Cropping by eye

A gaze-tracking system automates photo cropping by determining the important parts of an image based on how the user looks at it. The technique could be used for automatic snapshot editing, adaptive image displays and generating thumbnails.

(Gaze-Based Interaction for Semi-Automatic Photo Cropping, Computer-Human Interaction (CHI) 2006, April 22-28, Montréal, Canada)

Electric field refrigeration

An electric field cools films of lead zirconium titanium oxide -- a phenomenon dubbed giant electrocaloric effect. Like thermovoltaic materials, electrocaloric materials could be used to cool computer chips and make motorless, gasless refrigerators.

(Giant Electrocaloric Effect in Thin-Film PbZr_0.95Ti_0.05O₃, Science, March 3, 2006)