Motivation: EST data reflects variation in gene expression, but previous methods for finding coexpressed genes in EST data are subject to bias and vastly overstate the statistical significance of putatively coexpressed genes. Results: We introduce a new method (LNP) that reports reasonable $p$-values and also detects more biological relationships in human dbEST than do previous methods. In simulations with human dbEST library sizes, previous methods report $p$-values as low as $10^{-30}$ on 1/1,000 uncorrelated pairs, while LNP reports significance correctly. We validate the analysis on real human genes by comparing coexpressed pairs to GO annotations and find that LNP is more sensitive than three previous methods. We also find a small but statistically significant level of coexpression between interacting proteins relative to randomized controls. The LNP method is based on a log-normal prior on the distribution of expression levels. Availability: Source code in Java or R is available at http://ests.sourceforge.net/

Hypervideo is a form of interactive video that allows users to follow links to other video. A simple form of hypervideo, called "detail-on-demand video," provides at most one link from one segment of video to another, supporting a singlebutton interaction. Detail-on-demand video is well suited for interactive video summaries, because the user can request a more detailed summary while watching the video. Users interact with the video is through a special hypervideo player that displays keyframes with labels indicating when a link is available. While detail-on-demand summaries can be manually authored, it is a time-consuming task. To address this issue, we developed an algorithm to automatically generate multi-level hypervideo summaries. The highest level of the summary consists of the most important clip from each take or scene in the video. At each subsequent level, more clips from each take or scene are added in order of their importance. We give one example in which a hypervideo summary is created for a linear training video. We also show how the algorithm can be modified to produce a hypervideo summary for home video.

Community poster boards serve an important community building function. Posted fliers advertise services, events and people's interests, and invite community members to communicate, participate, interact and transact. In this paper we describe the design, development and deployment of the Plasma Poster Network, a network of large screen, digital community poster boards, the Plasma Posters. An initial deployment of Plasma Posters is within our own organization, a software research community made up of technologists and designers. We present our motivation and two fieldwork studies of online and offline information sharing before describing the Plasma Posters and the underlying information storage and distribution infrastructure. Finally, we summarize findings from qualitative and quantitative evaluations of Plasma Poster usage and conclude by elaborating on socio-technical challenges that have been faced in the design and deployment of the Plasma Poster Network.

Much effort has been expended in creating online information resources to foster social networks, create synergies between collocated and remote colleagues, and enhance social capital within organizations. Following the observation that physical bulletin boards serve an important community building and maintenance function, in this paper we describe a network of large screen, digital bulletin boards, the Plasma Poster Network. The function of this system is to bridge the gap between online community interactions and shared physical spaces. We describe our motivation, a fieldwork study of information sharing practices within our organization, and an internal deployment of Plasma Posters.

Much effort has been expended in creating online spaces for people to meet, network, share and organize. However, there is relatively little work, in comparison, that has addressed creating awareness of online community activities for those gathered together physically. We describe our efforts to advertise the online community spaces of CHIplace and CSCWplace using large screen, interactive bulletin boards that show online community information mixed with content generated at the conference itself. Our intention was to raise awareness of the online virtual community within the offline, face-to-face event. We describe the two deployments, at CHI 2002 and at CSCW 2002, and provide utilization data regarding people's participation within the physical and virtual locales.

To simplify the process of editing interactive video, we developed the concept of "detail-on-demand" video as a subset of general hypervideo where a single button press reveals additional information about the current video sequence. Detail-on-demand video keeps the authoring and viewing interfaces relatively simple while supporting a wide range of interactive video applications. Our editor, Hyper-Hitchcock, builds on prior work on automatic analysis to find the best quality video clips. It introduces video composites as an abstraction for grouping and manipulating sets of video clips. Navigational links can be created between any two video clips or composites. Such links offer a variety of return behaviors for when the linked video is completed that can be tailored to different materials. Initial impressions from a pilot study indicate that Hyper-Hitchcock is easy to learn although the behavior of links is not immediately intuitive for all users.

With digital still cameras, users can easily collect thousands of photos. Our goal is to make organizing and browsing photos simple and quick, while retaining scalability to large collections. To that end, we created a photo management application concentrating on areas that improve the overall experience without neglecting the mundane components of such an application. Our application automatically divides photos into meaningful events such as birthdays or trips. Several user interaction mechanisms enhance the user experience when organizing photos. Our application combines a light table for showing thumbnails of the entire photo collection with a tree view that supports navigating, sorting, and filtering photos by categories such as dates, events, people, and locations. A calendar view visualizes photos over time and allows for the quick assignment of dates to scanned photos. We fine-tuned our application by using it with large personal photo collections provided by several users.

In a meeting room environment with multiple public wall displays and personal notebook computers, it is possible to design a highly interactive experience for manipulating and annotating slides. For the public displays, we present the ModSlideShow system with a discrete modular model for linking the displays into groups, along with a gestural interface for manipulating the flow of slides within a display group. For the applications on personal devices, an augmented reality widget with panoramic video supports interaction among the various displays. This widget is integrated into our NoteLook 3.0 application for annotating, capturing and beaming slides on pen-based notebook computers.

Existing hypertext systems have emphasized either the navigational or spatial expression of relationships between objects. We are exploring the combination of these modes of expression in Hyper-Hitchcock, a hypervideo editor. Hyper-Hitchcock supports a form of hypervideo called "detail-on-demand video" due to its applicability to situations where viewers need to take a link to view more details on the content currently being presented. Authors of detail-on-demand video select, group, and spatially arrange video clips into linear sequences in a two-dimensional workspace. Hyper-Hitchcock uses a simple spatial parser to determine the temporal order of selected video clips. Authors add navigational links between the elements in those sequences. This combination of navigational and spatial hypertext modes of expression separates the clip sequence from the navigational structure of the hypervideo. Such a combination can be useful in cases where multiple forms of inter-object relationships must be expressed on the same content.

Many readers annotate passages that are important to their work. If we understand the relationship between the types of marks on a passage and the passage's ultimate utility in a task, then we can design e-book software to facilitate access to the most important annotated parts of the documents. To investigate this hypothesis and to guide software design, we have analyzed annotations collected during an earlier study of law students reading printed case law and writing Moot Court briefs. This study has allowed us to characterize the relationship between the students' annotations and the citations they use in their final written briefs. We think of annotations that relate directly to the written brief as high-value annotations; these annotations have particular, detectable characteristics. Based on this study we have designed a mark parser that analyzes freeform digital ink to identify such high-value annotations.

In this article we argue that discourse structure constrains the set of possible constituents in a discourse that can provide the relevant context for structuring information in a target sentence, while information structure critically constrains discourse structure ambiguity. For the speaker, the discourse structure provides a set of possible contexts for continuation while information structure assignment is independent of discourse structure. For the hearer, the information structure of a sentence together with discourse structure instructs dynamic semantics how rhematic information should be used to update the meaning representation of the discourse (Polanyi and van den Berg, 1996).

This paper describes the technical details of the Messtop (also know as 'AttrActive Windows') animated paper flier interface for the Plasma Posters.

A novel method is presented for inaudibly hiding information in an audio signal by subtly applying time-scale modification to segments of the signal. The sequence, duration, and degree of the time-scale modifications are the parameters which encode information in the altered signal. By comparing the altered signal with a reference copy, compressed and expanded regions can be identified and the hidden data recovered. This approach is novel and has several advantages over other methods: it is theoretically noiseless, it introduces no spectral distortion, and it is robust to all known methods of reproduction, compression, and transmission.

We created an improved layout algorithm for automatically generating visual video summaries reminiscent of comic book pages. The summaries are comprised of images from the video that are sized according to their importance. The algorithm performs a global optimization with respect to a layout cost function that encompasses features such as the number of resized images and the amount of whitespace in the presentation. The algorithm creates summaries that: always fit exactly into the requested area, are varied by containing few rows with images of the same size, and have little whitespace at the end of the last row. The layout algorithm is fast enough to allow the interactive resizing of the summaries and the subsequent generation of a new layout.

We created an alternative approach to existing video summaries that gives viewers control over the summaries by selecting hyperlinks to other video with additional information. We structure such summaries as "detail-on-demand" video, a subset of general hypervideo in which at most one link to another video sequence is available at any given time. Our editor for such video, Hyper-Hitchcock, provides a workspace in which an author can select and arrange video clips, generate composites from clips and from other composites, and place links between composites. To simplify dealing with a large number of clips, Hyper-Hitchcock generates iconic representations for composites that can be used to manipulate the composite as a whole. In addition to providing an authoring environment, Hyper-Hitchcock can automatically generate multi-level hypervideo summaries for immediate use or as the starting point for author modification.

This paper presents an information-driven audiovisual signal acquisition approach. This approach has several advantages: users are encouraged to assist in signal acquisition; available sensors are managed based on both signal characteristics and users' suggestions. The problem formulation is consistent with many well-known empirical approaches widely used in previous systems and may provide analytical explanations to these approaches. We demonstrate the use of this approach to pan/tilt/zoom (PTZ) camera management with field data.

A basic objective of ubiquitous computing research is ubiquitous information: the ability to utilize any content or service, using devices that are always at hand, over networks that don't tie us down. Although much progress has been made, the ideal remains elusive. This paper reflects on the interrelations among three dimensions of ubiquitous information: content, devices, and networks. We use our understanding of these dimensions to motivate our own attempt to create a ubiquitous information system by combining unlimited World Wide Web content with mobile phones and mobile phone networks. We briefly describe a middleware proxy system we developed to increase the usefulness of very small devices as Internet terminals. We conclude with a post-mortem analysis highlighting lessons learned for others interested in information systems for very small devices.

Everywhere we go, we are surrounded by shared devices: TVs, stereos, and appliances in the home; copiers, fax machines, and projectors in the office; phones and vending machines in public. Because these devices don't know who we are, they provide the same user interface and functionality to everyone. This paper describes a system for personalizing workplace document devices- projectors, public displays, and multi-function copiers-that has been in use for over two years in our organization. We compare user interfaces that are embedded (i.e., integrated or co-located with the shared device) versus portable (i.e., accessible via portable devices such as mobile phones or PDAs). We summarize lessons learned for others designing interfaces for shared ubiquitous devices.

Purveyors of knowledge management software have a disconcerting tendency to promote the myth that all problems may be solved by more powerful tools for the exchange of information in the workplace. This fallacy is based on the faulty assumption that knowledge management is about the management of knowledge (as if knowledge were a commodity that could be managed), as opposed to the management of people whose work depends critically on what they know. The origins of knowledge management are far more firmly rooted in the psychological legacy of organizational communication than they are in the technological legacy of information management systems. However, even organizational communication is an inadequate foundation, since various schools of thought in social theory, particularly the structuration theory of Anthony Giddens, inform us that interaction (in the workplace or in any other social setting) is not strictly limited to communication. Knowledge management thus requires moving beyond simplistic models of information exchange to more challenging problems of leveraging social interaction to the advantage of the enterprise. This paper focuses on the claim of structuration theory that the dimension of communication should be supplemented with additional dimensions of power and sanction. This perspective is then examined in light of a case study of crisis management practices, and the case study provides a basis for addressing implications for technological support.

This is a volume, edited by Ye and Churchill. The chapters detail the design of agent-baed technologies in service of collaborative and cooperative work practices.

In this paper we describe AttrActive Windows, a novel interface for presenting live, interactive, multimedia content on a network of public, digital, bulletin boards. Implementing a paper flyer metaphor, AttrActive Windows are paper-like in appearance and are attached to a virtual corkboard by virtual pushpins. Windows can therefore appear in different orientations, creating an attractive, informal look. Attractive Windows can also have autonomous behaviors that are consistent with the corkboard metaphor, like fluttering in the wind. We describe the AttrActive Windows prototype, and offer the results of an initial evaluative user study.

Shared freeform input is a technique for facilitating note taking across devices during a meeting. Laptop users enter text with a keyboard, whereas PDA and Tablet PC users input freeform ink with their stylus. Users can quickly reuse text and freeform ink already entered by others. We show how a new technique, freeform pasting, allowed us to deal with a variety of design issues such as quick and informal ink sharing, screen real estate, privacy and mixing ink-based and textual material.

This chapter is an introduction to an edited volume on Agnet supported cooperative work.

An introduction to a special issue on mediated communication.

We present a framework for analyzing the structure of digital media streams. Though our methods work for video,text,and audio,we concentrate on detecting the structure of digital music files. In the first step,spectral data is used to construct a similarity matrix calculated from inter-frame spectral similarity. The digital audio can be robustly segmented by correlating a ernel along the diagonal of the similarity matrix. Once segmented, spectral statistics of each segment are computed.In the second step,segments are clustered based on the self- similarity of their statistics. This reveals the structure of the digital music in a set of segment boundaries and labels.Finally,the music can be summarized by selecting clusters with repeated segments throughout the piece. The summaries can be customized for various applications based on the structure of the original music.