6332225
Observing a volume rendered fetus within a pregnant patient
Augmented reality systems with see-through headmounted displays have been used primarily for applications that are possible with today's computational capabilities. We explore possibilities for a particular application-in-place, real-time 3D ultrasound visualization-without concern for such limitations. The question is not "How well could we currently visualize the fetus in real time," but "How well could we see the fetus if we had sufficient compute power?" Our video sequence shows a 3D fetus within a pregnant woman's abdomen-the way this would look to a HMD user. Technical problems in making the sequence are discussed. This experience exposed limitations of current augmented reality systems; it may help define the capabilities of future systems needed for applications as demanding as real-time medical visualization.<<ETX>>
30643736
Compound Brushing Explained†
This paper proposes a conceptual model called compound brushing for modeling the brushing techniques used in dynamic data visualization. In this approach, brushing techniques are modeled as higraphs with five types of basic entities: data, selection, device, renderer, and transformation. Using this model, a flexible visual programming tool is designed not only to configure and control various common types of brushing techniques currently used in dynamic data visualization but also to investigate new brushing techniques.
7036833
Dynamic Service Discovery for Mobile Computing: Intelligent Agents Meet Jini in the Aether
The emergence of ad-hoc pervasive connectivity for devices based on Bluetooth-like systems provides a new way to create applications for mobile systems. We seek to realize ubiquitous computing systems based on the cooperation of autonomous, dynamic and adaptive components (hardware as well as software) which are located in vicinity of one another. In this paper we present this vision. We also describe a prototype system we have developed that implements parts of this vision – in particular a system that combines agent oriented and service oriented approaches and provides dynamic service discovery. We point out why existing systems such as Jini are not suited for this task, and how our system improves on them.
7740275
FIREMAN: a toolkit for firewall modeling and analysis
Security concerns are becoming increasingly critical in networked systems. Firewalls provide important defense for network security. However, misconfigurations in firewalls are very common and significantly weaken the desired security. This paper introduces FIREMAN, a static analysis toolkit for firewall modeling and analysis. By treating firewall configurations as specialized programs, FIREMAN applies static analysis techniques to check misconfigurations, such as policy violations, inconsistencies, and inefficiencies, in individual firewalls as well as among distributed firewalls. FIREMAN performs symbolic model checking of the firewall configurations for all possible IP packets and along all possible data paths. It is both sound and complete because of the finite state nature of firewall configurations. FIREMAN is implemented by modeling firewall rules using binary decision diagrams (BDDs), which have been used successfully in hardware verification and model checking. We have experimented with FIREMAN and used it to uncover several real misconfigurations in enterprise networks, some of which have been subsequently confirmed and corrected by the administrators of these networks
14045822
Optimizing search by showing results in context
We developed and evaluated seven interfaces for integrating semantic category information with Web search results. List interfaces were based on the familiar ranked-listing of search results, sometimes augmented with a category name for each result. Category interfaces also showed page titles and/or category names, but re-organized the search results so that items in the same category were grouped together visually. Our user studies show that all Category interfaces were more effective than List interfaces even when lists were augmented with category names for each result. The best category performance was obtained when both category names and individual page titles were presented. Either alone is better than a list presentation, but both together provide the most effective means for allowing users to quickly examining search results. These results provide a better understanding of the perceptual and cognitive factors underlying the advantage of category groupings and provide some practical guidance to Web search interface designers.
1165445
Physical planning of on-chip interconnect architectures
Interconnect architecture plays an important role in determining the throughput of meshed communication structures. We assume a mesh structure with uniform communication demand for communication. A multi-commodity flow (MCF) model is proposed to find the throughput for several different routing architectures. The experimental results reveal several trends: 1. The throughput is limited by the capacity of the middle row and column in the mesh, simply enlarging the congested channel cannot produce better throughput. A flexible chip shape provides around 30% throughput improvement over a square chip of equal area. 2. A 45-degree mesh allows 17% throughput improvement over 90-degree mesh and a 90-degree and 45-degree mixed mesh provides 30% throughput improvement. 3. To achieve maximum throughput on a mixed Manhattan and diagonal interconnect architecture, the best ratio of the capacity for diagonal routing layers and the capacity for Manhattan routing layers is 5.6. 4. Incorporating a simplified via model, interleaving diagonal routing layers and Manhattan routing layer is the best way to organize the wiring directions on different layers.
9752024
Invadable self-assembly: combining robustness with efficiency
DNA self-assembly is emerging as a key paradigm for nano-technology, nano-computation, and several related disciplines. In nature, DNA self-assembly is often equipped with explicit mechanisms for both error prevention and error correction. For artificial self-assembly, these problems are even more important since we are interested in assembling large systems with great precision. So far, theoretical studies of DNA self-assembly have primarily focused on the efficiency of the assembly process in terms of the program size and the running time. In this paper, we perform a preliminary study of algorithms for DNA self-assembly that are both robust and efficient.Strand invasion is an important error-correction mechanism observed in several natural self-assembling systems. We first define invadable self-assemblies as self-assembling systems which can effectively use the strand invasion mechanism for error-correction. We then show that O(log2 n/ log log n) tiles are sufficient to assemble an n × n square in this model. The running time of our system is Õ (n). We obtain our result by growing a counter which simulates Chinese remaindering. The running time and the program size of our invadable system are within polylogarithmic factors of known lower bounds for general systems, i.e. the efficiency penalty for obtaining robustness is small in our model. We also show how to simulate an arbitrary Turing machine using an invadable self-assembly system.