A multimedia interactive conferencing application for personalworkstations

The multimedia interactive conferencing application (MICA), a personal-workstation application for multipoint visual teleconferencing, is described. MICA allows people at two or more locations to share visual material such as documents, photographs, and computer screens in a highly interactive way. It supports the distribution, storage, retrieval, and high-quality display of visuals, real-time interaction by pointing and annotation, and meeting services facilities. The context of multimedia teleconferencing and computer-supported cooperative work is established, relating earlier research to the design of MICA. The services MICA offers are outlined. The handling, compression, and display of multiple media, and the design of a suitable user interface for MICA are discussed     

A cold fusion chronology

To assess the historical and sociological significance of the cold fusion saga, researchers need accurate information about the dates of various events associated with the saga. Based on materials in the Cornell Cold Fusion Archive, this article provides both a chronology and citations to documentary evidence for cold fusion events from 1926 to the end of 1990.     

Fluorescence in dual-wavelength pumpedHo3+-fluorozirconate fibers

The authors study holmium-doped fluorozirconate fiber pumped simultaneously by HeNe and a laser-doped diode contrapropagating through the fiber. The experiments are described. Dual-wavelength induced fluorescence bands were identified. The two pumping wavelengths were 630 and 830 nm, and strong enhancement of the fluorescence is observed in the 545- and 750-nm ranges. The fiber fluorescence efficiency is modeled with the use of perturbation theory describing the propagation of all the waves involved in the absorption-emission process. Experimental results and theory are qualitatively in agreement     

Design of signal-adapted multidimensional lifting scheme for lossy coding

This paper proposes a new method for the design of lifting filters to compute a multidimensional nonseparable wavelet transform. Our approach is stated in the general case, and is illustrated for the 2-D separable and for the quincunx images. Results are shown for the JPEG2000 database and for satellite images acquired on a quincunx sampling grid. The design of efficient quincunx filters is a difficult challenge which has already been addressed for specific cases. Our approach enables the design of less expensive filters adapted to the signal statistics to enhance the compression efficiency in a more general case. It is based on a two-step lifting scheme and joins the lifting theory with Wiener's optimization. The prediction step is designed in order to minimize the variance of the signal, and the update step is designed in order to minimize a reconstruction error. Application for lossy compression shows the performances of the method.     

Time of Relaxation to a Stationary Nonequilibrium Distribution of Brownian Particles in a System with a Source and a Sink

We generalize a method for determination of time scales of nonstationary diffusion in a one-dimensional medium. The time of relaxation to a stationary non-equilibrium density of substance in a system with a source, a sink, and an arbitrary potential profile are obtained and studied in detail. A few specific examples are considered.     

High-power 980 nm quantum dot broad area lasers

High-power quantum dot broad area lasers emitting at 980 nm are presented. Continuous-wave output powers of 4.3 W from a 50 /spl mu/m stripe width laser and of 6.3 W from a 100 /spl mu/m stripe width laser were achieved at 15/spl deg/C     

Very high-order microring resonator filters for WDM applications

High-order microring resonators having from 1 to 11 coupled cavities are demonstrated. These filters exhibit low loss, flat tops, and out-of-band rejection ratios that can exceed 80 dB. They achieve performance that is suitable for commercial applications.     

Surgical navigation by autostereoscopic image overlay of integral videography

This paper describes an autostereoscopic image overlay technique that is integrated into a surgical navigation system to superimpose a real three-dimensional (3-D) image onto the patient via a half-silvered mirror. The images are created by employing a modified version of integral videography (IV), which is an animated extension of integral photography. IV records and reproduces 3-D images using a microconvex lens array and flat display; it can display geometrically accurate 3-D autostereoscopic images and reproduce motion parallax without the need for special devices. The use of semitransparent display devices makes it appear that the 3-D image is inside the patient's body. This is the first report of applying an autostereoscopic display with an image overlay system in surgical navigation. Experiments demonstrated that the fast IV rendering technique and patient-image registration method produce an average registration accuracy of 1.13 mm. Experiments using a target in phantom agar showed that the system can guide a needle toward a target with an average error of 2.6 mm. Improvement in the quality of the IV display will make this system practical and its use will increase surgical accuracy and reduce invasiveness.     

Protocol design for scalable and reliable group rekeying

We present the design and specification of a protocol for scalable and reliable group rekeying together with performance evaluation results. The protocol is based upon the use of key trees for secure groups and periodic batch rekeying. At the beginning of each rekey interval, the key server sends a rekey message to all users consisting of encrypted new keys (encryptions, in short) carried in a sequence of packets. We present a scheme for identifying keys, encryptions, and users, and a key assignment algorithm that ensures that the encryptions needed by a user are in the same packet. Our protocol provides reliable delivery of new keys to all users eventually. It also attempts to deliver new keys to all users with a high probability by the end of the rekey interval. For each rekey message, the protocol runs in two steps: a multicast step followed by a unicast step. Proactive forward error correction (FEC) multicast is used to reduce delivery latency. Our experiments show that a small FEC block size can be used to reduce encoding time at the server without increasing server bandwidth overhead. Early transition to unicast, after at most two multicast rounds, further reduces the worst-case delivery latency as well as user bandwidth requirement. The key server adaptively adjusts the proactivity factor based upon past feedback information; our experiments show that the number of NACKs after a multicast round can be effectively controlled around a target number. Throughout the protocol design, we strive to minimize processing and bandwidth requirements for both the key server and users.     

One-, two-, and three-photon pumped lasing in a novel liquid dye salt system

We report the observation of one-, two-, and three-photon pumped lasing in the same medium, a novel liquid dye salt system when excited by pulsed 0.532-, 1.06-, and /spl sim/1.49-/spl mu/m coherent radiation pulses, respectively. Since the gain medium is a liquid and not a solution, it contains a significantly higher effective dye concentration and, therefore, is highly suitable for multiphoton pumped lasing and optical power limiting applications. The lasing spectra, temporal waveforms, near- and far-field intensity distributions, and output/input efficiency were measured under the conditions of one-, two-, and three-photon pump configurations.