This paper describes a microfluidic system in which fluids are pumped by centrifugal force through microscopic channels defined in a plastic disk in order to perform complex analytical processes. The channels are created either by casting poly(dimethylsiloxane) against molds fabricated by photolithography or by conventional machining of poly(methyl methyacrylate). The channels have a wide range of diameters (5 μm−0.5 mm) and depths (16 μm−3 mm). Fluids are loaded into reservoirs near the center of the disk, the disk is rotated on the shaft of a simple motor at 60−3000 rpm, and the fluids are pumped outward by centrifugal force through microfluidic networks. The control of flow in the time domain, i.e., gating, is achieved by the use of passive valves based on capillary forces. Flow rates ranging from 5 nL/s to >0.1 mL/s have been achieved using channels of different dimensions and different rates of rotation. The method of pumping is insensitive to many physicochemical properties of the liquid, such as pH and ionic strength, so it has been possible to pump biological fluids, such as blood and urine, a buffer containing a detergent, and some organic solvents. A system that performs multiple (48) enzymatic assays simultaneously using colorimetric detection on a dedicated instrument has been demonstrated. These integrated assays have been used both to yield the Michaelis constant (K m) of an enzyme and to determine the dose response of an enzyme to a drug. The fluid pumping and control embodied in this system may be readily integrated with other analytical components (e.g., heating, detection, and informatics) to form the basis for a microscale total analysis system for use in genomics, proteomics, high-throughput screening, and molecular diagnostics.

Reachability analysis has proved to be one of the most effective methods in verifying correctness of communication protocols based on the state transition model. Consequently, many protocol verification tools have been built based on the method of reachability analysis. Nevertheless, it is also well known that state space explosion is the most severe limitation to the applicability of this method. Although researchers in the field have proposed various strategies to relieve this intricate problem when building the tools, a survey and evaluation of these strategies has not been done in the literature. In searching for an appropriate approach to tackling such a problem for a grammar-based validation tool, we have collected and evaluated these relief strategies, and have decided to develop our own from yet another but more systematic approach. The results of our research are now reported in this paper. Essentially, the paper is to serve two purposes: first, to give a survey and evaluation of existing relief strategies; second, to propose a new strategy, called PROVAT (PROtocol VAlidation Testing), which is inspired by the heuristic search techniques in Artificial Intelligence. Preliminary results of incorporating the PROVAT strategy into our validation tool are reviewed in the paper. These results show the empirical evidence of the effectiveness of the PROVAT strategy.

While there have been tremendous efforts to develop the architecture and protocols to support advanced Internet-based services over 3G and 4G networks, IMS is far from being deployed in wide scale. Effort to create an operator controlled signaling infrastructure using IP-based protocols has resulted in a large number of functional components and interactions among those components. Thus, the carriers are trying to explore alternative ways to deploy IMS that will allow them to manage their network in a cost effective manner while offering the value-added services. One of such approaches is self-organization of IMS. The self-organizing IMS can enable the IMS functional components and corresponding nodes to adapt them dynamically based on the features like network load, number of users and available system resources. This chapter introduces such a self-organizing and adaptive IMS architecture, describes the advanced functions and demonstrates the initial results from the prototype test-bed. In particular, we show how all IMS functional components can be merged and split among different nodes as the network demand and environment change without disrupting the ongoing sessions or calls. Although it is too early to conclude the effectiveness of self-organizing IMS, initial results

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Reachabilityanalysis has proved to be one of the