Light-directed,spatially addressable oxygen detection in a hydrogel microarray based on phase-based lifetime detection using a digital micromirror device

A digital light modulation system that utilizes a modified commercial digital micromirror device (DMD) projector, which is equipped with a UV LED as a light modulation source, has been developed to spatially direct excitation light toward a hydrogel microarray to detect local oxygen via phase-based phosphorescence lifetime detection. Oxygen-sensitive luminescent microspheres that were encapsulated into the hydrogel microarray were used to detect the local O₂ concentration by sequentially addressing the modulated UV light to each hydrogel microsensing element. Two different hydrogels of alginate and polyethylene glycol diacrylate (PEGDA) were used as the supporting matrices to encapsulate the oxygen-sensitive luminescent microspheres within the hydrogels as microsensing elements. By controlling the illumination pattern on the DMD, the modulated excitation light can be spatially projected to only excite the microsensing element of interest, which can significantly decrease background noise and improve sensitivity. Gaseous oxygen, dissolved oxygen (DO), and glucose sensors that monitored the DO concentrations in the presence of oxygen and oxidase enzymes were characterized using phase-based lifetime detection; the measurements were consistent with the linear Stern–Volmer relationship. In addition, the sensitivity of the alginate supporting matrix was found to be higher than that of PEGDA due to its higher oxygen permeability in the alginate matrix structures. The proposed hydrogel microarray could easily produce large-scale cell-trapped hydrogel microarray. Moreover, the proposed DMD-based digital light modulation system is especially suited to these large-scale cell-trapped hydrogel microarrays in living cell assays.     

The influence of carbon dioxide trading scheme on economic dispatch of generators

This paper aims at probing into the topic of power units’ operation and dispatch based on Carbon Dioxide (CO₂) trading scheme. The trading cost of CO₂ emission is embedded into the traditional economic dispatch model, which will be solved by the New Particle Swarm Optimization (NPSO). By considering the CO₂ trading scheme, the influences of the various strategies for unit’s dispatch are simulated and analyzed in this paper. The proposed method, NPSO is developed in such a way that PSO with Constriction Factor (PSO-CF) algorithm is applied as a based level search. NPSO introduces two operators, “Random Particles” and “Fine-Tuning” into the PSO-CF algorithm to improve the drawback of searching global optimum and make the search method more efficient at the end of search. The efficiency and ability of NPSO is demonstrated by the six generating units. Simulation results indicated that reasonable solutions provide a practical and flexible framework for power sectors. They can be also used for generating alternatives and thus help decision makers to obtain the goals of minimal operation cost under their desired emission’s policies.     

Lidar ratio and depolarization ratio for cirrus clouds

We report on studies of the lidar and the depolarization ratios for cirrus clouds. The optical depth and effective lidar ratio are derived from the transmission of clouds, which is determined by comparing the backscattering signals at the cloud base and cloud top. The lidar signals were fitted to a background atmospheric density profile outside the cloud region to warrant the linear response of the return signals with the scattering media. An average lidar ratio, 29 +/- 12 sr, has been found for all clouds measured in 1999 and 2000. The height and temperature dependences ofthe lidar ratio, the optical depth, and the depolarization ratio were investigated and compared with results of LITE and PROBE. Cirrus clouds detected near the tropopause are usually optically thin and mostly subvisual. Clouds with the largest optical depths were found near 12 km with a temperature of approximately -55 degrees C. The multiple-scattering effect is considered for clouds with high optical depths, and this effect lowers the lidar ratios compared with a single-scattering condition. Lidar ratios are in the 20-40 range for clouds at heights of 12.5-15 km and are smaller than approximately 30 in height above 15 km. Clouds are usually optically thin for temperatures below approximately -65 degrees C, and in this region the optical depth tends to decrease with height. The depolarization ratio is found to increase with a height at 11-15 km and smaller than 0.3 above 16 km. The variation in the depolarization ratio with the lidar ratio was also reported. The lidar and depolarization ratios were discussed in terms of the types of hexagonal ice crystals.     

Asymptotic distribution of the number of isolated nodes in wireless ad hoc networks with Bernoulli nodes

Nodes in wireless ad hoc networks may become inactive or unavailable due to, for example, internal breakdown or being in the sleeping state. The inactive nodes cannot take part in routing/relaying, and thus may affect the connectivity. A wireless ad hoc network containing inactive nodes is then said to be connected, if each inactive node is adjacent to at least one active node and all active nodes form a connected network. This paper is the first installment of our probabilistic study of the connectivity of wireless ad hoc networks containing inactive nodes. We assume that the wireless ad hoc network consists of n nodes which are distributed independently and uniformly in a unit-area disk, and are active (or available) independently with probability p for some constant 0

相似文献   

Platform-Based MPEG-4 SOC Design for Video Communications

An MPEG-4 video coding SOC design is presented in this paper. We adopt platform-based architecture with an embedded RISC core and efficient memory organization. A motion estimator supporting predictive diamond search and spiral full search is implemented for compromise between compression performance and design cost. The proposed data reuse scheme reduces required memory access bandwidth. For texture coding path, an interleaving DCT/IDCT scheduling with substructure sharing technique is proposed. Several key modules are integrated into an efficient platform in hardware/software co-design fashion. The cost-efficient video encoder SOC consumes 256.8 mW at 40 MHz and achieves real-time encoding of 30 CIF (352×288) frames per second. Yung-Chi Chang was born in Kaohsiung, Taiwan, R.O.C., in 1975. He received the B.S. and M.S. degrees from the Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan, R.O.C., in 1998 and 2000, respectively, where he is currently pursuing the Ph.D. degree in the Graduate Institute of Electrical Engineering. His research interests include video coding algorithms and VLSI architectures for image/video processing. Wei-Min Chao was born in Taoyuan, Taiwan, R.O.C., in 1977. He received the B.S. and M.S. degrees from the Department of Electronics Engineering, National Taiwan University in 2000 and 2002 separately. His research interests include video coding algorithms and VLSI architecture for image and video processing. Chih-Wei Hsu was born in Taipei, Taiwan, in 1979. He received the B.S.E.E and M.S.E.E degrees from National Taiwan University (NTU), Taipei, in 2001 and 2003, respectively. He joined MediaTek, Inc., Hsinchu, Taiwan, in 2003, where he develops integrated circuits related to multimedia systems and optical storage devices. His research interests include object tracking, video coding, baseband signal processing, and VLSI design. Liang-Gee Chen was born in Yun-Lin, Taiwan, in 1956. He received the B.S., M.S., and Ph.D. degrees in electrical engineering from National Cheng Kung University, Tainan, Taiwan, in 1979, 1981, and 1986, respectively. He was an Instructor (1981-1986), and an Associate Professor (1986-1988) in the Department of Electrical Engineering, National Cheng Kung University. In the military service during 1987 to 1988, he was an Associate Professor in the Institute of Resource Management, Defense Management College. In 1988, he joined the Department of Electrical Engineering, National Taiwan University. During 1993 to 1994 he was a Visiting Consultant of DSP Research Department, AT & T Bell Lab, Murray Hill. In 1997, he was a visiting scholar of the Department of Electrical Engineering, University of Washington, Seattle. During 2001 to 2004, he was the first director of the Graduate Institute of Electronics Engineering (GIEE) in National Taiwan University (NTU). Currently, he is a Professor of the Department of Electrical Engineering and GIEE in NTU, Taipei, Taiwan. He is also the director of the Electronics Research and Service Organization in Industrial Technology Research Institute, Hsinchu, Taiwan. His current research interests are DSP architecture design, video processor design, and video coding systems. Dr. Chen has served as an Associate Editor of IEEE Transactions on Circuits and Systems for Video Technology since 1996, as Associate Editor of IEEE Transactions on VLSI Systems since 1999, and as Associate Editor of IEEE Transactions on Circuits and Systems II since 2000. He has been the Associate Editor of the Journal of Circuits, Systems, and Signal Processing since 1999, and a Guest Editor for the Journal of Video Signal Processing Systems. He is also the Associate Editor of the Proceedings of the IEEE. He was the General Chairman of the 7th VLSI Design/CAD Symposium in 1995 and of the 1999 IEEE Workshop on Signal Processing Systems: Design and Implementation. He is the Past-Chair of Taipei Chapter of IEEE Circuits and Systems (CAS) Society, and is a member of the IEEE CAS Technical Committee of VLSI Systems and Applications, the Technical Committee of Visual Signal Processing and Communications, and the IEEE Signal Processing Technical Committee of Design and Implementation of SP Systems. He is the Chair-Elect of the IEEE CAS Technical Committee on Multimedia Systems and Applications. During 2001--2002, he served as a Distinguished Lecturer of the IEEE CAS Society. He received the Best Paper Award from the R.O.C. Computer Society in 1990 and 1994. Annually from 1991 to 1999, he received Long-Term (Acer) Paper Awards. In 1992, he received the Best Paper Award of the 1992 Asia-Pacific Conference on circuits and systems in the VLSI design track. In 1993, he received the Annual Paper Award of the Chinese Engineer Society. In 1996 and 2000, he received the Outstanding Research Award from the National Science Council, and in 2000, the Dragon Excellence Award from Acer. He is a member of Phi Tan Phi.     

Optimization of active region for 1.3-µm GalnAsP compressive-strain multiple-quantum-well ridge waveguide laser diodes

We report on the optimization of Ga_0.27In_0.73As_0.67P_0.33/Ga_0.11In_0.89As_0.24P_0.76 compressive-strain multiple-quantum-well (CS-MQW) grown by low-pressure metalorganic chemical vapor deposition for 1.3-μm ridge-waveguide laser diodes (LDs). The structural and optical properties are characterized by doublecrystal x-ray diffraction and photoluminescence (PL) measurements, respectively. The optimum thicknesses of the well, barrier, and waveguide layer of the active region are 4 nm, 10 nm, and 100 nm, respectively. The GaInAsP/GaInAsP CS-MQW as-cleaved LDs with the optimum active region, a 3.5-μm-width ridge, and a 900-μm-cavity length exhibit the threshold current density of 1.09 kA/cm², a differential quantum efficiency of 30%, a characteristic temperature of 60 K, a maximum operating temperature up to 75°C, and a redshift rate of 0.30 nm/°C.     

A Simple Decomposition Method for Support Vector Machines

The decomposition method is currently one of the major methods for solving support vector machines. An important issue of this method is the selection of working sets. In this paper through the design of decomposition methods for bound-constrained SVM formulations we demonstrate that the working set selection is not a trivial task. Then from the experimental analysis we propose a simple selection of the working set which leads to faster convergences for difficult cases. Numerical experiments on different types of problems are conducted to demonstrate the viability of the proposed method.     

Resolution improvement with dispersion manipulation and a retrieval algorithm in optical coherence tomography

We propose and demonstrate what is to our knowledge a novel technique of improving the spatial resolution of an optical coherence tomography (OCT) system given a non-Gaussian light source spectrum. By using dispersive materials in the reference arm of the OCT system, the resultant dispersion variation led to a full-width at half maximum (FWHM) of the interference fringe envelope smaller than the Fourier transform-limited value of a Gaussian spectral shape with the same spectral FWHM, at the expense of significant tails. The effects of the tails, which would blur the OCT images, were tremendously reduced with a retrieval algorithm. Simulation results and processed OCT scanning images have shown the capability of the proposed technique.     

A fluorescent carbazole derivative: high sensitivity for quadruplex DNA

We have synthesized a novel molecule, 3,6-bis(1-methyl-4-vinylpyridium)carbazole diiodide (BMVC), for recognizing specific quadruplex structures, particularly the quadruplex of human telomeric sequence d(T(2)AG(3))(4). The fluorescence intensity of the BMVC molecule increases from 1 to almost 2 orders of magnitude upon interacting with various DNAs. At a concentration of BMVC of 10 microM, fluorescence bands with different colors of BMVC in electrophoresis gels of various DNAs can be observed. The fluorescence of BMVC can be used to discriminate between duplex and quadruplex DNAs. At the low concentration of 0.1 microM BMVC in prestained gels, the fluorescence is observed in the presence of quadruplexes with anti-anti-anti-anti and anti-anti-syn-syn arrangements. However, no fluorescence band is detected upon interacting with duplexes and quadruplexes with anti-syn-anti-syn arrangement. Moreover, the sensitivity assays show that as little as 0.2 pmol of quadruplex of d(T(2)AG(3))(4) can be revealed by BMVC.     

A Unified Analytic Framework Based on Minimum Scan Statistics for Wireless Ad Hoc and Sensor Networks

Due to limitations on transmission power of wireless devices, areas with sparse nodes are decisive to some extreme properties of network topology. In this paper, we assume wireless ad hoc and sensor networks are represented by uniform point processes or Poisson point processes. Asymptotic analyses based on minimum scan statistics are given for some crucial network properties, including coverage of wireless sensor networks, connectivity of wireless ad hoc networks, the largest edge length of geometric structures, and local-minimum-free geographic routing protocols. We derive explicit formulas of minimum scan statistics. By taking the transmission radius as a major parameter, our results are applied to various network problems. This work offers a unified approach to solve various problems and reveals the evolution of network topology. In addition, boundary effects are thoroughly handled.