A Fast Feature-based Dimension Reduction Algorithm for Kernel Classifiers

This paper presents a novel dimension reduction algorithm for kernel based classification. In the feature space, the proposed algorithm maximizes the ratio of the squared between-class distance and the sum of the within-class variances of the training samples for a given reduced dimension. This algorithm has lower complexity than the recently reported kernel dimension reduction (KDR) for supervised learning. We conducted several simulations with large training datasets, which demonstrate that the proposed algorithm has similar performance or is marginally better compared with KDR whilst having the advantage of computational efficiency. Further, we applied the proposed dimension reduction algorithm to face recognition in which the number of training samples is very small. This proposed face recognition approach based on the new algorithm outperforms the eigenface approach based on the principal component analysis (PCA), when the training data is complete, that is, representative of the whole dataset.     

Fluorescent liposomes as contrast agents for in vivo optical imaging of edemas in mice

This study assesses if specially designed fluorescent liposomes can be used as contrast agent for near-infrared fluorescence (NIRF) optical imaging of cultured macrophages in vitro and for NIRF imaging of inflammatory processes, like edema, in an in vivo mouse model. Fluorescent liposomes are prepared by the film hydration and extrusion method using cholesterol, L-phosphatidylcholine, and the NIR fluorescent dye DY-676-C(18) ester. Photon correlation spectroscopy and flow cytometry reveal that fluorescent liposomes are structurally stable for up to 133 days. Distinct uptake/labeling of cultured murine J774 macrophages is demonstrated by confocal laser scanning microscopy (CLSM), flow cytometry, and macroscopic NIRF imaging system at wavelengths >670 nm. Moreover, CLSM analysis reveals fluorescence signals within intracellular compartments. Ear edema is induced in mice (n = 16) by subcutaneous injection of zymosan A. Whole-body NIRF imaging is performed after intravenous injection (0-24 h) of fluorescent liposomes (55 nmol dye per kg body weight). Distinctly higher fluorescence intensities (1613.6 +/- 61.7 a.u.) are detected at inflamed areas of diseased mice as compared to controls (892.8 +/- 19.4 a.u.). Furthermore, cell isolated from ear lavage reveals the presence of labeled F4/80 positive tissue macrophages. Taken together, the results indicate both that mouse macrophages labeled with fluorescent liposomes can be detected in vitro with fluoro-optical methods and that in vivo optical imaging of inflammatory processes with fluorescent liposomes as contrast agent is feasible. Possibly, early stages of other inflammatory diseases could also be detected by the proposed diagnostic tool in the long term.     

Analysis of extracellular matrix production in artificial cartilage constructs by histology, immunocytochemistry, mass spectrometry, and NMR spectroscopy

Artificial cartilage constructs based on primary porcine chondrocytes embedded in agarose gel were cultivated for six weeks under static, free swelling conditions. Standard biochemical assays, immunocytochemical staining methods, MALDI-TOF mass spectrometry, and non-invasive 13C solid-state NMR spectroscopy were used to assess cell proliferation, chondrocyte metabolism, extracellular matrix composition, matrix production, and the nanoarchitecture of the macromolecules in the constructs. In particular the production of sulphated glycosaminoglycans such as chondroitin sulphate was investigated quantitatively. Standard methods such as histological and immunocytochemical tools as well as spectrophotometric assays indicated the production of extracellular matrix in the artificial cartilage constructs. In addition, MALDI-TOF mass spectrometric data allowed to clearly identify the production of chondroitin sulphate in the tissue engineered cartilage. While all these methods require invasive sample treatment, 13C NMR spectroscopy allows to study the composition of the artificial cartilage constructs without previous manipulations. Though lower in sensitivity, 13C NMR spectra clearly showed the presence of chondroitin sulphate in the constructs. To increase the sensitivity of the NMR method, a culture medium that contained uniformly 13C labelled glucose but no sodium pyruvate or L-glutamine was used. Thus, further insights into the chondrocyte metabolism ex vivo are possible. Therefore, MALDI-TOF mass spectrometry and 13C solid-state NMR are useful experimental techniques that can assist the quantitative evaluation and quality control of artificially engineered tissues.     

Load control of a wind-hydrogen stand-alone power system

A new generation of load controllers enable stand-alone power systems (SAPS) to use one or many standard (grid connected) wind turbines. The controllers use fuzzy logic software algorithms. The strategy is to use the control loads to balance the flow of active power in the system and hence control system frequency. The dynamic supply of reactive power by a synchronous compensator maintains the system voltage within the limits specified in EN50160. The resistive controller loads produce a certain amount of heat that is exchanged down to the end user (hot water). It was decided to investigate the implementation of a hydrogen subsystem into the SAPS that can work in parallel with the Distributed Intelligent Load Controller (DILC). The hydrogen subsystem can then function as energy storage on long-term basis and an active load controller on short-term basis.     

Minimizing Energy for Wireless Web Access with Bounded Slowdown

On many battery-powered mobile computing devices, the wireless network is a significant contributor to the total energy consumption. In this paper, we investigate the interaction between energy-saving protocols and TCP performance for Web-like transfers. We show that the popular IEEE 802.11 power-saving mode (PSM), a static protocol, can harm performance by increasing fast round trip times (RTTs) to 100 ms; and that under typical Web browsing workloads, current implementations will unnecessarily spend energy waking up during long idle periods. To overcome these problems, we present the Bounded-Slowdown (BSD) protocol, a PSM that dynamically adapts to network activity. BSD is an optimal solution to the problem of minimizing energy consumption while guaranteeing that a connections RTT does not increase by more than a factor p over its base RTT, where p is a protocol parameter that exposes the trade-off between minimizing energy and reducing latency. We present several trace-driven simulation results that show that, compared to a static PSM, the Bounded-Slowdown protocol reduces average Web page retrieval times by 5–64%, while simultaneously reducing energy consumption by 1–14% (and by 13× compared to no power management).     

Selection and characterization of PCB-binding DNA aptamers

Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) that resist natural degradation and bioaccumulate in nature. Combined with their toxicity, this leads them to cause cancer and other health hazards. Thus, there is a vital need for rapid and sensitive methods to detect PCB residues in food and in the environment. In this study, PCB-binding DNA aptamers were developed using PCB72 and PCB106 as targets for aptamer selection. Aptamers are synthetic DNA recognition elements which form unique conformations that enable them to bind specifically to their targets. Using in vitro selection techniques and fluorometry, an aptamer that binds with nanomolar affinity to both the PCBs has been developed. It displayed high selectivity to the original target congeners and limited affinity toward other PCB congeners (105, 118, 153, and 169), suggesting general specificity for the basic PCB skeleton with varying affinities for different congeners. This aptamer provides a basis for constructing an affordable, sensitive, and high-throughput assay for the detection of PCBs in food and environmental samples and offers a promising alternative to existing methods of PCB quantitation. This study therefore advances aptamer technology by targeting one of the highly sought-after POPs, for the first time ever recorded.     

Synthesis,Catalytic Activity in Oxidation Reactions,and Recyclability of Stable Polyoxometalate‐Centred Dendrimers

Nine‐ and 27‐armed dendrimers with a peroxophosphotungstate core were synthesized by an ionic‐bonding approach and used as air‐stable, recoverable catalysts for oxidation reactions using hydrogen peroxide.