Toward Optimal Replication for Hierarchical Location Management in Wireless Systems

. The location information of users can be replicated at various databases in a hierarchy to improve the efficiency of call lookups at the expense of increase in update and storage cost. In this paper, we systematically investigate this problem and propose two solutions. The first solution has optimal lookup and update cost, but the execution time could be exponential to the number of databases. The second solution makes some assumptions and then uses dynamic programming to tackle this problem. Its execution time is dramatically reduced with the result being less optimal. Finally, to further improve efficiency and reducing storage requirements, we propose the incorporation of clustering techniques. 1 Introduction Establishing a connection in a wireless environment requires the location information of the callee, who may be on the move. While this problem is mostly encountered at the data link or networking layer transparently from the layers above it, applications may also need the lo..

Analysis of the Sensing Properties of a Highly Stable and Reproducible Ozone Gas Sensor Based on Amorphous In-Ga-Zn-O Thin Film

In this study, the sensing properties of an amorphous indium gallium zinc oxide (a-IGZO) thin film at ozone concentrations from 500 to 5 ppm were investigated. The a-IGZO thin film showed very good reproducibility and stability over three test cycles. The ozone concentration of 60–70 ppb also showed a good response. The resistance change (ΔR) and sensitivity (S) were linearly dependent on the ozone concentration. The response time (T90-res), recovery time (T90-rec), and time constant (τ) showed first-order exponential decay with increasing ozone concentration. The resistance–time curve shows that the maximum resistance change rate (dRg/dt) is proportional to the ozone concentration during the adsorption. The results also show that it is better to sense rapidly and stably at a low ozone concentration using a high light intensity. The ozone concentration can be derived from the resistance change, sensitivity, response time, time constant (τ), and first derivative function of resistance. However, the time of the first derivative function of resistance is shorter than other parameters. The results show that a-IGZO thin films and the first-order differentiation method are promising candidates for use as ozone sensors for practical applications

Improving the sensitive and selective of trace amount ozone sensor on Indium-Gallium-Zinc Oxide thin film by ultraviolet irradiation

In this study, we successfully developed amorphous Indium-Gallium-Zinc Oxide (IGZO) thin film under ultraviolet irradiation that demonstrated high stability and high sensitivity in a high-selectivity ozone gas sensor at ppb-level concentrations. The experimental results show that the sensor can detect ozone levels ranging from 55 to 400 ppb with high stability and high repeatability. We also successfully detected concentrations of 10–16 ppb. Ozone changes of 2–5 ppb can be clearly distinguished. Using electron spectroscopy for chemical analysis, we identified the element ratio and ozone detection ability. Higher sensitivity is realized in the presence of oxygen deficiency in metal oxide semiconductors. By controlling ultraviolet intensity, we found the sensitivity of thin film to ozone and nitrogen dioxide to be inversely proportional to light intensity and light intensity can be used to improve gas selectivity. Strong intensity irradiated to sensor causes low sensitivity and high selectivity

Magneto-Optical Characteristics of Streptavidin-Coated Fe3O4@Au Core-Shell Nanoparticles for Potential Applications on Biomedical Assays

Recently, gold-coated magnetic nanoparticles have drawn the interest of researchers due to their unique magneto-plasmonic characteristics. Previous research has found that the magneto-optical Faraday effect of gold-coated magnetic nanoparticles can be effectively enhanced because of the surface plasmon resonance of the gold shell. Furthermore, gold-coated magnetic nanoparticles are ideal for biomedical applications because of their high stability and biocompatibility. In this work, we synthesized Fe3O4@Au core-shell nanoparticles and coated streptavidin (STA) on the surface. Streptavidin is a protein which can selectively bind to biotin with a strong affinity. STA is widely used in biotechnology research including enzyme-linked immunosorbent assay (ELISA), time-resolved immunofluorescence (TRFIA), biosensors, and targeted pharmaceuticals. The Faraday magneto-optical characteristics of the biofunctionalized Fe3O4@Au nanoparticles were measured and studied. We showed that the streptavidin-coated Fe3O4@Au nanoparticles still possessed the enhanced magneto-optical Faraday effect. As a result, the possibility of using biofunctionalized Fe3O4@Au nanoparticles for magneto-optical biomedical assays should be explored

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

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