National Cheng Kung University

About: National Cheng Kung University is a education organization based out in Tainan City, Taiwan. It is known for research contribution in the topics: Population & Thin film. The organization has 49723 authors who have published 69799 publications receiving 1437420 citations. The organization is also known as: NCKU.

Adaptive synchronization of chaotic systems and its application to secure communications

Abstract: This paper addresses the adaptive synchronization problem of the drive–driven type chaotic systems via a scalar transmitted signal. Given certain structural conditions of chaotic systems, an adaptive observer-based driven system is constructed to synchronize the drive system whose dynamics are subjected to the system’s disturbances and/or some unknown parameters. By appropriately selecting the observer gains, the synchronization and stability of the overall systems can be guaranteed by the Lyapunov approach. Two well-known chaotic systems: Rossler-like and Chua’s circuit are considered as illustrative examples to demonstrate the effectiveness of the proposed scheme. Moreover, as an application, the proposed scheme is then applied to a secure communication system whose process consists of two phases: the adaptation phase in which the chaotic transmitter’s disturbances are estimated; and the communication phase in which the information signal is transmitted and then recovered on the basis of the estimated parameters. Simulation results verify the proposed scheme’s success in the communication application.

Mitochondrial fission contributes to mitochondrial dysfunction and insulin resistance in skeletal muscle.

Abstract: Mitochondrial dysfunction in skeletal muscle has been implicated in the development of insulin resistance and type 2 diabetes. Considering the importance of mitochondrial dynamics in mitochondrial and cellular functions, we hypothesized that obesity and excess energy intake shift the balance of mitochondrial dynamics, further contributing to mitochondrial dysfunction and metabolic deterioration in skeletal muscle. First, we revealed that excess palmitate (PA), but not hyperglycemia, hyperinsulinemia, or elevated tumor necrosis factor alpha, induced mitochondrial fragmentation and increased mitochondrion-associated Drp1 and Fis1 in differentiated C2C12 muscle cells. This fragmentation was associated with increased oxidative stress, mitochondrial depolarization, loss of ATP production, and reduced insulin-stimulated glucose uptake. Both genetic and pharmacological inhibition of Drp1 attenuated PA-induced mitochondrial fragmentation, mitochondrial depolarization, and insulin resistance in C2C12 cells. Furthermore, we found smaller and shorter mitochondria and increased mitochondrial fission machinery in the skeletal muscle of mice with genetic obesity and those with diet-induced obesity. Inhibition of mitochondrial fission improved the muscle insulin signaling and systemic insulin sensitivity of obese mice. Our findings indicated that aberrant mitochondrial fission is causally associated with mitochondrial dysfunction and insulin resistance in skeletal muscle. Thus, disruption of mitochondrial dynamics may underlie the pathogenesis of muscle insulin resistance in obesity and type 2 diabetes.

The effects of thickness and operation temperature on ZnO:Al thin film CO gas sensor

Abstract: Al-doped ZnO films were deposited onto SiO 2 /Si substrates by rf magnetron sputtering system as a CO gas sensor. The dependence of the thin film thickness on CO gas sensing properties was investigated, where the film thickness was varied by controlling the deposition time. The structure of the deposited ZnO:Al films was determined by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The CO gas sensing properties were determined by in situ measurement for surface resistance of the thin film as a function of film thickness, different atmosphere, and operation temperature. It was shown that the films were flat and smooth with (0 0 0 1) preferred orientation. The grain size was increased as the film thickness was increased during deposition. Here, the CO gas sensing properties were relative to the structural characteristics where the maximum sensitivity of 61.6% was obtained at 65 nm film thickness for the operation temperature of 400 °C.

Penguin Enhancement and $B \to K\pi$ decays in perturbative QCD

Abstract: We compute the branching ratios of $\stackrel{\ensuremath{\rightarrow}}{B}K\ensuremath{\pi}$ decays in the framework of the perturbative QCD factorization theorem. Decay amplitudes are classified into the topologies of tree, penguin, and annihilation amplitudes, all of which contain both factorizable and nonfactorizable contributions. These contributions are expressed as the convolutions of hard $b$ quark decay amplitudes with universal meson wave functions. It is shown that (1) matrix elements of penguin operators are dynamically enhanced compared to those employed in the factorization assumption, (2) annihilation diagrams are not negligible, contrary to common belief, (3) annihilation diagrams contribute large strong phases, and (4) the uncertainty of the current data of the ratio $R=\mathrm{Br}{(B}_{d}^{0}\ensuremath{\rightarrow}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}})/\mathrm{Br}{(B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}})$ and of $\mathrm{CP}$ asymmetries is too large to give a constraint of the unitarity angle ${\ensuremath{\varphi}}_{3}.$ Assuming ${\ensuremath{\varphi}}_{3}=90\ifmmode^\circ\else\textdegree\fi{}$ which is extracted from the best fit to the data of $R,$ predictions for the branching ratios of the four $\stackrel{\ensuremath{\rightarrow}}{B}K\ensuremath{\pi}$ modes are consistent with data.