Browsing by Issue Date, starting with "2012-02-01"

Now showing 1 - 20 of 37413

Functional Characterization of Glycine N-Methyltransferase and Its Interactive Protein DEPDC6/DEPTOR in Hepatocellular Carcinoma
(2012-02-01)
Yen, Chia-Hung
;
Lu, Yao-Cheng
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Li, Chung-Hsien
;
Lee, Cheng-Ming
;
Chen, Chia-Yen
Glycine N-methyltransferase (GNMT) is a tumor suppressor for hepatocellular carcinoma (HCC). High rates of Gnmt knockout mice developed HCC. Epigenetic alteration and dysregulation of several pathways including wingless-type MMTV integration site (Wnt), mitogen-activated protein kinase (MAPK) and Janus kinase and signal transducer and activator of transcription (JAK-STAT) are associated with HCC development in Gnmt knockout mice. We hypothesized that GNMT may regulate signal transduction through interacting with other proteins directly. In this report, we identified a mammalian target of rapamycin (mTOR) inhibitor (DEP domain containing MTOR-interacting protein (DEPDC6/DEPTOR)) as a GNMT-binding protein by using yeast two-hybrid screening. Fluorescence resonance energy transfer assay demonstrated that the C-terminal half of GNMT interact with the PSD-95/DIg1/ZO-1 (PDZ) domain of DEPDC6/DEPTOR. Immunohistochemical staining showed that 27.5% (14/51) of HCC patients had higher expression levels of DEPDC6/DEPTOR in the tumorous tissues than in tumor-adjacent tissues, especially among HCC patients with hepatitis B viral infection (odds ratio 10.3, 95% confidence interval (CI) 1.05-11.3) or patients with poor prognosis (death hazard ratio 4.51, 95% CI 1.60-12.7). In terms of molecular mechanism, knockdown of DEPDC6/DEPTOR expression in HuH-7 cells caused S6K and 4E-BP activation, but suppressed Akt. Overexpression of DEPDC6/DEPTOR activated Akt and increased survival of HCC cells. Overexpression of GNMT caused activation of mTOR/raptor downstream signaling and delayed G2/M cell cycle progression, which altogether resulted in cellular senescence. Furthermore, GNMT reduced proliferation of HuH-7 cells and sensitized them to rapamycin treatment both in vitro and in vivo. In conclusion, GNMT regulates HOC growth in part through interacting with DEPDC6/DEPTOR and modulating mTOR/raptor signaling pathway. Both GNMT and DEPDC6/DEPTOR are potential targets for developing therapeutics for HCC. Online address: http://www.molmed.org doi: 10.2119/molmed.2011.00331
A New Negative Liquid Crystal Lens With Multiple Ring Electrodes in Unequal Widths
(2012-02-01)
Chao, P. C. -P.
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Kao, Y. -Y.
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Hsu, C. -J.
;
電機工程學系
;
Department of Electrical and Computer Engineering
This study is dedicated to the design of a new negative liquid crystal (LC) lens with multiple ring electrodes in unequal widths. The number and widths of the multiple ring electrodes are designed to offer online tunability on focusing length by predetermined individual electrode voltages. This aims to render a smooth refraction index distribution that mimics well a divergent lens based on the theory of a gradient refraction index (GRIN) lens. Finally, the proposed negative LC lens is fabricated with the capability of realizing different focus lengths in a relatively large aperture of 5 mm and a thickness of 0.7 mm. Experiments are conducted to verify expected light-diverging performance. The effective focus length (EFL) is measured based on interference patterns. It is shown that the proposed negative LC lens is able to realize light-divergent effects with an EFL as short as -357.9 mm.
A modal sensor integrated circular cylindrical wedge wave ultrasonic motor
(2012-02-01)
Yu, Tai-Ho
;
Yin, Ching-Chung
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機械工程學系
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Department of Mechanical Engineering
This study investigates a new circular cylindrical wedge wave ultrasonic motor (WW-USM) integrated with modal sensors. The presented motor is driven by continuous wedge waves of the fundamental modes with an integer circumferential number. In this design, the constructive interference of two equal-intensity standing waves actuated by two comb transducers generates a traveling wedge wave. Dual-phase electrodes were parallel to the axis placed on a piezoelectric (PZT) tube at a distance of 1/4 wavelength. Two orthogonal sinusoidal signals at the resonant frequency of designated flexural mode exerting on the electrodes have the WW-USM operate in bidirectional rotation. The base height of the stator was appropriately tuned to achieve an excellent modal separation from other vibration modes. A modal sensor on the border of the PZT tube was designed to detect the dynamic characteristics of the WW-USM and to improve the performance. The wedge wave motor has a flexible mechanical performance between the angular speed and output torque. Varying the contact position of the rotor on the inclined surface of the stator may exchange the angular speed for torque output. No further modification of the entire motor structure is needed. The prototype WW-USM driven by the flexural mode F(1, 4) under 1 N static preload was operated by an AC voltage of 400 V-pp at the frequency of 36.605 kHz. The maximum values of angular speed, output torque, and electromechanical transduction efficiency are 225 rpm, 15.736 mN m, and 16.22%, respectively. (C) 2011 Elsevier B.V. All rights reserved.
A new force-directed graph drawing method based on edge-edge repulsion
(2012-02-01)
Lin, Chun-Cheng
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Yen, Hsu-Chun
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工業工程與管理學系
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Department of Industrial Engineering and Management
The conventional force-directed methods for drawing undirected graphs are based on either vertex-vertex repulsion or vertex-edge repulsion. In this paper, we propose a new force-directed method based on edge-edge repulsion to draw graphs, In our framework, edges are modelled as charged springs, and a final drawing can be generated by adjusting positions of vertices according to spring forces and the repulsive forces, derived from potential fields, among edges. Different from the previous methods, our new framework has the advantage of overcoming the problem of zero angular resolution, guaranteeing the absence of any overlapping of edges incident to the common vertex. Given graph layouts probably generated by previous algorithms as the inputs to our algorithm, experimental results reveal that our approach produces promising drawings not only preserving the original properties of a high degree of symmetry and uniform edge length, but also preventing zero angular resolution and usually having larger average angular resolution. However, it should be noted that exhibiting a higher degree of symmetry and larger average angular resolution does not come without a price, as the new approach might result in the increase in undesirable overlapping of vertices as some of our experimental results indicate. To ease the problem of node overlapping, we also consider a hybrid approach which takes into account both edge-edge and vertex-vertex repulsive forces in drawing a graph. (C) 2011 Elsevier Ltd. All rights reserved.
High rotation number effect on heat transfer in a trailing edge channel with tapered ribs
(2012-02-01)
Liu, Yao-Hsien
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Huh, Michael
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Han, Je-Chin
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機械工程學系
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Department of Mechanical Engineering
Detailed heat transfer measurements were conducted in a wedge-shaped channel with lateral flow ejection, which is commonly found in the trailing edge cooling cavities of the gas turbine blade. Tapered ribs were applied on the leading and trailing surfaces to enhance heat transfer. Rib spacing (P/e(max)) was 8 and the ratio of rib height to channel height (e/H) was 0.125. The inlet Reynolds number ranged from 10,000 to 40,000. At the highest rotational speed of 400 rpm, the inlet rotation number was 0.8. Effect of flow ejection on pressure drop, mass flow rate and heat transfer distribution were investigated. Results show that the configuration of this tapered rib enhances heat transfer on the ribbed surface but ejection still has pronounced effects on heat transfer distribution. The experimental data has been correlated with the high rotation number and high buoyancy parameter in ranges similar to industry applications. (C) 2011 Elsevier Inc. All rights reserved.
A hierarchical multiple-model approach for detection and isolation of robotic actuator faults
(2012-02-01)
Hsiao, Tesheng
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Weng, Mao-Chiao
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電機工程學系
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Department of Electrical and Computer Engineering
Modern robotic systems perform elaborate tasks in complicated environments and have close interactions with humans. Therefore fault detection and isolation (FDI) schemes must be carefully designed and implemented on robotic systems in order to guarantee safe and reliable operations. In this paper, we propose a hierarchical multiple-model FDI (HMM-FDI) scheme to detect and isolate actuator faults of robot manipulators. The proposed algorithm performs FDI in stages and refines the associated model set at each stage. Consequently only a small number of models are required to detect and isolate various types of unexpected actuator faults, including abrupt faults, incipient faults, and simultaneous faults. In addition, the computational load is alleviated due to the reduced-sized model set. The relation between the fault detection stage of the HMM-FDI scheme and the likelihood ratio test is explicitly revealed and theoretical upper bounds of the false alarm and missed detection probabilities are evaluated. Then we conduct experiments to demonstrate the ability of the HMM-FDI scheme in successful and immediate detection and isolation of actuator faults. (C) 2011 Elsevier B.V. All rights reserved.
Bottom Electrode Modification of ZrO2 Resistive Switching Memory Device with Au Nanodots
(2012-02-01)
Lee, Dai-Ying
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Yao, I-Chuan
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Tseng, Tseung-Yuen
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材料科學與工程學系
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電子工程學系及電子研究所
The resistive switching properties of the ZrO2 memory devices with bottom electrode modification by using Au nanodots are investigated in this study. The regular arrays of Au nanodots are fabricated on Pt bottom electrode by nanosphere lithography. Due to the tip of the Au nanodots on the Pt bottom electrode, it causes the higher electric field within the ZrO2 film above the nanodots due to reduced effective film thickness and induces the localized conducting filaments easily. The operation parameters' variation for switching devices is, therefore, suppressed with lower operation voltage and resistance ratio. Long retention time (> 10(6) s) and stubborn nondestructive readout test (> 10(4) s) at room temperature and 150 degrees C are also demonstrated in this device. (C) 2012 The Japan Society of Applied Physics
自我對準之頂閘極薄膜電晶體及其製法
(2012-02-01)
冉曉雯
;
陳蔚宗
;
周政偉
;
蔡娟娟
提供一種自我對準之頂閘極薄膜電晶體，係包括：表面依序形成有氧化物半導體層、介電層及金屬層的基板，其中，該氧化物半導體層具有外露出該介電層及金屬層之第一連接區及第二連接區，且該第一連接區及第二連接區係經加熱處理或紫外光波長之輻射照射，而具有導體之性能；以及形成於該基板上之源極與汲極，係分別連接該第一連接區及第二連接區。本發明之自我對準之頂閘極薄膜電晶體的製法無須經由離子摻雜佈植製程即可降低第一連接區及第二連接區之接觸電阻，大幅簡化製程複雜度與要求仍可精準定位源極與汲極，提升元件特性。
Total completion time minimization in two-machine flow shop scheduling problems with a fixed job sequence
(2012-02-01)
Hwang, F. J.
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Kovalyov, M. Y.
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Lin, B. M. T.
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
This paper addresses scheduling n jobs in a two-machine flow shop to minimize the total completion time, subject to the condition that the jobs are processed in the same given sequence on both machines. A new concept of optimal schedule block is introduced, and polynomial time dynamic programming algorithms employing this concept are derived for two specific problems. In the first problem, the machine-2 processing time of a job is a step increasing function of its waiting time between the machines, and a decision about machine-1 idle time insertion has to be made. This problem is solved in O(n(2)) time. In the second problem, the jobs are processed in batches and each batch is preceded by a machine-dependent setup time. An O(n(5)) algorithm is developed to find an optimal batching decision. (C) 2011 Elsevier B.V. All rights reserved.
Design tables and charts for uniform and non-uniform tuned liquid column dampers in harmonic pitching motion
(2012-02-01)
Wu, Jong-Cheng
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Wang, Yen-Po
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Chen, Yi-Hsuan
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土木工程學系
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Department of Civil Engineering
In the first part of the paper, the optimal design parameters for tuned liquid column dampers (TLCD) in harmonic pitching motion were investigated. The configurations in design tables include uniform and non-uniform TLCDs with cross-sectional ratios of 0.3, 0.6, 1, 2 and 3 for the design in different situations. A closed-form solution of the structural response was used for performing numerical optimization. The results from optimization indicate that the optimal structural response always occurs when the two resonant peaks along the frequency axis are equal. The optimal frequency tuning ratio, optimal head loss coefficient, the corresponding response and other useful quantities are constructed in design tables as a guideline for practitioners. As the value of the head loss coefficient is only available through experiments, in the second part of the paper, the prediction of head loss coefficients in the form of a design chart are proposed based on a series of large scale tests in pitching base motions, aiming to ease the predicament of lacking the information of head loss for those who wishes to make designs without going through experimentation. A large extent of TLCDs with cross-sectional ratios of 0.3, 0.6, 1, 2 and 3 and orifice blocking ratios ranging from 0%, 20%, 40%, 60% to 80% were inspected by means of a closed-form solution under harmonic base motion for identification. For the convenience of practical use, the corresponding empirical formulas for predicting head loss coefficients of TLCDs in relation to the cross-sectional ratio and the orifice blocking ratio were also proposed. For supplemental information to horizontal base motion, the relation of head loss values versus blocking ratios and the corresponding empirical formulas were also presented in the end.
適用於縮短式ＢＣＨ碼或Ｒｅｅｄ－Ｓｏｌｏｍｏｎ碼之解碼方法及裝置
(2012-02-01)
張錫嘉
;
吳昭逸
;
廖彥欽
本發明提出一種BCH碼與Reed－Solomon碼的解碼方法與裝置。其採用修改後的Berlekamp－Massey演算法來進行解碼，藉由將其中的錯誤位置多項式重新定義為逆向錯誤位置多項式，解碼器之效率得以提升，解碼過程之運算更可由共用之可重組式模組來加以實現。解碼器並以多套可重組式模組構成解碼器之架構，提供不同平行度之平行運算，以滿足解碼器在不同應用下之解碼速率需求。
Wafer-level Cu-Cu bonding technology
(2012-02-01)
Tang, Ya-Sheng
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Chang, Yao-Jen
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Chen, Kuan-Neng
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Semiconductor industry currently utilizes copper wafer bonding as one of key technologies for 3D integration. This review paper describes both science and technology of copper wafer bonding with regard to present applications. The classification of Cu bonding, bonding mechanisms, process developments, its microstructure evolution, as well as other characterizations are reviewed. Researches about patterned Cu bonding, future prospects, and 3D integration using Cu bonding are discussed in this paper. (C) 2011 Elsevier Ltd. All rights reserved.
BLOGGING TO LEARN: BECOMING EFL ACADEMIC WRITERS THROUGH COLLABORATIVE DIALOGUES
(2012-02-01)
Sun, Yu-Chih
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Chang, Yu-jung
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英語教學研究所
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Institute of Teaching English to speakers of other Languages
This study examines how blogs and their interactive and collaborative features help academically-advanced graduate students process academic writing knowledge and make sense of their writer identity. Seven graduate students undertaking Master's level study in TESOL and Linguistics participated. The research questions are: (a) What kinds of writing-related topics do students blog about? (b) How do students' collaborative dialogues on blogs help them process and reconstruct knowledge about academic writing? (c) How do students' collaborative dialogues on blogs facilitate their negotiation of academic identities and construction of authorship? Open-coding and content analysis were conducted to inductively identify salient themes and patterns regarding students' learning and perception of their writer identities. The results suggest that the blog activity not only encourages students to actively and reflectively engage in knowledge sharing, knowledge generation, and the development of numerous strategies to cope with difficulties encountered in the learning process. Blogs also endow students with a sense of authorship as the writers of blog entries and, at the same time, provide a space for them to sort out what being an author entails, their purposes of writing, and their authority in writing.
Cellular uptake and phototoxicity of surface-modified fluorescent nanodiamonds
(2012-02-01)
Weng, Mao-Feng
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Chang, Bo-Jui
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Chiang, Su-Yu
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Wang, Niann-Shiah
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Niu, Huan
Bioconjugated fluorescent nanodiamonds (FNDs) show potential for effectively targeted imaging and the enhanced photokilling of cancer cells. In this study, we investigated the mechanisms involved in the cellular uptake of surface-modified 140 nm FNDs and evaluated their cytotoxicity and phototoxicity following particle internalization. Through an analysis of flow cytometry, the internalized FND-Tf and FND-NH2 particles reached their respective saturation values, with half-life times of approximately 0.8 h and 1.4 h. The determination indicated that the receptor-mediated endocytosis of FND-Tf particles was highly effective and nearly twice as efficient as the endocytic process of FND-NH2 particles mainly through surface electrostatic interactions. The cytotoxicity of internalized particles was evaluated using the MU assay, indicating that at saturation concentrations, the rate of proliferation of FND-treated cells decreases to less than half that of untreated cells. An examination of the phototoxicity of internalized FND-Tf particles under irradiation using a 532 nm laser revealed that the FND-treated cells could be killed using less than half the energy required for untreated cells. The enhanced cellular killing was attributed to FND particles converting light to thermal energy, with the support of Raman spectra of nanodiamond clusters that showed an increase in particle temperature under irradiation. Our results demonstrated that bioconjugated FNDs could be highly effective in the targeting of cancer cells for fluorescence imaging and photokilling with a minimum of collateral cell damage. (C) 2011 Elsevier B.V. All rights reserved.
Spectral dependence of transient reflectance in a ZnO epitaxial film at room temperature
(2012-02-01)
Ou, P-C
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Lin, J-H
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Hsieh, W-F
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光電工程學系
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Department of Photonics
We demonstrated the spectral dependence of time-resolved reflectance in a ZnO epitaxial film at room temperature. The ultrafast thermalization time increases as increasing the excitation photon energy accompanied with the hot phonon effect. The obtained recovery time of renormalized bandgap, associated with the nonradiative decay or the free exciton formation, is independent of photon energy. Based on a theoretical model to calculate the carrier-induced change of refractive index in ZnO, the spectral dependent transient reflectance can be successfully analyzed as a result of combined effects of band-filling (BF) and bandgap renormalization (BGR). The measured transient reflectance decreases with decreasing the photon energy for excitation above the bandgap states revealing the significance of competition of the BF and BGR effects.
A BODIPY-Based Highly Selective Fluorescent Chemosensor for Hg2+ Ions and Its Application in Living Cell Imaging
(2012-02-01)
Vedamalai, Mani
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Wu, Shu-Pao
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應用化學系
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Department of Applied Chemistry
A new borondipyrromethene (BODIPY) derivative (FS1) containing two triazole units exhibits an enhanced fluorescence in the presence of Hg2+ ions and a high selectivity for Hg2+ ions over competing metal ions in methanol: Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ produced only minor changes in the fluorescence of FS1. The apparent dissociation constant (Kd) of FS1Hg2+ was found to be 62 mu M. Moreover, fluorescence microscopy experiments showed that FS1 can be used as a fluorescent probe for detecting Hg2+ ions in living cells.
Multi-server machine repair model with standbys and synchronous multiple vacation
(2012-02-01)
Ke, Jau-Chuan
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Wu, Chia-Huang
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工業工程與管理學系
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Department of Industrial Engineering and Management
This paper investigates a machine repair problem with homogeneous machines and standbys available, in which multiple technicians are responsible for supervising these machines and operate a (R, V, K) synchronous vacation policy. With such a policy, if any V idle technicians exist in the system, these V (V < R) technicians would take a synchronous vacation. Upon returning from vacation, they would take another vacation if there is no broken machine waiting in the queue. This pattern continues until at least one failed machine arrives. It is assumed that the number of teams/groups on vacation is less than or equal to K (0 <= KV < R). The matrix analytical method is employed to obtain a steady-state probability and the closed-form expression of the system performance measures. Efficient approaches are performed to deal with the optimization problem of the discrete/continuous variables while maintaining the system availability at a specified acceptable level. (C) 2011 Elsevier Ltd. All rights reserved.
Snapback repellers and homoclinic orbits for multi-dimensional maps
(2012-02-01)
Liao, Kang-Ling
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Shih, Chih-Wen
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應用數學系
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Department of Applied Mathematics
Marotto extended Li-Yorke's theorem on chaos from one-dimension to multi-dimension through introducing the notion of snapback repeller in 1978. Due to a technical flaw, he redefined snapback repeller in 2005 to validate this theorem. This presentation provides two methodologies to facilitate the application of Marotto's theorem. The first one is to estimate the radius of repelling neighborhood for a repelling fixed point. This estimation is of essential and practical significance as combined with numerical computations of snapback points. Secondly, we propose a sequential graphic-iteration scheme to construct homoclinic orbit for a repeller. This construction allows us to track the homoclinic orbit. Applications of the present methodologies with numerical computation to a chaotic neural network and a predator-prey model are demonstrated. (C) 2011 Elsevier Inc. All rights reserved.
Influence of polymer dielectric surface energy on thin-film transistor performance of solution-processed triethylsilylethynyl anthradithiophene (TES-ADT)
(2012-02-01)
Chen, Liang-Hsiang
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Lin, Pang
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Kim, Choongik
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Chen, Ming-Chou
;
Huang, Peng-Yi
This study investigates the correlation between surface energy of polymer dielectrics and the film morphology, microstructure, and thin-film transistor performance of solution-processed 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) films. The low surface energy polyimide (PI) dielectric induced large grains with strong X-ray reflections for spin-cast TES-ADT films in comparison to high surface energy poly(4-vinyl phenol) (PVP) dielectric. Furthermore, thin-film transistors based on spin-cast TES-ADT films on PI dielectric exhibited enhanced electrical performance, small hysteresis, and high stability under bias stress with carrier mobility as high as 0.43 cm(2)/Vs and a current on/off ratio of 10(7). (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Performance-Driven Architectural Synthesis for Distributed Register-File Microarchitecture with Inter-Island Delay
(2012-02-01)
Huang, Juinn-Dar
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Chen, Chia-I
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Hsu, Wan-Ling
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Lin, Yen-Ting
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Jou, Jing-Yang
In deep-submicron era, wire delay is becoming a bottleneck while pursuing higher system clock speed. Several distributed register (DR) architectures are proposed to cope with this problem by keeping most wires local. In this article, we propose the distributed register-file microarchitecture with inter-island delay (DRFM-IID). Though DRFM-IID is also one of the DR-based architectures, it is considered more practical than the previously proposed DRFM, in terms of delay model. With such delay consideration, the synthesis task is inherently more complicated than the one without inter-island delay concern since uncertain interconnect latency is very likely to seriously impact on the whole system performance. Therefore we also develop a performance-driven architectural synthesis framework targeting DRFM-IID. Several factors for evaluating the quality of results, such as number of inter-island transfers, timing-criticality of transfer, and resource utilization balancing, are adopted as the guidance while performing architectural synthesis for better optimization outcomes. The experimental results show that the latency and the number of inter-cluster transfers can be reduced by 26.9% and 37.5% on average; and the latter is commonly regarded as an indicator for power consumption of on-chip communication.