Browsing by Issue Date, starting with "2014-08-29"

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Zebrafish WNK Lysine Deficient Protein Kinase 1 (wnk1) Affects Angiogenesis Associated with VEGF Signaling
(2014-08-29)
Lai, Ju-Geng
;
Tsai, Su-Mei
;
Tu, Hsiao-Chen
;
Chen, Wen-Chuan
;
Kou, Fong-Ji
The WNK1 (WNK lysine deficient protein kinase 1) protein is a serine/threonine protein kinase with emerging roles in cancer. WNK1 causes hypertension and hyperkalemia when overexpressed and cardiovascular defects when ablated in mice. In this study, the role of Wnk1 in angiogenesis was explored using the zebrafish model. There are two zebrafish wnk1 isoforms, wnk1a and wnk1b, and both contain all the functional domains found in the human WNK1 protein. Both isoforms are expressed in the embryo at the initiation of angiogenesis and in the posterior cardinal vein (PCV), similar to fms-related tyrosine kinase 4 (flt4). Using morpholino antisense oligonucleotides against wnk1a and wnk1b, we observed that wnk1 morphants have defects in angiogenesis in the head and trunk, similar to flk1/vegfr2 morphants. Furthermore, both wnk1a and wnk1b mRNA can partially rescue the defects in vascular formation caused by flk1/vegfr2 knockdown. Mutation of the kinase domain or the Akt/PI3K phosphorylation site within wnk1 destroys this rescue capability. The rescue experiments provide evidence that wnk1 is a downstream target for Vegfr2 (vascular endothelial growth factor receptor-2) and Akt/PI3K signaling and thereby affects angiogenesis in zebrafish embryos. Furthermore, we found that knockdown of vascular endothelial growth factor receptor-2 (flk1/vegfr2) or vascular endothelial growth factor receptor-3 (flt4/vegfr3) results in a decrease in wnk1a expression, as assessed by in situ hybridization and q-RT-PCR analysis. Thus, the Vegf/Vegfr signaling pathway controls angiogenesis in zebrafish via Akt kinase-mediated phosphorylation and activation of Wnk1 as well as transcriptional regulation of wnk1 expression.
Zebrafish WNK Lysine Deficient Protein Kinase 1 (wnk1) Affects Angiogenesis Associated with VEGF Signaling
(2014-08-29)
Lai, Ju-Geng
;
Tsai, Su-Mei
;
Tu, Hsiao-Chen
;
Chen, Wen-Chuan
;
Kou, Fong-Ji
The WNK1 (WNK lysine deficient protein kinase 1) protein is a serine/threonine protein kinase with emerging roles in cancer. WNK1 causes hypertension and hyperkalemia when overexpressed and cardiovascular defects when ablated in mice. In this study, the role of Wnk1 in angiogenesis was explored using the zebrafish model. There are two zebrafish wnk1 isoforms, wnk1a and wnk1b, and both contain all the functional domains found in the human WNK1 protein. Both isoforms are expressed in the embryo at the initiation of angiogenesis and in the posterior cardinal vein (PCV), similar to fms-related tyrosine kinase 4 (flt4). Using morpholino antisense oligonucleotides against wnk1a and wnk1b, we observed that wnk1 morphants have defects in angiogenesis in the head and trunk, similar to flk1/vegfr2 morphants. Furthermore, both wnk1a and wnk1b mRNA can partially rescue the defects in vascular formation caused by flk1/vegfr2 knockdown. Mutation of the kinase domain or the Akt/PI3K phosphorylation site within wnk1 destroys this rescue capability. The rescue experiments provide evidence that wnk1 is a downstream target for Vegfr2 (vascular endothelial growth factor receptor-2) and Akt/PI3K signaling and thereby affects angiogenesis in zebrafish embryos. Furthermore, we found that knockdown of vascular endothelial growth factor receptor-2 (flk1/vegfr2) or vascular endothelial growth factor receptor-3 (flt4/vegfr3) results in a decrease in wnk1a expression, as assessed by in situ hybridization and q-RT-PCR analysis. Thus, the Vegf/Vegfr signaling pathway controls angiogenesis in zebrafish via Akt kinase-mediated phosphorylation and activation of Wnk1 as well as transcriptional regulation of wnk1 expression.
Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method
(2014-08-29)
Tsai, Wan-Lin
;
Wang, Kuang-Yu
;
Chang, Yao-Jen
;
Li, Yu-Ren
;
Yang, Po-Yu
For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400 degrees C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Omega/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.
Multiplex stimulated Raman imaging with white probe-light from a photonic-crystal fibre and with multi-wavelength balanced detection
(2014-08-30)
Seto, K.
;
Okuda, Y.
;
Tokunaga, E.
;
Kobayashi, T.
;
電子物理學系
A straightforward method for spectral stimulated Raman scattering (SRS) microscopy is to measure the scanned gain/loss spectrum of a white probe light from a photonic crystal fibre (PCF). However, the intensity of the white light noise is a serious problem for SRS microscopy. In this study, we have demonstrated simultaneous two-wavelength SRS microscopy with PCF through balanced detection suitable for spectroscopy with a modification of an auto-balance scheme. The developed auto-balance detection system suppresses the degradation of noise cancellation performance caused by a sample, and is suitable for spectral SRS imaging with simple and robust optics.
Studies on the photocatalysis of core-shelled SiO2-Ag nanospheres by controlled surface plasmon resonance under visible light
(2014-08-30)
Pan, Ko-Ying
;
Liang, Yi-Fan
;
Pu, Ying-Chih
;
Hsu, Yung-Jung
;
Yeh, Jien-Wei
Abundant core-shelled silica-silver nanospheres with uniform diameter and morphology were successfully synthesized by Stober and seed-mediated method, in sequence. By the different additions of glucose, the silver nanoparticles were deposited on silica spheres by redox reaction, which well controlled in the range from 10 to 50 nm. The surface plasmon resonance absorption band shifted toward infra-red region and became broader gradually during the dimensions of silver nanoparticles were increased in the growth range. The amazing data imply that using core-shelled silica-silver nanospheres efficiently enhances the degradation of the organic pollutants under solar energy, which means the core-shelled silica-silver nanospheres is not only a cost-effective route but an energy-saving way to our planet. (C) 2014 Elsevier B.V. All rights reserved.
Structural imperfections and attendant localized/itinerant ferromagnetism in ZnO nanoparticles
(2014-08-30)
Yang, Chao-Yao
;
Lu, Yi-Hsuan
;
Lin, Wei-Hao
;
Lee, Min-Han
;
Hsu, Yung-Jung
Using synchrotron-based x-ray magnetic spectroscopy, we report a study focusing on the local symmetry of Cu-dopant and resultant structural imperfections in mediating Cu-doped ZnO nanoparticles\' ferromagnetism (FM). Prepared by an antisolvent method, Cu appeared to preferably populate on the basal plane of ZnO with a local symmetry of [CuO4]. This unique symmetry was antiferromagnetic in nature, while electronically and structurally coupled to surrounded oxygen vacancies (V-o) that yielded a localized FM, because of a strong dependency on the number/location of the [CuO4] symmetry. Surprisingly, the FM of undoped but oxygen-deficient ZnO appeared to be more itinerant and long-range, where V-o percolated the FM effectively and isotropically through oxygen\'s delocalized orbital. By adopting the approach of structural imperfection, this study clearly identifies V-o\'s (defect\'s) true characters in mediating the FM of magnetic semiconductors which has been thought of as a long-standing debate, and thus provides a different thinking about the traditional extrinsic ferromagnetic-tuning in the semiconductors. It even illuminates recent research concerning the intrinsic FM of low-dimensional systems that contain defects but non-magnetic elements.
Multiplex stimulated Raman imaging with white probe-light from a photonic-crystal fibre and with multi-wavelength balanced detection
(2014-08-30)
Seto, K.
;
Okuda, Y.
;
Tokunaga, E.
;
Kobayashi, T.
;
電子物理學系
A straightforward method for spectral stimulated Raman scattering (SRS) microscopy is to measure the scanned gain/loss spectrum of a white probe light from a photonic crystal fibre (PCF). However, the intensity of the white light noise is a serious problem for SRS microscopy. In this study, we have demonstrated simultaneous two-wavelength SRS microscopy with PCF through balanced detection suitable for spectroscopy with a modification of an auto-balance scheme. The developed auto-balance detection system suppresses the degradation of noise cancellation performance caused by a sample, and is suitable for spectral SRS imaging with simple and robust optics.
合和小農村伯公守護百年
(2014-08-30)
張婷芳
;
Department of Communication and Technology
;
傳播與科技學系
美濃小鎮，在那一天煙雨朦朧的梳洗下顯得格外靜謐。合和里濕漉漉的街道兩側，是黃中帶些翠綠的農田，整里範圍更如同在地主要產業，呈一稻桿狀。
Studies on the photocatalysis of core-shelled SiO2-Ag nanospheres by controlled surface plasmon resonance under visible light
(2014-08-30)
Pan, Ko-Ying
;
Liang, Yi-Fan
;
Pu, Ying-Chih
;
Hsu, Yung-Jung
;
Yeh, Jien-Wei
Abundant core-shelled silica-silver nanospheres with uniform diameter and morphology were successfully synthesized by Stober and seed-mediated method, in sequence. By the different additions of glucose, the silver nanoparticles were deposited on silica spheres by redox reaction, which well controlled in the range from 10 to 50 nm. The surface plasmon resonance absorption band shifted toward infra-red region and became broader gradually during the dimensions of silver nanoparticles were increased in the growth range. The amazing data imply that using core-shelled silica-silver nanospheres efficiently enhances the degradation of the organic pollutants under solar energy, which means the core-shelled silica-silver nanospheres is not only a cost-effective route but an energy-saving way to our planet. (C) 2014 Elsevier B.V. All rights reserved.
Embedded Driver-Assistance System Using Multiple Sensors for Safe Overtaking Maneuver
(2014-09-01)
Chiang, Hsin-Han
;
Chen, Yen-Lin
;
Wu, Bing-Fei
;
Lee, Tsu-Tian
;
交大名義發表
Advanced driver-assistance systems have recently become one of the most active topics related to intelligent vehicles. Such assistance facilitates vehicular operation by allowing drivers increased control and an enhanced driving experience, and it even comes in the form of automated assistance for autonomous vehicle operation. This paper presents a driver-assistance system that uses a low-cost embedded digital signal processor, with the overall system installed in a commercial vehicle. Based on driving information supplied by multiple sensors, such as a real-time vision system, a vehicle-to-vehicle communication system, and in-vehicle sensors, the proposed system can facilitate decision making and the performing of driving tasks while executing overtaking maneuvers. This paper developed a data fusion stage based on a collision warning algorithm in which the overtaken vehicle and other vehicles in the neighboring lane are accounted for to avoid collisions. The system employs fuzzy control in the steering and speed automation to emulate the driving tasks performed by humans. The applicability of the proposed system was examined in a real-road environment, and a set of experimental results demonstrate the feasibility of using the involved coordination strategies while conducting various driving maneuvers.
Optimal sample sizes for the design of reliability studies: Power consideration
(2014-09-01)
Shieh, Gwowen
;
管理科學系
;
Department of Management Science
Intraclass correlation coefficients are used extensively to measure the reliability or degree of resemblance among group members in multilevel research. This study concerns the problem of the necessary sample size to ensure adequate statistical power for hypothesis tests concerning the intraclass correlation coefficient in the one-way random-effects model. In view of the incomplete and problematic numerical results in the literature, the approximate sample size formula constructed from Fisher\'s transformation is reevaluated and compared with an exact approach across a wide range of model configurations. These comprehensive examinations showed that the Fisher transformation method is appropriate only under limited circumstances, and therefore it is not recommended as a general method in practice. For advance design planning of reliability studies, the exact sample size procedures are fully described and illustrated for various allocation and cost schemes. Corresponding computer programs are also developed to implement the suggested algorithms.
Purification, crystallization and preliminary X-ray crystallographic analysis of glycosyltransferase-1 from Bacillus cereus
(2014-09-01)
Hsieh, Yin-Cheng
;
Chiu, Hsi-Ho
;
Huang, Yen-Chieh
;
Fun, Hoong-Kun
;
Lu, Chia-Yu
Glycosyltransferases (GTs), which are distributed widely in various organisms, including bacteria, fungi, plants and animals, play a role in synthesizing biological compounds. Glycosyltransferase-1 from Bacillus cereus (BcGT-1), which is capable of transferring glucose to small molecules such as kaempferol and quercetin, has been identified as a member of the family 1 glycosyltransferases which utilize uridine diphosphate glucose (UDP-glucose) as the sugar donor. BcGT-1 (molecular mass 45.5 kDa) has been overexpressed, purified and crystallized using the hanging-drop vapour-diffusion method. According to X-ray diffraction of BcGT-1 crystals to 2.10 angstrom resolution, the crystal belonged to space group P1, with unit-cell parameters a = 54.56, b = 84.81, c = 100.12 A, alpha = 78.36, beta = 84.66, gamma = 84.84 degrees. Preliminary analysis indicates the presence of four BcGT-1 molecules in the asymmetric unit with a solvent content of 50.27%.
Effect of the Circle-Grid Electrodes on Concentrated GaAs Solar Cell Efficiency
(2014-09-01)
Chung, Chen-Chen
;
Binh Tinh Tran
;
Han, Ming-Hung
;
Lin, Kung-Liang
;
Yu, Hung-Wei
In this study, we investigate the effect of the shading factor of the front grid pattern on concentrated solar cell efficiency, taking the trade-off between the series resistance of the electrodes and the amount of incident light into consideration. We examine the thermal effect with regard to five different circle-grid electrode patterns of the front contact. The front contacts with different grid patterns affect the characteristics of light-concentrated-type GaAs single-junction solar cells. The device parameters analyzed include the open-circuit voltage (V-oc), short-circuit current (I-sc), fill factor (FF) and conversion efficiency (eta). The results of our study show that for a concentration ratio greater than 60x with AM1.5G, the device with a shading factor of 7.1% has the best cell efficiency of 27.05%, due to the smaller current crowding at the center spot. The results indicate that the conversion efficiency of solar cells can be improved by establishing a compromise between the shading effect and the series resistance effect.
Bandwidth and Latency Aware Contribution Estimation in P2P Streaming System
(2014-09-01)
Ho, Cheng-Yun
;
Huang, Ming-Hsiang
;
Ho, Cheng-Yuan
;
Tseng, Chien-Chao
;
交大名義發表
In this article, a bandwidth and latency aware contribution estimation (BLACE) mechanism is proposed to enhance the efficiency of content distribution in a mesh peer-to-peer (P2P) streaming system. This is because the mesh P2P streaming system outperforms others in many aspects, but most content distribution mechanisms use only one of upload bandwidth and link latency as a factor, several contribution-aware schemes (CASs) just punish selfish peers, and some CASs only rearrange the content receiving order. Hence, the BLACE proposes a prevention way considering every peer\'s upload bandwidth, link latency, and the maximum playing delay of a stream at the same time to prioritize the content distribution. Moreover, BLACE is implemented on Coolstreaming with NS2 and experimental results show that BLACE could at the most shorten the receiving time about 15.44%, 13.94%, and 8.26%, and improve the whole performance about 7.05%, 2.81%, and 2.69% at the most, when it compares with the Coolstreaming, the Coolstreaming with bandwidth preference, and the Coolstreaming with latency preference, respectively.
Norm-Constrained Capon Beamforming Using Multirank Signal Models With Kalman Filter Implementation
(2014-09-01)
Hu, Jwu-Sheng
;
Lee, Ming-Tang
;
交大名義發表
;
電機工程學系
;
National Chiao Tung University
The performance of the Capon beamforming is known to degrade dramatically in the presence of model mismatches, especially when the desired signal is present in the training data. To improve the robustness, the diagonal loading technique was introduced. However, the major drawback is the selection of the diagonal loading level, which is related to the unknown signal powers. Another way to alleviate performance degradation is to use a more accurate signal model of the array response. In this paper, a norm-constrained Capon beamforming using multirank signal models is proposed. Based on the pseudo-observation method, the quadratic constraints can be easily constructed. The problem is solved by a nonlinear Kalman filter which can be implemented on-line. The simulation results show that the design of the norm-constraint value is less sensitive to the signal powers, small angle mismatches, and number of sensors with a standard linear array. Further, it is shown that the use of a multirank signal model and Kalman filter technique result in less self-cancellation and performance degradation than that of the rank-1 signal model and the estimation of sample matrix.
編按
(國立陽明交通大學出版社, 2014-09-01)
李卓穎
Sample size requirements for the design of reliability studies: precision consideration
(2014-09-01)
Shieh, Gwowen
;
管理科學系
;
Department of Management Science
In multilevel modeling, the intraclass correlation coefficient based on the one-way random-effects model is routinely employed to measure the reliability or degree of resemblance among group members. To facilitate the advocated practice of reporting confidence intervals in future reliability studies, this article presents exact sample size procedures for precise interval estimation of the intraclass correlation coefficient under various allocation and cost structures. Although the suggested approaches do not admit explicit sample size formulas and require special algorithms for carrying out iterative computations, they are more accurate than the closed-form formulas constructed from large-sample approximations with respect to the expected width and assurance probability criteria. This investigation notes the deficiency of existing methods and expands the sample size methodology for the design of reliability studies that have not previously been discussed in the literature.
SENSOR (GROUP FEATURE) SELECTION WITH CONTROLLED REDUNDANCY IN A CONNECTIONIST FRAMEWORK
(2014-09-01)
Chakraborty, Rudrasis
;
Lin, Chin-Teng
;
Pal, Nikhil R.
;
交大名義發表
;
National Chiao Tung University
For many applications, to reduce the processing time and the cost of decision making, we need to reduce the number of sensors, where each sensor produces a set of features. This sensor selection problem is a generalized feature selection problem. Here, we first present a sensor (group-feature) selection scheme based on Multi-Layered Perceptron Networks. This scheme sometimes selects redundant groups of features. So, we propose a selection scheme which can control the level of redundancy between the selected groups. The idea is general and can be used with any learning scheme. We have demonstrated the effectiveness of our scheme on several data sets. In this context, we define different measures of sensor dependency (dependency between groups of features). We have also presented an alternative learning scheme which is more effective than our old scheme. The proposed scheme is also adapted to radial basis function (RBS) network. The advantages of our scheme are threefold. It looks at all the groups together and hence can exploit nonlinear interaction between groups, if any. Our scheme can simultaneously select useful groups as well as learn the underlying system. The level of redundancy among groups can also be controlled.
Spectroscopic Signatures for Interlayer Coupling in MoS2-WSe2 van der Waals Stacking
(2014-09-01)
Chiu, Ming-Hui
;
Li, Ming-Yang
;
Zhang, Wengjing
;
Hsu, Wei-Ting
;
Chang, Wen-Hao
Stacking of MoS2 and WSe2 monolayers is conducted by transferring triangular MoS2 monolayers on top of WSe2 monolayers, all grown by chemical vapor deposition (CVD). Raman spectroscopy and photoluminescence (PL) studies reveal that these mechanically stacked monolayers are not closely coupled, but after a thermal treatment at 300 degrees C, it is possible to produce van der Waals solids consisting of two interacting transition metal dichalcogenide (TMD) monolayers. The layer-number sensitive Raman out-of-plane mode A(1g)(2) for WSe2 (309 cm(-1)) is found sensitive to the coupling between two TMD monolayers. The presence of interlayer excitonic emissions and the changes in other intrinsic Raman modes such as E \'\' for MoS2 at 286 cm(-1) and A(1g)(2) for MoS2 at around 463 cm(-1) confirm the enhancement of the interlayer coupling.
不需對話的族群分類－寮國北部的「人民」與「國家」
(國立陽明交通大學出版社, 2014-09-01)
謝世忠