Browsing by Issue Date, starting with "2004-07-05"

Now showing 1 - 20 of 69836

Zero-norm states and high-energy symmetries of string theory
(2004-07-05)
Chan, CT
;
Lee, JC
;
電子物理學系
;
Department of Electrophysics
We derive stringy Ward identities from the decoupling of two types of zero-norm states in the old covariant first quantized (OCFQ) spectrum of open bosonic string. These Ward identities are valid to all energy alpha(1) and all loop orders chi in string perturbation theory. The high-energy limit alpha(1) --> infinity of these stringy Ward identities can then be used to fix the proportionality constants between scattering amplitudes of different string states algebraically without referring to Gross and Mende's saddle point calculation of high-energy string-loop amplitudes. As examples, all Ward identities for the mass level M-2 = 4, 6 are derived, their high-energy limits are calculated and the proportionality constants between scattering amplitudes of different string states are determined. In addition to those identified before, we discover some new nonzero components of high-energy amplitudes not found previously by Gross and Manes. These components are essential to preserve massive gauge invariances or decouple massive zero-norm states of string theory. A set of massive scattering amplitudes and their high-energy limits are calculated explicitly for each mass level M-2 = 4, 6 to justify our results. (C) 2004 Elsevier B.V. All rights reserved.
Embeddings of maximum packings in triple systems
(2004-07-06)
Su, RW
;
Fu, HL
;
Shen, H
;
應用數學系
;
Department of Applied Mathematics
Let MPT(v,lambda) denote a maximum packing of triples of order v with index lambda and TS(u, lambda) denote a triple system of order u with index lambda. For lambda > 1 and v greater than or equal to 6, it is proved in this paper that the necessary and sufficient conditions for the embedding of an MPT(v, lambda) in a TS(u, lambda) are lambda(u - 1) equivalent to 0 (mod 2), lambdau(u - 1) equivalent to 0 (mod 6) and u greater than or equal to 2v + 1. (C) 2003 Published by Elsevier B.V.
Decomposing K-n UP into triangles
(2004-07-06)
Fu, CM
;
Fu, HL
;
Rodger, CA
;
應用數學系
;
Department of Applied Mathematics
In this paper, we extend the work on minimum coverings of K-n with triangles. We prove that when P is any forest on n vertices the multigraph G = K-n boolean OR P can be decomposed into triangles if and only if three trivial necessary conditions are satisfied: (i) each vertex in G has even degree, (ii) each vertex in P has odd degree, and (iii) the number of edges in G is a multiple of 3. This result is of particular interest because the corresponding packing problem where the leave is any forest is yet to be solved. We also consider some other families of packings, and provide a variation on a proof by Colbourn and Rosa which settled the packing problem when P is any 2-regular graph on at most n vertices. (C) 2004 Elsevier B.V. All rights reserved.
A self-consistent investigation of the semimetal-semiconductor transition in InAs/GaSb quantum wells under external electric fields
(2004-07-07)
Lapushkin, I
;
Zakharova, A
;
Yen, ST
;
Chao, KA
;
電子工程學系及電子研究所
We investigate the phase transitions in InAs/GaSb quantum wells sandwiched between two wide-gap AlSb barrier layers under an external electric field perpendicular to interfaces. The Schrodinger and the Poisson equations are solved self-consistently to derive the subband dispersions, the potential profile, the electron charge distribution in the InAs layer, and the hole charge distribution in the GaSb layer. The Burt-Foreman envelope function theory and the scattering matrix method are used to solve the Schrodinger equation in the framework of the eight-band k (.) p model, including the spin-splitting of subbands in our calculation. We have found that in a thick InAs/GaSb quantum well, which has been investigated experimentally by Cooper et al (1998 Phys. Rev. B 57 11915), under low external electric fields, two electron levels stay below the highest hole level at zero in-plane wavevector k(parallel to) = 0. Then, the anticrossings of electron and hole levels produce several minigaps in the inplane dispersions, inside which the states of other subbands exist. As a result, the system is in a sernimetal phase. With increasing external electric field, the semimetal phase changes to semiconductor phase with only one hybridization gap. When all electron levels become higher than the hole levels at higher electric fields, the system has a semiconducting gap.
Observation of a reactive resonance in the integral cross section of a six-atom reaction: F+CHD3
(2004-07-08)
Zhou, JG
;
Lin, JJ
;
Liu, KP
;
應用化學系
;
Department of Applied Chemistry
The title reaction was investigated under crossed-beam conditions at collisional energies ranging from about 0.4 to 7.5 kcal/mol. Product velocity distributions were measured by a time-sliced, velocity-map imaging technique to explicitly account for the density-to-flux transformation factors. Both the state-resolved, pair-correlated excitation functions and vibrational branching ratios are presented for the two isotopic product channels. An intriguing resonance tunneling mechanism occurring near the reaction threshold for the HF+CD3 product channel is surmized, which echoes the reactive resonances found previously for the F+HD-->HF+D reaction and more recently for the F+CH4 reaction. (C) 2004 American Institute of Physics.
Method to control the magnetic alloy-encapsulated carbon-base nanostructures
(2004-07-08)
Cheng-Tzu, Kuo
;
Chao-Hsun, Lin
;
An-Ya, Lo
;
Po-Yuan, Lo
The present invention provides a method to control the magnetic alloy-encapsulated carbon-base nanostructures apply an appropriate amount of magnetic field during magnetic alloy-encapsulated nanostructure deposition and post treatment for improved magnetic anisotropy by electron cyclotron resonance chemical vapor deposition (ECR-CVD), the catalyst and additive on surface of substrate use DC bias and heating treatment and then etching the substrate during plasma pretreatment. The present invention is to provide control of the size and shape of the nanostructures, capability to be effectively manipulated the magnetic anisotropy and coercive force of the encapsulated magnetic nanoparticles, capability to store the magnetic signals with nano-resolution.
Quasisuperlattice storage: A concept of multilevel charge storage
(2004-07-12)
Chang, TC
;
Yan, ST
;
Liu, PT
;
Chen, CW
;
Wu, HH
A concept of the quasisuperlattice storage has been demonstrated in this study. Under suitably operated voltage, two apparent states of charge storage can be distinguished. The memory effects are due to the multilevel storage in the quasisuperlattice. Also, the a-Si quantum wells provide a feasible design for the 2 bit per cell nonvolatile memory devices. The operation of the 2 bit per cell needs to be performed by Fowler-Nordheim tunneling instead of conventional channel hot electron injection. Additionally, the dual read operation of the source and drain sides for conventional SONOS 2 bit/cell device is not necessary, which simplifies the circuit design engineering. (C) 2004 American Institute of Physics.
Detection of serum uric acid using the optical polymeric enzyme biochip system
(2004-07-15)
Huang, SH
;
Shih, YC
;
Wu, CY
;
Yuan, CJ
;
Yang, YS
An optical polymeric biochip system based on the complementary metal oxide semiconductor (CMOS) photo array sensor and polymeric enzyme biochip for rapidly quantitating uric acid in a one-step procedure was developed. The CMOS sensor was designed with N+/P-well structure and manufactured using a standard 0.5 mum CMOS process. The polymeric enzyme biochip was immobilized with uricase-peroxidase and used to fill the reacting medium with the sample. This study encompasses the cloning of the Bacillus subtilis uricase gene and expression in Escherichia coli, as well as the purification of uricase and measurement of its activity. The cloned uricase gene included an open reading frame of 1491 nucleotides that encodes a protein of approximately 55 kDa. The expression of the putative MBP-fusion protein involved approximately 98 kDa of the protein. The CMOS sensor response was stronger at a higher temperature range of 20-40degreesC, with optimal pH at 8.5. The calibration curve of purified uric acid was linear in the concentration range from 2.5 to 12.5 mg/dL. The results obtained for serum uric acid correlated quite closely with those obtained using the Beckman Synchron method. (C) 2004 Elsevier B.V All rights reserved.
Method for manufacturing a combined solid immersion lens (SIL) and submicron aperture, and device thereof
(2004-07-15)
Wensyang, Hsu
;
Hsueh, Chou
;
Chung, Tien
The invention relates to an integrated method for manufacturing a combined solid immersion lens (SIL) and submicron aperture, and device thereof, comprising depositing a sacrificial layer on a substrate, coating a photoresist on the sacrificial layer and using photo-lithography to form an aperture on the photoresist, applying reflow and etching process to remove the sacrificial layer below the aperture, depositing a conductive material on the photoresist and performing electroplating to reduce the aperture size, then coating another photoresist and using photo-lithography to form a cylindrical phtoresist above the aperture, applying a high temperature thermal reflow to form a microlens, and finally removing the substrate to obtain an optical read/write apparatus with a combined solid immersion lens (SIL) and submicron aperture.
Variable optical attenuator using a thermal actuator array with dual shutters
(2004-07-15)
Chiou, JC
;
Lin, WT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A compact variable optical attenuator (VOA) driving by thermal actuating principle with dual shutters for single mode fibers is developed. The fabricated thermal actuator array is capable of achieving larger displacement with low applied voltage than traditional thermal actuator array. The designed dual shutters can be driven independently or simultaneously, which increase the accurate tuning range and decrease working voltage for variable optical attenuator. The device is fabricated using MEMS-SOI fabrication technology, which greatly simplifies the traditional surface micromachining technology and increases its corresponding reliability. The newly designed thermal actuator array is capable of traveling 20 Pm distance with less than 5 V applied voltage for VOA application. The insertion loss of the fabricated VOA is below 1.5 dB. The initial return loss and working return loss is about 50 and 40 dB, respectively. Experimental results indicated that the response time is below 4 ms and maximum attenuation range is about 40 and 45 dB at 1550 and 1310 nm, respectively. The working voltage and temperature of the designed VOA is under 5 V and 550 K, respectively. (C) 2004 Elsevier B.V. All rights reserved.
Low-temperature solution approach toward highly aligned ZnO nanotip arrays
(2004-07-15)
Hung, CH
;
Whang, WT
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Highly aligned and free-standing ZnO nanotip arrays grown on the ZnO films by soft chemical method are proposed. X-ray diffraction analysis shows that the ZnO nanotips are hexagonal wurtzite structure, and the c-axes of nanotips are perfectly along the substrate surface normal. HRTEM demonstrates the ZnO nanotip to be a single crystal. Room temperature photoluminescence of the ZnO nanotips has a strong UV emission band at 378 nm. The field emission of ZnO nanotip arrays shows a turn-on field of about 10.8 V/mum at a current density of 0.1 muA/cm and emission current density up to about 1 mA/cm(2) at a bias field of 19.5 V/mum. The mild technique for fabricating ZnO nanotip arrays is believed to open novel possibilities for nanoscale optoelectronic device applications. (C) 2004 Elsevier B.V. All rights reserved.
Direct evidence of open ray orbits in a square two-dimensional resonator of dye-doped polymers
(2004-07-15)
Chern, GD
;
Poon, AW
;
Chang, RK
;
Ben-Messaoud, T
;
Alloschery, O
Lasing has been observed in optically pumped 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyrl)-4H-pyran-doped poly(methyl methacrylate) square-shaped micropillars that allow four-bounce closed and open ray orbits with internal incident angle theta(inc) > theta(c) (the critical angle for total internal reflection) and with the associated surface waves that emit at the four corners. We also detect strongly TE-polarized and spatially varying omission from the square sidewalls that is due to leaky open ray orbits with theta(inc) near but less than theta(c) for two of the four bounces. By selectively pumping the square microcavity with a stripe-shaped beam, we excite different four-bounce ray orbits. (C) 2004 Optical Society of America.
Compromise solution by MCDM methods: A comparative analysis of VIKOR and TOPSIS
(2004-07-16)
Opricovic, S
;
Tzeng, GH
;
科技管理研究所
;
Institute of Management of Technology
The multiple criteria decision making (MCDM) methods VIKOR and TOPSIS are based on an aggregating function representing "closeness to the ideal", which originated in the compromise programming method. In VIKOR linear normalization and in TOPSIS vector normalization is used to eliminate the units of criterion functions. The VIKOR method of compromise ranking determines a compromise solution, providing a maximum "group utility" for the "majority" and a minimum of an individual regret for the "opponent". The TOPSIS method determines a solution with the shortest distance to the ideal solution and the greatest distance from the negative-ideal solution, but it does not consider the relative importance of these distances. A comparative analysis of these two methods is illustrated with a numerical example, showing their similarity and some differences. (C) 2003 Elsevier B.V. All rights reserved.
新舊警衛隊長交接典禮
(國立陽明大學, 2004-07-16)
陽明電子報編輯小組
下午兩點半，會議室中擠滿了人，總務處各組室的同仁幾乎全數到場參與交接典禮，由宋總務長晏仁主持監交儀式。警衛隊隊長由各隊員輪流任職一年的制度，自宋總務長上任伊始；新任盧天心隊長即將展開的是第四屆的任期
腦科學中心 - 93年度計畫構想書
(國立陽明大學, 2004-07-16)
陽明電子報編輯小組
腦科學中心 - 93年度計畫構想書
走過布拉格──歐洲最美麗的城市
(國立陽明大學, 2004-07-16)
醫工所．夏正忠
;
陽明電子報編輯小組
有人說，春天要去布拉格；有人說，布拉格任何景點都像是一幅畫，任何角度都適合攝影；夏正忠說，沒有走過布拉格，無法領略歐洲之美
徵稿公告
(國立陽明大學, 2004-07-16)
陽明電子報編輯小組
一、龍華科技大學「二００四物流產業電子化學術與實務研討會」徵稿截稿日期：九十三年七月二十日相關網址：http://elogistics.lhu.edu.tw 二、明道管理學院「二００四年災後重建、學校教學及學生輔導國際學術研討會」徵稿截稿日期：九十三年七月三十日相關網址：http://www.mdu.edu.tw/~ita/index00.htm 三、國立台北師範學院「國立台北師範學院學報」徵稿截稿日期：九十三年九月三十日相關網址：http://academic.ntptc.edu.tw/public/home.htm
請踴躍參加「第七屆台北國際愛滋病研討會」
(國立陽明大學, 2004-07-16)
陽明電子報編輯小組
第七屆台北國際愛滋病研討會地點：台北圓山大飯店台北市104中山北路4段1號時間：7月17日至7月20日，現場有中英文同步翻譯設施報名方式：可貼報名表傳真至02-29245511大會祕書處群策國際會議顧問股份有限公司；或至大會網站上報名
神經再生專論Special Lecture on Neural Regeneration
(國立陽明大學, 2004-07-16)
陽明電子報編輯小組
授課教師：鄭宏志副教授 (台北榮總神經醫學中心神經修復科主任) 課程對象：陽明大學部學生及研究所學生課程時間：93年7月5日至93年8月9日每週一、三 9:10-11:00 課程學分：1學分(於93年度第1學期陽明大學藥理學研究所課程進行加選) 授課地點：7/5 於陽明生命科學系會議室(實驗大樓四樓) 7/7-8/9 於陽明藥理所會議室(研究大樓四樓458室) 承辦人：藥理所許馨文分機7141
校園步道
(國立陽明大學, 2004-07-16)
崇平
;
陽明電子報編輯小組
夏天的腳步近了.. 艷陽高照的午後.. 校園的步道，綠葉成蔭.. 涼風徐徐...帶來枕木的氣息.. 按下快門，抓住春天的尾巴.....