398 results on '"T. C. Yang"'
Search Results
152. Grids-Based Data Parallel Computing for Learning Optimization in a Networked Learning Control Systems
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Minrui Fei, Wei Yu, Lijun Xu, and T. C. Yang
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Scheme (programming language) ,Active learning (machine learning) ,Computer science ,Distributed computing ,Quality of service ,Parallel computing ,computer.software_genre ,Task (project management) ,Utility computing ,Grid computing ,Control system ,computer ,Networked learning ,computer.programming_language - Abstract
This paper investigates a fast parallel computing scheme for the leaning control of a class of two-layered Networked Learning Control Systems (NLCSs). This class of systems is subject to imperfect Quality of Service (QoS) in signal transmission, and requires a real-time fast learning. A parallel computational model for this task is established in the paper. Based on some of grid computing technologies and optimal scheduling, an effective scheme is developed to make full use of distributed computing resources, and thus to achieve a fast multi-objective optimization for the learning task under study. Experiments of the scheme show that it indeed provides a required fast on-line learning for NLCSs. more...
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- 2010
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153. System capacity of CDMA, TDMA and FDMA in cluster type underwater acoustic networks
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T. C. Yang and Zaihan Jiang
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Engineering ,Channel allocation schemes ,business.industry ,Code division multiple access ,Bandwidth (signal processing) ,Time division multiple access ,Electronic engineering ,Radio frequency ,Underwater ,business ,Sonar ,Cluster type - Abstract
It is well acknowledged that CDMA scheme could achieve higher system capacity in cellular type Radio Frequency networks (RFN) than either TDMA or FDMA, since the system capacity of TDMA or FDMA is resource (bandwidth) restricted, while the one of CDMA is interference restricted; and the interference level can be reduced by lowering the user activity ratio and controlling of transmission power. However, this conclusion could not be applied to underwater acoustic networks (UANs) due to the significant differences between propagation environment of RFNs and that of UANs. Using sonar equation and with the Thorp's water absorption formula, this paper analyzes the capacity of CDMA, TDMA and FDMA schemes in a cluster type underwater acoustic network. In the following analysis, all the power symbols, e.g., Pts, Pintracluster, etc., represent time average value instead of instantaneous value. more...
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- 2010
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154. Modeling of the Human Bronchial Tree and Simulation of Internal Airflow: A Review
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Yijuan Di, T. C. Yang, Minrui Fei, and Xin Sun
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Engineering ,business.industry ,Airflow ,respiratory system ,Software package ,computer.software_genre ,respiratory tract diseases ,Modeling and simulation ,Tree (data structure) ,Fresh air ,Data mining ,business ,computer ,Simulation ,Simulation methods - Abstract
Human bronchial tree is breath passage between pulmonary capillary vessel and fresh air and it is a key part of the human respiratory system. Clinical experience shows that abnormal or diseases of the respiratory system often occur at some bifurcated segments of the bronchial tree. Therefore, for better diagnosis and treatment of such diseases, it is necessary to investigate morphology structure of human bronchial tree and its internal airflow dynamics. In this paper, approaches for the modeling of bronchial tree are outlined based on the morphology structure data obtained from the two sources, i.e. anatomical experiments and CT/MRI. In addition, the simulation of airflow in bifurcating airways is summarized from the aspect of simulation methods and CFD. Finally, possible future research is suggested to develop: (1) a universal dynamic model of the airflow in the bronchial tree; and (2) a user-friendly software package for modeling and simulation. more...
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- 2010
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155. Comparative performance of matched‐mode and matched‐field localization in a range‐dependent environment
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Christopher W. Bogart and T. C. Yang
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Signal processing ,Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Sensor array ,Normal mode ,Acoustics ,Speed of sound ,Refraction (sound) ,Range (statistics) ,Underwater ,Underwater acoustics ,Geology - Abstract
Matched‐mode localization has been proposed recently as an alternative to matched‐field processing for underwater source localization. It involves processing in mode space rather than phone space, and requires much less processing time compared to match‐field processing. To date, studies of matched‐mode processing have concentrated on single vertical arrays in range‐independent environments. In this paper, matched‐mode localization of a source in range, depth, and bearing using twin vertical arrays is demonstrated using simulated acoustic data. The environment considered consists of sloping bottoms with a sound speed increasing with depth. Acoustic modeling assumes adiabatic normal modes, neglecting horizontal refraction. Results of source localization are compared for both a range‐independent environment and for matched‐mode processing versus matched‐field processing. It is found that for the cases studied the matched‐mode processing is an order of magnitude faster than the matched‐field processing for range‐depth searches, and the time difference is greater for range‐bearing searches. The matched‐mode ambiguity surface shows equal or slightly improved (lower) sidelobe levels compared with that of matched‐field processing. Results of source localization are compared for arrays of different number of phones, different vertical spacings, and different locations. The arrays that resolve more modes generally have better performance. more...
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- 1992
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156. Load-adaptive control of a single-link flexible manipulator
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P. Kudva, T.-C. Yang, and J.C.S. Yang
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Adaptive control ,business.industry ,Estimation theory ,Computer science ,Payload (computing) ,General Engineering ,System identification ,Robotics ,Control theory ,Robot ,Artificial intelligence ,Transient (oscillation) ,Manipulator ,business - Abstract
An adaptive control scheme for the tip position control of a single-link flexible manipulator handling unknown changing loads and its experimental verification are presented. The scheme essentially comprises a least-squares identification algorithm and a self-tuning pole-placement controller. The controller uses a novel recursive algorithm which constrains the control signal not to respond immediately to any sudden changes in the control gains due to changes in the parameter estimate vector. Another salient feature of the present work is the observation of a 'ringing effect' transient during payload release and its resolution. This was achieved by a resetting of the parameter estimate vector to its no-load value, prior to payload release. A performance comparison of the new adaptive control with a constant-gain pole placement controller as well as a standard self-tuning pole placement controller clearly demonstrates its superior ability in handling unknown changing loads. > more...
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- 1992
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157. The Effect of the Puffed Gas Shell Profile on Plasma Dynamics in a Small Gas-Puff Z-Pinch
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C. M. Luo, M. Han, Cheng Rong Li, and T. C. Yang
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Materials science ,Argon ,020209 energy ,Nozzle ,General Engineering ,Shell (structure) ,Implosion ,chemistry.chemical_element ,02 engineering and technology ,Plasma ,01 natural sciences ,010305 fluids & plasmas ,Physics::Fluid Dynamics ,chemistry ,Physics::Plasma Physics ,Ionization ,Z-pinch ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,0202 electrical engineering, electronic engineering, information engineering ,Plasma diagnostics ,Atomic physics ,Astrophysics::Galaxy Astrophysics - Abstract
An argon annular gas-puff Z-pinch has been experimentally investigated with three different nozzles. The puffed gas shell profiles and the plasma implosion have been measured using a fast ionization gauge and a differential interferometer. These experiments confirm that both the puffed gas density and its distribution may effect the compression process of Z-pinch plasma. more...
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- 1992
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158. Authors
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Walter Seifritz, Walter Väth, Saurin Majumdar, Cheng Rong Li, T. C. Yang, C. M. Luo, M. Han, Giulio Riva, Adolfo Reggiori, Chungpin Liao, Brian Labombard, Barton Lane, Mujid S. Kazimi, N. P. Bhat, Hans U. Borgstedt, D. Gozzi, P. L. Cignini, M. Tomellini, S. Frullani, F. Garibaldi, F. Ghio, M. Jodice, G. M. Urciuoli, Han S. Uhm, W. M. Lee, Wan-Xiang Zhang, F. Cannizzaro, G. Greco, M. Raneli, M. C. Spitale, E. Tomarchio, and Zhong Qun Tian more...
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General Engineering - Published
- 1992
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159. Application of optimal regulator design method through the inverse problem approach to the power system stabilizer design
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N. Munro, A. Brameller, and T.-C. Yang
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Engineering ,business.industry ,Linear regulator ,Linear system ,Energy Engineering and Power Technology ,Linear-quadratic regulator ,Inverse problem ,Linear-quadratic-Gaussian control ,Optimal control ,law.invention ,Electric power system ,Control theory ,law ,Electrical network ,Electrical and Electronic Engineering ,business - Abstract
The theory and application of the optimal control of linear systems to stabilize or improve the system stability is well known (Anderson and Moore, 1971). For an optimal linear regulator design, the arbitrariness involved in the parameters of the cost function always affects the final control law and the closed-loop system poles which decide the system dynamic characteristics. A new approach, ‘The inverse problem approach’ (Yang et al., 1984), has been developed to overcome this difficulty. The system so designed will have preassigned closed-loop poles and the resulting closed-loop system performance can be ensured. In this paper, the inverse problem approach for optimal regulator design is applied to the power system stabilizer (PSS) design for single-machine infinite-bus systems. The results show that, as far as the linearized model is concerned, systems designed by the inverse problem approach have better closed-loop performance than those designed by the classical PSS design approach and a simple way of using a lead-lag compensator plus a PI regulator to realize the optimal state feedback control law is also presented. more...
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- 1991
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160. Abstracts of Posters Presentations
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T. E. Bureau, G. S. Khush, S. R. Wessler, A. S. Reddy, F. Cordesse, M. Delseny, A. Kanno, K. Hattori, A. Hirai, Y. Sano, R. Sano, H. -Y. Hirano, T. Ishii, T. Terachi, N. Mori, K. Tsunewaki, J. P. Gustafson, C. L. Mclntyre, J. E. Dillé, Jinshui Yang, Koulin Ge, Yunzhu Wang, C. C. Tan, Shanbao Chen, Xiaolan Duan, Changsheng Yan, Guandang Xing, Yan Zhang, B. Wang, H. G. Zheng, Q. F. Xu, J. Z. Wang, D. D. Li, S. T. Li, Z. T. Zhang, O. Panaud, G. Magpantay, E. Galinato, D. Mahapatra, L. A. Sitch, S. Yoshimura, A. Yoshimura, N. Iwata, A. Saito, N. Kishimoto, M. Kawase, M. Nakagahra, M. Yano, N. Mitsukawa, K. Tanaka, E. C. Cocking, S. L. Kothari, H. Zhang, P. T. Lynch, P. S. Eyles, E. L. Rech, M. R. Davey, I. H. Slamet, R. P. Finch, K. -I. Mori, T. Kinoshita, A. Tanaka, S. Tano, A. B. Mendoza, Y. Futsuhara, Y. Takeoka, Wang Zixuan, E. Guiderdoni, P. B. Kavi Kishor, G. M. Reddy, N. R. Yadav, D. R. Sharma, J. B. Chowdhury, Jiadao Wu, Zhongxiang Huang, Zuling Liu, Leya Zheng, Jianbo Yan, Yan Chen, K. Fukui, K. Iijima, H. Fukuoka, Y. Kageyama, K. Yamamoto, G. Takeda, I. Imuta, F. Kikuchi, I. Watanabe, M. Yusa, O. Kamijima, H. Kitano, Y. Nagato, S. Kikuchi, H. Satoh, I. Takamure, S. Oba, M. Ichii, Shui Shan Li, H. Hasegawa, A. Matsuzaki, T. Takano, T. Kato, D. A. Vaughan, K. K. Jena, D. S. Multani, A. Ghesquiere, P. Barbier, A. Ishihama, A. A. Flores-Nimedez, K. Dörffling, B. S. Vergara, T. Nagamine, K. Watanabe, T. Nishimura, T. Ogawa, R. E. Tabien, T. Yamamoto, G. A. Busto, R. Ikeda, C. Hamamatsu, Y. -I. Sato, H. Morishima, J. Abadassi, J. C. Glaszmann, J. L. Notteghem, B. Courtois, O. Mohamad, M. Z. Abdullah, O. Othman, K. Hadzim, J. Mahmud, O. Ramli, J. L. Minocha, J. S. Sidhu, R. K. Gupta, H. Sano, S. Youssefian, I. Kamada, M. Itoh, M. T. Mei, Q. F. Zuo, Y. G. Lu, H. Deng, T. C. Yang, T. Tanisaka, H. Yamagata, B. Mishra, J. P. Tilquin, J. P. Chapeaux, J. F. Detry, Yi-Shin Chen, Chia-Yi Aes, Bui Chi Buu, Thai Thi Hanh, Minghong Gu, Aiqing You, Xuebiao Pan, Zu-bai Qi, Ye-Tong Cai, Bao-jian Li, T. Nomura, K. Yonezawa, T. Sato, N. Watanabe, R. B. Austin, C. L. Morgan, Y. Okumoto, Y. Shimamoto, Shih-Cheng Lin, K. Hinata, M. Oka, M. P. Pandey, D. V. Seshu, M. Akbar, Moo Young Eun, Yong Gu Cho, Yong Kwon Kim, Tae Young Chung, Gun-Sik Chung, Sae-Jun Yang, Byeong-Geun Oh, G. L. Shrestha, S. Mallik, A. M. Aguilar, G. Kochert, and I. Nakamura more...
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- 2008
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161. Performance analysis of direct-sequence spread-spectrum underwater acoustic communications with low signal-to-noise-ratio input signals
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T. C. Yang and Wen-Bin Yang
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Spread spectrum ,Signal-to-noise ratio ,Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Acoustics ,Matched filter ,Fading ,Filter (signal processing) ,Direct-sequence spread spectrum ,Signal ,Computer Science::Information Theory ,Mathematics ,Communication channel - Abstract
Direct-sequence spread-spectrum signals collected from the TREX04 experiment are analyzed to determine the bit-error-rate (BER) as a function of the input signal-to-noise ratio (SNR) for a single receiver. A total of 1160 packets of data are generated by adding ambient noise data collected at sea to the signal data (in postprocessing) to create signals with different input-SNR, some as low as -15 dB. Two methods are analyzed in detail, both using a time-updated channel impulse-response estimate as a (matched) filter to mitigate the multipath-induced interferences. The first method requires an independent estimate of the time-varying channel impulse-response function; the second method uses the channel impulse-response estimated from the previous symbol as the matched filter. The first method yields an average BER more...
- Published
- 2008
162. Subbottom profiling using a ship towed line array and geoacoustic inversion
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Kwang Yoo, L. T. Fialkowski, and T. C. Yang
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Beamforming ,Geologic Sediments ,Time Factors ,Acoustics and Ultrasonics ,Acoustics ,Oceans and Seas ,Signal Processing, Computer-Assisted ,Inverse problem ,Models, Theoretical ,Oceanography ,Line array ,Motion ,Sound ,Arts and Humanities (miscellaneous) ,Wide area ,Broadband ,Bathymetry ,Geoacoustic inversion ,Underwater acoustics ,Ships - Abstract
Bottom profiling traditionally uses broadband signals received on a line array at long ranges to estimate the bottom layer structure and thickness. In this paper, a subbottom profiling method is developed and applied to a ship-towed line array using the same ship towed source to estimate the subbottom layer structure and thickness. A ship towed line-array system can be used to estimate bottom properties using geoacoustic inversion and can cover a wide area in a short time. It needs some prior information about the subbottom structure and layer thickness, without which the solution can be ambiguous and even erratic when resolving parameters over a wide area. It is shown that the required subbottom information can be obtained from the time-angle relation by beamforming the same acoustic signal data used for geoacoustic inversion. The time-angle analysis is used to expose the prevalent physics intrinsic to geoacoustic inversion. One finds that the tau-p relation of the bottom and the bottom reflection coefficients, sampled at discrete angles associated with bottom and multiple surface-bottom returns, are often adequate, for many practical applications, to uniquely determine the geoacoustic bottom at low (or =1 kHz) frequencies. more...
- Published
- 2008
163. Effectiveness of mode filtering: A comparison of matched‐field and matched‐mode processing
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T. C. Yang
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Beamforming ,Signal processing ,Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Sensor array ,Acoustics ,Mode (statistics) ,Decomposition method (queueing theory) ,Array gain ,Underwater acoustics ,Eigenvalues and eigenvectors ,Mathematics - Abstract
In a previous paper [T. C. Yang, J. Acoust. Soc. Am. 82, 1736–1745 (1987)] an eigenvector (EIG) mode decomposition method was used as the basis for modal beamforming (matched‐mode processing). In this article, it is pointed out that matched‐field processing is equivalent to a modal beamforming method with a different mode decomposition algorithm (denoted as the MFP‐mode decomposition method). The difference in performance between the two processing schemes can be understood in terms of the effectiveness of mode filtering of the mode decomposition method used. It is found that the difference between the MFP‐ and EIG‐mode decomposition is small if the modes associated with the signal and noise are adequately sampled by a (filled) vertical array, and potentially large if they are not. The difference is analyzed analytically and illustrated numerically using vertical arrays in an Arctic and Pacific environment. Array gain and peak‐to‐sidelobe ratio are evaluated for the MFP and EIG processors under identical environmental conditions, and compared with the matched‐mode processing assuming perfect mode decomposition. Examples are given to illustrate the use of mode filtering to suppress the sidelobes caused by sound‐speed mismatch in the upper ( more...
- Published
- 1990
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164. Modal shading coefficients for high‐resolution source depth localization
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T. C. Yang
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Minimum-variance unbiased estimator ,Signal-to-noise ratio ,Modal ,Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Aperture ,Normal mode ,Acoustics ,Function (mathematics) ,Shading ,Image resolution ,Mathematics - Abstract
In this article the minimum variance principle is applied to the modal shading coefficients to improve source depth localization. It is shown that for a long, well‐populated vertical array, the source depth localization function based on the minimum variance principle is approximately the same as the depth function based on normal mode theory. For a limited aperture vertical array, the modes are spatially undersampled. In this case, the modal shading coefficients based on the minimum variance principle are shown to significantly improve the depth resolution assuming sufficient signal‐to‐noise ratio. But, as the signal‐to‐noise ratio decreases, the depth resolution for the minimum variance case approaches the (conventional) modal beamformer result. more...
- Published
- 1990
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165. Zantedeschia mild mosaic virus, a new widespread virus in calla lily, detected by ELISA, dot-blot hybridization and IC-RT-PCR
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Chen Han Huang, Wen-Chi Hu, Ya-Chun Chang, and T.-C. Yang
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Antiserum ,biology ,Calla ,Potyvirus ,Dot blot ,Plant Science ,Horticulture ,biology.organism_classification ,Virology ,Molecular biology ,Virus ,Reverse transcription polymerase chain reaction ,Capsid ,Genetics ,Agronomy and Crop Science ,Zantedeschia - Abstract
A new potyvirus, Zantedeschia mild mosaic virus (ZaMMV), was recently identified in calla lily ( Zantedeschia spp.) in Taiwan. The sequenced 3 ′ -terminal region indicated a unique amino acid sequence of ZaMMV, the N terminus of the capsid protein (CP), containing 39 glutamine residues before the DAG motif. In order to obtain antiserum for subsequent studies, a recombinant ZaMMV CP without polyglutamine was successfully expressed in Escherichia coli and used as the antigen. The specificity of ZaMMV antiserum was confirmed by immunoblot and ELISA analyses. Three detection methods, ELISA, dot-blot hybridization and immunocapture reverse transcription PCR (IC-RT-PCR), were developed and were able to detect ZaMMV successfully. During 2003‐2004 field surveys, the results demonstrated that ZaMMV, as well as Zantedeschia mosaic virus (ZaMV), are prevalent in calla-growing areas. In contrast, infection by Dasheen mosaic virus (DsMV), the most important virus of aroid plants, decreased dramatically because DsMV-free calla lily seedlings were grown in the field. Accordingly, the detection methods developed in this study will be useful in studying ZaMMV and also in producing ZaMMV-free calla lilies. more...
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- 2007
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166. Development of a reaction drive for a propulsion mechanism
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Samuel Oliver Wane, Hongnian Yu, and T C Yang
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Mechanism (engineering) ,Engineering ,Medical robotics ,business.industry ,media_common.quotation_subject ,Robot ,Mechanism based ,Control engineering ,Propulsion ,business ,Inertia ,media_common - Abstract
A micro robot that can be swallowed with sensors to inspect the intestine without the need to cut open a patient must have a propulsion mechanism to direct it to the areas of interest. The use of a propulsion mechanism external to the pill could endanger the patient, what is proposed here is a method of propelling a micro (capsule) robot with an internal mechanism based on the inertia of a swinging mass. The dynamics and control issues of a pendulum-driven cart-pole system are similar to those of a capsule robot. Therefore, this paper reports an experimental study of a pendulum-driven cart-pole system. The experimental results demonstrate the proposed system. more...
- Published
- 2007
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167. Environmental Effects On Phase Coherent Underwater Acoustic Communications: A Perspective From Several Experimental Measurements
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T. C. Yang
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Engineering ,Coherence time ,business.industry ,Acoustics ,Phase (waves) ,Internal wave ,Computer Science::Robotics ,Wind wave ,Underwater ,business ,Underwater acoustics ,Physics::Atmospheric and Oceanic Physics ,Underwater acoustic communication ,Coherence (physics) - Abstract
This paper presents a summary of results from several experiments using phase coherent underwater acoustic communications in shallow waters with weak to strong internal waves. Measurements of temporal coherence time of the underwater acoustic channels are presented and related to the equalizer performance. more...
- Published
- 2004
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168. High-Frequency FH-FSK Underwater Acoustic Communications: The Environmental Effect and Signal Processing
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Wen‐Bin Yang and T. C. Yang
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Beamforming ,Engineering ,Signal processing ,Frequency-shift keying ,business.industry ,Acoustics ,Bandwidth (signal processing) ,Bit error rate ,Electronic engineering ,Antenna diversity ,business ,Multipath propagation ,Underwater acoustic communication - Abstract
This paper analyzes the environmental effect and signal processing approaches for frequency‐hopped frequency‐shift‐keyed (FH FSK) underwater acoustic communications based upon data collected in two experiments: the RDS4 experiment near Halifax, Canada and MREA03 experiment near Elba, Italy. The FH FSK signals have a bandwidth of 4 kHz centered at 17 and 20 kHz. The source was lowed at ∼4 knots. The signals were received on a vertical line array anchored to the bottom. The acoustic environments at both sites have the same downward refractive sound speed profiles but very different bottom properties. The multipath spread last ∼20 msec in the MREA03 experiment and is > 1 sec in the RDS4 experiment. The different lengths of multipath delays have a significant effect on the bit error rate (BER) and the appropriate signal processing needed to reduce the BER. We present the data analysis results, the signal processing approaches, including multi‐channel beamforming and spatial diversity combining, and discuss the implications for the use of FH‐FSK for multi‐user communications. more...
- Published
- 2004
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169. Environmental and Motion Effects on Orthogonal Frequency Division Multiplexed On-Off Keying
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Paul J. Gendron and T. C. Yang
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Physics ,Frequency response ,Orthogonal frequency-division multiplexing ,On-off keying ,Frequency domain ,Electronic engineering ,Fading ,Center frequency ,Amplitude-shift keying ,Phase-shift keying - Abstract
Orthogonal frequency division multiplexing with on‐off keying (OFDM‐OOK) offers a means to near BPSK signaling rates with the simplicity of non‐coherent processing. At high frequencies source receiver acceleration induces time varying signal dilations that adversely effect both frequency alignment and multicarrier orthogonality. Dilation process estimation is coupled with a decision directed frequency domain channel magnitude response estimator for non‐coherent equalization of OFDM‐OOK. Joint co‐channel estimation is presented for near optimal decisions under loss of orthogonality due to Doppler spreading. Data from a moving source experiment at ranges from .8 km to 2.0 km, conducted in the shallow water off the coast of Elba Italy were used to test the feasibility of OFDM‐OOK at 18kHz center frequency with 4 kHz bandwidth. The effects of source receiver relative motion, frequency selectivity, and Doppler spreading on bit error rates were assessed. Mollification of frequency selective fading by diversity ... more...
- Published
- 2004
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170. Underwater Acoustic Communication Channel Capacity: A Simulation Study
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Thomas J. Hayward and T. C. Yang
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Engineering ,Channel capacity ,business.industry ,Acoustics ,Bandwidth (signal processing) ,Broadband ,Internal wave ,business ,Sonar ,Wind speed ,Underwater acoustic communication ,Computer Science::Information Theory ,Communication channel - Abstract
Acoustic communication channel capacity determines the maximum data rate that can be supported (theoretically) by an acoustic channel for a given source power and source/receiver configuration. In this paper, broadband acoustic propagation modeling is applied to estimate the channel capacity of a shallow water waveguide for a single source‐receiver pair, both with and without source bandwidth constraints. Initial channel capacity estimates are obtained for a range‐independent environment defined by the mean (time‐averaged) sound speed profile measured at a site in the 1995 SWARM experiment. Without bandwidth constraints, estimated channel capacities approach 10 megabits per second at 1 km range, but after 2 km range they decay at a rate consistent with that of estimates by Peloquin and Leinhos, which were based on a sonar equation analysis for a generic underwater channel. Channel capacities subject to source bandwidth constraints are approximately 30 90% lower than the upper bounds predicted by the sonar equation analysis, and exhibit a significant wind speed dependence. Simulations of internal wave effects on channel capacity show minimal effects at low frequencies but, at 2500 Hz, show a significant increase in the channel capacity at longer ranges. Implications for underwater acoustic communication systems are discussed. more...
- Published
- 2004
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171. Chromosome alteration in the progression to immortality of human epithelial cells irradiated by heavy ions
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M. Durante, G. Gialanella, T. C. Yang, GROSSI, GIANFRANCO, M., Durante, Grossi, Gianfranco, G., Gialanella, and T. C., Yang
- Published
- 1993
172. Conjugate Reduction of α,β-Unsaturatedp-Toluenesulfonylhydrazones to Alkenes with Catecholborane: 5β-Cholest-3-Ene
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Robert O. Hutchins, Nicholas R. Natale, Dominic T. C. Yang, Vicky Broach, and George W. Kabalka
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chemistry.chemical_compound ,chemistry ,Product (mathematics) ,Imine ,Organic chemistry ,Catecholborane ,Ene reaction ,Enamine ,Conjugate - Abstract
Conjugate reduction of α,β-unsaturated p-toluenesulfonylhydrazones to alkenes with catecholborane: 5β-cholest-3-ene intermediate: cholest-4-en-3-one p-toluenesulfonylhydrazone product: 5β-cholest-3-ene product: C6H5CH2CHCHCH3 product: C6H5CH2CHCH2 product: (CH3)2CHCHCHCH3 product: CH3(CH2)3CHCCHCH3 product: CH3CHCCHC6H5 byproduct: 5β-cholestane byproduct: 5α-cholestane byproduct: 5α-cholest-3-ene Keywords: enamine or imine formation; rearrangements; reduction, miscellaneous more...
- Published
- 2003
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173. Motion compensation for adaptive horizontal line array processing
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T. C. Yang
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Beamforming ,Acoustics and Ultrasonics ,business.industry ,Acoustics ,Array processing ,Signal ,Space-time adaptive processing ,Optics ,Arts and Humanities (miscellaneous) ,Interference (communication) ,Sensor array ,Array gain ,business ,Adaptive beamformer ,Mathematics - Abstract
Large aperture horizontal line arrays have small resolution cells and can be used to separate a target signal from an interference signal by array beamforming. High-resolution adaptive array processing can be used to place a null at the interference signal so that the array gain can be much higher than that of conventional beamforming. But these nice features are significantly degraded by the source motion, which reduces the time period under which the environment can be considered stationary from the array processing point of view. For adaptive array processing, a large number of data samples are generally required to minimize the variance of the cross-spectral density, or the covariance matrix, between the array elements. For a moving source and interference, the penalty of integrating over a large number of samples is the spread of signal and interference energy to more than one or two eigenvalues. The signal and interference are no longer clearly identified by the eigenvectors and, consequently, the ability to suppress the interference suffers. We show in this paper that the effect of source motion can be compensated for the (signal) beam covariance matrix, thus allowing integration over a large number of data samples without loss in the signal beam power. We employ an equivalent of a rotating coordinate frame to track the signal bearing change and use the waveguide invariant theory to compensate the signal range change by frequency shifting. more...
- Published
- 2003
174. Genetic changes in mammalian cells transformed by helium ions
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M. Durante, T. C. Yang, R. Roots, GROSSI, GIANFRANCO, M., Durante, Grossi, Gianfranco, T. C., Yang, and R., Roots
- Published
- 1992
175. [Clinical research on arteriovenous internal fistula made by various blood vessels]
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W Q, Zhong, T C, Yang, and L Q, Yu
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Adult ,Male ,Adolescent ,Prostheses and Implants ,Middle Aged ,Blood Vessel Prosthesis Implantation ,Glomerulonephritis ,Renal Dialysis ,Arteriovenous Fistula ,Radial Artery ,Arm ,Humans ,Kidney Failure, Chronic ,Female ,Polytetrafluoroethylene ,Aged - Abstract
To compare the permeability and incidence rate of complication of arteriovenous internal fistula made by autogenous, homologous, and artificial Teflon blood vessels.Two hundred and forty one cases with arteriovenous internal fistula made by autogenous, homologous, and artificial Teflon blood vessels were followed up to compare the permeability and incidence rate of complication at 6 months, 1 year, 3 years, and 5 years.The incidence rate of complication of autogenous blood vessels was lowest, it had no statistical differences compared with arteriovenous internal fistula made by homologous blood vessels. The permeability of arteriovenous internal fistula made by homologous blood vessels was highest, and it had no statistical differences compared with autogenous blood vessels. The permeability of arteriovenous internal fistula made by artificial Teflon blood vessels was lowest, but the incidence rate of complication was highest, and it had significantly statistical differences compared with arteriovenous internal fistula made by autogenous blood vessels (P0.01).Arteriovenous internal fistulas made by autogenous and homologous blood vessels have high permeability and low incidence rate of complication, they are superior to the arteriovenous internal fistula made by artificial Teflon blood vessels. more...
- Published
- 2002
176. Estimate of the frequency of true incomplete exchanges in human lymphocytes exposed to 1 GeV/u Fe ions in vitro
- Author
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H. Wu, Kerry George, and T. C. Yang
- Subjects
Genetics ,Chromosome Aberrations ,Radiological and Ultrasound Technology ,medicine.diagnostic_test ,Iron ,Gamma ray ,Linear energy transfer ,Biology ,Molecular biology ,In vitro ,Telomere ,Ionizing radiation ,Fluorescent labelling ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Female ,Linear Energy Transfer ,Lymphocytes ,Radiation injury ,In Situ Hybridization, Fluorescence ,Fluorescence in situ hybridization - Abstract
PURPOSE: To study the frequency of true incomplete exchanges induced by high-LET radiation. MATERIALS AND METHODS: Human lymphocytes were exposed to 1 GeV/u Fe ions (LET = 140 keV/microm). Chromosome aberrations were analysed by a fluorescence in situ hybridization using a combination of whole-chromosome-specific probes and human telomere probes. Chromosomes 1, 3 and 4 were investigated. RESULTS: The percentage of incomplete exchanges was between 23 and 29% if telomere signals were not considered. The percentage decreased to approximately 10% after ruling out false incomplete exchanges containing telomere signals. The final estimation of true incomplete exchanges was more...
- Published
- 2001
177. Accuracy of sonography in predicting the outcome of fetal congenital diaphragmatic hernia
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Y Y, Hsieh, F C, Chang, H D, Tsai, T Y, Hsu, and T C, Yang
- Subjects
Hernia, Diaphragmatic ,Pregnancy ,Pregnancy Outcome ,Humans ,Female ,Hernias, Diaphragmatic, Congenital ,Ultrasonography, Prenatal - Abstract
The outcome of congenital diaphragmatic hernia (CDH) remains poor despite recent advances in neonatal care. This study was designed to evaluate the role of sonography in predicting the outcome of CDH.Pregnancies with CDH were studied. Fetal survival, morbidity, combined anomalies and mortality were recorded. Seven parameters were recorded, including the presence of hydramnios, side of herniation, cardiac deviation, stomach presence, gestational age at the time of finding the CDH and time of postpartum herniorrhaphy. The predictive values of these parameters for fetal outcome were analyzed.A total of 31 pregnancies were studied. There were 11 cases (35.5%) of termination, seven cases (22.6%) of perinatal death, four cases (12.9%) of late death and nine cases of survival (29%). The survivor group included four cases (44.4%) of complete recovery and five cases (55.6%) with persistent morbidity. There were 15 cases of simple CDH including eight cases of cardiac anomalies (ventricular-septal defect, atrial-septal defect, patent ductus arteriosus and ventricular dilatation). There were eight cases with severe anomalies (3 with trisomy 18, 2 with Cantrell's pentalogy, 1 with trisomy 13, 1 with cystic hygroma and one with Tetralogy Fallot). Among the seven parameters studied, gestational age at the time of finding the CDH and hydramnios were related to fetal survival.Sonography assists in predicting the postnatal outcome of CDH. Diagnosis of CDH at less than 25 weeks' gestation and the existence of hydramnios are associated with higher mortality. Postnatal therapy and prenatal surgical intervention are necessary to salvage fetuses in the presence of these two situations. The survival rate of infants with CDH was 45%. Of these, 55.6% had persistent morbidity. Prenatal counseling should reflect this. more...
- Published
- 2000
178. Gender prevalence in twin-twin transfusion syndrome
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Y Y, Hsieh, F C, Chang, H D, Tsai, T Y, Hsu, T C, Yang, L S, Yeh, and W C, Chang
- Subjects
Male ,Sex Factors ,Pregnancy ,Infant, Newborn ,Prevalence ,Taiwan ,Humans ,Female ,Fetofetal Transfusion - Abstract
This study aimed to determine the gender prevalence of fetuses complicated with twin-twin transfusion syndrome (TTTS).All cases of TTTS corresponded with the following major criteria: a single placenta, monochorion, the same gender, and a combination of polyhydramnios-oligohydramnios. At least one of three minor criteria were required for the establishment of TTTS, including a stuck twin, a birth weight discordance exceeding 20%, and hemoglobin difference5 g/dl.Fifty-six twin pregnancies met the above criteria, of which 33 (58.9%) twin pairs were female. The female tendency existed, but there was a non-significant difference. Mean gestational age at diagnosis was 20.2 +/- 3.2 weeks. The birth weight discordance exceeding 20% was present in 50 of 56 (89.3%), and mean growth discordance was 32% +/- 8%. A stuck twin was noted in 37 of 56 cases (66.1%). The mortality of fetuses or neonates was 34.8% (39/112), including 8 (7.1%) fetal deaths and 31 (27.6%) neonatal deaths. There were no differences in maternal age, parity, or gestational age of delivery between male and female pregnancies.Although the female preponderance did not reach statistical significance, the female tendency might still exist after a larger series analysis. The female tendency may be the result of the gender difference in monochorionic twins. The gender difference could provide research implications and a diagnostic warning for clinicians in monochorionic twin pregnancies before the presence of TTTS. more...
- Published
- 2000
179. Precipitate delivery and postpartum hemorrhage after term induction with 200 micrograms misoprostol
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Y Y, Hsieh, H D, Tsai, C C, Chang, L S, Yeh, T C, Yang, and T Y, Hsu
- Subjects
Adult ,Pregnancy ,Oxytocics ,Postpartum Hemorrhage ,Humans ,Female ,Misoprostol ,Obstetric Labor Complications - Abstract
Misoprostol has been widely applied in early pregnancy termination and term pregnancy induction. However, the upper dosage limit of misoprostol through vaginal route has not been firmly established. Most popular dosages of vaginal misoprostol recommended are 25, 50 or 100 micrograms. There are no reports on the dangers of high-dosage misoprostol 200 micrograms as used in term labor induction. We present a primiparaous woman who was administered 200 micrograms misoprostol vaginally for term labor induction. The following precipitate delivery resulted in multiple lacerations of the isthmus, cervix and vagina, postpartum hemorrhage and disseminated intravascular coagulopathy. Inevitably, a hysterectomy was performed. A postsurgical check of the uterus confirmed lacerations of the isthmus and internal cervix. This rare complication suggests the possible dangers of vaginal misoprostol doses as high as 200 micrograms for term induction of labor at term. more...
- Published
- 2000
180. The prenatal diagnosis of Pierre-Robin sequence
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Y Y, Hsieh, C C, Chang, H D, Tsai, T C, Yang, C C, Lee, and C H, Tsai
- Subjects
Counseling ,Male ,Pierre Robin Syndrome ,Pregnancy ,Infant, Newborn ,Humans ,Abnormalities, Multiple ,Female ,Ultrasonography, Prenatal - Abstract
The purpose of this study was to evaluate the spectrum of prenatal sonographic and chromosomal findings, associated anomalies and perinatal and neonatal outcomes in cases with Pierre-Robin sequence. All cases (20) with Pierre Robin sequence, who were born at China Medical College Hospital between 1990 and 1997, were included and analysed in this series. 12 pregnancies (60 per cent) were complicated by polyhydramnios and 9 (45 per cent) were combined with cleft palate. Four cases (20 per cent) with cardiac anomalies were also observed. Two fetuses (10 per cent) had abnormal karyotyping (one trisomy 21, one trisomy 18). All fetuses were delivered at or near term. Male deviation was observed in cases with isolated Pierre-Robin sequence or combined mild anomalies (male female ratio: 13:3). Two neonatal mortalities and three with mental retardation were observed. This investigation provides a basis for counselling patients with fetal micrognathia or neonatal Pierre-Robin sequence. The main prenatal sonographic findings of Pierre-Robin sequence are micrognathia, polyhydramnios and cleft palate. In cases of polyhydramnios, sonographic examination of the facial profile and palate are recommended. After the finding of polyhydramnios, micrognathia, and even cleft palate, clinicians should be aware of the possibility of neonatal Pierre-Robin sequence. Cardiac evaluation and karyotyping is also recommended. more...
- Published
- 1999
181. Theoretical and experimental tests of a chromosomal fingerprint for densely ionizing radiation based on F ratios calculated from stable and unstable chromosome aberrations
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J N, Lucas, W, Deng, S W, Oram, F S, Hill, M, Durante, K, George, H, Wu, C L, Owens, and T C, Yang
- Subjects
Chromosome Inversion ,Chromosomes, Human ,Humans ,Dose-Response Relationship, Radiation ,Linear Energy Transfer ,Lymphocytes ,DNA Fingerprinting ,Cells, Cultured ,In Situ Hybridization, Fluorescence ,Translocation, Genetic - Abstract
In the present study, F ratios for both stable chromosome aberrations, i.e. ratios of translocations to pericentric inversions, and unstable aberrations, i.e. dicentrics and centric rings, were measured using fluorescence in situ hybridization. F ratios for stable aberrations measured after exposure to low (2.89 Gy 60Co gamma rays) and high-LET (0.25 Gy 56Fe ions; 1.25 Gy 56Fe ions; 3.0 Gy 12C ions) radiation were 6.5 +/- 1.5, 4.7 +/- 1.6, 9.3 +/- 2.5 and 10.4 +/- 3.0, respectively. F ratios for unstable aberrations measured after low (2.89 Gy 60Co gamma rays) and high-LET (0.25 Gy 56Fe ions; 3.0 Gy 12C ions) radiations were 6.5 +/- 1.6, 6.3 +/- 2.3 and 11.1 +/- 3.7, respectively. No significant difference between the F ratios for low- and high-LET radiation was found. Further tests on the models for calculation of the F ratio proposed by Brenner and Sachs (Radiat. Res. 140, 134-142, 1994) showed that the F ratio may not be straightforward as a practical fingerprint for densely ionizing radiation. more...
- Published
- 1999
182. Succinylcholine-induced cardiac arrest in unsuspected becker muscular dystrophy--a case report
- Author
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C C, Wu, C S, Tseng, C H, Shen, T C, Yang, K P, Chi, and W M, Ho
- Subjects
Male ,Child, Preschool ,Neuromuscular Depolarizing Agents ,Humans ,Hyperkalemia ,Succinylcholine ,Muscular Dystrophies ,Heart Arrest - Abstract
A five year-old boy undergoing elective tonsillectomy sustained cardiac arrest following the administration of a single dose of succinylcholine during induction of anesthesia. With a 10-minute cardiopulmonary resuscitation (CPR) during which intravenous calcium gluconate, epinephrine, and sodium bicarbonate were given and DC counter shock applied, we were successful to restore cardiac activity without neurological sequelae. The cause of cardiac arrest we speculated was hyperkalemia, possibly secondary to succinylcholine-induced rhabdomyolysis. It is suggested that succinylcholine should not be used in patients with known or suspected muscular dystrophy. more...
- Published
- 1999
183. Unexpected pheochromocytoma--a case report of anesthesia in a uremic patient
- Author
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Y C, Huang, T C, Yang, and W M, Ho
- Subjects
Adult ,Male ,Adrenal Gland Neoplasms ,Humans ,Anesthesia ,Pheochromocytoma ,Uremia - Abstract
Pheochromocytoma is an uncommon neoplasm causing blood pressure changes. It may go undiagnosed in uremic patients in whom hypertension is common. The preferential diagnostic work-up, including urine and serum catecholamine measurements, is unsuitable for uremic patients due to anuria and inherent increases in serum catecholamine levels. Here, we present a case of uremia, scheduled for right adrenalectomy and simple nephrectomy, who had been sustaining hypertension. Malignant hypertension was only discovered during surgical manipulation of the adrenal tumor. Pheochromocytoma was highly suspected. The patient was treated with nitroglycerin, fentanyl, and increased concentration of isoflurane to deepen the anesthesia. However, the results were only fair and after ligation of the tumor veins, hypotension ensued. Pathological examination verified the diagnosis of pheochromocytoma. In reviewal of the whole course of treatment, it was considered that the placement of a pulmonary artery catheter to detect volume shifts and changes in hemodynamic status was indicated. Related papers were reviewed and application of diagnostic tools and their limitations, safety and efficacy of anesthetics and vasodilators, and possible complications relevant to management of pheochromocytoma were also discussed. In conclusion, it is important to remain alert, administer agents cautiously, and set up complete monitoring if needed, and carry out postoperative intensive care to lessen complications in the anesthetic management of this rare and dangerous incidentaloma encountered during anesthesia. more...
- Published
- 1999
184. Cellular Responses
- Author
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H. Rink, T. C. Yang, L. Böhm, R. Govorun, D. Häder, G. Horneck, B. Kaina, S. Kozubek, S. Z. Liu, C. Potten, and L. Ptitsyn
- Published
- 1999
- Full Text
- View/download PDF
185. Prenatal diagnosis of Apert syndrome
- Author
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C C, Chang, F J, Tsai, H D, Tsai, C H, Tsai, Y Y, Hseih, C C, Lee, T C, Yang, and J Y, Wu
- Subjects
Adult ,Male ,Pregnancy ,Prenatal Diagnosis ,DNA Mutational Analysis ,Amniocentesis ,Humans ,Female ,Acrocephalosyndactylia ,Polymerase Chain Reaction ,Receptors, Fibroblast Growth Factor ,Ultrasonography, Prenatal - Abstract
Apert syndrome (AS) is clinically characterized by typical facial features and symmetrical syndactyly of the digits. AS is inherited as an autosomal dominant trait. Recently, a fibroblast growth factor receptors 2 (FGFR2) mutation, either C934G or C937G, was identified in exon IIIa. Our report documents an affected mother and son in whom one of the two mutations in AS had occurred sporadically in the mother. The diagnosed of AS was based on associated abnormal physical features and on molecular genetic analysis. A C-to-G transversion at position 937 of the cDNA resulting in a proline-to-arginine substitution at codon 259 was found in the mother. In her second pregnancy, prenatal diagnosis by both restriction analysis and direct sequencing was undertaken and this showed that the female fetus had not inherited the mutation. more...
- Published
- 1998
186. Estimate of true incomplete exchanges using fluorescence in situ hybridization with telomere probes
- Author
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Kerry George, T. C. Yang, and H. Wu
- Subjects
In situ ,Genetics ,Chromosome Aberrations ,Radiological and Ultrasound Technology ,medicine.diagnostic_test ,Hybridization probe ,Lymphocyte ,Chromosome ,Biology ,Telomere ,Molecular biology ,medicine.anatomical_structure ,medicine ,%22">Fish ,Chromosomes, Human ,Humans ,Radiology, Nuclear Medicine and imaging ,Female ,Lymphocytes ,DNA Probes ,In Situ Hybridization, Fluorescence ,Gamma irradiation ,Fluorescence in situ hybridization - Abstract
PURPOSE: To study the frequency of true incomplete exchanges in radiation-induced chromosome aberrations. MATERIALS AND METHODS: Human lymphocytes were exposed to 2 Gy and 5 Gy of gamma-rays. Chromosome aberrations were studied using the fluorescence in situ hybridization (FISH) technique with whole chromosome-specific probes, together with human telomere probes. Chromosomes 2 and 4 were chosen in the present study. RESULTS: The percentage of incomplete exchanges was 27% when telomere signals were not considered. After excluding false incomplete exchanges identified by the telomere signals, the percentage of incomplete exchanges decreased to 11%. Since telomere signals appear on about 82% of the telomeres, the percentage of true incomplete exchanges should be even lower and was estimated to be 3%. This percentage was similar for chromosomes 2 and 4 and for doses of both 2 Gy and 5 Gy. CONCLUSIONS: The percentage of true incomplete exchanges is significantly lower in gamma-irradiated human lymphocytes than the frequencies reported in the literature. more...
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- 1998
187. Rupture of rudimentary horn pregnancy: a case report
- Author
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Y Y, Hsieh, C C, Chang, H D, Tsai, T H, Chiu, T C, Yang, and T Y, Hsu
- Subjects
Adult ,Uterine Rupture ,Pregnancy ,Humans ,Female ,Pregnancy, Ectopic - Abstract
A rare case of rupture of a noncommunicating rudimentary horn pregnancy is presented. The pregnancy continued to 16-weeks' gestation, when the rudimentary horn ruptured. The patient had signs and symptoms of massive hemoperitoneum. An emergency exploratory laparotomy revealed a ruptured rudimentary horn and an intact amnionic sac. Prompt excision of the rudimentary horn was performed. The relative literature and factors associated with a rudimentary horn pregnancy are reviewed and discussed. more...
- Published
- 1998
188. Intramural pregnancy with negative maternal serum beta-hCG. A case report
- Author
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Y Y, Hsieh, C C, Chang, H D, Tsai, L S, Yeh, T Y, Hsu, and T C, Yang
- Subjects
Adult ,Pregnancy ,Humans ,Chorionic Gonadotropin, beta Subunit, Human ,Female ,Dilatation and Curettage ,Pregnancy, Ectopic ,Ultrasonography - Abstract
Intramural pregnancy is the rarest form of ectopic pregnancy. The diagnosis depends upon the sonographic finding of intramural gestational sac-like growth and persistent high beta-human chorionic gonadotropin (beta-hCG) levels after dilatation and curettage. No authors mentioned negative beta-hCG result in such situation. Rarely has the literature contained preoperative sonograms and photographs of postoperative gestational tissue.A 31-year-old woman presented with vaginal spotting for five months. Six months earlier she underwent dilatation and curettage for blighted ovum at 8 weeks' gestation. Since then, incidental vaginal spotting was noted. Sonography demonstrated an intramural cyst with fetal pole-like growth. Serum beta-hCG, diagnostic dilatation and curettage, and hysteroscopic examination were negative. Laparotomy for excision of the cyst confirmed an intramural pregnancy.Because of the long period after fetal wastage, negative serum beta-hCG was noted in this case. Negative serum beta-hCG was unreliable in the exclusion of intramural pregnancy. With the sonographic appearance of intramural gestational sac-like growth, in spite of a negative serum beta-hCG the clinician should be alert to the possibility of intramural pregnancy. more...
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- 1998
189. Acute pancreatitis in pregnancy
- Author
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C C, Chang, Y Y, Hsieh, H D, Tsai, T C, Yang, L S, Yeh, and T Y, Hsu
- Subjects
Adult ,Pregnancy Complications ,Pancreatitis ,Pregnancy ,Acute Disease ,Humans ,Female - Abstract
Acute pancreatitis in pregnancy is rare. Our purpose in this study was to discuss the etiology, incidence and course of pancreatitis in pregnancy and to evaluate the maternal and perinatal outcomes.Pregnant women with pancreatitis admitted to China Medical College Hospital, Taiwan, from 1980 to 1995 were studied retrospectively. A total of 16 patients were enrolled in the study. Two patients had gallstones and hyperlipidemia; four had gallstones alone; seven had hyperlipidemia alone; one had gestational diabetes mellitus; one had hyperparathyroidism and pregnancy-induced hypertension alone; and one had Hashimoto's thyroiditis. Conservative treatment and low-fat diets were administered to the patients.The incidence of gestational pancreatitis in this series was one in 6,790 pregnancies. The fetal outcome included eight preterm deliveries and three fetal losses. There were no maternal mortalities. The etiologies of pancreatitis were primary hyperlipidemia (56.3%) and gallstones (37.5%). All patients responded favorably to supportive therapy, and most of the symptoms subsided after delivery.Early diagnosis and treatment is of utmost importance in the management of acute pancreatitis in pregnancy. The results of this study showed good maternal outcome following appropriate treatment. Fetal prognosis was less favorable and was most often associated with hyperlipidemia. Fetal monitoring is essential during the management of pancreatitis in pregnancy. more...
- Published
- 1998
190. Radiation-induced total-deletion mutations in the human hprt gene: a biophysical model based on random walk interphase chromatin geometry
- Author
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Rainer K. Sachs, T. C. Yang, and H. Wu
- Subjects
Hypoxanthine Phosphoribosyltransferase ,Biophysics ,Biology ,medicine.disease_cause ,Biophysical Phenomena ,chemistry.chemical_compound ,Chromosome Walking ,Centromere ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Linear Energy Transfer ,Gene ,Interphase ,Mathematical Computing ,Cells, Cultured ,Genetics ,Mutation ,Radiological and Ultrasound Technology ,Models, Genetic ,Chromosome ,DNA ,Fibroblasts ,Chromatin ,enzymes and coenzymes (carbohydrates) ,chemistry ,Essential gene ,Gene Deletion ,DNA Damage - Abstract
PURPOSE: To develop a biophysical model that explains the sizes of radiation-induced hprt deletions. METHODS: Key assumptions: (1) Deletions are produced by two DSB that are closer than an interaction distance at the time of DSB induction; (2) Interphase chromatin is modelled by a biphasic random walk distribution; and (3) Misrejoining of DSB from two separate tracks dominates at low-LET and misrejoining of DSB from a single track dominates at high-LET. RESULTS: The size spectra for radiation-induced total deletions of the hprt gene are calculated. Comparing with the results of Yamada and coworkers for gamma-irradiated human fibroblasts the study finds that an interaction distance of 0.75 microm will fit both the absolute frequency and the size spectrum of the total deletions. It is also shown that high-LET radiations produce, relatively, more total deletions of sizes below 0.5 Mb. The model predicts an essential gene to be located between 2 and 3 Mb from the hprt locus towards the centromere. Using the same assumptions and parameters as for evaluating mutation frequencies, a frequency of intra-arm chromosome deletions is calculated that is in agreement with experimental data. CONCLUSIONS: Radiation-induced total-deletion mutations of the human hprt gene and intrachange chromosome aberrations share a common mechanism for their induction. more...
- Published
- 1998
191. Rejoining and misrejoining of radiation-induced chromatin breaks. III. Hypertonic treatment
- Author
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M, Durante, K, George, H L, Wu, and T C, Yang
- Subjects
Chromosome Aberrations ,Saline Solution, Hypertonic ,Cricetinae ,Animals ,Humans ,CHO Cells ,Lymphocytes ,Chromatin - Abstract
It has been shown that treatment in anisotonic medium modifies rejoining of radiation-induced breaks in interphase chromosomes. In previous work, we have demonstrated that formation of exchanges in human lymphocytes has a slow component (half-time of 1-2 h), but a fraction of exchanges are also observed in samples assayed soon after exposure. In this paper we studied the effect of hypertonic treatment on rejoining and misrejoining of radiation-induced breaks using fluorescence in situ hybridization of prematurely condensed chromosomes in human lymphocytes. Isolated lymphocytes were irradiated with 7 Gy gamma rays, fused to mitotic hamster cells and incubated in hypertonic solution (0.5 M NaCl) for the period normally allowed for interphase chromosome condensation to occur. The data from hypertonic treatment experiments indicate the presence of a class of interphase chromosome breaks that rejoin and misrejoin very quickly (half-time of 5-6 min). The fast misrejoining of these lesions is considered to be responsible for the initial level of exchanges which we reported previously. No significant effect of hypertonic treatment on the yield of chromosome aberrations scored at the first postirradiation mitosis was detected. more...
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- 1998
192. Rejoining and misrejoining of radiation-induced chromatin breaks. IV Charged particles
- Author
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M. DURANTE, Y. FURUSAWA, K. GEORGE, G. GIALANELLA, O. GRECO, N. MATSUFUJI, PUGLIESE, MARIAGABRIELLA, T. C. YANG, GROSSI, GIANFRANCO, Durante, M., Furusawa, Y., George, K., Gialanella, G., Greco, O., Grossi, Gianfranco, Matsufuji, N., Pugliese, Mariagabriella, and Yang, T. C. more...
- Published
- 1998
193. Biodosimetry results from space flight Mir-18
- Author
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T C, Yang, K, George, A S, Johnson, and M, Durante
- Subjects
Chromosome Aberrations ,Radiation Monitoring ,Astronauts ,Humans ,Lymphocytes ,Space Flight ,Radiation Dosage ,Sister Chromatid Exchange ,In Situ Hybridization, Fluorescence ,Russia - Abstract
Astronauts are classified as radiation workers due to the presence of ionizing radiation in space. For the assessment of health risks, physical dosimetry has been indispensable. However, the change of the location of dosimeters on the crew members, the variation in dose rate with location inside the spacecraft and the unknown biological effects of microgravity can introduce significant uncertainties in estimating exposure. To circumvent such uncertainty, a study on the cytogenetic effects of space radiation in human lymphocytes was proposed and conducted for Mir-18, a 115-day mission. This study used fluorescence in situ hybridization (FISH) with whole-chromosome painting probes to score chromosomal exchanges and the Giemsa staining method to determine the frequency of dicentrics. The growth kinetics of cells and sister chromatid exchanges (SCEs) were examined to ensure that chromosomal aberrations were scored in the first mitosis and were induced primarily by space radiation. Our results showed that the frequency of chromosomal aberrations increased significantly in postflight samples compared to samples drawn prior to flight, and that the frequency of SCEs was similar for both pre- and postflight samples. Based on a dose-response curve for preflight samples exposed to gamma rays, the absorbed dose received by crew members during the mission was estimated to be about 14.75 cSv. Because the absorbed dose measured by physical dosimeters is 5.2 cGy for the entire mission, the RBE is about 2.8. more...
- Published
- 1997
194. Calculation of 6-hour D/P creatinine ratio from the 4-hour peritoneal equilibration test. The effect of dwell duration on the results
- Author
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R, Mehrotra, R, Khanna, T C, Yang, P, Kathuria, H L, Moore, B F, Prowant, K D, Nolph, and Z J, Twardowski
- Subjects
Adult ,Aged, 80 and over ,Male ,Polycystic Kidney Diseases ,Time Factors ,Diagnostic Tests, Routine ,Metabolic Clearance Rate ,Biological Transport, Active ,Reproducibility of Results ,Middle Aged ,Models, Theoretical ,Models, Biological ,Peritoneal Dialysis, Continuous Ambulatory ,Creatinine ,Dialysis Solutions ,Hypertension ,Humans ,Kidney Failure, Chronic ,Diabetic Nephropathies ,Female ,Peritoneum ,Aged - Abstract
Since the introduction of the peritoneal equilibration test (PET), the 4-hour dialysate/plasma creatinine (D/P Cr) has been used by several authors for determining continuous ambulatory peritoneal dialysis (CAPD) prescriptions. However, the results have been unsatisfactory because the 4-hr D/P Cr does not accurately reflect the D/P Cr in 24-hr collections. The PET and the 24-hr dialysate collections differ in the duration of dwell and the tonicity and volume of dialysate, all of which influence the equilibrated D/P Cr. It can be assumed that the D/P Cr in 24-hr collections in these patients is closer to a 6-hr D/P Cr. Because a 6-hr PET is inconvenient, we developed a mathematical model to calculate the 5- and 6-hr D/P using the results of a standard PET.In a retrospective analysis, D/P Cr ratios in 24-hr collections and D/P Cr ratios calculated from a mathematical formula were correlated. Using a mathematical model, the data collected fit an exponential relation of the type D/P = a(1-e-t/tau). The values of a and tau are unique for a given patient and were determined using a nonlinear regression technique. The formula performed well on our published data-the true and predicted 6-hr D/P Cr being 0.696 and 0.71, respectively.The University Hospital and Clinics, Dalton Cardiovascular Research Center and Dialysis Clinic, Inc., Columbia, Missouri.All CAPD patients on four 2-L exchanges/day at the time of the 24-hr collections were included.None.Closeness of 4-hr and 6-hr D/P Cr values to those of 24-hr ratios.The study group comprised 74 patients (age, mean +/- SEM: 56.4 +/- 1.8 yr) with 80 PETs and 145 (24-hr) collections. The interval between the two tests was 8.3 +/- 0.9 months (0-48.7 months). The median 24-hr D/P Cr of 0.760 did not differ significantly from the predicted median 6-hr D/P Cr of 0.755. A subgroup analysis, based on transport type, showed that this relationship was most precise in the high-average transporters. The predicted 6-hr D/P Cr was within 10% of the 24-hr D/P Cr in 48% of patients and within 20% in 77% of patients. The margin of error was greatest in the low transporters.To conclude, the 4-hr D/P Cr from a PET cannot be used interchangeably with the D/P Cr in the 24-hr dialysate collections, hence, the clearances calculated thereof will be inaccurate. Using the proposed model, it is feasible to use the 4-hr PET results to obtain 5- and 6-hr D/P Cr values. In our study, using this model, the extrapolated 6-hr D/P Cr is similar to the D/P Cr in 24-hr dialysate collections only in the high-average transporters. Hence, the best way to determine clearances in peritoneal dialysis patients is still by collecting 24-hr dialysates. more...
- Published
- 1997
195. Initiation of oncogenic transformation in human mammary epithelial cells by charged particles
- Author
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T C, Yang, K A, Georgy, and L M, Craise
- Subjects
Neoplasms, Radiation-Induced ,X-Rays ,Chromosome Breakage ,Genes, Recessive ,DNA ,Chromosomes ,Epithelium ,Translocation, Genetic ,Cell Line ,Cell Fusion ,Cell Transformation, Neoplastic ,Transformation, Genetic ,Gamma Rays ,Radiation, Ionizing ,Humans ,Female ,Genes, Tumor Suppressor ,Linear Energy Transfer ,Breast ,Chromosome Deletion ,Cells, Cultured ,Gene Deletion ,In Situ Hybridization, Fluorescence ,DNA Damage - Abstract
Experimental studies have shown that high linear-energy transfer (LET) charged particles can be more effective than x-rays and gamma-rays in inducing oncogenic transformation in cultured cells and tumors in animals. Based on these results, experiments were designed and performed with an immortal human mammary epithelial cell line (H184B5), and several clones transformed by heavy ions were obtained. Cell fusion experiments were subsequently done, and results indicate that the transforming gene(s) is recessive. Chromosome analysis with fluorescence in situ hybridization (FISH) techniques also showed additional translocations in transformed human mammary epithelial cells. In addition, studies with these cell lines indicate that heavy ions can effectively induce deletion, break, and dicentrics. Deletion of tumor suppressor gene(s) and/or formation of translocation through DNA double strand breaks is a likely mechanism for the initiation of oncogenic transformation in human mammary epithelial cells. more...
- Published
- 1997
196. Centric rings, acentric rings and excess acentric fragments based on a random-walk interphase chromosome model
- Author
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T. C. Yang, R. K. Sachs, H. Wu, M. Durante, H., Wu, Durante, Marco, and R. K., Sachs
- Subjects
Chromosome Aberrations ,Physics ,Radiological and Ultrasound Technology ,Mineralogy ,Interphase Chromosome ,Fibroblasts ,Random walk ,Chromosome aberration ,Molecular physics ,Acentric factor ,Acentric fragment ,Humans ,Linear Energy Transfer ,Radiology, Nuclear Medicine and imaging ,Interphase ,In Situ Hybridization, Fluorescence - Abstract
Excess acentric fragments, consisting of acentric rings and acentric linear fragments, are among the most frequent kinds of chromosome-type aberrations produced by radiation. The frequency of acentric rings cannot be obtained directly by experiment but is estimated here from the ratio of acentric to centric rings, evaluated using a random-walk model for the organization of chromatin during interphase and an assumption that the probability of an exchange formation is proportional to the rate of collision between two DSB. This ratio is calculated to be 2.5 in low-LET irradiated human fibroblasts, significantly greater than the ratio if proximity effects are not considered. The calculated frequency of acentric rings is insufficient to account for all the observed excess acentric fragments. Assuming that the rest of the excess acentric fragments are due to incomplete exchanges, all possible recombinations between two DSB that result in acentric rings and acentric linear fragments have been identified. From the chromosome aberration data, the incompleteness parameter has been estimated. Intra-arm chromosome exchanges, either complete or incomplete, were estimated to account for more than 50% of the excess acentric fragments in human fibroblasts. more...
- Published
- 1997
197. Cytogenetic effects of space radiation in lymphocytes of MIR-18 crews
- Author
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T C, Yang, K, George, A S, Johnson, A, Tavakoli, and M, Durante
- Subjects
Chromosome Aberrations ,Time Factors ,Models, Genetic ,Chromosome Breakage ,Space Flight ,Deuterium ,Radiation Dosage ,Helium ,Translocation, Genetic ,Chromosome Banding ,Mitotic Index ,Humans ,Lymphocytes ,Protons ,Sister Chromatid Exchange ,Cosmic Radiation ,Monitoring, Physiologic - Abstract
For assessing health risk, the measurement of physical dose received during a space mission, as well as the LETs, energies and charges of particles is important. It is also important to obtain quantitative information regarding the effectiveness of space radiation in causing damage to critical biological targets, e.g., chromosomes, since at present the estimated uncertainty of biological effects of space radiation is more than a factor of two. Such large uncertainty makes accurate health risk assessment very difficult. For this very reason, a study on cytogenetic effects of space radiation in human lymphocytes was proposed and done for MIR-18 mission. This study used FISH technique to score chromosomal translocations and C-banding method to determine dicentrics. Growth kinetics of cells and SCE were examined to ensure that chromosomal aberrations were scored in first mitosis and were induced not by chemical mutagens. Our results showed that chromosomal aberration frequency of post-flight samples was significantly higher than that of pre-flight ones and that SCE frequency was similar between pre- and post-flight samples. Based on a dose-response curve of preflight samples exposed to gamma rays, the absorbed dose received by crews during the mission was estimated to be about 14.5 cSv. Because the absorbed dose measured by physical dosimeters is 4.16 cGy for the entire mission, the RBE is about 3.5. more...
- Published
- 1997
198. Subbottom profiling using a ship towed line array
- Author
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Kwang Yoo, T. C. Yang, and Laurie T. Fialkowski
- Subjects
Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Acoustics ,Ambient noise level ,Inverse transform sampling ,Layer thickness ,Geology ,Line array ,Effective depth ,Controlled source - Abstract
This paper presents a technique for determining the effective depth of subbottom layers using a ship towed line array with a controlled source. Results are demonstrated using the MAPEX 2000 data. Local measurements of bottom layer thickness can be done using several methods: (1) Reflection profiling using a source and a receiver array at different ranges. (2) A high power downward looking boomer that can penetrate tens of meters of sediment layers. (3) A vertical line array using ambient noise. (4) Geo‐acoustic inversion using acoustic data from a ship towed line array. The ship towed line array provides local measurements of the subbottom thickness without the requirement of high power sources and extended experimental setup, on one hand, and with minimal interference from shipping traffic on the other hand. We show here that a simple seismic profiling technique extended to the towed line array data provides the same thickness profile as obtained by other techniques. It agrees with the geo‐acoustic inversion method but can be done in real time. Conversely, it can be used to initialize the geo‐acoustic inversion program. [Work supported by ONR.] more...
- Published
- 2004
- Full Text
- View/download PDF
199. Performance comparisons between passive‐phase conjugation and decision‐feedback equalizer for underwater acoustic communications
- Author
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T. C. Yang
- Subjects
Acoustics and Ultrasonics ,Computer science ,Equalizer ,Function (mathematics) ,Signal ,law.invention ,Noise ,Radio propagation ,Arts and Humanities (miscellaneous) ,law ,Nonlinear filter ,Bit error rate ,Phase conjugation ,Waveguide ,Algorithm ,Multipath propagation ,Impulse response ,Computer Science::Information Theory - Abstract
Passive‐phase conjugation (PPC) uses passive time reversal to remove intersymbol interferences (ISI) for acoustic communications in a multipath environment. It is based on the theory of signal propagation in a waveguide, which says that the Green function (or the impulse response function) convolved with its time‐reversed conjugate, summed over a large aperture vertical array of receivers is a delta function in space and time. A decision feedback equalizer (DFE) uses a nonlinear filter to remove ISI based on the minimum mean square errors (MSE) between the estimated and the true (or decision) symbols. These two approaches are motivated by different principles. In this paper, we analyze both using a common framework, illustrating the commonality and differences, pro and con between the two methods, and compare their performances in realistic ocean environments. The performance measures are MSE, output signal‐to‐noise ratio and bit error rate (BER) as a function of the number of receivers. For a small number of receivers, DFE outperforms PPC in all measures. As the number of receivers increases the BER for both processors approaches zero, but at a different rate. The results are supported by both simulated and real data. [Work supported by ONR.] more...
- Published
- 2004
- Full Text
- View/download PDF
200. Radiogenic cell transformation and carcinogenesis
- Author
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T C, Yang, K A, Georgy, M, Mei, and M, Durante
- Subjects
Mice, Inbred BALB C ,Mice, Inbred C3H ,Neoplasms, Radiation-Induced ,Weightlessness ,Radiobiology ,Dose-Response Relationship, Radiation ,Fibroblasts ,Space Flight ,Cell Line ,Rats ,Disease Models, Animal ,Mice ,Cell Transformation, Neoplastic ,Cricetinae ,Tumor Cells, Cultured ,Animals ,Humans ,Female ,Linear Energy Transfer ,Relative Biological Effectiveness - Abstract
Radiation carcinogenesis is one of the major biological effects considered important in the risk assessment for space travel. Various biological model systems, including both cultured cells and animals, have been found useful for studying the carcinogenic effects of space radiations, which consist of energetic electrons, protons and heavy ions. The development of techniques for studying neoplastic cell transformation in culture has made it possible to examine the cellular and molecular mechanisms of radiation carcinogenesis. Cultured cell systems are thus complementary to animal models. Many investigators have determined the oncogenic effects of ionizing and nonionizing radiation in cultured mammalian cells. One of the cell systems used most often for radiation transformation studies is mouse embryonic cells (C3H10T1/2), which are easy to culture and give good quantitative dose-response curves. Relative biological effectiveness (RBE) for heavy ions with various energies and linear energy transfer (LET) have been obtained with this cell system. Similar RBE and LET relationship was observed by investigators for other cell systems. In addition to RBE measurements, fundamental questions on repair of sub- and potential oncogenic lesions, direct and indirect effect, primary target and lesion, the importance of cell-cell interaction and the role of oncogenes and tumor suppressor genes in radiogenic carcinogenesis have been studied, and interesting results have been found. Recently several human epithelial cell systems have been developed, and ionizing radiation have been shown to transform these cells. Oncogenic transformation of these cells, however, requires a long expression time and/or multiple radiation exposures. Limited experimental data indicate high-LET heavy ions can be more effective than low-LET radiation in inducing cell transformation. Cytogenetic and molecular analyses can be performed with cloned transformants to provide insights into basic genetic mechanism(s) of radiogenic transformation of human epithelial cells. more...
- Published
- 1995
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