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A TWA Optical Receiver with Hybrid Integrated InP Detector
Hyeon Cheol Ki,Carl S.P. Chun,Joy Laskar,Nan Marie Jokerst,Martin A.Brooke,Yong-Sun Yoon,Jin Yeong Kang,Dong Sung Ma 한국정보과학회 1999 Journal of Electrical Engineering and Information Vol.4 No.6
To investigate the usefulness and feasibility of the TWA structure for low cost wide band system applications we designed a TWA optical receiver using low cost commercial process. The measured results show it is possible to achieve 18 ㎓ bandwidth with 7㏈ gain using low cost GaAs MESFET process with 20 ㎓ cut-off frequency. We also try, for the first time, the operation of an hybrid integrated OEIC using a fabricated TWA optical receiver and a thin film photo-detector 50㎛ in diameter. These results demonstrate that it is feasible to applicate TWA for the low cost wide band systems and to hybrid integrate wide band MMIC with thin film detectors for inexpensive high speed OEICs.
Extraction of Passive Device Model Parameters Using Genetic Algorithms
Yun, Il-Gu,Carastro, Lawrence A.,Poddar, Ravi,Brooke, Martin A.,May, Gary S.,Hyun, Kyung-Sook,Pyun, Kwang-Eui Electronics and Telecommunications Research Instit 2000 ETRI Journal Vol.22 No.1
The extraction of model parameters for embedded passive components is crucial for designing and characterizing the performance of multichip module (MCM) substrates. In this paper, a method for optimizing the extraction of these parameters using genetic algorithms is presented. The results of this method are compared with optimization using the Levenberg-Marquardt (LM) algorithm used in the HSPICE circuit modeling tool. A set of integrated resistor structures are fabricated, and their scattering parameters are measured for a range of frequencies from 45 MHz to 5 GHz. Optimal equivalent circuit models for these structures are derived from the s-parameter measurements using each algorithm. Predicted s-parameters for the optimized equivalent circuit are then obtained from HSPICE. The difference between the measured and predicted s-parameters in the frequency range of interest is used as a measure of the accuracy of the two optimization algorithms. It is determined that the LM method is extremely dependent upon the initial starting point of the parameter search and is thus prone to become trapped in local minima. This drawback is alleviated and the accuracy of the parameter values obtained is improved using genetic algorithms.
Gender and telomere length: Systematic review and meta-analysis
the Halcyon study team,Gardner, M.,Bann, D.,Wiley, L.,Cooper, R.,Hardy, R.,Nitsch, D.,Martin-Ruiz, C.,Shiels, P.,Sayer, A.A.,Barbieri, M.,Bekaert, S.,Bischoff, C.,Brooks-Wilson, A.,Chen, W.,Cooper, C. Pergamon Press ; Elsevier Science Ltd 2014 Experimental Gerontology Vol.51 No.-
Background: It is widely believed that females have longer telomeres than males, although results from studies have been contradictory. Methods: We carried out a systematic review and meta-analyses to test the hypothesis that in humans, females have longer telomeres than males and that this association becomes stronger with increasing age. Searches were conducted in EMBASE and MEDLINE (by November 2009) and additional datasets were obtained from study investigators. Eligible observational studies measured telomeres for both females and males of any age, had a minimum sample size of 100 and included participants not part of a diseased group. We calculated summary estimates using random-effects meta-analyses. Heterogeneity between studies was investigated using sub-group analysis and meta-regression. Results: Meta-analyses from 36 cohorts (36,230 participants) showed that on average females had longer telomeres than males (standardised difference in telomere length between females and males 0.090, 95% CI 0.015, 0.166; age-adjusted). There was little evidence that these associations varied by age group (p=1.00) or cell type (p=0.29). However, the size of this difference did vary by measurement methods, with only Southern blot but neither real-time PCR nor Flow-FISH showing a significant difference. This difference was not associated with random measurement error. Conclusions: Telomere length is longer in females than males, although this difference was not universally found in studies that did not use Southern blot methods. Further research on explanations for the methodological differences is required.