A 2-18 GHz low-noise/high-gain amplifier module

The effectiveness of the two-tier matrix amplifier as a very-low-noise device with very high associated gains across multioctave frequency bands is theoretically and experimentally demonstrated. Experimental modules whose topology is based on a computer-optimized design exhibit an average noise figure of F=3.5 dB with an associated average gain of G=17.8 dB across the 2-18 GHz frequency band. These state-of-the-art results were achieved with GaAs MESFETs whose minimum noise figure is F=2.2 dB at 18 GHz and whose gate dimensions are 0.25×200 μm. The design considerations and the test results are discussed in detail     

Real-time visualisation of fibre networks

Published online: 24 January 2002     

Application of multivariate analysis for software fault prediction

Prediction of fault-prone modules provides one way to support software quality engineering through improved scheduling and project control. The primary goal of our research was to develop and refine techniques for early prediction of fault-prone modules. The objective of this paper is to review and improve an approach previously examined in the literature for building prediction models, i.e. principal component analysis (PCA) and discriminant analysis (DA). We present findings of an empirical study at Ericsson Telecom AB for which the previous approach was found inadequate for predicting the most fault-prone modules using software design metrics. Instead of dividing modules into fault-prone and not-fault-prone, modules are categorized into several groups according to the ordered number of faults. It is shown that the first discriminant coordinates (DC) statistically increase with the ordering of modules, thus improving prediction and prioritization efforts. The authors also experienced problems with the smoothing parameter as used previously for DA. To correct this problem and further improve predictability, separate estimation of the smoothing parameter is shown to be required.     

面向回收利用和面向维护设计中的辅助手段

 考虑到合法的规程和竞争差异，可回收利用的产品对于资本货物(生产资料)工业的意义也在增长．但迄今为止设计辅助手段的缺乏阻碍了这种特定需求有目的地实现． 在考虑协同工作的情况下，将面向回收利用和面向维护的设计结合在一起，并基于方法学进程方式提出了具体的辅助手段供工业实践应用．     

Low-noise amplification of voltage and current fluctuations arising in epithelia

Two low-noise differential input amplifiers designed for voltage and current fluctuation measurements in epithelia are described. The first one uses a matched pair of low-noise transistors and is particularly suited for low-frequency current and voltage noise measurements in frog skin and other preparations with impedances below 1 kOmega. The second one is designed around a matched pair of JFETs and can also be used for higher source impedance. Performance is demonstrated with Na(+) current power density spectra obtained from frog skin with the transistor-input stage.     

Graphitized carbon LC-MS characterization of the chondroitin sulfate oligosaccharides of aggrecan

A novel in-gel endoglycosidase technique to study oligosaccharides with graphitized carbon LC-MS has revealed differences in the sulfation profile between the linkage and repeat regions of chondroitin sulfate on aggrecan. Bovine articular cartilage aggrecan was isolated in a composite agarose PAGE gel or diluted in ammonium acetate buffer and was digested overnight with chondroitinase ABC. Including a chemical release/reduction protocol after digestion, we could separate and detect three differentially sulfated chondroitin sulfate disaccharides of the repeat region (DeltaUA1-3GalNAc0/4/6S-ol) from the three differentially sulfated linkage region hexasaccharides (DeltaUA1-3GalNAc0/4/6Sbeta1-4GlcAbeta1-3Galbeta1-3Galbeta1-4Xylitol). Graphitized carbon LC-MS in the negative ion mode was able to resolve isomeric disaccharides and linkage region hexasaccharides. Specific MS2 and MS3 enabled us to confirm the sulfate location on all oligosaccharides by comparing their fragmentation with sulfated disaccharide standards. The presence of unsulfated, 6-sulfated, and 4-sulfated linkage regions was correlated with positive Western blot staining with the respective CS linkage region neoepitope antibodies (1B5, 3B3, 2B6) on digested aggrecan. Our strategy of examining linkage region and repeat region profiles is applicable to screening GAGs from various biological samples in order to detect differences between normal and disease states.