EXPLORING THE SAMPLING RATE REQUIREMENTS FOR BEHAVIOURAL AMPLIFIER

Abstract: In this paper it is shown that for the purpose of nonlinear power amplifier behavioural modelling, the sampling rate can be set to the Nyquist rate of the input signal, rather than to the Nyquist rate of the output signal by making use of Zhu’s generalized sampling theorem. This claim is supported by measurements on a basestation power amplifier. The findings are that the model error obtained when the output signal is sampled at the Nyquist rate of the input signal is approximately 1.5 dB higher than when the sampling rate is set to the Nyquist rate of the output signal. However, if a sampling rate of twice the Nyquist rate of the input signal is used, which is still typically, much lower than the Nyquist rate of the output signal, the degradation is only 0.2 dB. These are important findings that will substantially ease the requirements on ADCs used in measurement setups used for amplifier modelling

High-Resolution Melting-Curve Analysis of Ligation-Mediated Real-Time PCR for Rapid Evaluation of an Epidemiological Outbreak of Extended-Spectrum-Beta-Lactamase-Producing Escherichia coli ▿

Methods for the confirmation of nosocomial outbreaks of bacterial pathogens are complex, expensive, and time-consuming. Recently, a method based on ligation-mediated PCR (LM/PCR) using a low denaturation temperature which produces specific melting-profile patterns of DNA products has been described. Our objective was to further develop this method for real-time PCR and high-resolution melting analysis (HRM) in a single-tube system optimized in order to achieve results within 1 day. Following the optimization of LM/PCR for real-time PCR and HRM (LM/HRM), the method was applied for a nosocomial outbreak of extended-spectrum-beta-lactamase (ESBL)-producing and ST131-associated Escherichia coli isolates (n = 15) and control isolates (n = 29), including four previous clusters. The results from LM/HRM were compared to results from pulsed-field gel electrophoresis (PFGE), which served as the gold standard. All isolates from the nosocomial outbreak clustered by LM/HRM, which was confirmed by gel electrophoresis of the LM/PCR products and PFGE. Control isolates that clustered by LM/PCR (n = 4) but not by PFGE were resolved by confirmatory gel electrophoresis. We conclude that LM/HRM is a rapid method for the detection of nosocomial outbreaks of bacterial infections caused by ESBL-producing E. coli strains. It allows the analysis of isolates in a single-tube system within a day, and the discriminatory power is comparable to that of PFGE