To investigate the possibility that the unusual dominant rifampicin-resistance characteristic of the rifd18 allele of E. coli rpoB is due to a secondary, regulatory mutation, we have determined the nucleotide sequence of a 1.1 Kbp wild-type DNA fragment, including the transcriptional attenuator and translational start-site of rpoB. We have also re-investigated the previously published sequences...

The ilvGMEDA operon of Escherichia coli K-12 is preceded by a regulatory region containing a promoter, a leader, and an attenuator. This region has been extensively characterized biochemically. In this note point mutations of the regulatory region are reported. The effect of these mutations on expression from the ilv regulatory region supports the previous biochemical analysis.

Overproduction of tryptophanyl-tRNA synthetase increased trp operon expression by reducing transcription termination at the trp attenuator. The total cellular level of charged tRNATrp was not affected by increased levels of the synthetase. We propose that excess synthetase binds charged tRNATrp and reduces the concentration available for translation.

The paper addresses on-chip test for IC RF transceivers. The baseband DSP available on chip serves as a tester while the RF front-end is reconfigured for test. The basic test setup is a loopback, enabled by a test attenuator and in some cases by an offset mixer, too. Different variants of this setup adopt the bypassing technique to boost testability. The existing limitations and tradeoffs in te...

Figure 1 is a general block diagram for an AGC loop. The input signal passes through the VGA to produce a signal output whose level will be stabilized. The output level is measured by a detector, whose output is compared against a setpoint voltage to produce an error signal. The error signal is then integrated to produce a gain control voltage that is applied to the control input of the VGA. It...

This paper investigates four receiver architectures and their ability to track the carrier phase signal under attenuated environments. The receiver architectures considered include a standard receiver, an estimator-based receiver, a vector-based receiver and an ultra-tight GPS/IMU receiver. The receiver architectures were implemented in software and tested using pedestrianbased data collected i...

The Novac7 and Liac are linear accelerators (linacs) dedicated to intraoperative radiation therapy (IORT), which produce high energy, very high dose-per-pulse electron beams. The characteristics of the accelerators heads of the Novac7 and Liac are different compared to conventional electron accelerators. The aim of this work was to investigate the specific characteristics of the Novac7 and Liac...

Under the condition of first-order blooming, a parallel dielectric slab, which is inserted in the path of an obliquely incident p- or s-polarized light beam, introduces multiple discrete attenuation levels given by 1/3, 4/27, 4/243,...... in reflection and 4/9, 4/81, 4/729,...... in transmission. These attenuation levels are independent of the slab refractive index, incident p or s linear polar...