Comparative analysis of long-haul system based on SSB modulation utilising dual parallel Mach–Zehnder modulators

In this paper, we have proposed a long-haul optical transmission system, based on a single sideband (SSB) modulation scheme. Analytical and simulation models have been developed, optimised and demonstrated for the proposed SSB system configurations. The SSB modulation scheme was proposed to overcome dispersion in the fibre. We have shown that the related link losses can be minimized by increasing the quality of the optical signal at the modulation. We have optimised the radio over fibre configuration scheme based on dual parallel dual drive Mach–Zehnder Modulator, thereby increasing transmission length of the fibre. With the proposed SSB, by suppressing some of the harmonics and cancelling one of the sidebands, we have halved the RF power fading and interference. The developed analytical (theoretical/mathematical) model agrees very well with the simulation results using two (both) different commercial simulation tools. The optical signal is boosted while minimizing the number of repeaters. We report a SSB configuration, compensation and amplification with individual spans of 150 km, by extending the length of the link up to 3250 km. The proposed system configuration exhibits high performance with less complexity and lower cost

TRAP binding to the Bacillus subtilis trp leader region RNA causes efficient transcription termination at a weak intrinsic terminator

The Bacillus subtilis trpEDCFBA operon is regulated by a transcription attenuation mechanism controlled by the trp RNA-binding attenuation protein (TRAP). TRAP binds to 11 (G/U)AG repeats in the trp leader transcript and prevents formation of an antiterminator, which allows formation of an intrinsic terminator (attenuator). Previously, formation of the attenuator RNA structure was believed to be solely responsible for signaling RNA polymerase (RNAP) to halt transcription. However, base substitutions that prevent formation of the antiterminator, and thus allow the attenuator structure to form constitutively, do not result in efficient transcription termination. The observation that the attenuator requires the presence of TRAP bound to the nascent RNA to cause efficient transcription termination suggests TRAP has an additional role in causing termination at the attenuator. We show that the trp attenuator is a weak intrinsic terminator due to low GC content of the hairpin stem and interruptions in the U-stretch following the hairpin. We also provide evidence that termination at the trp attenuator requires forward translocation of RNA polymerase and that TRAP binding to the nascent transcript can induce this activity

Fractional Integration Versus Structural Change: Testing the Convergence of CO2 Emissions

This paper assesses the stochastic convergence of relative CO₂ emissions within 28 OECD countries over the period 1950–2013. Using the local Whittle estimator and some of its variants we assess whether relative per capita CO₂ emissions are long memory processes which, although highly persistent, may revert to their mean/trend in the long run thereby indicating evidence of stochastic convergence. Furthermore, we test whether (possibly) slow convergence or the complete lack of it may be the result of structural changes to the deterministics of each of the relative per-capita emissions series by means of the tests of Berkes et al. (Ann Stat 1140–1165, 2006) and Mayoral (Oxford Bull Econ Stat 74(2):278–305, 2012). Our results show relatively weak support for stochastic convergence of CO₂ emissions, indicating that only between 30 and 40% of the countries converge to the OECD average in a stochastic sense. This weak evidence disappears if we enlarge the sample to include 4 out of the 5 BRICS, indicating that our results are not robust to the inclusion of countries which are experiencing rates of growth which are far larger than those of the OECD members. Our results also decisively indicate that a slow or lack of convergence is not the results of a structural break in the relative CO₂ emissions series

Interview with Harry Shimotsu, 1979

Rio Grande Valley Interviewed in his truck while near border with Mexico in Rio Grande Valley, Harry Shimotsu discusses farming operations and history of his family, including cooperative farming venture for the Japanese community after WWII

Exact local Whittle estimation of fractionally integrated processes

Period of award: May 2001 - Aug 2002. Includes bibliographical referencesAvailable from British Library Document Supply Centre- DSC:3739. 0605(000223629) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo