Design and Experimental Characterization of EDFA Based WDM Ring Networks with Free ASE Light Re-circulation and Link Control for Network Survivability

In this paper, we theoretically and experimentally investigate the performance of erbium-doped fiber amplifier (EDFA)-based WDM ring networks with free amplified spontaneous emission (ASE) light recirculation. We show that, with proper network and amplifier design, the lasing light generated by free ASE recirculation within the looped network provides an effective gain clamping technique, ensuring limited signal power excursions under WDM channels add-drop operations. Considering a ring network composed of eight fiber sections and eight EDFAs, maximum signal power overshoots below 2.5 dB have been measured under 23 24 WDM channels drop. Optical signal-to-noise ratio (OSNR) analysis and bit-error rate (BER) measurement at 10 Gb/s confirm acceptable performances and negligible penalties due to polarization effects and relative intensity noise transfer from laser light to WDM signals. We also propose and demonstrate a new link control technique which overcomes the main limiting factors of such networks, respectively, related to OSNR degradation, stability and survivability to fiber and EDFA breakages

Alternative Splicing of Circadian Clock Genes Correlates With Temperature in Field-Grown Sugarcane

Alternative Splicing (AS) is a mechanism that generates different mature transcripts from precursor mRNAs (pre-mRNAs) of the same gene. In plants, a wide range of physiological and metabolic events are related to AS, as well as fast responses to changes in temperature. AS is present in around 60% of intron-containing genes in Arabidopsis, 46% in rice, and 38% in maize and it is widespread among the circadian clock genes. Little is known about how AS influences the circadian clock of C4 plants, like commercial sugarcane, a C4 crop with a complex hybrid genome. This work aims to test if the daily dynamics of AS forms of circadian clock genes are regulated by environmental factors, such as temperature, in the field. A systematic search for AS in five sugarcane clock genes, ScLHY, ScPRR37, ScPRR73, ScPRR95, and ScTOC1 using different organs of sugarcane sampled during winter, with 4 months old plants, and during summer, with 9 months old plants, revealed temperature- and organ-dependent expression of at least one alternatively spliced isoform in all genes. Expression of AS isoforms varied according to the season. Our results suggest that AS events in circadian clock genes are correlated with temperature.</p

An analysis of seed longevity in Arabidopsis using modifiers of seed maturation mutants

Seeds ensure the survival of most land plant species and the conservation of their unique genetic resources. Seed longevity is a quantitative trait that depends on environmental conditions during formation, harvest and storage of seeds and on structures, macromolecules and chemical compounds that protect the embryo. Seed longevity is consequently a complex genetic trait to dissect. Its study requires the identification of factors that result in an improvement or in a reduction of seed longevity. Wild-type seeds of the model plant Arabidopsis remain viable for several years, which makes the study of longevity a time consuming process. An approach to overcome this problem makes use of the seed developmental mutants abi3-5 and lec1-3, that cause rapid seed deterioration. These mutants provide a sensitized genetic background in which the effects of genes influencing longevity can be faster evaluated. The Arabidopsis natural variation for longevity was exploited by crossing several Arabidopsis accessions with abi3-5 and lec1-3 mutants and subsequent selection of lines with improved longevity in the progeny. As a result, various introgression lines carrying natural modifiers alleles were identified. The three natural modifier lines with the strongest effects were selected. One had an introgression of the Seis am Schlern accession in abi3-5 background and two had different introgressions of the Shahdara accession in lec1-3 background. These lines were backcrossed with abi3-5 or lec1-3 to reduce the contribution of wild-type accession�s genome and to map the modifiers. The seed proteome profiles of modifier and mutant lines were studied in relation to longevity. This analysis revealed that the two modifiers from Shahdara could activate the expression of most seed storage proteins in a LEC1-independent way. In addition, four abi3-5 suppressor mutants derived from a mutagenesis screen were studied. In these lines the level of oxidative damage was correlated with seed longevity. The strongest suppressor, suppressor of abi3-5 (sua), reverted all of the abi3-5 mutant phenotypes. Fine mapping and map based cloning revealed that SUA encodes an RNA binding protein. Interestingly, sua only suppressed the abi3-5 allele but did not affect other abi3 alleles. Immunological analysis revealed that abi3-5 seeds contain a truncated abi3 protein which is restored to nearly full length ABI3 protein in the sua abi3-5 double mutant. Analysis of transcripts revealed that the sua mutation causes the splicing of a cryptic intron in ABI3 and the accumulation of a splice variant that repairs the abi3-5 mutation and results in a shorter but functional version of the ABI3 protein. The SUA gene is not directly implicated in seed longevity, but participates in mRNA metabolism processes

Iron Based Nano-hydrotalcites Promoted with Cu as Catalysts for Fischer-tropsch Synthesis in Biomass to Liquid Process

Two different groups of MgCuFe catalysts derived from hydrotalcite-like precursors were prepared through ultrasound-assisted (US) co-precipitation and solvent-free ball milling methods (BM). The catalysts were activated at 623°K, 1.5 MPa for 4 h in syngas, and their performances in the production of fuels through Fischer–Tropsch (FT) synthesis were evaluated in a fixed bed reactor at temperatures ranging from 473° to 573°K and 2 MPa and H2/CO molar ratio of 2. The physicochemical properties of the fresh and spent catalysts were investigated and characterized using different methods, including XRPD, ICP-OES, SEM, and TEM. Catalysts displayed similar catalytic activity for both BM and US with minor differences when operating at temperatures from 473° to 523°K. The results hint at the possibility of using synthetic hydrotalcites as Fe-based catalysts for the Fischer–Tropsch synthesi

Double Rayleigh Scattering Noise in Raman Amplifiers Using Pump Time-Division-Multiplexing Schemes

The impact of signal double Rayleigh scattering (DRS) noise in time-division multiplexed counterpropagating Raman pumping schemes is theoretically and experimentally investigated. We show that, for small pump modulation duty cycles, DRS noise can be greatly enhanced with respect to continuous-wave pumping. By increasing the pump modulation frequency, however, this detrimental effect is effectively reduced, providing a powerful technique for noise figure equalization and pump four-wave mixing suppression in large bandwidth discrete and distributed amplifier