Signal regeneration techniques for advanced modulation formats

We review recent results on all-optical regeneration of phase encoded signals based on phase sensitive amplification achieved by avoiding phase-to-amplitude conversion in order to facilitate the regeneration of amplitude/phase encoded (QAM) signals

PSA-based all-optical multi-channel phase regenerator

We demonstrate simultaneous phase regeneration of six NRZ BPSK signals in a single nonlinear medium using FWM-based phase sensitive amplification. BER measurements confirm OSNR improvement and negligible cross-talk across all the regenerated channels, impaired with broadband phase noise

Phase Regeneration of QPSK Signal in SOA Using Single-Stage, Wavelength Converting PSA

We demonstrate, for the first time, all-optical phase regeneration of a quaternary phase shift keying (QPSK) signal through phase sensitive amplification (PSA) in nonlinear semiconductor optical amplifiers (SOAs), using a scheme only previously demonstrated in highly nonlinear fibre (HNLF). We make use of a highly tunable phase quantising scheme to circumvent some of the limitations imposed by the use of SOAs and show that it may function in either a conjugating or non-conjugating manner

Calculating the carbon footprint:implications for governing emissions and gender relations

In this article, we use fresh empirical evidence, and draw on feminist and critical accounting and organisational theories to contend that carbon calculators can be interpreted as discriminatory control technologies. They do this by providing a new and flexible vocabulary for governing expenses, costs and investments at a distance, avoiding a sense of direct intervention by the government. Thus, given our stance that the carbon calculator cannot be considered a neutral tool, we argue that it has the potential to control personal responsibilities regarding both environmental and family‐based issues

Protein kinase B controls Mycobacterium tuberculosis growth via phosphorylation of the transcriptional regulator Lsr2 at threonine 112.

Mycobacterium tuberculosis (Mtb) is able to persist in the body through months of multi-drug therapy. Mycobacteria possess a wide range of regulatory proteins, including the protein kinase B (PknB) which controls peptidoglycan biosynthesis during growth. Here, we observed that depletion of PknB resulted in specific transcriptional changes that are likely caused by reduced phosphorylation of the H-NS-like regulator Lsr2 at threonine 112. The activity of PknB towards this phosphosite was confirmed with purified proteins, and this site was required for adaptation of Mtb to hypoxic conditions, and growth on solid media. Like H-NS, Lsr2 binds DNA in sequence-dependent and non-specific modes. PknB phosphorylation of Lsr2 reduced DNA binding, measured by fluorescence anisotropy and electrophoretic mobility shift assays, and our NMR structure of phosphomimetic T112D Lsr2 suggests that this may be due to increased dynamics of the DNA-binding domain. Conversely, the phosphoablative T112A Lsr2 had increased binding to certain DNA sites in ChIP-sequencing, and Mtb containing this variant showed transcriptional changes that correspond with the change in DNA binding. In summary, PknB controls Mtb growth and adaptations to the changing host environment by phosphorylating the global transcriptional regulator Lsr2

Plasmodium NEK1 coordinates MTOC organisation and kinetochore attachment during rapid mitosis in male gamete formation

Mitosis is an important process in the cell cycle required for cells to divide. Never in mitosis (NIMA)-like kinases (NEKs) are regulators of mitotic functions in diverse organisms. Plasmodium spp., the causative agent of malaria is a divergent unicellular haploid eukaryote with some unusual features in terms of its mitotic and nuclear division cycle that presumably facilitate proliferation in varied environments. For example, during the sexual stage of male gametogenesis that occurs within the mosquito host, an atypical rapid closed endomitosis is observed. Three rounds of genome replication from 1N to 8N and successive cycles of multiple spindle formation and chromosome segregation occur within 8 min followed by karyokinesis to generate haploid gametes. Our previous Plasmodium berghei kinome screen identified 4 Nek genes, of which 2, NEK2 and NEK4, are required for meiosis. NEK1 is likely to be essential for mitosis in asexual blood stage schizogony in the vertebrate host, but its function during male gametogenesis is unknown. Here, we study NEK1 location and function, using live cell imaging, ultrastructure expansion microscopy (U-ExM), and electron microscopy, together with conditional gene knockdown and proteomic approaches. We report spatiotemporal NEK1 location in real-time, coordinated with microtubule organising centre (MTOC) dynamics during the unusual mitoses at various stages of the Plasmodium spp. life cycle. Knockdown studies reveal NEK1 to be an essential component of the MTOC in male cell differentiation, associated with rapid mitosis, spindle formation, and kinetochore attachment. These data suggest that P. berghei NEK1 kinase is an important component of MTOC organisation and essential regulator of chromosome segregation during male gamete formation

Advanced nonlinear signal processing in silicon-based waveguides

This talk presents recent progress in optical signal processing based on compact waveguides fabricated mainly using silicon germanium alloys. Applications include supercontinuum generation, wavelength conversion and signal regeneration

Biodegradable core crosslinked star polymer nanoparticles as 19F MRI contrast agents for selective imaging

With the aim of developing stimuli-responsive imaging agents, we report here the synthesis of core crosslinked star (CCS) polymers and their evaluation as pH-sensitive 19F magnetic resonance imaging (19F MRI) contrast agents. Block copolymers consisting of poly(ethylene glycol)methyl ether methacrylate (PPEGMA) as the first block and a copolymer of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and 2,2,2-trifluoroethyl methacrylate (TFEMA) as the second block were synthesised using RAFT polymerisation. The polymerisation kinetics were studied in detail. The block copolymers were then used as arm precursors for the arm-first synthesis of CCS polymers through RAFT dispersion polymerisation. The synthetic conditions were investigated and optimised. CCS polymers with a degradable core were also synthesised and evaluated as 19F MRI contrast agents. The degradation of the core was confirmed by treatment with various reducing agents. The particle size, 19F NMR signal and relaxation times as well as 19F MRI imaging performance of the CCS polymers were studied at a range of value of solution pH. Significant enhancement of the image intensity was observed when the pH was decreased from 8 to 5, indicating that the CCS nanoparticles could be used as 19F MRI contrast agents for the detection of the acidic environment within tumour tissue

Investing in Threatened Species Conservation: Does Corruption Outweigh Purchasing Power?

In many sectors, freedom in capital flow has allowed optimization of investment returns through choosing sites that provide the best value for money. These returns, however, can be compromised in countries where corruption is prevalent. We assessed where the best value for money might be obtained for investment in threatened species that occur at a single site, when taking into account corruption. We found that the influence of corruption on potential investment decisions was outweighed by the likely value for money in terms of pricing parity. Nevertheless global conservation is likely to get best returns in terms of threatened species security by investing in “honest” countries than in corrupt ones, particularly those with a high cost of living