In-Field n × 40 Gb/s Transmission Experiments with In-Line All-Optical Wavelength Conversion

In this work, WDM transmission with 40-Gbit/s per channel bit rate has been experimentally demonstrated over a 500-km link. Different chromatic dispersion conditions have been managed and in-line all-optical wavelength conversion has been carried out with a periodical poled lithium niobate (PPLN) device in a polarization-independent scheme. The link was obtained by connecting the fibers contained in an installed cable between Roma and Pomezia (25 km), encompassing single-mode (G.652) and high-end (G.655, non-zero dispersion with a particular value and flat curve for chromatic dispersion) fibers. Some 40 Gb/s channels were propagated in the link 500 km long and one channel was dropped from the link after 300-km propagation, wavelength converted, and added to the other channels for the next 200 km. The electrical data interfaces exploited a 4 × 10 Gbit/s to 1 × 40 Gbit/s MUX at the transmitter, along with a 1 × 40 Gbit/s to 4 × 10 Gbit/s DMUX at the receiver. Successful transmission of 4 channels, 200-GHz spaced, has been achieved over 500 km along both G.652 and G.655 links. No evidence of penalty comparing converted and unconverted channels has been reported. Transmission experiments of 8 × 40 Gbit/s, with 100 GHz frequency spacing, are also reported. No significant degradation has been observed in the case of the G.652 link.     

Nonequilibrium quantum dynamics of a charge carrier doped into a Mott insulator

We study real-time dynamics of a charge carrier introduced into an undoped Mott insulator propagating under a constant electric field F on the t-J ladder and a square lattice. We calculate the quasistationary current. In both systems an adiabatic regime is observed followed by a positive differential resistivity (PDR) at moderate fields where the carrier mobility is determined. Quantitative differences between the ladder and two-dimensional (2D) systems emerge when at large fields both systems enter the negative differential resistivity (NDR) regime. In the ladder system Bloch-like oscillations prevail, while in two dimensions the current remains finite, proportional to 1/F. The crossover between the PDR and NDR in two dimensions is accompanied by a change of the spatial structure of the propagating spin polaron.     

Automated statistical control of activities measured by gamma-ray spectrometry

Statistical tests were performed for reviewing the results of routinely performed measurements. Within the operating procedure for routine spectral analysis the current results were compared with the average values obtained from measurements of samples of the same type collected at the same location. The agreement of the current result with the population of the results was assessed by the u-statistic, where the expected spread of the population of the results is given by their standard deviation and their uncertainties. After checking for reliability, the current result was used for updating the average and the spread of the population. Some examples are presented to illustrate how the average and the spread follow changes in the population of the measurement results.     

Visualising concordance

Concordance describes the agreement between m rankings of k objects. Despite the long history of measures of concordance and the recently revived interest in comparison of concordance (c.f. Legendre in J Agric Biol Environ Stat 10(2):226–245, 2005), the task of visualising concordance remained virtually unaddressed. We first show how to depict concordance by simply plotting raw data in parallel coordinates. Then we review further possibilities for depicting concordance using the recently developed plots of inter-rater variability in ordinal ratings (Nelson and Pepe in Stat Methods Med Res 9:475–496, 2000) and plots of correlation matrices (Trosset in J Comput Graph Stat 14(1):1–19, 2005). Next, we propose two novel concordance plots. The concordance bubble-plot is based on raw rank data, while the pin-cushion plot depicts rank differences in polar coordinates. We present visualisations of artificial and real-life datasets with different degree of concordance and identify strong and weak points of the proposed plots. In conclusion, we review some other work related to visualisation of concordance and discuss some other options for constructing novel concordance plots.     

On the use of atmospheric pressure plasmas as electromagneticreflectors and absorbers

Tenuous man-made plasmas in the Earth's atmosphere from sea level to 100 km are discussed. An ionization source generates a tenuous plasma with an electron number density n_e that is high near the source and diminishes with distance from the source. After the source shuts off, n_e decreases as a function of time as electrons recombine with positive ions or attach to negative ions. The electromagnetic properties that are essential to an understanding of these plasmas, which can be modeled as cold collisional plasmas, is discussed. Gas and plasma characteristics, such as momentum-transfer collision rate, plasma lifetime, recombination kinetics, and the effect of noble gases, are presented. Typical collision rates and plasma lifetimes at atmospheric pressure are quantified. Applications for a plasma with a gradient are discussed. They include a high-altitude plasma that can reflect or absorb from HF to VHF and a broadband atmospheric pressure absorber. The generation and use of plasma, including electron impact ionization with a high-energy electron-beam source and UV photoionization of an alkali vapor or an organic vapor such as tetrakis (dimethylamino)ethylene (TMAE), is described. The power required to sustain a plasma is quantified, and properties such as maximum absorption and bandwidth are discussed. Tradeoffs among maximum absorption, absorption bandwidth, duty ratio, and applied power permit optimization of absorption primarily at VHF     

Sodium Chloride Aerosol Generation Method for high Efficiency Particulate air Filter Testing

A method for submicron aerosol generation from the sodium chloride aqueous solution and the results related to the generation capacity and aerosol particle characterization as a function of the experimental conditions are presented.