Spectral purity and tunability of terahertz quantum cascade laser sources based on intracavity difference-frequency generation.

Terahertz sources based on intracavity difference-frequency generation in mid-infrared quantum cascade lasers (THz DFG-QCLs) have recently emerged as the first monolithic electrically pumped semiconductor sources capable of operating at room temperature across the 1- to 6-THz range. Despite tremendous progress in power output, which now exceeds 1 mW in pulsed and 10 µW in continuous-wave regimes at room temperature, knowledge of the major figure of merits of these devices for high-precision spectroscopy, such as spectral purity and absolute frequency tunability, is still lacking. By exploiting a metrological grade system comprising a terahertz frequency comb synthesizer, we measure, for the first time, the free-running emission linewidth (LW), the tuning characteristics, and the absolute center frequency of individual emission lines of these sources with an uncertainty of 4 × 10-10. The unveiled emission LW (400 kHz at 1-ms integration time) indicates that DFG-QCLs are well suited to operate as local oscillators and to be used for a variety of metrological, spectroscopic, communication, and imaging applications that require narrow-LW THz sources.

[Evaluation of a rapid diagnostic test for influenza viruses A and B]. / Valutazione di un test rapido per la diagnosi dei virus influenzali A e B.

This study analysed the performance of a rapid test for the diagnosis of human influenza A and B. Three-hundred nasopharyngeal samples were analysed using the BD Directigen Flu A+B test and real-time PCR, during the 2007-2008 and 2008-2009 flu seasons. Specificity of the BD Directigen Flu A+B test was 100% and sensitivity was fpund to be 67% for influenza B virus and 89% for the detection of influenza B virus. Results are comparable to those reported in the literature and by the Centers for Disease Control (CDC).

Ten-year (1999-2009) epidemiological and virological surveillance of influenza in South Italy (Apulia).

Clinical and epidemiological surveillance of influenza and other Acute Respiratory Infections (ARI) are currently a major objective of Public Health. The aim was to describe the epidemiology of influenza using the Italian surveillance system. Vaccination Coverage (VC) rates were calculated during 1999-2009 influenza seasons. Molecular studies of influenza virus isolated, from patients with ILI, living in Apulia, are described. 1269 nasal-pharyngeal swabs were taken from patients with ILI and ARI in order to isolate and identify viruses using PCR. Influenza isolates are typed as being types A and B and influenza A isolates are A/H1 and A/H3. The progression of the ILI cases registered in Apulia was similar to the data recorded on a national level. The VC data recorded in Apulia showed a progressive increase in the vaccine doses administered to subjects over 65 years old. The virological surveillance showed a major circulation of the type A/H3N2 influenza virus during the peak incidence of the illness in seasons 1999-2000, 2002-2003, 2004-2005 and 2008-2009. During the same period, the lowest incidence was registered when the type A/H1N1 and B viruses were in circulation. In contrast, during the other seasons the lowest incidence was reported with A/H3N2 and B viruses.

[Evaluation of hydrocarbon-oxidizing bacteria in port water and of health risks related to harbour activities: port of Otranto (Italy)]. / Stato di salute del porto di Otranto: batteri idrocarburo ossidanti e valutazione del rischio igienico-sanitario connesso alle attività portuali.

The aim of this study was to evaluate the water quality of the port of Otranto (Italy), through a combined approach which integrates monitoring of traditional microbiological parameters and studying the dynamics of some autochthonous bacterial communities. The fecal contamination indicators, total coliforms, fecal coliforms, and fecal streptococci were measured to evaluate the sanitary aspects, while the presence of organic matter was considered as a parameter strictly related to dumping. In addition, being the port of Otranto especially exposed to hydrocarbon pollution, hydrocarbon-oxidizing bacteria were evaluated. Fecal contamination indicators were consistently found to be below the threshold values set by the Italian legislative decree N. 470/82 for bathing waters, indicating a good microbiological quality of these waters. A higher density of hydrocarbon-oxidizing bacteria was found at mooring and craft transit areas. This parameter was therefore found to be useful for evaluating port water hydrocarbon pollution.