Demonstration of wide band RF photonic transversal phase-shifter

A transversal phase-shifter using multiple MZMs is demonstrated. The device exhibits continuously variable phase-shift exceeding 360° at 2 GHz and amplitude uniformity within 3 dB over 0.2-2 GHz. The device stability and practicality are discussed

Wide-band variable transversal phase-shifter

We present a novel broadband phase-shifter based on a transversal filter configuration. This approach allows flexible control of the amplitude response while providing continuous variation of a linear phase slope. Numerical examples, both ideal and using practical RF components are presented and practical challenges in realising the phase-shifter are identified

Wideband RF photonic vector sum phase-shifter

A novel broadband linear phase phase-shifter based on the vector summation method is proposed. A photonic implementation of the phase-shifter with a continuously variable linear phase-shift up to 120° over the frequency range of DC-4 GHz is demonstrated. Good agreement between the measured responses and theoretical predictions is obtained

ALS in Italian professional soccer players: the risk is still present and could be soccer-specific

We previously found an increased risk for ALS in Italian professional soccer players actively engaged between 1970 and 2001 (n=7325). The present study extends previous work with a prospective follow-up of the original cohort to 2006 and investigates the risk of ALS in two other cohorts of professional athletes, basketball players (n=1973) and road cyclists (n=1701). Standardized morbidity ratios (SMRs) were calculated. Among soccer players three new cases of ALS were identified, reaching a total of eight ALS cases (mean age of onset, 41.6 years). The number of expected cases was 1.24, with an SMR of 6.45 (95% CI 2.78-12.70; p5 years, for midfielders, and for players engaged after 1980. No basketball player and no cyclist developed ALS. This prospective extension of the Italian soccer players cohort survey confirms the highly significant risk of developing ALS, the young age of onset, the dose-effect risk and a predilection for midfielders. The absence of ALS cases in professional road cyclists and basketball players indicates that ALS is not related to physical activity per s

Structural Adaptability Facilitates Histidine Heme Ligation in a Cytochrome P450

Almost all known members of the cytochrome P450 (CYP) superfamily conserve a key cysteine residue that coordinates the heme iron. Although mutation of this residue abolishes monooxygenase activity, recent work has shown that mutation to either serine or histidine unlocks non-natural carbene- and nitrene-transfer activities. Here we present the first crystal structure of a histidine-ligated P450. The T213A/C317H variant of the thermostable CYP119 from Sulfolobus acidocaldarius maintains heme iron coordination through the introduced ligand, an interaction that is accompanied by large changes in the overall protein structure. We also find that the axial cysteine C317 may be substituted with any other amino acid without abrogating folding and heme cofactor incorporation. Several of the axial mutants display unusual spectral features, suggesting that they have active sites with unique steric and electronic properties. These novel, highly stable enzyme active sites will be fruitful starting points for investigations of non-natural P450 catalysis and mechanisms