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This paper present and discuss two methods that allows defining MTL models that allows to represent the railway power electrification systems with a reduced number of conductors. Groups of conductors shorted together are replaced with an equivalent conductor and group of conductors grounded are included into the reference conductor. Reducing criteria are developed in the frequency domain and their extension to the time domain is discussed. A section of the Italian 2x25 kV 50 Hz AC high speed railway power system is considered as a benchmark and reduction methods are applied to the MTL cells that represent this kind of electrification system, also including the high voltage grid that supply the Electrical Substation. The equivalent impedance at pantograph terminals and the disturbances on the track circuits caused by trains harmonic current injection are evaluated by using reduced models and taking into account several train positions along the railway line. The numerical results are reported, compared and discussed, considering both precision and computational times. [ABSTRACT FROM AUTHOR]

In recent years, literature has presented an increasing number of contributions showing a rising interest in four-phase symmetric networks with reference to power electrical systems and electromechanic conversion and drivers. In this paper, a complete methodological analysis of four-phase systems, based on the phasorial and instantaneous sequence components, is presented for sinusoidal and dynamic conditions. This approach allows for the formalization of the theoretical and applicative methodologies necessary for the development of four-phase systems in a systematic and unified way. [ABSTRACT FROM AUTHOR]

Six healthy, fasting volunteers were given single doses of chlordesmethyldiazepam by 1 mg i. v., or as drops or tablets. Chlordesmethyldiazepam and its metabolite, lorazepam, in multiple plasma samples and in urine collected for 120 h after each dose were determined by electron-capture GLC. Mean kinetic variables for intravenous chlordesmethyldiazepam were: volume of distribution, 1.71 l · kg; elimination half-life, 113 h; total clearance, 0.21 ml · min · kg; cumulative excretion of lorazepam glucuronide 24.2% of the dose. Following a lag time of 15.5 min (tablets) and 4.2 min (drops), which were significantly different, the absorption of oral chlordesmethyldiazepam was a first order process, with apparent absorption half-life values averaging 1.5 h (tablets) and 1.1 h (drops). Bioavailability was 77% for tablets and 79% for drops. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on safety and efficacy of duodenal levodopa-carbidopa infusion in six patients affected by Parkinson's diseases (PD) that was published in the December 2008 issue.