Comparative Analysis of Acinetobacters: Three Genomes for Three Lifestyles

Acinetobacter baumannii is the source of numerous nosocomial infections in humans and therefore deserves close attention as multidrug or even pandrug resistant strains are increasingly being identified worldwide. Here we report the comparison of two newly sequenced genomes of A. baumannii. The human isolate A. baumannii AYE is multidrug resistant whereas strain SDF, which was isolated from body lice, is antibiotic susceptible. As reference for comparison in this analysis, the genome of the soil-living bacterium A. baylyi strain ADP1 was used. The most interesting dissimilarities we observed were that i) whereas strain AYE and A. baylyi genomes harbored very few Insertion Sequence elements which could promote expression of downstream genes, strain SDF sequence contains several hundred of them that have played a crucial role in its genome reduction (gene disruptions and simple DNA loss); ii) strain SDF has low catabolic capacities compared to strain AYE. Interestingly, the latter has even higher catabolic capacities than A. baylyi which has already been reported as a very nutritionally versatile organism. This metabolic performance could explain the persistence of A. baumannii nosocomial strains in environments where nutrients are scarce; iii) several processes known to play a key role during host infection (biofilm formation, iron uptake, quorum sensing, virulence factors) were either different or absent, the best example of which is iron uptake. Indeed, strain AYE and A. baylyi use siderophore-based systems to scavenge iron from the environment whereas strain SDF uses an alternate system similar to the Haem Acquisition System (HAS). Taken together, all these observations suggest that the genome contents of the 3 Acinetobacters compared are partly shaped by life in distinct ecological niches: human (and more largely hospital environment), louse, soil

Voltage regulating circuit

A voltage regulating circuit comprising a rectifier (2) for receiving an AC voltage (Vmains) and for generating a rectified AC voltage (vrec), and a capacitor (3) connected in parallel with said rectified AC voltage for providing a DC voltage (VDC) over a load (5), characterized by a unidirectional current switch (4) provided between the rectifier (2) and the capacitor (3), and a control block (6) arranged to activate the switch (4) at selected instances (7) during negative slopes of the rectified AC voltage (vrec) so that said DC voltage (VDC) does not exceed a predetermined voltage limit. By controlling the voltage provided by the rectified mains, the DC voltage can be regulated to any preset value (lower than the AC mains peak value). The inventive voltage stabilizer will guarantee a desired constant DC load voltage value for different mains peak input voltages and under wide range of load variations. Thereby a converter driven by this voltage can be more optimized or even be unregulated

Isolated converter with synchronized switching leg

An amplification device is disclosed providing a way of integrating a switch mode power supply and a class D amplifier (switch mode amplifier). This results in the usage of basically one magnetic component (1), one major energy storage element (4) and switches (20, 30) that are controlled in such a way that both the power supply function and the amplification function are achieved. In this way a cheap, small and highly efficient current configuration is achieved. This amplification device is especially useful in audio product

A bidirectional power converter

A three-phase power converter for converting power between a power grid network and a battery (255) comprises a three-phase grid transformer (230), a three-phase switching converter (251) for coupling to a positive terminal of the battery, a first, second and third series inductors(Ls1, Ls2, Ls3) coupled between the three-phase grid transformer and the three-phase switching converter, a control circuit (262) configured for controlling a first, second and third phase differences between first, second and third time-periodical power grid voltage signals(Vs1, Vs, Vs3) provided by the grid transformer and first, second and third converter time-periodical voltage signals (Vc1, Vc2, Vc3)provided to the switching converter such that the first, second and third time- periodical power grid voltage signals(Vs1, Vs2, Vs3) and first, second and third converter time-periodical currents(Ic1, Ic2, Ic3) are in phase. The three-phase grid transformer provides electrical isolation between the power grid network and the batter