Abstract
A new 1.3 GHz solid-state high-power RF amplifier (SSA) has been built for the Lighthouse project in close cooperation between Cryoelectra and RI Research Instruments. The amplifier was ...developed by Cryoelectra as a scalable compact system with an RF-power density of 40kW/m
2
. Its industrial design is very reliable and easy to maintain. The SSA delivers a continuous RF output power of more than 130 kW with a wall-plug efficiency of 63% and with very low phase noise. The power is generated by 40 patented RF amplifier modules each containing 8 GaN transistor units. Their outputs are combined by a coaxial 8-way combiner in the center of the module. Each module is connected to the 4x9-way cable-free waveguide combiner network and can be exchanged in the event of fault within minutes thanks to quick connectors. A sophisticated control system continuously monitors the state of all components for reliable machine and personnel protection.
Despite all the challenges encountered during development and production, the SSA was built and handed over to the client in the shortest possible time. It passed the acceptance test on site exceptionally well.
Abstract
Worldwide there is a push for producing medical isotopes using particle accelerators rather than fission reactors. Here we report on the operation of the beam test facility (BTF), set up and ...operated at the RI site in Bergisch Gladbach, Germany, comprising a dc-photogun designed for producing
99
Mo in the Lighthouse facility and commissioned by the Institute for Radio Elements (IRE, Belgium) 1. The gun is based on the successful CBETA design by the Cornell University3. The existing design has been reworked and integrated with a fully automatable photocathode production facility (PPF) designed for series production and exchange of photocathodes (PC).
This paper presents some aspects of a cost-effective design of a Doppler weather radar (DWR) transmitter pulsed power supplies incorporating state-of-the-art technologies. Special emphasis was given ...to the control system and to the performance of the solid-state power modulator. The new transmitter was compared to a traditional design by a theoretical analysis of the improvement factor limitations of both systems. Because it is difficult to find published papers which describe the application of the well-known MTI improvement factor derivation procedure on a real-word system, the authors have described this method to a greater extent.
Abstract
While the major virulence factors for
Vibrio cholerae
, the cause of the devastating diarrheal disease cholera, have been extensively studied, the initial intestinal colonization of the ...bacterium is not well understood because non-human adult animals are refractory to its colonization. Recent studies suggest the involvement of an interbacterial killing device known as the type VI secretion system (T6SS). Here, we tested the T6SS-dependent interaction of
V. cholerae
with a selection of human gut commensal isolates. We show that the pathogen efficiently depleted representative genera of the Proteobacteria in vitro, while members of the
Enterobacter cloacae
complex and several
Klebsiella
species remained unaffected. We demonstrate that this resistance against T6SS assaults was mediated by the production of superior T6SS machinery or a barrier exerted by group I capsules. Collectively, our data provide new insights into immunity protein-independent T6SS resistance employed by the human microbiota and colonization resistance in general.
Chitin Induces Natural Competence in Vibrio cholerae Meibom, Karin L.; Blokesch, Melanie; Dolganov, Nadia A. ...
Science (American Association for the Advancement of Science),
12/2005, Letnik:
310, Številka:
5755
Journal Article
Recenzirano
The mosaic-structured Vibrio cholerae genome points to the importance of horizontal gene transfer (HGT) in the evolution of this human pathogen. We showed that V. cholerae can acquire new genetic ...material by natural transformation during growth on chitin, a biopolymer that is abundant in aquatic habitats (e.g., from crustacean exoskeletons), where it lives as an autochthonous microbe. Transformation competence was found to require a type IV pilus assembly complex, a putative DNA binding protein, and three convergent regulatory cascades, which are activated by chitin, increasing cell density, and nutrient limitation, a decline in growth rate, or stress.
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