We report the description of a new plasmid-encoded AmpC-type beta-lactamase gene (bla(CMY-11)) from Escherichia coli K983802.1 that was isolated from a patient in South Korea suffering from a urinary tract infection. Antibiotic susceptibility testing, plasmid analysis, pI determination, transconjugation and Southern blot analysis were carried out to investigate the resistance mechanism to cefoxitin. PCR, sequencing and sequence analysis were used to identify and analyse the beta-lactamase gene (bla(CMY-11)) responsible for the cefoxitin resistance. CMY-11 and bla(CMY-11) are compared with other class C beta-lactamases and their genes to determine phylogenetic relationships. The cefoxitin-resistance phenotype of E. coli K983802.1 reflects the presence of a large plasmid [pYMG-2 (130 kb)]. A beta-lactamase with a pI value of 8.0 from a transconjugant of E. coli K983802.1 was identified by isoelectric focusing. A 1478 bp DNA fragment from pYMG-2 containing bla(CMY-11) was sequenced and an open reading frame coding for a 382 amino acid peptide (CMY-11) was found. Phylogenetic analysis clearly shows that bla(CMY-11) belongs to the group of ampC-related bla genes. It is likely that bla(CMY-11) evolved from bla(CMY-1) via bla(CMY-10).
We consider the IEEE 802.16 OFDMA system with the frequency diversity frame structure. We perform adaptive coding and modulation, allocation of the time-frequency resource and transmit power to the downlink and uplink service flows, scheduled for transmission in the current frame. We also adapt the position of the frame boundary between the uplink and downlink subframes. We propose three heuristic algorithms that minimize the total power transmitted in both downlink and uplink subframes subject to the maximum transmission power constraints and the available time-frequency resource constraint, while satisfying the QoS requirements for all downlink and uplink service flows scheduled for transmission. Our algorithms take into account the MAC and PHY layers processing in case of ARQ. We evaluate the proposed heuristic algorithms by the system level simulation of the IEEE 802.16 network.
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