On weighting/reweighting schemes for approximate message passing algorithms

In this paper, we propose a number of weighting/reweighting schemes to improve the performance of the so-called approximate message passing (AMP) algorithm of Donoho et al. We consider the application of AMP for the recovery of sparse signals from an under-determined system of linear equations, and variants of AMP for the recovery of block sparse signals. The proposed schemes for block sparse signals cover both cases of known and unknown block borders. Simulation results, both in noiseless and noisy scenarios, show significant performance improvement over the standard AMP algorithm and a considerably better performance/complexity trade-off compared to other state-of-the-art recovery algorithms

Detection of extended-spectrum β-lactamase (ESBL) and plasmid-borne blaCTX-M and blaTEM genes among clinical strains of Escherichia coli isolated from patients in the north of Iran

Escherichia coli is an important cause of hospital-acquired infections worldwide. Antimicrobial resistance leads to treatment failure of hospital infections caused by E. coli. Production of extended-spectrum β-lactamases (ESBLs) is one of the major causes of antibiotic resistance in these bacteria. This study aimed to investigate the frequency of blaTEM and blaCTX-M genes in ESBL-producing E. coli strains isolated from clinical specimens of patients admitted to six hospitals in the north of Iran. A total of 160 E. coli strains were isolated from various clinical samples of hospitalised patients. Antibiotic resistance patterns were determined by the Kirby�Bauer disk diffusion method. The double-disk phenotypic confirmatory test was carried out amongst β-lactam-resistant isolates to detect ESBL-producing strains. Plasmid DNA of ESBL-producing strains was extracted and subjected to PCR for detection of the blaTEM and blaCTX-M genes, and isolates were extensively verified by sequencing. The highest resistance rate was to amoxicillin; all E. coli isolates (100) were susceptible to imipenem. Amongst the 160 clinical E. coli isolates, 83 (51.9) were ESBL-positive, of which 27 (32.5) and 72 (86.7) were positive for blaTEM and blaCTX-M, respectively. This study is the first report of an ESBL phenotype disseminated in hospitals in the north of Iran. These findings showed that there was a direct relationship between the development of resistance to β-lactam antibiotics and production of TEM and CTX-M enzymes. © 2016 International Society for Chemotherapy of Infection and Cance