Let F be a life distribution,F=1-F. F is called a distribution function with decreasing failure rate average (DFRA), if-log(t) is decreasing in t>0. In this paper, using constructive method, sharp upper and lower b...Let F be a life distribution,F=1-F. F is called a distribution function with decreasing failure rate average (DFRA), if-log(t) is decreasing in t>0. In this paper, using constructive method, sharp upper and lower bounds of F(t) are given where F∈DFRA with known mean and variance. In addition, brief tables are provided for practical use.展开更多
Objective To identify the antimicrobial resistance of commercial lactic acid bacteria present in microbial foods and drug additives by analyzing their isolated strains used for fermentation and probiotics. Methods Ant...Objective To identify the antimicrobial resistance of commercial lactic acid bacteria present in microbial foods and drug additives by analyzing their isolated strains used for fermentation and probiotics. Methods Antimicrobial susceptibility of 41 screened isolates was tested with disc diffusion and E-test methods after species-level identification. Resistant strains were selected and examined for the presence of resistance genes by PCR. Results Distribution of resistance was found in different species. All isolates were susceptible to chloramphenicol, tetracycline, ampicillin, amoxicillin/clavulanic acid, cephalothin, and imipenem. In addition, isolates resistant to vancomycin, rifampicin, streptomycin, bacitracin, and erythromycin were detected, although the incidence of resistance to these antibiotics was relatively low. In contrast, most strains were resistant to ciprofloxacin, amikacin, trimethoprim/sulphamethoxazole, and gentamycin. The genes msrC, vanX, and dfrA were detected in strains of Enterococcus faecium, Lactobacillus plantarum, Streptococcus thermophilus, and Lactococcus lactis. Conclusion Antibiotic resistance is present in different species of probiotic strains, which poses a threat to food safety. Evaluation of the safety of lactic acid bacteria for human consumption should be guided by established criteria, guidelines and regulations.展开更多
An S band and a C band distributed fiber Raman amplifiers (DFRAs) with flattened gain and compensated dispersion have been studied and implemented with 1427 nm and 1455 nm mono-wavelength fiber Raman lasers as the pum...An S band and a C band distributed fiber Raman amplifiers (DFRAs) with flattened gain and compensated dispersion have been studied and implemented with 1427 nm and 1455 nm mono-wavelength fiber Raman lasers as the pumped sourcesrespectively. The gain of single-wave pumped S band and C band can reach 10 dB and 15 dB respectively. And a 50 nmgain flattened width was successfully obtained by using a chirp fiber Bragg grating (CFBG) gain flattened filter with gainripple of ±0.6 dB. The C band DFRA has been applied to CDMA wireless communication system successfully.展开更多
文摘Let F be a life distribution,F=1-F. F is called a distribution function with decreasing failure rate average (DFRA), if-log(t) is decreasing in t>0. In this paper, using constructive method, sharp upper and lower bounds of F(t) are given where F∈DFRA with known mean and variance. In addition, brief tables are provided for practical use.
文摘Objective To identify the antimicrobial resistance of commercial lactic acid bacteria present in microbial foods and drug additives by analyzing their isolated strains used for fermentation and probiotics. Methods Antimicrobial susceptibility of 41 screened isolates was tested with disc diffusion and E-test methods after species-level identification. Resistant strains were selected and examined for the presence of resistance genes by PCR. Results Distribution of resistance was found in different species. All isolates were susceptible to chloramphenicol, tetracycline, ampicillin, amoxicillin/clavulanic acid, cephalothin, and imipenem. In addition, isolates resistant to vancomycin, rifampicin, streptomycin, bacitracin, and erythromycin were detected, although the incidence of resistance to these antibiotics was relatively low. In contrast, most strains were resistant to ciprofloxacin, amikacin, trimethoprim/sulphamethoxazole, and gentamycin. The genes msrC, vanX, and dfrA were detected in strains of Enterococcus faecium, Lactobacillus plantarum, Streptococcus thermophilus, and Lactococcus lactis. Conclusion Antibiotic resistance is present in different species of probiotic strains, which poses a threat to food safety. Evaluation of the safety of lactic acid bacteria for human consumption should be guided by established criteria, guidelines and regulations.
基金This work was supported by Great Scientific Research Project ofZhejiang Province, China (No.021101558)a part of projectfunds of the Korea-China Optical Technology Research Center.
文摘An S band and a C band distributed fiber Raman amplifiers (DFRAs) with flattened gain and compensated dispersion have been studied and implemented with 1427 nm and 1455 nm mono-wavelength fiber Raman lasers as the pumped sourcesrespectively. The gain of single-wave pumped S band and C band can reach 10 dB and 15 dB respectively. And a 50 nmgain flattened width was successfully obtained by using a chirp fiber Bragg grating (CFBG) gain flattened filter with gainripple of ±0.6 dB. The C band DFRA has been applied to CDMA wireless communication system successfully.
