Occurrence and characterization of shiga toxin-producing Escherichia coli in raw meat, raw milk, and street vended juices in Bangladesh

The major objective of this study was to investigate the prevalence of Shiga toxin (Stx)–producing Escherichia coli (STEC) in different types of food samples and to compare their genetic relatedness with STEC strains previously isolated from animal sources in Bangladesh. We investigated a total of 213 food samples, including 90 raw meat samples collected from retail butcher shops, 20 raw milk samples from domestic cattle, and 103 fresh juice samples from street vendors in Dhaka city. We found that more than 68% (n=62) of the raw meat samples were positive for the stx gene(s); 34% (n=21) of buffalo meats and 66% (n=41) of beef. Approximately 10% (n=2) of the raw milk and 8% (n=8) of the fresh juice samples were positive for stx. We isolated STEC O157 from seven meat samples (7.8%), of which two were from buffalo meats and five from beef; and no other STEC serotypes could be isolated. We could not isolate STEC from any of the stx-positive raw milk and juice samples. The STEC O157 isolates from raw meats were positive for the stx2, eae, katP, etpD, and enterohemorrhagic E. coli hly virulence genes, and they belonged to three different phage types: 8 (14.3%), 31 (42.8%), and 32 (42.8%). Pulsed-field gel electrophoresis (PFGE) typing revealed six distinct patterns among seven isolates of STEC O157, suggesting a heterogeneous clonal diversity. Of the six PFGE patterns, one was identical and the other two were =90% related to PFGE patterns of STEC O157 strains previously isolated from animal feces, indicating that raw meats are readily contaminated with fecal materials. This study represents the first survey of STEC in the food chain in Bangladesh

Personality maturation through sense of mastery? Longitudinal evidence from two education‐to‐work transition studies

ObjectiveWhy personality changes in young adulthood remains a critical theoretical and empirical question. We studied personality change during the education-to-work transition, including mean-level personality change and its specific timing, the degree of individual variability in change, and the link between sense of mastery and personality change. MethodsWe used two intensive longitudinal studies. Study 1 included 5 waves of data across 2 years during the university-to-work transition (N = 309; mean-aged 25). Study 2 included 3 waves of data across 8 months during an internship-heavy teacher education program (N = 317; mean-aged 22). We measured personality traits and work-related mastery with questionnaires and personality states and general mastery with the experience sampling method. ResultsFirst, we found no evidence for mean-level personality maturation but decreases in trait Conscientiousness. Second, young adults differed significantly in personality trait and state change. Third, young adults with higher levels of work-related sense of mastery showed more positive changes in trait Conscientiousness. Decreases in general sense of mastery predicted later decreases in state Emotional Stability and vice versa. Change in general sense of mastery correlated with personality state change. ConclusionsSense of mastery seems to be part of a dynamic short-term process underlying personality change in young adulthood.</p

Plasmonic LED device

Plasmonic nanostructures are known to influence the emission of near-by emitters. They can enhance the absorption and modify the external quantum efficiency of the coupled system. To evaluate the possibility of using plasmonics to enhance the light emission of a phosphor-converted LED device and create an efficient directional light source, regular arrays of aluminium nanoparticles covered with a red dye layer are investigated. In arrays of aluminum nanocylinders with a diameter of ca 140 nm combined with a thin (650 nm) layer of luminescent material, very narrow resonances have been observed, which lead to large enhancement factors of up to 70 and 20 for excitation with a directional blue laser source and a lambertian LED respectively, in a small spectral range for particular angles. The measured resonances agree very well with finite-difference time-domain numerical simulations. These changes in the angular emission profile of the red dye as well as the spectral shape of its emission can help to optimize the efficacy of phosphor-converted LED modules and increase the amount of useable light in a certain angular cone. Using Fourier microscopy, large modifications of the angular emission profile as well as spectral shaping are observed for these plasmonic LED devices if compared to reference samples without plasmonic nanostructures