Background: The transmission mode of severe acute respiratory syndrome coronavirus 2 is primarily known as droplet transmission. However, a recent argument has emerged about the possibility of airborne transmission. On June 17, there was a coronavirus disease 2019 (COVID-19) outbreak in Korea associated with long distance droplet transmission. Methods: The epidemiological investigation was implemented based on personal interviews and data collection on closed-circuit television images, and cell phone location data. The epidemic investigation support system developed by the Korea Disease Control and Prevention Agency was used for contact tracing. At the restaurant considered the site of exposure, air flow direction and velocity, distances between cases, and movement of visitors were investigated. Results: A total of 3 cases were identified in this outbreak, and maximum air flow velocity of 1.2 m/s was measured between the infector and infectee in a restaurant equipped with ceiling-type air conditioners. The index case was infected at a 6.5 m away from the infector and 5 minutes exposure without any direct or indirect contact. Conclusion: Droplet transmission can occur at a distance greater than 2 m if there is direct air flow from an infected person. Therefore, updated guidelines involving prevention, contact tracing, and quarantine for COVID-19 are required for control of this highly contagious disease.

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This study observed the effect of different LED light colour on the behaviour and fear responses of broilers. In experiment 1, 400 broilers were placed into eight different light treatments. In experiment 2, six different light colours with five different age groups were considered. In experiment 1, use of a red and red-yellow mixed light significantly increased walking behaviour. Consequently, sitting and standing behaviour were found to be wavelength dependent, whereby short wavelength (blue, green-blue) treated birds spent more time sitting and standing than that under long wavelength (red, red-yellow). Consistently in experiment 2, birds spent more time feeding under the green treatment than with other treatments. Walking behaviour was significantly decreased and sitting and standing behaviour was increased under the blue light. Age also influenced the behaviour of broiler: young birds were more active than older birds. In addition, ground pecking and wing stretching behaviour were influenced by the wavelength of the light. Time of day did not influence the behaviour of the broilers. Under the red and red-yellow light treatments, birds spent longer in tonic immobility. Thus, the results suggest that red and red-yellow light activated the broiler's movement and fear responses while blue and greenblue decreased the movement and they spent more time sitting.

We evaluated the effect of monochromatic and combined light emitting diode (LED) light colour on performance, ovarian morphology, and reproductive hormone and biochemical blood parameters in laying hens. A total of 600 Hy-line Brown pullets, 12 weeks of age, were divided (25×4×6 = birds × replications × treatments) as follows: red (R), green (G), blue (B), and combinations of R→G and R→G→B treatments. Fluorescent white light (W) was the control. The results showed that higher egg production was found under the monochromatic R and combination R→G treatments, and that heavier eggs were laid by the B and G treatments (P<0.05). Consequently, better feed conversion ratio was attained in the R→G treatment. Serum follicle stimulating hormone and 17 -estradiol levels were significantly higher in the R and R→G treatments. B treated birds came into production 15 days later than those treated with R light. Organ weight (ovary and stroma) and ovarian follicle numbers (1-3 and 4-6 mm) were significantly higher in R treated birds, as well as serum glucose and triglyceride contents. Serum IgG concentrations and the heterophil to lymphocyte ratio were not influenced by light colour. In these laying hens, 14 h R with 2 h G light in the later part of the day increased reproductive hormone levels, ovarian weight, and follicle number and hence increased egg production. Thus, these results suggest that a combination of R→G light may be comparable with monochromatic R light to enhance egg production in laying hens.

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Saccharomyces cerevisiae was engineered to express different amount of heavy (H)-and light (L)-chain subunits of human ferritin by using a low-copy integrative vector (YIp) and a high-copy episomal vector (YEp). In addition to pep4::HIS3 allele, the expression host strain was bred to have the selection markers leu2 ؊ and ura3 ؊ for YIplac128 and YEp352, respectively. The heterologous expression of phytase was used to determine the expression capability of the host strain. Expression in the new host strain (2805-a7) was as high as that in the parental strain (2805), which expresses high levels of several foreign genes. Following transformation, Northern and Western blot analyses demonstrated the expression of H-and L-chain genes. The recombinant yeast was more iron tolerant, in that transformed cells formed colonies on plates containing more than 25 mM ferric citrate, whereas none of the recipient strain cells did. Prussian blue staining indicated that the expressed isoferritins were assembled in vivo into a complex that bound iron. The expressed subunits showed a clear preference for the formation of heteropolymers over homopolymers. The molar ratio of H to L chains was estimated to be 1:6.8. The gel-purified heteropolymer took up iron faster than the L homopolymer, and it took up more iron than the H homopolymer did. The iron concentrations in transformants expressing the heteropolymer, L homopolymer, and H homopolymer were 1,004, 760, and 500 g per g (dry weight) of recombinant yeast cells, respectively. The results indicate that heterologously expressed H and L subunits coassemble into a heteropolymer in vivo and that the iron-carrying capacity of yeast is further enhanced by the expression of heteropolymeric isoferritin.

The current study was designed to optimize solid phase microextraction (SPME)-GC-MS conditions for extraction and analysis of volatile components for Hanwoo beef and to establish a tentative database of flavor components. Samples were taken from Hanwoo longissimus muscle (30 mon old steer, 1 + B carcass grade) at 24 h postmortem. Results indicated that the optimum adsorption time for 75 µm CAR/PDMS fiber was 60 min at 60 o C. Thermal cleaning at 250 o C for 60 min was the best practice for decontamination of the fiber. A short analysis program with a sharp oven temperature ramp resulted in a better resolution and higher number of measurable volatile components. With these conditions, 96 volatile compounds were identified with little variation including 22 aldehydes, 8 ketones, 31 hydrocarbons, 12 alcohols, 8 nitrogen-and sulfurcontaining compounds, 5 pyrazines and 10 furans. A noticeable observation was the high number of hydrocarbons, aldehydes, ketones, alcohols and 2-alkylfurans which were generated from lipid decomposition especially the oxidation and degradation of unsaturated and saturate fatty acids. This implies that these compounds can be candidates for flavor specification of highly marbled beef such as Hanwoo flavor.

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