RESUMO
As Coronavirus disease 2019 (COVID-19) continues to spread, a detailed understanding on the transmission mechanisms is of paramount importance. The disease transmits mainly through respiratory droplets and aerosol. Although models for the evaporation and trajectory of respiratory droplets have been developed, how the environment impacts the transmission of COVID-19 is still unclear. In this study, we investigate the propagation of respiratory droplets and aerosol particles generated by speech under a wide range of temperature (0 {degrees}C to 40 {degrees}C) and relative humidity (0% to 92%) conditions. We show that droplets can travel three times farther in low temperature and high humidity environment, while the amount of aerosol increases in high temperature and low humidity environment. The results also underscore the importance of proper ventilation, as droplets and aerosol spread significantly farther in airstreams. This study contributes to the understanding of the environmental impact on COVID-19 transmission.
RESUMO
Objective:To explore whether endoscopic surgery can achieve the same effect on thyroid cancer as open surgery.Method:44 cases were selected to endoscopic thyroidectomy with breast areola approach, who were prepared to accept the surgical treatment of thyroid cancer with cT1N0 stages, female, ≤60 years old, no history of neck surgery and beauty desire. Fifty patients with the same conditions undergoing thyroid open surgery were as the control group.Results:Operative time of endoscopic group[ (170.0±28.0) min] was longer than that of the open operation group[ (90.0±21.0) min ( t=15.610, P=0.000) ]. There was no significant difference between the two groups in surgical complications ( P>0.05) . There was no statistical difference between the number of paratracheal and anterior tracheal lymph nodes of endoscopic group (6.0 ±4.2) and open surgery group (5.5 ±3.7) ( t=0.692, P>0.05) . There was no statistical difference between the number of anterior laryngeal lymph nodes of endoscopic group (0.7 ±1.1) and open surgery group (0.5 ±0.9) ( t=1.186, P>0.05) . Conclusion:The breast areola approach endoscopic thyroidectomy is safe and reliable in treatment of thyroid cancer, and the central cervical lymph node dissection is sufficient, which can be used as the choice of operation mode for thyroid cancer patients in cT1N0 stage.
