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Coronavirus disease (COVID-19) has infected many people worldwide. As the probability of being infected by the virus increases with an increase in the number of people gathered in an indoor space, methods for reducing its spread indoors are urgently required. In this study, a classroom with 25 students was considered as an indoor space, and an attempt was made to devise a method to reduce the concentration of the viruses generated indoors more effectively. Through numerical analysis, the age of air inside the classroom was compared and analyzed when both the air cleaner and natural ventilation were used. The age of air varied locally in the classroom depending on the position of the air cleaner, confirming its importance in effectively removing particles possibly containing viruses generated indoors. When the air cleaner flow rate was doubled, the age of air was almost halved, implying that the concentration of the particles including viruses generated indoors can be reduced efficiently by increasing the air cleaner flow rate. Natural ventilation performed by completely opening the windows and doors of the classroom reduced the age of air. It was observed that the operation of the air cleaner along with open windows and doors of the classroom reduced the concentration of the particles including viruses generated indoors more effectively. More specifically, when both natural ventilation and air cleaner were applied, the age of air decreased by almost 50% compared with the only air cleaner case and by about 22% compared with the only natural ventilation case. Copyright (c) 2021 American Association for Aerosol Research

Purpose: To evaluate the diagnostic capabilities of the low-field (0.2T) magnetic resonance (MR) system in the detection of the superior labrum anterior to posterior (SLAP) lesion. Materials and Methods: One hundred fifty patients underwent magnetic resonance imaging of the shoulder over a 7-month period. Forty-six patients underwent arthroscopic surgery, and the surgical results were correlated with the findings of the MR imaging. Arthroscopic procedures were performed within a mean of 8 days after MR imaging. MR imaging of the shoulder was conducted as follows: shoulder coil; T1-weighted spin echo, coronal-oblique images; T2-weighted gradient echo, coronal-oblique and axial images; and T2-weighted spin echo, coronal-oblique and sagittal-oblique images. Prospectively, one radiologist interpreted the MR images. Results: The results of surgery were as follows: SLAP II in 26 shoulders, SLAP III in 1 shoulder, SLAP IV in 1 shoulder, normal labrum in 6 shoulders. For SLAP lesions with a higher grade than type 2, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the low-field MRI were 85.7%, 55.5%, 75%, 71%, and 74%, respectively. Conclusion: There was relatively good agreement for the comparison of the MR results obtained using a low-field MR system with the surgical findings for identifying SLAP lesions.

Purpose: We wished to compare the ability of ultrasonography and radiography performed on the same day to detect rib fractures in minor chest injuries. Materials and Methods: Two hundred and fifteen patients with minor chest injuries were selected. Radiography and ultrasonography were performed on the same day with these patients. Chest wall pain was the only presenting symptom. Two radiologists performed ultrasonography. Fractures were identified by a disruption of the anterior margin of the rib and costal cartilage. The incidence and location of fractures and complications revealed by radiography and ultrasonography were compared. Results: Radiographs revealed the presence of 70 rib fractures in 50 (23%) of 215 patients and ultrasonography revealed the presence of 203 rib fractures in 133 (62%) of 215 patients. Ultrasonography uniquely identified 133 rib fractures in 83 patients. Ultrasonography identified a 2.9 fold increase in the number of fractures in a 2.6 fold number of subjects as compared to radiography. Of the 203 sonographically detected fractures, 201 were located in the rib, one was located at the costochondral junction, and one in the costal cartilage. There were no complications seen by either radiography or ultrasonography. Conclusion: Ultrasonography reveals more fractures than those that may be overlooked on radiography for minor chest injuries.

We designed this study to evaluate the functional outcome and to suggest the guidelines in the treatment of bimalleolar ankle fractures with clinical and radiological analysis after operative treatment. We analyzed 36 patients with bimalleolar fractures among 90 ankle fractures and followed up for more than 1 year. All 36 fractures were classified according to Lauge-Hansen system and the Meyer criteria was used for the clinical and radiological assessment. Seventeen cases(47%) were supination-external rotation(47%); 9 cases(25%) were supinationadduction; 6 cases(17%) were pronation-abduction and 4 cases(11 %) were pronation-external rotation type. Satisfactory results was obtained in 32 cases(89%) according to the criteria of Meyer in the viewpoint of clinical and radiological analysis. Satisfactory results could be obtained with early anatomical reduction and rigid internal fixation for the treatment of bimalleolar ankle fractures. Distal tibiofibular syndesmosis disruption could be spontaneously reduced without trans-syndesmotic screw fixation by early