Several complaints arose from houses near an object bridge about rattling sounds caused by infrasound, a low-frequency noise in the 0 - 20 Hz frequency range. In Japan, conventional trucks with a rear leaf suspension have vibration frequencies of about 3.0 Hz; furthermore, their tire spring vibration frequency is 10 - 20 Hz. Infrasound is radiated from the bridge owing to the truck’s suspension spring vibration and/or tire spring vibration. In this study, the bridge vibrations were investigated using test trucks or conventional trucks to determine the cause of rattling sounds. It was found that the truck’s spring vibration caused excessive bending vibration in the object bridge; this in turn was transmitted to nearby houses as infrasound. Various preventive measures for infrasound were then considered, and their effectiveness was investigated through a simulation of the dynamic response using a running truck. The difference between each measure’s effectiveness as obtained by a comparison with each simulation’s result provided a clear picture about the infrasound reduction methods in consideration of both construction cost and working difficulty.

Background and Aim: Hepatic hydrothorax is one of the complications encountered in end stage liver disease. Pleural drainage carries the risk of massive protein and electrolyte depletion as well as the risk of bleeding and hepatic encephalopathy. Pleurodesis following pleural aspiration decreases the chance of pleural effusion recurrence, and has been a widely used long-standing method of controlling recurrent pleural effusions. The aim of this study is to evaluate the effect of pleurodesis using ultrasound-guided iodopovidone sclerotherapy in hepatic hydrothorax. Patients and Methods: This prospective study included 56 patients with clinical, laboratory and radiological evidence of liver cirrhosis and symptomatic right sided hepatic hydrothorax. All patients were subjected to repeated thoracentesis. Ten ml of lidocaine 2% were injected in the pleural space followed by 20 ml of iodopovidone. The follow-up was done after 3 months. Results: The sclerotherapy procedure was successful in 40 out of 56 cases (71.4%), and the success rate was 66.7% in massive effusion and reached 80% in moderate effusion. Twenty eight patients (50%) had to repeat the procedure for a second time, sixteen of which (28.6%) failed despite the second trial and twelve cases (21.4%) showed no fluid reaccumulation. Conclusion: Ultrasound-guided iodopovidone sclerotherapy is an effective approach for a successful pleurodesis in hepatic hydrothorax.