Large-scale experiment to assess the collision impact force from a tsunami wave on a drifting castaway.

Although most fatalities in tsunami-related disasters are conjectured to be a result of drowning, injury risk owing to collision with other floating debris or fixed buildings has not been studied sufficiently. In this study, the impact force corresponding to the collision of a concrete block and drifting test body in a tsunami wave was experimentally investigated, and the injury risk was evaluated in terms of different biomechanical indexes; specifically, maximum acceleration, head injury criterion, and impact force. The injury risk indicated by the considered indexes was reasonably low. It was noted that if a healthy adult collided with a concrete wall under a velocity of 2.5 m s-1 and wave height of 0.59 m, the adult would likely not be critically injured. However, a similar collision impact poses considerable risk to infants and children, as well as the more sensitive regions of the adult body. Moreover, in the case of large tsunamis, such as that in the 2011 Great East Japan Earthquake, a drifting person may be at considerable risk for injuries. The collision impact occurring on the tip of a surge flow is notably significantly larger than that on a bore flow. This is because a surge flow, which arrives at the concrete block earlier than a bore flow, forms a certain water layer along the concrete wall and that layer acts as a cushion for any body drifting on the bore flow, indicating the importance of such a buffering effect. These findings can provide practical guidance regarding the formulation of effective tsunami-protection measures.

Potential technique for improving the survival of victims of tsunamis.

We investigated a method for surviving tsunamis that involved the use of personal flotation devices (PFDs). In our work, we succeeded in numerically demonstrating that the heads of all the dummies wearing PFDs remained on the surface and were not dragged underwater after the artificial tsunami wave hit them. In contrast, the heads of all the dummies not wearing PFDs were drawn underwater immediately; these dummies were subsequently entrapped in a vortex. The results of our series of experiments are important as a first step to preventing the tragedies caused by tsunamis.

Localized small-bowel infarction caused by Aspergillus during chemotherapy for acute myeloid leukemia: report of a case.

Aspergillosis is a common fungal infection in immunocompromised patients undergoing chemotherapy. The incidence of invasive fungal infection in these patients has increased dramatically in recent years. We report a case of small-bowel infarction caused by Aspergillus in a 48-year-old man who was receiving chemotherapy for acute myeloid leukemia. On day 20 after the start of chemotherapy, right lower abdominal pain and rebound tenderness developed, with a high fever. A contrast-enhanced computed tomography scan showed a semicircular perfusion defect in the ileum. Thus, we performed partial resection of the ileum with primary anastomosis. Macroscopically, the ileum had mucosal ulcerations. Microscopically, there was transmural necrosis with microperforation and Aspergillus invading necrotic tissue and blood vessels. The patient had an uneventful postoperative course and was discharged 14 days after the procedure. Intestinal aspergillosis is rare and associated with high mortality. Thus, it should be considered in the differential diagnosis of neutropenic patients with sudden abdominal pain and fever.

Rupture of a pancreaticoduodenal artery aneurysm into the common bile duct resulting in fatal suppurative cholangitis: report of a case.

A 73-year-old man with a preoperative diagnosis of cholangitis underwent a laparotomy, which revealed a necrotized gallbladder and dilated common bile duct, both filled with foul-smelling clotted blood. We could not find the cause of hemobilia at this time. On postoperative day (POD) 11, an exsanguinating hemorrhage suddenly began pouring from the T-tube, suggesting the possibility of a ruptured gastroduodenal artery branch aneurysm into the biliary system. Immediate angiography confirmed multiple aneurysms of the gastroduodenal artery. Embolization was done and there was no further bleeding from the T-tube; however, the patient's condition was too critical for recovery and he died on POD 17. At autopsy, we found multiple aneurysms in the gastroduodenal artery. The posterior superior pancreaticoduodenal artery, diverging from one of the aneurysms of the gastroduodenal artery, formed another tiny aneurysm subjacent to the common bile duct wall. Rupture of this aneurysm into the biliary system caused fatal acute obstructive suppurative cholangitis.