The instability of wake of an axisymmetric body with the NACA aerofoil section was experimentally studied under low background turbulence. The body was suspended using a magnetic suspension and balance system to avoid undesirable influences of mechanical supports on the disturbance development. The Reynolds number based on the chord length of the aerofoil section ranged from 5.3 × 104 to 2.1 × 105. For the body with a NACA0015 aerofoil section where there is no boundary-layer separation on the body surface, the wake was convectively unstable, even at the highest Reynolds number examined. Although the wake maintained axisymmetry of mean flow, the instability waves often took a planar-symmetric form, indicating that the occurrence of disturbance can be influenced by minute variations in the position and orientation of the suspended body. For bodies with thicker NACA0018 and NACA0024 aerofoil sections where the flow involved a region of absolute instability immediately downstream of the trailing edge, the global mode could grow rapidly and attain saturation amplitude within a very short distance from the trailing edge despite that the region of absolute instability was limited only to small streamwise distance, about one tenth of the instability wavelength. The predominant frequency of vortex shedding was found to be very close to the absolute frequency near the trailing edge, especially at the upstream boundary of the region of absolute instability. This is consistent with the theoretical model for the development of a nonlinear global mode. It was also found that the mean flow axisymmetry was broken around the critical Reynolds number for global instability, which led to the appearance and growth of a planar-symmetric global mode.

Two-dimensional local wall suction is applied to a fully developed turbulent boundary layer such that near-wall turbulence structures are completely sucked out, but most of the turbulent vortices in the original outer layer can survive the suction and cause the resulting laminar flow to undergo re-transition. This enables us to observe and clarify the whole process by which the suction-surviving strong vortical motions give rise to near-wall low-speed streaks and eventually generate wall turbulence. Hot-wire and particle image velocimetry (PIV) measurements show that low-frequency velocity fluctuations, which are markedly suppressed near the wall by the local wall suction, soon start to grow downstream of the suction. The growth of low-frequency fluctuations is algebraic. This characterizes the streak growth caused by the suction-surviving turbulent vortices. The low-speed streaks obtain almost the same spanwise spacing as that of the original turbulent boundary layer without the suction even in the initial stage of the streak development. This indicates that the suction-surviving turbulent vortices are efficient in exciting the necessary ingredients for the wall turbulence, namely, low-speed streaks of the correct scale. After attaining near-saturation, the low-speed streaks soon undergo sinuous instability to lead to re-transition. Flow visualization shows that the streak instability and its subsequent breakdown occur at random in space and time in spite of the spanwise arrangement of streaks being almost periodic. Even under the high-intensity turbulence conditions, the sinuous instability amplifies disturbances of almost the same wavelength as predicted from the linear stability theory, though the actual growth is in the form of a wave packet with not more than two waves. It should be emphasized that the mean velocity develops the log-law profile as the streak breakdown proceeds. The transient growth and eventual breakdown of low-speed streaks are also discussed in connection with the critical condition for the wall-turbulence generation.

Penetrating cardiac injuries commonly occur secondary to gunshot or stab wounds. This is a report an unusual case of a patient who sustained a penetrating cardiac injury due to a nail from a terrorism-related, nail-bomb explosion. Associated problems included pericardial tamponade, penetrating cardiac injuries, acute, traumatic, myocardial infarction, and a penetrating lung injury. Prompt diagnosis and aggressive surgical intervention resulted in full recovery of the patient.

The lack of a universally applicable definition of terrorism has confounded the understanding of terrorism since the term was first coined in 18th Century France. Although a myriad of definitions of terrorism have been advanced over the years, virtually all of these definitions have been crisis-centered, frequently reflecting the political perspectives of those who seek to define it.

In this article, we deconstruct these previously used definitions of terrorism in order to reconstruct a definition of terrorism that is consequence-centered, medically relevant, and universally harmonized. A universal medical and public health definition of terrorism will facilitate clinical and scientific research, education, and communication about terrorism-related events or disasters.

We propose the following universal medical and public definition of terrorism: The intentional use of violence — real or threatened — against one or more non-combatants and/or those services essential for or protective of their health, resulting in adverse health effects in those immediately affected and their community, ranging from a loss of well-being or security to injury, illness, or death.

Although the 1995 Tokyo subway sarin attack probably was the most widely reported terrorist event in Japan to date (5,500 injured, 12 dead), the country has suffered numerous other large terrorism-related events in recent decades, including bombings of the headquarters of Mitsubishi Heavy Industries in Tokyo in 1974 (207 injured, 8 dead), the Hokkaido Prefectural Government office building in Sapporo in 1976 (80 injured, 2 dead), and the Yosakoi-Soran Festival in Sapporo in 2000 (10 injured, none dead). Japan also has experienced two other mass-casualty terrorist events involving chemical releases, including the 1994 Matsumoto sarin attack (600 injured, 7 dead) and the 1998 Wakayama arsenic incident (67 injured, 4 dead).

Until 1995, emergency management in Japan focused on planning and preparedness at the local level for the frequent disasters caused by natural events. Since that time, substantial progress has been made in advancing emergency planning and preparedness for terrorism-related events, including the designation of disaster centers in each prefecture, the implementation of several education and training programs for nuclear, biological, and chemical terrorism, and the establishment of a national Antiterrorism Office within the Ministry of Health, Labor, and Welfare.