The abdomen has been variously characterized as a hydrostatic system, in which pressures exhibit a gravitational gradient and pressure fluctuations are spatially uniform, and as a compartment, in which pressure gradients are not simply gravitational and pressure fluctuations differ markedly from place to place. To characterize the pressures acting on the ventral abdominal wall, we used saline-filled catheters and air-filled balloons in anesthetized dogs in various body positions during spontaneous breathing and mechanical ventilation. Pressures were measured in the stomach and at multiple sites next to the abdominal wall. Under most circumstances, measurements next to the abdominal wall exhibited a hydrostatic gravitational gradient of approximately 0.89 cmH2O/cm height and pressure fluctuations were spatially homogeneous. Deviations from this hydrostatic behavior were seen when abdominal pressures were compared with gastric pressures, when measurements were made with a balloon catheter, and when the lower abdomen was constricted with a binder. Analysis of these and previously published data suggests that the abdomen does, at times, behave like a hydraulic system but can deviate from simple hydrostatic behavior to the extent that shape-stable abdominal viscera are deformed.
Aircraft landing and taking off at Narita International Airport in Japan frequently report low-level wind shear (LLWS), which is a local variation in the wind vector, and turbulence when the prevailing wind is southwesterly, which is crosswind to the runway. On 20 June 2012, just before touchdown, an arriving aircraft at this airport encountered LLWS that consisted of a sudden change in the wind vector from a headwind component of 5 knots (2.6 m s −1) to a tailwind component of 10 knots (5.1 m s −1). This caused a rather hard landing. As the aircraft approached, none of cumulonimbus clouds, fronts, or wind shear lines were observed around the airport. Further analysis of the data measured by the landing aircraft and observations made by the Doppler lidar revealed that the LLWS was caused by horizontal roll vortices that developed in the atmospheric boundary layer (ABL) over the Shimofusa tableland surrounding the airport. The axes of these horizontal roll vortices were nearly parallel to the mean wind direction, while their horizontal and vertical scales were approximately 800 m and 500 m, respectively. In our present study, we demonstrate that the existence of such horizontal roll vortices that cause LLWS can be effectively detected by a single Doppler lidar that utilizes backscattering from aerosols. Although the LLWS associated with horizontal roll vortices has a smaller magnitude than those caused by a microburst, gust front, or front, landing aircraft often encounter these horizontal roll vortices just before touchdown with a much higher probability than other phenomena since horizontal roll vortices occur at a horizontal spacing of approximately 800 m over a wide area during the daytime hours of a clear day.
A poly(pyridazine) film which is blue in colour with an electrical conductivity of 10 S/cm has been obtained, for the first time, by the electrochemical oxidation of pyridazine.
An accident occurred when an aircraft landed at Narita International Airport, Japan, on 20 June 2012. The aircraft encountered rapid changes of winds together with strong turbulence, although the weather was fair. In the present study, a two‐domain nested regional weather prediction models are used. The results in the outer domain show that southwesterly winds associated with a synoptic extratropical cyclone were locally accelerated to the southwest of the airport resulting in strong vertical shear. The simulation in the inner domain reproduces horizontal convective rolls, which are similar to those observed by a Doppler lidar at the airport. The wind velocity component parallel to the runway had a spatial variation of about 10 m s
−1. The present approach using a large eddy simulation is useful for clarifying environments and features of horizontal convective rolls and forecasting low‐level wind shear associated with them, which can be a significant risk for aircraft.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.