An earth-stationary perceived visual scene during roll and yaw motions in a flight simulator

A flight simulator was used for two experiments to determine the amplitude combinations of visual scene motion (with respect to the observer) and inertial body motion (with respect to an earth-fixed frame) that provide the perception of an earth-stationary visual scene and realistic simulated self-motion. In the first experiment, this range was determined for simulated self-motion about the longitudinal body axis, while in the second, self-motion about the vertical body axis was considered. Both the inertial and the visual motions consisted of 0.75 a accelerations, followed by 1.50 s decelerations, and 0.75 s accelerations. The visual scene acceleration amplitude, W, was fixed at either 0, 2, 4, 8, or 12 degrees/s2 while the inertial acceleration amplitude, I, was varied by a staircase procedure. Following the visual and inertial motions, the subjects pushed a button when they perceived the scene to be not earth-stationary. At each visual scene acceleration amplitude, the lower and upper inertial threshold amplitudes were determined, which bounded the range in which the visual scene was perceived to be earth-stationary. The lower and upper inertial thresholds were defined as the inertial motion amplitudes for which the inertial stimulations were too small or too large, respectively, to provide the perception of an earth-stationary visual scene. The lower inertial thresholds were determined for W = 2 through W = 12 degrees/s2 and were found to be well approximated by the linear relation I = -0.37 + 0.60 W for the roll motions tested, and I = 1.1 + 0.33 W for the yaw motions tested. The upper inertial thresholds were determined for W = 0 through W = 12 degrees/s2 and were found to be well approximated by the linear relation I = 2.7 + 1.7 W for roll and I = 2.2 + 1.4 W for yaw. With the assumption that the lower and upper inertial threshold amplitudes are symmetric about the W = 0 condition, the present results infer a strong nonlinearity of the thresholds near W = 0.     

Activation-inactivation coupling in Myxicola giant axons injected with tetraethylammonium

Myxicola giant axons internally injected with tetraethylammonium chloride to block potassium currents were examined under voltage clamp. The sodium inactivation time constants obtained from the decline in INa during step depolarizations were substantially smaller than those obtained using conditioning prepulses to the same potentials and the ratios agreed with previous observations using TTX. Inactivation shifts were also measured and found to be comparable to previous results.     

Effect of skin or muscle incisions or the loss of blood on serum leucogenenol level

It has been found that damage to a tissue of a rabbit or a rat, such as results from a skin incision or an incision through the skin and muscles into the abdominal cavity, is followed 24 hr later by a significant increase in the concentration of leucogenenol in the animal's serum. Likewise, loss of approximately one-quarter to one-half of the blood in the circulation of rabbits or rats causes an increase 24 hr later in the animals' serum leucogenenol concentration.     

The value of baseline chest radiograph reports in the care of elderly patients in an emergency department

The authors used a before/after research design to determine the impact of written reports of baseline chest radiographs (CXRs) on the care of elderly patients during 48 emergency department visits. Internal medicine housestaff completed questionnaires that included inquiries about their treatment plans for the patients both before and after they reviewed reports of baseline CXR results. The investigators compared these answers to determine the proportion of patients for whom baseline CXR reports changed patient management. In addition, three faculty reviewers used the nominal group process, a consensus analysis approach, to measure treatment changes and to estimate benefit to the patients from the alterations in management. The housestaff indicated that written baseline CXR reports caused them to change treatment plans during only 2 (4%) of the 48 visits. In both cases, they provided aggressive treatment for congestive heart failure because of baseline CXR results. The faculty reviewers could find only one case in which baseline CXR findings might have changed their management plans. Moreover, they were not convinced that the treatment changes indicated by the housestaff actually benefitted the patients. These results suggest that written reports of baseline CXRs do not improve the care of acutely ill patients in an emergency department setting.     

Prenatal diagnosis of periventricular hemorrhage by fetal brain magnetic resonance imaging

The neonate is unable to relate specific complaints of pain and may not exhibit the usual signs of illness or infection. Septic arthritis of the hip is a surgical emergency in the neonate, and it should be considered in any irritable or ill child who has a high index of suspicion. Prompt diagnosis and immediate treatment are necessary. Nearly all babies undergo routine examination of the hip for dysplasia. It is recognized that limitation of abduction of the hip in the neonate may not represent developmental dysplasia of the hip but may represent other etiologies, such as fracture, infection, congenital anomaly, or tumor. The following case report illustrates the importance of careful clinical evaluation of an apparent asymptomatic neonate.