Biomedical subjects

J H Raddin

Publications and source records attributed to J H Raddin.

6 recordsLinked to original sources

PubMed1994

A new source for vestibular illusions in high agility aircraft.

The enhanced maneuverability aircraft of the future will expose pilots to combinations of conventional translational accelerations as well as extraordinary angular accelerations. This flight regime, combined with the intense concentration required for combat maneuvering, will make motion-induced illusions more perilous than in existing aircraft. Although there are many causes for disorientation, theoretical analysis indicates two in particular, the "G-excess" and "cross-coupling" illusions, may be invoked by a new and distinctly different stimulus. These two illusions, which are both typically induced by motion of the pilot's head, may in addition be created by rotation of the aircraft with respect to its flight path. After comparing typical pilot head movements to projected decoupled angular motion capabilities of supermaneuverable aircraft, we conclude that the potential exists for G-excess or cross-coupling illusions in a high agility aircraft independent of pilot head motion with respect to the aircraft.

Acceleration↗

PubMed1991

Assessing neck extension-flexion as a basis for temporomandibular joint dysfunction.

In the August 1987 issue of the Journal of Oral and Maxillofacial Surgery, Weinberg and LaPointe published an article entitled "Cervical Extension-Flexion Injury (Whiplash) and Internal Derangement of the Temporomandibular Joint" in which they proposed an explantation for injury to the temporomandibular joint resulting from certain motor vehicle accidents. In this article, the previous mechanism is assessed and the authors conclude that it is inaccurate.

Acceleration↗

PubMed1987

A perspective on human performance as the limiting factor in aircraft performance.

The popular notion appears to be growing that the human is the limiting factor in aircraft performance. Proponents cite recent instances of pilot loss of consciousness during maneuvers. The aerospace medicine perspective differs, seeing the aircraft not as a vehicle in which to make hard turns, but as a mission-directed weapon system for which the pilot is the enabling factor. Various "human limiting factors" are described among requirements staffs, developers, researchers, trainers, and operators. A plea is made to pursue available avenues to improve manned weapon system performance and to see even our most sophisticated weapons as human instruments.

Aerospace Medicine↗

PubMed1985

Knee ligament injury during lateral impact.

A volunteer woman subject incurred injury to her right knee consisting of a torn anterior cruciate ligament and stretched medial collateral ligament during a lateral (+Gy) impact test. Similar injury has not been reported in the English-language literature an accidental sideward automotive crashes or lateral impact experimentation involving humans. The primary mechanism which produced this injury was external tibial rotation on the femur with the knee flexed. The factors contributing to the injury included extraordinarily forceful leg bracing by the subject, her knee joint laxity or hypermobility, and the absence of side supports to limit lower extremity flailing during the impact response. In future lateral impact tests, women subjects should be used with caution and any subject with abnormal joint mobility should be excluded from participation.

Adult↗

PubMed1983

Vertical impact evaluation of the F/FB-111 crew restraint configuration, headrest position, and upper extremity bracing technique.

An experiment to assess the influence of changes in restraint harness configuration, fore-aft headrest position, and upper extremity bracing technique on human response to impact was conducted using the AFAMRL Vertical Deceleration Tower. A total of 201 tests was performed with volunteer subjects in 11 test conditions to evaluate 3 restraint harnesses, 3 arm bracing conditions, and 4 seat adjustment configurations. The test fixture, restraint harness, and subject were instrumented to obtain pertinent objective data during each experiment. Measured parameters included acceleration of the impact carriage and test seat, velocity of the carriage, loads reacted at the seat, loads measured at the restraint harness attachment points, triaxial translational accelerations at the head and chest of the subject, and body segment displacements. The mean peak carriage acceleration for the 161 experimental level tests was 10.5 G (S.D. = 0.18) and the mean carriage velocity change was 7.89 m/s (S.D. = 0.05). Resultant head and chest accelerations were increased in a proposed, modified F/FB-111 restraint system compared to the operational F/FB-111 restraint system. These findings contributed to the decision not to implement the proposed modification. Also, the arms crossed bracing position for F/FB-111 ejectees preparing for landing impact of the crew module was associated with higher seat loads than the arms extended position. With the arms extended and braced on the anterior thighs or knees, loads are transmitted through the extremities to the footrest thereby reducing loading of the vertebral column. Operational use of the arms extended position prior to anticipated vertical impact accelerations may be helpful in reducing the vertebral fracture rate associated with these mechanical force environments.

Adult↗

PubMed1982

Mechanism of vertebral fracture in the F/FB-111 ejection experience.

A review of the accident investigation reports of all non-fatal F/FB-111 ejections which occurred from 19 October 1967 to 26 March 1980 was conducted. The available spinal radiographs of the ejectees were also reviewed. The overall rate of vertebral compression fractures among the survived ejectees in a properly functioning module is 29.5% (23 of 78). The general mechanism of vertebral injury is a combined mechanism involving both axial compression and flexion. There is no evidence to indicate a hyperextension injury mechanism during retraction, nor is there evidence to support the presumed efficacy of the crossed-arms bracing procedure recommended for landing impact in modifying the vertebral injury rate. It appears that a significant reduction in the rate of vertebral fractures among F/FB-111 ejectees will require decreasing the acceleration stresses imposed on the crewmembers during landing impact.

Acceleration↗