Naval Aerospace Medical Research Laboratory

The motion of suspensoid particles relative to that of the solvent resulting from polarization forces produced by an inhomogeneous electric field is defined as ``dielectrophoresis.'' It is analogous to the related phenomenon of electrophoresis, in which motion of suspensoid particles is produced by the action of an electrostatic field on the charged particles. From a consideration of theoretical calculations and from experimental observations it is concluded that the phenomena of ``dielectrophoresis'' and ``dielectro-precipitation'' can be observed under rather ideal conditions, though it is ordinarily often difficult to do so because of the presence of the more easily produced electrophoresis or ion-type migration of charged particles. The usefulness of dielectrophoresis (and/or electrophoresis) for removing suspended solid particles from polymer solutions during analysis is described.

Knowledge of the weight, volume, and center of mass of segments of the human body is of significance to research in such diverse fields as physical education, prosthetics, and space technology.While the specific information needed may vary from one specialty to another, common to all is the objective of understanding more fidly th_ biomechanics of man either as an entity or as a com.ponent of some complex system.The engineer or physicist may test a structure or material until it falls to determine designs and conditions appropriate to the physical characteristics of materia!_.The introduction of man as an integral part of a system, either in a passive or active role, restricts the freedom to test it because of possible injury to the human component.To overcome this restriction, it is common to replace the man with a physical model or, more recently, to use computer simulation.The degree to which a physical or mathematical model can be formulated as an isomorph of the human body thus becomes a crucial factor.This study was designed to supplement existing knowledge of the weight, volume, and location of the center of mass of segments of the human body and to permit their more accurate estimation on the living from anthropometric dimensions.Thirteen male cadavers were each dissected into 14 segments.The weight, volume, and center of mass of each segment were determined, and su/_cient anthropometry of the cadavers was taken to describe the length, circumference, and breadth or depth of each segment.The relationships between the size of the segments and its weight, volume, and the location of its center of mass form the basis for estimating these parameters of living populations." '-,.._ _t,h,l_.

This paper describes some further attempts to identify and measure those parameters in the speech signal that reflect the emotional state of a speaker. High-quality recordings were obtained of professional “method” actors reading the dialogue of a short scenario specifically written to contain various emotional situations. Excerpted portions of the recordings were subjected to both quantitative and qualitative analyses. A comparison was also made of recordings from a real-life situation, in which the emotions of a speaker were clearly defined, with recordings from an actor who simulated the same situation. Anger, fear, and sorrow situations tended to produce characteristic differences in contour of fundamental frequency, average speech spectrum, temporal characteristics, precision of articulation, and waveform regularity of successive glottal pulses. Attributes for a given emotional situation were not always consistent from one speaker to another.

We are developing personal health monitors based on a wireless body area network (BAN) of intelligent sensors. Individual monitors will be integrated into a distributed wireless system for synchronized monitoring of a group of subjects. This system could be used during the selection process and as part of a psychophysiological evaluation of military members undergoing intense training. We use measures of heart-rate variability to quantify stress level prior to and during training as well as to predict stress resistance. This task requires reliable, high-precision instrumentation and synchronized measurements from a group of individuals over prolonged periods (days of training).

Miller, Ronald D. M.D.; Robbins, Thomas O. Cdr, MC, USN; Tonc, Myron J. Lcdr, MC, USNR; Barton, Silas L. HMC, USN Author Information

The remote oculometer is a new instrument for the remote measurement of eye direction and pupil diameter. The electrooptical sensor unit is located several feet from the subject, who is free to move the eye being sensed throughout 1 ft <R xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</R> of space. The video processing is performed in real time by a standard minicomputer. The oculometer processor (minicomputer) provides automatic calibration and linearization to each subject and can, supply the output eye-direction information in the form of either fixation-point coordinates on any specified fixation plane, azimuth and elevation, or direction cosines.The oculometer measures line-of-sight to an accuracy of 1° for eye rotation angles, relative to the sensor unit, of from 0° to + 30° elevation and from -30 ° to + 30 ° azimuth.

&lt;div class="htmlview paragraph"&gt;The response of the human head and neck to impact acceleration has been previously reported for the -X (chest to back) and +Y (right to left) directions. Wide ranges of sled peak acceleration, rate of onset of acceleration and duration of acceleration have been investigated and reported. A major mechanical effect on the dynamic response due to initial position for the -X direction has been reported. The purpose of this study is to report the initial position effect on the human head and neck response for +Y direction experiments.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;Four initial positions of the head relative to the first thoracic vertebral body (T&lt;sub&gt;1&lt;/sub&gt;) have been investigated over a range of sled acceleration peaks from 2 to 7G. The data from six young adult male volunteers representative of a wide range of anthropometry will be presented. There are 18 experiments for each volunteer for a total of 108 experiments.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The effect of initial position on the resulting head angular and linear acceleration, velocity and displacement will be presented. A comparison of the initial position effect for -X and +Y direction experiments will be made. The ability to model the initial position effect will be discussed.&lt;/div&gt;

According to theoretical models of the vestib-ular response system, measures of a few response parameters can be used to predict the dynamic characteristics of vestibular responses of individuals in a variety of situations. Therefore, these measures have theoretical significance as important clinical signs and also as means of predicting individual reactions in aerospace operations. The present paper deals with methods for assessing several of these parameters that relate to semicircular canal function, and in particular it elucidates the development of a method that appears to be practical for the reliable measurement of both nystagmus and sensation parameters. The results of several experiments involved in the development of the method are described.

We compared passive (manual) whole body, and active head oscillation in normal human subjects attempting mentally to influence the vestibulo-ocular reflex (VOR). Our objective was to establish simple procedural guidelines for vestibular test procedures in clinical settings. Using a head-fixed target, both methods of oscillation yielded virtually zero gain. Using an Earth-fixed target, active oscillation gain was unity, while passive gain was slightly less than 1. Using an imagined Earth-fixed target in the dark, both active and passive gains were reduced considerably, but passive gain was reduced more. Using an imagined head-fixed target in the dark, VOR gain was near zero at low frequencies but increased as frequency increased. Again, passive gain was less than active gain. At frequencies above 1 Hz, VOR gain in all conditions approached a value between 0.7 and 0.9. We conclude that active and manual passive rotation are simple and effective methods to test the VOR, but emphasize that visual and mental influences must be carefully controlled.

Drowsiness is one of the cardinal symptoms of motion sickness; therefore, a symptom-complex centering around "drowsiness" has been identified which, for convenience, has been termed the sopite syndrome. Generally, the symptoms characterizing this syndrome are interwoven with other symptoms but under two circumstances the sopite syndrome comprises the main or sole overt manifestation of motion sickness. One circumstance is that in which the intensity of the eliciting stimuli is closely matched to a person's susceptibility, and the sopite syndrome is evoked either before other symptoms of motion sickness appear or in their absence. The second circumstance occurs during prolonged exposure in a motion environment when adaptation results in the disappearance of motion sickness symptoms, except for responses characterizing the sopite syndrome. Typical symptoms of the syndrome are: 1) yawning, 2) drowsiness, 3) disinclination for work, either physical or mental, and 4) lack of participation in group activities. Phenomena derived from an analysis of the symptomatology of the sopite syndrome are qualitatively similar but may differ quantitatively from abstractions derived in other motion sickness responses. One example is the sometimes unique time course of the sopite syndrome. This implies that the immediate eliciting mechanisms not only differ from those involved in evoking other symptoms, but, also, that they must represent first order responses. Diagnosis is difficult unless the syndrome under discussion is kept in mind. Prevention poses a greater problem than treatment.

A procedure has been developed for obtaining reliable measures of sensation associated with semicircular canal stimulation. Theoretically these measures can be used along with measures of nystagmiis to estimate several vestibular response system parameters. In this experiment, responses produced by stimulation of the horizontal semicircular canals are compared with those produced by stimulation of the vertical canals. Group mean estimates of subjective angular displacement obtained from forty US Navy flight students were approximately accurate for stimulation of both horizontal and vertical canals. Significant individual differences were found within the group. From the responses obtained, mean estimates of vestibular system parameters were calculated. The method appears to be a practical means of measuring the K. (θ/Δ) parameter which has not been assessed in the past due to lack of a suitable method.

This article explores some of the engineering approaches to dealing with spatial disorientation (SD) and their drawbacks, looks at nature's approach to spatial orientation, and then presents the Tactical Situation Awareness System (TSAS) as a solution to the SD problem (note: TSAS is a trademark for the service and product of the Naval Aerospace Biomedical Research Laboratory, Pensacola, Florida). The TSAS is an array of tactile stimulators arranged in columns and rows on a garment that a pilot wears on the torso and limbs. This array provides intuitive orientation information to aircrew and operators of remote platforms and is more compatible with a pilot's natural sensory system.

The nuclear magnetic resonance (NMR) spectrum of Na(+) is suitable for qualitative and quantitative analysis of Na(+) in tissues. The width of the NMR spectrum is dependent upon the environment surrounding the individual Na(+) ion. NMR spectra of fresh muscle compared with spectra of the same samples after ashing show that approximately 70% of total muscle Na(+) gives no detectable NMR spectrum. This is probably due to complexation of Na(+) with macromolecules, which causes the NMR spectrum to be broadened beyond detection. A similar effect has been observed when Na(+) interacts with ion exchange resin. NMR also indicates that about 60% of Na(+) of kidney and brain is complexed. Destruction of cell structure of muscle by homogenization little alters the per cent complexing of Na(+). NMR studies show that Na(+) is complexed by actomyosin, which may be the molecular site of complexation of some Na(+) in muscle. The same studies indicate that the solubility of Na(+) in the interstitial water of actomyosin gel is markedly reduced compared with its solubility in liquid water, which suggests that the water in the gel is organized into an icelike state by the nearby actomyosin molecules. If a major fraction of intracellular Na(+) exists in a complexed state, then major revisions in most theoretical treatments of equilibria, diffusion, and transport of cellular Na(+) become appropriate.

The purpose of this study was to determine how chronic exertional fatigue and sleep deprivation coupled with negative energy balance affect thermoregulation during cold exposure. Eight men wearing only shorts and socks sat quietly during 4-h cold air exposure (10 degreesC) immediately after (<2 h, A) they completed 61 days of strenuous military training (energy expenditure approximately 4,150 kcal/day, energy intake approximately 3,300 kcal/day, sleep approximately 4 h/day) and again after short (48 h, SR) and long (109 days, LR) recovery. Body weight decreased 7.4 kg from before training to A, then increased 6.4 kg by SR, with an additional 6.4 kg increase by LR. Body fat averaged 12% during A and SR and increased to 21% during LR. Rectal temperature (Tre) was lower before and during cold air exposure for A than for SR and LR. Tre declined during cold exposure in A and SR but not LR. Mean weighted skin temperature (Tsk) during cold exposure was higher in A and SR than in LR. Metabolic rate increased during all cold exposures, but it was lower during A and LR than SR. The mean body temperature (0.67 Tre + 0.33 Tsk) threshold for increasing metabolism was lower during A than SR and LR. Thus chronic exertional fatigue and sleep loss, combined with underfeeding, reduced tissue insulation and blunted metabolic heat production, which compromised maintenance of body temperature. A short period of rest, sleep, and refeeding restored the thermogenic response to cold, but thermal balance in the cold remained compromised until after several weeks of recovery when tissue insulation had been restored.

Platelet response to hypotonic stress can be used to estimate the 51 Cr recovery in vivo of liquid‐ and freeze‐preserved platelets. This simple in vitro test may prove helpful in determining and controlling the quality of preserved platelets. In our study, the response to hypotonic stress was not related to the 51 Cr T‐1/2 value of the preserved platelets, but was related to the number of irreversibly damaged platelets removed within two hours after transfusion.

The medical and veterinary public-health importance of haematophagous arthropods is immense and continuing to increase because of the emergence of new vector-borne infectious agents and the resurgence of well known ones. Control of blood-feeding arthropods and the pathogens they transmit is compounded by drug, insecticide and acaricide resistance. Novel control strategies are needed. Immunological control is one very promising approach to these problems. In order to develop anti-arthropod vaccines that block pathogen transmission and establishment, the immunological interactions occurring at the interface of the blood-feeding arthropod and host must be characterized. An important component of these interactions is arthropod modulation of the host's innate and acquired, specific immune defences. This review discusses current knowledge regarding the ability of haematophagous arthropods to alter their hosts' immune defences, the impact of those changes on pathogen transmission, the molecular bases for the immunomodulation, and strategies for identification of the molecules in arthropod saliva that are responsible for the immunomodulation.

When a major portion of the intracellular K(+) in frog muscle is reversibly replaced by Na(+), the extra Na(+) gained by the cells does not show the nuclear magnetic resonance signal that free Na(+) does. The data contradict the membrane theory but are in accord with the concept that the bulk of intracellular K(+) is adsorbed.

In Egypt, little is known about the genetic background of Escherichia coli isolates harboring extended-spectrum β-lactamase (ESBL). Five hundred twenty Enterobacteriaceae were prospectively collected (May 2007-August 2008) at the Theodor Bilharz Research Institute (Cairo). Among the collected Enterobacteriaceae, 56% (n=291) were E. coli and 32% (n=165) Klebsiella pneumoniae. A total of 16% (n=3) of all isolates were ESBL, 19% (n=55) of the E. coli and 14% (n=23) of the K. pneumoniae. The proportion of E. coli ESBL producers did not differ significantly between in and outpatients (20% vs. 17%) but was significantly different for non-E. coli ESBL producers (18.5% vs. 1.2%: p=0.0001). The majority of E. coli ESBL producers (75%) was isolated from urine. All the ESBL-producing Enterobacteriaceae available for molecular study (n=74) produced CTX-M-15. Among the CTX-M-15-producing E. coli isolates; 40% belonged to phylogenetic group A, 32% to D, and 26% to B2. ERIC-2 PCR profiles were obtained for all these E. coli isolates and multilocus sequence typing for those belonging to group B2. Genotyping analyses showed strain diversity; however, some clusters had profiles indistinguishable from that of previously published clones. Multilocus sequence typing showed that 75% of E. coli group B2 belonged to clone ST131. This indicates that a new country in Africa is adversely affected by clones of E. coli-producing CTX-M-15.

We propose that learning proper hitting kinematics should be encouraged at a young age during youth baseball because this may help reinforce proper hitting kinematics as a player progresses to higher levels of baseball in their adult years. To enhance our understanding between youth and adult baseball hitting, kinematic and temporal analyses of baseball hitting were evaluated with a high-speed motion analysis system between 12 skilled youth and 12 skilled adult baseball players. There were only a small number of temporal differences between youth and adult hitters, with adult hitters taking significantly greater time than youth hitters during the stride phase and during the swing. Compared with youth hitters, adult hitters a) had significantly greater (p < .01) lead knee flexion when the hands started to move forward; b) flexed the lead knee over a greater range of motion during the transition phase (31 degrees versus 13 degrees); c) extended the lead knee over a greater range of motion during the bat acceleration phase (59 degrees versus 32 degrees); d) maintained a more open pelvis position at lead foot off ground; and e) maintained a more open upper torso position when the hands started to move forward and a more closed upper torso position at bat-ball contact. Moreover, adult hitters had greater peak upper torso angular velocity (857 degrees/s versus 717 degrees/s), peak left elbow extension angular velocity (752 degrees/s versus 598 degrees/s), peak left knee extension angular velocity (386 degrees/s versus 303 degrees/s), and bat linear velocity at bat-ball contact (30 m/s versus 25 m/s). The numerous differences in kinematic and temporal parameters between youth and adult hitters suggest that hitting mechanics are different between these two groups.

Abstract The main feature of this new approach to platelet freezing is a controlled rate of addition and postthaw removal of 5% dimethylsulfoxide (DMSO). When DMSO was removed from fresh nonfrozen platelet concentrates before transfusion, no adverse effect on posttransfusion survival was observed. The 51Cr recovery of autologous fresh platelet concentrates in vivo was 65% ± 5%, while that of autologous platelets previously frozen with DMSO and washed prior to transfusion was 47% ± 3%. The lifespan values were similar for fresh platelets and previously frozen washed platelet concentrates. When approximately 95% of the DMSO was removed from previously frozen washed platelets before transfusion, the 51Cr recovery was about 70% of the value for fresh platelet concentrates, and the lifespan value was similar to that of fresh platelet concentrates. No adverse side effects were observed. The hemostatic effectiveness of these platelets has yet to be studied.