Naval Submarine Medical Research Laboratory

Although substantial literatures attest to the psychosocial impact of individuals' physical attractiveness and the centrality of physical self-concept, or body image, to global self-concept, little research has examined the relationship of these two variables to depression. Accordingly, in the present study, 224 college men and women completed alfective and cognitive measures of body image, the Center for Epidemiologlcal Studies-Depression scale (CES-D), and a single, self-labeling of depression item. Each subject was videotaped, and objective raters reliably evaluated a static, full-body pose of each subject on physical attractiveness. The subjects were classified as depressed (n = 35) or nondepressed (n = 42) on the basis of the conjunctive criteria of self-labeling and extreme groups on the CESD. As hypothesized, the multivariate and univariate analyses of variance indicated that depressed subjects were less satisfied with their bodies and saw themselves as less physically attractive than was reported by nondepressed subjects. These groups did not differ, however, with respect to observer-rated physical attractiveness. Support was obtained for Beck's (1973, 1976) cognitive hypothesis that depressed persons negatively distort their body images. However, the results also indicated substantial positive distortion among nondepressed subjects.

Immersive technologies, such as virtual and augmented reality, initially failed to live up to expectations, but have improved greatly, with many new head-worn displays and associated applications being released over the past few years. Unfortunately, ‘cybersickness’ remains as a common user problem that must be overcome if mass adoption is to be realized. This article evaluates the state of research on this problem, identifies challenges that must be addressed, and formulates an updated cybersickness research and development (R&D) agenda. The new agenda recommends prioritizing creation of powerful, lightweight, and untethered head-worn displays, reduction of visual latencies, standardization of symptom and aftereffect measurement, development of improved countermeasures, and improved understanding of the magnitude of the problem and its implications for job performance. Some of these priorities are unresolved problems from the original agenda which should get increased attention now that immersive technologies are proliferating widely. If the resulting R&D agenda is carefully executed, it should render cybersickness a challenge of the past and accelerate mass adoption of immersive technologies to enhance training, performance, and recreation.

Available measurements by different investigators on the relationship between pupil diameter and luminance of large adapting fields were compiled and weighted for the number of observers used. The equation for the curve that best fits eight sets of data is logd=0.8558−0.000401 (logB+8.1)3, where d is the diameter of the natural pupil in millimeters and B is the luminance of the adapting field in millilamberts. This is the best estimate that can be made to date of the pupil size—luminance relationship. To make the data of more general use they were corrected for the Stiles-Crawford effect and expressed so that retinal illuminance, adjusted for average pupil size, may be obtained directly from knowledge of the luminance of the stimulus field. The expression for this is logE(trolands)=logB+1.8614–0.000986 (logB+6.5)3, where E is the retinal illuminance in trolands and B is luminance in millilamberts. It is unfortunate that no extensive measurements have been made in this important area.

Context-specific personality items provide respondents with a common frame of reference unlike more traditional, noncontextual personality items. The common frame of reference standardizes item interpretation and has been shown to reduce measurement error while increasing validity in comparison to noncontextual items (M. J. Schmit, A. M. Ryan. S. L. Stierwalt. & S. L. Powell, 1995). Although the frame-of-reference effect on personality scales scores has been well investigated (e.g., M. J. Schmit et al., 1995), the ability of this innovation to obtain incremental validity above and beyond the well-established, noncontextual personality scale scores has yet to be examined. The current study replicates and extends work by M. J. Schmit et al. (1995) to determine the incremental validity of the frame-of-reference effect. The results indicate that context-specific personality items do indeed obtain incremental validity above and beyond both noncontextual items and cognitive ability, and in spite of socially desirable responding induced by applicant instructions. The implications of these findings for personnel selection are discussed.

BACKGROUND: Linezolid has been associated with anemia and thrombocytopenia. Mechanisms for neither have been elucidated. OBJECTIVE: To propose mechanisms for linezolid-induced anemia and thrombocytopenia. CASE SUMMARY: A 78-year-old white woman with Staphylococcus epidermidis endocarditis was treated with linezolid after developing resistance to multiple antibiotic regimens. After 7 days of linezolid therapy, she developed thrombocytopenia, while an anemia present since admission remained unchanged. A bone marrow biopsy was performed, primarily looking for a mechanism for the thrombocytopenia. Histopathology revealed adequate megakaryocytes, ringed sideroblasts, and vacuolated pronormoblasts. A course of immune globulin (IVIG) was administered, with slowing in the rate of decline in platelets. She died 24 hours after her last dose of IVIG of congestive heart failure. DISCUSSION: The presence of ringed sideroblasts and vacuolated pronormoblasts suggests that linezolid-induced anemia is secondary to a chloramphenicol-like suppression of erythropoiesis. The presence of adequate, normal-appearing megakaryocytes suggests immune-mediated thrombocytopenia, not marrow suppression. Although the response to IVIG is difficult to interpret because of the patient's death, there was a slowing in the rate of decline of the platelet count, further supporting immune-mediated thrombocytopenia. An objective causality assessment indicated that the adverse drug event was probably due to linezolid. CONCLUSIONS: There appear to be 2 distinct mechanisms for linezolid-induced cytopenias. While anemia is reversible and manageable with transfusions, thrombocytopenia can be a treatment-limiting toxicity. The ability to treat through an immune-mediated cytopenia with IVIG may be beneficial for critically ill patients with few therapeutic options.

The osteogenic potential of decalcified freeze-dried bone allografts in the treatment of human periodontal osseous defects was evaluated over a 6 month period. Cortical bone, obtained under sterile conditions from a human donor within 24 hours after death, was decalcified, freeze-dried and ground to a particle size of 250 to 500 microns. Twenty-seven osseous defects with one-, two- and wide three-wall morphology were treated. Clinical measurements were made with a stent and a calibrated periodontal probe before surgery, at the time of surgery, and at re-entry. The combined mean osseous regeneration for all defects was 2.4 mm. This represented a 65% mean bone-fill of the original defect. The findings demonstrate that decalcified freeze-dried bone allograft has potential as an osseous grafting material in periodontal therapy.

A multiclinic, collaborative study has been designed to assess the natural progression and efficacy of treatment of Duchenne muscular dystrophy. This article describes the protocol for the evaluation technique and the method used to establish within (intraobserver) and between (interobserver) reliability of the protocol evaluation procedures. Standardized patient evaluations were used, and consistency of evaluation was monitored by a computer. The reliability of the measures was analyzed 1) within observers by comparing the results of each of the first three tests done by each evaluator for all patients and 2) between observers by comparing, at multicenter group meetings, the results of each of the four evaluators' tests of the same patient. We have demonstrated reliability for an evaluation method that will provide an objective foundation on which to claim a drug or therapeutic procedure does or does not have an effect in treating Duchenne muscular dystrophy.

The respiratory response to CO2 was studied in 65 subjects exposed to various CO2 concentrations (1.5, 3.3, 5.4 and 7.5% CO2) for 15 minutes followed by a recovery period of equal length. The well known large individual differences in the response to CO2 were related to the basic respiratory pattern of the individual on air. On the basis of differences in the ventilatory response to 5.4% and 7.5% CO2, subjects were classified in a high and low ventilation group. The latter showed, during normal breathing of air, a significantly lower respiratory rate and larger tidal volume as well as a higher alveolar CO2 level. In 31 subjects whose lung volumes were measured, those with a low ventilatory response to CO2 had a larger tidal volume, inspiratory reserve and vital capacity, while the expiratory reserve did not differ. Under proper experimental conditions, the individual respiratory response to CO2, as well as the basic respiratory pattern on air remain fairly constant. Subjects with a high sensitivity to CO2 were found to have also a high sensitivity to low O2 and vice versa. The difference in the ventilatory response to CO2 appears to be correlated with differences in the adrenal sympathetic response to CO2. The group differences are also reflected in symptoms incident to inhalation of 7.5% CO2 as noted in 42 subjects. Possible utilization of the respiratory response to CO2 as a physiological selection test for underwater swimmers and aviators is discussed. Submitted on November 12, 1957

Resilience has been recognized as an important phenomenon for understanding how individuals overcome difficult situations. However, it is not only individuals who face difficulties; it is not uncommon for teams to experience adversity. When they do, they must be able to overcome these challenges without performance decrements.This manuscript represents a theoretical model that might be helpful in conceptualizing this important construct. Specifically, it describes team resilience as a second-order emergent state. We also include research propositions that follow from the model.

Unprotected dogs decompressed from 100- or 200-foot equivalent depth (water) with trachea closed developed pulmonary interstitial emphysema and air embolism, probably via the pulmonary veins, when the intratracheal pressure reached a critical level of approximately 80 mm Hg. The lungs became markedly distended by entrapped air expanding as the ambient pressure was reduced. The systemic aortic pressure fell in consequence of compression of postarterial vessels in the lungs, indicated by a higher gradient between pulmonary arterial and left atrial pressures. Interstitial emphysema and air embolism could be prevented by the application of thoraco-abdominal binders, despite a rise in intratracheal pressure to levels of 180 mm Hg or more. The effects of the binders were: a) to prevent overdistention of the lung as indicated by the small difference between the intratracheal and intrapleural pressures; b) to keep at a lower level the pressure gradient between the respiratory passages and the pulmonary veins-left atrium; c) to maintain the systemic aortic pressure, in part, at least, in consequence of a low transcapillary pressure gradient. These observations suggest the possible utility of compressive garments of the ‘G-suit’ type in escape procedures. The critical factor for the development of pulmonary interstitial emphysema and air embolism appears to be not an absolute level of the intratracheal pressure, but rather a transpulmonic pressure in excess of 60–70 mm Hg or a transatrial pressure in excess of 55–65 mm Hg. Submitted on November 12, 1957

Twenty-one subjects were exposed to 1.5% CO 2 in 21% O 2 for 42 days with pre- and postexposure periods on air for 9 days. Respiratory minute volume (Ve) and alveolar pCO 2 were increased throughout the exposure to CO 2 . After transition to air Ve decreased, while pCO 2 remained elevated for 9 days. CO 2 retention with uncompensated respiratory acidosis lasted for 23 days. CO 2 excretion was increased during the 9-day recovery period indicating release of CO 2 from the CO 2 stores. Oxygen consumption did not change significantly during the experiment. Respiratory acclimatization to CO 2 involved a continuous increase in tidal volume while the respiratory rate declined slowly after an initial increase. Changes in respiratory pattern were associated with an increase in physiological and anatomical dead space. A significant increase in the arterial-alveolar pCO 2 and alveolar-arterial pO 2 gradient indicated the development of an alveolar dead space. The ventilatory response to 5% CO 2 was markedly reduced at the end of CO 2 exposure. chronic CO 2 exposure; chronic hypercapnia; chronic respiratory acidosis Submitted on August 31, 1961

In a longitudinal study with 338 volunteers, audiometric thresholds and otoacoustic emissions were measured before and after 6 months of noise exposure on an aircraft carrier. While the average amplitudes of the otoacoustic emissions decreased significantly, the average audiometric thresholds did not change. Furthermore, there were no significant correlations between changes in audiometric thresholds and changes in otoacoustic emissions. Changes in transient-evoked otoacoustic emissions and distortion-product otoacoustic emissions were moderately correlated. Eighteen ears acquired permanent audiometric threshold shifts. Only one-third of those ears showed significant otoacoustic emission shifts that mirrored their permanent threshold shifts. A Bayesian analysis indicated that permanent threshold shift status following a deployment was predicted by baseline low-level or absent otoacoustic emissions. The best predictor was transient-evoked otoacoustic emission amplitude in the 4-kHz half-octave frequency band, with risk increasing more than sixfold from approximately 3% to 20% as the emission amplitude decreased. It is possible that the otoacoustic emissions indicated noise-induced changes in the inner ear, undetected by audiometric tests. Otoacoustic emissions may therefore be a diagnostic predictor for noise-induced-hearing-loss risk.

We present diagnostic criteria for motion sickness, visually induced motion sickness (VIMS), motion sickness disorder (MSD), and VIMS disorder (VIMSD) to be included in the International Classification of Vestibular Disorders. Motion sickness and VIMS are normal physiological responses that can be elicited in almost all people, but susceptibility and severity can be high enough for the response to be considered a disorder in some cases. This report provides guidelines for evaluating signs and symptoms caused by physical motion or visual motion and for diagnosing an individual as having a response that is severe enough to constitute a disorder. The diagnostic criteria for motion sickness and VIMS include adverse reactions elicited during exposure to physical motion or visual motion leading to observable signs or symptoms of greater than minimal severity in the following domains: nausea and/or gastrointestinal disturbance, thermoregulatory disruption, alterations in arousal, dizziness and/or vertigo, headache and/or ocular strain. These signs and/or symptoms occur during the motion exposure, build as the exposure is prolonged, and eventually stop after the motion ends. Motion sickness disorder and VIMSD are diagnosed when recurrent episodes of motion sickness or VIMS are reliably triggered by the same or similar stimuli, severity does not significantly decrease after repeated exposure, and signs/symptoms lead to activity modification, avoidance behavior, or aversive emotional responses. Motion sickness/MSD and VIMS/VIMSD can occur separately or together. Severity of symptoms in reaction to physical motion or visual motion stimuli varies widely and can change within an individual due to aging, adaptation, and comorbid disorders. We discuss the main methods for measuring motion sickness symptoms, the situations conducive to motion sickness and VIMS, and the individual traits associated with increased susceptibility. These additional considerations will improve diagnosis by fostering accurate measurement and understanding of the situational and personal factors associated with MSD and VIMSD.

We have developed hydrophobic electrodes that provide all morphological waveforms without distortion of an ECG signal for both dry and water-immersed conditions. Our electrode is comprised of a mixture of carbon black powder (CB) and polydimethylsiloxane (PDMS). For feasibility testing of the CB/PDMS electrodes, various tests were performed. One of the tests included evaluation of the electrode-to-skin contact impedance for different diameters, thicknesses, and different pressure levels. As expected, the larger the diameter of the electrodes, the lower the impedance and the difference between the large sized CB/PDMS and the similarly-sized Ag/AgCl hydrogel electrodes was at most 200 kΩ, in favor of the latter. Performance comparison of CB/PDMS electrodes to Ag/AgCl hydrogel electrodes was carried out in three different scenarios: a dry surface, water immersion, and postwater immersion conditions. In the dry condition, no statistical differences were found for both the temporal and spectral indices of the heart rate variability analysis between the CB/PDMS and Ag/AgCl hydrogel (p > 0.05) electrodes. During water immersion, there was significant ECG amplitude reduction with CB/PDMS electrodes when compared to wet Ag/AgCl electrodes kept dry by their waterproof adhesive tape, but the reduction was not severe enough to obscure the readability of the recordings, and all morphological waveforms of the ECG signal were discernible even when motion artifacts were introduced. When water did not penetrate tape-wrapped Ag/AgCl electrodes, high fidelity ECG signals were observed. However, when water penetrated the Ag/AgCl electrodes, the signal quality degraded to the point where ECG morphological waveforms were not discernible.

Skeletal muscle protein synthesis has generally been determined by the precursor:product labeling approach using labeled amino acids (e.g., [13C]leucine or [13C]-, [15N]-, or [2H]phenylalanine) as the tracers. Although reliable for determining rates of protein synthesis, this methodological approach requires experiments to be conducted in a controlled environment, and as a result, has limited our understanding of muscle protein renewal under free-living conditions over extended periods of time (i.e., integrative/cumulative assessments). An alternative tracer, 2H2O, has been successfully used to measure rates of muscle protein synthesis in mice, rats, fish and humans. Moreover, perturbations such as feeding and exercise have been included in these measurements without exclusion of common environmental and biological factors. In this review, we discuss the principle behind using 2H2O to measure muscle protein synthesis and highlight recent investigations that have examined the effects of feeding and exercise. The framework provided in this review should assist muscle biologists in designing experiments that advance our understanding of conditions in which anabolism is altered (e.g., exercise, feeding, growth, debilitating and metabolic pathologies).

A recent large civilian randomized controlled trial on the use of tranexamic acid (TXA) for trauma reported important survival benefits. Subsequently, successful use of TXA for combat casualties in Afghanistan was also reported. As a result of these promising studies, there has been growing interest in the use of TXA for trauma. Potential adverse effects of TXA have also been reported. A US Department of Defense committee conducted a review and assessment of knowledge gaps and research requirements regarding the use of TXA for the treatment of casualties that have experienced traumatic hemorrhage. We present identified knowledge gaps and associated research priorities. We believe that important knowledge gaps exist and that a targeted, prioritized research effort will contribute to the refinement of practice guidelines over time.

Abstract : The accuracy of absolute distance estimation based on monocular motion parallax was determined both before and after specific training. With the usual distance information eliminated, subjects either held their heads stationary or rhythmically rotated their heads from side to side while judging the distance of stimuli placed 4-15 ft. away. Before training, head movement produced more accurate judgments than head fixed. After only 10 training trials, accurate judgments based on motion parallax were obtained. Results with a textured background were better than results with a white background only when the subjects were not given any direct information about motion parallax. Good results were also obtained for motion parallax relative to a near reference object (2.5 ft. away). The results indicate that motion parallax can be useful for absolute distance estimation, and they suggest that motion parallax would be useful in the underwater environment, where the usual sources of distance information are absent or distorted.

Grisel's syndrome is a rare but well-documented clinical entity. It is a nontraumatic, fixed rotary subluxation of C1 on C2 (atlantoaxial). Although first described in 1830, the exact mechanism of Grisel's syndrome remains unclear. We present a postoperative case of Grisel's syndrome and an extensive literature review, and we propose a mechanism for its pathogenesis. In addition, we propose a treatment algorithm for Grisel's syndrome.

Freeze-dried crushed cortical bone allografts were implanted into widemouthed three-wall, two-wall, one-wall, combination, and furcation defects. One hundred eighty-nine sites were reentered in 97 patients and of these 60% had osseous regeneration of greater than 50%. A total of 231 sites were evaluated for pocket elimination, of which 63% demonstrated greater than 50% pocket reduction. This study presented additional evidence indicating that freeze-dried bone allografts have definite potential as grafting material in certain periodontal osseous defects. Information from additional cases is being tabulated as it becomes available and will supplement the current data.

Non-linear transient-evoked otoacoustic emissions (TEOAEs) at 74dB pSPL, distortion-product otoacoustic emissions (DPOAEs) at 65/45dB SPL and pure-tone audiometry were used to detect noise-induced, inner car changes in a longitudinal study. Repeated-measures ANOVAs were made on the Noise (n=69) and Quiet (n=42) groups. The Noise group's hearing thresholds increased by 1.2 dB and DPOAE amplitude decreased by -0.9 dB. For both groups, TEOAE amplitude decreased by approximately -0.6 dB. Eight of 12 ears with permanent threshold shift (PTS) and 10 of 13 ears with temporary threshold shift (TTS) showed TEOAE decrements or low baseline TEOAE amplitudes. Fewer TTS and PTS ears also showed DPOAE decrements, and there was never a DPOAE decrement without a corresponding TEOAE decrement or low TEOAE baseline. Some TTS ears showed permanent emission decrements. Although otoacoustic emissions show promise in detecting noise-induced inner ear changes, it is premature to use them in hearing conservation programs.