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Tufts J.B.,University of Connecticut | Chen S.,University of Connecticut | Marshall L.,Naval Submarine Medical Research Laboratory
Journal of the Acoustical Society of America | Year: 2013

Custom-molded earplugs (CMEPs) whose canal segments extend beyond the second bend of the ear canal can provide excellent attenuation but can sometimes be uncomfortable. Attenuation was measured for CMEPs whose canal segments were shortened in 2-mm increments. The within-subjects design permitted illustration of the form of the function relating attenuation to canal segment length for individuals. Reduction of attenuation due to canal segment shortening was generally more pronounced for frequencies ≤1000 Hz. Some regions of the canal segments were more critical than others in maintaining attenuation. The relationship between comfort and canal segment length was not straightforward. © 2013 U.S. Government.

Tufts J.B.,University of Connecticut | Weathersby P.K.,Naval Submarine Medical Research Laboratory | Rodriguez F.A.,University of Connecticut
Scandinavian Journal of Work, Environment and Health | Year: 2010

Objective: The purpose of this paper is to demonstrate the feasibility and utility of developing economic cost models for noise-induced hearing loss (NIHL). First, we outline an economic model of NIHL for a population of US Navy sailors with an "industrial"-type noise exposure. Next, we describe the effect on NIHL-related cost of varying the two central model inputs - the noise-exposure level and the duration of exposure. Such an analysis can help prioritize promising areas, to which limited resources to reduce NIHL-related costs should be devoted. Methods: NIHL-related costs borne by the US government were computed on a yearly basis using a finite element approach that took into account varying levels of susceptibility to NIHL. Predicted hearing thresholds for the population were computed with ANSI S3.44-1996 and then used as the basis for the calculation of NIHL-related costs. Annual and cumulative costs were tracked. Noise-exposure level and duration were systematically varied to determine their effects on the expected lifetime NIHL-related cost of a specific US Navy sailor population. Results: Our nominal noise-exposure case [93 dB(A) for six years] yielded a total expected lifetime cost of US$13 472 per sailor, with plausible lower and upper bounds of US$2500 and US$26 000. Starting with the nominal case, a decrease of 50% in exposure level or duration would yield cost savings of approximately 23% and 19%, respectively. We concluded that a reduction in noise level would be more somewhat more cost-effective than the same percentage reduction in years of exposure. Conclusion: Our economic cost model can be used to estimate the changes in NIHL-related costs that would result from changes in noise-exposure level and/or duration for a single military population. Although the model is limited at present, suggestions are provided for adapting it to civilian populations.

Luria S.M.,Naval Submarine Medical Research Laboratory | Strauss M.S.,University of Illinois at Urbana - Champaign
Perception | Year: 2013

Eye movements were recorded while subjects viewed ordinary portraits and photographic negatives of those portraits. Under both conditions they first studied sixteen portraits and then tried to decide which of forty-eight portraits they had just seen. They made more errors of recognition while viewing negatives, and their fixation patterns were significantly altered: there was a decrease in the percentage of fixations directed to the eyes, nose, and mouth, and an increase for such details as the ears, cheeks, chin, cap, and necktie. There was also a decrease in the ratio of fixations to the most fixated detail compared to the least fixated detail. © 1974 a Pion publication printed in Great Britain.

Marshall L.,Naval Submarine Medical Research Laboratory | Lapsley Miller J.A.,Naval Submarine Medical Research Laboratory | Guinan J.J.,Massachusetts Eye and Ear Infirmary | Shera C.A.,Massachusetts Eye and Ear Infirmary | And 4 more authors.
Journal of the Acoustical Society of America | Year: 2014

Otoacoustic emission (OAE) tests of the medial-olivocochlear reflex (MOCR) in humans were assessed for viability as clinical assays. Two reflection-source OAEs [TEOAEs: transient-evoked otoacoustic emissions evoked by a 47 dB sound pressure level (SPL) chirp; and discrete-tone SFOAEs: stimulus-frequency otoacoustic emissions evoked by 40 dB SPL tones, and assessed with a 60 dB SPL suppressor] were compared in 27 normal-hearing adults. The MOCR elicitor was a 60 dB SPL contralateral broadband noise. An estimate of MOCR strength, MOCR%, was defined as the vector difference between OAEs measured with and without the elicitor, normalized by OAE magnitude (without elicitor). An MOCR was reliably detected in most ears. Within subjects, MOCR strength was correlated across frequency bands and across OAE type. The ratio of across-subject variability to within-subject variability ranged from 2 to 15, with wideband TEOAEs and averaged SFOAEs giving the highest ratios. MOCR strength in individual ears was reliably classified into low, normal, and high groups. SFOAEs using 1.5 to 2 kHz tones and TEOAEs in the 0.5 to 2.5 kHz band gave the best statistical results. TEOAEs had more clinical advantages. Both assays could be made faster for clinical applications, such as screening for individual susceptibility to acoustic trauma in a hearing-conservation program. © 2014 U.S. Government.

Gasier H.G.,Naval Submarine Medical Research Laboratory | Fluckey J.D.,Texas A&M University | Previs S.F.,Case Western Reserve University
Nutrition and Metabolism | Year: 2010

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). © 2010 Gasier et al; licensee BioMed Central Ltd.

Gasier H.G.,Center for Hyperbaric Medicine and Environmental Physiology | Hughes L.M.,Naval Submarine Medical Research Laboratory | Young C.R.,Naval Submarine Medical Research Laboratory | Richardson A.M.,Baystate Childrens Hospital
PLoS ONE | Year: 2015

Background Little is known of the diagnostic accuracy of BMI in classifying obesity in active duty military personnel and those that previously served. Thus, the primary objectives were to determine the relationship between lean and fat mass, and body fat percentage (BF%) with BMI, and assess the agreement between BMI and BF% in defining obesity. Methods Body composition was measured by dual-energy X-ray absorptiometry in 462 males (20-91 years old) who currently or previously served in the U.S. Navy. A BMI of 30 kg/m2 and a BF% 25% were used for obesity classification. Results The mean BMI (± SD) and BF% were 28.8 ± 4.1 and 28.9 ± 6.6%, respectively, with BF% increasing with age. Lean mass, fat mass, and BF% were significantly correlated with BMI for all age groups. The exact agreement of obesity defined by BMI and BF% was fair (61%), however, 38% were misclassified by a BMI cut-off of 30 when obesity was defined by BF%. Conclusions From this data we determined that there is a good correlation between body composition and BMI, and fair agreement between BMI and BF% in classifying obesity in a group of current and former U.S. Navy service members. However, as observed in the general population, a significant proportion of individuals with excess fat are misclassified by BMI cutoffs. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Gasier H.,Naval Submarine Medical Research Laboratory | Olson C.,Salus Education LLC
Journal of Exercise Physiology Online | Year: 2010

Carbohydrate-protein (CHO-PRO) beverages have been reported to improve endurance performance; however, no studies have been conducted on elite military combatants in a field setting in a fed state. Thus, the primary objective of this study was to evaluate the effects of a CHO-PRO supplement on physical performance and mood in U.S. Air Force Pararescue indoctrination trainees. Eight, healthy U.S. Air Force Pararescue indoctrination trainees completed a double-blind, randomized crossover study. Following a morning meal (592 kcal), subjects completed a 2000 m swim, physically demanding water activities, calisthenics (push-ups, pull-ups, curl-ups and flutter-kicks), a 6.4 km run, and a 400 m exhaustive run. Supplements (600 ml x 5 doses) were provided throughout the study and consisted of a placebo (PLA), an 8.9% carbohydrate solution (CHO), and a 7.22% carbohydrate/1.81% protein solution (CHO-PRO). Times (minutes and seconds) and repetitions were used to assess physical performance, and subjective mood states were determined using the Profile of Mood States Questionnaire (POMS). No differences were observed between the CHO-PRO, CHO, and PLA groups on any of the physical performance measures or mood states. These results suggest that, in the fed state, a CHO-PRO beverage does not enhance physical performance or mood during a series of physically demanding activities lasting < 1 h in duration in U.S. Air Force Pararescue indoctrination trainees.

Lee B.C.,Naval Submarine School | Young C.R.,Naval Submarine Medical Research Laboratory
Undersea and Hyperbaric Medicine | Year: 2015

This case report presents a military diver who became dysphoric and lost consciousness during a routine surface- supplied dive. The patient regained consciousness spontaneously, but the physical exam was notable for bilateral ophthalmoplegia. Full eye movement was regained during hyperbaric oxygen (HBO2) therapy, and the patient subsequently made a full recovery. Equipment and dive profile analysis led to the conclusion of hypercapnia and arterial gas embolism as the probable causes of the diver's symptoms. This is a unique case of isolated bilateral ophthalmoplegia presenting in a diving injury. Copyright © 2015 Undersea & Hyperbaric Medical Society, Inc.

Reini S.A.,Naval Submarine Medical Research Laboratory
Aviation Space and Environmental Medicine | Year: 2010

Cortisol is a stress-response hormone that is important for survivability in fight or flight situations. Hypercortisolism is a state of chronically elevated cortisol levels due to a failure to return to, or maintain baseline levels. It is a condition that is often undiagnosed and can aid in the development of many physiological and psychological health problems. Some of the health ailments associated with hypercortisolism include metabolic syndrome, decreases in bone mineral density, and depression. Chronic stress and sleep deprivation are two common causes of hypercortisolism, both areas of concern within the submarine community. This review discusses the etiology of hypercortisolism and the likelihood of submariner vulnerability to the condition along with health problems associated with it. Lastly, strategies to prevent chronic elevation of cortisol and mitigate the potential health risks associated with the condition are covered. Copyright © by the Aerospace Medical Association, Alexandria, VA.

O'Donnell S.W.,Naval Submarine School | Horn W.G.,Naval Submarine Medical Research Laboratory
Undersea and Hyperbaric Medicine | Year: 2014

The U.S. Navy reinstituted pressurized submarine escape training (PSET) for submarine sailors in 2009 after a nearly 30-year absence. This training addresses escape from a disabled submarine at depth with the use of the Beaufort, Ltd. Mk 10 Submarine Escape and Immersion Equipment (SEIE) suit. Training is classified as "high-risk" due to previous U.S. and foreign navy experience with trainingassociated morbidity and mortality, particularly from diving-related illness. To reduce risk, medical screening procedures are performed. During the first 39 months of training, 7,025 students screened for PSET with 32% completing all phases, including two pressurized ascents. The most common reason for screening disqualification was presence of upper respiratory congestion. During training, middle ear barotrauma was responsible for 53% of attrition, primarily during the test of pressure. Copyright © 2014 Undersea & Hyperbaric Medical Society, Inc.

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