Wright-Patterson AFB, OH, United States
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Sloan C.,Brigham Young University | Heaton M.,Brigham Young University | Kang S.,Brigham Young University | Berrett C.,Brigham Young University | And 7 more authors.
Health and Place | Year: 2017

Infant bronchiolitis is primarily due to infection by respiratory syncytial virus (RSV), which is highly seasonal. The goal of the study is to understand how circulation of RSV is impacted by fluctuations in temperature and humidity in order to inform prevention efforts. Using data from the Military Health System (MHS) Data Repository (MDR), we calculated rates of infant bronchiolitis for the contiguous US from July 2004 to June 2013. Monthly temperature and relative humidity were extracted from the National Climate Data Center. Using a spatiotemporal generalized linear model for binomial data, we estimated bronchiolitis rates and the effects of temperature and relative humidity while allowing them to vary over location and time. Our results indicate a seasonal pattern that begins in the Southeast during November or December, then spreading in a Northwest direction. The relationships of temperature and humidity were spatially heterogeneous, and we find that climate can partially account for early onset or longer epidemic duration. Small changes in climate may be associated with larger fluctuations in epidemic duration. © 2017 Elsevier Ltd


Centeno J.A.,Joint Pathology Center | Rogers D.A.,Joint Pathology Center | van der Voet G.B.,Joint Pathology Center | Fornero E.,Joint Pathology Center | And 7 more authors.
International Journal of Environmental Research and Public Health | Year: 2014

Background: The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD) directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries. Objectives: The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material. Methods: We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU), tungsten (W), lead (Pb), and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF), scanning electron microscopy (SEM), laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS), and confocal laser Raman microspectroscopy (CLRM). Quantitative chemical analysis of both fragments and available tissues was conducted employing ICP-MS. Results: Over 800 fragments have been characterized and included as part of the Joint Pathology Center Embedded Fragment Registry. Most fragments were obtained from penetrating wounds sustained to the extremities, particularly soft tissue injuries. The majority of the fragments were primarily composed of a single metal such as iron, copper, or aluminum with traces of antimony, titanium, uranium, and lead. One case demonstrated tungsten in both the fragment and the connected tissue, together with lead. Capsular tissue and fragments from a case from the 1991 Kuwait conflict showed evidence of uranium that was further characterized by uranium isotopic ratios analysis to contain depleted uranium. Conclusions: The present study provides a systematic approach for obtaining a full chemical characterization of retained embedded fragments. Given the vast number of combat casualties with retained fragments, it is expected that fragment analysis will have significant implications for the optimal short and long-term care of wounded service members. © 2014 by the authors; licensee MDPI, Basel, Switzerland.


PubMed | Naval Medical Research Unit Dayton, Oak Ridge Institute for Science and Education and Air Force Research Lab
Type: Journal Article | Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience | Year: 2015

Investigations into the use of transcranial direct current stimulation (tDCS) in relieving symptoms of neurological disorders and enhancing cognitive or motor performance have exhibited promising results. However, the mechanisms by which tDCS effects brain function remain under scrutiny. We have demonstrated that in vivo tDCS in rats produced a lasting effect on hippocampal synaptic plasticity, as measured using extracellular recordings. Ex vivo preparations of hippocampal slices from rats that have been subjected to tDCS of 0.10 or 0.25 mA for 30 min followed by 30 min of recovery time displayed a robust twofold enhancement in long-term potentiation (LTP) induction accompanied by a 30% increase in paired-pulse facilitation (PPF). The magnitude of the LTP effect was greater with 0.25 mA compared with 0.10 mA stimulations, suggesting a dose-dependent relationship between tDCS intensity and its effect on synaptic plasticity. To test the persistence of these observed effects, animals were stimulated in vivo for 30 min at 0.25 mA and then allowed to return to their home cage for 24 h. Observation of the enhanced LTP induction, but not the enhanced PPF, continued 24 h after completion of 0.25 mA of tDCS. Addition of the NMDA blocker AP-5 abolished LTP in both control and stimulated rats but maintained the PPF enhancement in stimulated rats. The observation of enhanced LTP and PPF after tDCS demonstrates that non-invasive electrical stimulation is capable of modifying synaptic plasticity.Researchers have used brain stimulation such as transcranial direct current stimulation on human subjects to alleviate symptoms of neurological disorders and enhance their performance. Here, using rats, we have investigated the potential mechanisms of how in vivo brain stimulation can produce such effect. We recorded directly on viable brain slices from rats after brain stimulation to detect lasting changes in pattern of neuronal activity. Our results showed that 30 min of brain stimulation in rats induced a robust enhancement in synaptic plasticity, a neuronal process critical for learning and memory. Understanding such molecular effects will lead to a better understanding of the mechanisms by which brain stimulation produces its effects on cognition and performance.


PubMed | University of Idaho and U.S. Navy
Type: | Journal: Chemistry (Weinheim an der Bergstrasse, Germany) | Year: 2016

A fused-ring conjugated energetic molecule, 4-amino-3,7-dinitro-[1,2,4]triazolo[5,1-c] [1,2,4]triazine (TTX), has been synthesized in good yield in a two-step process starting from the known 5-amino-3-nitro-1H-1,2,4-triazole (ANTA). Characterization of TTX shows that it possesses energetic properties approaching those of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), but with a higher thermal stability and lower sensitivity towards impact and friction.


Chandler J.F.,Naval Medical Research Unit Dayton | Arnold R.D.,Naval Medical Research Unit Dayton | Phillips J.B.,Naval Medical Research Unit Dayton | Turnmire A.E.,Naval Medical Research Unit Dayton
Aviation Space and Environmental Medicine | Year: 2013

Background: Fatigue's negative impact on safety represents one of the top threats tomilitary transportation. Biomathematical models have been developed to predict the response to fatigue; however, current models do not take into account stable individual differences in fatigue susceptibility. Readiness Screening Tools (RSTs) can capture individual differences in fatigue response, but cannot predict performance longterm. The objectiveofthis study was to combine an existing biomathematical model of fatigue with existing RST-derived measures to determine current ability to predict individual differences in fatigueresponse. We hypothesized that the predictive ability of the biomathematical model could be significantly improved by incorporating cognitive and oculometric measures showntobe sensitive to individual differences in fatigue response. Methods: Data on multiple cognitive and oculometric measures were collected at rested baseline and then every 3 hacross 25 h of continual wakefulness. Results characterized actual fatigued performance at the group and individual levels. Actual performance was compared to predicted performancedecrements over the same time period. The unique variance explained by each approach was then combined to determine if RST-derived individual difference measures added significantpredictive power to the model. Results: Addition of individual- difference sensitive RST measures to an existing fatigue model significantly increased the amount of variance in performance explained by the model from 13.8 to 35.7%. Discussion: Simply leveraging RSTs'ability to capture individual differences in fatigue susceptibility can substantially improve biomathematical prediction of fatigued performance. © by the Aerospace Medical Association, Alexandria, VA.


Hartzler B.M.,Naval Medical Research Unit Dayton
Accident Analysis and Prevention | Year: 2014

The detrimental effects of fatigue in aviation are well established, as evidenced by both the number of fatigue-related mishaps and numerous studies which have found that most pilots experience a deterioration in cognitive performance as well as increased stress during the course of a flight. Further, due to the nature of the average pilot's work schedule, with frequent changes in duty schedule, early morning starts, and extended duty periods, fatigue may be impossible to avoid. Thus, it is critical that fatigue countermeasures be available which can help to combat the often overwhelming effects of sleep loss or sleep disruption. While stimulants such as caffeine are typically effective at maintaining alertness and performance, such countermeasures do nothing to address the actual source of fatigue - insufficient sleep. Consequently, strategic naps are considered an efficacious means of maintaining performance while also reducing the individual's sleep debt. These types of naps have been advocated for pilots in particular, as opportunities to sleep either in the designated rest facilities or on the flight deck may be beneficial in reducing both the performance and alertness impairments associated with fatigue, as well as the subjective feelings of sleepiness. Evidence suggests that strategic naps can reduce subjective feelings of fatigue and improve performance and alertness. Despite some contraindications to implementing strategic naps while on duty, such as sleep inertia experienced upon awakening, both researchers and pilots agree that the benefits associated with these naps far outweigh the potential risks. This article is a literature review detailing both the health and safety concerns of fatigue among commercial pilots as well as benefits and risks associated with strategic napping to alleviate this fatigue.


Lynn Caldwell J.,Naval Medical Research Unit Dayton | Chandler J.F.,Naval Medical Research Unit Dayton | Hartzler B.M.,Naval Medical Research Unit Dayton
Journal of Medical Sciences | Year: 2012

Despite knowledge gained through decades of research, fatigue due to insufficient sleep remains an ingrained part of military and commercial aviation and represents a major threat to the health, safety, and effectiveness of aircrew. Long duty periods, high workloads, circadian disruptions, and insufficient recovery time between flights ensure sleepiness is a continued problem for both civilian and military aircrew. The majority of our knowledge concerning the effects of fatigue is gained from acute, total sleep deprivation laboratory-based studies which describe results in terms of the average individual's response to total sleep loss. However, in operational environments, limited sleep over many days, termed chronic sleep restriction, is more commonly experienced than acute, total sleep deprivation, casting some doubt on the operational applicability of many previous studies. Furthermore, recent studies have identified strong individual differences in fatigue resistance. Our understanding of the effects of chronic sleep restriction and the individual differences in response to fatigue is currently limited in comparison to that of acute sleep deprivation. In this review, we identify the substantial progress made over the last 2 decades in closing these gaps. Advances in understanding the effects of chronic sleep restriction, the recovery timeline associated with sleep loss, and individual responses to sleep loss represent a critical step in the improvement of current, and the formulation of future, countermeasures in the aviation environment. Adjustments to duty rotation and crew scheduling, refinement of biomathematical models of fatigue, and application of currently available countermeasures are the most immediate of these improvements. © 2012 JMS.


PubMed | Naval Medical Research Unit Dayton
Type: | Journal: Accident; analysis and prevention | Year: 2013

The detrimental effects of fatigue in aviation are well established, as evidenced by both the number of fatigue-related mishaps and numerous studies which have found that most pilots experience a deterioration in cognitive performance as well as increased stress during the course of a flight. Further, due to the nature of the average pilots work schedule, with frequent changes in duty schedule, early morning starts, and extended duty periods, fatigue may be impossible to avoid. Thus, it is critical that fatigue countermeasures be available which can help to combat the often overwhelming effects of sleep loss or sleep disruption. While stimulants such as caffeine are typically effective at maintaining alertness and performance, such countermeasures do nothing to address the actual source of fatigue - insufficient sleep. Consequently, strategic naps are considered an efficacious means of maintaining performance while also reducing the individuals sleep debt. These types of naps have been advocated for pilots in particular, as opportunities to sleep either in the designated rest facilities or on the flight deck may be beneficial in reducing both the performance and alertness impairments associated with fatigue, as well as the subjective feelings of sleepiness. Evidence suggests that strategic naps can reduce subjective feelings of fatigue and improve performance and alertness. Despite some contraindications to implementing strategic naps while on duty, such as sleep inertia experienced upon awakening, both researchers and pilots agree that the benefits associated with these naps far outweigh the potential risks. This article is a literature review detailing both the health and safety concerns of fatigue among commercial pilots as well as benefits and risks associated with strategic napping to alleviate this fatigue.


PubMed | Naval Medical Research Unit Dayton
Type: Journal Article | Journal: Aviation, space, and environmental medicine | Year: 2013

Fatigues negative impact on safety represents one of the top threats to military transportation. Biomathematical models have been developed to predict the response to fatigue; however, current models do not take into account stable individual differences in fatigue susceptibility. Readiness Screening Tools (RSTs) can capture individual differences in fatigue response, but cannot predict performance long-term. The objective of this study was to combine an existing biomathematical model of fatigue with existing RST-derived measures to determine current ability to predict individual differences in fatigue response. We hypothesized that the predictive ability of the biomathematical model could be significantly improved by incorporating cognitive and oculometric measures shown to be sensitive to individual differences in fatigue response.Data on multiple cognitive and oculometric measures were collected at rested baseline and then every 3 h across 25 h of continual wakefulness. Results characterized actual fatigued performance at the group and individual levels. Actual performance was compared to predicted performance decrements over the same time period. The unique variance explained by each approach was then combined to determine if RST-derived individual difference measures added significant predictive power to the model.Addition of individual-difference sensitive RST measures to an existing fatigue model significantly increased the amount of variance in performance explained by the model from 13.8 to 35.7%.Simply leveraging RSTs ability to capture individual differences in fatigue susceptibility can substantially improve biomathematical prediction of fatigued performance.


PubMed | Naval Medical Research Unit Dayton
Type: Comparative Study | Journal: Aviation, space, and environmental medicine | Year: 2012

Effective hypoxia-related mishap prevention relies upon aircrew rapid recognition of hypoxia symptoms. The objectives of this experiment were twofold: to compare the effectiveness of a forehead-mounted reflectance oximeter and finger-mounted pulse oximeter for application in a hypoxia early warning detection system, and to determine whether the forehead-mounted sensor could be placed within an aviation helmet.Subjects donned an aviation flight mask and were instrumented with a forehead reflectance oximeter, a finger pulse oximeter, a blood pressure cuff, and a skin temperature sensor. Following instrumentation, subjects breathed ambient air for 10 min through the Reduced Oxygen Breathing Device (ROBD) to allow for acclimation. The baseline period was followed by one of two counterbalanced ascent profiles used to model rapid exposures to altitude. Data were collected at 1 Hz from both sensors for the duration of the protocol.Analyses indicated an exceptionally strong agreement between the forehead and finger sensors at all ranges of desaturation. The sensitivity data revealed that the forehead sensor was significantly faster when responding to rapid changes in SpO2 than the finger. The sensor was successfully integrated inside the helmet; however, once donned by the subject, there was considerable artifact due to pressure fluctuations.While these data may seem to suggest that the forehead sensor is accurate and sensitive to altitude induced changes in SpO2, major drawbacks exist for the technology utilized in the current study. Significant improvements aimed at diminishing noise, curbing motion artifact, and improving reliability are required to reduce errant measurements.

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