460 results match your criteria: "Air Force Institute of Technology[Affiliation]"

Transcatheter aortic valve implantation (TAVI) is common in adults but rare in children and adolescents. Since 2014, our institution has incorporated a transcatheter approach as an option for aortic valve replacement in this population. The purpose of this study was to compare short-term outcomes of TAVI with surgical aortic valve replacement (SAVR).

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Article Synopsis
  • The study analyzed pediatric hospitalizations for COVID-19 during the Delta variant surge from July to August 2021 at six U.S. children's hospitals with 947 total patients, 80.1% of whom had COVID-19.
  • Among these, 37.8% suffered from severe illness, influenced by factors like respiratory syncytial virus (RSV) coinfection and obesity, which significantly increased severity risk in specific age groups.
  • The results highlight the importance of recognizing these risk factors to enhance pediatric care and inform strategies for COVID-19 vaccination and prevention efforts.
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Poverty, food, and nutrition insecurity in sub-Saharan Africa (SSA) have become major concerns in recent times. The effects of climate change, drought, and unpredictable rainfall patterns threaten food production and sustainable agriculture. More so, insurgency, youth restiveness, and politico-economic instability amidst a burgeoning population requiring a sufficient and healthy diet remain front-burner issues in the region.

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Observation of and intention to use new places and changed spaces for physical activity during the COVID-19 pandemic - United States, June 2021.

Prev Med

July 2022

Division of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, GA, United States of America.

The COVID-19 pandemic prompted built environment changes throughout the United States. We assessed the prevalence of new places and changed spaces for physical activity as observed by US adults and their intentions to use them. We used data from SummerStyles, a web-based survey of US adults conducted in June 2021 (n = 4073).

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Guided waves are a potent tool in structural health monitoring, with promising machine learning algorithm applications due to the complexity of their signals. However, these algorithms usually require copious amounts of data to be trained. Collecting the correct amount and distribution of data is costly and time-consuming, and sometimes even borderline impossible due to the necessity of introducing damage to vital machinery to collect signals for various damaged scenarios.

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The development of a machine's condition monitoring system is often a challenging task. This process requires the collection of a sufficiently large dataset on signals from machine operation, context information related to the operation conditions, and the diagnosis experience. The two referred problems are today relatively easy to solve.

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The present study considers the mathematical modelling of unsteady non-Newtonian hydro-magnetic nano-hemodynamics through a rigid cylindrical artery featuring two different stenoses (composite and irregular). The Ostwald-De Waele power-law fluid model is adopted to simulate the non-Newtonian characteristics of blood. Inspired by drug delivery applications for cardiovascular treatments, blood is considered doped with a homogenous suspension of biocompatible nanoparticles.

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Biomechanical and Psychological Predictors of Failure in the Air Force Physical Fitness Test.

Sports (Basel)

April 2022

Data Analytics Certificate Program, Graduate School of Engineering and Management, Air Force Institute of Technology, Wright-Patterson AFB, OH 45433, USA.

Physical fitness is a pillar of U.S. Air Force (USAF) readiness and ensures that Airmen can fulfill their assigned mission and be fit to deploy in any environment.

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Multiphoton Nanosculpting of Optical Resonant and Nonresonant Microsensors on Fiber Tips.

ACS Appl Mater Interfaces

May 2022

Sensors Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States.

This work presents a multiphoton nanosculpting process that is employed to fabricate three-dimensional (3D) mechanically assisted optical resonant and nonresonant microsensors on fiber tips. The resonant microsensor consists of a complex 3D optical cavity design with submicron resolution and advanced micromechanical features including a hinged, multipositional mirror, a 3D spring body to displace this mirror without deforming it, and adhesive-retaining features for sealing the cavity. These features represent a breakthrough in the integration and fabrication capabilities of micro-optomechanical systems.

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Presented are design considerations for a potential detection and measurement technique that could provide operational awareness of high power microwave (HPM) directed energy weapon exposure for force health protection applications, leveraging thermoacoustic (TA) wave generation as the field interaction mechanism. The HPM electromagnetic frequency (EMF) regime, used in applications in both the counter-materiel and non-lethal counter-personnel design space, presents real-time personnel exposure warning challenges due to the potentially wide variation in time and frequency domain characteristics of the incident beam. As with other EM-thermal interactions, the thermoacoustic wave effect provides the potential to determine EM energy and power deposition without the need to measure ambient field intensity values or overload-sensitive EMF survey equipment.

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Considerations for Radio Frequency Fingerprinting across Multiple Frequency Channels.

Sensors (Basel)

March 2022

Department of Electrical and Computer Engineering, Air Force Institute of Technology, Wright-Patterson AFB, OH 45433, USA.

Radio Frequency Fingerprinting (RFF) is often proposed as an authentication mechanism for wireless device security, but application of existing techniques in multi-channel scenarios is limited because prior models were created and evaluated using bursts from a single frequency channel without considering the effects of multi-channel operation. Our research evaluated the multi-channel performance of four single-channel models with increasing complexity, to include a simple discriminant analysis model and three neural networks. Performance characterization using the multi-class Matthews Correlation Coefficient (MCC) revealed that using frequency channels other than those used to train the models can lead to a deterioration in performance from MCC > 0.

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Military aircraft are subjected to variable loads, which are the main cause of initiation and propagation of cracks in the most stressed locations of the airframe. The aim of a Full-Scale Fatigue Test (FSFT) is to represent actual load conditions in such a way that the results obtained are a good representation of the actual loads and may be used as data that give insight into the development of real fatigue damage in critical locations. The FSFT load spectrum is a generalized depiction of the expected service loads and is designed to give an overall good representation of loads exerted on the airframe's structural elements during operation.

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Adsorption of Oxygen to High Entropy Alloy Surfaces for up to 2 ML Coverage Using Density Functional Theory and Monte Carlo Calculations.

Langmuir

March 2022

Department of Engineering Physics, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson Air Force Base, Ohio 45433, United States.

High-entropy alloys (HEAs) manufactured with refractory elements are candidates for high-temperature structural applications. To enhance our understanding of oxidation in these complex systems, the early stages of oxidation on the surface of AlNbTaTiZr were studied using density functional theory and thermodynamic modeling. Surface slabs were generated from bulk configurations sampled from equilibrium using a multicell Monte Carlo method for phase prediction.

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Persistent Room-Temperature Photodarkening in Cu-Doped β-Ga_{2}O_{3}.

Phys Rev Lett

February 2022

Lawrence Livermore National Laboratory, Livermore, California 94551-0808, USA.

β-Ga_{2}O_{3} is an ultrawide band gap semiconductor with emerging applications in power electronics. The introduction of acceptor dopants yields semi-insulating substrates necessary for thin-film devices. In the present work, exposure of Cu-doped β-Ga_{2}O_{3} to UV light >4  eV is shown to cause large, persistent photo-induced darkening at room temperature.

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Coronavirus disease 2019 (COVID-19) has posed severe threats to human safety in the healthcare sector, particularly in residents in long-term care facilities (LTCFs) at a higher risk of morbidity and mortality. This study aims to draw on cumulative prospect theory (CPT) to develop a decision model to explore LTCF administrators' risk perceptions and management decisions toward this pandemic. This study employed the policy Delphi method and survey data to examine managers' perceptions and attitudes and explore the effects of sociodemographic characteristics on healthcare decisions.

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Employees view compulsory citizenship behavior (CCB) as concessionary behavior they undertake because of pressure exerted by their organizations. This study applies affective events theory to CCB-workplace deviance relationships, and impression management theory to CCB-facades of conformity relationships, to posit that employee emotional exhaustion is an essential mediating factor that effectively explains how CCB contributes to workplace deviance and facades of conformity. This study utilizes two mediation models to investigate whether employees' CCBs are positively related to their work deviance and false behavior, and how emotional exhaustion mediates those relationships.

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The aim of this study was to obtain a superhydrophobic coating by modifying anodized aluminum using polydimethylsiloxane (PDMS). In order to obtain a superhydrophobic coating on an aluminum substrate, a multistage treatment was implemented. Specimens of aluminum were treated by abrasive blasting, anodization in sulfuric acid, impregnation by PDMS, rinsing in toluene to remove excess of PDMS, and curing.

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The gut microbiome is impacted by environmental exposures and has been implicated in many physical and mental health conditions, including anxiety disorders, affective disorders, and trauma- and stressor-related disorders such as posttraumatic stress disorder (PTSD). United States (US) military Veterans are a unique population in that their military-related exposures can have consequences for both physical and mental health, but the gut microbiome of this population has been understudied. In this publication, we describe exposures, health conditions, and medication use of Veterans in the US Veteran Microbiome Project (US-VMP) and examine the associations between these characteristics and the gut microbiota.

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This article presents issues concerning the relationship between the degradation of the coating of gas turbine blades and changes in the color of its surface. Conclusions were preceded by the determination of parameters characterizing changes in the technical condition of protective coatings made based on a metallographic examination that defined the morphological modifications of the microstructure of the coating, chemical composition of oxides, and roughness parameters. It has been shown that an increased operating time causes parameters that characterize the condition of the blades to deteriorate significantly.

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This paper is a continuation of research into the possibility of using fuzzy logic to assess the reliability of a selected airborne system. The research objectives include an analysis of statistical data, a reliability analysis in the classical approach, a reliability analysis in the fuzzy set theory approach, and a comparison of the obtained results. The system selected for the investigation was the aircraft gun system.

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Bimodality in reentry latitude predictions for spacecraft in prograde orbits.

J Appl Stat

December 2021

Department of Aeronautics & Astronautics, Air Force Institute of Technology, Wright-Patterson AFB, USA.

Probability distribution functions (PDFs) of atmospheric reentry latitude predictions are shown to be bimodal for spacecraft in low-eccentricity, prograde low Earth orbits at altitudes of 300 km and lower. Using two-line element (TLE) data for initial orbit conditions, coupled with coarse estimates for spacecraft aerodynamic characteristics, parametric simulations produce bimodal distributions that suggest a greater likelihood of reentry near the latitudinal maxima of a given spacecraft's ground track. Various computational measures are used to test for and quantify bimodality in the reentry latitude data sets.

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Assessing the Trustworthiness of Saliency Maps for Localizing Abnormalities in Medical Imaging.

Radiol Artif Intell

November 2021

Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 149 13th St, Boston, MA 02129 (N.A., P.S., K.C., M.A., B.C., K.H., S.G., J.P., M.G., M.D.L., J.K.C.); Department of Computer Science, Shiv Nadar University, Greater Noida, India (N.A.); Department of Operational Sciences, Graduate School of Engineering and Management, Air Force Institute of Technology, Wright-Patterson AFB, Dayton, Ohio (N.G.); and Massachusetts Institute of Technology, Cambridge, Mass (K.C., B.C., K.H., J.P., J.A.).

Purpose: To evaluate the trustworthiness of saliency maps for abnormality localization in medical imaging.

Materials And Methods: Using two large publicly available radiology datasets (Society for Imaging Informatics in Medicine-American College of Radiology Pneumothorax Segmentation dataset and Radiological Society of North America Pneumonia Detection Challenge dataset), the performance of eight commonly used saliency map techniques were quantified in regard to localization utility (segmentation and detection), sensitivity to model weight randomization, repeatability, and reproducibility. Their performances versus baseline methods and localization network architectures were compared, using area under the precision-recall curve (AUPRC) and structural similarity index measure (SSIM) as metrics.

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Objectives: The purpose of this retrospective cohort study was to compare the relative risks (RR) of hearing impairment due to co-exposure of continuous noise, impulse noise, metal ototoxicants, and organic solvent ototoxicants using several pure tone audiometry (PTA) evaluation methods.

Design: Noise and ototoxicant exposure and PTA records were extracted from a DoD longitudinal repository and were analyzed for U.S.

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