Operations Research, Systems Engineering and Industrial Engineering Commons^™

Trust Development In Swift Starting Action Teams: A Multilevel Framework, Jessica Wildman, Marissa Shuffler, Elizabeth Lazzara, Stephen Fiore, C. Shawn Burke, Eduardo Salas, Sena Garven

US Army Research

Swift starting action teams (STATs) are increasingly prevalent in organizations, and the development of trust is often a critical issue for their effectiveness. However, current theory and research do not provide a clear picture regarding how trust toward the team (i.e., the team as the target) is developed in these settings. The primary contribution of this article is to present a theoretical framework describing how individual-level trust toward one’s team is developed in STAT contexts. This article integrates several existing trust theories into one comprehensive context-specific multilevel theory of how trust develops in STATs from cognitive, affective, behavioral, and contextual …

Grain Refinement Vs. Crystallographic Texture: Mechanical Anisotropy In A Magnesium Alloy, D. C. Foley, M. Al-Maharbi, K. T. Hartwig, I. Karaman, L. J. Kecskes, S. N. Mathaudhu

US Army Research

A magnesium alloy was subjected to severe plastic deformation via an unconventional equal channel angular extrusion route at decreasing temperatures. This method facilitates incremental grain refinement and enhances formability by activating dynamic recrystallization in the initial steps and suppressing deformation twinning. Compression experiments in three orthogonal directions demonstrated high strength levels in the processed sample, up to 350 MPa in yield and 500 MPa in ultimate strengths. Notable flow stress anisotropy is correlated with the processing texture and microstructure.

Mechanical Response Of Pig Skin Under Dynamic Tensile Loading, Jaeyoung Lim, Jihye Hong, Weinong W. Chen, Tusit Weerasooriya

US Army Research

Uniaxial tensile experiments were performed on pig skin to investigate the tensile stressestrain response at both quasi-static and dynamic rates of deformation. A Kolsky tension bar, also called a split Hopkinson tension bar (SHTB), was modified to conduct the dynamic experiments. Semiconductor strain gages were used to measure the low levels of the transmitted signal from pig skin. A pulse shaper technique was used for generating a suitable incident pulse to ensure stress equilibrium and approximate constant strain rate in the specimen of a thin skin sheet wrapped around the ends of the bars for minimizing radial inertia. In order …

Detection Of Six Serotypes Of Botulinum Neurotoxin Using Fluorogenic Reporters, Daniel R. Ruge, F. Mark Dunning, Timothy M. Piazza, Brian E. Molles, Michael Adler, Füsûn N. Zeytin, Ward C. Tucker

US Army Research

Methods that do not require animal sacrifice to detect botulinum neurotoxins (BoNTs) are critical for BoNT antagonist discovery and the advancement of quantitative assays for biodefense and pharmaceutical applications. Here we describe the development and optimization of fluorogenic reporters that detect the proteolytic activity of BoNT/A, B, D, E, F, and G serotypes in real time with femtomolar to picomolar sensitivity. Notably, the reporters can detect femtomolar concentrations of BoNT/A in 4 h and BoNT/E in 20 h, sensitivity that equals that of animal-based methods. The reporters can be used to determine the specific activity of BoNT preparations with intra- …

An Alternative Approach To Integrating Plasticity Relations, Richard Becker

US Army Research

A new plasticity integration algorithm is proposed based upon observations from the closed form integration of a generalized quadratic yield function over a single time step. The key to the approach is specification of the normal to the plastic flow potential as a function of the current state and strain increment. This uniquely defines the direction of the stress tensor for a convex, non-faceted flow potential. The stress magnitude and plastic strain increment are computed to satisfy the yield function. A non-quadratic, isotropic, associative flow model is coded to demonstrate accuracy and time step convergence following a step change in …

Protective Immunity To Pre-Erythrocytic Stage Malaria, Robert J. Schwenk, Thomas L. Richie

US Army Research

The development of a vaccine against malaria is a major research priority given the burden of disease, death and economic loss inflicted upon the tropical world by this parasite. Despite decades of effort, however, a vaccine remains elusive. The best candidate is a subunit vaccine termed RTS,S but this provides only partial protection against clinical disease. This review examines what is known about protective immunity against pre-erythrocytic stage malaria by considering the humoral and T cell-mediated immune responses that are induced by attenuated sporozoites and by the RTS,S vaccine. On the basis of these observations a set of research priorities …

Digital Holographic Imaging Of Aerosol Particles In Flight, Matthew J. Berg, Gorden Videen

US Army Research

This work describes the design and application of an apparatus to image aerosol
particles using digital holography in a flow-through, contact-free manner. Particles in an aerosol stream are illuminated by a triggered, pulsed laser and the pattern produced by the interference of this light with that scattered by the particles is recorded by a digital camera. The recorded pattern constitutes a digital hologram from which an image of the particles is computationally reconstructed using a fast Fourier transform. This imaging is validated using a cluster of ragweed pollen particles. Examples involving mineral-dust aerosols demonstrate the technique’s in situ imaging capability …

A New Explanation Of The Extinction Paradox, Matthew J. Berg, C. M. Sorensen, A. Chakrabarti

US Army Research

This work presents a new explanation for the extinction paradox and shows that the canonical explanations are incorrect. This paradox refers to the large size limit of a particle’s extinction cross section. It is called a paradox because the geometrical optics approximation, which should be valid in this limit, predicts a cross section that is half of the true value. The new explanation is achieved by formulating the scattered wave in terms of an integral over the particle’s surface where the seemingly unrelated Ewald–Oseen theorem appears in the formulation. By expressing the cross section in terms of this surface integral, …

Application Of Hyperspectral Vegetation Indices To Detect Variations In High Leaf Area Index Temperate Shrub Thicket Canopies, Steven T. Brantley, Julie C. Zinnert, Donald R. Young

US Army Research

Accurate measurement of leaf area index (LAI), an important characteristic of plant canopies directly linked to primary production, is essential for monitoring changes in ecosystem C stocks and other ecosystem level fluxes. Direct measurement of LAI is labor intensive, impractical at large scales and does not capture seasonal or annual variations in canopy biomass. The need to monitor canopy related fluxes across landscapes makes remote sensing an attractive technique for estimating LAI. Many vegetation indices, such as Normalized Difference Vegetation Index (NDVI), tend to saturate at LAI levels >4 although tropical and temperate forested ecosystems often exceed that threshold. Using …

A Phase Field Model Of Deformation Twinning: Nonlinear Theory And Numerical Simulations, J. D. Clayton, J. Knap

US Army Research

A continuum phase field theory and corresponding numerical solution methods are developed to describe deformation twinning in crystalline solids. An order parameter is associated with the magnitude of twinning shear, i.e., the lattice transformation associated with twinning. The general theory addresses the following physics: large deformations, nonlinear anisotropic elastic behavior, and anisotropic phase boundary energy. The theory is applied towards prediction of equilibrium phenomena in the athermal and non-dissipative limit, whereby equilibrium configurations of an externally stressed crystal are obtained via incremental minimization of a free energy functional. Outcomes of such calculations are elastic fields (e.g., displacement, strain, stress, and …

Purification Of A Recombinant Heavy Chain Fragment C Vaccine Candidate Against Botulinum Serotype C Neurotoxin [Rbontc(HC)] Expressed In Pichia Pastoris, Michael P. Dux, Jicai Huang, Rick Barent, Mehmet Inan, S. Todd Swanson, Jayanta Sinha, John T. Ross, Leonard A. Smith, Theresa J. Smith, Ian Henderson, Michael M. Meagher

US Army Research

A purification process for the manufacture of a recombinant C-terminus heavy chain fragment from botulinum neurotoxin serotype C [rBoNTC(H_c)], a potential vaccine candidate, has been defined and successfully scaled-up. The rBoNTC(H_c) was produced intracellularly in Pichia pastoris X-33 using a three step fermentation process, i.e., glycerol batch phase, a glycerol fed-batch phase to achieve high cell densities, followed by a methanol induction phase. The rBoNTC(H_c) was captured from the soluble protein fraction of cell lysate using hydrophobic charge induction chromatography (HCIC; MEP HyperCel™), and then further purified using a CM 650M ion exchange chromatography …

Clostridium Difficile Infections In Patients With Severe Burns, Scott J. Crabtree, Janelle L. Robertson, Kevin K. Chung, Evan M. Renz, Steven E. Wolf, Duane R. Hospenthal, Clinton K. Murray

US Army Research

With improved survival in burn patients, Clostridium difficile infection (CDI) remains a significant potential complication. The incidence of, risk factors for, and outcomes of CDI in severely burned patients are poorly studied and remain unclear. This study involves retrospective case control and cohort studies using electronic medical records from February 1, 2002 to January 31, 2009 at the US Department of Defense’s only burn unit. Demographic, risk factor, and outcome data were collected for all C. difficile toxin positive patients in the burn, medical, and surgical intensive care units and the hospital’s step down unit along with an additional analysis …

Relationship Of Surface Changes To Metal Leaching From Tungsten Composite Shot Exposed To Three Different Soil Types, Deborah Felt, Steven Larson, Chris Griggs, Catherine Nestler, Michelle Wynter

US Army Research

Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten–nickel–iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite …

Determination Of Threshold Adverse Effect Doses Of Percutaneous Vx Exposure In African Green Monkeys, Raymond F. Genovese, Bernard J. Benton, John L. Oubre, Christopher E. Byers, E. Michael Jakubowski, Robert J. Mioduszewski, Timothy J. Settle, Thomas J. Steinbach

US Army Research

Percutaneous exposure to the chemical warfare nerve agent VX was evaluated in African green monkeys (n = 9). Doses of VX (7.5–100 μg/kg) were applied to the skin for 60 min and residual agent was quantified (before decontamination) to estimate the absorbed dose. Monkeys were evaluated for the presence or absence of clinical signs of toxicity and blood was sampled periodically (30 min–12 weeks) following exposure to measure the degree of circulating acetylcholinesterase (AChE) inhibition. Monkeys were also evaluated for behavioral changes fromVXexposure using a serial probe recognition (SPR) task. The lowest observable adverse effect level (LOAEL) for the production …

Investigations Of Transcript Expression In Fathead Minnow (Pimephales Promelas) Brain Tissue Reveal Toxicological Impacts Of Rdx Exposure, Kurt A. Gust, Mitchell S. Wilbanks, Xin Guan, Mehdi Pirooznia, Tanwir Habib, Leslie Yoo, Henri Wintz, Chris D. Vulpe, Edward J. Perkins

US Army Research

Production, usage and disposal of the munitions constituent (MC) cyclotrimethylenetrinitramine (RDX) has led to environmental releases on military facilities. The chemical attributes of RDX are conducive for leaching to surface water which may put aquatic organisms at risk of exposure. Because RDX has been observed to cause aberrant neuromuscular effects across a wide range of animal phyla, we assessed the effects of RDX on central nervous system (CNS) functions in the representative aquatic ecotoxicological model species, fathead minnow (Pimephales promelas). We developed a fathead minnow brain-tissue cDNA library enriched for transcripts differentially expressed in response to RDX and …

Nanoindentation Characterization Of Deformation And Failure Of Aluminum Oxynitride, J. J. Guo, K. Wang, T. Fujita, J. W. Mccauley, J. P. Singh, M. W. Chen

US Army Research

A systematic study of the mechanical deformation and failure of transparent ceramic aluminum oxynitride (AlON) has been conducted using a depth-sensitive nanoindentation technique combined with transmission electron microscopy (TEM) and Raman spectroscopy. Although discrete displacement bursts appear in the load–depth profiles at high applied forces, a detectable high-pressure phase transition has not been found by means of micro-Raman spectroscopy and TEM. Instead, a high density of dissociated (1 1 0) dislocations can be observed underneath the nanoindenters, suggesting that extensive plastic deformation takes place in the brittle ceramic at high contact pressures. Moreover, nanoindentation-induced micro-cracks oriented along well-defined crystallographic planes …

Eating Rate During A Fixed-Portion Meal Does Not Affect Postprandial Appetite And Gut Peptides Or Energy Intake During A Subsequent Meal, J. Phillip Karl, Andrew J. Young, Scott J. Montain

US Army Research

Eating rate has recently been shown to influence energy intake and appetite during an ad libitummeal, and alter postprandial secretion of glucagon-like peptide-1 (GLP-1) and peptide-YY (PYY) following a fixed-portionmeal. Whether these effects influence satiety, as measured by energy intake at the subsequent meal, is unclear. We manipulated eating rate during a fixed-portion meal in order to examine how eating behavior and associated periprandial and postprandial responses of putative endocrine mediators of appetite would affect energy intake at the following meal in fifteen non-obese (BMI ≥ 25 kg/m²) and ten obese (BMI ≥ 30 kg/m²) healthy adult men and …

Fatigue-Induced Grain Coarsening In Nanocrystalline Platinum Films, Roi A. Meirom, Daan Hein Alsem, Amber L. Romasco, Trevor Clark, Ronald G. Polcawich, Jeffrey S. Pulskamp, Madan Dubey, Robert O. Ritchie, Christopher L. Muhlstein

US Army Research

Mechanisms to explain the unique mechanical behavior of nanograined metals focus primarily on grain and grain boundary mobility. In most nanograined metal materials systems (both pure and alloyed) it has not been possible to decouple these time- and cycle-dependent contributions. In contrast, the 460 nm thick, (1 1 1) textured, nanograined platinum thin films evaluated in this work have robust grain morphologies that allow us to uniquely identify the fatigue damage accumulation processes. Unlike other reports of face-centered cubic metal behavior, the platinum films exhibited a particularly limited range of fatigue crack growth (<3 MPa √m) with extremely large (~10.5) power law exponents typically associated with fatigue of structural ceramics and ordered intermetallics. Transmission electron microscopy and fatigue crack growth data suggest that the crack growth mechanism appears to be intrinsic in origin and dislocation mediated.

Effects Of Gage Length, Loading Rates, And Damage On The Strength Of Ppta Fibers, Jaeyoung Lim, James Q. Zheng, Karl Masters, Weinong W. Chen

US Army Research

Axial tension and transverse compression experiments on single fibers were performed to investigate the mechanical behavior of three high-performance fibers (Kevlar ®, Kevlar ® 129, and Twaron ®) with diameters in the order of 9-12 μm. The single fibers were manufactured from 1998 through 2008. A miniaturized tensile Kolsky bar was used to determine the tensile response of PPTA single fibers at a high strain rate. Gage length and strain rate were found to have minimum effects on the tensile strength of PPTA single fibers. Manufacturing time over a decade was found to have negligible effects on the tensile strength …

Thermoreversible And Remendable Glass–Polymer Interface For Fiber-Reinforced Composites, Amy M. Peterson, Robert E. Jensen, Giuseppe R. Palmese

US Army Research

Adhesion of the reinforcement to the polymer matrix is essential for load transfer from the polymer matrix to the reinforcement material in fiber-reinforced composites. The reversible Diels–Alder reaction between a furan-functionalized epoxy-amine thermosetting matrix with a maleimide-functionalized glass fiber was used to impart remendability at the polymer–glass interface for potential application in glass fiber-reinforced composites. At room temperature the Diels–Alder adduct is formed spontaneously and above 90 °C the adduct breaks apart to reform the original furan and maleimide moieties. Healing of the interface was investigated with single fiber microdroplet pull-out testing. Following complete failure of this interface, significant healing …

Micro-Cracks Informed Damage Models For Brittle Solids, Xiaodan Ren, Jiun-Shyan Chen, Jie Li, T. R. Slawson, M. J. Roth

US Army Research

A class of micro-cracks informed damage models for describing the softening behavior of brittle solids is proposed, in which damage evolution is treated as a consequence of micro-crack propagation. The homogenized stress–strain relation in the cracked microscopic cell defines the degradation tensor, which can be obtained by the equivalence between the averaged strain energy of the microscopic cell and the strain energy density of the homogenized material. This energy equivalence relationship serves as an energy bridging vehicle between the damaged continuum and the cracked microstructure. Several damage evolution equations are obtained by this energy bridging method. The size effect of …

Prophylaxis With Human Serum Butyrylcholinesterase Protects Guinea Pigs Exposed To Multiple Lethal Doses Of Soman Or Vx, Ashima Saxena, Wei Sun, James M. Fedorko, Irwin Koplovitz, Bhupendra P. Doctor

US Army Research

Human serum butyrylcholinesterase (Hu BChE) is currently under advanced development as a bioscavenger for the prophylaxis of organophosphorus (OP) nerve agent toxicity in humans. It is estimated that a dose of 200 mg will be required to protect a human against 2 × LD₅₀ of soman. To provide data for initiating an investigational new drug application for the use of this enzyme as a bioscavenger in humans, we purified enzyme from Cohn fraction IV-4 paste and initiated safety and efficacy evaluations in mice, guinea pigs, and non-human primates. In mice, we demonstrated that a single dose of enzyme that …

Antimicrobial Decapeptide Ksl-W Attenuates Candida Albicans Virulence By Modulating Its Effects On Toll-Like Receptor, Human Β-Defensin, And Cytokine Expression By Engineered Human Oral Mucosa, A. Semlali, K. P. Leung, S. Curt, M. Rouabhia

US Army Research

We investigated the toxicity of synthetic antimicrobial decapeptide KSL-W on normal human gingival epithelial cell cultures, its effect on Candida albicans adhesion and growth, and the activation of epithelial cell innate immunity. Our results indicate that KSL-W had no toxic effect on cell adhesion or growth, suggesting its safe use with human cells. Pre-treating C. albicans with KSL-W attenuated the yeast’s virulence as demonstrated by its reduced adhesion and growth on engineered human oral mucosa epithelium and the subsequent decreased expression of some innate defense molecules by targeted epithelial cells. Indeed, the expression of Toll-like receptors and human β-defensins was …

Safety And Protective Efficacy Of Ina-Inactivated Venezuelan Equine Encephalitis Virus: Implication In Vaccine Development, Anuj Sharma, Paridhi Gupta, Pamela J. Glass, Michael D. Parker, Radha K. Maheshwari

US Army Research

We have previously shown that a hydrophobic alkylating compound, 1,5-iodonaphthyl-azide (INA) can efficiently inactivate the virulent strain of Venezuelan equine encephalitis virus (VEEV), V3000 in vitro. In this study, we have evaluated the safety of INA-inactivated V3000 and V3526 and the protective efficacy of INA-inactivated V3000. INA-inactivated V3000 and V3526 did not cause disease in suckling mice. RNA isolated from the INA-inactivated V3000 and V3526 was also not infectious. Immunization of adult mice with INA-inactivated V3000 induced an anti-VEEV antibody response and protected mice from virulent VEEV challenge. The protective efficacy of INA-inactivated V3000 increased with the use of adjuvants. …

Protective Efficacy Of Catalytic Bioscavenger, Paraoxonase 1 Against Sarin And Soman Exposure In Guinea Pigs, Manojkumar Valiyaveettil, Yonas Alamneh, Peter Rezk, Lionel Biggemann, Michael W. Perkins, Alfred M. Sciuto, Bhupendra P. Doctor, Madhusoodana P. Nambiar

US Army Research

Human paraoxonase 1 (PON1) has been portrayed as a catalytic bioscavenger which can hydrolyze large amounts of chemical warfare nerve agents (CWNAs) and organophosphate (OP) pesticides compared to the stoichiometric bioscavengers such as butyrylcholinesterase. We evaluated the protective efficacy of purified human and rabbit serum PON1 against nerve agents sarin and soman in guinea pigs. Catalytically active PON1 purified from human and rabbit serum was intravenously injected to guinea pigs, which were 30 min later exposed to 1.2 × LCt₅₀ sarin or soman using a microinstillation inhalation exposure technology. Pre-treatment with 5 units of purified human and rabbit serum …

Dislocation–Twin Interactions In Nanocrystalline Fcc Metals, Y. T. Zhu, X. L. Wu, X. Z. Liao, J. Narayan, L. J. Keckés, S. N. Mathaudhu

US Army Research

Dislocation interaction with and accumulation at twin boundaries have been reported to significantly improve the strength and ductility of nanostructured face-centered cubic (fcc) metals and alloys. Here we systematically describe plausible dislocation interactions at twin boundaries. Depending on the characteristics of the dislocations and the driving stress, possible dislocation reactions at twin boundaries include cross-slip into the twinning plane to cause twin growth or de-twinning, formation of a sessile stair-rod dislocation at the twin boundary, and transmission across the twin boundary. The energy barriers for these dislocation reactions are described and compared.

Microstructure And Mechanical Properties At Different Length Scales And Strain Rates Of Nanocrystalline Tantalum Produced By High-Pressure Torsion, Q. Wei, Z. L. Pan, X. L. Wu, B. E. Schuster, L. J. Kecdkes, R. Z. Valiev

US Army Research

Fully dense, nanocrystalline tantalum (average grain size as small as ~40 nm) has been processed for the first time by high-pressure torsion. High-resolution transmission electron microscopy reveals non-equilibrium grain boundaries and grains decorated with high-density dislocations. Microhardness measurements and instrumented nanoindentation experiments indicate that the mechanical property is quite uniform except for the central area of the disks. Nanoindentation experiments at different strain rates suggest that the strain rate sensitivity of nanocrystalline tantalum is increased compared to the coarse- and ultrafine-grained counterparts and is accompanied by an activation energy of the order of a few ~b3 (b is the magnitude …

Recombinant Paraoxonase 1 Protects Against Sarin And Soman Toxicity Following Microinstillation Inhalation Exposure In Guinea Pigs, Manojkumar Valiyaveettil, Yonas Alamneh, Peter Rezk, Michael W. Perkins, Alfred M. Sciuto, Bhupendra P. Doctor, Madhusoodana P. Nambiar

US Army Research

To explore the efficacy of paraoxonase 1 (PON1) as a catalytic bioscavenger, we evaluated human recombinant PON1 (rePON1) expressed in Trichoplusia ni larvae against sarin and soman toxicity using microinstillation inhalation exposure in guinea pigs. Animals were pretreated intravenously with catalytically active rePON1, followed by exposure to 1.2 X LCt₅₀ sarin or soman. Administration of 5 units of rePON1 showed mild increase in the blood activity of the enzyme after 30 min, but protected the animals with a significant increase in survival rate along with minimal signs of nerve agent toxicity. Recombinant PON1 pretreated animals exposed to sarin or …

Activity Of Topical Antimicrobial Agents Against Multidrug-Resistant Bacteria Recovered From Burn Patients, Jessie S. Glasser, Charles H. Guymon, Katrin Mende, Steven E. Wolf, Duane R. Hospenthal, Clinton K. Murray

US Army Research

Background:

Topical antimicrobials are employed for prophylaxis and treatment of burn
wound infections despite no established susceptibility breakpoints, which are becoming vital in an era of multidrug-resistant (MDR) bacteria. We compared two methods of determining topical antimicrobial susceptibilities.

Methods:

Isolates of Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), extended spectrum beta-lactamase (ESBL) producing Klebsiella pneumoniae, and Acinetobacter baumanii-calcoaceticus (ABC) from burn patients were tested using broth microdilution and agar well diffusion to determine minimum inhibitory concentrations (MICs) and zones of inhibition (ZI). Isolates had systemic antibiotic resistance and clonality determined. MDR included resistance to antibiotics in three or more …

Socio-Demographic And Drug Use Factors Associated With Hiv-1 Recombinants And Dual Infections In Northern Thai Drug Users: Associations Of Risk With Genetic Complexity, G. H. Kijak, C. Beyrer, S. Tovanabutra, T. Sripaipan, V. Suriyanon, N. Moqueet, E. Sanders-Buell, P. Saokhieo, U. Timpan, J. Jittiwutikarn, M. L. Robb, D. L. Birx, D. D. Celentano, F. E. Mccutchan

US Army Research

Background:

Dual infection with diverse HIV strains can foster the emergence of recombinants. The resulting increase in viral genetic diversity is a major challenge for vaccine development HIV treatment. In this study we aim to investigate the socio demographic factors associated with an increasing level of genetic diversity among HIV strains in a population of drug-users in Northern Thailand.

Methods:

From 1999 through 2000, 2231 volunteers were enrolled in the Opiate- Users Research in Chiang Mai, Thailand. HIV subtype analysis was conducted among those HIV-1 seropositive (n = 347) using a multi-region hybridization assay. Social and demographic variables were assessed …