Showing papers by "United States Department of the Army published in 1994"
TL;DR: Simulations on synthetic images indicate that the new algorithm performs better and requires much less computation than MAP estimation using simulated annealing, and is found to improve classification accuracy when applied to the segmentation of multispectral remotely sensed images with ground truth data.
Abstract: Many approaches to Bayesian image segmentation have used maximum a posteriori (MAP) estimation in conjunction with Markov random fields (MRF). Although this approach performs well, it has a number of disadvantages. In particular, exact MAP estimates cannot be computed, approximate MAP estimates are computationally expensive to compute, and unsupervised parameter estimation of the MRF is difficult. The authors propose a new approach to Bayesian image segmentation that directly addresses these problems. The new method replaces the MRF model with a novel multiscale random field (MSRF) and replaces the MAP estimator with a sequential MAP (SMAP) estimator derived from a novel estimation criteria. Together, the proposed estimator and model result in a segmentation algorithm that is not iterative and can be computed in time proportional to MN where M is the number of classes and N is the number of pixels. The also develop a computationally efficient method for unsupervised estimation of model parameters. Simulations on synthetic images indicate that the new algorithm performs better and requires much less computation than MAP estimation using simulated annealing. The algorithm is also found to improve classification accuracy when applied to the segmentation of multispectral remotely sensed images with ground truth data. >
687 citations
TL;DR: In this paper, the authors numerically investigate nonlinear propagation of ultrashort pulses in a one-dimensional photonic band gap structure and find that nonlinear effects cause a dynamical shift in the location of the band gap.
Abstract: We numerically investigate nonlinear propagation of ultrashort pulses in a one-dimensional photonic band gap structure. We find that, near the band edge, nonlinear effects cause a dynamical shift in the location of the band gap. We demonstrate that this nonlinear mechanism can induce intensity-dependent pulse transmission and reflections. In addition, pulse reshaping and pulse generation is observed. This phenomenon has important new applications in both optical limiting and optical switching.
534 citations
TL;DR: To optimize the filter's performance, the usual hard constraints on the outputs in the synthetic discriminant function formulation are removed, and the resulting filters exhibit superior distortion tolerance while retaining the attractive features of their predecessors.
Abstract: A mathematical analysis of the distortion tolerance in correlation filters is presented. A good measure for distortion performance is shown to be a generalization of the minimum average correlation energy criterion. To optimize the filter's performance, we remove the usual hard constraints on the outputs in the synthetic discriminant function formulation. The resulting filters exhibit superior distortion tolerance while retaining the attractive features of their predecessors such as the minimum average correlation energy filter and the minimum variance synthetic discriminant function filter. The proposed theory also unifies several existing approaches and examines the relationship between different formulations. The proposed filter design algorithm requires only simple statistical parameters and the inversion of diagonal matrices, which makes it attractive from a computational standpoint. Several properties of these filters are discussed with illustrative examples.
394 citations
TL;DR: The results indicated that PfHRP-2 antigen was not detectable in blood 6 days after initiation of curative chemotherapy, and suggest that such circulating antigens rarely lead to false-positive tests.
313 citations
TL;DR: The linking-field neural network model was introduced to explain the experimentally observed synchronous activity among neural assemblies in the cat cortex induced by feature-dependent visual activity and gives a basic new function: grouping by similarity.
Abstract: The linking-field neural network model of Eckhorn et al. [Neural Comput. 2, 293-307 (1990)] was introduced to explain the experimentally observed synchronous activity among neural assemblies in the cat cortex induced by feature-dependent visual activity. The model produces synchronous bursts of pulses from neurons with similar activity, effectively grouping them by phase and pulse frequency. It gives a basic new function: grouping by similarity. The synchronous bursts are obtained in the limit of strong linking strengths. The linking-field model in the limit of moderate-to-weak linking characterized by few if any multiple bursts is investigated. In this limit dynamic, locally periodic traveling waves exist whose time signal encodes the geometrical structure of a two-dimensional input image. The signal can be made insensitive to translation, scale, rotation, distortion, and intensity. The waves transmit information beyond the physical interconnect distance. The model is implemented in an optical hybrid demonstration system. Results of the simulations and the optical system are presented.
306 citations
TL;DR: It is suggested that information, resemblance to more familiar foods, and exposure contribute to reducing initially negative responses to novel foods; furthermore, neophobia decreases liking for novel foods similarly at all levels of sensory input (visual, smell and taste).
305 citations
TL;DR: In this article, the authors characterized the dragline silk from the spider, Nephila clavipes, by thermal analysis (TGA, DSC, DMA), computational modeling, scanning electron microscopy and by quasi-static as well as high rates of strain.
Abstract: Dragline silk from the spider, Nephila clavipes, was characterized by thermal analysis (TGA, DSC, DMA), computational modeling, scanning electron microscopy and by quasi-static as well as high rates of strain. Thermal stability to about 230°C was observed by TGA, two transitions by DMA, −75°C, representative of localized motion in the amorphous domain, and a main chain motion associated with partial melt at 210°C. Tensile tests indicated average initial modulus, ultimate tensile strength and ultimate tensile strain of 22 GPa, 1.1 GPa and 9%, respectively. The corresponding properties of the best fibers tested were 60 GPa, 2.9 GPa and 11%, respectively. High strain rates (>50,000%/sec) indicated similar mechanical properties to the average values indicated above. Microscopy showed compressive and tensile strains to failure of 34%. Computational modeling yielded a crystal modulus of 200 GPa.
271 citations
TL;DR: Findings can improve occupational safety guidelines for human heat exposure, as they provide further evidence that the incidence of exhaustion from heat strain can be predicted from core temperature.
Abstract: This study determined the influence of exercise intensity, protective clothing level, and climate on physiological tolerance to uncompensable heat stress. It also compared the relationship between core temperature and the incidence of exhaustion from heat strain for persons wearing protective clothing to previously published data of unclothed persons during uncompensable heat stress. Seven heat-acclimated men attempted 180-min treadmill walks at metabolic rates of approximately 425 and 600 W while wearing full (clo = 1.5) or partial (clo = 1.3) protective clothing in both a desert (43 degrees C dry bulb, 20% relative humidity, wind 2.2 m/s) and tropical (35 degrees C dry bulb, 50% relative humidity, wind 2.2 m/s) climate. During these trials, the evaporative cooling required to maintain thermal balance exceeded the maximal evaporative capacity of the environment and core temperature continued to rise until exhaustion from heat strain occurred. Our findings concerning exhaustion from heat strain are 1) full encapsulation in protective clothing reduces physiological tolerance as core temperature at exhaustion was lower (P < 0.05) in fully than in partially clothed persons, 2) partial encapsulation results in physiological tolerance similar to that reported for unclothed persons, 3) raising metabolic rate from 400 to 600 W does not alter physiological tolerance when subjects are fully clothed, and 4) physiological tolerance is similar when subjects are wearing protective clothing in desert and tropical climates having the same wet bulb globe thermometer. These findings can improve occupational safety guidelines for human heat exposure, as they provide further evidence that the incidence of exhaustion from heat strain can be predicted from core temperature.
253 citations
Patent•
07 Mar 1994TL;DR: In this article, a novel ceramic ferroelectric material having a low dielectric constant, extremely low loss and high tunability was proposed, which is a composite consisting of Barium Strontium Titanate (BSTO) and a ceramic material.
Abstract: A novel ceramic ferroelectric material having a low dielectric constant, extremely low loss and high tunability. The material is a composite comprising Barium Strontium Titanate (BSTO) and a ceramic material having a low dielectric constant. The preferred composite is represented by Ba1-x Srx TiO3 --MgO, wherein x is greater than 0.00, but less than or equal to 0.75, and wherein the percent weight ratio between Ba1-x Srx TiO3 and MgO ranges from approximately 99%-40% and 1%-60%, respectively. The novel materials possess superior electronic properties; and they may be employed in various antenna systems at both microwave and millimeter wave range frequencies.
245 citations
TL;DR: In this paper, a review summarizes information obtained from published literature to determine to what degree biomagnification of organic compounds and metals occurs in freshwater and marine food webs, concluding that the majority of chemicals evaluated (both organic and metals) do not biomagnify in aquatic food webs.
Abstract: This review summarizes information obtained from published literature to determine to what degree biomagnification of organic compounds and metals occurs in freshwater and marine food webs. This review was conducted by: (1) examining data from studies conducted in laboratory experiments to establish body burden ratios between trophic levels (trophic transfer coefficients; TTCs); (2) comparing laboratory-derived TTCs with data obtained from field studies; and (3) comparing biomagnification predictions described by published aquatic food-web models with data obtained in this review. It was determined that: (1) the majority of chemicals evaluated (both organic and metals) do not biomagnify in aquatic food webs; (2) for many of the compounds examined, considerable trophic transfer does occur in aquatic food webs; (3) DDT, DDE, PCBs, toxaphene, methyl mercury, total mercury, and arsenic have the potential to biomagnify in aquatic systems; (4) the lipid fraction of receptors directly influences biomagnification of lipophilic compounds; (5) the food web model reviewed provided similar estimates for most of the organic compounds examined (log Kow values between 5 and 7), with model predictions falling within the range of values of all compounds except dieldrin; (6) for many organic compounds, lack of information precludes assessing the relative importance of biomagnification for these contaminants; and (7) even those compounds for which evidence for biomagnification is strongest show considerable variability and uncertainty regarding the magnitude and existence of food-web biomagnification in aquatic systems.
231 citations
TL;DR: The general theory of quantum angular momentum is used to derive the unique Wigner distribution function for arbitrary angular-momentum states, represented as a pseudoprobability distribution in spherical phase space with spherical coordinates θ and cphi.
Abstract: The general theory of quantum angular momentum is used to derive the unique Wigner distribution function for arbitrary angular-momentum states. We give the explicit distribution for atomic angular-momentum Dicke states, coherent states, and squeezed states that correspond to a collection of N two-level atoms. These Wigner functions W(\ensuremath{\theta},cphi) are represented as a pseudoprobability distribution in spherical phase space with spherical coordinates \ensuremath{\theta} and cphi on the surface of a sphere of radius \ensuremath{\Elzxh} \ensuremath{\surd}j(j+1) where j is the total angular-momentum eigenvalue.
TL;DR: In this article, Mill et al. discuss the effects of environmental pollution on the environment and propose an approach to mitigate the environmental impact of greenhouse gas emissions in the air and water.
Abstract: John D. Mill* Environmental Research Institute of Michigan, Arlington, Virginia 22209 Robert R. O'Neil* and Stephan Price* U.S. Air Force Phillips Laboratory, HanscomAFB, Massachusetts 01731 Gerald J. Romick and O. Manuel Uy Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723 E. M. Gaposchkin** Massachusetts Institute of Technology, Lexington, Massachusetts 02173 Glenn C. Light The Aerospace Corporation, Los Angeles, California 90009-2970 W. Walding Moore Jr.** U.S. Army Space and Strategic Defense Command, Huntsville, Alabama 35807-3801 Thomas L. Murdock General Research Corporation, Danvers, Massachusetts 01923 and A. T. Stair Jr. Visidyne, Burlington, Massachusetts 01803
TL;DR: It is reported here that both ultrahigh hydrostatic pressure (UHP) and electroporation induced sublethal injury to bacterial cells surviving the treatments, and the injured cells of both gram-positive and -negative bacteria became sensitive to the bacteriocins pediocin AcH and nisin.
Abstract: We report here that both ultrahigh hydrostatic pressure (UHP) and electroporation (EP) induced sublethal injury to bacterial cells surviving the treatments. The injured cells of both gram-positive and -negative bacteria became sensitive to the bacteriocins pediocin AcH and nisin. Bacteriocins in combination with either UHP or EP have greater antibacterial effectiveness than UHP or EP alone.
TL;DR: In this paper, the 1.54μm luminescence of optically excited Er3+ in ion-implanted epitaxially grown GaN and AlN films using below band-gap excitation was observed.
Abstract: We report the observation of the 1.54‐μm luminescence of optically excited Er3+ in ion‐implanted epitaxially grown GaN and AlN films using below band‐gap excitation. The Er‐implanted layers were co‐implanted with oxygen. At room temperature, this luminescence for GaN grown on sapphire is nearly as intense as it is at 6 or 77 K and exhibits many resolved transitions between crystal‐field levels of the 4I13/2 first excited multiplet and the 4I15/2 ground multiplet.
TL;DR: Both sensory and hedonic ratings of labeled samples changed in the direction of expectations, as compared to baseline values, supporting an assimilation model of the effect of disconfirmed expectations on sensory perception and consumer acceptance.
TL;DR: A phylogenic tree by pairwise comparison of the deduced amino acid sequences encoded in the medium (M) genome segments of 13 hantaviruses was constructed and a sixth unique hantvirus group represented by Dobrava virus, an Apodemus isolate from Slovenia was identified.
TL;DR: Current research suggests that CDT is of limited value in identifying problematic drinking in general medical or community settings in which a broad continuum of drinkers is represented; combining CDT with other biochemical or self-report screening measures may, however, improve sensitivity in these contexts.
Abstract: A growing body of investigations demonstrate that elevated levels of carbohydrate-deficient transferrin (CDT) effectively distinguishes alcoholics recently consuming large amounts of alcohol from light social drinkers or teetotalers. Nevertheless, important questions still remain concerning the value of CDT as a more generalized marker of alcohol consumption. Most important, the nature of the drinking pattern, including quantity and frequency, necessary to raise levels of CDT significantly remains unclear. Neither has research convincingly demonstrated that CDT is as accurate a marker for women, young adults, or non-Caucasian ethnic groups as for White, middle-aged men. Whereas CDT might serve as a useful outcome measure in trials of alcoholism treatment effectiveness, current research suggests that CDT is of limited value in identifying problematic drinking in general medical or community settings in which a broad continuum of drinkers is represented. Combining CDT with other biochemical or self-report screening measures may, however, improve sensitivity in these contexts. At present, the most accurate laboratory technique to detect CDT seems to be isoelectric focusing. Additional research, however, is needed to resolve the issue of whether CDT is best quantitated as a simple value or if its ratio to total transferrin or non-CDT results in higher predictive validity.
TL;DR: It is proposed that in vivo, malaria pigment from parasites sequestered in the host microvasculature is a physiologically relevant moiety that interacts with monocytes and stimulates the release of TNF-alpha and IL-1 beta.
Abstract: We show that high levels of tumor necrosis factor-alpha (TNF-alpha) activity were consistently detected when monocytes were cocultured with Plasmodium falciparum schizont stage-parasitized erythrocytes that subsequently ruptured. Isolated pigment recovered from ruptured schizonts was found to specifically induce monocyte release of high levels of TNF-alpha and interleukin-1 beta (IL-1 beta). Particulate free-culture supernatant that contained various soluble parasite macromolecules induced relatively low levels of TNF-alpha and IL-1 beta. When isolated pigment was treated with protease, the monokine inducing-activity was abolished. Isolated pigment prepared from different natural isolates of P. falciparum stimulated variable levels of monokine production. We propose that in vivo, malaria pigment from parasites sequestered in the host microvasculature is a physiologically relevant moiety that interacts with monocytes and stimulates the release of TNF-alpha and IL-1 beta. These observations suggest that malaria pigment may be a virulence factor in the monokine-mediated induction of organ-specific and systemic pathophysiology in falciparum malaria.
TL;DR: It is found that several epitopes defined by monoclonal antibodies to the G2 protein were highly conserved as detected by HAI tests and ELISA, and almost all of the isolates could be neutralized by at least one G2-specific monOClonal antibody.
TL;DR: A new image thresholding technique is presented which uses the relative entropy (also known as the Kullback-Leiber discrimination distance function) as a criterion of thresholding an image and provides the least computational complexity.
TL;DR: The development of VEPAB is described and the results of two experiments are summarized, one to test the sensitivity of the tasks to differences between input control devices and the other to examine practice effects.
Abstract: The Virtual Environment Performance Assessment Battery VEPAB is a set of tasks developed to support research on training applications of virtual environment VE technology. VEPAB measures human performance on vision, locomotion, tracking, object manipulation, and reaction time tasks performed in three-dimensional, interactive VEs. It can be used to provide a general orientation for interacting in VEs and to determine both entry level performance and skill acquisition of users. In addition, VEPAB allows comparison of task performance, side effects and aftereffects, and subjective reactions across different VE systems. By providing benchmarks of human performance, VEPAB can promote continuity in training research involving different technologies, separate research facilities, and dissimilar subject populations. This paper describes the development of VEPAB and summarizes the results of two experiments, one to test the sensitivity of the tasks to differences between input control devices and the other to examine practice effects.
Patent•
22 Apr 1994TL;DR: In this article, a movement and sound monitor and stimulator for preventing death in human infants from sudden infant death syndrome is described, where a circuit is connected to monitor the output signal from a transducer and activate a stimulator which is operable to provide movement to the base member to stimulate movement in the object when output from the transducers to the circuit corresponds to no movement from the object.
Abstract: A movement and sound monitor and stimulator which is particularly useful for preventing death in human infants from sudden infant death syndrome is disclosed. The movement and sound monitor and stimulator has a base member which may be a fluid-filled sensing pad for supporting the infant or other animate object which is being monitored and a transducer positioned for detecting movement or acoustic activity (e.g., heartbeat, breathing) of the object on the base member to provide an output signal in response to forces applied thereto which are generated by such movement. A circuit is connected to monitor the output signal from the transducer and activates a stimulator which is operable to provide movement to the base member to stimulate movement in the object when output from the transducer to the circuit corresponds to no movement from the object. The transducer may be a pressure transducer in fluid communication with the fluid interior of the sensing pad. In the alternative, a piezo-electric sheet operatively connected to a surface of the sensing pad to detect such movement as well as movement cessation. The circuit may also be connected to an alarm which can provide an audible or visual indication to third parties when there is no movement from the object.
TL;DR: In this article, a three parameter Weibull distribution is fitted to the observed storm peak data giving due consideration to data censoring, and the use of the peaks over threshold method is recommended.
Abstract: Recommended methods for the statistical analysis of extreme waves are presented. Proper data selection is stressed. Data from different seasons and/or of different type or origin should be analysed separately. Use of the peaks over threshold method is recommended. It is advised that a three parameter Weibull distribution is fitted to the observed storm peak data giving due consideration to data censoring.
TL;DR: The data indicate that the incidence of training-related injuries in infantry units is high and a number of modifiable injury risk factors were identified, suggesting that many of these injuries may be preventable.
TL;DR: In this paper, failure modes of Spectra polyethylene fiber-reinforced composites were examined under ballistic impact loading, and they were found to exhibit sequential delamination, cut-out of a plug induced by through-the-thickness shear, and combined modes of shear and tensile failure offibers in the cases of glass and graphite fiber composites.
Abstract: Failure modes of Spectra polyethylene fiber-reinforced composites were examined under ballistic impact loading. Both woven fabric-reinforced laminates and angle-plied unidirectional fiber-reinforced laminates were found to exhibit sequential delamination, cut-out of a plug induced by through-the-thickness shear, and combined modes of shear and tensile failure offibers as obserxed in the cases of glass and graphite fiber composites. At low areal density, both laminates demonstrated similar ballistic limits. However, as areal density increased, differences in ballistic limit became more apparent, with angle-plied composite laminates showing higher values. When subjected to the repeated impact of a constant striking velocity below the ballistic limit, a progressive growth of local delamination was observed until gross failure of composites occurred. The use of lower striking velocity of the projectile led to the increase in cumulative numbers of impacts for full penetration defining an impact fatigue lifetim...
Patent•
11 Jul 1994TL;DR: In this article, a rotatable and vertically movable susceptor/wafer carrier is used for a chemical vapor deposition reactor with a large diameter disk, which provides the capability of varying the plasma-substrate distance.
Abstract: The present invention provides for a chemical vapor deposition reactor cher which is fitted with a rotatable and vertically movable susceptor/wafer carrier. The susceptor/wafer carrier, which is a large diameter disk, provides the reactor with the capability of varying the plasma-substrate distance. As those skilled in the art will appreciate, such a susceptor allows high deposition rates to be achieved for a given power level because the flux of the reactant can be increased due to the high speed rotation which will decrease boundary layer thickness during growth. The ability to adjust the source-substrate distance gives more flexibility than fixed dimensional systems. Further, it allows damage in the thin films to be minimized by simple adjustments to the susceptor/wafer carrier. Because the damage to the thin films is minimized, it makes pulsed operation practical and therefore, the films may be grown in an atomic layer epitaxy mode to produce films of high quality and uniformity.
Journal Article•
TL;DR: The newly revised and illustrated keys to adult female and fourth instar larval mosquitos presented in this paper will enable public health workers to rapidly identify mosquito vectors of these diseases and to distinguish them from other species in the same genera.
Abstract: The major mosquito-borne diseases in Thailand are malaria, dengue, Japanese encephalitis, and filariasis. The newly revised and illustrated keys to adult female and fourth instar larval mosquitos presented in this paper will enable public health workers to rapidly identify mosquito vectors of these diseases and to distinguish them from other species in the same genera. Keys are provided to identify 4 medically important genera from among any mosquito in Thailand. The 4 genera are treated in more detail with keys to 9 subgenera, 11 groups or subgroups, and 38 individual species considered to be of medical importance.
01 Sep 1994
TL;DR: In this article, a comprehensive experimental investigation of the pressure distribution over a semispan wing undergoing pitching motions representative of a helicopter rotor blade was conducted Testing the wing in the nonrotating condition isolates the three-dimensional (3D) blade aerodynamic and dynamic stall characteristics from the complications of the rotor blade environment.
Abstract: A comprehensive experimental investigation of the pressure distribution over a semispan wing undergoing pitching motions representative of a helicopter rotor blade was conducted Testing the wing in the nonrotating condition isolates the three-dimensional (3-D) blade aerodynamic and dynamic stall characteristics from the complications of the rotor blade environment The test has generated a very complete, detailed, and accurate body of data These data include static and dynamic pressure distributions, surface flow visualizations, two-dimensional (2-D) airfoil data from the same model and installation, and important supporting blockage and wall pressure distributions This body of data is sufficiently comprehensive and accurate that it can be used for the validation of rotor blade aerodynamic models over a broad range of the important parameters including 3-D dynamic stall This data report presents all the cycle-averaged lift, drag, and pitching moment coefficient data versus angle of attack obtained from the instantaneous pressure data for the 3-D wing and the 2-D airfoil Also presented are examples of the following: cycle-to-cycle variations occurring for incipient or lightly stalled conditions; 3-D surface flow visualizations; supporting blockage and wall pressure distributions; and underlying detailed pressure results
TL;DR: Insulin-like growth factor-1 therapy has a beneficial effect in preserving lean body mass during severe stress conditions by minimizing the flux of amino acids toward oxidation.
Abstract: ObjectiveThe effect of insulin-like growth factor-1 (IGF-1) on energy expenditure and protein and glucose metabolism in a group of patients with thermal injury was determined.Summary Background DataAccelerated protein catabolism is a constant feature of the hypermetabolic response to thermal injury.
TL;DR: It is suggested that HI6 could replace 2-PAM as therapy for nerve agent poisoning, because it is superior to 2- PAM against soman, and when used in pyridostigmine-pretreated animals, it affords excellent protection against all four nerve agents when use in combination with atropine (alone or together with diazepam) therapy.