Showing papers by "United States Department of the Army published in 1984"

Statistical Theory of Passive Location Systems

Abstract: A derivation of the principal algorithms and an analysis of the performance of the two most important passive location systems for stationary transmitters, hyperbolic location systems and directionfinding location systems, are presented. The concentration ellipse, the circular error probability, and the geometric dilution of precision are defined and related to the location-system and received-signal characteristics. Doppler and other passive location systems are briefly discussed.

Microgravimetric and gravity gradient techniques for detection of subsurface cavities

Abstract: . Microgravimetric and gravity gradient surveying techniques are applicable to the detection and delineation of shallow subsurface cavities and tunnels. Two case histories of the use of these techniques to site investigations in karst regions are presented. In the first case history, the delineation of a shallow (_ 10 m deep), airfilled cavity system by a microgravimetric survey is demonstrated. Also, application of familiar ring and center point techniques produces derivative maps which demonstrate (1) the use of second derivative techniques to produce a “residual” gravity map, and (2) the ability of first derivative techniques to resolve closely spaced or complex subsurface features. In the second case history, a deeper (-30 m deep), water-filled cavity system is adequately detected by a microgravity survey. Results of an interval (tower) vertical gradient survey along a profile line are presented in the second case history; this vertical gradient survey successfully detected shallow (< 6 m) anomalous features such as limestone pinnacles and clay pockets, but the data are too “noisy” to permit detection of the vertical gradient anomaly caused by the cavity system. Interval horizontal gradients were determined along the same profile line at the second site, and a vertical gradient profile is determined from the horizontal gradient profile by a Hilbert transform technique. The measured horizontal gradient profile and the computed vertical gradient profile compare quite well with corresponding profiles calculated for a two-dimensional model of the cavity system.

The Effect of Dental Amalgam Restorations on Blood Mercury Levels

Abstract: Mercury levels in blood and in mouth air before and after chewing were measured in 47 persons with ana 14 persons without dental amalgam restorations. Questionnaires relating to exogenous sources of mercury exposure were administered to both groups. Differences in the mouth air mercury levels before and after chewing were statistically significant in the group with amalgams, but not in the group without amalgams. Analysis of the data from the questionnaires indicated that little or no exogenous exposure to mercury occurred among the two groups. Blood mercury concentrations were positively correlated with the number and surface area of amalgam restorations and were significantly lower in the group without dental amalgams.

Effect of environmental factors on aerosol-induced Lassa virus infection.

Abstract: Previous studies suggested that the most frequent means of transmission of Lassa virus was by either direct or indirect contact with infectious material. Aerosol stability and respiratory infectivity of the Josiah strain of Lassa virus were assessed to determine the effect of environmental factors on aerosol-induced infection. The stability of the virus in aerosol, particularly at low relative humidity (30% RH), plus the ability of the virus to infect guinea pigs and monkeys via the respiratory route emphasize the potential for aerosol transmission of Lassa virus. Biological half-lives at both 24 and 32 degrees C ranged from 10.1 to 54.6 min, and were sufficient for aerosol dispersion of virus to considerable distances in natural situations. Infectivity of Lassa virus in small particle aerosol was demonstrated in outbred guinea pigs and cynomolgus monkeys using dynamic aerosol equipment. Monkeys exposed to inhaled doses to 465 PFU were infected and died. The median infectious dose (ID50) for guinea pigs was 15 PFU, yet a definitive median lethal aerosol dose (LD50) could not be established. Organ tropism of aerosol-induced Lassa virus infections in outbred guinea pigs was similar to that previously reported for inbred guinea pigs infected by subcutaneous inoculation.

Competitive adsorption of cellulase components and its significance in a synergistic mechanism

Abstract: Some studies on the adsorption of cellulase on cellulose revealed part of the mechanisms involved in the enzymatic hydrolysis of cellulose and provided some clues to the synergistic mechanism of cellulase complex. The adsorption of cellulase was significantly affected by the reaction conditions and physical chemical characteristics of cellulose. Endoglucanase consisted of adsorbable and nonadsorbable components. Cellobiohydrolase had the strongest adsorption affinity. Each cellulase component is postulated to have distinctly different adsorption sites on cellulose, corresponding to the active sites in the hydrolysis reaction. Competitive adsorption kinetics between cellulase components were also observed during the adsorption process. The degree of competitive adsorption was most remarkable when the composition of cellulase components was nearly the same as that in the crude cellulase complex. This seems to show the optimal relative composition of cellulase components. The synergism between cellobiohydrolase and endoglucananse could be elucidated more clearly by this competitive adsorption model of the reaction mechanism.

Dual lens antenna with mechanical and electrical beam scanning

Abstract: A mechanically positioned phase steered transfer lens which is illuminatedy a fixed collimation lens. Wide angle scan is accomplished by tilting the movable lens and electronically scanning the beam to the desired angle. The mechanical motion minimizes the required electronic scan angles, thus minimizing the number of phase shifters required.

The effect of organosolv pretreatment on the enzymatic hydrolysis of poplar

Abstract: The use of alcohol/water/catalyst mixtures to delignify wood allows the lignin to be recovered in a usable form while leaving the carbohydrate fraction relatively intact. The effects of temperature, reaction time, and the type of solvent and catalyst on the delignification of milled poplar wood were investigated. The lignin, cellulose, and hemicellulose composition of the pretreated material was measured for each treatment condition. In addition, the pretreated samples were subjected to enzymatic hydrolysis using the cellulases produced by the thermophilic bacterium Thermomonospora sp. YX. The extent of enzymatic hydrolysis was characterized using an empirical model, and the results were used to examine the effectiveness of the pretreatment.

Polyactic-polyglycolic acid copolymer combined with decalcified freeze-dried bone for use as a bone repair material

Abstract: A novel bone repair material consisting essential of decalcified freeze-dd bone and biodegradable, biocompatible copolymer has been developed for improving and accelerating the healing of osseous tissue. The bone repair material was prepared by combining decalcified bone with a copolymer consisting essentially of a 50:50 poly(L)(-)lactide co-glycolide.

Measurement and Prediction of Thermal Injury in the Retina of the Rhesus Monkey

Abstract: The authors measured temperature rises with specially designed microthermocouples in over 60 retinae for various image sizes, wavelengths, and exposure durations. Measured temperatures varied with a standard error of 6 percent, and agreed well with a mathematical model for temperature-time response. Observed injury also compared favorably to that predicted by a rate process model for thermal injury. Suggested rate constants for the eye are A = 1.3 ×1099 1/s, and E = 150 000 cal/M. With these coefficients, predicted threshold injury agreed within a factor of two with experimentally determined injury from 10?8 to 103 s. No difference in threshold temperatures was evident between either macular and paramacular exposures or between wavelengths of 488-647 nm. The model can be used to predict injury in the human eye by substituting absorption coefficients and thickness for the human PE and Ch in the thermal portion of the model.

Mirrorless optical bistability with the use of the local-field correction

Abstract: A semiclassical model of two-level atoms driven by a local field is developed. It is shown that this leads to optical bistability without the presence of an optical cavity. The quantitative and qualitative character of this mirrorless bistability is different from cases considered earlier.

Chemical sensor matrix

Abstract: A chemical sensor matrix is provided for sensing the presence of chemical agents by chemo-electronic means. The chemical sensor matrix is comprised of a plurality of resonators embedded in a single monolithic piece of piezoelectric crystal. The resonators are arranged in rectangular row and column configuration including m rows and n columns, each of the resonators being separated from its neighboring resonators by distances such that the resonant energies do not overlap. Each of the resonators is coated with a different chemical substance to be sensitive to a chemical agent to be detected so that when the chemical substance reacts with the chemical agent, the frequency fmn changes. Each of the rows of resonators bears a metallic electrode stripe for that row, and each of said columns of resonators bears a metallic stripe for that column. The electrode row stripes are positioned on the top surface of the crystal, and the electrode column stripes are positioned on the bottom surface of the crystal. The areas of overlap of said row and column stripes are registered with the central portions of the embedded resonators. Two diode arrays are positioned on the periphery of the crystal for addressing the individual row electrode stripes and the individual column electrode stripes so that the desired resonator can be activated by connecting the stripe corresponding to its row address and the stripe corresponding to its column address to suitable active oscillator circuitry and signal processing means. The resonators fmn can then be interrogated sequentially and frequency change registered.

Enhanced Treatment of Lassa Fever by Immune Plasma Combined with Ribavirin in Cynomolgus Monkeys

Abstract: Lassa virus-infected cynomolgus monkeys were treated with Lassa virus-immune monkey serum containing a high concentration of neutralizing antibody, the antiviral drug ribavirin, or a combination of ribavirin plus immune serum at various times after infection. When treatment was initiated early (day 0 or 4), either ribavirin (30 mg/kg of body weight per day) or immune serum alone protected monkeys. However, when the initial treatment was delayed until day 7, only four of eight ribavirin-treated and only one of six serum-treated monkeys survived. Treatment with ribavirin combined with immune serum was more successful; all infected monkeys given combination treatment survived, including six treated initially on day 10. Increased doses of ribavirin given alone were toxic. The empirical observation that combined treatment with ribavirin plus serum results in enhanced survival in experimentally infected monkeys suggests that combined treatment might benefit human patients with Lassa fever as well.

Antitoxin Levels in Botulism Patients Treated with Trivalent Equine Botulism Antitoxin to Toxin Types A, B, and E

Abstract: Serum levels of equine-botulism antitoxin to toxin types A, B, and E were measured in four type-A botulism patients who had received equine-botulism antitoxin. High circulating levels capable of neutralizing in excess of 1 X 10(8), 9 X 10(7), and 6 X 10(6) 50% mouse lethal doses of toxin of types A, B, and E, respectively, were detected. There was little depletion of type-A antitoxin even though two of the patients had circulating type-A toxin before treatment. The half-life for antitoxin persistence for one patient was calculated as being 6.5, 7.6, and 5.3 days for antitoxin types A, B, and E, respectively. Antitoxin levels were not proportionate to the amount (range, 2-4 vials) injected and did not appear to be affected by whether the route of administration was iv or im. Peak serum levels of antitoxin were 10-1,000 times higher than amounts needed to neutralize the toxin measured in the serum of these and other patients with botulism.

Rickettsial Diseases of the Far East: New Perspectives

Abstract: The rickettsial disease of man found only in Asia is mite-borne (scrub) typhus, caused by Rickettsia tsutsugamushi. Unique to southern Japan is a little-known human mononucleosis-like disease caused by Rickettsia sennetsu. In 1981 and 1982, there was a remarkable resurgence in the number of reported cases of mite-borne typhus in Japan after some years of virtual absence. Recent studies of R sennetsu have resulted in its reclassification to the genus Ehrlichia, members of which until now have been exclusively pathogens of animals. The historical background of ecologic investigations, in Malaysia and elsewhere, of these two developments suggest directions for future research.

Cutaneous leishmaniasis in Kenya: transmission of Leishmania major to man by the bite of a naturally infected Phlebotomus duboscqi

Abstract: One leishmanial stock was isolated from a Phlebotomus duboscqi female captured in Baringo District, Kenya, and others from papular lesions that developed at sites where this sandfly had fed on a man. When characterized by cellulose acetate electrophoresis (eight enzymes examined), these isolates proved to be identical to known Leishmania major strains from man and a rodent (Arvicanthis sp.) and different from L. donovani and L. adleri, which also occur in Baringo. This is the first case of human cutaneous leishmaniasis caused by L. major reported from Kenya.

Pathology Produced by Sulfur Mustard in Human Skin Grafts on Athymic Nude Mice. I. Gross and Light Microscopic Changes

Abstract: Sulfur mustard (SM) is a powerful vesicant in humans whose pathogenic mechanism is not well understood and an agent for which no effective therapy exists. We selected human skin grafted to congenitally athymic nude mice to study SM-induced injury because the injury in various animal models differs from skin injury in humans. Grafts made from full-thickness human neonatal foreskin or from partial-thickness adult facial, mammary, and abdominal skin were exposed to SM in either the liquid or vaporized form. The course of injury was followed at the gross, light microscopic, and ultrastructural levels. Morphologic changes were correlated to the dose. Changes occurring at the ultrastructural level are reported in a companion paper. Skin lesions in grafts had many features in common with those reported previously in humans including (a) similar dose-response for both liquid and vapor exposures; (b) similar time course for the appearance of overt pathology, preceded by a typical asymptomatic latent period...

The HCH‐1 model of enzymatic cellulose hydrolysis

Abstract: Solka Floc BW200 was enzymatically hydrolyzed in a batch reactor using a commercial cellulase preparation. A total of 50 different hydrolysis conditions were run within a 10-fold range in enzyme concentration and a 30-fold range in cellulose concentration. The data were evaluated in three ways using five different models. Previous literature models were not as successful in correlating the data as the HCH-1 Model derived in this work.

Time Scales of Nearshore Profile Changes

Abstract: Time scales of nearshore profile change are examined using a unique set of highly accurate surveys collected over a 3% year period at CERC's Field Research Facility. The data are analyzed in terms of the formation and movement of the nearshore bars and with empirical eigenfunctions. The largest and most rapid changes in the profiles occurred during storms. The inner bar (depth of -0.6 to 1.5 m, 1.6 to 4.5 ft) moved offshore during even minor storms and recovered relatively quickly. The outer bar (depth of 3 to 4 m, 9 to 13 ft) formed during the largest storms and recovery was considerably slower, requiring six months or longer. The eigenvector analysis confirmed the importance of storms but identified a seasonal shift of material from the beach and inner bar to the offshore.

Pathology Produced by Sulfur Mustard in Human Skin Grafts on Athymic Nude Mice. II. Ultrastructural Changes

Abstract: The human skin graft/nude mouse model was used to study sulfur mustard (SM) -induced pathology of skin at the ultrastructural level. The electron microscope confirms and extends the histopathology previously noted under light microscopy. SM caused extensive injury to the basal keratinocytes, the severity of which was dependent on both time and dose. Ultrastructurally visible damage took several hours to develop. The following sequence of morphological changes was observed: (a) Extensive condensation and margination of heterochromatin and loss of euchromatin, (b) blebbing of the nuclear membrane, (c) appearance of perinuclear vacuoles, (d) swelling of the endoplasmic reticulum, (e) progressive dissociation of rosettes of free polyribosomes, (f) formation of cytoplasmic vacuoles, (g) loss of the integrity of the basal cell plasma membrane, (h) leakage of cell contents and debris into the lamina lucida, (i) disruption of the anchoring filaments of hemidesmosomes with separation of the plasma membrane...

Mosfet and MOS Capacitor Responses to Ionizing Radiation

Abstract: The ionizing radiation responses of metal oxide semiconductor (MOS) field-effect transistors (FETs) and MOS capacitors are compared. It is shown that the radiation-induced threshold voltage shift correlates closely with the shift in the MOS capacitor inversion voltage. The radiation-induced interface-state density of the MOSFETs and MOS capacitors was determined by several techniques. It is shown that the presence of "slow" states can interfere with the interface-state measurements.

Monolithic planar doped barrier subharmonic mixer

Abstract: A single planar doped barrier diode is grown by the selective deposition of gallium arsenide using molecular beam epitaxy (MBE) in the center of a gallium arsenide dielectric waveguide member mounted on a ground plane. The waveguide member includes two portions which extend in opposite directions and terminating in respective metal to dielectric waveguide transition sections which are coupled to an RF input signal and local oscillator signal, respectively. The planar doped barrier diode operates as an intrinsic subharmonic mixer and accordingly the local oscillator signal has frequency of one half the input signal frequency. An IF output signal is coupled from the mixer diode to a microstrip transmission line formed on an insulating layer fabricated on the ground plane. Dielectric waveguide isolators are additionally included on the dielectric waveguide segments to mutually isolate the input signal and local oscillator signal. A monolithic form of circuit fabrication is thus provided which allows the planar doped barrier mixer circuit to be extremely small and the cost of mass producing such a circuit to be very economical.

Analysis of Damage in MOS Devices for Several Radiation Environments

Abstract: Recent results on hardened and unhardened CMOS inverters are analyzed. New experimental results indicate that lateral hole transport promotes a large interface state buildup in n-channel devices irradiated with the gate grounded. Other prompt results can be explained by recombination models. Annealing results in hardened oxides can be predicted using linear systems theory.