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The one-dimensional isothermal flow of viscous-liquid fibers displays draw resonance instability when a constant-velocity winder condition is applied. This instability is removed when a constant-force condition occurs at the winder. The instability mechanism is examined and used to explain the stability trends when the effects of gravity, surface tension, inertia, and wind stress are included.

An enzyme-linked immunosorbent assay (ELISA) is described for Pseudomonas aeruginosa exotoxin A. A double antibody sandwich method was used, employing polyvinyl microtiter plates as the solid phase, a primary coat of monospecific rabbit antitoxin serum, an outer layer composed of a horseradish peroxidase-sheep antitoxin immunoglobulin G conjugate, and an ortho-phenylene-diamine substrate. Absorbance (optical density) of hydrolyzed end product was read spectrophotometrically at 492 nm. ELISA detected as little as 30 pg (0.3 ng/ml) of purified toxin, and absorbance was linear over a 20-fold or greater concentration range. Toxin was demonstrated in culture filtrates from 42 of 48 (88%) consecutive clinical P. aeruginosa isolates compared with 37 of 48 (77%) positive by hemagglutination inhibition. Results of the two assays correlated closely (r = 0.82, P less than 0.001). Specificity was confirmed by neutralizability of ELISA activity with monospecific antitoxin. ELISA was thus a sensitive, specific, and quantifiable technique for the assay of P. aeruginosa exotoxin A in both purified and crude culture materials.

Fluid flow under a grinding wheel is modeled using a perturbation scheme. In this initial effort to understand the flow characteristics, we concentrate on the case of a smooth wheel with slight clearance between the wheel and workpiece. The solution at lowest order is that given by standard lubrication theory. Higher-order terms correct for inertial and two-dimensional effects. Experimental and analytical pressure profiles are compared to test the validity of the model. Lubrication theory provides good agreement with low Reynolds number flows; the perturbation scheme provides reasonable agreement with moderate Reynolds number flows but fails at high Reynolds numbers. Results from experiments demonstrate that the ignored upstream and downstream conditions significantly affect the flow characteristics, implying that only a model based on the fully two- (or three-) dimensional Navier-Stokes equations will accurately predict the flow. We make one comparison between an experiment with a grinding wheel and the model incorporating a one-dimensional sinusoidal roughness term. For this case, lubrication theory surprisingly provides good agreement with experiment.

Lynchburg fecal virus (LFV), originally isolated from the stool of an infectious hepatitis patient, was passaged 15 times in WI-38 cells and partially characterized. Its properties are as follows: RNA virus; 27 nm in diameter, picornavirus-like morphology; inactivated at 56 C for 60 minutes; resistant to treatment with hydrochloric acid (pH 3.0), chloroform (33%), and diethyl ether (20%). Neutralization studies indicated that LFV is antigenically related to coxsackievirus A-24 but not to prototype hepatitis A virus (HAV). The simultaneous occurrence of infections with LFV and with HAV was indicated by the results of enzyme immunoassay (EIA) of the sera of patients of the Lynchburg outbreak. Absence of anti-LFV in patient sera was accompanied by an absence of anti-HAV and, conversely, an increased titer in anti-LFV was accompanied by an increased titer in anti-HAV. Each antibody type was shown to be elicited independently indicating simultaneous infections with LFV and HAV. The contribution, if any, of LFV to disease in the outbreak remains unknown.

The growth of some obligate intracellular parasites is contingent upon avoidance of lysosomal activation during growth in their host cells. This is accomplished by the various parasites by different mechanisms and with different degrees of efficiency. The possibility was tested that the lysosomal stabilizer cortisone acetate might protect and thus enhance the growth of Rickettsia typhi in mouse L cells irradiated 6 days earlier. Beginning 2 days before infection of the L cells with a multiplicity of 10 rickettsiae, 20 microgram of cortisone per ml was added in medium 199 containing 5% fetal calf serum. This concentration of cortisone was below the cytotoxic level, as determined by viability staining, but was sufficient to significantly alter the ratios of cellular and released acid phosphatase and beta-glucuronidase in uninfected and infected cells, as shown by spectrophotometric analysis. Rickettsial replication, measured by hemolytic activity at 96 h and confirmed by microscopic observations at earlier stages of infection, was increased by the cortisone. Cortisone concentrations of 10 or 40 microgram/ml were less effective, and cortisone was ineffective when the rickettsial multiplicity per L cell was 2 or lower. These results indicate that amounts of cortisone that increase lysosomal stabilization in L cells favor rickettsial multiplication when the multiplicity of infection is relatively high.

Lyosomal myeloperoxidase activity in human phagocytic leucocytes was stimulated by incubation with virulent (T1) and avirulent (T4) forms of Neisseria gonorrhoeae. The amount of activity, assayed by bacterial iodination (125-iodine) after 30 min. exposure to the pagocytes in the absence of serum, was about fifty times greater in cells infected with T4 strains. In the presence of heated human serum, or its IgG component, myeloperoxidase activity increased, but T1-Stimulated activity was significantly less than that of T4 and was not proportional to multiplicity of infection. From these results and from those of a previous study we conclude that T1 can stimulate leucocyte myeloperoxidase activity from an extracellular location, that for this activity a serum fraction is required, and that this may be a mechanism responsible for some of the killing of the membrane associated T1. [ABSTRACT FROM PUBLISHER]

Equipment and techniques previously used to investigate the effect of hyperbaric gases on bacteria were modified to permit comparable investigations with uninfected and virus-infected tissue cell cultures. This report describes the modified equipment and related methodology. Use of the system is illustrated with findings on the effect of oxygen-helium mixtures at 68 atm on cell physiology and virus growth in two cell types. Our results suggested that, under those experimental conditions, several synthetic processes in chick fibroblast monolayers are inhibited but that Sindbis virus growth in the cells is increased. Growth of Japanese encephalitis virus in porcine kidney cells was found to be unaffected by oxygen-helium gas at partial pressures of oxygen between 0 and 700 mm Hg, but morphological alterations in the cells occurred at low and high pO2levels.

The article presents the study on an assymetric laser communication (lasercom) developed by the U.S. Naval Research Laboratory for small unmanned aerial systems (UASs). It states that the lasercom was developed due to the increasing reliance on UASs and the development of sensors that require higher-bandwidths. It also describes the components of the airborne lasercom transceiver and the Dakota Wingpod Lasercom System.