1862-11-01 A.W. Norcross forwards a letter from Charles Hendrickson requesting discharge

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Positional Awareness Map 3D (PAM3D)

The Western Aeronautical Test Range of the National Aeronautics and Space Administration s Dryden Flight Research Center needed to address the aging software and hardware of its current situational awareness display application, the Global Real-Time Interactive Map (GRIM). GRIM was initially developed in the late 1980s and executes on older PC architectures using a Linux operating system that is no longer supported. Additionally, the software is difficult to maintain due to its complexity and loss of developer knowledge. It was decided that a replacement application must be developed or acquired in the near future. The replacement must provide the functionality of the original system, the ability to monitor test flight vehicles in real-time, and add improvements such as high resolution imagery and true 3-dimensional capability. This paper will discuss the process of determining the best approach to replace GRIM, and the functionality and capabilities of the first release of the Positional Awareness Map 3D

Nonlinear dynamics of a solid-state laser with injection

We analyze the dynamics of a solid-state laser driven by an injected sinusoidal field. For this type of laser, the cavity round-trip time is much shorter than its fluorescence time, yielding a dimensionless ratio of time scales $\sigma \ll 1$. Analytical criteria are derived for the existence, stability, and bifurcations of phase-locked states. We find three distinct unlocking mechanisms. First, if the dimensionless detuning $\Delta$ and injection strength $k$ are small in the sense that $k = O(\Delta) \ll \sigma^{1/2}$, unlocking occurs by a saddle-node infinite-period bifurcation. This is the classic unlocking mechanism governed by the Adler equation: after unlocking occurs, the phases of the drive and the laser drift apart monotonically. The second mechanism occurs if the detuning and the drive strength are large: $k =O(\Delta) \gg \sigma^{1/2}$. In this regime, unlocking is caused instead by a supercritical Hopf bifurcation, leading first to phase trapping and only then to phase drift as the drive is decreased. The third and most interesting mechanism occurs in the distinguished intermediate regime $k, \Delta = O(\sigma^{1/2})$. Here the system exhibits complicated, but nonchaotic, behavior. Furthermore, as the drive decreases below the unlocking threshold, numerical simulations predict a novel self-similar sequence of bifurcations whose details are not yet understood.Comment: 29 pages in revtex + 8 figs in eps. To appear in Phys. Rev. E (scheduled tentatively for the issue of 1 Oct 98

"Boom" and "Bust" cycles in virus growth suggest multiple selective forces in influenza a evolution

<p>Abstract</p> <p>Background</p> <p>Influenza A virus evolution in humans is driven at least in part by mutations allowing the virus to escape antibody neutralization. Little is known about the evolution of influenza in birds, a major reservoir of influenza A.</p> <p>Methods</p> <p>Neutralizing polyclonal antiserum was raised in chicken against reassortant influenza virus, CalX, bearing the hemagglutinin (HA) and neuraminidase (NA) of A/California/7/2004 [H3N2]. CalX was serially passaged in the presence of anti-CalX polyclonal IgY to derive viruses capable of growth in the presence of antibody.</p> <p>Results</p> <p>Polyclonal chicken antibody neutralized both HA activity and infection by CalX, but had no effect on a strain bearing an earlier human H3 and an irrelevant neuraminidase (A/Memphis/71-Bellamy/42 [H3N1]). Surprisingly, most of the antibody-resistant viruses were still at least partially sensitive to neutralization of HA activity and viral infection. Although mutant HA genes bearing changes that might affect antibody neutralization were identified, the vast majority of HA sequences obtained were identical to wild type, and no individual mutant sequence was found in more than one passage, suggesting that those mutations that were observed did not confer sufficient selective advantage to come to dominate the population. Different passages yielded infectious foci of varying size and plaques of varying size and morphology. Yields of infectious virus and relative frequency of different morphologies changed markedly from passage to passage. Sequences of bulk, uncloned PCR products from antibody-resistant passages indicated changes in the PB2 and PA proteins with respect to the wild type virus.</p> <p>Conclusions</p> <p>Each antibody-selected passage consisted of a variety of different cocirculating populations, rather than pure populations of virus able to escape antibody by changes in antibody epitopes. The ability to escape antibody is apparently due to changes in genes encoding the viral polymerase complex, probably resulting in more robust viral replication, allowing the few virus particles not completely neutralized by antibody to rapidly produce large numbers of progeny. Our data suggest that the relative success of an individual variant may depend on both its own gain and loss of fitness, as well as that of its cocirculating variants.</p

Retarded long-range potentials for the alkali-metal atoms and a perfectly conducting wall

The retarded long-range potentials for hydrogen and alkali-metal atoms in their ground states and a perfectly conducting wall are calculated. The potentials are given over a wide range of atom-wall distances and the validity of the approximations used is established.Comment: RevTeX, epsf, 11 pages, 2 fig

A comparison of pneumolysin activity and concentration in vitro and in vivo in a rabbit endophthalmitis model

The purpose of this study was to determine whether the in vitro activity and concentration of Streptococcus pneumoniae pneumolysin correlated to the pathogenesis of S. pneumoniae endophthalmitis. Five S. pneumoniae clinical endophthalmitis strains were grown in media to similar optical densities (OD), and extracellular milieu was tested for pneumolysin activity by hemolysis of rabbit red blood cells. Pneumolysin concentration was determined using a sandwich ELISA. Rabbit vitreous was injected with 102 colony-forming units (CFU) of 1 of 2 different strains with low hemolytic activity (n = 10 and 12 for strains 4 and 5, respectively) or 1 of 3 different strains with high hemolytic activity (n = 12 per strain). Pathogenesis of endophthalmitis infection was graded by slit lamp examination (SLE) at 24 hours post-infection. Bacteria were recovered from infected vitreous and quantitated. The SLE scores of eyes infected with strains having high hemolytic activity were significantly higher than the scores of those infected with strains having low hemolytic activity (P < 0.05). Pneumolysin concentration in vitro, however, did not correlate with hemolysis or severity of endophthalmitis. Bacterial concentrations from the vitreous infected with 4 of the strains were not significantly different (P > 0.05). These data suggest that pneumolysin hemolytic activity in vitro directly correlates to the pathogenesis of S. pneumoniae endophthalmitis. The protein concentration of pneumolysin, however, is not a reliable indicator of pneumolysin activity

Absence of \u3ci\u3eStreptococcus pneumoniae \u3c/i\u3e Capsule Increases Bacterial Binding, Perisstence, and Inflammation In Corneal Infection

The role of the pneumococcal polysaccharide capsule is largely unclear for Streptococcus pneumoniae keratitis, an ocular inflammatory disease that develops as a result of bacterial infection of the cornea. In this study, capsule-deficient strains were compared to isogenic parent strains in their ability to adhere to human corneal epithelial cells. One isogenic pair was further used in topical ocular infection of mice to assess the contribution of the capsule to keratitis. The results showed that non-encapsulated pneumococci were significantly more adherent to cells, persisted in significantly higher numbers on mouse corneas in vivo, and caused significant increases in murine ocular IL9, IL10, IL12-p70, MIG, and MIP-1-gamma compared to encapsulated S. pneumoniae. These findings indicate that the bacterial capsule impedes virulence and the absence of capsule impacts inflammation following corneal infection

Ground Reaction Forces and Gait Parameters during Motorized and Non-Motorized Treadmill Walking and Runing on the International Space Station Treadmill

Both motorized (T-M) and non-motorized (T-NM) treadmill locomotion are used on the International Space Station (ISS) as countermeasures to the deleterious effects of prolonged weightlessness. However, the ground reaction forces (GRF) and gait parameters of these exercise modes have not been examined. The purpose of this study was to determine if differences in GRF and gait parameters exist while walking (1.34 m/s) and running (3.13 m/s) on T-M and T-NM. Dissimilar GRF and gait parameters suggest that T-M and T-NM locomotion may elicit different physiologic effects. T-NM may result in a reduced stimulus to bone formation due to a lower LR, but an increased energy cost as a result of shorter, more frequent strides. Therefore, the usage of each mode should depend upon the desired training stimulus

Time-dependent calculation of ionization in Potassium at mid-infrared wavelengths

We study the dynamics of the Potassium atom in the mid-infrared, high intensity, short laser pulse regime. We ascertain numerical convergence by comparing the results obtained by the direct expansion of the time-dependent Schroedinger equation onto B-Splines, to those obtained by the eigenbasis expansion method. We present ionization curves in the 12-, 13-, and 14-photon ionization range for Potassium. The ionization curve of a scaled system, namely Hydrogen starting from the 2s, is compared to the 12-photon results. In the 13-photon regime, a dynamic resonance is found and analyzed in some detail. The results for all wavelengths and intensities, including Hydrogen, display a clear plateau in the peak-heights of the low energy part of the Above Threshold Ionization (ATI) spectrum, which scales with the ponderomotive energy Up, and extends to 2.8 +- 0.5 Up.Comment: 15 two-column pages with 15 figures, 3 tables. Accepted for publication in Phys. Rev A. Improved figures, language and punctuation, and made minor corrections. We also added a comparison to the ADK theor