Higher derivative network sensitivities using adjoint network

Higher derivative sensitivity coefficients for a lumped linear time-invariant networks are derived by an extension of the method used by Richards to calculate second derivative sensitivity coefficients. A computer algorithm to generate these coefficients efficiently is provided together with array space and the number of operations required at each stage. Extensions of the above approach for networks containing distributed and nonlinear elements are also discussed. Finally, time domain sensitivity results are derived and the corresponding changes in the computer algorithm indicated.     

Recombinant modified vaccinia virus Ankara-simian immunodeficiency virus gag pol elicits cytotoxic T lymphocytes in rhesus monkeys detected by a major histocompatibility complex class I/peptide tetramer

The utility of modified vaccinia virus Ankara (MVA) as a vector for eliciting AIDS virus-specific cytotoxic T lymphocytes (CTL) was explored in the simian immunodeficiency virus (SIV)/rhesus monkey model. After two intramuscular immunizations with recombinant MVA-SIVSM gag pol, the monkeys developed a Gag epitope-specific CTL response readily detected in peripheral blood lymphocytes by using a functional killing assay. Moreover, those immunizations also elicited a population of CD8+ T lymphocytes in the peripheral blood that bound a specific major histocompatibility complex class I/peptide tetramer. These Gag epitope-specific CD8+ T lymphocytes also were demonstrated by using both functional and tetramer-binding assays in lymph nodes of the immunized monkeys. These observations suggest that MVA may prove a useful vector for an HIV-1 vaccine. They also suggest that tetramer staining may be a useful technology for monitoring CTL generation in vaccine trials in nonhuman primates and in humans.     

Experimental component analysis of a behavioral HIV–AIDS prevention intervention for inner-city women.

A component analysis of a behavioral HIV risk reduction intervention was conducted among 87 women recruited from an inner-city community. Women were randomly assigned to an intervention consisting of (a) sexual communication skills training, (b) self-management skills training, (c) a combination of sexual communication and self-management skills, or (d) HIV education and risk sensitization. Results showed that all 4 intervention conditions increased AIDS knowledge and intentions to reduce risk behaviors. Communication skills training resulted in higher rates of risk reduction conversations and risk refusals. However, the combined skills training condition showed the lowest rates of unprotected sexual intercourse at the 3-month follow-up. This study is the first to experimentally control HIV risk reduction elements in an analysis of a skills-based HIV prevention intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On linear parasitic array of dipoles with reactive loading

Center loaded linear parasitic arrays of dipoles are examined. It is shown that capacitive loading increases the phase velocity of the slow wave on the structure while inductive loading reduces it. For the infinite array, used as a transmission line, this has the effect of modifying the cutoff frequency and the bandwidth. This is experimentally verified for the capacitive loading. For a simple finite array without a reflector, due to end effects only a small bandwidth widening is observed. However, when the finite array is attached with a suitable reflector, a significant widening of bandwidth is observed. In both these cases the loading causes a significant shifting of the center operating frequency. This effect is utilized to build a tunable Yagi array with varactor loading. With variable bias this loading can effectively be adjusted to double the operational bandwidth. Also it is shown that it is possible to sustain the optimum array directivity over a very wide bandwidth without bias adjustments, by a special loading network.     

Combating coevolutionary disengagement by reducing parasite virulence

While standard evolutionary algorithms employ a static, absolute fitness metric, coevolutionary algorithms assess individuals by their performance relative to populations of opponents that are themselves evolving. Although this arrangement offers the possibility of avoiding long-standing difficulties such as premature convergence, it suffers from its own unique problems, cycling, over-focusing and disengagement. Here, we introduce a novel technique for dealing with the third and least explored of these problems. Inspired by studies of natural host-parasite systems, we show that disengagement can be avoided by selecting for individuals that exhibit reduced levels of "virulence", rather than maximum ability to defeat coevolutionary adversaries. Experiments in both simple and complex domains are used to explain how this counterintuitive approach may be used to improve the success of coevolutionary algorithms.     

Vanishing points and three-dimensional lines from omni-directional video

This paper describes a system for structure from motion using vanishing points and three-dimensional lines extracted from omni-directional video sequences. To track lines, we use a novel dynamic programming approach to improve ambiguity resolution, and we use delayed states to aid in the initialization of landmarks. By reobserving vanishing points we get direct measurements of the robots three-dimensional attitude that are independent of its position. Using vanishing points simplifies the representation since parallel lines share the same direction states. We show the performance of the system in various indoor and outdoor environments and include comparisons with independent two-dimensional reference maps for each experiment .     

Laser-driven formation of a high-pressure phase in amorphous silica

Because of its simple composition, vast availability in pure form and ease of processing, vitreous silica is often used as a model to study the physics of amorphous solids. Research in amorphous silica is also motivated by its ubiquity in modern technology, a prominent example being as bulk material in transmissive and diffractive optics for high-power laser applications such as inertial confinement fusion (ICF). In these applications, stability under high-fluence laser irradiation is a key requirement, with optical breakdown occurring when the fluence of the beam is higher than the laser-induced damage threshold (LIDT) of the material. The optical strength of polished fused silica transmissive optics is limited by their surface LIDT. Surface optical breakdown is accompanied by densification, formation of point defects, cratering, material ejection, melting and cracking. Through a combination of electron diffraction and infrared reflectance measurements we show here that synthetic vitreous silica transforms partially into a defective form of the high-pressure stishovite phase under high-intensity (GW cm(-2)) laser irradiation. This phase transformation offers one suitable mechanism by which laser-induced damage grows catastrophically once initiated, thereby dramatically shortening the service lifetime of optics used for high-power photonics.     

Bromide ion mediated modification to digestive ripening process: Preparation of ultra-small Pd,Pt, Rh and Ru nanoparticles

Nanoparticles of catalytically important transition metals, such as Pd, Pt, Rh, and Ru have been prepared by the well-known “digestive ripening” (DR) and “modified digestive ripening” (mDR) methods. In the traditional DR process, a polydisperse colloidal dispersion is refluxed in the presence of a surface-active molecule, such as alkanethiol. The mDR method involved a small modification in the procedure, wherein refluxing was performed with an alkanethiol and a tetra-alkylammonium bromide surfactant. This minor modification led to a dramatic change in the final particle size distributions, giving access to nanoparticles in the <3 nm size regime; this was not possible with the traditional DR process. Bromide ions, which are present during refluxing, proved to be an important ingredient in the modification process. These bromide ions are revealed to act as etchants, resulting in ultra-small nanoparticles. All transition metal nanoparticles investigated displayed catalytic activity in the reduction reaction of p-nitro phenol. Pd nanoparticles, synthesized by a modified digestive ripening method, exhibited the best catalytic activity among the systems investigated.

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