Unified model of loop quantum gravity and matter

We reconsider the unified model of gravitation and Yang--Mills interactions proposed by Chakraborty and Peld\'an, in the light of recent formal developments in loop quantum gravity. In particular, we show that one can promote the Hamiltonian constraint of the unified model to a well defined anomaly-free quantum operator using the techniques introduced by Thiemann, at least for the Euclidean theory. The Lorentzian version of the model can be consistently constructed, but at the moment appears to yield a correct weak field theory only under restrictive assumptions, and its quantization appears problematic.Comment: 4 pages, dedicated to Michael P. Ryan on the occasion of his sixtieth birthda

Emissivity coatings for low-temperature space radiators Quarterly progress report no. 1, 1 Jul. - 30 Sep. 1965

Emissivity coatings for low temperature spacecraft radiator

Fluctuating Topological Defects in 2D Liquids: Heterogeneous Motion and Noise

We measure the defect density as a function of time at different temperatures in simulations of a two dimensional system of interacting particles. Just above the solid to liquid transition temperature, the power spectrum of the defect fluctuations shows a 1/f signature, which crosses over to a white noise signature at higher temperatures. When 1/f noise is present, the 5-7 defects predominately form string like structures, and the particle trajectories show a 1D correlated motion that follows the defect strings. At higher temperatures this heterogeneous motion is lost. We demonstrate this heterogeneity both in systems interacting with a short ranged screened Coulomb interaction, as well as in systems with a long range logarithmic interaction between the particles.Comment: 4 pages, 5 postscript figure

Study of an attitude reference system utilizing an electrically suspended gyro final report, 1 aug. 1964 - 31 mar. 1965

Miniature electrically suspended gyroscope for spacecraft attitude reference syste

Anisotropic Sliding Dynamics, Peak Effect, and Metastability in Stripe Systems

A variety of soft and hard condensed matter systems are known to form stripe patterns. Here we use numerical simulations to analyze how such stripe states depin and slide when interacting with a random substrate and with driving in different directions with respect to the orientation of the stripes. Depending on the strength and density of the substrate disorder, we find that there can be pronounced anisotropy in the transport produced by different dynamical flow phases. We also find a disorder-induced "peak effect" similar to that observed for superconducting vortex systems, which is marked by a transition from elastic depinning to a state where the stripe structure fragments or partially disorders at depinning. Under the sudden application of a driving force, we observe pronounced metastability effects similar to those found near the order-disorder transition associated with the peak effect regime for three-dimensional superconducting vortices. The characteristic transient time required for the system to reach a steady state diverges in the region where the flow changes from elastic to disordered. We also find that anisotropy of the flow persists in the presence of thermal disorder when thermally-induced particle hopping along the stripes dominates. The thermal effects can wash out the effects of the quenched disorder, leading to a thermally-induced stripe state. We map out the dynamical phase diagram for this system, and discuss how our results could be explored in electron liquid crystal systems, type-1.5 superconductors, and pattern-forming colloidal assemblies.Comment: 18 pages, 22 postscript figure

CELSS Transportation Analysis

Regenerative life support systems based on the use of biological material was considered for inclusion in manned spacecraft. Biological life support systems are developed in the controlled ecological life support system (CELSS) program. Because of the progress achieved in the CELSS program, it is determined which space missions may profit from use of the developing technology. Potential transportation cost savings by using CELSS technology for selected future manned space missions was evaluated. Six representative missions were selected which ranged from a low Earth orbit mission to those associated with asteroids and a Mars sortie. The crew sizes considered varied from four persons to five thousand. Other study parameters included mission duration and life support closure percentages, with the latter ranging from complete resupply of consumable life support materials to 97% closure of the life support system. The analytical study approach and the missions and systems considered, together with the benefits derived from CELSS when applicable are described

Structural Transitions, Melting, and Intermediate Phases for Stripe and Clump Forming Systems

We numerically examine the properties of a two-dimensional system of particles which have competing long range repulsive and short range attractive interactions as a function of density and temperature. For increasing density, there are well defined transitions between a low density clump phase, an intermediate stripe phase, an anticlump phase, and a high density uniform phase. To characterize the transitions between these phases we propose several measures which take into account the different length scales in the system. For increasing temperature, we find an intermediate phase that is liquid-like on the short length scale of interparticle spacing but solid-like on the larger length scale of the clump, stripe, or anticlump pattern. This intermediate phase persists over the widest temperature range in the stripe state when the local particle lattice within an individual stripe melts well below the temperature at which the entire stripe structure breaks down, and is characterized by intra-stripe diffusion of particles without inter-stripe diffusion. This is followed at higher temperatures by the onset of inter-stripe diffusion in an anisotropic diffusion phase, and then by breakup of the stripe structure. We identify the transitions between these regimes through diffusion, specific heat, and energy fluctuation measurements, and find that within the intra-stripe liquid regime, the excess entropy goes into disordering the particle arrangements within the stripe rather than affecting the stripe structure itself. The clump and anticlump phases also show multiple temperature-induced diffusive regimes which are not as pronounced as those of the stripe phase.Comment: 13 pages, 17 postscript figure

The Synthesis of Prilocaine from Toluene

Prilocaine hydrochloride is a local anesthetic from the amide family. Commonly used in dental work as an injected topical anesthetic, prilocaine temporarily numbs and inhibits nerve endings in soft tissue for up to two hours, leading to a decrease in pain. The synthesis of prilocaine is a four step process which starts with a mono-nitration of toluene. The nitrated product is then reduced by catalytic hydrogenation to produce toluidine. O-toluidine hydrochloride is isolated by treating toluidine with acetic anhydride followed by an extraction for purification. The acetylated product was then mixed with 2-choloropropionyl chloride to produce the final prilocaine product. In an effort to make the reaction more environmentally friendly, diethyl ether was replaced by methoxycyclopentane in the mono-nitration of toluene

The development of an advanced system to cool a man in a pressure suit

Conductive cooling system for cooling man in pressurized space sui