Life science payloads planning study integration facility survey results

The integration facility survey effort described is structured to examine the facility resources needed to conduct life science payload (LSP) integration checkout activities at NASA-JSC. The LSP integration facility operations and functions are defined along with the LSP requirements for facility design. A description of available JSC life science facilities is presented and a comparison of accommodations versus requirements is reported

Markov Chain Modeling of Polymer Translocation Through Pores

We solve the Chapman-Kolmogorov equation and study the exact splitting probabilities of the general stochastic process which describes polymer translocation through membrane pores within the broad class of Markov chains. Transition probabilities which satisfy a specific balance constraint provide a refinement of the Chuang-Kantor-Kardar relaxation picture of translocation, allowing us to investigate finite size effects in the evaluation of dynamical scaling exponents. We find that (i) previous Langevin simulation results can be recovered only if corrections to the polymer mobility exponent are taken into account and that (ii) the dynamical scaling exponents have a slow approach to their predicted asymptotic values as the polymer's length increases. We also address, along with strong support from additional numerical simulations, a critical discussion which points in a clear way the viability of the Markov chain approach put forward in this work.Comment: 17 pages, 5 figure

Symbiotic stars in X-rays III: Suzaku observations

We describe the X-ray emission as observed with Suzaku from five symbiotic stars that we selected for deep Suzaku observations after their initial detection with ROSAT, ASCA and Swift. We find that the X-ray spectra of all five sources can be adequately fit with absorbed, optically thin thermal plasma models, with either single- or multi-temperature plasmas. These models are compatible with the X-ray emission originating in the boundary layer between an accretion disk and a white dwarf. The high plasma temperatures of kT$~>3$ keV for all five targets were greater than expected for colliding winds. Based on these high temperatures, as well as previous measurements of UV variability and UV luminosity, and the large amplitude of X-ray flickering in 4 Dra, we conclude that all five sources are accretion-powered through predominantly optically thick boundary layers. Our X-ray data allow us to observe a small, optically thin portion of the emission from these boundary layers. Given the time between previous observations and these observations, we find that the intrinsic X-ray flux and the intervening absorbing column can vary by factors of three or more on a time scale of years. However, the location of the absorber and the relationship between changes in accretion rate and absorption are still elusive.Comment: 14 pages, 3 figures and 3 tables. Accepted to published 04/15/2016. arXiv admin note: substantial text overlap with arXiv:1505.0063

Vortices in a cylinder: Localization after depinning

Edge effects in the depinned phase of flux lines in hollow superconducting cylinder with columnar defects and electric current along the cylinder are investigated. Far from the ends of the cylinder vortices are distributed almost uniformly (delocalized). Nevertheless, near the edges these free vortices come closer together and form well resolved dense bunches. A semiclassical picture of this localization after depinning is described. For a large number of vortices their density $\rho(x)$ has square root singularity at the border of the bunch ($\rho(x)$ is semicircle in the simplest case). However, by tuning the strength of current, the various singular regimes for $\rho(x)$ may be reached. Remarkably, this singular behaviour reproduces the phase transitions discussed during the past decade within the random matrix regularization of 2d-Gravity.Comment: 4 pages, REVTEX, 2 eps figure

Defect-Mediated Emulsification in Two Dimensions

We consider two dimensional dispersions of droplets of isotropic phase in a liquid with an XY-like order parameter, tilt, nematic, and hexatic symmetries being included. Strong anchoring boundary conditions are assumed. Textures for a single droplet and a pair of droplets are calculated and a universal droplet-droplet pair potential is obtained. The interaction of dispersed droplets via the ordered phase is attractive at large distances and repulsive at short distances, which results in a well defined preferred separation for two droplets and topological stabilization of the emulsion. This interaction also drives self-assembly into chains. Preferred separations and energy barriers to coalescence are calculated, and effects of thermal fluctuations and film thickness are discussed.Comment: revtex4, 13 pages, 12 figure

Chern-Simons Quantization of (2+1)-Anti-De Sitter Gravity on a Torus

Chern-Simons formulation of 2+1 dimensional Einstein gravity with a negative cosmological constant is investigated when the spacetime has the topology $R\times T^{2}$. The physical phase space is shown to be a direct product of two sub-phase spaces each of which is a non-Hausdorff manifold plus a set with nonzero codimensions. Spacetime geometrical interpretation of each point in the phase space is also given and we explain the 1 to 2 correspondence with the ADM formalism from the geometrical viewpoint. In quantizing this theory, we construct a "modified phase space" which is a cotangnt bundle on a torus. We also provide a modular invariant inner product and investigate the relation to the quantum theory which is directly related to the spinor representation of the ADM formalism. (This paper is the revised version of a previous paper(hep-th/9312151). The wrong discussion on the topology of the phase space is corrected.)Comment: latex 28 page

Entwined Paths, Difference Equations and the Dirac Equation

Entwined space-time paths are bound pairs of trajectories which are traversed in opposite directions with respect to macroscopic time. In this paper we show that ensembles of entwined paths on a discrete space-time lattice are simply described by coupled difference equations which are discrete versions of the Dirac equation. There is no analytic continuation, explicit or forced, involved in this description. The entwined paths are `self-quantizing'. We also show that simple classical stochastic processes that generate the difference equations as ensemble averages are stable numerically and converge at a rate governed by the details of the stochastic process. This result establishes the Dirac equation in one dimension as a phenomenological equation describing an underlying classical stochastic process in the same sense that the Diffusion and Telegraph equations are phenomenological descriptions of stochastic processes.Comment: 15 pages, 5 figures Replacement 11/02 contains minor editorial change