Physical/chemical closed-loop water-recycling

Water needs, water sources, and means for recycling water are examined in terms appropriate to the water quality requirements of a small crew and spacecraft intended for long duration exploration missions. Inorganic, organic, and biological hazards are estimated for waste water sources. Sensitivities to these hazards for human uses are estimated. The water recycling processes considered are humidity condensation, carbon dioxide reduction, waste oxidation, distillation, reverse osmosis, pervaporation, electrodialysis, ion exchange, carbon sorption, and electrochemical oxidation. Limitations and applications of these processes are evaluated in terms of water quality objectives. Computerized simulation of some of these chemical processes is examined. Recommendations are made for development of new water recycling technology and improvement of existing technology for near term application to life support systems for humans in space. The technological developments are equally applicable to water needs on Earth, in regions where extensive water recycling is needed or where advanced water treatment is essential to meet EPA health standards

A fast algorithm for backbones

A matching algorithm for the identification of backbones in percolation problems is introduced. Using this procedure, percolation backbones are studied in two- to five-dimensional systems containing 1.7x10^7 sites, two orders of magnitude larger than was previously possible using burning algorithms.Comment: 8 pages, 6 .eps figures. Uses epsfig and ijmpc.sty (included). To appear in Int. J. Mod. Phys.

On Nonconservative Stability Problems of Elastic Systems with Slight Damping

Equilibrium stability of linear two degree of freedom system with slight viscous damping subjected to nonconservative loadin

Statistical Laws and Mechanics of Voronoi Random Lattices

We investigate random lattices where the connectivities are determined by the Voronoi construction, while the location of the points are the dynamic degrees of freedom. The Voronoi random lattices with an associated energy are immersed in a heat bath and investigated using a Monte Carlo simulation algorithm. In thermodynamic equilibrium we measure coordination number distributions and test the Aboav-Weaire and Lewis laws.Comment: 14 pages (figures not included), LaTeX, HLRZ-26/9

Identification of an interchromosomal compartment by polymerization of nuclear-targeted vimentin

A number of structural and functional subnuclear compartments have been described, including regions exclusive of chromosomes previously hypothesized to form a reactive nuclear space. We have now explored this accessible nuclear space and interchromosomal nucleoplasmic domains experimentally using Xenopus vimentin engineered to contain a nuclear localization signal (NLS-vimentin). In stably transfected human cells incubated at 37°C, the NLS-vimentin formed a restricted number of intranuclear speckles. At 28°C, the optimal temperature for assembly of the amphibian protein, NLSvimentin progressively extended with time out from the speckles into strictly orientated intranuclear filamentous arrays. This enabled us to observe the development of a system of interconnecting channel-like areas. Quantitative analysis based on 3-D imaging microscopy revealed that these arrays were localized almost exclusively outside of chromosome territories. During mitosis the filaments disassembled and dispersed throughout the cytoplasm, while in anaphase-telophase the vimentin was recruited back into the nucleus and reassembled into filaments at the chromosome surfaces, in distributions virtually identical to those observed in the previous interphase. The filaments also colocalized with specific nuclear RNAs, coiled bodies and PML bodies, all situated outside of chromosome territories, thereby interlinking these structures. This strongly implies that these nuclear entities coexist in the same interconnected nuclear compartment. The assembling NLS-vimentin is restricted to and can be used to delineate, at least in part, the formerly proposed reticular interchromosomal domain compartment (ICD). The properties of NLS-vimentin make it an excellent tool for performing structural and functional studies on this compartment

Model of mobile agents for sexual interactions networks

We present a novel model to simulate real social networks of complex interactions, based in a granular system of colliding particles (agents). The network is build by keeping track of the collisions and evolves in time with correlations which emerge due to the mobility of the agents. Therefore, statistical features are a consequence only of local collisions among its individual agents. Agent dynamics is realized by an event-driven algorithm of collisions where energy is gained as opposed to granular systems which have dissipation. The model reproduces empirical data from networks of sexual interactions, not previously obtained with other approaches.Comment: 6 pages, 8 figure

Correlated electrons systems on the Apollonian network

Strongly correlated electrons on an Apollonian network are studied using the Hubbard model. Ground-state and thermodynamic properties, including specific heat, magnetic susceptibility, spin-spin correlation function, double occupancy and one-electron transfer, are evaluated applying direct diagonalization and quantum Monte Carlo. The results support several types of magnetic behavior. In the strong-coupling limit, the quantum anisotropic spin 1/2 Heisenberg model is used and the phase diagram is discussed using the renormalization group method. For ferromagnetic coupling, we always observe the existence of long-range order. For antiferromagnetic coupling, we find a paramagnetic phase for all finite temperatures.Comment: 7 pages, 8 figure

Discrete Fracture Model with Anisotropic Load Sharing

A two-dimensional fracture model where the interaction among elements is modeled by an anisotropic stress-transfer function is presented. The influence of anisotropy on the macroscopic properties of the samples is clarified, by interpolating between several limiting cases of load sharing. Furthermore, the critical stress and the distribution of failure avalanches are obtained numerically for different values of the anisotropy parameter $\alpha$ and as a function of the interaction exponent $\gamma$. From numerical results, one can certainly conclude that the anisotropy does not change the crossover point $\gamma_c=2$ in 2D. Hence, in the limit of infinite system size, the crossover value $\gamma_c=2$ between local and global load sharing is the same as the one obtained in the isotropic case. In the case of finite systems, however, for $\gamma\le2$, the global load sharing behavior is approached very slowly