Spaceflight tracking and data network operational reliability computer output for MTBF and availability. Appendix V to CSC-1-395

Tables of data are provided to show the availability of Skylab data to selected ground stations during the phases of Skylab preflight, Skylab unmanned condition, and Skylab manned condition. The mean time between failure (MTBF) of the same Skylab functions is tabulated for the selected ground stations. All reliability data are based on a 90 percent confidence interval

Spatiotemporal Effects of Transport and Network Topology in Biological Systems

Emergent biological phenomena, although observed experimentally, are often not easily characterized or understood. Biological systems are often comprised of many interacting components, which may yield highly complex dynamics. A thorough understanding of these systems often requires a multi-faceted approach involving both experimental and computational techniques. Computer simulation allows for precise definition of system components and facilitates a wider exploration of the system parameter space, often leading to accelerated scientific discovery. In this thesis, we apply stochastic simulation methods to characterize the spatiotemporal behavior of three distinct biological systems. We first explore the role of spatial confinement and diffusion in a bistable reaction network with positive feedback. We find that confined systems with high molecular mobility promote the active steady state, and stochastic switching occurs unidirectionally by nucleation and growth of single active clusters. The results provide a general framework for studying geometry and diffusion in positive feedback networks, and suggest that confinement can be used to initiate the formation of localized active clusters of molecules that then propagate to activate a system. Next, we study transport properties of single molecular motors traversing cytoskeletal networks with random filament configuration. We find that systems containing few, long filaments exhibit slow and highly variable transport. Particular filaments are capable of having an outsized influence on first-passage times by acting as lynchpins that transport motors to and from regions of the system that act as traps that promote extended occupancy. Finally, we use two distinct models to explore the dynamics of protein organization along an actomyosin ring. We find that a positive feedback circuit can be used to establish and maintain polarized protein distributions, and clustering is suppressed by endocytosis and fast diffusion. In the absence of positive feedback and dissociation from the ring, we find that slow association of large patches leads to clustered distributions of higher variability. These results suggest that homogeneous spatial distribution of proteins in mature actomyosin rings may depend on frequent association of small protein clusters. Taken collectively, these findings suggest that stochastic computational modeling can facilitate the elucidation of key mechanistic features of emergent biological phenomena

Circularly polarized microwaves for magnetic resonance study in the GHz range: application to nitrogen-vacancy in diamonds

The ability to create time-dependent magnetic fields of controlled polarization is essential for many experiments with magnetic resonance. We describe a microstrip circuit that allows us to generate strong magnetic field at microwave frequencies with arbitrary adjusted polarization. The circuit performance is demonstrated by applying it to an optically detected magnetic resonance and Rabi nutation experiments in nitrogen-vacancy color centers in diamond. Thanks to high efficiency of the proposed microstrip circuit and degree of circular polarization of 85% it is possible to address the specific spin states of a diamond sample using a low power microwave generator.Comment: 4 pages, 7 figures, nitrogen-vacancy, microwave circular polarization, spin-state addressin

Influence of Extensive Management on Botanical Composition of Permanent Meadow Sward

The aim of undertaken investigations was to find the possibilities of grassland management with special respect to the biodiversity and the landscape conservation. Changes in botanical composition of the meadow sward against a background of different mowing utilization were examined on the semi-natural meadows situated on the peat-mursh soil in Masurian Landscape Park (north-east Poland). The areas mown with biennial pause and completely turned off from uses followed gradual simplifying of species composition and increasing of bog species participation. Results show on advisability of passing one harvest each year or with one-year pauses

Finite-difference time-domain analysis of ELF radio wave propagation in the spherical Earth–ionosphere waveguide and its validation based on analytical solutions

The finite-difference time-domain (FDTD) model of electromagnetic wave propagation in the Earth–ionosphere cavity was developed under assumption of an axisymmetric system, solving the reduced Maxwell equations in a 2D spherical coordinate system. The model was validated on different conductivity profiles for the electric and magnetic field components for various locations on Earth along the meridian. The characteristic electric and magnetic altitudes, phase velocity, and attenuation rate were calculated. We compared the results of numerical and analytical calculations and found good agreement between them. The undertaken FDTD modeling enables us to analyze the Schumann resonances and the propagation of individual lightning discharges occurring at various distances from the receiver. The developed model is particularly useful when analyzing ELF measurements.</p

Dendrimer Structure Diversity and Tailorability as a Way to Fight Infectious Diseases

Dendrimers represent a distinct class of polymers—highly branched and uniform, with a relatively small size when compared to their mass. They are composed of the core, from which branched polymeric dendrons diverge and they are end‐capped with selected terminal groups. Recently, dendrimers have attracted considerable attention from medicinal chemists, mostly due to their well‐defined and easy‐to‐modify structure. This chapter aims to compile dendrimer applications and activities especially for prevention and fighting off infections caused by bacteria and fungi, viruses, and parasites/protozoa. Our goal in this review is to discuss selected modifications of dendrimers of potential value for pharmaceutical chemistry

Spaceflight tracking and data network operational reliability assessment for Skylab

Data on the spaceflight communications equipment status during the Skylab mission were subjected to an operational reliability assessment. Reliability models were revised to reflect pertinent equipment changes accomplished prior to the beginning of the Skylab missions. Appropriate adjustments were made to fit the data to the models. The availabilities are based on the failure events resulting in the stations inability to support a function of functions and the MTBF's are based on all events including 'can support' and 'cannot support'. Data were received from eleven land-based stations and one ship