Fractionation of distance in simulated space

Fractionation of distance in space environment simulatio

Deep Space Network information system architecture study

The purpose of this article is to describe an architecture for the Deep Space Network (DSN) information system in the years 2000-2010 and to provide guidelines for its evolution during the 1990s. The study scope is defined to be from the front-end areas at the antennas to the end users (spacecraft teams, principal investigators, archival storage systems, and non-NASA partners). The architectural vision provides guidance for major DSN implementation efforts during the next decade. A strong motivation for the study is an expected dramatic improvement in information-systems technologies, such as the following: computer processing, automation technology (including knowledge-based systems), networking and data transport, software and hardware engineering, and human-interface technology. The proposed Ground Information System has the following major features: unified architecture from the front-end area to the end user; open-systems standards to achieve interoperability; DSN production of level 0 data; delivery of level 0 data from the Deep Space Communications Complex, if desired; dedicated telemetry processors for each receiver; security against unauthorized access and errors; and highly automated monitor and control

Neuroanastomosis of orthotopically transplanted palmaris longus muscles

Palmaris longus (PML) muscles of rhesus monkeys were transplanted, with or without anastomosis of the median nerve, to the nerve stump of the autograft. Because PML autografts revascularize spontaneously, vascular anastomoses were not performed. Muscle fibers regenerated in all autografts with neuroanastomosis, but in only three of eight autografts without neuroanastomosis. Five autografts without neuroanastomosis were replaced by noncontractile connective tissue. Growth and differentiation of muscle fibers into three fiber types and development of capillarity were analyzed histochemically, and succinate oxidase activity of whole-muscle homogenates was determined. None of these measures reached values for control PML muscles within 100 days of transplantation. In comparison to control muscles, autografts had slower times to peak tension and less absolute tension, but similar tension per square centimeter of muscle fiber cross-sectional area. Monkey PML autografts with neuroanastomosis were similar in structure and function to cat extensor digitorum longus autografts that had not had neuroanastomosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50127/1/880020107_ftp.pd

Preliminary thermal-hydraulic design and predicted performance of the Clinch River Breeder Reactor core

The preliminary thermofluids design of the core assemblies of the Clinch River Breeder Reactor Plant (CRBRP) is presented along with the predicted performance for various plant operating conditions. The selected radial blanket assemblies shuffling scheme and the new approach adopted for fuel and blanket assemblies orificing is discussed. Relevant thermofluids parameters (assembly flow rate and mixed mean outlet temperature, fuel rod temperatures, fission gas plenum pressure, etc.) are presented. Highlights of a detailed uncertainties study performed are summarized. This preliminary analysis has shown that the CRBRP core behavior is compatible with design limits and requirements; future developments for a final analysis are outlined. (auth

A Novel Mechanism for Type-I Superconductivity in Neutron Stars

We suggest a mechanism that may resolve a conflict raised by Link between the precession of a neutron star and the standard picture in which its core is composed of a mixture of a neutron superfluid and a type-II proton superconductor. We will show that if there is a persistent, non-dissipating current running along the magnetic flux tubes, the force between magnetic flux tubes may be attractive, resulting in a type-I, rather than a type-II, superconductor. If this is the case, the conflict between the observed precession and the canonical estimation of the Landau-Ginzburg parameter (which suggests type II behaviour) will be automatically resolved. Such a current arises in some condensed matter systems and may also appear in QCD dense matter as a consequence of quantum anomalies. We calculate the interaction between two vortices carrying a current j and find a constraint on the magnitude of j where a superconductor is always type-I, even when the cannonical Landau-Ginzburg parameter indicates type-II behaviour. If this condition is met, the magnetic field is expelled from the superconducting regions of the neutron star leading to the formation of the intermediate state where alternating domains of superconducting matter and normal matter coexist. We further argue that even when the induced current is small the vortex Abrikosov lattice will nevertheless be destroyed due to the helical instability studied previously in many condensed matter systems. This would also resolve the apparent contradiction with the precession of the neutron stars. We also discuss some instances where anomalous induced current may play a crucial role, such as the neutron star kicks, pulsar glitches and the toroidal magnetic field.Comment: 10 pages, Additional arguments are given supporting the idea that the Abrikosov lattice will be destroyed in regions where longitudinal currents are induce

The Complex Energy Landscape of the Protein IscU

AbstractIscU, the scaffold protein for iron-sulfur (Fe-S) cluster biosynthesis in Escherichia coli, traverses a complex energy landscape during Fe-S cluster synthesis and transfer. Our previous studies showed that IscU populates two interconverting conformational states: one structured (S) and one largely disordered (D). Both states appear to be functionally important because proteins involved in the assembly or transfer of Fe-S clusters have been shown to interact preferentially with either the S or D state of IscU. To characterize the complex structure-energy landscape of IscU, we employed NMR spectroscopy, small-angle x-ray scattering (SAXS), and differential scanning calorimetry. Results obtained for IscU at pH 8.0 show that its S state is maximally populated at 25°C and that heating or cooling converts the protein toward the D state. Results from NMR and DSC indicate that both the heat- and cold-induced S→D transitions are cooperative and two-state. Low-resolution structural information from NMR and SAXS suggests that the structures of the cold-induced and heat-induced D states are similar. Both states exhibit similar 1H-15N HSQC spectra and the same pattern of peptidyl-prolyl peptide bond configurations by NMR, and both appear to be similarly expanded compared with the S state based on analysis of SAXS data. Whereas in other proteins the cold-denatured states have been found to be slightly more compact than the heat-denatured states, these two states occupy similar volumes in IscU