NASA ground terminal communication equipment automated fault isolation expert systems

The prototype expert systems are described that diagnose the Distribution and Switching System I and II (DSS1 and DSS2), Statistical Multiplexers (SM), and Multiplexer and Demultiplexer systems (MDM) at the NASA Ground Terminal (NGT). A system level fault isolation expert system monitors the activities of a selected data stream, verifies that the fault exists in the NGT and identifies the faulty equipment. Equipment level fault isolation expert systems are invoked to isolate the fault to a Line Replaceable Unit (LRU) level. Input and sometimes output data stream activities for the equipment are available. The system level fault isolation expert system compares the equipment input and output status for a data stream and performs loopback tests (if necessary) to isolate the faulty equipment. The equipment level fault isolation system utilizes the process of elimination and/or the maintenance personnel's fault isolation experience stored in its knowledge base. The DSS1, DSS2 and SM fault isolation systems, using the knowledge of the current equipment configuration and the equipment circuitry issues a set of test connections according to the predefined rules. The faulty component or board can be identified by the expert system by analyzing the test results. The MDM fault isolation system correlates the failure symptoms with the faulty component based on maintenance personnel experience. The faulty component can be determined by knowing the failure symptoms. The DSS1, DSS2, SM, and MDM equipment simulators are implemented in PASCAL. The DSS1 fault isolation expert system was converted to C language from VP-Expert and integrated into the NGT automation software for offline switch diagnoses. Potentially, the NGT fault isolation algorithms can be used for the DSS1, SM, amd MDM located at Goddard Space Flight Center (GSFC)

Breathing FIRE: How Stellar Feedback Drives Radial Migration, Rapid Size Fluctuations, and Population Gradients in Low-Mass Galaxies

We examine the effects of stellar feedback and bursty star formation on low-mass galaxies ($M_{\rm star}=2\times10^6-5\times10^{10}{\rm M_{\odot}}$) using the FIRE (Feedback in Realistic Environments) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate $\sim1{\rm\,kpc}$ within their first $100 {\rm\,Myr}$, and (2) gas outflows/inflows drive strong fluctuations in the global potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies' effective radii can fluctuate by factors of $>2$ over $\sim200 {\rm\,Myr}$, and these rapid size fluctuations can account for much of the observed scatter in radius at fixed $M_{\rm star}.$ Second, the cumulative effects of many outflow/infall episodes steadily heat stellar orbits, causing old stars to migrate outward most strongly. This age-dependent radial migration mixes---and even inverts---intrinsic age and metallicity gradients. Thus, the galactic-archaeology approach of calculating radial star-formation histories from stellar populations at $z=0$ can be severely biased. These effects are strongest at $M_{\rm star}\approx10^{7-9.6}{\rm M_{\odot}}$, the same regime where feedback most efficiently cores galaxies. Thus, detailed measurements of stellar kinematics in low-mass galaxies can strongly constrain feedback models and test baryonic solutions to small-scale problems in $\Lambda$CDM.Comment: Accepted to ApJ (820, 131) with minor revisions from v1. Figure 4 now includes dark matter. Main results in Figures 7 and 1

Close Pairs as Proxies for Galaxy Cluster Mergers

Galaxy cluster merger statistics are an important component in understanding the formation of large-scale structure. Unfortunately, it is difficult to study merger properties and evolution directly because the identification of cluster mergers in observations is problematic. We use large N-body simulations to study the statistical properties of massive halo mergers, specifically investigating the utility of close halo pairs as proxies for mergers. We examine the relationship between pairs and mergers for a wide range of merger timescales, halo masses, and redshifts (0<z<1). We also quantify the utility of pairs in measuring merger bias. While pairs at very small separations will reliably merge, these constitute a small fraction of the total merger population. Thus, pairs do not provide a reliable direct proxy to the total merger population. We do find an intriguing universality in the relation between close pairs and mergers, which in principle could allow for an estimate of the statistical merger rate from the pair fraction within a scaled separation, but including the effects of redshift space distortions strongly degrades this relation. We find similar behavior for galaxy-mass halos, making our results applicable to field galaxy mergers at high redshift. We investigate how the halo merger rate can be statistically described by the halo mass function via the merger kernel (coagulation), finding an interesting environmental dependence of merging: halos within the mass resolution of our simulations merge less efficiently in overdense environments. Specifically, halo pairs with separations less than a few Mpc/h are more likely to merge in underdense environments; at larger separations, pairs are more likely to merge in overdense environments.Comment: 12 pages, 9 figures; Accepted for publication in ApJ. Significant additions to text and two figures changed. Added new findings on the universality of pair mergers and added analysis of the effect of FoF linking length on halo merger

The Clustering of Massive Halos

The clustering properties of dark matter halos are a firm prediction of modern theories of structure formation. We use two large volume, high-resolution N-body simulations to study how the correlation function of massive dark matter halos depends upon their mass and formation history. We find that halos with the lowest concentrations are presently more clustered than those of higher concentration, the size of the effect increasing with halo mass; this agrees with trends found in studies of lower mass halos. The clustering dependence on other characterizations of the full mass accretion history appears weaker than the effect with concentration. Using the integrated correlation function, marked correlation functions, and a power-law fit to the correlation function, we find evidence that halos which have recently undergone a major merger or a large mass gain have slightly enhanced clustering relative to a randomly chosen population with the same mass distribution.Comment: 10 pages, 8 figures; text improved, references and one figure added; accepted for publication in Ap

Phospholemman, a Single-Span Membrane Protein, Is an Accessory Protein of Na,K-ATPase in Cerebellum and Choroid Plexus

Phospholemman (FXYD1) is a homolog of the Na,K-ATPase γ subunit (FXYD2), a small accessory protein that modulates ATPase activity. Here we show that phospholemman is highly expressed in selected structures in the CNS. It is most abundant in cerebellum, where it was detected in the molecular layer, in Purkinje neurons, and in axons traversing the granule cell layer. Phospholemman was particularly enriched in choroid plexus, the organ that secretes CSF in the ventricles, where it colocalized with Na,K-ATPase in the apical membrane. It was also enriched, with Na,K-ATPase, in certain tanycytes or ependymal cells of the ventricle wall. Two different experimental approaches demonstrated that phospholemman physically associated with the Na,K-ATPase in cerebellum and choroid plexus: the proteins copurified after detergent treatment and co-immunoprecipitated from solubilized crude membranes using either anti-phospholemman or anti-Na,K-ATPase antibodies. Phospholemman antibodies precipitated all three Na,K-ATPase α subunit isoforms (α1–α3) from cerebellum, indicating that the interaction is not specific to a particular α isoform and consistent with the presence of phospholemman in both neurons and glia. Antibodies against the C-terminal domain of phospholemman reduced Na,K-ATPase activityin vitro without effect on Na+affinity. At least two other FXYD family members have been detected in the CNS, suggesting that additional complexity of sodium pump regulation will be found

Characterization of a historically nutrient enriched marsh ecosystem : Yorktown Creek, Yorktown, Virginia

In this report, we summarize our initial findings of a nutrient enriched aquatic ecosystem prior to relaxation of sewage input. The studies reported were directed toward characterizing the system prior to relaxation and to begin xperimental studies to accomplish our general objectives

The first report of Aelurostrongylus falciformis in Norwegian badgers (Meles meles)

The first report of Aelurostrongylus falciformis (Schlegel 1933) in Fennoscandian badgers is described. Routine parasitological examination of nine Norwegian badgers, at the National Veterinary Institute during 2004 and 2005, identified A. falciformis in the terminal airways of five of the animals. The first stage larvae (L1) closely resembled, in size and morphology, those of Angiostrongylus vasorum (Baillet 1866). The diagnosis for both A. falciformis and A. vasorum is frequently based on the identification of L1 in faeces or sputum. The potential for misclassification of an A. falciformis infection as A. vasorum, where larval identification is the only diagnostic method used, is discussed

Analysis of the stability of InGaN/GaN multiquantum wells against ion beam intermixing

Ion-induced damage and intermixing was evaluated in InGaN/GaN multi-quantum wells (MQWs) using 35 keV N+ implantation at room temperature. In situ ion channeling measurements show that damage builds up with a similar trend for In and Ga atoms, with a high threshold for amorphization. The extended defects induced during the implantation, basal and prismatic stacking faults, are uniformly distributed across the quantum well structure. Despite the extremely high fluences used (up to 4 ×1016 cm-2), the InGaN MQWs exhibit a high stability against ion beam mixing

Metodologia para criopreservação de sementes de espécies florestais nativas.

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