The Feasibility of the Disturbance Accommodating Controller for Precision Antenna Pointing

The objective of this study is to investigate the feasibility of a pointing (position loop) controller for the NASA-JPL Deep Space Network (DSN) antennas using the Disturbance Accommodating Control (DAC) theory. A model that includes state dependent disturbances was developed, and an example demonstrating the noise estimator is presented as an initial phase in the controller design. The goal is to improve pointing accuracy by the removal of the systematic errors caused by the antenna misalignment as well as sensor noise and random wind and thermal disturbances. Preliminary simulation results show that the DAC technique is successful in both cancelling the imposed errors and maintaining an optimal control policy

Cooperative Restoration Programs in Critical Habitats in the Upper South Carolina Coastal Region

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

Second NASA Technical Interchange Meeting (TIM): Advanced Technology Lifecycle Analysis System (ATLAS) Technology Tool Box (TTB)

The Advanced Technology Lifecycle Analysis System (ATLAS), a spreadsheet analysis tool suite, applies parametric equations for sizing and lifecycle cost estimation. Performance, operation, and programmatic data used by the equations come from a Technology Tool Box (TTB) database. In this second TTB Technical Interchange Meeting (TIM), technologists, system model developers, and architecture analysts discussed methods for modeling technology decisions in spreadsheet models, identified specific technology parameters, and defined detailed development requirements. This Conference Publication captures the consensus of the discussions and provides narrative explanations of the tool suite, the database, and applications of ATLAS within NASA s changing environment

A solid-reagent dispenser for use in the azocoll protease assay (and other insoluble substrate analyses).

A solid-reagent dispenser for use in the azocoll protease assay (and other insoluble substrate analyses)

A Signal Detection Theoretic Analysis of the Carney Model of Auditory Processing

Abstract: Historically, signa[ detection theory (SDT) applied "outside" the ear has not provided valid estimates of the performance measured in psychophysical experiments. Our previous work, in which SDT wm applied at the output of each stage of the Auditory Image Model (AIM) (1), has indicated that this integrated approach affords theoretical performance predictions that are more closely matched to experimental data than previous approaches (2). In this paper, we describe the results obtained when a similar approach is applied to the output of the Camey model of auditory processing (3). Our results indicate that for a simultaneous masking task, when it is assumed that all parameters of the input signal are known, the performance predictions obtained from SDT integrated with AIM and the Carney model are similar at the neural firing stage, and both over-predict experimental measures. However, when it is assumed that the phase of the sinusoid is unknown, the integrated approach provides performance estimates that are fairly close to the performance levels observed experimentally

Top A_FB at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets

We consider the top forward-backward (FB) asymmetry at the Tevatron and top charge asymmetry at the LHC within chiral U(1)^\prime models with flavor-dependent U(1)^\prime charges and flavored Higgs fields, which were introduced in the ref. [65]. The models could enhance not only the top forward-backward asymmetry at Tevatron, but also the top charge asymmetry at LHC, without too large same-sign top pair production rates. We identify parameter spaces for the U(1)^\prime gauge boson and (pseudo)scalar Higgs bosons where all the experimental data could be accommodated, including the case with about 125 GeV Higgs boson, as suggested recently by ATLAS and CMS.Comment: 11 pages, 6 figures, figures and discussion adde

Coordination of growth rate, cell cycle, stress response, and metabolic activity in

We studied the relationship between growth rate and genome-wide gene expression, cell cycle progression, and glucose metabolism in 36 steady-state continuous cultures limited by one of six different nutrients (glucose, ammonium, sulfate, phosphate, uracil, or leucine). The expression of more than one quarter of all yeast genes is linearly correlated with growth rate, independent of the limiting nutrient. The subset of negatively growth-correlated genes is most enriched for peroxisomal functions, whereas positively correlated genes mainly encode ribosomal functions. Many (not all) genes associated with stress response are strongly correlated with growth rate, as are genes that are periodically expressed under conditions of metabolic cycling. We confirmed a linear relationship between growth rate and the fraction of the cell population in the G0/G1 cell cycle phase, independent of limiting nutrient. Cultures limited by auxotrophic requirements wasted excess glucose, whereas those limited on phosphate, sulfate, or ammonia did not; this phenomenon (reminiscent of the “Warburg effect ” in cancer cells) was confirmed in batch cultures. Using an aggregate of gene expression values, we predict (in both continuous and batch cultures) an “instantaneous growth rate. ” This concept is useful in interpreting the system-level connections among growth rate, metabolism, stress, and the cell cycle

Effect of surfactants on the thermoresponse of PNIPAM investigated in the brush geometry

Hypothesis: Anionic surfactants have been reported to interact with poly(N-isopropyl acrylamide) (PNIPAM), suppressing its thermoresponse. Scattering and NMR studies of the anionic sodium dodecylsulfate (SDS) system propose that the PNIPAM-surfactant interaction is purely hydrophobic. However, prior phenomenological investigations of a range of surfactant identities (anionic, cationic, nonionic) show that only anionic surfactants affect the thermoresponse and conformation of PNIPAM, implying that the hydrophilic head–group also contributes. Crucially, the phenomenological experiments do not measure the affinity of the tested surfactants to the polymer, only their effect on its behaviour. Experiments: We study the adsorption of six surfactants within a planar PNIPAM brush system, elucidating the polymer conformation, thermoresponse, and surfactant adsorption kinetics using ellipsometry, neutron reflectometry (NR), optical reflectometry and the quartz crystal microbalance technique. NR is used to measure the distribution of surfactants within the brush. Findings: We find that only anionic surfactants modify the structure and thermoresponse of PNIPAM, with the greater affinity of anionic surfactants for PNIPAM (relative to cationic and nonionic surfactants) being the primary reason for this behaviour. These results show that the surfactant head–group has a more critical role in mediating PNIPAM-surfactant interaction than previously reported. Taking inspiration from prior molecular dynamics work on the PEO-surfactant system, we propose an interaction mechanism for PNIPAM and SDS that reconciles evidence for hydrophobic interaction with the observed head–group-dependent affinity.</p

Top quark forward-backward asymmetry in R-parity violating supersymmetry

The interaction of bottom squark-mediated top quark pair production, occurring in the R-parity violating minimal supersymmetric standard model (MSSM), is proposed as an explanation of the anomalously large $t\bar{t}$ forward-backward asymmetry (FBA) observed at the Tevatron. We find that this model can give a good fit to top quark data, both the inclusive and invariant mass-dependent asymmetries, while remaining consistent (at the 2-$\sigma$ level) with the total and differential production cross-sections. The scenario is challenged by strong constraints from atomic parity violation (APV), but we point out an extra diagram for the effective down quark-Z vertex, involving the same coupling constant as required for the FBA, which tends to weaken the APV constraint, and which can nullify it for reasonable values of the top squark masses and mixing angle. Large contributions to flavor-changing neutral currents can be avoided if only the third generation of sparticles is light.Comment: 24 pages, 7 figures. v3: included LHC top production cross section data; model still consistent at 2 sigma leve