1,654 research outputs found

    Temporal and dimensional effects in evolutionary graph theory

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    The spread in time of a mutation through a population is studied analytically and computationally in fully-connected networks and on spatial lattices. The time, t_*, for a favourable mutation to dominate scales with population size N as N^{(D+1)/D} in D-dimensional hypercubic lattices and as N ln N in fully-connected graphs. It is shown that the surface of the interface between mutants and non-mutants is crucial in predicting the dynamics of the system. Network topology has a significant effect on the equilibrium fitness of a simple population model incorporating multiple mutations and sexual reproduction. Includes supplementary information.Comment: 6 pages, 4 figures Replaced after final round of peer revie

    Task-Specific Ionic Liquids for Mars Exploration (Green Chemistry for a Red Planet)

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    Ionic Liquids (ILs) are organic salts with low melting points that are liquid at or near room temperature. The combinations of available ions and task-specific molecular designability make them suitable for a huge variety of tasks. Because of their low flammability, low vapor pressure, and stability in harsh environments (extreme temperatures, hard vacuum) they are generally much safer and "greener" than conventional chemicals and are thus suitable for a wide range of applications that support NASA exploration goals. This presentation describes several of the ongoing applications that are being developed at MSFC

    Electron Neutrino and Antineutrino Appearance in the Full MINOS Data Sample

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    We report on v(e) and (v) over bar (e) appearance in v(mu) and (v) over bar (mu) beams using the full MINOS data sample. The comparison of these v(e) and (v) over bar (e) appearance data at a 735 km baseline with theta(13) measurements by reactor experiments probes delta, the theta(23) octant degeneracy, and the mass hierarchy. This analysis is the first use of this technique and includes the first accelerator long-baseline search for (v) over bar (mu) -\u3e (v) over bar (e). Our data disfavor 31% (5%) of the three-parameter space defined by delta, the octant of the theta(23), and the mass hierarchy at the 68% (90%) C.L. We measure a value of 2sin(2)(2 theta(13))sin(2)(theta(23)) that is consistent with reactor experiments. DOI: 10.1103/PhysRevLett.110.17180

    Effects of Convection During the Photodeposition of Polydiacetylene Thin Films

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    In this work, we describe a preliminary investigation of buoyancy-driven heat transfer during the growth of thin films from solution following exposure to ultraviolet (UV) light. Irradiation of the growth cell occurs at various directions relative to gravitational acceleration. Through numerical computations, the steady-state flow and temperature profiles are simulated during the course of light exposure. Light-induced polymerization accompanies a heat transfer process through a fairly complicated recirculating flow pattern. A scaling analysis shows that buoyancy-driven velocities only reduce by a factor of 10 for gravity levels as low as 10(exp -2)g(sub 0). Paley et al. observe what appears to be gravitationally sensitive particle development and inclusion in thin films using a photodeposition process. From this study it is clear that production of homogeneous thin films would have to occur in the environment of a complicated flow pattern of recirculation with a nonuniform temperature distribution. Indeed, even when irradiation occurs from the top of the cell, the most stable stratified cell orientation, defects remain in our films due to the persistence of buoyancy-driven convection. To achieve homogeneity, minimal scattering centers, and possible molecular order, photodeposition of polymer films by UV light exposure must proceed in a reduced-convection environment. Fluid mechanics simulations are useful for establishing gravitational sensitivity to this recently discovered process (patent # 5,451,433) for preparing thin films having quite promising nonlinear optical characteristics

    Study of quasielastic scattering using charged-current nu(mu)-iron interactions in the MINOS near detector

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    Kinematic distributions from an inclusive sample of 1.41 x 10(6) charged-current nu(mu) interactions on iron, obtained using the MINOS near detector exposed to a wide-band beam with peak flux at 3 GeV, are compared to a conventional treatment of neutrino scattering within a Fermi gas nucleus. Results are used to guide the selection of a subsample enriched in quasielastic nu Fe-mu interactions, containing an estimated 123,000 quasielastic events of incident energies 1 \u3c E-nu \u3c 8 GeV, with \u3c E-nu \u3e = 2.79 GeV. Four additional subsamples representing topological and kinematic sideband regions to quasielastic scattering are also selected for the purpose of evaluating backgrounds. Comparisons using subsample distributions in four-momentum transfer Q(2) show the Monte Carlo model to be inadequate at low Q(2). Its shortcomings are remedied via inclusion of a Q(2)-dependent suppression function for baryon resonance production, developed from the data. A chi-square fit of the resulting Monte Carlo simulation to the shape of the Q(2) distribution for the quasielastic-enriched sample is carried out with the axial-vector mass M-A of the dipole axial-vector form factor of the neutron as a free parameter. The effective M-A which best describes the data is 1.23(-0.09)(+0.13)(fit)(-0.15)(+0.12)(syst) GeV

    Observation of seasonal variation of atmospheric multiple-muon events in the MINOS Near and Far Detectors

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    We report the first observation of seasonal modulations in the rates of cosmic ray multiple-muon events at two underground sites, the MINOS Near Detector with an overburden of 225 mwe, and the MINOS Far Detector site at 2100 mwe. At the deeper site, multiple-muon events with muons separated by more than 8 m exhibit a seasonal rate that peaks during the summer, similar to that of single-muon events. In contrast and unexpectedly, the rate of multiple-muon events with muons separated by less than 5-8 m, and the rate of multiple-muon events in the smaller, shallower Near Detector, exhibit a seasonal rate modulation that peaks in the winter

    Measurement of the multiple-muon charge ratio in the MINOS Far Detector

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    The charge ratio, R-mu = N mu + / N mu-, for cosmogenic multiple-muon events observed at an underground depth of 2070 mwe has been measured using the magnetized MINOS Far Detector. The multiple-muon events, recorded nearly continuously from August 2003 until April 2012, comprise two independent data sets imaged with opposite magnetic field polarities, the comparison of which allows the systematic uncertainties of the measurement to be minimized. The multiple-muon charge ratio is determined to be R mu = 1.104 + / - 0.006(stat)(-0.010)( + 0.009) (syst). This measurement complements previous determinations of single-muon and multiple-muon charge ratios at underground sites and serves to constrain models of cosmic-ray interactions at TeV energies

    Precision measurement of the speed of propagation of neutrinos using the MINOS detectors

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    We report a two-detector measurement of the propagation speed of neutrinos over a baseline of 734 km. The measurement was made with the NuMI beam at Fermilab between the near and far MINOS detectors. The fractional difference between the neutrino speed and the speed of light is determined to be (v/c - 1) = (1.0 +/- 1.1) x 10(-6), consistent with relativistic neutrinos

    Experimental studies of ECRH/ECCD effects on Tearing Mode stability using the new TCV real-time control system

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    Abstract GP9.00075 submitted for the DPP10 Meeting of The American Physical Society
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