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Search Results: 1 - 10 of 191585 matches for " Phillips G "
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An Incomplete Diagnosis
Phillips Jr., Alan G.
Ars Disputandi : the Online Journal for Philosophy of Religion , 2007,
Abstract: In this discussion note, I examine scattered comments about evil from John Dewey's works. After a brief consideration of what critics like Reinhold Niebuhr have said about the weaknesses of Dewey's theodicy, I will offer my own critique. In short, I argue that Dewey subverts his own theory of inquiry when he comes to the problem of the origin and genesis of evil.
Observations of the Germination Behavior of Tilletia indica Teliospores on the Soil Surface under Varying Simulated Environmental Conditions  [PDF]
Gary L. Peterson, Dana K. Berner, John G. Phillips
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.811196
Abstract: A series of replicated growth chamber studies were conducted to determine the effects of soil type and simulated European temperature conditions from fall planting to anthesis in Hungary, United Kingdom, Italy and Norway on the initiation of Tilletia indica teliospore germination on the soil surface. A concurrent study examined effects on teliospore germination of a simulated temperature profile for Ciudad Obregon, Mexico, where Karnal bunt is known to occur. Three soil moisture treatments were tested; 40.5% water holding capacity (WHC), 16.2% WHC and weekly fluctuation of soil WHC. Results suggest that soil type would not have a significant effect on germination during the cropping season. Under all conditions tested, some portion of the teliospore population remained dormant but viable throughout the entire season. In comparing Mexican and Hungarian temperature profiles, highest soil surface germination for the Hungarian profile was at 40.5% WHC during the first 30 days of the simulation (30 days after planting date). The highest germination for the Mexican profile was at the 16.2% WHC during the last 30 days of the study (time of anthesis).
40Ar/39Ar laser probe analyses of K-bearing titanates from kimberlites
G. B. Kiviets,D. Phillips
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02891473
Abstract:
Origin of the Mott Gap
R. G. Leigh,Philip Phillips
Physics , 2008, DOI: 10.1103/PhysRevB.79.245120
Abstract: We show exactly that the only charged excitations that exist in the strong-coupling limit of the half-filled Hubbard model are gapped composite excitations generated by the dynamics of the charge $2e$ boson that appears upon explicit integration of the high-energy scale. At every momentum, such excitations have non-zero spectral weight at two distinct energy scales separated by the on-site repulsion $U$. The result is a gap in the spectrum for the composite excitations accompanied by a discontinuous vanishing of the density of states at the chemical potential when $U$ exceeds the bandwidth. Consequently, we resolve the long-standing problem of the cause of the charge gap in a half-filled band in the absence of symmetry breaking.
Field Ordering and Energy Density in Texture Cosmology
Nicholas G. Phillips,A. Kogut
Physics , 1995, DOI: 10.1103/PhysRevLett.75.1264
Abstract: We use numerical simulations of the time evolution of global textures to investigate the relationship between ordering dynamics and energy density in an expanding universe. Events in which individual textures become fully wound are rare. The energy density is dominated by the more numerous partially wound configurations, with median topological charge alpha ~ 0.44. This verifies the recent supposition (Borrill et al. 1994) that such partially wound configurations should dominate the cosmic microwave background.
Universality Conjecture for all Airy, Sine and Bessel Kernels in the Complex Plane
G. Akemann,M. J. Phillips
Physics , 2012,
Abstract: We address the question of how the celebrated universality of local correlations for the real eigenvalues of Hermitian random matrices of size NxN can be extended to complex eigenvalues in the case of random matrices without symmetry. Depending on the location in the spectrum, particular large-N limits (the so-called weakly non-Hermitian limits) lead to one-parameter deformations of the Airy, sine and Bessel kernels into the complex plane. This makes their universality highly suggestive for all symmetry classes. We compare all the known limiting real kernels and their deformations into the complex plane for all three Dyson indices beta=1,2,4, corresponding to real, complex and quaternion real matrix elements. This includes new results for Airy kernels in the complex plane for beta=1,4. For the Gaussian ensembles of elliptic Ginibre and non-Hermitian Wishart matrices we give all kernels for finite N, built from orthogonal and skew-orthogonal polynomials in the complex plane. Finally we comment on how much is known to date regarding the universality of these kernels in the complex plane, and discuss some open problems.
Atomic Carbon in Galaxies
Maryvonne Gerin,Thomas G. Phillips
Physics , 2000, DOI: 10.1086/309072
Abstract: We present new measurements of the ground state fine-structure line of atomic carbon at 492 GHz in a variety of nearby external galaxies, ranging from spiral to irregular, interacting and merging types. In comparison with CO(1-0), the CI(1-0) intensity stays fairly comparable in the different environments, with an average value of the ratio of the line integrated areas in Kkm/s of CI(1-0)/CO(1-0) = 0.2 +/- 0.2. However, some variations can be found within galaxies, or between galaxies. Relative to CO lines, CI(1-0) is weaker in galactic nuclei, but stronger in disks, particularly outside star forming regions. Also, in NGC 891, the CI(1-0) emission follows the dust continuum at 1.3mm extremely well along the full length of the major axis where molecular gas is more abundant than atomic gas. Atomic carbon therefore appears to be a good tracer of molecular gas in external galaxies, possibly more reliable than CO. Atomic carbon can contribute significantly to the thermal budget of interstellar gas. Cooling due to C and CO amounts typically to 2 x 10^{-5} of the FIR continuum or 5% of the CII line. However, C and CO cooling reaches 30% of the gas total, in Ultra Luminous InfraRed Galaxies, where CII is abnormally faint. Together with CII/FIR, the emissivity ratio CI(1-0)/FIR can be used as a measure of the non-ionizing UV radiation field in galaxies.
Future Mm/Submm Instrumentation and Science Opportunities: Example of Deuterated Molecules
T. G. Phillips,C. Vastel
Physics , 2002,
Abstract: During the next decade a tremendous advance will take place in instrumentation for spectroscopy of the interstellar medium. Major new facilities (ALMA, SOFIA, APEX, LMT, Herschel and others) will be constructed and commissioned, so that the science opportunities, in the field of astrochemistry, will increase by a huge factor. This will be enhanced by the new receivers with greater bandwidth and sensitivity. The new opportunities will be in the area of astrochemistry of distant objects, through greater sensitivity, or new spectral ranges due to the platforms above the Earth's atmosphere. Various aspects of new spectral ranges are discussed, with emphasis on H2O lines, features previously hidden under H2O or O2 lines, light hydrides and particularly on deuterium in molecules. Recently, multiply deuterated species have been detected, e.g. ND3, in cold dense regions of the interstellar medium. It is argued here that it is possible that so much deuterium could be trapped, by the fractionation process, into heavy molecules such as ND3, etc..., and species such as H2D+ and possibly D2H+, that D and HD might be depleted. This would be the mechanism for the large dispersion of [D]/[H] values found in the interstellar medium. Light molecules (hydrides and deuterides) generally have large fundamental rotation frequencies, often lying in the HIFI bands. The deuterides are a specially suitable case, because the species exist mainly in cold dense regions, where the molecules are in the ground states and THz observations will best be carried out by absorption spectroscopy against background dust continuum sources such as Sgr B2 and W49N.
Neural Networks as a tool for parameter estimation in mega-pixel data sets
Nicholas G. Phillips,A. Kogut
Physics , 2001,
Abstract: We present a neural net algorithm for parameter estimation in the context of large cosmological data sets. Cosmological data sets present a particular challenge to pattern-recognition algorithms since the input patterns (galaxy redshift surveys, maps of cosmic microwave background anisotropy) are not fixed templates overlaid with random noise, but rather are random realizations whose information content lies in the correlations between data points. We train a ``committee'' of neural nets to distinguish between Monte Carlo simulations at fixed parameter values. Sampling the trained networks using additional Monte Carlo simulations generated at intermediate parameter values allows accurate interpolation to parameter values for which the networks were never trained. The Monte Carlo samples automatically provide the probability distributions and truth tables required for either a frequentist or Bayseian analysis of the one observable sky. We demonstrate that neural networks provide unbiased parameter estimation with comparable precision as maximum-likelihood algorithms but significant computational savings. In the context of CMB anisotropies, the computational cost for parameter estimation via neural networks scales as $N^{3/2}$. The results are insensitive to the noise levels and sampling schemes typical of large cosmological data sets and provide a desirable tool for the new generation of large, complex data sets.
Neural networks as a tool for parameter estimation in astrophysical data
Nicholas G. Phillips,A. Kogut
Physics , 2001,
Abstract: We present a neural net algorithm for parameter estimation in the context of large cosmological data sets. Cosmological data sets present a particular challenge to pattern-recognition algorithms since the input patterns (galaxy redshift surveys, maps of cosmic microwave background anisotropy) are not fixed templates overlaid with random noise, but rather are random realizations whose information content lies in the correlations between data points. We train a ``committee'' of neural nets to distinguish between Monte Carlo simulations at fixed parameter values. Sampling the trained networks using additional Monte Carlo simulations generated at intermediate parameter values allows accurate interpolation to parameter values for which the networks were never trained. The Monte Carlo samples automatically provide the probability distributions and truth tables required for either a frequentist or Bayseian analysis of the one observable sky. We demonstrate that neural networks provide unbiased parameter estimation with comparable precision as maximum-likelihood algorithms but significant computational savings. In the context of CMB anisotropies, the computational cost for parameter estimation via neural networks scales as $N^{3/2}$. The results are insensitive to the noise levels and sampling schemes typical of large cosmological data sets and provide a desirable tool for the new generation of large, complex data sets.
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