2,446 research outputs found

    Planetary geometry handbook: Venus positional data, 1988 - 2020, volume 2

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    Graphical data necessary for the analysis of planetary exploration missions to Venus are presented. Positional and geometric information spanning the time period from 1988 through 2020 is provided. The data and the usage are explained

    Planetary geometry handbook: Mars positional data, 1990 - 2020, volume 3

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    Graphical data necessary for the analysis of planetary exploration missions to Mars are presented. Positional and geometric information spanning the time period from 1990 through 2020 is provided. The data and usage are explained

    Planetary geometry handbook: Saturn positional data, 1985 - 2020, volume 5

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    Graphical data necessary for the analysis of planetary exploration missions to Saturn are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained

    Planetary geometry handbook: Jupiter positional data, 1985 - 2020, volume 4

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    Graphical data necessary for the analysis of planetary exploration missions to Jupiter are presented. Positional and geometric information spanning the time period from 1985 through 2020 is provided. The data and their usage are explained

    Decidability of Univariate Real Algebra with Predicates for Rational and Integer Powers

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    We prove decidability of univariate real algebra extended with predicates for rational and integer powers, i.e., (xnQ)(x^n \in \mathbb{Q}) and (xnZ)(x^n \in \mathbb{Z}). Our decision procedure combines computation over real algebraic cells with the rational root theorem and witness construction via algebraic number density arguments.Comment: To appear in CADE-25: 25th International Conference on Automated Deduction, 2015. Proceedings to be published by Springer-Verla

    Rubidium and lead abundances in giant stars of the globular clusters M 13 and NGC 6752

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    We present measurements of the neutron-capture elements Rb and Pb in five giant stars of the globular cluster NGC 6752 and Pb measurements in four giants of the globular cluster M 13. The abundances were derived by comparing synthetic spectra with high resolution, high signal-to-noise ratio spectra obtained using HDS on the Subaru telescope and MIKE on the Magellan telescope. The program stars span the range of the O-Al abundance variation. In NGC 6752, the mean abundances are [Rb/Fe] = -0.17 +/- 0.06 (sigma = 0.14), [Rb/Zr] = -0.12 +/- 0.06 (sigma = 0.13), and [Pb/Fe] = -0.17 +/- 0.04 (sigma = 0.08). In M 13 the mean abundance is [Pb/Fe] = -0.28 +/- 0.03 (sigma = 0.06). Within the measurement uncertainties, we find no evidence for a star-to-star variation for either Rb or Pb within these clusters. None of the abundance ratios [Rb/Fe], [Rb/Zr], or [Pb/Fe] are correlated with the Al abundance. NGC 6752 may have slightly lower abundances of [Rb/Fe] and [Rb/Zr] compared to the small sample of field stars at the same metallicity. For M 13 and NGC 6752 the Pb abundances are in accord with predictions from a Galactic chemical evolution model. If metal-poor intermediate-mass asymptotic giant branch stars did produce the globular cluster abundance anomalies, then such stars do not synthesize significant quantities of Rb or Pb. Alternatively, if such stars do synthesize large amounts of Rb or Pb, then they are not responsible for the abundance anomalies seen in globular clusters.Comment: Accepted for publication in Ap

    LONG-TERM TILLAGE EFFECTS ON CONTINUOUS CORN YIELDS

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    Long-term comparisons of alternative tillage systems are needed to evaluate their effect on corn (Zea mays L.) yield under the variable temperature and rainfall conditions of the Corn Belt. Our objective was to evaluate long-term effects of alternative tillage systems on corn growth and yield on low organic matter silt loam soils. The effect of no-tillage (NT), chisel plow (CP), and moldboard plow (MP) treatments on plant density and grain yield was measured from 1981 through 1990 on Palsgrove and Rozetta silt loam (fine-silty, mixed mesic Typic Hapludalfs) soils. Tillage treatments were randomly allocated to plots in 1981 and treatments were applied in subsequent years without rerandomization. Therefore, measurements over years on the same plot were treated as repeated measures. Grain yields for all tillage treatments were primarily affected by water stress, which varied with yearly weather conditions. Grain yield decreased approximately 0.3 Mg ha-1 per cm weighted water stress (WWS) for WWS \u3e8 cm. No statistically significant yield differences among tillage treatments, when averaged over the 10-year period covered by the experiment, were detected. A combined analysis indicated that yield differences among tillage treatments did not depend on whether water stress or non-stress conditions occurred. Over half the variation in yearly differences in grain yield between tilled and NT treatments was explained by differences in plant density. Years were classified as stress or non-stress years on the basis of observed water stress and yearly weather factors. Variability among years was partitioned into variability among years within stress years and non-stress years. The difference in mean yields between ending (1989-90) and beginning (1981-82) years were used to investigate cumUlative effects of tillage treatments

    Rubidium and Lead Abundances in Giant Stars of the Globular Clusters M4 and M5

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    We present measurements of the neutron-capture elements Rb and Pb for bright giants in the globular clusters M4 and M5. The clusters are of similar metallicity ([Fe/H] ≃ -1.2), but M4 is decidedly s-process enriched relative to M5: [Ba/Fe] = +0.6 for M

    Relating two standard notions of secrecy

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    Two styles of definitions are usually considered to express that a security protocol preserves the confidentiality of a data s. Reachability-based secrecy means that s should never be disclosed while equivalence-based secrecy states that two executions of a protocol with distinct instances for s should be indistinguishable to an attacker. Although the second formulation ensures a higher level of security and is closer to cryptographic notions of secrecy, decidability results and automatic tools have mainly focused on the first definition so far. This paper initiates a systematic investigation of the situations where syntactic secrecy entails strong secrecy. We show that in the passive case, reachability-based secrecy actually implies equivalence-based secrecy for digital signatures, symmetric and asymmetric encryption provided that the primitives are probabilistic. For active adversaries, we provide sufficient (and rather tight) conditions on the protocol for this implication to hold.Comment: 29 pages, published in LMC

    Rubidium and lead abundances in giant stars of the globular clusters M4 and M5

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    We present measurements of the neutron-capture elements Rb and Pb for bright giants in the globular clusters M4 and M5. The clusters are of similar metallicity ([Fe/H] = -1.2) but M4 is decidedly s-process enriched relative to M5: [Ba/Fe] = +0.6 for M4 but 0.0 for M5. The Rb and Pb abundances were derived by comparing synthetic spectra with high-resolution, high signal-to-noise ratio spectra obtained with MIKE on the Magellan telescope. Abundances of Y, Zr, La, and Eu were also obtained. In M4, the mean abundances from 12 giants are [Rb/Fe] = 0.39 +/- 0.02 (sigma = 0.07), [Rb/Zr] = 0.17 +/- 0.03 (sigma = 0.08), and [Pb/Fe] = 0.30 +/- 0.02 (sigma = 0.07). In M5, the mean abundances from two giants are [Rb/Fe] = 0.00 +/- 0.05 (sigma = 0.06), [Rb/Zr] = 0.08 +/- 0.08 (sigma = 0.11), and [Pb/Fe] = -0.35 +/- 0.02 (sigma = 0.04). Within the measurement uncertainties, the abundance ratios [Rb/Fe], [Pb/Fe] and [Rb/X] for X = Y, Zr, La are constant from star-to-star in each cluster and none of these ratios are correlated with O or Na abundances. While M4 has a higher Rb abundance than M5, the ratios [Rb/X] are similar in both clusters indicating that the nature of the s-products are very similar for each cluster but the gas from which M4's stars formed had a higher concentration of these products.Comment: Accepted for publication in Ap
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