1,025 research outputs found

    Bulk, rare earth and other trace elements in Apollo 14 and 15 and Luna 16 samples

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    The chemical abundances were measured by instrumental and radiochemical neutron activation analysis in a variety of lunar specimens. Apollo 14 soils are characterized by significant enrichments of Al2O3, Na2O and K2O and depletions of TiO2, FeO, MnO and Cr2O3 relative to Apollo 11 and to most of Apollo 12 soils. The uniform abundances in 14230 core tube soils and three other Apollo 14 soils indicate that the regolith is uniform to at least 22 cm depth and within approximately 200 m from the lunar module. Two Luna 16 breccias are similar in composition to Luna 16 soils. Four Apollo 15 soils (LM, STA 4, 9, and 9a) have variable compositions. Interelement correlations between MnO-FeO, Sc-FeO, V-Cr2O3 and K2O-Hf negate the hypothesis that howardite achondrites may be primitive lunar matter, argue against the fission hypothesis for the origin of the moon, and precludes any selective large scale volatilization of alkalies during lunar magmatic events

    Asymptotics of a discrete-time particle system near a reflecting boundary

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    We examine a discrete-time Markovian particle system on the quarter-plane introduced by M. Defosseux. The vertical boundary acts as a reflecting wall. The particle system lies in the Anisotropic Kardar-Parisi-Zhang with a wall universality class. After projecting to a single horizontal level, we take the longtime asymptotics and obtain the discrete Jacobi and symmetric Pearcey kernels. This is achieved by showing that the particle system is identical to a Markov chain arising from representations of the infinite-dimensional orthogonal group. The fixed-time marginals of this Markov chain are known to be determinantal point processes, allowing us to take the limit of the correlation kernel. We also give a simple example which shows that in the multi-level case, the particle system and the Markov chain evolve differently.Comment: 16 pages, Version 2 improves the expositio

    Metallic phase in stoichiometric CeOBiS 2 revealed by space-resolved ARPES

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    Recently CeOBiS2 system without any fluorine doping is found to show superconductivity posing question on its origin. Using space resolved ARPES we have found a metallic phase embedded in the morphological defects and at the sample edges of stoichiometric CeOBiS2. While bulk of the sample is semiconducting, the embedded metallic phase is characterized by the usual electron pocket at X point, similar to the Fermi surface of doped BiS2-based superconductors. Typical size of the observed metallic domain is larger than the superconducting correlation length of the system suggesting that the observed superconductivity in undoped CeOBiS2 might be due to this embedded metallic phase at the defects. The results also suggest a possible way to develop new systems by manipulation of the defects in these chalcogenides with structural instability

    Towards real-time community detection in large networks

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    The recent boom of large-scale Online Social Networks (OSNs) both enables and necessitates the use of parallelisable and scalable computational techniques for their analysis. We examine the problem of real-time community detection and a recently proposed linear time - O(m) on a network with m edges - label propagation or "epidemic" community detection algorithm. We identify characteristics and drawbacks of the algorithm and extend it by incorporating different heuristics to facilitate reliable and multifunctional real-time community detection. With limited computational resources, we employ the algorithm on OSN data with 1 million nodes and about 58 million directed edges. Experiments and benchmarks reveal that the extended algorithm is not only faster but its community detection accuracy is compared favourably over popular modularity-gain optimization algorithms known to suffer from their resolution limits.Comment: 10 pages, 11 figure

    Asymptotic function for multi-growth surfaces using power-law noise

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    Numerical simulations are used to investigate the multiaffine exponent αq\alpha_q and multi-growth exponent βq\beta_q of ballistic deposition growth for noise obeying a power-law distribution. The simulated values of βq\beta_q are compared with the asymptotic function βq=1q\beta_q = \frac{1}{q} that is approximated from the power-law behavior of the distribution of height differences over time. They are in good agreement for large qq. The simulated αq\alpha_q is found in the range 1q≤αq≤2q+1\frac{1}{q} \leq \alpha_q \leq \frac{2}{q+1}. This implies that large rare events tend to break the KPZ universality scaling-law at higher order qq.Comment: 5 pages, 4 figures, to be published in Phys. Rev.

    Classification of KPZQ and BDP models by multiaffine analysis

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    We argue differences between the Kardar-Parisi-Zhang with Quenched disorder (KPZQ) and the Ballistic Deposition with Power-law noise (BDP) models, using the multiaffine analysis method. The KPZQ and the BDP models show mono-affinity and multiaffinity, respectively. This difference results from the different distribution types of neighbor-height differences in growth paths. Exponential and power-law distributions are observed in the KPZQ and the BDP, respectively. In addition, we point out the difference of profiles directly, i.e., although the surface profiles of both models and the growth path of the BDP model are rough, the growth path of the KPZQ model is smooth.Comment: 11 pages, 6 figure

    Finite time corrections in KPZ growth models

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    We consider some models in the Kardar-Parisi-Zhang universality class, namely the polynuclear growth model and the totally/partially asymmetric simple exclusion process. For these models, in the limit of large time t, universality of fluctuations has been previously obtained. In this paper we consider the convergence to the limiting distributions and determine the (non-universal) first order corrections, which turn out to be a non-random shift of order t^{-1/3} (of order 1 in microscopic units). Subtracting this deterministic correction, the convergence is then of order t^{-2/3}. We also determine the strength of asymmetry in the exclusion process for which the shift is zero. Finally, we discuss to what extend the discreteness of the model has an effect on the fitting functions.Comment: 34 pages, 5 figures, LaTeX; Improved version including shift of PASEP height functio
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