662 research outputs found

    Interactions between Economic Growth and Environmental Quality in Shenzhen, China's First Special Economic Zone

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    The relationship between economic development and environmental quality is a debated topic. Environmental Kuznets Curve (EKC) is one prominent hypothesis, positing an inverted U-shaped development-environment relationship. Here we test this hypothesis using data from Shenzhen, Peoples Republic of China. Established in 1980 as the first special economic zone in China, Shenzhen has developed from a small village into a large urban-industrial agglomeration with the highest income level in the country. The enormous expansion of infrastructure, industrial sites and urban settlements has profoundly changed the local environment. We utilize environmental monitoring data from Shenzhen on concentration of pollutants in ambient air, main rivers, and near shore waters from 1989 to 2003. The results show that production-induced pollutants support EKC while consumption-induced pollutants do not support it

    Effects of electrojet turbulence on a magnetosphere-ionosphere simulation of a geomagnetic storm

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    Ionospheric conductance plays an important role in regulating the response of the magnetosphere‐ionosphere system to solar wind driving. Typically, models of magnetosphere‐ionosphere coupling include changes to ionospheric conductance driven by extreme ultraviolet ionization and electron precipitation. This paper shows that effects driven by the Farley‐Buneman instability can also create significant enhancements in the ionospheric conductance, with substantial impacts on geospace. We have implemented a method of including electrojet turbulence (ET) effects into the ionospheric conductance model utilized within geospace simulations. Our particular implementation is tested with simulations of the Lyon‐Fedder‐Mobarry global magnetosphere model coupled with the Rice Convection Model of the inner magnetosphere. We examine the impact of including ET‐modified conductances in a case study of the geomagnetic storm of 17 March 2013. Simulations with ET show a 13% reduction in the cross polar cap potential at the beginning of the storm and up to 20% increases in the Pedersen and Hall conductance. These simulation results show better agreement with Defense Meteorological Satellite Program observations, including capturing features of subauroral polarization streams. The field‐aligned current (FAC) patterns show little differences during the peak of storm and agree well with Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) reconstructions. Typically, the simulated FAC densities are stronger and at slightly higher latitudes than shown by AMPERE. The inner magnetospheric pressures derived from Tsyganenko‐Sitnov empirical magnetic field model show that the inclusion of the ET effects increases the peak pressure and brings the results into better agreement with the empirical model.This material is based upon work supported by NASA grants NNX14AI13G, NNX13AF92G, and NNX16AB80G. The National Center for Atmospheric Research is sponsored by the National Science Foundation. This work used the XSEDE and TACC computational facilities, supported by National Science Foundation grant ACI-1053575. We would like to acknowledge high-performance computing support from Yellowstone (ark:/85065/d7wd3xhc) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation. We thank the AMPERE team and the AMPERE Science Center for providing the Iridium derived data products. All model output, simulation codes, and analysis routines are being preserved on the NCAR High-Performance Storage System and will be made available upon written request to the lead author of this publication. (NNX14AI13G - NASA; NNX13AF92G - NASA; NNX16AB80G - NASA; National Science Foundation; ACI-1053575 - National Science Foundation

    Chiral effect in plane isotropic micropolar elasticity and its application to chiral lattices

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    In continuum mechanics, the non-centrosymmetric micropolar theory is usually used to capture the chirality inherent in materials. However when reduced to a two dimensional (2D) isotropic problem, the resulting model becomes non-chiral. Therefore, influence of the chiral effect cannot be properly characterized by existing theories for 2D chiral solids. To circumvent this difficulty, based on reinterpretation of isotropic tensors in a 2D case, we propose a continuum theory to model the chiral effect for 2D isotropic chiral solids. A single material parameter related to chirality is introduced to characterize the coupling between the bulk deformation and the internal rotation which is a fundamental feature of 2D chiral solids. Coherently, the proposed continuum theory is also derived for a triangular chiral lattice from a homogenization procedure, from which the effective material constants of the lattice are analytically determined. The unique behavior in the chiral lattice is demonstrated through the analyses of a static tension problem and a plane wave propagation problem. The results, which cannot be predicted by the non-chiral model, are validated by the exact solution of the discrete model.Comment: 33 pages, 7 figure

    Bayesian solutions to the label switching problem

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    The label switching problem, the unidentifiability of the permutation of clusters or more generally latent variables, makes interpretation of results computed with MCMC sampling difficult. We introduce a fully Bayesian treatment of the permutations which performs better than alternatives. The method can be used to compute summaries of the posterior samples even for nonparametric Bayesian methods, for which no good solutions exist so far. Although being approximative in this case, the results are very promising. The summaries are intuitively appealing: A summarized cluster is defined as a set of points for which the likelihood of being in the same cluster is maximized

    Leading Order Textures for Lepton Mass Matrices

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    In theories with three light neutrinos, certain simplicity assumptions allow the construction of a complete list of leading order lepton mass matrices. These matrices are consistent with m_{tau} \neq 0, Delta m^2_{12} \ll Delta m^2_{23}, theta_{23} approx 1, and theta_{13} = 0, as suggested by measurements of atmospheric and solar neutrino fluxes. The list contains twelve generic cases: two have three degenerate neutrinos, eight have two neutrinos forming a Dirac state, and in only two cases is one neutrino much heavier than the other two. For each of these twelve generic cases the possible forms for the perturbations which yield m_{mu} are given. Ten special textures are also found.Comment: 17 pages, added reference

    Penetration depth anisotropy in two-band superconductors

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    The anisotropy of the London penetration depth is evaluated for two-band superconductors with arbitrary inter- and intra-band scattering times. If one of the bands is clean and the other is dirty in the absence of inter-band scattering, the anisotropy is dominated by the Fermi surface of the clean band and is weakly temperature dependent. The inter-band scattering also suppress the temperature dependence of the anisotropy

    Scalar Decay in Chaotic Mixing

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    I review the local theory of mixing, which focuses on infinitesimal blobs of scalar being advected and stretched by a random velocity field. An advantage of this theory is that it provides elegant analytical results. A disadvantage is that it is highly idealised. Nevertheless, it provides insight into the mechanism of chaotic mixing and the effect of random fluctuations on the rate of decay of the concentration field of a passive scalar.Comment: 35 pages, 15 figures. Springer-Verlag conference style svmult.cls (included). Published in "Transport in Geophysical Flows: Ten Years After," Proceedings of the Grand Combin Summer School, 14-24 June 2004, Valle d'Aosta, Italy. Fixed some typo
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