4,568 research outputs found

    Asymptotic constancy for pseudo monotone dynamical systems on function spaces

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    AbstractA pseudo monotone dynamical system is a dynamical system which preserves the order relation between initial points and equilibrium points. The purpose of this paper is to present some convergence, oscillation, and order stability criteria for pseudo monotone dynamical systems on function spaces for which each constant function is an equilibrium point. Some applications to neutral functional differential equations and semilinear parabolic partial differential equations with Neumann boundary condition are given

    Looking for “interesting people”

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    Mobile dating applications play a prominent role in Chinese gay men’s social lives. Based on in-depth interviews with 21 participants, this study explores how urban gay singles in China develop social relationships on dating apps. It reveals that relationship development is often driven by casual conversations, which are not motivated by clear pragmatic purposes. Casual conversations tend to unfold around common hobbies or experiences, serving as a source of sociability, or satisfaction in socializing itself. In contrast to casual conversations, two forms of conversations are deemed highly instrumental and undesirable: one is the sex-oriented conversation aimed at immediate sexual encounters; the other is the interrogative conversation in which people ask private questions in a nonreciprocal and rigid way. Besides craving sociability, users “relationalize” casual sex by perceiving it as a form of social connection and endowing it with the potential to foster a relationship. This is also reflected in users’ preference for sexual partners with whom they can hold a conversation. Users also exploit the affordances of different media platforms and capture the relationship potential by platform switching. They switch to the mainstream media platform WeChat for mor

    Site investigation for the effects of vegetation on ground stability

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    The procedure for geotechnical site investigation is well established but little attention is currently given to investigating the potential of vegetation to assist with ground stability. This paper describes how routine investigation procedures may be adapted to consider the effects of the vegetation. It is recommended that the major part of the vegetation investigation is carried out, at relatively low cost, during the preliminary (desk) study phase of the investigation when there is maximum flexibility to take account of findings in the proposed design and construction. The techniques available for investigation of the effects of vegetation are reviewed and references provided for further consideration. As for general geotechnical investigation work, it is important that a balance of effort is maintained in the vegetation investigation between (a) site characterisation (defining and identifying the existing and proposed vegetation to suit the site and ground conditions), (b) testing (in-situ and laboratory testing of the vegetation and root systems to provide design parameters) and (c) modelling (to analyse the vegetation effects)

    Critical dynamics of the Potts model: short-time Monte Carlo simulations

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    We calculate the new dinamic exponent Ξ\theta of the 4-state Potts model, using short-time simulations. Our estimates Ξ1=−0.0471(33)\theta_{1}=-0.0471(33) and Ξ2=% \theta_{2}= −0.0429(11)-0.0429(11) obtained by following the behavior of the magnetization or measuring the evolution of the time correlation function of the magnetization corroborate the conjecture by Okano et. al. In addition, these values agree with previous estimate of the same dynamic exponent for the two-dimensional Ising model with three-spin interactions in one direction, that is known to belong to the same universality class as the 4-state Potts model. The anomalous dimension of initial magnetization % x_{0}=z\theta +\beta /\nu is calculated by an alternative way that mixes two different initial conditions. We have also estimated the values of the static exponents ÎČ\beta and Îœ\nu . They are in complete agreement with the pertinent results of the literature.Comment: 12 pages, 7 figure

    Effects of the Sustainable Forestry Initiative on Landscape Pattern and Processes

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    We used simulation modeling to study the changes in landscape pattern and function resulting from the application of the Sustainable Forestry Initiative (SFI) program in East Texas, USA. Changes in landscape structure were examined by comparing landscapes with different management histories. The effects of pattern on processes were analyzed considering vertebrate habitat quality and configuration and hydrological processes such as water and sediment yield. Landscapes managed according to the SFI program presented increased general fragmentation. The application of measures under SFI increased habitat diversity in the landscape as well as Habitat Suitability Index (HSI) values for most of the species. Habitat for species requiring large patches of mature forest was almost absent. Landscapes managed under the SFI program showed lower sediment yield at the watershed level than those under the non-SFI program due to higher channel erosion related to the absence of buffer strips in the non-SFI scenario

    Ni-Cr textured substrates with reduced ferromagnetism for coated conductor applications

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    A series of biaxially textured Ni(1-x)Cr(x) materials, with compositions x = 0, 7, 9, 11, and 13 at % Cr, have been studied for use as substrate materials in coated conductor applications with high temperature superconductors. The magnetic properties were investigated, including the hysteretic loss in a Ni-7 at % Cr sample that was controllably deformed; for comparison, the loss was also measured in a similarly deformed pure Ni substrate. Complementary X-ray diffraction studies show that thermo-mechanical processing produces nearly complete {100} cube texturing, as desired for applications.Comment: PDF only; 19 pp., incl 10 figure

    The role of the sustainable forestry Initiative in forest landscape changes in Texas, USA

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    We studied the changes in landscape pattern and function resulting from the application of the Sustainable Forestry Initiative (SFI) in East Texas, USA. Changes in landscape structure were studied by comparing land-scapes with different management histories. A methodology to integrate landscape and stand pattern dynamics with processes was developed based upon modeling and simulation. The effects of pattern on processes were analyzed with this methodology considering the quality, quantity and con-figuration of vertebrate habitat and hydrological processes. Comparisons among landscapes revealed that forest management has a strong influence on landscape structure. The SFI program has increased overall fragmentation with an increase in number of patches, length of edges and shape complexity and a decrease in patch size, and number and size of core areas. Management according to the SFI program resulted generally in higher habitat suitability for many of the species analyzed and higher habitat di-versity in the landscape. The SFI program induced fragmentation of the habitat of pine warbler and the establishment of narrow and elongated habitats in a network structure for most of the remaining species. Land-scapes managed under the SFI program showed lower sediment yield at the watershed level than those under the non-SFI program due to lower channel erosion. The effects of the SFI program at the landscape level are related to the network of buffer strips. In general we conclude that relevant measures at the landscape level improve the sustainability of forested landscapes in East Texas

    Collapse of the vortex-lattice inductance and shear modulus at the melting transition in untwinned YBa2Cu3O7\rm YBa_2Cu_3O_7

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    The complex resistivity ρ^(ω)\hat{\rho}(\omega) of the vortex lattice in an untwinned crystal of 93-K YBa2Cu3O7\rm YBa_2Cu_3O_7 has been measured at frequencies ω/2π\omega/2\pi from 100 kHz to 20 MHz in a 2-Tesla field H∄c\bf H\parallel c, using a 4-probe RF transmission technique that enables continuous measurements versus ω\omega and temperature TT. As TT is increased, the inductance Ls(ω)=Imρ^(ω)/ω{\cal L}_s(\omega) ={\rm Im} \hat{\rho}(\omega)/ \omega increases steeply to a cusp at the melting temperature TmT_m, and then undergoes a steep collapse consistent with vanishing of the shear modulus c66c_{66}. We discuss in detail the separation of the vortex-lattice inductance from the `volume' inductance, and other skin-depth effects. To analyze the spectra, we consider a weakly disordered lattice with a low pin density. Close fits are obtained to ρ1(ω)\rho_1(\omega) over 2 decades in ω\omega. Values of the pinning parameter Îș\kappa and shear modulus c66c_{66} obtained show that c66c_{66} collapses by over 4 decades at TmT_m, whereas Îș\kappa remains finite.Comment: 11 pages, 8 figures, Phys. Rev. B, in pres

    Electron correlation in the Si(100) surface

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    Motivated by the controversy between quantum chemists and solid-state physicists, and by recent experimental results, spin-polarized density-functional (DFT) calculations are used to probe electron correlation in the Si(100) reconstructed surface. The ground state displays antiferromagnetic spin polarization for low dimer inclinations indicating, not magnetic order, but the importance of Mott-like correlations among dangling bonds. The lowest energy corresponds to a higher dimer inclination with no spin. DFT energies, however, should be taken with caution here. Our results together with quantum-chemical findings suggest dimers with highly correlated electrons that tend to buckle due to interactions with other dimers.Comment: 5 pages, 1 eps figure, 1 table; RevTeX v3.1. To appear in Surface Science (proceedings of the European Conference On Surface Science, ECOSS-19, Madrid, Sept. 5-8, 2000

    Modification of the pattern informatics method for forecasting large earthquake events using complex eigenvectors

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    Recent studies have shown that real-valued principal component analysis can be applied to earthquake fault systems for forecasting and prediction. In addition, theoretical analysis indicates that earthquake stresses may obey a wave-like equation, having solutions with inverse frequencies for a given fault similar to those that characterize the time intervals between the largest events on the fault. It is therefore desirable to apply complex principal component analysis to develop earthquake forecast algorithms. In this paper we modify the Pattern Informatics method of earthquake forecasting to take advantage of the wave-like properties of seismic stresses and utilize the Hilbert transform to create complex eigenvectors out of measured time series. We show that Pattern Informatics analyses using complex eigenvectors create short-term forecast hot-spot maps that differ from hot-spot maps created using only real-valued data and suggest methods of analyzing the differences and calculating the information gain.Comment: 13 pages, 1 figure. Submitted to Tectonophysics on 30 August 200
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