10,599 research outputs found

    Acoustic Emission Monitoring of the Syracuse Athena Temple: Scale Invariance in the Timing of Ruptures

    No full text
    We perform a comparative statistical analysis between the acoustic-emission time series from the ancient Greek Athena temple in Syracuse and the sequence of nearby earthquakes. We find an apparent association between acoustic-emission bursts and the earthquake occurrence. The waiting-time distributions for acoustic-emission and earthquake time series are described by a unique scaling law indicating self-similarity over a wide range of magnitude scales. This evidence suggests a correlation between the aging process of the temple and the local seismic activit

    "Universal" Distribution of Inter-Earthquake Times Explained

    Full text link
    We propose a simple theory for the ``universal'' scaling law previously reported for the distributions of waiting times between earthquakes. It is based on a largely used benchmark model of seismicity, which just assumes no difference in the physics of foreshocks, mainshocks and aftershocks. Our theoretical calculations provide good fits to the data and show that universality is only approximate. We conclude that the distributions of inter-event times do not reveal more information than what is already known from the Gutenberg-Richter and the Omori power laws. Our results reinforces the view that triggering of earthquakes by other earthquakes is a key physical mechanism to understand seismicity.Comment: 4 pages with two figure

    Phenomenological implications of an alternative Hamiltonian constraint for quantum cosmology

    Full text link
    In this paper we review a model based on loop quantum cosmology that arises from a symmetry reduction of the self dual Plebanski action. In this formulation the symmetry reduction leads to a very simple Hamiltonian constraint that can be quantized explicitly in the framework of loop quantum cosmology. We investigate the phenomenological implications of this model in the semi-classical regime and compare those with the known results of the standard Loop Quantum Cosmology.Comment: 10 pages, 7 figure

    Small-scale phase separation in doped anisotropic antiferromagnets

    Full text link
    We analyze the possibility of the nanoscale phase separation manifesting itself in the formation of ferromagnetic (FM) polarons (FM droplets) in the general situation of doped anisotropic three- and two-dimensional antiferromagnets. In these cases, we calculate the shape of the most energetically favorable droplets. We show that the binding energy and the volume of a FM droplet in the three-dimensional (3D) case depend only upon two universal parameters Jˉ=(Jx+Jy+Jz)S2\bar{J} =(J_x + J_y + J_z)S^2 and teff=(txtytz)1/3t_{eff} =(t_xt_yt_z)^{1/3}, where Jˉ\bar{J} and tefft_{eff} are effective antiferromagnetic (AFM) exchange and hopping integrals, respectively. In the two-dimensional (2D) case, these parameters have the form Jˉ=(Jx+Jy)S2\bar{J} =(J_x + J_y)S^2 and teff=(txty)1/2t_{eff} =(t_xt_y)^{1/2}. The most favorable shape of a ferromagnetic droplet corresponds to an ellipse in the 2D case and to an ellipsoid in the 3D case.Comment: 6 pages, 1 figure, RevTe

    Adsorption and two-body recombination of atomic hydrogen on 3^3He-4^4He mixture films

    Full text link
    We present the first systematic measurement of the binding energy EaE_a of hydrogen atoms to the surface of saturated 3^3He-4^4He mixture films. EaE_a is found to decrease almost linearly from 1.14(1) K down to 0.39(1) K, when the population of the ground surface state of 3^3He grows from zero to 6×10146\times10^{14} cm2^{-2}, yielding the value 1.2(1)×10151.2(1)\times 10^{-15} K cm2^2 for the mean-field parameter of H-3^3He interaction in 2D. The experiments were carried out with overall 3^3He concentrations ranging from 0.1 ppm to 5 % as well as with commercial and isotopically purified 4^4He at temperatures 70...400 mK. Measuring by ESR the rate constants KaaK_{aa} and KabK_{ab} for second-order recombination of hydrogen atoms in hyperfine states aa and bb we find the ratio Kab/KaaK_{ab}/K_{aa} to be independent of the 3^3He content and to grow with temperature.Comment: 4 pages, 4 figures, all zipped in a sigle file. Submitted to Phys. Rev. Let

    Long-Term Clustering, Scaling, and Universality in the Temporal Occurrence of Earthquakes

    Full text link
    Scaling analysis reveals striking regularities in earthquake occurrence. The time between any one earthquake and that following it is random, but it is described by the same universal-probability distribution for any spatial region and magnitude range considered. When time is expressed in rescaled units, set by the averaged seismic activity, the self-similar nature of the process becomes apparent. The form of the probability distribution reveals that earthquakes tend to cluster in time, beyond the duration of aftershock sequences. Furthermore, if aftershock sequences are analysed in an analogous way, yet taking into account the fact that seismic activity is not constant but decays in time, the same universal distribution is found for the rescaled time between events.Comment: short paper, only 2 figure

    Interplay between Heavy Fermions and Crystal Field Excitation in Kondo Lattices. Low-Temperature Thermodynamics and Inelastic Neutron Scattering Spectra of CeNiSn

    Full text link
    The microscopic theory of interaction between the heavy fermions and the crystal field excitations in Kondo lattices is presented. It is shown that the heavy-fermion spectrum scaled by the Kondo temperature TKT_K can be modified by the crystal field excitations with the energy ΔCF\Delta_{CF} provided the inequality ΔCF<TK\Delta_{CF}<T_K is realized. On the base of general description of excitation spectrum the detailed qualitative and quantitative explanation of anisotropic inelastic neutron scattering spectra and low-temperature specific heat of orthorhombic CeNiSn is given. The theory resolves the apparent contradiction between the metallic conductivity and the gap-wise behavior of thermodynamic properties and spin response of CeNiSn at low temperatures.Comment: 24 pages (LaTeX), 12 Postscript figures, submitted to Phys.Rev.

    MASET: Multi-Attribute Software Evaluation Tool

    Get PDF
    Software developers and organizational users face many problems in identifying and evaluating features of software products. The products are complex, with numerous options, making design and development of applications time consuming and costly. With many users, it can be difficult to summarize user needs and priorities, let alone identify the functions and features that they need in the applications. Once functions and features are identified, a three stage least squares technique is used to identify and prioritize important features of software products. TheMulti-Attribute Software Evaluation Tool (MASET) can be used to evaluate existing software (commercial or in-house) or proposed features of new software products. This tool combines a series of functions into a software product that aids in the development of an evaluation questionaire, accepts input from respondents, prepares the input for the statistacal analysis package and uses an artifical intelligence module to analyze the result

    Fermion Masses without Higgs: A Supersymmetric Technicolor Model

    Get PDF
    We propose a supersymmetric technicolor model in which the electroweak symmetry breaking is communicated to the quarks and leptons by technicolored SU(2)WSU(2)_W-singlet scalars. When the technifermions condense, the quarks and leptons of the third generation acquire mass. The fermions of the other generations do not couple to the technicolored scalars but they receive masses from radiative corrections involving superpartners. As a result, the mass hierarchy between the fermion generations arises naturally. The model predicts the CP asymmetries in BB meson decays and in ΔS=1\Delta S = 1 transitions to be smaller by two orders of magnitude than the ones predicted in the Standard Model.Comment: 27 pages, latex, 4 figures (require feynman.tex). Changes in the notation. An Appendix presenting the soft supersymmetric breaking terms is added. Few more details included in the discussion of the flavor-changing neutral current
    corecore