Many-Impurity Effects in Fourier Transform Scanning Tunneling Spectroscopy

Fourier transform scanning tunneling spectroscopy (FTSTS) is a useful technique for extracting details of the momentum-resolved electronic band structure from inhomogeneities in the local density of states due to disorder-related quasiparticle scattering. To a large extent, current understanding of FTSTS is based on models of Friedel oscillations near isolated impurities. Here, a framework for understanding many-impurity effects is developed based on a systematic treatment of the variance Delta rho^2(q,omega) of the Fourier transformed local density of states rho(q,\omega). One important consequence of this work is a demonstration that the poor signal-to-noise ratio inherent in rho(q,omega) due to randomness in impurity positions can be eliminated by configuration averaging Delta rho^2(q,omega). Furthermore, we develop a diagrammatic perturbation theory for Delta rho^2(q,omega) and show that an important bulk quantity, the mean-free-path, can be extracted from FTSTS experiments.Comment: 7 pages, 5 figures. A version of the paper with high resolution, colour figures is available at http://www.trentu.ca/physics/batkinson/FTSTS.ps.gz minor revisions in response to refree report + figure 5 is modifie

The first computer model of currents in the Kurai Intermountane Basin, Altai, under release of a glacial-dammed lake

The first 2D computer model of the currents (including circulation currents) inside the glacial dammed Kurai Lake under its release caused by the dam break is simulated in the RMA2 program of the SMS 9.2 modeling system. The hydraulic parameters are calculated for several given water discharges in the transit flow (from 10 to 0.3 million m3/s) of the basin. A consecutive change in the circulation currents during the release of the lake is identified. A comparison of the character of circulation and the calculated fields of the depths and the current velocities in the lake with the orientation of the gravel ranges on the bottom of the Kurai basin allows reconstruction of the hydraulic conditions of possible formation of the giant ripple fields

Local edge modes in doped cuprates with checkerboard polaronic heterogeneity

We study a periodic polaronic system, which exhibits a nanoscale superlattice structure, as a model for hole-doped cuprates with checkerboard-like heterogeneity, as has been observed recently by scanning tunneling microscopy (STM). Within this model, the electronic and phononic excitations are investigated by applying an unrestricted Hartree-Fock and a random phase approximation (RPA) to a multiband Peierls-Hubbard Hamiltonian in two dimensions

Fluctuating Asymmetry of Measurable Parameters in Rana arvalis : Methodology

72 Fluctuating asymmetry (FA), i.e., undirected deviations from bilateral symmetry, of both measurable and nonmeasurable characteristics reflects ontogenetic instability, which some authors believe increases in response to genomic or environmental stress. This allows FA to be used for estimating the state of anthropogenically affected natural populations (e.g., Rana arvalis young of the year were captured on August 4 and 5, 2003, in the Kalinovskie Razrezy Park Forest in northern Yekaterinburg ( n = 26) and near the Yuzhnaya Bus Terminal ( n = 15), respectively. Ponds existing in the park forest had resulted from flooding desolate quarries. The vegetation was a herb-grass pine forest containing small shrubs. The results of our hydrochemical analyses performed in 2003 indicate that, according to the ecological sanitary classification of the quality of surface waters suggested by We measured the size parameters of the body that are standard for amphibians The results of the measurements shown in the table indicate that storage in the fixative led to a slight decrease in the mean values of most parameters measured in frogs from both populations. This decrease was the largest (and statistically significant) for the lengths of the thigh, crus, and temporal spot, i.e., the measurements at least partly involving soft tissue (F = 11.13-144.32, d.f. = 1/25 or 1/14, P = 0.004-0.0001 for the results of ANOVA with factors individual, body side