Numerical verification of universality for the Anderson transition

We analyze the scaling behavior of the higher Lyapunov exponents at the Anderson transition. We estimate the critical exponent and verify its universality and that of the critical conductance distribution for box, Gaussian and Lorentzian distributions of the random potential

Scaling of the conductance distribution near the Anderson transition

The single parameter scaling hypothesis is the foundation of our understanding of the Anderson transition. However, the conductance of a disordered system is a fluctuating quantity which does not obey a one parameter scaling law. It is essential to investigate the scaling of the full conductance distribution to establish the scaling hypothesis. We present a clear cut numerical demonstration that the conductance distribution indeed obeys one parameter scaling near the Anderson transition

Universality of the critical conductance distribution in various dimensions

We study numerically the metal - insulator transition in the Anderson model on various lattices with dimension $2 < d \le 4$ (bifractals and Euclidian lattices). The critical exponent $\nu$ and the critical conductance distribution are calculated. We confirm that $\nu$ depends only on the {\it spectral} dimension. The other parameters - critical disorder, critical conductance distribution and conductance cummulants - depend also on lattice topology. Thus only qualitative comparison with theoretical formulae for dimension dependence of the cummulants is possible

Topology dependent quantities at the Anderson transition

The boundary condition dependence of the critical behavior for the three dimensional Anderson transition is investigated. A strong dependence of the scaling function and the critical conductance distribution on the boundary conditions is found, while the critical disorder and critical exponent are found to be independent of the boundary conditions

Anderson transition in the three dimensional symplectic universality class

We study the Anderson transition in the SU(2) model and the Ando model. We report a new precise estimate of the critical exponent for the symplectic universality class of the Anderson transition. We also report numerical estimation of the $\beta$ function.Comment: 4 pages, 5 figure

Failure of single-parameter scaling of wave functions in Anderson localization

We show how to use properties of the vectors which are iterated in the transfer-matrix approach to Anderson localization, in order to generate the statistical distribution of electronic wavefunction amplitudes at arbitary distances from the origin of $L^{d-1} \times \infty$ disordered systems. For $d=1$ our approach is shown to reproduce exact diagonalization results available in the literature. In $d=2$, where strips of width $L \leq 64$ sites were used, attempted fits of gaussian (log-normal) forms to the wavefunction amplitude distributions result in effective localization lengths growing with distance, contrary to the prediction from single-parameter scaling theory. We also show that the distributions possess a negative skewness $S$, which is invariant under the usual histogram-collapse rescaling, and whose absolute value increases with distance. We find $0.15 \lesssim -S \lesssim 0.30$ for the range of parameters used in our study, .Comment: RevTeX 4, 6 pages, 4 eps figures. Phys. Rev. B (final version, to be published

Accuracy of [(18)Fluorine]-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography-Computed Tomography Response Assessment Following (Chemo) radiotherapy for Locally Advanced Laryngeal/Hypopharyngeal Carcinoma

Introduction: The accuracy of response assessment positron emission tomography (PET)-computed tomography (CT) following radiotherapy with or without chemotherapy for laryngeal/hypopharyngeal squamous cell carcinoma is uncertain. Methods: In all, 35 patients with laryngeal or hypopharyngeal squamous cell carcinoma who were treated between 2009 and 2014 with (chemo)radiotherapy were identified. The accuracy of response assessment PET-CT was made by correlation with clinical follow-up and pathological findings. Results: Of the 35 patients, 20 (57%) had an overall complete metabolic response. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for response assessment [18Fluorine]-fluoro-2-deoxy-d-glucose (FDG) PET-CT for primary and nodal sites, respectively, were 100%, 73%, 46%, and 100% and 83%, 95%, 83%, and 95%. Conclusions: Response assessment FDG PET-CT following (chemo)radiotherapy for laryngeal and hypopharyngeal carcinomas has a high NPV for both primary site and lymph nodes and can be used to guide treatment decisions. The PPV of residual FDG uptake at the primary tumour site is limited and requires examination and biopsy confirmation

Recent Decisions

Comments on recent decisions by L. D. Wichmann, Lawrence James Bradley, John F. Beggan, John A. Slevin, Robert P. Mone, and F. James Kane

Wavelength dependent collective effects in the multiphoton ionization of atomic deuterium

This paper presents the results of an experimental investigation into collective effects in the transient plasma formed by multiphoton ionization of atomic deuterium with a pulsed laser. The laser wavelength is varied in a narrow range around 243 nm, so that the photoionization is resonant with the metastable 2S1/2 state. The ion yield, the ion time-of-flight spectra, and the yield of Lyman-a photons have been measured as a function of laser intensity ~from 1 to 340 MW/cm2! and laser detuning around the 1S1/2-2S1/2 two-photon resonance. During and shortly after the laser pulse, collective effects resulting from the mutual interaction of the photoelectrons and the ions affect the spatial and temporal distribution of the ions. Because of the near-degeneracy of the 2S1/2, 2P1/2 , and 2P3/2 states, the resonant multiphoton ionization is affected by the Stark mixing of these states in the collective field. As a result, the time-dependent yields of ions and of Lyman-a photons are modulated by the interplay of the multiphoton ionization of the atoms and the collective effects in the plasma. From the measurements it is deduced that collective effects are important above a critical charge density of 33108 ions/cm3. An asymmetry is observed in the line profile of the total ion yield as a function of laser detuning. This asymmetry is interpreted to be due to the effect of the collective field upon the intermediate resonant 2S1/2 state of the photoionization process