1,309 research outputs found
Elusive electron-phonon coupling in quantitative analyses of the spectral function
We examine multiple techniques for extracting information from angle-resolved
photoemission spectroscopy (ARPES) data, and test them against simulated
spectral functions for electron-phonon coupling. We find that, in the
low-coupling regime, it is possible to extract self-energy and bare-band
parameters through a self-consistent Kramers-Kronig bare-band fitting routine.
We also show that the effective coupling parameters deduced from the
renormalization of quasiparticle mass, velocity, and spectral weight are
momentum dependent and, in general, distinct from the true microscopic
coupling; the latter is thus not readily accessible in the quasiparticle
dispersion revealed by ARPES.Comment: A high-resolution version can be found at
http://www.physics.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Articles/KKBF.pd
How close is the bench to the bedside? Metabolic profiling in cancer research
Metabolic profiling using mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR) is integral to the rapidly expanding field of metabolomics, which is making progress in toxicology, plant science and various diseases, including cancer. In the area of oncology and metabolic phenotyping, researchers have probed the known changes in malignant cellular pathways using new experimental techniques to gain more insights, and others are exploiting these same cellular pathways for therapeutic drug targets and for novel cancer biomarkers, with the ultimate goal of translation to the clinic. Here, we discuss the challenges and opportunities in metabolic phenotyping for discovering novel cancer biomarkers, and we assess the clinical applicability of MS and NMR
Why some children accept under-informative utterances
Binary judgement on under-informative utterances (e.g. Some horses jumped over the fence, when all horses did) is the most widely used methodology to test children’s ability to generate implicatures. Accepting under-informative utterances is considered a failure to generate implicatures. We present off-line and reaction time evidence for the Pragmatic Tolerance Hypothesis, according to which some children who accept under-informative utterances are in fact competent with implicature but do not consider pragmatic violations grave enough to reject the critical utterance. Seventy-five Dutch-speaking four to nine-year-olds completed a binary (Experiment A) and a ternary judgement task (Experiment B). Half of the children who accepted an utterance in Experiment A penalised it in Experiment B. Reaction times revealed that these children experienced a slow-down in the critical utterances in Experiment A, suggesting that they detected the pragmatic violation even though they did not reject it. We propose that binary judgement tasks systematically underestimate children’s competence with pragmatics
Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap
We study Na2IrO3 by ARPES, optics, and band structure calculations in the
local-density approximation (LDA). The weak dispersion of the Ir 5d-t2g
manifold highlights the importance of structural distortions and spin-orbit
coupling (SO) in driving the system closer to a Mott transition. We detect an
insulating gap {\Delta}_gap = 340 meV which, at variance with a Slater-type
description, is already open at 300 K and does not show significant temperature
dependence even across T_N ~ 15 K. An LDA analysis with the inclusion of SO and
Coulomb repulsion U reveals that, while the prodromes of an underlying
insulating state are already found in LDA+SO, the correct gap magnitude can
only be reproduced by LDA+SO+U, with U = 3 eV. This establishes Na2IrO3 as a
novel type of Mott-like correlated insulator in which Coulomb and relativistic
effects have to be treated on an equal footing.Comment: Accepted in Physical Review Letters. Auxiliary and related material
can be found at:
http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.htm
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