Direct Determination of Electron-Phonon Coupling Matrix Element in a Correlated System

High-resolution electron energy loss spectroscopy measurements have been carried out on an optimally doped cuprate Bi2Sr2CaCu2O8+{\delta}. The momentum-dependent linewidth and the dispersion of an A1 optical phonon are obtained. Based on these data as well as the detailed knowledge of the electronic structure from angle-resolved photoemission spectroscopy, we develop a scheme to determine the full structure of electron-phonon coupling for a specific phonon mode, thus providing a general method for directly resolving the EPC matrix element in systems with anisotropic electronic structures

Exposure to p,p′-DDE: A Risk Factor for Type 2 Diabetes

BACKGROUND: Persistent organic pollutants (POPs), such as PCBs, DDT and dioxins have in several cross-sectional studies shown strong associations with type 2 diabetes mellitus. Reversed causality can however not be excluded. The aim of this case-control study was to evaluate whether POPs concentration is a risk factor for type 2 diabetes. METHODOLOGY/PRINCIPAL FINDINGS: A case-control study was performed within a well-defined cohort of women, age 50-59 years, from the Southern part of Sweden. Biomarkers for POP exposure, 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE) were analyzed in stored serum samples, which were collected at the baseline examination when the cohort was established. For 107 out of the 371 cases, serum samples were stored at least three years before their type 2 diabetes was diagnosed. In this data set, CB-153 and p,p'-DDE were not associated with an increased risk to develop type 2 diabetes. However, when only the cases (n = 39) that were diagnosed more than six years after the baseline examination and their controls were studied, the women in the highest exposed quartile showed an increased risk to develop type 2 diabetes (OR of 1.6 [95% 0.61, 4.0] for CB-153 and 5.5 [95% CI 1.2, 25] for p,p'-DDE). CONCLUSIONS/SIGNIFICANCE: The results from the present case-control study, including a follow-up design, confirms that p,p'-DDE exposure can be a risk factor for type 2 diabetes

Ab initio method for band-structure calculations on structurally disordered materials : vibrational properties of 4"d" transition metals

An approximate method for electron band-structure calculations on structurally disordered materials is presented. Our approach is essentially a linear-muffin-tin-orbital calculation in which the structure matrix of a disordered supercell is reduced to the size of one atom per unit cell through an averaging procedure. Potential fluctuations are included by treating Madelung shifts as perturbations. A lattice of atoms with uncorrelated displacements is studied, and we show how total-energy results should be compared with experimental thermodynamic information. In particular, we expect an almost quasiharmonic behavior for calculated thermodynamic properties. We use our method to calculate Debye temperatures FTHETAD, for all 4d transition metals from Zr to Pd in the bcc, fcc, and hcp structures, and we discuss the physical reasons for variations in FTHETAD. Anharmonic effects are studied by determining thermal expansions and bulk moduli as functions of temperature. Being an ab initio calculation, our results are in very good agreement with experiment. Electronic energy spectra at finite temperatures are presented and we comment on similarities with previous results on liquid transition metals