5,705 research outputs found
Role of surface states in STM spectroscopy of (111) metal surfaces with Kondo adsorbates
A nearly-free-electron (NFE) model to describe STM spectroscopy of (111)
metal surfaces with Kondo impurities is presented. Surface states are found to
play an important role giving a larger contribution to the conductance in the
case of Cu(111) and Au(111) than Ag(111) surfaces. This difference arises from
the farther extension of the Ag(111) surface state into the substrate. The
different line shapes observed when Co is adsorbed on different substrates can
be explained from the position of the surface band onset relative to the Fermi
energy. The lateral dependence of the line shape amplitude is found to be
bulk-like for R|| < 4 Amstrongs and surface-like at larger distances, in
agreement with experimental data.Comment: 4 pages, 3 eps figure
Fluctuation diagnostics of the electron self-energy: Origin of the pseudogap physics
We demonstrate how to identify which physical processes dominate the
low-energy spectral functions of correlated electron systems. We obtain an
unambiguous classification through an analysis of the equation of motion for
the electron self-energy in its charge, spin and particle-particle
representations. Our procedure is then employed to clarify the controversial
physics responsible for the appearance of the pseudogap in correlated systems.
We illustrate our method by examining the attractive and repulsive Hubbard
model in two-dimensions. In the latter, spin fluctuations are identified as the
origin of the pseudogap, and we also explain why wave pairing fluctuations
play a marginal role in suppressing the low-energy spectral weight, independent
of their actual strength.Comment: 6 pages, 2 figures + 4 pages supplementar
Phonon anomalies due to strong electronic correlations in layered organic metals
We show how the coupling between the phonons and electrons in a strongly
correlated metal can result in phonon frequencies which have a non-monotonic
temperature dependence. Dynamical mean-field theory is used to study the
Hubbard-Holstein model that describes the \kappa-(BEDT-TTF)_2 X family of
superconducting molecular crystals. The crossover with increasing temperature
from a Fermi liquid to a bad metal produces phonon anomalies that are
consistent with recent Raman scattering and acoustic experiments.Comment: 6 pages, 3 eps figure
Long-Term Adherence to IFN Beta-1a Treatment when Using RebiSmart® Device in Patients with Relapsing-Remitting Multiple Sclerosis
The effectiveness of disease-modifying drugs in the treatment of multiple sclerosis is associated with adherence. RebiSmart (R) electronic device provides useful information about adherence to the treatment with subcutaneous (sc) interferon (IFN) beta-1 alpha (Rebif (R)). The aim of the study was to determine long-term adherence to this treatment in patients with relapsing-remitting multiple sclerosis (RRMS). This retrospective multicentre observational study analysed 258 patients with RRMS who were receiving sc IFN beta-1 alpha (Rebif (R)) treatment by using RebiSmart (R) until replacement (36 months maximum lifetime) or treatment discontinuation. Adherence was calculated with data (injection dosage, time, and date) automatically recorded by RebiSmart (R). Patients in the study had a mean age of 41 years with a female proportion of 68%. Mean EDSS score at start of treatment was 1.8 (95% CI, 1.6-1.9). Overall adherence was 92.6%(95% CI, 90.6-94.5%). A total of 30.2% of patients achieved an adherence rate of 100%, 80.6% at least 90%, and only 13.2% of patients showed a suboptimal adherence (<80%). A total of 59.9% of subjects were relapse-free after treatment initiation. Among 106 subjects (41.1%) who experienced, on average, 1.4 relapses, the majority were mild (40.6%) or moderate (47.2%). Having experienced relapses from the beginning of the treatment was the only variable significantly related to achieving an adherence of at least 80% (OR = 3.06, 1.28-7.31). Results of this study indicate that sc IFN beta-1 alpha administration facilitated by RebiSmart (R) could lead to high rates of adherence to a prescribed dose regimen over 36 months
- …