61 research outputs found
Only Fermi-Liquids are Metals
Any singular deviation from Landau Fermi-liquid theory appears to lead, for
arbitrarily small concentration of impurities coupling to a non-conserved
quantity, to a vanishing density of states at the chemical potential and
infinite resistivity as temperature approaches zero. Applications to
copper-oxide metals including the temperature dependence of the anisotropy in
resistivity, and to other cases of non Fermi-liquids are discussed.Comment: 11 pages,revtex, 1 Postscript figur
Whither Correlated Electron Theory?
This is the text of the 'Theory' opening talk at the 2001 Strongly Correlated
Electron Systems conference. It contains opinions about some of the outstanding
scientific challenges facing the theory side of the correlated electrons field.Comment: 7 pages. No figures. To appear in Physica
Non Fermi Liquid Behaviour near a spin-glass transition
In this paper we study the competition between the Kondo effect and RKKY
interactions near the zero-temperature quantum critical point of an Ising-like
metallic spin-glass. We consider the mean-field behaviour of various physical
quantities. In the `quantum- critical regime' non-analytic corrections to the
Fermi liquid behaviour are found for the specific heat and uniform static
susceptibility, while the resistivity and NMR relaxation rate have a non-Fermi
liquid dependence on temperature.Comment: 15 pages, RevTex 3.0, 1 uuencoded ps. figure at the en
A New Unconventional Antiferromagnet, YbPt
We report the synthesis and basic properties of single crystals of a new
binary compound, YbPt. The Yb ions in this compound are fully
trivalent, and heat capacity measurements show that the crystal field scheme
involves a doublet ground state, well separated from the excited states, which
are fully occupied above 150 K. The heat capacity displays a large,
weakly first order anomaly at 2.4 K, where a cusp is observed in the magnetic
susceptibility signalling the onset of antiferromagnetic order. The entropy
associated with this order is the full Rln2 of the doublet ground state,
however the magnetic susceptibility in the ordered phase is dominated by a
large and temperature independent component below the Neel temperature. The
heat capacity in the ordered state originates with ferromagnetic spin waves,
giving evidence for the inherently local moment character of the ordered state.
The electrical resistivity is unusually large, and becomes quadratic in
temperature exactly at the Neel temperature. The absence of analogous Fermi
liquid behavior in the heat capacity and the magnetic susceptibility implies
that YbPt is a low electron density system, where the Fermi surface
is further gapped by the onset of magnetic order.Comment: 8 pages, 9 figure
The NOX toolbox: validating the role of NADPH oxidases in physiology and disease
Reactive oxygen species (ROS) are cellular signals but also disease triggers; their relative excess (oxidative stress) or shortage (reductive stress) compared to reducing equivalents are potentially deleterious. This may explain why antioxidants fail to combat diseases that correlate with oxidative stress. Instead, targeting of disease-relevant enzymatic ROS sources that leaves physiological ROS signaling unaffected may be more beneficial. NADPH oxidases are the only known enzyme family with the sole function to produce ROS. Of the catalytic NADPH oxidase subunits (NOX), NOX4 is the most widely distributed isoform. We provide here a critical review of the currently available experimental tools to assess the role of NOX and especially NOX4, i.e. knock-out mice, siRNAs, antibodies, and pharmacological inhibitors. We then focus on the characterization of the small molecule NADPH oxidase inhibitor, VAS2870, in vitro and in vivo, its specificity, selectivity, and possible mechanism of action. Finally, we discuss the validation of NOX4 as a potential therapeutic target for indications including stroke, heart failure, and fibrosis
NADPH oxidases: key modulators in aging and age-related cardiovascular diseases?
Reactive oxygen species (ROS) and oxidative stress have long been linked to aging and diseases prominent in the elderly such as hypertension, atherosclerosis, diabetes and atrial fibrillation (AF). NADPH oxidases (Nox) are a major source of ROS in the vasculature and are key players in mediating redox signalling under physiological and pathophysiological conditions. In this review, we focus on the Nox-mediated ROS signalling pathways involved in the regulation of 'longevity genes' and recapitulate their role in age-associated vascular changes and in the development of age-related cardiovascular diseases (CVDs). This review is predicated on burgeoning knowledge that Nox-derived ROS propagate tightly regulated yet varied signalling pathways, which, at the cellular level, may lead to diminished repair, the aging process and predisposition to CVDs. In addition, we briefly describe emerging Nox therapies and their potential in improving the health of the elderly population
Ypk1, the yeast orthologue of the human serum- and glucocorticoid-induced kinase, is required for efficient uptake of fatty acids
ChemInform Abstract: Non-Fermi-Liquid Behavior and Magnetic Fluctuations at the Quantum Phase Transition in CeCu6-xAux.
EFFECT OF ELECTRON-ELECTRON INTERACTION NEAR THE METAL-INSULATOR TRANSITION IN DOPED SEMICONDUCTORS STUDIED WITHIN THE LOCAL DENSITY APPROXIMATION
Suppression of the structural phase transition in CeCu<sub>6</sub> by pressure and Au doping
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