894 research outputs found
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Failed ISCHEMIA Trial or Failed Ischemia Testing?
The results of the ISCHEMIA (International Study of Comparative Health Effectiveness With Medical and Invasive Approach) trial were presented at the American Heart Association Scientific Sessions in November, 2019 in Philadelphia, Pennsylvania, and recently published on March 30, 2020 in the New England Journal of Medicine. After an average follow-up of 3.5 years, invasive therapy did not reduce the major adverse cardiac event (MACE) rate compared with optimal medical therapy (OMT) in patients with stable ischemic heart disease. However, the ISCHEMIA trial results might stem from the revascularization of inappropriate vessels and from the lack of a lesion-specific ischemia detection algorithm to guide revascularization instead of conventional stress testing. The utilization of an initial computed tomography (CT) angiogram with or without fractional flow reserve CT could have produced better revascularization results
Pairing symmetry signatures of T1 in superconducting ferromagnets
We study the nuclear relaxation rate 1/T1 as a function of temperature for a
superconducting-ferromagnetic coexistent system using a p-wave triplet model
for the superconducting pairing symmetry. This calculation is contrasted with a
singlet s-wave one done previously, and we see for the s-wave case that there
is a Hebel-Slichter peak, albeit reduced due to the magnetization, and no peak
for the p-wave case. We then compare these results to a nuclear relaxation rate
experiment on UGe2 to determine the possible pairing symmetry signatures in
that material. It is seen that the experimental data is inconclusive to rule
out the possibility of s-wave pairing in .Comment: 4 pages, 4 figure
Incommensurate spin resonance in URu2Si2
We focus on inelastic neutron scattering in and argue that
observed gap in the fermion spectrum naturally leads to the spin feature
observed at energies at momenta at \bQ^* = (1\pm 0.4,
0,0). We discuss how spin features seen in can indeed be thought
of in terms of {\em spin resonance} that develops in HO state and is {\em not
related} to superconducting transition at 1.5K. In our analysis we assume that
the HO gap is due to a particle-hole condensate that connects nested parts of
the Fermi surface with nesting vector . Within this approach we can
predicted the behavior of the spin susceptibility at \bQ^* and find it to be
is strikingly similar to the phenomenology of resonance peaks in high-T and
heavy fermion superconductors. The energy of the resonance peak scales with
. We discuss observable consequences
spin resonance will have on neutron scattering and local density of states.Comment: 8 pgaes latex, 4 fig
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An inwardly rectifying K+ channel is required for patterning.
Mutations that disrupt function of the human inwardly rectifying potassium channel KIR2.1 are associated with the craniofacial and digital defects of Andersen-Tawil Syndrome, but the contribution of Kir channels to development is undefined. Deletion of mouse Kir2.1 also causes cleft palate and digital defects. These defects are strikingly similar to phenotypes that result from disrupted TGFβ/BMP signaling. We use Drosophila melanogaster to show that a Kir2.1 homolog, Irk2, affects development by disrupting BMP signaling. Phenotypes of irk2 deficient lines, a mutant irk2 allele, irk2 siRNA and expression of a dominant-negative Irk2 subunit (Irk2DN) all demonstrate that Irk2 function is necessary for development of the adult wing. Compromised Irk2 function causes wing-patterning defects similar to those found when signaling through a Drosophila BMP homolog, Decapentaplegic (Dpp), is disrupted. To determine whether Irk2 plays a role in the Dpp pathway, we generated flies in which both Irk2 and Dpp functions are reduced. Irk2DN phenotypes are enhanced by decreased Dpp signaling. In wild-type flies, Dpp signaling can be detected in stripes along the anterior/posterior boundary of the larval imaginal wing disc. Reducing function of Irk2 with siRNA, an irk2 deletion, or expression of Irk2DN reduces the Dpp signal in the wing disc. As Irk channels contribute to Dpp signaling in flies, a similar role for Kir2.1 in BMP signaling may explain the morphological defects of Andersen-Tawil Syndrome and the Kir2.1 knockout mouse
Quantum Magnetic Properties in Perovskite with Anderson Localized Artificial Spin-1/2
Quantum magnetic properties in a geometrically frustrated lattice of spin-1/2
magnet, such as quantum spin liquid or solid and the associated spin
fractionalization, are considered key in developing a new phase of matter. The
feasibility of observing the quantum magnetic properties, usually found in
geometrically frustrated lattice of spin-1/2 magnet, in a perovskite material
with controlled disorder is demonstrated. It is found that the controlled
chemical disorder, due to the chemical substitution of Ru ions by Co-ions, in a
simple perovskite CaRuO3 creates a random prototype configuration of artificial
spin-1/2 that forms dimer pairs between the nearest and further away ions. The
localization of the Co impurity in the Ru matrix is analyzed using the Anderson
localization formulation. The dimers of artificial spin-1/2, due to the
localization of Co impurities, exhibit singlet-to-triplet excitation at low
temperature without any ordered spin correlation. The localized gapped
excitation evolves into a gapless quasi-continuum as dimer pairs break and
create freely fluctuating fractionalized spins at high temperature. Together,
these properties hint at a new quantum magnetic state with strong resemblance
to the resonance valence bond system.Comment: 8 pages, 6 figure
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