6,430 research outputs found
Iron Displacements and Magnetoelastic Coupling in the Spin-Ladder Compound BaFe2Se3
We report long-range ordered antiferromagnetism concomitant with local iron
displacements in the spin-ladder compound BaFeSe. Short-range magnetic
correlations, present at room temperature, develop into long-range
antiferromagnetic order below T = 256 K, with no superconductivity down to
1.8 K. Built of ferromagnetic Fe plaquettes, the magnetic ground state
correlates with local displacements of the Fe atoms. These iron displacements
imply significant magnetoelastic coupling in FeX-based materials, an
ingredient hypothesized to be important in the emergence of superconductivity.
This result also suggests that knowledge of these local displacements is
essential for properly understanding the electronic structure of these systems.
As with the copper oxide superconductors two decades ago, our results highlight
the importance of reduced dimensionality spin ladder compounds in the study of
the coupling of spin, charge, and atom positions in superconducting materials
Contrasting carbonate depositional systems for Pliocene cool-water limestones cropping out in central Hawke's Bay, New Zealand
Pliocene limestone formations in central Hawke's Bay (eastern North Island, New Zealand) accumulated on and near the margins of a narrow forearc basin seaway within the convergent Australia/Pacific plate boundary zone. The active tectonic setting and varied paleogeographic features of the limestone units investigated, in association with probable glacioeustatic sea-level fluctuations, resulted in complex stratigraphic architectures and contrasting types of carbonate accumulation on either side of the seaway. Here, we recognise recurring patterns of sedimentary facies, and sequences and systems tracts bounded by key physical surfaces within the limestone sheets. The facies types range from Bioclastic (B) to Siliciclastic (S) end-members via Mixed (M) carbonate-siliciclastic deposits. Skeletal components are typical cool-water associations dominated by epifaunal calcitic bivalves, bryozoans, and especially barnacles. Siliciclastic contents vary from one formation to another, and highlight siliciclastic-rich limestone units in the western ranges versus siliciclastic-poor limestone units in the eastern coastal hills. Heterogeneities in facies types, stratal patterns, and also in diagenetic pathways between eastern and western limestone units are considered to originate in the coeval occurrence in different parts of the forearc basin of two main morphodynamic carbonate systems over time
No indication of porcine reproductive and respiratory syndrome virus (PRRSV) infection in Brazilian swine herds.
Porcine reproductive and respiratory syndrome virus (PRRSV) is a globally important pathogen of economic and veterinary concern. Recent studies estimate a cost of US$664m yearly to United States swine industry 3. PRRS is present throughout the world, with the exception of Australia, New Zealand, Finland, Norway, Sweden and Switzerland 5. Although Brazilian swine production is expressive (fourth pork producer and exporter), there has been no evidence of PRRSV infection in those herds 1. Most of the analysis used serology by commercial ELISA tests in breeding herds to perform prevalence surveys. The objective of this work was to detect PRRSV in samples of sera, plasma or oral fluids (OF) from swine herds, quarantined imported boars and feral pigs from 2008 ? 2012
The Cauchy convergence of T and P-approximant templates for test-mass Kerr binary systems
In this work we examine the Cauchy convergence of both post-Newtonian
(T-approximant) and re-summed post-Newtonian (P-approximant) templates for the
case of a test-mass orbiting a Kerr black hole along a circular equatorial
orbit. The Cauchy criterion demands that the inner product between the and
order approximation approaches unity, as we increase the order of
approximation. In previous works, it has been shown that we achieve greater
fitting factors and better parameter estimation using the P-approximant
templates for both Schwarzschild and Kerr black holes. In this work, we show
that the P-approximant templates also display a faster Cauchy convergence
making them a superior template to the standard post-Newtonian templates.Comment: 5 pages, Replaced with shortened published versio
Detecção de anticorpos contra o vírus da influenza suína em rebanhos suínos.
Projeto/Plano de Ação: 03.09.04.600-01
Detecting gravitational waves from test-mass bodies orbiting a Kerr black hole with P-approximant templates
In this study we apply post-Newtonian (T-approximants) and resummed
post-Newtonian (P-approximants) to the case of a test-particle in equatorial
orbit around a Kerr black hole. We compare the two approximants by measuring
their effectualness (i.e. larger overlaps with the exact signal), and
faithfulness (i.e. smaller biases while measuring the parameters of the signal)
with the exact (numerical) waveforms. We find that in the case of prograde
orbits, T-approximant templates obtain an effectualness of ~0.99 for spins q <
0.75. For 0.75 < q < 0.95, the effectualness drops to about 0.82. The
P-approximants achieve effectualness of > 0.99 for all spins up to q = 0.95.
The bias in the estimation of parameters is much lower in the case of
P-approximants than T-approximants. We find that P-approximants are both
effectual and faithful and should be more effective than T-approximants as a
detection template family when q > 0. For q < 0 both T- and P-approximants
perform equally well so that either of them could be used as a detection
template family. However, for parameter estimation, the P-approximant templates
still outperforms the T-approximants.Comment: 11 Pages - 9 figures. Accepted for publication. Proceedings of GWDAW
9. Special edition of Classical and Quantum Gravit
Influence of the anion potential on the charge ordering in quasi-one dimensional charge transfer salts
We examine the various instabilities of quarter-filled strongly correlated
electronic chains in the presence of a coupling to the underlying lattice. To
mimic the physics of the (TMTTF)X Bechgaard-Fabre salts we also include
electrostatic effects of intercalated anions. We show that small displacements
of the anion can stabilize new mixed Charged Density Wave-Bond Order Wave
phases in which central symmetry centers are suppressed. This finding is
discussed in the context of recent experiments. We suggest that the recently
observed charge ordering is due to a cooperative effect between the Coulomb
interaction and the coupling of the electronic stacks to the anions. On the
other hand, the Spin-Peierls instability at lower temperature requires a
Peierls-like lattice coupling.Comment: Latex, 4 pages, 4 postscript figure
Density Matrix Approach to Local Hilbert Space Reduction
We present a density matrix approach for treating systems with a large or
infinite number of degrees of freedom per site with exact diagonalization or
the density matrix renormalization group. The method is demonstrated on the 1D
Holstein model of electrons coupled to Einstein phonons. In this system, two or
three optimized phonon modes per site give results as accurate as with 10-100
bare phonon levels per site.Comment: 4 pages, 4 figure
The triangular nasal notch sign in patients with Crohn's disease treated with tumor necrosis factor inhibitors
Tumor necrosis factor (TNF) inhibitors are used to treat a range of chronic inflammatory diseases, such as rheumatoid arthritis, inflammatory bowel disease and psoriasis. Some of the cutaneous side effects of these drugs are well documented, such as infections, skin carcinomas, palmoplantar and skinfold pustulosis, psoriasis-like or eczema-like lesions. We are not aware of TNF inhibitor-induced nasal lesions in the literature. We report a case series demonstrating a specific pattern of cicatricial nasal fissure (triangular nasal notch) following nasal dermatitis episodes in patients treated with TNF inhibitors. This article is protected by copyright. All rights reserved
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