2,464 research outputs found
Deformation pattern around the Conejera fault blocks (Asturian Basin, North Iberian Margin)
The Asturian Basin is located on the coastline of the North Iberian Margin. This basin is dissected by long-lived E-, NE- and NW-striking faults that delineate a series of extensional fault blocks that became shortened during the Upper Cretaceous to Cenozoic Alpine convergence. In the Conejera cove, the NE-striking and SE-dipping Conejera Fault displays a remarkable example of contractional deformation, promoted by the mechanical contrast within the Lower to Middle Jurassic stratigraphic series. Field observations and structural analysis carried out in this study reveal: i) a first system of orthogonal cross-joints oblique to the Conejera Fault and other major onshore boundary faults, ii) a second system of meso-extensional faults parallel to the Conejera Fault, and developed by the reactivation and linkage of the orthogonal cross-joints and iii) a series of contractional folds, thrusts and pressure solution with a predominant NE to ENE trend. Observed relationships and structural analysis suggest an obliquity between the here inferred direction of the Late Jurassic-Early Cretaceous stretching (i.e. about N015E) and the onshore boundary faults, whereas the contractional structures are broadly parallel to the NE-striking Conejera Fault and suggest a roughly SSE- to SE-oriented Alpine convergence
Searching for signatures of chaos in gamma-ray light curves of selected Fermi-LAT blazars
Blazar variability appears to be stochastic in nature. However, a possibility
of low-dimensional chaos was considered in the past, but with no unambiguous
detection so far. If present, it would constrain the emission mechanism by
suggesting an underlying dynamical system. We rigorously searched for
signatures of chaos in Fermi-Large Area Telescope light curves of 11 blazars.
The data were comprehensively investigated using the methods of nonlinear time
series analysis: phase-space reconstruction, fractal dimension, maximal
Lyapunov exponent (mLE). We tested several possible parameters affecting the
outcomes, in particular the mLE, in order to verify the spuriousness of the
outcomes. We found no signs of chaos in any of the analyzed blazars. Blazar
variability is either truly stochastic in nature, or governed by
high-dimensional chaos that can often resemble randomness.Comment: Pages : 7, figures: 5, accepted in MNRA
First-order structural transition and pressure-induced lattice/phonon anomalies in Sr2IrO4
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOTwo intriguing unresolved issues of iridate physics are the avoided metallization under applied pressure of undoped Sr2IrO4 and related materials, and the apparent absence of superconductivity under electron doping despite the similarity of the fermiology of these materials with respect to cuprates. Here, we investigate the crystal structure and lattice vibrations of Sr2IrO4 by a combined phonon Raman scattering and x-ray powder diffraction experiment under pressures up to 66 GPa and room temperature. Density functional theory (DFT) and ab initio lattice dynamics calculations were also carried out. A first-order structural phase transition associated with an 8% collapse of the c-axis is observed at high pressures, with phase coexistence being observed between similar to 40 and 55 GPa. At lower pressures and still within the high-symmetry tetragonal phase, a number of lattice and phonon anomalies were observed, reflecting crossovers between isostructural competing states. A critical pressure of P-1 = 17 GPa is associated with the following anomalies: (i) a reduction of lattice volume compressibility and a change of behavior of the tetragonal c/a ratio take place above P-1 ||(ii) a fourfold symmetry-breaking lattice strain associated with lattice disorder is observed above P-1 ||(iii) two strong Raman-active modes at ambient conditions (at similar to 180 and similar to 260 cm -1 ) are washed out at P-1 ||and (iv) an asymmetric Fano line shape is observed for the similar to 390 cm(-1) mode above P i , revealing a coupling of this phonon with electronic excitations. DFT indicates that the Ir-4(+) in-plane canted magnetic moment is unstable against volumetric compression, indicating that the phase above P-1 is most likely nonmagnetic. Exploring the similarities between iridate and cuprate physics, we argue that these observations are consistent with the emergence of a rotational symmetry-breaking electronic instability at P-1 , providing hints for the avoided metallization under pressure and supporting the hypothesis of possible competing orders that are detrimental to superconductivity in this family. Alternative scenarios for the transition at P-1 are also suggested and critically discussed. Additional phonon and lattice anomalies in the tetragonal phase are observed at P-2 = 30 and P-3 = 40 GPa, indicating that other competing phases are favored at high pressures.989118FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2012/04870-72016/00756-6sem informaçãosem informaçã
Prevalence of pre-diabetes and undiagnosed diabetes in the Mollerussa prospective observational cohort study in a semi-rural area of Catalonia
Objectives: To assess the prevalence of undiagnosed diabetes and pre-diabetes in the healthy population in the Mollerussa cohort. As a secondary objective, to identify the variables associated with these conditions and to describe the changes in glycaemic status after 1 year of follow-up in subjects with pre-diabetes. Design: Prospective observational cohort study. Setting: General population from a semi-rural area. Participants: The study included 583 participants without a diagnosis of diabetes recruited between March 2011 and July 2014. Results: The prevalence of undiagnosed diabetes was 20, 3.4% (95% CI 2.6 to 4.2) and that of pre-diabetes was 229, 39.3% (37.3 to 41.3). Among those with pre-diabetes, 18.3% had isolated impaired fasting plasma glucose (FPG) (FPG: 100 to <126 mg/dL), 58.1% had isolated impaired glycated haemoglobin (HbA1c) (HbA1c 5.7 to <6.5) and 23.6% fulfilled both criteria. Follow-up data were available for 166 subjects; 41.6%(37.8 to 45.4) returned to normoglycaemia, 57.6% (57.8 to 61.4) persisted in pre-diabetes and 0.6% (0 to 1.2) progressed to diabetes. Individuals with pre-diabetes had worse cardiometabolic risk profiles and sociodemographic features than normoglycaemic subjects. In the logistic regression model, variables significantly associated with pre-diabetes were older age (OR; 95% CI) (1.033; 1.011 to 1.056), higher physical activity (0.546; 0.360 to 0.827), body mass index (1.121; 1.029 to 1.222) and a family history of diabetes (1.543; 1.025 to 2.323). The variables significantly associated with glycaemic normalisation were older age (0.948; 0.916 to 0.982) and body mass index (0.779; 0.651 to 0.931). Conclusions: Among adults in our region, the estimated prevalence of undiagnosed diabetes was 3.4% and that of pre-diabetes was 39.3%. After a 1-year follow-up, a small proportion of subjects (0.6%) with pre-diabetes progressed to diabetes, while a high proportion (41.6%) returned to normoglycaemia. Individuals with pre-diabetes who returned to normoglycaemia were younger and had a lower body mass inde
Anisotropic lattice compression and pressure-induced electronic phase transitions in Sr2IrO4
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQThe crystal lattice of Sr2IrO4 is investigated with synchrotron x-ray powder diffraction under hydrostatic pressures up to P = 43 GPa and temperatures down to 20 K. The tetragonal unit cell is maintained over the whole investigated pressure range, within101716FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ2016/00756-62017/10581-12018/20142-8308607/2018-0409504/2018-1We thank D. Haskel and G. Fabbris for illuminating discussions and for sharing unpublished data, and M. Eleotério, J. Fonseca Júnior, and R. D. Reis for technical assistance. LNLS is acknowledged for concession of beamtime. This work was supported by Fap
Inhomogeneous magnetism in La-doped CaMnO3. (I) Nanometric-scale spin clusters and long-range spin canting
Neutron measurements on Ca{1-x}La{x}MnO3 (0.00 <= x <= 0.20) reveal the
development of a liquid-like spatial distribution of magnetic droplets of
average size ~10 Angstroms, the concentration of which is proportional to x
(one cluster per ~60 doped electrons). In addition, a long-range ordered
ferromagnetic component is observed for ~0.05 < x < ~0.14. This component is
perpendicularly coupled to the simple G-type antiferromagnetic (G-AFM)
structure of the undoped compound, which is a signature of a G-AFM + FM
spin-canted state. The possible relationship between cluster formation and the
stabilization of a long-range spin-canting for intermediate doping is
discussed.Comment: Submitted to Physical Review
The JNK inhibitor, SP600125, potentiates the glial response and cell death induced by methamphetamine in the mouse striatum
This study investigates the effect of the selective Jun NH2-terminal kinase 1/2 (JNK1/2) inhibitor, (SP600125) on the striatal dopamine nerve terminal loss and on the increased interleukin-15 (IL-15) expression and glial response induced by methamphetamine (METH). Mice were given repeated low doses of METH (4Â mg/kg, i.p., three times separated by 3Â h) and killed 24Â h or 7 d after the last dose. SP600125 (30Â mg/kg, i.p) was administered 30Â min before the last METH injection. Results indicate that METH produced dopaminergic axonal neurotoxicity reflected as a marked decrease in the striatal density of tyrosine hydroxylase-immunoreactive (TH-ir) fibres and dopamine transporter-immunoreactivity (DAT-ir) 24Â h after dosing. These effects were not modified by SP600125. This compound also failed to prevent the long-term loss of dopamine levels and DAT observed 7 d following METH injection. Nevertheless, SP600125 potentiated METH-induced striatal cell loss reflected by an increase in Fluoro-Jade immunostaining, cleaved capase-3 immunoreactivity and the number of terminal deoxyncleotidyl transferase-mediated dUTP nick end labelling (TUNEL) positive cells. In line with a deleterious effect of JNK1/2 inhibition, SP600125 increased the astroglial and microglial response induced by METH and interfered with drug-induced IL-15 expression. Together these data indicate that, not only does SP600125 fail to protect against the dopaminergic damage induced by METH but also, in fact, it potentiates the glial response and the non-dopaminergic striatal cell loss caused by the drug. © 2013 CINP.Peer Reviewe
Phonons and Magnetic Excitations in Mott-Insulator LaTiO
The polarized Raman spectra of stoichiometric LaTiO (T K) were
measured between 6 and 300 K. In contrast to earlier report on half-metallic
LaTiO, neither strong background scattering, nor Fano shape of the
Raman lines was observed. The high frequency phonon line at 655 cm
exhibits anomalous softening below T: a signature for structural
rearrangement. The assignment of the Raman lines was done by comparison to the
calculations of lattice dynamics and the nature of structural changes upon
magnetic ordering are discussed. The broad Raman band, which appears in the
antiferromagnetic phase, is assigned to two-magnon scattering. The estimated
superexchange constant meV is in excellent agreement with the
result of neutron scattering studies.Comment: 4 pages, 5 figure
Inhomogeneous Magnetism in La-doped CaMnO3. (II) Mesoscopic Phase Separation due to Lattice-coupled FM Interactions
A detailed investigation of mesoscopic magnetic and crystallographic phase
separation in Ca(1-x)La(x)MnO3, 0.00<=x<=0.20, is reported. Neutron powder
diffraction and DC-magnetization techniques have been used to isolate the
different roles played by electrons doped into the eg level as a function of
their concentration x. The presence of multiple low-temperature magnetic and
crystallographic phases within individual polycrystalline samples is argued to
be an intrinsic feature of the system that follows from the shifting balance
between competing FM and AFM interactions as a function of temperature. FM
double-exchange interactions associated with doped eg electrons are favored
over competing AFM interactions at higher temperatures, and couple more
strongly with the lattice via orbital polarization. These FM interactions
thereby play a privileged role, even at low eg electron concentrations, by
virtue of structural modifications induced above the AFM transition
temperatures.Comment: 8 pages, 7 figure
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