545 research outputs found
Alluvial gravel sedimentation in a contractional growth fold setting, Sant Llorenc de Morunys, southeastern Pyrenees
This paper is included in the Special Publication entitled 'Cenozoic foreland basins of Western Europe' edited by A. Mascle, C. Puigdefabregas, H.P. Luterbacher and M. Fernandez. New data are presented on the classic growth structure at Sant Llorenc de Morunys (NE Ebro Basin, Spain). During the late Eocene to Oligocene thick alluvial-fan gravel sediments accumulated principally by repetitive sub-aerial mass flow (cohesionless debris flow and fluidal sediment flow) events, with smaller volumes of fan-stream flows. Subaerial, high-viscosity (cohesive) debris flows contributed comparatively small volumes of sediment to the succession. These sediments constructed a complex architecture of conglomeratic and sandstone-bearing lithosomes that were affected by stratal thickening and erosion across a growth fold pair and genetically related internal unconformities, which formed a long-lived thrust-related structure in the immediate footwall of the SE Pyrenean mountain front. Four periods of evolution for the Sant Llorenc growth structure are defined on the basis of distintive stratigraphical architecture. These describe a gross evolution from onlapping to overlapping growth strata, related to the ultimate demise of growth folding. In detail complex erosional and offlapping events punctuated the growth history, which shows extreme variation parallel to the axis of the structure. Patterns of palaeoflow were highly complex, showing distinct axial and transverse directions relatable to growth fold evolutionary periods. Palaeocurrents are considered to have been deflected and diverted by surficial differential subsidence and areas of relative uplift and erosion generated by fold growth. The complexity of sediment dispersal is compounded by variables intrinsic to alluvial fan environments. The Sant Llorenc de Morunys growth strata provide information on how sediments are reorganized by syndepositionally-growing structures and on the nature of sediment distribution between external fold-and-thrust belts and foreland basins
Methodology and reliability of respiratory muscle assessment
The optimal method for respiratory muscle endurance (RME) assessment remains unclear. This study assessed the test-retest reliability of two RME-test methodologies. Fifteen healthy adults attended the laboratory on four occasions, separated by 5 ± 2 days, and completed each test in a random, “one on two” order. They performed spirometry testing, maximal respiratory pressure assessment and two different RME tests: an inspiratory resistive breathing (IRB) and an isocapnic hyperpnea endurance (IHE) test. Typical error, expressed as coefficient of variation, for IRB maximal inspiratory pressure (MIP) and IHE maximal ventilation were 12.21 (8.85–19.67) % and 10.73 (7.78–17.29) %, respectively. Intraclass correlation coefficients for the same parameters were 0.83 (0.46-0.94) and 0.80 (0.41-0.93), respectively. No correlations were found between RME parameters derived from the IHE and IRB tests (all p > 0.05). Significant positive correlations were found between both IRB and IHE outcomes and spirometry parameters, MIP and maximal expiratory pressure (p < 0.05).Given these results, IRB and IHE appear to be suitable for RME testing in healthy people, although they may reflect different physiological mechanisms (respiratory mechanics and respiratory muscle capacity for IHE test vs. inspiratory muscle capacity for IRB test). Future studies are therefore warranted that compare IRB and IHE tests in clinical settings
Superconductivity of a Metallic Stripe Embedded in an Antiferromagnet
We study a simple model for the metallic stripes found in
: two chain Hubbard ladder embedded in a static
antiferromagnetic environments. We consider two cases: a ``topological
stripe'', for which the phase of the Neel order parameter shifts by
across the ladder, and a ``non-topological stripe'', for which there is no
phase shift across the ladder. We perform one-loop renormalization group
calculations to determine the low energy properties. We compare the results
with those of the isolated ladder and show that for small doping
superconductivity is enhanced in the topological stripe, and suppressed in the
non-topological one. In the topological stripe, the superconducting order
parameter is a mixture of a spin singlet component with zero momentum and a
spin triplet component with momentum . We argue that this mixture is
generic, and is due to the presence of a new term in the quantum
Ginzburg-Landau action. Some consequences of this mixing are discussed.Comment: 6 pages, 3 eps figure
Paleo-elevation and EET evolution at mountain ranges: inferences from flexural modeling in the Eastern Pyrenees and Ebro Basin
Implications of Charge Ordering for Single-Particle Properties of High-Tc Superconductors
The consequences of disordered charge stripes and antiphase spin domains for
the properties of the high-temperature superconductors are studied. We focus on
angle-resolved photoemission spectroscopy and optical conductivity, and show
that the many unusual features of the experimentally observed spectra can be
understood naturally in this way. This interpretation of the data, when
combined with evidence from neutron scattering and NMR, suggests that
disordered and fluctuating stripe phases are a common feature of
high-temperature superconductors.Comment: 4 pages, figures by fax or mai
Fault-controlled and stratabound dolostones in the Late Aptian-earliest Albian Benassal Formation (Maestrat Basin, E Spain) : petrology and geochemistry constrains
This study was developed under the ExxonMobil FC2 Alliance (Fundamental Controls on Flow in Carbonates). The authors wish to thank ExxonMobil Production Company and ExxonMobil Upstream Research Company for providing funding. The views in this article by Sherry L. Stafford are her own and not necessarily those of ExxonMobil. This research was supported by the Sedimentary Geology Research Group of the Generalitat de Catalunya (2014SGR251). We would like to thank Andrea Ceriani and Paola Ronchi for their critical and valuable reviews, and Associated Editor Piero Gianolla for the editorial work.Peer reviewedPostprin
Structural Disorder Induced Polaron Formation and Magnetic Scattering in the Disordered Holstein-Double Exchange Model
In this paper we present results on the disordered Holstein-Double Exchange
model, explicitly in three dimension and `metallic' densities, obtained by
using a recently developed Monte Carlo approach. Following up on our earlier
paper, cond-mat/0406085, here we provide a detailed microscopic picture of the
thermally driven metal-insulator transition (MIT) that arises close to the
ferromagnet to paramagnet transition in this problem. This paper is focused
mainly on the `diagnostics', clarifying the origin of the effective disorder
that drives the MIT in this system. To that effect, we provide results on the
thermal evolution of the distributions of (i) lattice distortions, (ii) the net
`structural disorder' and (iii) the `hopping disorder' arising from spin
randomness feeding back through the Hunds coupling. We suggest a phenomenology
for the thermally driven MIT, viewing it as an `Anderson-Holstein' transition.Comment: 6 pages, latex, JPSJ style, 7 eps figs. Style files included.
Proceedings of the SPQS Meeting at Sendai, Japan, 2004. To appear in JPS
Signatures of Stripe Phases in Hole Doped
We study nickelate-centered and oxygen-centered stripe phases in doped
LaNiO materials. We use an inhomogeneous Hartree-Fock and
random-phase approximation approach including both electron-electron and
electron-lattice(e-l) coupling for a layer of LaNiO. We find that
whether the ground state after commensurate hole doping comprises Ni-centered
or O-centered charge-localized stripes depends sensitively on the e-l
interaction. With increasing e-l interaction strength, a continuous transition
from an O-centered stripe phase to a Ni-centered one is found. Various low- and
high-energy signatures of these two kinds of stripe phases are predicted, which
can clearly distinguish them. These signatures reflect the strongly correlated
spin-charge-lattice features in the vicinity of Ni-centered or O-centered
stripe domains. The importance of e-l interaction for recent experiments on
stripe phases is discussed.Comment: 11 pages, 12 figures, to appear in Phys.Rev.B(July 1,1998
Optimal trapping wavelengths of Cs molecules in an optical lattice
The present paper aims at finding optimal parameters for trapping of Cs
molecules in optical lattices, with the perspective of creating a quantum
degenerate gas of ground-state molecules. We have calculated dynamic
polarizabilities of Cs molecules subject to an oscillating electric field,
using accurate potential curves and electronic transition dipole moments. We
show that for some particular wavelengths of the optical lattice, called "magic
wavelengths", the polarizability of the ground-state molecules is equal to the
one of a Feshbach molecule. As the creation of the sample of ground-state
molecules relies on an adiabatic population transfer from weakly-bound
molecules created on a Feshbach resonance, such a coincidence ensures that both
the initial and final states are favorably trapped by the lattice light,
allowing optimized transfer in agreement with the experimental observation
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