Hall coefficient and Hc2 in underdoped LaFeAsO0.95F0.05

The electrical resistivity and Hall coefficient of LaFeAsO0.95F0.05 polycrystalline samples were measured in pulsed magnetic fields up to m0H = 60 T from room temperature to 1.5 K. The resistance of the normal state shows a negative temperature coefficient (dr/dT < 0) below 70 K for this composition, indicating insulating ground state in underdoped LaFeAsO system in contrast to heavily doped compound. The charge carrier density obtained from Hall effect can be described as constant plus a thermally activated term with an energy gap DE = 630 K. Upper critical field, Hc2, estimated from resistivity measurements, exceeds 75 T with zero-field Tc = 26.3 K, suggesting an unconventional nature for superconductivity.Comment: 12 pages and 4 figure

The String Calculation of QCD Wilson Loops on Arbitrary Surfaces

Compact string expressions are found for non-intersecting Wilson loops in SU(N) Yang-Mills theory on any surface (orientable or nonorientable) as a weighted sum over covers of the surface. All terms from the coupled chiral sectors of the 1/N expansion of the Wilson loop expectation values are included.Comment: 10 pages, LaTeX, no figure

Facies architecture, emplacement mechanisms and eruption style of the submarine andesite El Barronal complex, Cabo de Gata, SE Spain

El Barronal complex consists of a succession of andesite lavas and andesite volcaniclastic facies interbedded with carbonate and siliciclastic sedimentary rocks. Carbonate and siliciclastic rocks were deposited in a shallow-marine environment during periods of volcanic quiescence. Lavas consist of an inner coherent core grading outward into hyaloclastite breccia made of dense clasts that in turn grade into hyaloclastite breccia made of vesicular clasts, in massive to layered zones. Volcaniclastic facies contain clasts produced during explosive eruptions and reworked clasts from sources above wave base. Volcaniclastic facies were deposited from cold granular flows with different grain size populations. Stratigraphy and facies architecture at El Barronal suggest that a succession of several discrete eruptive events occurred with a similar cyclic pattern made of an initial explosive phase followed by effusive emplacement of lavas, in turn followed by a period of quiescence of volcanic activity. Hyaloclastic fragmentation of magma took place in the final stages of lava emplacement, allowing only for local disorganization of the jigsaw-fit texture. © 2013 Elsevier B.V.This research has been funded by projects CGL2005-03511/BTE and HI2006-0073Peer Reviewe

Discovering the Relationship Between Investor Attention and Trade Volume in the Philippine Stock Exchange Using Google Search Analysis

This study investigates the relationship between daily Google search volume and trade volume in the Philippine Stock Exchange. This is completed by employing a sample consisting of listed stocks in the Philippine Stock Exchange from 2015 to 2019 and testing the veracity of three different keyword categories in proxying investor attention. The empirical results indicate that when using company names and stock tickers as Google search keywords, there is a strong positive relationship between Google search volume and trade volume. This implies that the more investors search for a stock’s company name or ticker, the more likely that there will be an increase in that stock’s trade volume the following day. Additionally, this study finds evidence that when using stock tickers as Google search keywords, aggregate investor sentiment can influence this relationship, such that it is more significant during periods of high consumer confidence. The findings support the notion that daily Google search volume can measure investor attention and potentially serve as a supplementary stock indicator for retail investors in the Philippine Stock Exchange

Discovering the Link between Investor Attention and Trade Volume in the Philippine Stock Exchange

Investors regard trade volume as a crucial technical indicator that can confirm trends, predict trend reversals, and determine liquidity (Westerhoff, 2006; Mahender et al., 2014). Trade volume is reported throughout the current trading day as often as once an hour; however, the reported hourly and end-of-the-day trade volumes are merely estimates. Actual and final trade volumes are reported the following day. Given the relative inconsistency of reported trade volumes and uncertainty of future trade volumes, investors miss the opportunity to reinforce their trading decisions through the trade volume indicator

Estimating Discharge in Low-Order Rivers With High-Resolution Aerial Imagery

Remote sensing of river discharge promises to augment in situ gauging stations, but the majority of research in this field focuses on large rivers (\u3e50 m wide). We present a method for estimating volumetric river discharge in low-order (wide) rivers from remotely sensed data by coupling high-resolution imagery with one-dimensional hydraulic modeling at so-called virtual gauging stations. These locations were identified as locations where the river contracted under low flows, exposing a substantial portion of the river bed. Topography of the exposed river bed was photogrammetrically extracted from high-resolution aerial imagery while the geometry of the remaining inundated portion of the channel was approximated based on adjacent bank topography and maximum depth assumptions. Full channel bathymetry was used to create hydraulic models that encompassed virtual gauging stations. Discharge for each aerial survey was estimated with the hydraulic model by matching modeled and remotely sensed wetted widths. Based on these results, synthetic width-discharge rating curves were produced for each virtual gauging station. In situ observations were used to determine the accuracy of wetted widths extracted from imagery (mean error 0.36 m), extracted bathymetry (mean vertical RMSE 0.23 m), and discharge (mean percent error 7% with a standard deviation of 6%). Sensitivity analyses were conducted to determine the influence of inundated channel bathymetry and roughness parameters on estimated discharge. Comparison of synthetic rating curves produced through sensitivity analyses show that reasonable ranges of parameter values result in mean percent errors in predicted discharges of 12%–27%

Pion-Nucleon Scattering in a Large-N Sigma Model

We review the large-N_c approach to meson-baryon scattering, including recent interesting developments. We then study pion-nucleon scattering in a particular variant of the linear sigma-model, in which the couplings of the sigma and pi mesons to the nucleon are echoed by couplings to the entire tower of I=J baryons (including the Delta) as dictated by large-N_c group theory. We sum the complete set of multi-loop meson-exchange \pi N --> \pi N and \pi N --> \sigma N Feynman diagrams, to leading order in 1/N_c. The key idea, reviewed in detail, is that large-N_c allows the approximation of LOOP graphs by TREE graphs, so long as the loops contain at least one baryon leg; trees, in turn, can be summed by solving classical equations of motion. We exhibit the resulting partial-wave S-matrix and the rich nucleon and Delta resonance spectrum of this simple model, comparing not only to experiment but also to pion-nucleon scattering in the Skyrme model. The moral is that much of the detailed structure of the meson-baryon S-matrix which hitherto has been uncovered only with skyrmion methods, can also be described by models with explicit baryon fields, thanks to the 1/N_c expansion.Comment: This LaTeX file inputs the ReVTeX macropackage; figures accompany i

Geologic map, volcanic stratigraphy and structure of the Cabo de Gata volcanic zone, Betic-Rif orogen, SE Spain

The geologic map of the Neogene Cabo de Gata volcanic zone is presented together with a comprehensive volcanic stratigraphy and structure based on logging, correlation and mapping. Volcanic rocks are interbedded with sedimentary rocks throughout the Cabo de Gata volcanic zone. The volcano-sedimentary succession of Cabo de Gata has been divided into formations according to lithology, age, composition and stratigraphic position. The contacts between sedimentary units and volcanic units and between formations are unconformities. Sedimentary units were deposited during periods of volcanic repose. The depositional environment of volcanism in Cabo de Gata is characterized as shallow-water submarine to emergent based on lithofacies of volcanic rocks and on fossil content and sedimentary structures of sedimentary rocks. The eruptive style in Cabo de Gata is dominantly effusive, although small-volume explosive eruptions due to magma-water interaction processes and to explosions of lava flow and domes complexes occurred.Peer Reviewe

Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics

The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this first installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of design methods and optical performance metrics developed for coronagraph instruments. The design and optimization of coronagraphs for future telescopes has progressed rapidly over the past several years in the context of space mission studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based telescopes. Design tools have been developed at several institutions to optimize a variety of coronagraph mask types. We aim to give a broad overview of the approaches used, examples of their utility, and provide the optimization tools to the community. Though it is clear that the basic function of coronagraphs is to suppress starlight while maintaining light from off-axis sources, our community lacks a general set of standard performance metrics that apply to both detecting and characterizing exoplanets. The attendees of the OOC workshop agreed that it would benefit our community to clearly define quantities for comparing the performance of coronagraph designs and systems. Therefore, we also present a set of metrics that may be applied to theoretical designs, testbeds, and deployed instruments. We show how these quantities may be used to easily relate the basic properties of the optical instrument to the detection significance of the given point source in the presence of realistic noise.Comment: To appear in Proceedings of the SPIE, vol. 1069