Steady-state signatures of radiation trapping by cold multilevel atoms

In this paper, we use steady-state measurements to obtain evidence of radiation trapping in an optically thick a cloud of cold rubidium atoms. We investigate the fluorescence properties of our sample, pumped on opened transitions. The intensity of fluorescence exhibits a non trivial dependence on the optical thickness of the media. A simplified model, based on rate equations self-consistently coupled to a diffusive model of light transport, is used to explain the experimental observations in terms of incoherent radiation trapping on one spectral line. Measurements of atomic populations and fluorescence spectrum qualitatively agree with this interpretation.Comment: 8 pages, 5 figure

Simulations of Melting of Encapsulated CaCl2·6H2O for Thermal Energy Storage Technologies

We present in this work simulations using the finite difference approximation in 2D for the melting of an encapsulated phase-change material suitable for heat storage applications; in particular, we study CaCl2·6H2O in a cylindrical encapsulation of internal radius 8 mm. We choose this particular salt hydrate due to its availability and economic feasibility in high thermal mass building walls or storage. Considering only heat conduction, a thermostat is placed far from the capsule, providing heat for the melting of the phase-change material (PCM), which is initially frozen in a water bath. The difference in density between the solid and liquid phases is taken into account by considering a void in the solid PCM. A simple theoretical model is also presented, based on solving the heat equation in the steady state. The kinetics of melting is monitored by the total solid fraction and temperatures in the inner and outer surfaces of the capsule. The effect of different parameters is presented (thermostat temperature, capsule thickness, capsule conductivity and natural convection in the bath), showing the potential application of the method to select materials or geometries of the capsule

Corporate social responsibility and the assessment by auditors of the risk of material misstatement

This paper investigates whether, and how, firms’ corporate social responsibility (CSR) performance influences the auditor's assessment of the risk of material misstatement, whether due to fraud or error, at the financial statement level by analysing their pricing decision (i.e., audit fees). Using a panel data set of 12,330 firms from 28 countries over the period 2003–2012 and different measures of CSR performance, we find a U-shaped relationship between firms’ CSR performance and audit fees. This result suggests that there is an optimal level of CSR performance that minimizes the auditor's assessment of the risk of material misstatement, which in turn lowers the need for greater auditor effort; that is why auditors charge firms significantly less when their CSR performance is at the optimal level. Finally, we also show that the optimal level of CSR performance varies with the degree of environmental dynamism, ownership concentration and leverage.The authors also acknowledge support from the Fundación Ramon Areces, Projects ECO2013-48328-C03-3-P, ECO2013-45864-P, ECO2014-57131-R, ECO2016-75961-R and ECO2016-77579-C3-2-P financed by the Spanish Ministry of Science and Innovation and project INNCOMCON-CM(S2015/HUM-3417)

Studies of the early medieval pottery of Al-Andalus

Se adjunta el archivo de las pruebas de imprenta. "The definitive version is available at www.blackwell-synergy.com"This paper presents a review of the studies of early medieval (Amiral and Caliphal) pottery in al-Andalus. It opens with a discussion of the first archaeological and ceramics surveys, including an assessment of their historical and theoretical contexts and their relevance to the developing discipline. After discussion of the contributions and also shortcomings of current approaches, the article closes by sketching the direction of future research

Sociotechnical options of irrigation and dry agriculture: case study of the Vega of Granada

En el archivo adjunto se incluye la versión del artículo previa a su publicación y la traducción al inglés.En este artículo los autores hemos combinado nuestra experiencia en el estudio de la cerámica altomedieval y de los paisajes de regadío y hemos propuesto un modelo teórico para explicar el desarrollo del regadío en España a costa de los espacios de agricultura de secano. Nuestro modelo se basa en los conceptos de "antropología social de la tecnología" de B. Pfaffenberger y "habitus" de P. Bourdieu.In this paper the authors have combined our experience in the study of early medieval pottery and irrigation landscapes and have proposed a theoretical model to explain the enabling of irrigation in Spain at the expense of the spaces of dry agriculture. Our model draws concepts from B. Pfaffenberger's "Social Anthropology of Technology" and P. Bourdieu's "habitus"

Concepciones de práctica pedagógica de las estudiantes de VIII semestre de la Licenciatura en Pedagogía Infantil

Para este proyecto se tuvieron en cuenta dos grandes fundamentos teóricos: concepciones y prácticas pedagógicas. Desde el primero se explica qué es una concepción y la evolución que ha tenido este concepto desde la construcción del conocimiento: individual y social. Referenciando como el individuo participa de manera individual y social, en la adquisición de sus propias concepciones sobre el mundo que lo rodea. Además hay diferentes enfoques que lo complementa como: la metacognición, la teoría de la mente, las creencias epistemológicas, el fenomenográfico y las teorías implícitas y explícitas. De todos estos enfoques en esta investigación se acoge el de las teorías implícitas, las cuales son importantes ya que evidencian el proceso de construcción de las comprensiones que se tienen las estudiantes del mundo desde los discursos y las actuaciones. Y desde el segundo, se explican las prácticas pedagógicas como acciones que el maestro realiza dentro del aula y la relación que existe entre la práctica y la teoría. De estas actuaciones a través de la historia se han construidos varias concepciones, las cuales fueron nombradas en el primer párrafo. La artesanal o concepción tradicional-oficio, la normalizadora-disciplinadora, la academicista, la técnico academicista, la humanista, y la hermenéutico reflexivo. Además se expone la forma como se entienden las prácticas pedagógicas en el currículo de Pedagogía Infantil. La cual se comprende desde cuatro ejes que constituyen y articulan los diferentes procesos de la formación de la futura licenciada en Pedagogía infantil: el primer eje referido a la identidad, el segundo a el saber, el tercero al quehacer y el último a la reflexión. En este apartado de las prácticas pedagógicas también se vinculan las dimensiones de la formación docente: disciplinar, procedimental, estratégica y ético- política. Las cuales apuntan a que el docente articule todas estas en su quehacer. La metodología implementada en esta investigación es cualitativa de corte interpretativo, para la cual se utilizaron dos instrumentos, la entrevista semiestructurada y la observación no participante, estos se aplicaron en cinco estudiantes de VIII semestre, las cuales realizaron su práctica pedagógica en la institución educativa Ciudad Boquía, ubicado en el barrio “Parque industrial” en la ciudad de Pereira

Bridging accounting and corporate governance: new avenues of research

This paper draws on the articles in the Forum on Corporate Governance to discuss how corporate governance and accounting research complement each other well in explaining how companies are governed as well as properly managed from an accounting point of view. We put special attention to the cross-national differences in both corporate governance systems and accounting practice and how that affect multiple organizational outcomes ranging from financial performance to corporate social performance and reporting quality

HEPPA-II model-measurement intercomparison project: EPP indirect effects during the dynamically perturbed NH winter 2008-2009

Funke, B. et. al..--This work is distributed under the Creative Commons Attribution 3.0 License.We compare simulations from three high-top (with upper lid above 120 km) and five medium-top (with upper lid around 80 km) atmospheric models with observations of odd nitrogen (NOx D NO+NO2), temperature, and carbon monoxide from seven satellite instruments (ACE-FTS on SciSat, GOMOS, MIPAS, and SCIAMACHY on Envisat, MLS on Aura, SABER on TIMED, and SMR on Odin) during the Northern Hemisphere (NH) polar winter 2008/2009. The models included in the comparison are the 3-D chemistry transport model 3dCTM, the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMO-NIA), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA), the modelling tools for SOlar Climate Ozone Links studies (SOCOL and CAO-SOCOL), and the Whole Atmosphere Community Climate Model (WACCM4). The comparison focuses on the energetic particle precipitation (EPP) indirect effect, that is, the polar winter descent of NOx largely produced by EPP in the mesosphere and lower thermosphere. A particular emphasis is given to the impact of the sudden stratospheric warming (SSW) in January 2009 and the subsequent elevated stratopause (ES) event associated with enhanced descent of mesospheric air. The chemistry climate model simulations have been nudged toward reanalysis data in the troposphere and stratosphere while being unconstrained above. An odd nitrogen upper boundary condition obtained from MIPAS observations has further been applied to medium-top models. Most models provide a good representation of the mesospheric tracer descent in general, and the EPP indirect effect in particular, during the unperturbed (pre-SSW) period of the NH winter 2008/2009. The observed NOx descent into the lower mesosphere and stratosphere is generally reproduced within 20 %. Larger discrepancies of a few model simulations could be traced back either to the impact of the models' gravity wave drag scheme on the polar wintertime meridional circulation or to a combination of prescribed NOx mixing ratio at the uppermost model layer and low vertical resolution. In March-April, after the ES event, however, modelled mesospheric and stratospheric NOx distributions deviate significantly from the observations. The too-fast and early downward propagation of the NO x tongue, encountered in most simulations, coincides with a temperature high bias in the lower mesosphere (0.2-0.05 hPa), likely caused by an overestimation of descent velocities. In contrast, upper-mesospheric temperatures (at 0.05-0.001 hPa) are generally underestimated by the high-top models after the onset of the ES event, being indicative for too-slow descent and hence too-low NOx fluxes. As a consequence, the magnitude of the simulated NOx tongue is generally underestimated by these models. Descending NOx amounts simulated with mediumtop models are on average closer to the observations but show a large spread of up to several hundred percent. This is primarily attributed to the different vertical model domains in which the NOx upper boundary condition is applied. In general, the intercomparison demonstrates the ability of state-of- the-art atmospheric models to reproduce the EPP indirect effect in dynamically and geomagnetically quiescent NH winter conditions. The encountered differences between observed and simulated NOx, CO, and temperature distributions during the perturbed phase of the 2009 NH winter, however, emphasize the need for model improvements in the dynamical representation of elevated stratopause events in order to allow for a better description of the EPP indirect effect under these particular conditions.This work has been conducted in the frame of the WCRP/ SPARC SOLARIS-HEPPA activity. The IAA team was supported by the Spanish MCINN under grant ESP2014-54362-P and EC FEDER funds. The MPI-MET team was supported by the Max Planck Gesellschaft (MPG), and computational resources were made available by Deutsches Klimarechenzentrum (DKRZ) through support from Bundesministerium fur Bildung und Forschung (BMBF). The FMI team was supported by the Academy of Finland through the projects 276926 (SECTIC: Sun-Earth Connection Through Ion Chemistry), 258165, and 265005 (CLASP: Climate and Solar Particle Forcing). CAO team was supported by the Russian Science Foundation under grant 15-17-10024. SOCOL team was funded by Swiss National Science Foundation (SNSF) grants 200021-149182 (SILA), 200020-163206 (SIMA), and CRSII2-147659 (FUPSOL-II). S. Bender, M. Sinnhuber, and H. Nieder (all KIT) gratefully acknowledge funding by the Helmholtz Association of German Research Centres (HGF), grant VH-NG-624. NCAR is sponsored by the National Science Foundation (NSF). Computing resources for WACCM simulations were provided by the Climate Simulation Laboratory at NCAR's Computational and Information Systems Laboratory, sponsored by the NSF and other agencies. Work at the Jet Propulsion Laboratory, California Institute of Technology, was carried out under a contract with the National Aeronautics and Space Administration. The Atmospheric Chemistry Experiment (ACE), also known as SciSat, is a Canadian-led mission mainly supported by the Canadian Space Agency. Odin is a Swedish-led satellite project funded jointly by Sweden (SNSB), Canada (CSA), Finland (TEKES), and France (CNES) and is part of European Space Agency's (ESA) third-party mission program. We thank two anonymous reviewers for helpful suggestions that led to improvements in the quality of the present work.Peer reviewe

MEPSAnd: Minimum Energy Path Surface Analysis over n-dimensional surfaces.

Summary: Understanding biophysical phenomena from the approach of molecular simulation is becoming the state-of-art in many research and technology development fields. Energy surfaces with more than 3 dimensions (2 coordinates and energy) are now computationally accessible, yet interpreting the information they offer is not straightforward and the tasks involved very time-consuming. Here we present MEPSAnd, an open source GUI-based program that natively calculates minimum energy paths across energy surfaces of an arbitrary number of dimensions. In addition to the multidimensional analysis of path through lowest barriers, MEPSAnd can also automatically calculate a finite series of suboptimal paths. To allow the efficient interpretation of results, MEPSAnd offers three distinct plotting solutions: i) energy profiles, ii) coordinate projections and iii) network projections. GUI-independent pipelines are also supported via direct python scripting. Therefore, MEPSAnd is a powerful user friendly tool that streamlines path-finding tasks on n-dimensional energy surfaces.pre-print1996 K