8,754 research outputs found

    Excavaciones en la Unidad de Ejecución UE 1 del PRI del casco antiguo de Alcoy. Raval Vell de Alcoy

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    Es presenten els resultats de les excavacions urbanes realitzades al Raval Vell d’Alcoi en la Unitat d’Execució 1 del desenvolupament del Pla de Reforma Interior del nucli històric, amb la descripció més acurada dels estrats i estructures medievals localitzats. Paraules clau: Excavacions arqueològiques urbanes. Pla de Reforma Interior del nucli històric. Raval Vell d’Alcoi. Estructures medievals.We present the results of the urban excavations carried out in the “Raval Vell” of Alcoy in the Execution Unit 1 developing the Interior Reform Projectof the historical city centre with a most detailed description of the medieval strata and structures which have been found. Key words: Urban archaeological excavations. Interior Reform Project of the historical city centre. The Old Suburb of Alcoy. Medieval structures.En este artículo presentamos los resultados de la excavación arqueológica de urgencia llevada a cabo en los solares situados en la Placeta del Fossar nº 4 y Sant Blai nº 16. El hallazgo más significativo de esta excavación es un vertedero con materiales que van de finales del s. XVI al s. XVII. Palabras clave: Excavación arqueológica urbana. Placeta del Fossar. Vertedero. Siglos XVI-XVII. Alcoy

    Validity evidence of the organizational justice scale in Spain

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    Resumen tomado de la publicaciónEvidencias de validez de la Escala de Justicia Organizacional en España. Antecedentes: el interés por la medición de la percepción de justicia organizacional ha aumentado en los últimos años debido a su demostrada relación con resultados organizacionales significativos, como el bienestar y el agotamiento emocional. En España, se puede destacar la Escala de Justicia Organizacional (OJS) como un instrumento que ha mostrado buenas propiedades psicométricas en estudios previos en el sector hotelero. Este estudio complementa la evidencia de las características de la OJS utilizando una amplia muestra multisectorial. Método: los participantes fueron 849 empleados de diferentes sectores ocupacionales. La estructura de la OJS se estudió mediante análisis factorial exploratorio y confirmatorio dividiendo la muestra en dos submuestras aleatorias. Además, se analizó la fiabilidad y validez de cada dimensión. Resultados: los resultados indicaron que la escala está constituida por tres factores (distributiva, procedimental y en la interacción), con una fiabilidad y validez adecuadas. Por otra parte, como era de esperar, se encontraron correlaciones positivas entre la percepción de justicia organizacional y el bienestar, y negativas con el agotamiento emocional. Conclusiones: la OJS es una herramienta adecuada para su uso por parte de académicos y profesionales en el estudio de la percepción de justicia organizacional en España, garantizando una validez y fiabilidad adecuadas.Universidad de Oviedo. Biblioteca de Psicología; Plaza Feijoo, s/n.; 33003 Oviedo; Tel. +34985104146; Fax +34985104126; [email protected]

    Perturbative contributions to Wilson loops in twisted lattice boxes and reduced models

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    We compute the perturbative expression of Wilson loops up to order g4g^4 for SU(NN) lattice gauge theories with Wilson action on a finite box with twisted boundary conditions. Our formulas are valid for any dimension and any irreducible twist. They contain as a special case that of the 4-dimensional Twisted Eguchi-Kawai model for a symmetric twist with flux kk. Our results allow us to analyze the finite volume corrections as a function of the flux. In particular, one can quantify the approach to volume independence at large NN as a function of flux kk. The contribution of fermion fields in the adjoint representation is also analyzed.Comment: pdflatex 57 pages, 9 figures, 4 appendice

    Effect of elevated inorganic carbon on the cytosolic homeostasis of NO3- in the marine angiosperm Posidonia oceanica (L.) Delile

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    The marine angiosperm Posidonia oceanica is a mediterranean endemism of great ecological significance. As other marine plants, P. oceanica has adapted secondarily to the marine environment and develop anew different mechanisms to colonize it. Among others, this plant has developed a plasma membrane system for the direct uptake of bicarbonate. In this work we have developed both NO3- and Cl- selective microelectrodes for the continuous monitoring of the intracellular (cytosolic) NO3- and Cl-. In the light, leaf mesophyll cells show a cytosolic NO3- concentration of 5.7±0.2 mM (n=10), while in the dark cytosolic NO3- raises up to 8.7±1.1 mM; these values are in the range of concentrations quoted for Arabidopsis thaliana (Cookson et al., 2005). The enrichment of natural seawater (NSW) with 3 mM NaHCO3 caused a decrease of the cytosolic NO3- concentration of 1 mM and a decrease of the cytosolic concentration of Cl- of 3.5 mM. The saturation of NSW with 1000 µL CO2 L-1 produced a lower diminution of the cytosolic NO3- (0.3 mM). In the presence of 0.1 mM of the plasma membrane permeable inhibitor of the carbonic anhydrase (EZ) the diminution of cytosolic NO3- caused by the same concentration of CO2 was much lower, 0.1 mM. The addition of inorganic carbon, either HCO3- or CO2, has an effect on the cytosolic mechanisms for anionic homeostasis, one of which is the opening of the slow anion channels. These channels are permeable to NO3- and Cl- and could elicit the efflux of these ions. In P. oceanica, the response in the presence of EZ points out that the inorganic carbon species that cause the NO3-/Cl- efflux is HCO3-. This effect could contribute to plant biomass N dilution observed in elevated CO2. References: Cookson et al. 2005. Plant Physiology 138, 1097–1105.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

    HCO3- enrichment causes cytosolic NO3- efflux in Posidonia oceanica leaf cells

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    Posidonia oceanica is a seagrass, the only group of vascular plants to colonize the marine environment. Seawater is an extreme yet stable environment, characterized by high salinity, alkaline pH and low availability of essential nutrients, such as nitrate or phosphate. In addition, in aquatic environments the supply of CO2 for the photosynthesis is limited by diffusion and therefore many aquatic plants use HCO3- as the inorganic carbon source for photosynthesis. Previous results have shown that Na+ -dependent transport systems operate on the plasma membrane of P. oceanica mesophyll leaf cells for the high-affinity NO3-, Pi or amino acids uptake. Also, a direct transport of HCO3- driven by H+ has been found in this species that provides inorganic carbon for photosynthesis and could be a significant component of a carbon concentrating mechanism in this species. Interestingly, this HCO3- direct uptake caused the efflux of chloride from the cytosol, probably through S-type anion channels, pointing that other anions could also be removed from the cytosol. This hypothesis could be relevant in the case of NO3-, since the decrease of cytosolic NO3- in response to HCO3- enrichment could limit N-assimilation. Here we analyse the effect of HCO3- increase on NO3- uptake and cytosolic homeostasis in P. oceanica. Enrichment of natural seawater with 3 mM HCO3- evokes the on-going decrease of cytosolic NO3-, from 5.7 ± 0.2 to 4.8 ± 0.7 mM after 40 min of treatment. The incubation of P. oceanica leaf pieces in 3 mM HCO3- NSW causes an initial increase of NO3- concentration in the medium. Maximum efflux (21 nmol NO3- gFM-1 min-1) occurs within the first minute of incubation. Then, external NO3- is depleted from the medium at lower net uptake rate than the value observed in non HCO3- -enriched natural seawater. These results fit the hypothesis that HCO3- enrichment causes the nitrogen loose and could impair nitrogen assimilation promoting N biomass impoverishment.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Spanish MINECO, projects BFU2017-85117-R and BIO2016-81957-RED

    Na+-dependent NO3- uptake in leaf cells of the seagrass Posidonia oceanica (L.) Delile

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    Posidonia oceanica (L.) Delile is an endemic Mediterranean seagrass of recognized ecological significance and, as other seagrasses, this species has secondarily adapted to live in the marine environment. In this alkaline medium with a high Na+ concentration (0.5 M), the high inwardly directed electrochemical potential gradient for sodium is used in the seagrass Zostera marina to energize the uptake of nitrate1 and phosphate that usually occur at concentration below 10 µM. Here we summarize several evidences for the operation of a sodium-dependent high-affinity nitrate transport system at the plasma membrane of the mesophyll leaf cells of P. oceanica. Leaf cells of P. oceanica possess a H+-ATPase as a primary pump, exhibit a plasma membrane potential (Em) of -174 ± 10 mV and show reduced Na+ permeability. The addition of micromolar nitrate concentrations induces membrane depolarizations that show saturation kinetics. Curve fitting of the values renders a semisaturation constant (Km) of 21.3 ± 6.6 μM and a maximum depolarization (Dmax) of 7 ± 1 mV. In dark conditions, Dmax decreases by fifty percent but no significant effect is observed on the Km value. On the other hand, nitrate induced depolarizations show sodium dependence. The depolarizations induced by 100 µM NO3- in media containing increasing Na+ concentrations (from 0 to 250 mM) show saturation kinetics, rendering a Km value of 16 ± 5 mM Na+. Moreover, the depolarization induced by 100 µM NO3- is accompanied by a simultaneous increase of cytosolic sodium, measured by Na+-sensitive microelectrodes, of 0.4 ± 0.2 mM above the resting cytosolic sodium concentration (17 ± 2 mM). Finally, nitrate uptake rates, measured in depletion experiments, decreases by 50% and 80% in dark conditions and in the absence of Na+, respectively, compared with control conditions (0.5 M Na+ and light). All together, these results strongly suggest that NO3- uptake in P. oceanica leaf cells is mediated by a high-affinity nitrate carrier that uses Na+ as the driving ion. 1 Rubio et al. (2005). J. Exp. Bot, 412: 613-622. Project Funding: CTM 2011-30356. (MEC)Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    The SU()SU(\infty) twisted gradient flow running coupling

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    We measure the running of the SU()SU(\infty) 't Hooft coupling by performing a step scaling analysis of the Twisted Eguchi-Kawai (TEK) model, the SU(NN) gauge theory on a single site lattice with twisted boundary conditions. The computation relies on the conjecture that finite volume effects for SU(N) gauge theories defined on a 4-dimensional twisted torus are controlled by an effective size parameter l~=lN\tilde l = l \sqrt{N}, with ll the torus period. We set the scale for the running coupling in terms of l~\tilde l and use the gradient flow to define a renormalized 't Hooft coupling λ(l~)\lambda(\tilde l). In the TEK model, this idea allows the determination of the running of the coupling through a step scaling procedure that uses the rank of the group as a size parameter. The continuum renormalized coupling constant is extracted in the zero lattice spacing limit, which in the TEK model corresponds to the large NN limit taken at fixed value of λ(l~)\lambda(\tilde l). The coupling constant is thus expected to coincide with that of the ordinary pure gauge theory at N=N =\infty. The idea is shown to work and permits us to follow the evolution of the coupling over a wide range of scales. At weak coupling we find a remarkable agreement with the perturbative two-loop formula for the running coupling.Comment: 22 pages, 7 figure
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