Relaxation oscillations, pulses, and travelling waves in the diffusive Volterra delay-differential equation

The diffusive Volterra equation with discrete or continuous delay is studied in the limit of long delays using matched asymptotic expansions. In the case of continuous delay, the procedure was explicitly carried out for general normalized kernels of the form Sigma/sub n=p//sup N/ g/sub n/(t/sup n//T/sup n+1/)e/sup -t/T/, pges2, in the limit in which the strength of the delayed regulation is much greater than that of the instantaneous one, and also for g/sub n/=delta/sub n2/ and any strength ratio. Solutions include homogeneous relaxation oscillations and travelling waves such as pulses, periodic wavetrains, pacemakers and leading centers, so that the diffusive Volterra equation presents the main features of excitable media

Characterization of TrxC, an Atypical Thioredoxin Exclusively Present in Cyanobacteria

Cyanobacteria form a diverse group of oxygenic photosynthetic prokaryotes considered to be the antecessor of plant chloroplast. They contain four different thioredoxins isoforms, three of them corresponding to m, x and y type present in plant chloroplast, while the fourth one (named TrxC) is exclusively found in cyanobacteria. TrxC has a modified active site (WCGLC) instead of the canonical (WCGPC) present in most thioredoxins. We have purified it and assayed its activity but surprisingly TrxC lacked all the classical activities, such as insulin precipitation or activation of the fructose-1,6-bisphosphatase. Mutants lacking trxC or over-expressing it were generated in the model cyanobacterium Synechocystis sp. PCC 6803 and their phenotypes have been analyzed. The ΔtrxC mutant grew at similar rates to WT in all conditions tested although it showed an increased carotenoid content especially under low carbon conditions. Overexpression strains showed reduced growth under the same conditions and accumulated lower amounts of carotenoids. They also showed lower oxygen evolution rates at high light but higher Fv’/Fm’ and Non-photochemical-quenching (NPQ) in dark adapted cells, suggesting a more oxidized plastoquinone pool. All these data suggest that TrxC might have a role in regulating photosynthetic adaptation to low carbon and/or high light conditions.España, MINECO BIO2016-75634-PJunta de Andalucía P12-BIO-1119 , BIO-28

The Productivity Paradox and the New Economy: The Spanish Case

This paper studies the impact of the information and communication technologies (ICT) on economic growth in Spain using a dynamic general equilibrium approach. Contrary to previous works, we use a production function with six different capital inputs, three of them corresponding to ICT assets. Calibration of the model suggests that the contribution of ICT to Spanish productivity growth is very relevant, whereas the contribution of non-ICT capital has been even negative. Additionally, over the sample period 1995-2002, we find a negative TFP and productivity growth. These results together aim at the hypothesis that the Spanish economy could be placed within the productivity paradox.New economy, information and communication technologies, technological change, productivity paradox.

ICT-specific technological change and productivity growth in the US 1980-2004

This paper studies the impact of the information and communication technologies (ICT) on U.S. economic growth using a dynamic general equilibrium approach. We use a production function with six different capital inputs, three of them corresponding to ICT assets and other three to non-ICT assets. We find that the technological change embedded in hardware equipment is the main leading non-neutral force of the U.S. productivity growth and accounts for about one quarter of it during the period 1980-2004. As a whole, ICT-specific technological change accounts for about 35% of total labor productivity growth.New economy, information and communication technologies, specific-technological change, neutral-technological change.

El patrimonio rústico de los jesuitas en España. Una aproximación

A pesar de su tardía configuración, la Compañía de Jesús logró reunir un importante patrimonio rústico en España que destacó más por su calidad que por su superficie. En la formación de dicho dominio las compras jugaron un papel muy importante, a diferencia de otras órdenes religiosas, en las que predominaron las donaciones. La explotación de este dominio rural, en él que predominó la gestión directa, estaba orientada, sobre todo, a la comercialización de la producción y menos al consumo de las comunidades regulares. Por tanto, en dicha gestión primarion criterios de rentabilidad económica. Por último, tras su expulsión de España en 1767, las propiedades de los jesuitas fueron incautadas por el estado y posteriormente vendidas en subasta en un proceso que anticipa las desamortizaciones eclesiásticas del siglo XIX.In spice of its late formation, the Company of Jesus managed to amass an important rural patrimony in Spain, more notable for its quality than for its area. In contrast with other religious orders, for whom donations were dominât, purchases played a very important role in the formation of this patrimony. The exploitation of this rural domain, in which direct management was the norm, was oriented primarily towards the commercialisation of production and less towards consumption by the religious community itself. Therefore, management was dictated principally by criteria of economic profitability. Finally, after the Jesuit's expulsion from. Spain in 1767, their properties were seized by the state and subsequently put up for public auction in a process that anticipates the ecclesiastical demortization of the nineteenth centur

Explotaciones agrarias de la orden cartuja

A lo largo de los siglos la administración de los dominios conventuales ha tratado de adecuarse a los cambios habidos en la coyuntura económica. Estas transformaciones en la gestión tuvieron como principal objetivo un incremento de los beneficios. Con el análisis de las explotaciones practicadas por los cartujos andaluces tratamos de mostrar como los principales cambios habidos en la gestión de su patrimonio, reducción de los plazos de arrendamiento, sustitución de la renta en especie por renta en metálico, introducción de cultivos de mayor rentabilidad económica y, por último, la explotación directa, que permite diversificar las fuentes de ingresos, se produjo un notable incremento de los beneficios monásticos

Una élite rural. Los grandes ganaderos andaluces, siglos XIV-XX

En las grandes explotaciones agrarias de la Baja Andalucía la ganadería jugaba un papel tan importante como los cultivos agrícolas. En este tipo de explotaciones la ganadería estaba estrechamente vinculada a la agricultura a là que suministraba trabajo, abonos y dinero en metálico, al tiempo que los ganados se beneficiaban de los barbechos y de los residuos de las cosechas. Dada esta vinculación las figuras del gran agricultor y gran ganadero se fundían en una misma persona que era la del gran labrador que dirigía la explotación agraria. Este gran labrador aprovechaba su importancia económica y social para imponer su poder en los concejos municipales, a fin de inclinar en su propio beneficio la explotación de los espacios rurales colectivos en los que mantenía su ganado durante buena parte del año.In the largest estates of Lower Andalusia, livestock farming played a role as important as arable agriculture. In these kinds of estates, livestock farming was closely bound to agriculture, supplying the latter with employment, fertiliser, and cash. At the same time, cattle farming made use of fallow land and of the remnants of the harvests. Due to this link, the figures of the great cattle-owner and the great agriculturalist were blended together into that of the big farmer in charge of his estates. Such a farmer profited from his economic and social status, imposing his authority on the town councils, so as to incline to his own benefit the exploitation of collective rural spaces in which livestock were fed during most of the yea