Flashing LEDs for microalgal production

Flashing lights are next-generation tools to mitigate light attenuation and increase the photosynthetic efficiency of microalgal cultivation systems illuminated by light-emitting diodes (LEDs). Optimal flashing light conditions depend on the reaction kinetics and properties of the linear electron transfer chain, energy dissipation, and storage mechanisms of a phototroph. In particular, extremely short and intense light flashes potentially mitigate light attenuation in photobioreactors without impairing photosynthesis. Intelligently controlling flashing light units and selecting electronic components can maximize light emission and energy efficiency. We discuss the biological, physical, and technical properties of flashing lights for algal production. We combine recent findings about photosynthetic pathways, self-shading in photobioreactors, and developments in solid-state technology towards the biotechnological application of LEDs to microalgal production.Foundation for Science and Technology (FCT, Portugal) [CCMAR/Multi/04326/2013]Nord UniversityNordland County Government (project Bioteknologi en framtidsrettet naering)INTERREG V-A Espana-Portugal project [0055 ALGARED + 5E]Portuguese Foundation for Science and Technology [SFRH/BD/105541/2014, SFRH/BD/115325/2016]info:eu-repo/semantics/publishedVersio

Control over stress induces plasticity of individual prefrontal cortical neurons: A conductance-based neural simulation

Behavioral control over stressful stimuli induces resilience to future conditions when control is lacking. The medial prefrontal cortex(mPFC) is a critically important brain region required for plasticity of stress resilience. We found that control over stress induces plasticity of the intrinsic voltage-gated conductances of pyramidal neurons in the PFC. To gain insight into the underlying biophysical mechanisms of this plasticity we used the conductance- based neural simulation software tool, NEURON, to model the increase in membrane excitability associated with resilience to stress. A ball and stick multicompartment conductance-based model was used to realistically fit passive and active data traces from prototypical pyramidal neurons in neurons in rats with control over tail shock stress and those lacking control. The results indicate that the plasticity of membrane excitability associated with control over stress can be attributed to an increase in Na+ and Ca2+ T-type conductances and an increase in the leak conductance. Using simulated dendritic synaptic inputs we observed an increase in excitatory postsynaptic summation and amplification resulting in elevated action potential output. This realistic simulation suggests that control over stress enhances the output of the PFC and offers specific testable hypotheses to guide future electrophysiological mechanistic studies in animal models of resilience and vulnerability to stress

Optical Surface Photometry of a Sample of Disk Galaxies. II Structural Components

This work presents the structural decomposition of a sample of 11 disk galaxies, which span a range of different morphological types. The U, B, V, R, and I photometric information given in Paper I (color and color-index images and luminosity, ellipticity, and position-angle profiles) has been used to decide what types of components form the galaxies before carrying out the decomposition. We find and model such components as bulges, disks, bars, lenses and rings.Comment: 14 figures. Accepted for publication in A&

Tres conceptos fundamentales en el debate litúrgico posconciliar: historia salutis – mysterium paschale – logiké latreía. Una aproximación al pensamiento litúrgico de Salvatore Marsili, Louis Bouyer y Joseph Ratzinger

El presente trabajo propone una aproximación a tres autores de gran importancia en el debate litúrgico posterior al Concilio Vaticano II: Salvatore Marsili, Louis Bouyer y Joseph Ratzinger. Marsili entiende la liturgia como un momento de la historia de la salvación, destacando así la continuidad entre los hechos salvíficos y el rito que los actualiza. Para valorar mejor sus aportes el estudio investiga la comprensión marsiliana de la historia de la salvación. En los escritos de Louis Bouyer la liturgia es comprendida como la «encarnación » del misterio de nuestra fe: el misterio pascual. A través de sus obras se identifican cuatro sentidos del misterio: como la naturaleza íntima de Dios; como su designio salvífico respecto del hombre y del mundo (sabiduría); como la realización de este designio en la cruz; y como misterio de culto en el cual los hombres somos convertidos en adoradores en espíritu y en verdad. Para Joseph Ratzinger la forma esencial del culto cristiano puede ser sintetizada en la expresión paulina logiké latreía (Rom 12,1). La referencia al «logos» en su teología constituye un fundamento sólido que permite distinguir tres dimensiones de la liturgia: cristológica, cósmica y cognoscitivo-existencial. En la liturgia el Logos encarnado, el logos en el mundo y el logos en el hombre se encuentran. El presente texto pone de manifiesto cómo los tres autores nos sitúan en la perspectiva histórico salvífica que propone Sacrosanctum Concilium y desarrolla el Catecismo de la Iglesia Católica.This work proposes an approach to three authors of great importance in the postconciliar liturgical debate: Salvatore Marsili, Louis Bouyer and Joseph Ratzinger. Marsili understands liturgy as a moment in the history of salvation, emphasizing the continuity between the salvific acts and the rites that actualizes them. To evaluate his contributions well, this study investigates the marsilian comprehension of the history of salvation. In the writings of Louis Bouyer, liturgy is understood as the «incarnation» of the mystery of our faith: the paschal mystery. In his works, four meanings of mystery can be identified: as the inner nature of God; as his salvific plan with respect to man and the world (wisdom); as the realization of this design on the cross; and as the mystery of worship in which we are transformed into adorers in spirit and truth. For Joseph Ratzinger, the essential form of christian worship can be synthetized in the Pauline expression logiké latreía (Rom 12, 1). The reference to the «logos» gives a solid foundation in his approach that permits a distinction of three dimensions of liturgy: christological, cosmical and cognoscitive- existential. In the liturgy, the incarnate Logos, the logos in the world, and the logos in man meet. This work highlights how the three authors position us in the historico-salvific perspective that Sacrosanctum Concilium proposes and the Catechism of the Catholic Church develop

Atmosphere Extinction at the ORM on La Palma: A 20 yr Statistical Database Gathered at the Carlsberg Meridian Telescope

The Observatorio del Roque de los Muchachos (ORM), in the Canary Islands (Spain), was one of the candidates to host the future European Extremely Large Telescope (E-ELT) and is the site of the Gran Telescopio Canarias (GTC), the largest optical infrared facility to date. Sky transparency is a key parameter as it defines the quality of the photometry to be acquired in the astronomical observations. We present a study of the atmosphere extinction at the ORM, carried out after analysis of a database spanning more than 20 yr, to our knowledge, the longest and most complete and homogeneous in situ database available for any observatory. It is based on photometric measurements in the V band and r' band (transformed to the V -band extinction coefficient kV) using the Carlsberg Meridian Telescope (CMT). Clear seasonal variations that repeat yearly are observed. The median value of kV is 0.13 mag/airmass; the mean value has a maximum in the summer months (June- September), corresponding to the season with maximum frequency of nights affected by dust or cirrus (~29% in summer, but only ~13% during the rest of the year). Two volcanic eruptions took place during the database baseline, which has enabled the study of the impact of volcanoes on the global atmosphere extinction. For the 5 yr of available information, we have estimated the average monthly weather downtime from the CMT data log, obtaining a result (20.7%) in reasonable agreement with earlier studies. The main conclusion of our study is that there is no significant evidence from the CMT data for any secular changes in kV over the 20 yr database baseline.Comment: 13 pages, 9 figures, 6 tables, published at PAS

Charged anisotropic matter with linear or nonlinear equation of state

Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplification achieved with the introduction of electric charge were noticed as well. We deal with self-gravitating, charged, anisotropic fluids and get even more flexibility in solving the Einstein-Maxwell equations. In order to discuss analytical solutions we extend Krori and Barua's method to include pressure anisotropy and linear or non-linear equations of state. The field equations are reduced to a system of three algebraic equations for the anisotropic pressures as well as matter and electrostatic energy densities. Attention is paid to compact sources characterized by positive matter density and positive radial pressure. Arising solutions satisfy the energy conditions of general relativity. Spheres with vanishing net charge contain fluid elements with unbounded proper charge density located at the fluid-vacuum interface. Notably the electric force acting on these fluid elements is finite, although the acting electric field is zero. Net charges can be huge ($10^{19}\,C$) and maximum electric field intensities are very large ($10^{23}-10^{24}\,statvolt/cm$) even in the case of zero net charge. Inward-directed fluid forces caused by pressure anisotropy may allow equilibrium configurations with larger net charges and electric field intensities than those found in studies of charged isotropic fluids. Links of these results with charged strange quark stars as well as models of dark matter including massive charged particles are highlighted. The van der Waals equation of state leading to matter densities constrained by cubic polynomial equations is briefly considered. The fundamental question of stability is left open.Comment: 22 Latex pages, 17 figures, Inclusion of new paragraph at the end of Conclusion & some of the old captions of the Figures are replaced with new caption

Effects of epitaxial strain on the growth mechanism of YBa2Cu3O7-x thin films in [YBa2Cu3O7-x / PrBa2Cu3O7-x] superlattices

We report on the growth mechanism of YBa2Cu3O7-x (YBCO). Our study is based on the analysis of ultrathin, YBa2Cu3O7-x layers in c-axis oriented YBa2Cu3O7-x / PrBa2Cu3O7-x superlattices. We have found that the release of epitaxial strain in very thin YBCO layers triggers a change in the dimensionality of the growth mode. Ultrathin, epitaxially strained, YBCO layers with thickness below 3 unit cells grow in a block by block two dimensional mode coherent over large lateral distances. Meanwhile, when thickness increases, and the strain relaxes, layer growth turns into three dimensional, resulting in rougher layers and interfaces.Comment: 10 pages + 9 figures, accepted in Phys. Rev.