Effect of temperature, dissolved inorganic carbon and light intensity on the growth rates of two microalgae species in monocultures and co-cultures

textThe enormous biodiversity of microalgae as well as their high photosynthetic rates can be exploited for a wide variety of applications including the production of high value chemicals, nutraceuticals, aquaculture feed, and most recently, biofuels. Regardless of the application, the productivity of the microalgae culture must be optimized in order to make the systems economically feasible. One environmental factor that greatly affects the productivity of mass cultivation systems is temperature since it can be prohibitively expensive to control in outdoor systems. Temperature affects microalgae growth rates both directly by its effect on metabolic rates, and indirectly, by changing the bioavailability of the inorganic carbon present in solution. In the first part of this research, the effects of dissolved inorganic carbon (DIC) concentration (varied by sparging CO₂-enriched air) and temperature on the growth of a model microalga species (Nannochloris sp., UTEX LB1999) were investigated in a turbidostat bioreactor. The results indicate that increasing DIC concentration yields higher microalgae growth rates up to an optimum value (around 3 mM for Nannochloris sp.) but higher concentrations actually inhibited growth. Since increasing the temperature decreases the DIC concentration for a given gas pCO₂, it is necessary to adjust the pCO₂ to maintain the target DIC concentration in the optimal range for growth. In the next phase of the research, the effect of average light intensity (Gav) and temperature on the growth rate of two microalgae species (Nannochloris sp., UTEX1999. and Phaeodactylum tricornutum, UTEX646) was investigated. Growth rates were measured over a range of average light intensities and temperatures using a turbidostat bioreactor. A multiplicative model was developed to describe growth as a function of both average light intensity and temperature. In the third phase of this research, both microalgae species were grown together to explore the effects of temperature fluctuations on the population dynamics of the co-culture. It was observed that Nannochloris was inhibited by the presence of P. tricornutum in the medium, probably due to the excretion of secondary metabolites into the medium that affected Nannochloris growth (allelopathic effects). The temperature and average light intensity model developed under monoculture conditions was modified to incorporate the allelopathic effects observed. The resulting model provided a reasonable fit to the dynamic behavior of a Nannochloris/P. tricornutum co-culture subjected to temperature variations in chemostat experiments.Civil, Architectural, and Environmental Engineerin

On the Empirics of Sudden Stops: The Relevance of Balance-Sheet Effects

Using a sample of 32 developed and developing countries we analyze the empirical characteristics of Sudden Stops in capital flows and the relevance of balance-sheet effects in the likelihood of their occurrence. We find that large real exchange rate (RER) fluctuations accompanied by Sudden Stops are basically an emerging market (EM) phenomenon. Sudden Stops seem to come in bunches, grouping together countries that are different in many respects. However, countries are similar in that they remain vulnerable to large RER fluctuations. This may be the case because countries are forced to make large adjustments in the absorption of tradable goods, and/or because the size of dollar liabilities in the banking system (i. e. , domestic liability dollarization, or DLD) is large. Openness, understood as a large supply of tradable goods that reduces leverage over the current account deficit, in combination with DLD, is a key determinant of the probability of Sudden Stops. The relationship between Openness and DLD in the determination of the probability of Sudden Stops is highly non-linear, implying that the interaction of high current account leverage and high dollarization may be a dangerous cocktail.

Systemic Sudden Stops: The Relevance of Balance-Sheet Effects and Financial Integration

Using a sample of 110 developed and developing countries for the period 1990-2004, this paper analyzes the characteristics of systemic sudden stops (3S) in capital flows and the relevance of balance-sheet effects in the likelihood of their materialization. A small supply of tradable goods relative to their domestic absorption?a proxy for potential changes in the real exchange rate?and large foreign-exchange denominated debts towards the domestic banking system are claimed to be key determinants of the probability of 3S, producing a balancesheet effect with non-linear impacts on the probability of 3S. While financial integration is up to a point associated with a higher likelihood of 3S, beyond that point financial integration is associated with a lower likelihood of 3S.

On the Empirics of Sudden Stops: The Relevance of Balance-Sheet Effects

Using a sample of 32 developed and developing countries we analyze the empirical characteristics of sudden stops in capital flows and the relevance of balance sheet effects in the likelihood of their materialization. We find that large real exchange rate (RER) fluctuations coming hand in hand with Sudden Stops are basically an emerging market (EM) phenomenon. Sudden Stops seem to come in bunches, grouping together countries that are different in many respects. However, countries are similar in that they remain vulnerable to large RER fluctuations – be it because they could be forced to large adjustments in the absorption of tradable goods, and/or because the size of dollar liabilities in the banking system (i.e., domestic liability dollarization, or DLD) is high. Openness, understood as a large supply of tradable goods that reduces leverage over the current account deficit, coupled with DLD, are key determinants of the probability of Sudden Stops. The relationship between Openness and DLD in the determination of the probability of Sudden Stops is highly non-linear, implying that the interaction of high current account leverage and high dollarization may be a dangerous cocktail.

Dual branes in topological sigma models over Lie groups. BF-theory and non-factorizable Lie bialgebras

We complete the study of the Poisson-Sigma model over Poisson-Lie groups. Firstly, we solve the models with targets $G$ and $G^*$ (the dual group of the Poisson-Lie group $G$) corresponding to a triangular $r$-matrix and show that the model over $G^*$ is always equivalent to BF-theory. Then, given an arbitrary $r$-matrix, we address the problem of finding D-branes preserving the duality between the models. We identify a broad class of dual branes which are subgroups of $G$ and $G^*$, but not necessarily Poisson-Lie subgroups. In particular, they are not coisotropic submanifolds in the general case and what is more, we show that by means of duality transformations one can go from coisotropic to non-coisotropic branes. This fact makes clear that non-coisotropic branes are natural boundary conditions for the Poisson-Sigma model.Comment: 24 pages; JHEP style; Final versio

Validación de la Escala de Vínculos Interpersonales de Apoyo VIDA.

Social Support is one of the most well documented factors influencing health outcomes. Cultural differences and language use between Spain and other Spanish-speaking countries advise caution in the use of the same measurement instruments. Furthermore the instruments validated in Spain have been developed with very specific or small samples. The aim of this instrumental study was to develop a new general purpose Social Support Questionnaire that overcomes these limitations. Method: With a sample of 1080 participants (48.2% women, mean age 33.51), an exploratory and confirmatory factor analysis was conducted, examining its internal consistency, reliability, convergent validity, content validity and readability. Results: A three-factor structure (Friends, Family and Significant Others Support) was replicated and confirmed (with a very good fit), explaining nearly 73% of the variance with an excellent internal consistency (.94 or more) with significant evidence of convergent validity with other related measurements of Social Support and Health. Conclusions: The parameters of structural validity, internal consistency, reliability and convergent validity, taken together, present an optimized profile when compared to the rest of the reviewed surveys.El Apoyo Social es uno de los factores determinantes del nivel de salud mejor documentados. Las diferencias culturales y en el uso de la lengua entre España y otros países de habla española aconsejan prudencia en el empleo de los mismos instrumentos de medida. Además, los instrumentos validados en España se han basado en muestras muy específicas y pequeñas. El objetivo de este estudio ha sido el desarrollo de un cuestionario de Apoyo Social para propósitos generales que supere esas limitaciones. Método: se llevaron a cabo análisis factoriales exploratorio y confirmatorio, así como un estudio de la consistencia interna, la fiabilidad, validez convergente, validez de contenido y legibilidad en una muestra de 1080 participantes (48.2% mujeres, edad media 33.51). Resultados: hallamos, replicamos y confirmamos (con muy buen ajuste) una estructura de tres factores (Apoyo de Amigos, Familia y Personas Relevantes) que explican una varianza cercana al 73%, con una excelente consistencia interna (.94 o más) y fiabilidad, y con indicios significativos de validez convergente con otras medidas de Apoyo Social y de salud relacionadas. Conclusiones: los parámetros de validez estructural, consistencia interna, fiabilidad y validez convergente tomados en su conjunto, presentan un perfil optimizado en comparación con el resto de los cuestionarios revisados

Empty Coruña? Un dispositivo académico transdisciplinar sobre a problemática urbana. Como explicar os fallos de mercado e a intervención pública no sector da vivenda?

[Resumo] O curso de verán Empty Coruña contou con diferentes tipos de actividades nas que se aplicaron diversas metodoloxías. Isto foi posible grazas á labor desenvolvida por un equipo de traballo formado por docentes de Arquitectura, Arquitectura Técnica, Socioloxía, Dereito, Economía e Empresa da UDC. Un tipo de actividade foi impartir unha clase na rúa a través da utilización dun póster contando con profesores, empresarios, membros de movementos sociais e estudantes. Expoñer contidos sobre os fallos do mercado existentes no mercado da vivenda e a teoría da intervención pública ao alumnado serviu, por un lado, para repensar os esquemas tradicionais docentes. Desta forma, a universidade acercouse á cidade como axente analizador do proceso actual que sofre e os espazos urbanos ao aire libre transformáronse en actores pasivos do curso, ao cambiar o contexto da aula. E, por outro lado, a exposición de coñecementos serviu de base para o traballo práctico e participativo que posteriormente elaborou o alumnado. Esta metodoloxía permite xerar unha retroalimentación máis efectiva que coas exposicións orais tradicionais e supón unha maior implicación do alumnado no proceso de ensinanzaaprendizaxe a partir da cesión da responsabilidade da aprendizaxe ao propio alumnado. O resultado pedagóxico foi positivo, xa que o póster facilitou a explicación dos conceptos nun breve espazo de tempo a un público sen coñecementos previos de Economía e dun xeito visual e ameno[Abstract] The summer course ‘Empty Coruña’ had different types of activities in which different methodologies have been applied. This has been possible due to the work developed by a team of professors from Architecture, Technical Architecture, Sociology, Law, Economics and Business of the UDC. One type of activity was to teach a class on the street using a poster with the participation of professors, business people, members of social movements and students. Exposing content on the existing market failures in the housing market and the theory of public intervention for students served, on the one hand, to rethink the traditional teaching schemes. In this sense, the university approached the city as an analyser agent of the current process that suffers. Outdoor urban spaces have transformed into passive actors of the course, changing the context of the classroom. On the other hand, the presentation of knowledge served as a basis for the practical and participatory work done later by the students. This methodology allows creating a more effective feedback than traditional oral presentations and involves a greater implication of the students in the teaching-learning process, transferring the responsibility to the students. The pedagogical result was positive, as the poster facilitated the explanation of the concepts in a short space of time, to a public without previous knowledge of Economy and in a visual and entertaining way