L'enigma de l'escriptura

L'enigma de l'escriptura fa un recorregut històric i pràctic pels diferents processos de la creació de l'escriptura, des dels ideogrames als fonemes i les emoticones, a través d'èpoques i cultures.This book shows the historic process of creation of scripture through different cultures and periods, from ideograms to phonemes and emoticons.El document forma part dels materials docents programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València

E=mc2, la ecuación más famosa de la física: una incomprendida

Si alguien se toma la molestia de estudiar qué ecuaciones han aparecido más a menudo en la prensa -tanto en las revistas de divulgación cientí-fica o de información general como en los diarios-no hay duda que encontrará, como ha señalado Resnick ( 1980) que la ecuación más conocida de la Física es la famosa E=mc2. En efecto, tanto si se habla del peligro nuclear como de la ciencia contemporánea o del mismo futuro de la humanidad, es bastante probable que se haga referencia a esta ecuación. Este esfuerzo de difusión, obviamente, parece legítimo y no tendría por qué preocuparnos, si no fuese porque la interpretación que a menudo se le da es totalmente incorrecta, deformando la imagen actual del comportamiento de la materia, que la ciencia ha ido construyendo a lo largo de su historia

Effect of Sporosarcina Pasteurii on the strength properties of compressed earth specimens

Microbial biodeposition of calcite induction for improving the performance of rammed earth is a research area that must be analysed in a representative environment. This analysis must consider the compaction force, particle size distribution and curing process as production variables. This paper investigates the effects of adding specific bacteria, Sporosarcina Pasteurii, into compressed earth cubes and the effect of production variables. Uniaxial compressive tests and direct shear tests have been conducted for 80 specimens. The results indicate that calcite precipitation interacts with the drying process of clay/silt resulting in reducing the compressive strength, the apparent cohesion and the friction angle. Finally, bacterial activity, which is more likely in samples cured in a high humidity environment, tends to reduce the dilatancy effect.Peer ReviewedPostprint (published version

Causas de las desigualdades territoriales de la fecundidad: un estudio a escala metropolitana en el área barcelonesa

Los comportamientos demográficos están experimentando una creciente segmentación en el interior de las regiones metropolitanas. Por ejemplo, los municipios de la Región Metropolitana de Barcelona (RMB) presentan diferentes intensidades de fecundidad, valores que incluso difieren en mayor grado que entre las provincias españolas. La principal hipótesis de este trabajo es que dichas diferencias se sustentan en la migración interna de parejas jóvenes ligadas al ciclo de vida, aunque la presencia de población extranjera o la renta media de los municipios también podrían influir. Para verificar estas hipótesis se ha calculado los índices sintéticos de fecundidad de 26 sub-áreas de la RMB, complementándose este análisis descriptivo con modelos de regresión lineal para los años 2001 y 2009. Los resultados confirman parcialmente la hipótesis principal, aunque en 2009 la complejidad residencial producto de la inmigración internacional añade la presencia de extranjeros (africanos especialmente) como factor explicativo de los altos niveles de fecundidad

New Spatial Mobility Patterns in Large Spanish Cities: from the Economic Boom to the Great Recession

Until 2008 the beginning of the economic crisis Spanish metropolitan areas were characterised by relatively high residential mobility, suburbanisation, and urban sprawl. Municipalities situated farthest away from the core cities were the areas that were expanding more rapidly, while urban cores were losing native population that was being replaced by foreign immigrants. All these features presumably changed when the Great Recession hit the Spanish economy and the housing bubble burst. Using two INE (Spanish National Statistical Institute) data sources, the Padrón, or local register, and the Estadística de Variaciones Residenciales, or residential moves statistics, this paper studies changing trends in residential mobility and migration between 1999 and 2012 in Spain, focusing on the country's main urban areas: Madrid, Barcelona, Valencia, and Seville. In particular, internal migration patterns during the economic expansion and crisis periods are compared. Despite the fact that high unemployment since 2008 has certainly affected pre-crisis trends, results show that residential mobility has decreased much less than expected. Nevertheless, territorial patterns have changed and are now much less polarised. Urban cores and inner-ring towns, which had previously been losing inhabitants because of people moving to outer-ring areas, are now losing less native population. By contrast, suburban municipalities, which had been the most attractive to internal migrants during the economic growth period, are now much less appealing, as corroborated by the fact that practically no new housing is being built in these areas and their housing market has plummeted

Denitrification of groundwater with pyrite and Thiobacillus denitrificans

Anaerobic batch and flow-through experiments were performed to confirm the role of pyrite as electron donor in bacterial denitrification and to look into the feasibility of pyrite-driven denitrification of nitrate- contaminated groundwater. Nitrate reduction was satisfactorily accomplished in experiments with pyrite as the sole electron donor, in presence of the autotrophic denitrifying bacterium Thiobacillus denitrificans and at nitrate concentrations comparable to those observed in contaminated groundwater. The experimental results corroborated field studies in which the reaction occurred in aquifers. Nitrate reduction rates and nitrate removal efficiencies were dependent on pyrite grain size, initial nitrate concentration, nitrate-loading rate and pH. The N and O isotopic enrichment factors (εN and εO) obtained experimentally for pyrite-driven nitrate reduction by T. denitrificans ranged from − 13.5¿ to − 15.0¿ and from − 19.0¿ to − 22.9¿, respectively. These values indicated the magnitude of the isotope fractionation that occurs in nitrate- contaminated aquifers dominated by autotrophic denitrification

Tierra y Cielos ¿Dos universos separados?

El estudio de la gravitación constituye una ocasión excepcional para mostrar la ciencia y la tecnología en toda su riqueza y complejidad, considerando, entre otros aspectos: ¿ Las situaciones problemáticas relevantes que llevaron a la construcción de los conocimientos, ¿ las dificultades de todo tipo con las que hubo que enfrentarse y, muy en particular, ¿ la necesidad de superar las 'evidencias de sentido común' que establecían una supuesta barrera infranqueable entre la Tierra y los Cielos y que obstaculizaron durante siglos el desarrollo científico. En este trabajo presentamos un programa de actividades para el estudio de la gravitación en la secundaria superior, orientado a favorecer la participación de los estudiantes, en alguna medida, en la reconstrucción de este proceso que constituyó la denominada primera gran revolución científica y asomándonos al estudio de una de las ciencias más antiguas, la Astronomía, que hoy sigue despertando gran interés

Engineering Pseudomonas putida for isoprenoid production by manipulating endogenous and shunt pathways supplying precursors

Background: The soil bacterium Pseudomonas putida is a promising platform for the production of industrially valuable natural compounds. In the case of isoprenoids, the availability of biosynthetic precursors is a major limiting factor. In P. putida and most other bacteria, these precursors are produced from pyruvate and glyceraldehyde 3-phosphate by the methylerythritol 4-phosphate (MEP) pathway, whereas other bacteria synthesize the same precursors from acetyl-CoA using the unrelated mevalonate (MVA) pathway. Results: Here we explored different strategies to increase the supply of isoprenoid precursors in P. putida cells using lycopene as a read-out. Because we were not aiming at producing high isoprenoid titers but were primarily interested in finding ways to enhance the metabolic flux to isoprenoids, we engineered the well-characterized P. putida strain KT2440 to produce low but detectable levels of lycopene under conditions in which MEP pathway steps were not saturated. Then, we compared lycopene production in cells expressing the Myxococcus xanthus MVA pathway genes or endogenous MEP pathway genes (dxs, dxr, idi) under the control of IPTG-induced and stress-regulated promoters. We also tested a shunt pathway producing isoprenoid precursors from ribulose 5-phosphate using a mutant version of the Escherichia coli ribB gene. Conclusions: The most successful combination led to a 50-fold increase in lycopene levels, indicating that P. putida can be successfully engineered to substantially increase the supply of metabolic substrates for the production of industrially valuable isoprenoids

Self-assessment exercises in continuum mechanics with autonomous learning

Peer Reviewe

Self-assessment exercises in continuum mechanics with autonomous learning

Peer ReviewedPostprint (published version