Characterizing and following eddies in Drake Passage

Drake Passage, the gap between South America and Antarctica, is a very energetic region, with strong currents and numerous eddies. These eddies are important for mixing waters across the main three fronts, and for affecting the biological productivity in the region. We use weekly maps of colour images, sea level anomaly and geostrophic velocities to characterize physical and biological activity in the region surrounding Drake Passage. In particular, we note that the largest eddy kinetic energy occurs to the east of the passage and is principally in the area bounded by the mean Subantarctic Front (SAF) and the mean Polar Front, whilst the biological productivity is highest in coastal regions, with the SAF acting as a clear southern boundary. In a number of cases, cyclonic eddies detected by altimetry also show a strong signature in ocean color. Regular XBT (eXpendable BathyThermograph) surveys provide information on sub-surface structure, confirming the altimetric identification of features and showing that they often contain water masses originating from the other side of the front

Timing the formation and assembly of early-type galaxies via spatially resolved stellar populations analysis

To investigate star formation and assembly processes of massive galaxies, we present here a spatially-resolved stellar populations analysis of a sample of 45 elliptical galaxies (Es) selected from the CALIFA survey. We find rather flat age and [Mg/Fe] radial gradients, weakly dependent on the effective velocity dispersion of the galaxy within half-light radius. However, our analysis shows that metallicity gradients become steeper with increasing galaxy velocity dispersion. In addition, we have homogeneously compared the stellar populations gradients of our sample of Es to a sample of nearby relic galaxies, i.e., local remnants of the high-z population of red nuggets. This comparison indicates that, first, the cores of present-day massive galaxies were likely formed in gas-rich, rapid star formation events at high redshift (z>2). This led to radial metallicity variations steeper than observed in the local Universe, and positive [Mg/Fe] gradients. Second, our analysis also suggests that a later sequence of minor dry mergers, populating the outskirts of early-type galaxies (ETGs), flattened the pristine [Mg/Fe] and metallicity gradients. Finally, we find a tight age-[Mg/Fe] relation, supporting that the duration of the star formation is the main driver of the [Mg/Fe] enhancement in massive ETGs. However, the star formation time-scale alone is not able to fully explain our [Mg/Fe] measurements. Interestingly, our results match the expected effect that a variable stellar initial mass function would have on the [Mg/Fe] ratio.Comment: Accepted for publication in MNRA

Un algorisme evolutiu multiagent per a problemes d’optimització combinatòria

Diversos problemes en telecomunicacions són de naturalesa combinatòria i la seva resolució òptima és en molts casos impossible, ja que el temps de resolució mitjançant algorismes convencionals creix exponencialment amb la mida del problema. Llavors, certs algorismes de naturalesa probabilística com el simulated annealing, algorismes genètics, mètodes multiagent etc. - suggerits per processos naturals evolutius o pel comportament social d'insectes- resulten útils per trobar solucions pròximes a l'òptima en un temps raonable. En aquest TFC s’ha implementat un nou mètode d’optimització (que hem aplicat a l’acoloriment de grafs, base de l’assignació de freqüències GSM) i que s’inspira en el comportament social d’uns insectes socials peculiars: els borinots. Cada borinot porta codificada una solució al problema d’acoloriment., que evoluciona a mesura que els insectes virtuals segueixen el seu cicle vital (busquen i troben aliment, pateixen mutacions, etc.). D’aquesta manera, i en un procés que simula l’evolució darwinista, s’arriba a trobar solucions bones del problema. L’eficiència d’aquest mètode s’ha comprovat mitjançant un estudi d’acoloriment en grafs aleatoris i s’ha comparat respecte altres mètodes d’optimització com el d’àngels i mortals i un algorisme genètic, arribant a la conclusió que es tracta d’un mètode vàlid per la resolució

Un algorisme evolutiu multiagent per a problemes d’optimització combinatòria

Diversos problemes en telecomunicacions són de naturalesa combinatòria i la seva resolució òptima és en molts casos impossible, ja que el temps de resolució mitjançant algorismes convencionals creix exponencialment amb la mida del problema. Llavors, certs algorismes de naturalesa probabilística com el simulated annealing, algorismes genètics, mètodes multiagent etc. - suggerits per processos naturals evolutius o pel comportament social d'insectes- resulten útils per trobar solucions pròximes a l'òptima en un temps raonable. En aquest TFC s’ha implementat un nou mètode d’optimització (que hem aplicat a l’acoloriment de grafs, base de l’assignació de freqüències GSM) i que s’inspira en el comportament social d’uns insectes socials peculiars: els borinots. Cada borinot porta codificada una solució al problema d’acoloriment., que evoluciona a mesura que els insectes virtuals segueixen el seu cicle vital (busquen i troben aliment, pateixen mutacions, etc.). D’aquesta manera, i en un procés que simula l’evolució darwinista, s’arriba a trobar solucions bones del problema. L’eficiència d’aquest mètode s’ha comprovat mitjançant un estudi d’acoloriment en grafs aleatoris i s’ha comparat respecte altres mètodes d’optimització com el d’àngels i mortals i un algorisme genètic, arribant a la conclusió que es tracta d’un mètode vàlid per la resolució

The mitochondrial and chloroplast dual targeting of a multifunctional plant viral protein modulates chloroplast-to-nucleus communication, RNA silencing suppressor activity, encapsidation, pathogenesis and tissue tropism

[EN] Plant defense against melon necrotic spot virus (MNSV) is triggered by the viral auxiliary replicase p29 that is targeted to mitochondrial membranes causing morphological alterations, oxidative burst and necrosis. Here we show that MNSV coat protein (CP) was also targeted to mitochondria and mitochondrial-derived replication complexes [viral replication factories or complex (VRC)], in close association with p29, in addition to chloroplasts. CP import resulted in the cleavage of the R/arm domain previously implicated in genome binding during encapsidation and RNA silencing suppression (RSS). We also show that CP organelle import inhibition enhanced RSS activity, CP accumulation and VRC biogenesis but resulted in inhibition of systemic spreading, indicating that MNSV whole-plant infection requires CP organelle import. We hypothesize that to alleviate the p29 impact on host physiology, MNSV could moderate its replication and p29 accumulation by regulating CP RSS activity through organelle targeting and, consequently, eluding early-triggered antiviral response. Cellular and molecular events also suggested that S/P domains, which correspond to processed CP in chloroplast stroma or mitochondrion matrix, could mitigate host response inhibiting p29-induced necrosis. S/P deletion mainly resulted in a precarious balance between defense and counter-defense responses, generating either cytopathic alterations and MNSV cell-to-cell movement restriction or some degree of local movement. In addition, local necrosis and defense responses were dampened when RSS activity but not S/P organelle targeting was affected. Based on a robust biochemical and cellular analysis, we established that the mitochondrial and chloroplast dual targeting of MNSV CP profoundly impacts the viral infection cycle.The authors thank L. Corachan-Valencia for technical assistance. This work was funded by grant BIO2017¿88321-R from the Spanish Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER). J.A.N. and M.S.-B. are the recipients of a postdoctoral contract and a PhD fellowship from the Ministerio de Ciencia, Innovacion y Universidades of Spain, respectively. Ministerio de Ciencia e Innovacion (PID2020-115571RB-I00), European Regional Development FundNavarro Bohigues, JA.; Sáiz-Bonilla, M.; Sanchez Navarro, JA.; Pallás Benet, V. (2021). The mitochondrial and chloroplast dual targeting of a multifunctional plant viral protein modulates chloroplast-to-nucleus communication, RNA silencing suppressor activity, encapsidation, pathogenesis and tissue tropism. The Plant Journal. 108(1):197-218. https://doi.org/10.1111/tpj.15435S197218108

Skyrme N2LO pseudo-potential for calculations of properties of atomic nuclei

We present recent developments obtained in the so-called N2LO extension of the usual Skyrme pseudo-potential. In particular, we discuss the isovector splitting mass in infinite nuclear matter and the pairing gaps of selected semi-magic even-even nuclei

CO2 emissions from a spark ignition engine operatin on natural-hydrogen blends (HCNG)

The addition of hydrogen to natural gas could be a short-term alternative to today’s fossil fuels, as greenhouse gas emissions may be reduced. The aim of this study is to evaluate the emissions and performance of a spark ignition engine fuelled by pure natural gas, pure hydrogen, and different blends of hydrogen and natural gas (HCNG). Increasing the hydrogen fraction leads to variations in cylinder pressure and CO2 emissions. In this study, a combustion model based on thermodynamic equations is used, considering separate zones for burned and unburned gases. The results show that the maximum cylinder pressure rises as the fraction of hydrogen in the blend increases. The presence of hydrogen in the blend leads to a decrease in CO2 emissions. Due to the properties of hydrogen, leaner fuel–air mixtures can be used along with the appropriate spark timing, leading to an improvement in engine emissions with no loss of performance

Desarrollo de un laboratorio virtual para la medida de ciclos indicados de un motor alternativo policombustible de encendido provocado

Se ha desarrollado un laboratorio virtual para la medida de ciclos indicados en un motor alternativo policombustible de encendido provocado. El laboratorio virtual desarrollado permite por una parte simular y obtener el ciclo indicado de un motor alternativo de cuatro tiempos, pudiendo modificar los parámetros más importantes de operación (régimen de giro, presiones de admisión y escape, temperaturas, etc.) y de diseño (parámetros geométricos del motor). Por otra parte, el laboratorio virtual permite simular el ensayo del motor en banco de pruebas y la medida del ciclo indicado. Los modelos matemáticos necesarios se han escrito en lenguaje Fortran, y estos interaccionan con un interfaz gráfico de usuario (GUI) programado en VEE®. El laboratorio virtual puede implementarse en una plataforma virtual de enseñanza de manera que los alumnos puedan tener acceso al sistema desde cualquier ordenador, en cualquier momento y desde cualquier lugar