On relative normal modes

We generalize the Weinstein-Moser theorem on the existence of nonlinear normal modes near an equilibrium in a Hamiltonian system to a theorem on the existence of relative perodic orbits near a relative equilibrium in a Hamiltonian system with continuous symmetries. In particular we prove that under appropriate hypotheses there exist relative periodic orbits near relative equilibria even when these relative equilibria are singular points of the corresponding moment map, i.e. when the reduced spaces are singular.Comment: 5 pages, to appear in C.R. Acad. Sci. Paris, t. 328, S'erie I, 199

The (wrong) lenguaje of the caricature: the truth in time of crisis

Ortego publica en 1869 una serie de álbumes, Menestra, en los que hace alarde de una multiplicidad de recursos gráficos e iconográficos, jugando con el idioma, las referencias a la pintura o a la obra grabada y dibujada de Goya, para difundir su convicción democrática y republicana. Partiendo del motivo de la “sombra”, analizamos los procedimientos utilizados en las litografías relacionándolos con los contextos político, estético y cultural.In 1869, Ortego published a series of Menestra albums in which he made prominent use of multiple graphic and iconographic processes, playing with the language, with references to paintings and to Goya’s engravings and drawings, with the aim of disseminating his democratic and republican beliefs. Starting from the “shadow” motif, we shall analyse the processes used in the lithographies and relate them to the political, aesthetic and cultural contexts

A Fundamental Theorem for Hypersurfaces in Semi-Riemannian Warped Products

We give necessary and sufficient conditions for a semi-Riemannian manifold of arbi- trary signature to be locally isometrically immersed into a warped product ±I ×a M^n (c), where I ⊂ R and M^n (c) is a semi-Riemannian space of constant nonzero sectional cur- vature. Then, we describe a way to use the structure equations of such immersions to construct foliations of marginally trapped surfaces in a four-dimensional Lorentzian space- times. We point out that, sometimes, Gauß and Codazzi equations are not sufficient to ensure the existence of a local isometric immersion of a semi-Riemannian manifold as a hypersurface of another manifold. We finally give two low-dimensional examples to illustrate our results.Spanish MEC-FEDER Grant MTM2007-60731 and Junta de Andalucía Grant P09-FQM-4496 (with FEDER funds.

Virulence- and signaling-associated genes display a preference for long 3′UTRs during rice infection and metabolic stress in the rice blast fungus

Generation of mRNA isoforms by alternative polyadenylation (APA) and their involvement in regulation of fungal cellular processes, including virulence, remains elusive. Here, we investigated genome‐wide polyadenylation site (PAS) selection in the rice blast fungus to understand how APA regulates pathogenicity. More than half of Magnaporthe oryzae transcripts undergo APA and show novel motifs in their PAS region. Transcripts with shorter 3′UTRs are more stable and abundant in polysomal fractions, suggesting they are being translated more efficiently. Importantly, rice colonization increases the use of distal PASs of pathogenicity genes, especially those participating in signalling pathways like 14‐3‐3B, whose long 3′UTR is required for infection. Cleavage factor I (CFI) Rbp35 regulates expression and distal PAS selection of virulence and signalling‐associated genes, tRNAs and transposable elements, pointing its potential to drive genomic rearrangements and pathogen evolution. We propose a noncanonical PAS selection mechanism for Rbp35 that recognizes UGUAH, unlike humans, without CFI25. Our results showed that APA controls turnover and translation of transcripts involved in fungal growth and environmental adaptation. Furthermore, these data provide useful information for enhancing genome annotations and for cross‐species comparisons of PASs and PAS usage within the fungal kingdom and the tree of life

Unsupervised Multiple Domain Translation through Controlled Disentanglement in Variational Autoencoder

Unsupervised Multiple Domain Translation is the task of transforming data from one domain to other domains without having paired data to train the systems. Typically, methods based on Generative Adversarial Networks (GANs) are used to address this task. However, our proposal exclusively relies on a modified version of a Variational Autoencoder. This modification consists of the use of two latent variables disentangled in a controlled way by design. One of this latent variables is imposed to depend exclusively on the domain, while the other one must depend on the rest of the variability factors of the data. Additionally, the conditions imposed over the domain latent variable allow for better control and understanding of the latent space. We empirically demonstrate that our approach works on different vision datasets improving the performance of other well known methods. Finally, we prove that, indeed, one of the latent variables stores all the information related to the domain and the other one hardly contains any domain information

Evolución del fitoplancton en el Parque Nacional de las Tablas de Daimiel (Ciudad Real, 1996-2002)

El Parque Nacional de Las Tablas de Daimiel (PNTD) es un humedal semiárido situado en la Llanura Manchega (Ciudad Real). En este artículo se expone la dinámica del fitoplancton desde 1996 hasta 2002, examinando las continuidades y divergencias que se observan en el espacio y el tiempo. Tres puntos del humedal (PG: entrada al Parque; MM y PN: salida en zona media y final) se muestrearon mensualmente desde Marzo 1996 a Diciembre 2002. El biovolumen total del fitoplancton del PNTD fue muy variable tanto en el tiempo como en el espacio, el valor mínimo y el máximo se presentaron en PG (0.06 mm3/l en mayo de 1996, y 775 mm3/l en septiembre de 2001). Se observa un marcado incremento del promedio de biovolumen de todo el humedal a lo largo del tiempo, de 11 ± 3 mm3/l en 1996 a 40 ± 9 mm3/l en 2002. La contribución relativa de los grupos taxonómicos al biovolumen total de fitoplancton mostró también cambios a corto y largo plazo, y fueron distintos en cada una de las tablas muestreadas. Hemos encontrado algunas especies de algas que son indicadoras de cierto grado de salinidad en el agua, ellas son: Chaetoceros muelleri, Urosolenia sp. y Katodinium fungiforme. Así como un aumento en el número de especies y densidad de las euglenofitas. Esta larga serie de datos nos permite extraer una serie de conclusiones sobre el funcionamiento de los productores primarios planctónicos en un humedal somero: a) a la escala espacial de todo el humedal el biovolumen de fitoplancton responde al clima local; b) la tendencia de eutrofización es claramente detectada en todo el humedal; c) las fluctuaciones hidrológicas provocan variaciones a corto plazo, permitiendo una serie continua de estados alternantes y no cíclicos de la comunidad; d) la heterogeneidad espacial de este sistema de islas y tablazos permite una amplia riqueza en el conjunto del humedal.Las Tablas de Daimiel National Park (TDNP) is a wetland located in La Mancha Plain (Ciudad Real, Central Spain). Our study reports 1996-2002 phytoplankton dynamics, examining spatio-temporal patterns of continuity and divergence. Three wetland sites (PG-main inlet, MM and PN-main outlets) were sampled monthly from March 1996 to December, 2002. Overall phytoplankton biovolume were very variable in space and time. Extreme values occurred in PG in May, 1996 (0.06 mm3/l) and September, 2001 (775 mm3/l). Average values of phytoplankton biovolume experienced aa marked increment over timefrom 11±3 mm3/l in 1996 () to 40±9 mm3/l in 2002. The relative contribution to the total biovolume of the taxonomic groups also showed short and long-term changes and they were different in each of the sampled sites. Some species indicating increasing salinity, such as Chaetoceros muelleri, Urosolenia sp. and Katodinium fungiforme, were recorded. Species numbers and density of euglenoids increased as well. This long-term dataset enabled us to draw some conclusions over planktonic primary producers functioning in a shallow wetland: a) at the wetland scale phytoplankton biovolum responds to local climate, b) a eutrophication trend is clearly detected in the whole wetland, c) hydrologic fluctuations are responsible for a short-term variability, thus allowing a variety of non-cyclic assemblage' s alternate states, d) spatial heterogeneity arising from the distribution of water tables and islands results in a remarkable species richness at the wetland scale

Formas de rasgar la racionalidad o la escritura intranquila de Menchu Gutiérrez

The writings of Menchu Gutiérrez carry us through an intense and vibrand present. A present as far from the anecdote as the own course of constellations which turn each sequence in an Epiphany “fact”. The present immediately brings us inside a highly symbolic space weaved by the writer, and involves us in a series of never exact speculative reduplications through which we once again pass through the rooms of any interior castle as well as through the perfumed and beautifully illuminated stations of a new manuscript of “rich hours”. Writings at the edge, in the mountain range that gathers prose and poetry, understanding and enigma, reason and unreason through which we intend to stroll listening with attention to this unheard of language, testing radiant darknesses with hands offered by the texts.Los relatos escritos por Menchu Gutiérrez nos someten a un presente vibrante e intenso, un presente, tan alejado de la anécdota como el propio curso de las constelaciones, que convierte cada secuencia en «hecho», en una epifanía. El presente nos adentra de inmediato en el espacio altamente simbólico tejido por la escritora y nos involucra en una serie de reduplicaciones especulares nunca exactas, mediante las cuales volvemos a recorrer tanto las moradas de algún castillo interior como las estaciones perfumadas preciosamente iluminadas de un nuevo manuscrito de las «ricas horas». Escritura al filo, en la cordillera, en que se reúnen prosa y poesía, comprensión y enigma, razón y sinrazón y por la que nos proponemos pasear, oído atento a esta lengua inaudita, tanteando oscuridades radiantes con las manos ofrecidas por los propios textos