Tratamiento numérico de materiales compuestos mediante la teoría de homogeneización

El presente trabajo se emmarca dentro de las teorías y métodos que hacen posible la representación por ordenador de los materiales compuesto. Como se sabe, la búsqueda de leyes matemáticas que determinan el comportamiento de esta clase de materiales ha sido objeto de estudio durante varias décadas. Pero, su elavada dificultad conduce a elaborar complejas teorías; o por el contrario, se utlizan grandes simplificaciones cuyo resultado genera modelos poco acertados.Postprint (published version

X-ray flares from propagation instabilities in long Gamma-Ray Burst jets

We present a numerical simulation of a gamma-ray burst jet from a long-lasting engine in the core of a 16 solar mass Wolf-Rayet star. The engine is kept active for 6000 s with a luminosity that decays in time as a power-law with index -5/3. Even though there is no short time-scale variability in the injected engine luminosity, we find that the jet's kinetic luminosity outside the progenitor star is characterized by fluctuations with relatively short time scale. We analyze the temporal characteristics of those fluctuations and we find that they are consistent with the properties of observed flares in X-ray afterglows. The peak to continuum flux ratio of the flares in the simulation is consistent with some, but not all, the observed flares. We propose that propagation instabilities, rather than variability in the engine luminosity, are responsible for the X-ray flares with moderate contrast. Strong flares such as the one detected in GRB 050502B, instead, cannot be reproduced by this model and require strong variability in the engine activity.Comment: 6 pages, MNRAS in pres

Water Availability Is the Main Climate Driver of Neotropical Tree Growth

• Climate models for the coming century predict rainfall reduction in the Amazonian region, including change in water availability for tropical rainforests. Here, we test the extent to which climate variables related to water regime, temperature and irradiance shape the growth trajectories of neotropical trees. • We developed a diameter growth model explicitly designed to work with asynchronous climate and growth data. Growth trajectories of 205 individual trees from 54 neotropical species censused every 2 months over a 4-year period were used to rank 9 climate variables and find the best predictive model. • About 9% of the individual variation in tree growth was imputable to the seasonal variation of climate. Relative extractable water was the main predictor and alone explained more than 60% of the climate effect on tree growth, i.e. 5.4% of the individual variation in tree growth. Furthermore, the global annual tree growth was more dependent on the diameter increment at the onset of the rain season than on the duration of dry season. • The best predictive model included 3 climate variables: relative extractable water, minimum temperature and irradiance. The root mean squared error of prediction (0.035 mm.d–1) was slightly above the mean value of the growth (0.026 mm.d–1). • Amongst climate variables, we highlight the predominant role of water availability in determining seasonal variation in tree growth of neotropical forest trees and the need to include these relationships in forest simulators to test, in silico, the impact of different climate scenarios on the future dynamics of the rainforest

Source water, phenology and growth of two tropical dry forest tree species growing on shallow karst soils

Seasonally dry tropical forests are dominated by deciduous and evergreen tree species with a wide range of leaf phenology. We hypothesized that Piscidia piscipula is able to extend leaf senescence until later in the dry season due to deeper and more reliable water sources than Gymnopodium floribundum, which loses leaves earlier in the dry season. Physiological performance was assessed as timing of leaf production and loss, growth, leaf water potential, depth of water uptake determined by stable isotopes, and leaf stable isotopic composition of carbon (δ¹³C) and oxygen (δ¹⁸O). P. piscipula took water primarily from shallow sources, whereas G. floribundum took water from shallow and deep sources. The greatest variation in water sources occurred during the onset of the dry season, when G. floribundum was shedding old leaves and growing new leaves, but P. piscipula maintained its leaves from the previous wet season. P. piscipula showed greater relative growth rate, greater leaf expansion rates, and more negative predawn and midday water potentials than G. floribundum. P. piscipula also exhibited greater leaf organic δ¹³C and lower δ¹⁸O values, indicating that the decrease in photosynthetic carbon isotope discrimination was associated with greater stomatal conductance and greater photosynthesis. Our results indicate that the contrasting early and late dry season leaf loss phenology of these two species is not simply determined by rooting depth, but rather a more complicated suite of characteristics based on opportunistic use of dynamic water sources, maximizing carbon gain, and maintenance of water potential during the dry season

SUMOylation controls Hu antigen R posttranscriptional activity in liver cancer

© 2024 The Author(s). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).The posttranslational modification of proteins critically influences many biological processes and is a key mechanism that regulates the function of the RNA-binding protein Hu antigen R (HuR), a hub in liver cancer. Here, we show that HuR is SUMOylated in the tumor sections of patients with hepatocellular carcinoma in contrast to the surrounding tissue, as well as in human cell line and mouse models of the disease. SUMOylation of HuR promotes major cancer hallmarks, namely proliferation and invasion, whereas the absence of HuR SUMOylation results in a senescent phenotype with dysfunctional mitochondria and endoplasmic reticulum. Mechanistically, SUMOylation induces a structural rearrangement of the RNA recognition motifs that modulates HuR binding affinity to its target RNAs, further modifying the transcriptomic profile toward hepatic tumor progression. Overall, SUMOylation constitutes a mechanism of HuR regulation that could be potentially exploited as a therapeutic strategy for liver cancer.This work was supported by grants to M.L.M.-C. from Departamento de Industria del Gobierno Vasco, Spain; Ministerio de Ciencia e Innovación, Spain (grant no. PID2020-117116RB-I00); European Regional Development Fund (ERDF), EU; and CIBERehd, which is funded by Instituto de Salud Carlos III (ISCIII), Spain. M.L.M.-C. and J.S. received funding from Ministerio de Ciencia e Innovación (grant no. RTC2019-007125-1) and ISCIII (grant no. DTS20/00138). M.L.M.-C. and R.M.L. acknowledge Ministerio de Ciencia e Innovación (grant no. RED2022-134397-T). M.L.M.-C. and J.M.B. were awarded with a grant from Fundación la Caixa, Spain (grant no. HR17-00601). M.L.M.-C., J.M.B., M.A.A., and J.J.G.M. acknowledge financial support from Fundación Científica de la Asociación Española Contra el Cáncer (AECC), Spain. M.S.R. recognizes funding from Fondo Sectorial de Investigación SRE - CONACYT, Mexico (grant no. 0280365); Horizon 2020 Research and Innovation Program funded under Marie Skłodowska-Curie Actions, EU (grant no. 765445); and REPÈRE and Programme de Prématuration from Région Occitanie, France. M.G., S.D., and K.M.-M. were supported by the National Institute on Aging (NIA), National Institutes of Health (NIH), US (grant no. Z01-AG000511-23). I.D.-M. is grateful for the grants received from Junta de Andalucía, Spain (grant no. BIO-198, US-1254317, P18-FR-3487, and P18-HO-4091); Ministerio de Ciencia, Innovación y Universidades, Spain (grant no. PGC2018-096049-BI00); and Fundación Ramón Areces, Spain. T.D. acknowledges Fondation ARC, France (grant no. 208084). J.J.G.M. was supported by Junta de Castilla y León, Spain (grant no. SA063P17); Fundación La Marató TV3, Spain (grant no. 201916-31); ISCIII (grant no. PI19/00819); CIBERehd; and ERDF (grant no. OLD-HEPAMARKER). M.A.A. recognizes Gobierno de Navarra, Spain (grant no. GºNa 42/21); Eurorregión Nueva Aquitania-Euskadi-Navarra, Spain; Ministerio de Ciencia e Innovación (grant no. PID2019-104878RB-I00); and CIBERehd. A.P. expresses gratitude to the European Research Council (ERC), EU (grant no. 804236) for their support. M.D.G. received financial support from Junta de Andalucía (grant no. PEMP-0036-2020 and BIO-0139); Ministerio de Universidades, Spain (grant no. FPU20/03957); ISCIII (grant no. PI20/01301), Fundación Sociedad Española de Endocrinología y Nutrición (FSEEN), Spain; CIBERehd; and CIBERobn, which is also funded by ISCIII. J.M.B. acknowledges Euskadi RIS3 (grant no. 2019222054, 2020333010, and 2021333003) and Elkartek programs from Gobierno Vasco (grant no. KK-2020/00008); ISCIII (grant no. PI18/01075, CPII19/00008, and PI21/00922); CIBERehd; PSC Support, UK; AMMF The Cholangiocarcinoma Charity, UK (grant no. EU/2019/AMMFt/001); Horizon 2020 Research and Innovation Program (grant no. 825510); ERDF; and PSC Partners Seeking a Cure, US. A.L. received financial support from the Damon Runyon-Rachleff Innovation Award, US (grant no. DR52-18) and the MERIT Award (R37) from the National Cancer Institute (NCI), NIH (grant no. R37CA230636). F.E. expresses his gratitude to ProteoRed from ISCIII (grant no. PT13/0001/0027) and CIBERehd. N.G.A.A. was funded by Ministerio de Ciencia, Innovación y Universidades (grant no. RTI2018-095700-B-I00). R.B. acknowledges financial support from Gobierno Vasco (grant no. IT1165-19); Ministerio de Economía, Industria y Competitividad, Spain (grant no. SAF2017-90900-REDT); Ministerio de Economía, Industria y Competitividad, ERDF (grant no. BFU2017-84653-P); Ministerio de Ciencia e Innovación (grant no. PID2020-114178GB-I00); and Horizon 2020 funded under Marie Skłodowska-Curie Actions (grant no. 765445-EU). A.M.A. acknowledges CIBERehd. L.A.M.-C. obtained grants from Ministerio de Economía y Competitividad (grant no. CSD2008-00005); Ministerio de Economía, Industria y Competitividad (grant no. BFU2016-77408-R); ISCIII; and EJP RD, EU (grant no. EJPRD19-040). I.G.-R. was supported by Ministerio de Economía, Industria y Competitividad (grant no. BES-2017-080435 ). M.S.-M. is grateful to the AECC, Sede de Bizkaia, Spain for the financial support. J.D.Z. was awarded with a grant from Ministerio de Economía, Industria y Competitividad (grant no. SEV-2016-0644-18-2). C.M. acknowledges Gobierno Vasco (grant no. IT-1264-19) and Ministerio de Ciencia e Innovación (grant no. PID2022-136788OB-I00). A.V.-C. was supported by Ministerio de Educación, Cultura y Deporte, Spain (grant no. FPU016/01513). C.F.-R. thanks Tekniker, Spain and CIC bioGUNE, Spain for financial support. A.G.-d.R. was funded by Bikaintek program from Gobierno Vasco (grant no. 48-AF-W1-2019-00012). N.G.-U. obtained a grant from Gobierno Vasco. T.C.D. expresses gratitude to AECC. J.S. received financial support from CIBERehd. C.M.R.-G. was supported by Ayudas a la Recualificación Margarita Salas from Universidad de Extremadura, Ministerio de Universidades financed by NextGenerationEU.Peer reviewe

Termite sensitivity to temperature affects global wood decay rates.

Deadwood is a large global carbon store with its store size partially determined by biotic decay. Microbial wood decay rates are known to respond to changing temperature and precipitation. Termites are also important decomposers in the tropics but are less well studied. An understanding of their climate sensitivities is needed to estimate climate change effects on wood carbon pools. Using data from 133 sites spanning six continents, we found that termite wood discovery and consumption were highly sensitive to temperature (with decay increasing >6.8 times per 10°C increase in temperature)-even more so than microbes. Termite decay effects were greatest in tropical seasonal forests, tropical savannas, and subtropical deserts. With tropicalization (i.e., warming shifts to tropical climates), termite wood decay will likely increase as termites access more of Earth's surface

What is in a name? That which we call cecropia peltata by any other name would be as invasive?

The recent opinion piece by Sheil and Padmanaba (2011) argues that greater attention is required for invasive species management procedures that are relevant to and realistic for developing countries. They use the example of the Neotropical tree Cecropia as an introduction toWest Java to illustrate their point. In our invited response we contend that the assumptions and data on the dynamics of Cecropia in Java presented in their paper, as well as their review of global Cecropia introductions, are of reduced scientific value. Even so, we agree with the paper’s opinion that the naturalised species of Cecropia in West Java represent a considerable invasion risk and that funding must be improved so that the capacity for invasion ecology research and management of invasive alien species in developing countries is more effective. Unlike Sheil and Padmanaba (2011), however, we conclude that there is already enough evidence to be concerned by the threat of Cecropia to natural ecosystems, but that knowledge of the relevant taxa is currently insufficient to recommend the most appropriate control options not only for Java, but also for other Cecropia introductions elsewhere in the world. © 2011 Botanical Society of Scotland and Taylor & Francis