Learning to do multiframe wavefront sensing unsupervisedly: applications to blind deconvolution

Observations from ground based telescopes are affected by the presence of the Earth atmosphere, which severely perturbs them. The use of adaptive optics techniques has allowed us to partly beat this limitation. However, image selection or post-facto image reconstruction methods applied to bursts of short-exposure images are routinely needed to reach the diffraction limit. Deep learning has been recently proposed as an efficient way to accelerate these image reconstructions. Currently, these deep neural networks are trained with supervision, so that either standard deconvolution algorithms need to be applied a-priori or complex simulations of the solar magneto-convection need to be carried out to generate the training sets. Our aim here is to propose a general unsupervised training scheme that allows multiframe blind deconvolution deep learning systems to be trained simply with observations. The approach can be applied for the correction of point-like as well as extended objects. Leveraging the linear image formation theory and a probabilistic approach to the blind deconvolution problem produces a physically-motivated loss function. The optimization of this loss function allows an end-to-end training of a machine learning model composed of three neural networks. As examples, we apply this procedure to the deconvolution of stellar data from the FastCam instrument and to solar extended data from the Swedish Solar Telescope. The analysis demonstrates that the proposed neural model can be successfully trained without supervision using observations only. It provides estimations of the instantaneous wavefronts, from which a corrected image can be found using standard deconvolution technniques. The network model is roughly three orders of magnitude faster than applying standard deconvolution based on optimization and shows potential to be used on real-time at the telescope.Comment: 11 pages, 4 figures, accepted for publication in A&

Estudio fisiográfico-sedimentológico de las rías altas del Norte de Lugo

Esta breve comunicación forma parte de una investigación, cuyo conjunto es tema de la tesis doctoral de uno de nosotros (N. T. R.). Se estudian ciertos fenómenos de erosión y sedimentación que tienen lugar en estas rías del litoral cantábrico, a partir de las características morfológicas y de textura que ofrecen los materiales detríticos litorales y continentales en sus márgenes.Estos accidentes geográficos vienen sufriendo un acentuado fenómeno de relleno por materiales procedentes del mar de tipo arenoso y de tierra, de carácter térreo-fangoso ; tal proceso de relleno se ha acentuado a medida que se han desarrollado las marismas, junqueras y bajos de arena, de tal modo, que actualmente el acceso a las zonas interiores portuarias se hace con dificultad. La deposición de sedimentos es debida al desequilibrio existente entre los aportes de materiales procedentes del mar y de tierra y el poder de arrastre del juego de mareas y corrientes en el ámbito de las rías. En consecuencia, el tema es de gran interés no sólo desde el punto de vista de la investigación científica, sino también utilitario de tipo  técnico, puesto que plantea problemas relacionados con el acceso a zonas portuarias a lo largo de vías de comunicación marítima

MTBVAC, a live TB vaccine poised to initiate efficacy trials 100 years after BCG

At its 100th birthday of its first administration to a newborn, BCG has been (and continues being) an inspiration for the construction and development of hundreds of new TB vaccine candidates in the last two and a half decades. Today, 14 candidates are in clinical development inside the global TB vaccine pipeline. MTBVAC is one of these candidates. Based on a live-attenuated Mycobacterium tuberculosis clinical isolate, MTBVAC''s 25 years of vaccine discovery, construction and characterisation have followed Pasteur principles, and in the process, BCG has served as a reference gold standard for establishing the safety and protective efficacy of new TB vaccine candidates. MTBVAC, which contains the antigen repertoire of M. tuberculosis, is now poised to initiate Phase 3 efficacy trials in newborns in TB-endemic countries. BCG''s efficacy extends beyond that against TB, shown to confer heterologous non-specific immunity to other diseases and reduce all-cause mortality in the first months of life. Today, WHO recognises the importance that any new TB vaccine designed for administration at birth, should show similar non-specific benefits as BCG vía mechanisms of trained immunity and/or cross-reactivity of adaptive immune responses to other pathogens. Key recent studies provide strong support for MTBVAC''s ability of inducing trained immunity and conferring non-specific heterologous protection similar to BCG. Research on alternative delivery routes of MTBVAC, such as a clinically feasible aerosol route, could facilitate vaccine administration for long-term TB eradication programmes in the future. © 2021 The Author(s

Paleomagnetic and paleoenvironmental implications of magnetofossil occurrences in late Miocene marine sediments from the Guadalquivir Basin, SW Spain

Although recent studies have revealed more widespread occurrences of magnetofossils in pre-Quaternary sediments than have been previously reported, their significance for paleomagnetic and paleoenvironmental studies is not fully understood. We present a paleo- and rock-magnetic study of late Miocene marine sediments recovered from the Guadalquivir Basin (SW Spain). Well-defined paleomagnetic directions provide a robust magnetostratigraphic chronology for the two studied sediment cores. Rock magnetic results indicate the dominance of intact magnetosome chains throughout the studied sediments. These results provide a link between the highest-quality paleomagnetic directions and higher magnetofossil abundances. We interpret that bacterial magnetite formed in the surface sediment mixed layer and that these magnetic particles gave rise to a paleomagnetic signal in the same way as detrital grains. They, therefore, carry a magnetization that is essentially identical to a post-depositional remanent magnetization, which we term a bio-depositional remanent magnetization. Some studied polarity reversals record paleomagnetic directions with an apparent 60-70 kyr recording delay. Magnetofossils in these cases are interpreted to carry a biogeochemical remanent magnetization that is locked in at greater depth in the sediment column. A sharp decrease in magnetofossil abundance toward the middle of the studied boreholes coincides broadly with a major rise in sediment accumulation rates near the onset of the Messinian salinity crisis (MSC), an event caused by interruption of the connection between the Mediterranean Sea and the Atlantic Ocean. This correlation appears to have resulted from dilution of magnetofossils by enhanced terrigenous inputs that were driven, in turn, by sedimentary changes triggered in the basin at the onset of the MSC. Our results highlight the importance of magnetofossils as carriers of high-quality paleomagnetic and paleoenvironmental signals even in dominantly terrigenous sediments.This study was funded by the Guadaltyc project (MINECO, CGL2012–30875), ARC grant DP120103952, and NSFC grant 41374073

Decadal variability of European sea level extremes in relation to the solar activity

This study investigates the relationship between decadal changes in solar activity and sea level extremes along the European coasts and derived from tide gauge data. Autumn sea level extremes vary with the 11 year solar cycle at Venice as suggested by previous studies, but a similar link is also found at Trieste. In addition, a solar signal in winter sea level extremes is also found at Venice, Trieste, Marseille, Ceuta, Brest, and Newlyn. The influence of the solar cycle is also evident in the sea level extremes derived from a barotropic model with spatial patterns that are consistent with the correlations obtained at the tide gauges. This agreement indicates that the link to the solar cycle is through modulation of the atmospheric forcing. The only atmospheric regional pattern that showed variability at the 11 year period was the East Atlantic pattern

Messinian productivity changes in the northeastern Atlantic and their relationship to the closure of the Atlantic-Mediterranean gateway: implications for Neogene palaeoclimate and palaeoceanography.

The stable isotope composition of planktic and benthic foraminifera and the distribution of selected benthic foraminiferal species from a Messinian record of the lower Guadalquivir Basin, northeastern Atlantic Ocean, show that regional productivity changes were linked to glacioeustatic fluctuations. Glacial periods were characterized by poorly ventilated bottom waters as a result of weak Atlantic Meridional Overturning Circulation (AMOC), and by phases of high productivity related to intensified upwelling. In contrast, wellventilated bottom waters owing to strong AMOC, the presence of degraded organic matter in the upper slope, and high input of degraded terrestrial organic matter derived from fluvial discharge to the outer shelf were recorded during interglacial periods. Before closure of the adjacent Guadalhorce Corridor at 6.18 Ma, which was the final active Betic Atlantic-Mediterranean gateway, the study area was alternately influenced by wellventilated Mediterranean Outflow Water (MOW) and poorly ventilated Atlantic Upwelled Water (AUW). Following closure of the corridor, cessation of the MOW reduced the AMOC and promoted glacial conditions in the northern hemisphere, resulting in the establishment of local upwelling cells

Impact of restriction of the Atlantic-Mediterranean gateway on the Mediterranean Outflow Water and eastern Atlantic circulation during the Messinian

Messinian foraminiferal stable oxygen and carbon isotopes of the Montemayor-1 core (Guadalquivir Basin, SW Spain) have been investigated. This record is exceptional to study the Mediterranean Outflow Water (MOW) impact on the Atlantic meridional overturning circulation (AMOC) and global climate during the Messinian because the core is near the Guadalhorce Corridor, the last Betic gateway to be closed during the early Messinian. Our results allow dating accurately its closure at 6.18 Ma. Constant benthic d18O values, high difference between benthic and planktonic d18O, and low sedimentation rates before 6.18 Ma indicate the presence of a two-layer water column, with bottom winnowing due to an enhanced Mediterranean outflow current. The enhanced contribution of dense MOW to the North Atlantic Ocean likely fostered the formation of North Atlantic Deep Water (NADW). After 6.18 Ma, benthic d18O values parallel that of the global glacioeustatic curve, the difference between benthic and planktonic d18O is low, and sedimentation rates considerably increased. This indicates a good vertical mixing of the water column, interruption of the MOW, and a dominant glacioeustatic control on the isotopic signatures. According to the role of MOW in the modern Atlantic thermohaline circulation, the reduction of the MOW after the closure of the Guadalhorce Corridor might have resulted in a decreased NADW formation rate between 6.0 and 5.5 Ma weakening the AMOC and promoting northern hemisphere cooling. After the Gibraltar Strait opening, the restoration of the MOW and related salt export from the Mediterranean could have promoted an enhanced NADW formation

The nitrogen source as a tool for weeds management

Los resultados de producción de biomasa, tanto de parte aérea como de raíz, nos muestran las distintas preferencias por una u otra fuente [(nitrato (NO3 -) o amonio(NH4 +)] de nitrógeno (N), así como La influencia de la fuente de N en la respuesta a la dosis (2 mM vs. 0,2 mM) en la zona radicular: Amaranthus viridis y Chenopodium album prefieren el NO3- y no responden a la dosis de NH4+, Conyza bonaeriensis y Solanum nigrum también prefieren NO3- pero responden a la dosis de NH4+, mientras que Sonchus oleraceus prefiere el NH4+ y no responde a la dosis de NO3 -. Igualmente, la fuente de N, y no sólo la dosis de N, tiene una gran repercusión en la relación carbono/nitrógeno (C/N) tanto de la parte aérea como de la raíz. El conjunto de los resultados sugiere que el manejo de la fuente de N en los sistemas agrícolas podría ayudar al manejo de las malas hierbas y con ello a su control, en pro de hacer una mejor optimización de los recursos.The results of biomass production both in terms of shoot and root, show distinct plants preferences for the nitrogen source; Amaranthus viridis and Chenopodium album prefers NO3 - and does not respond to the dose of NH4 +, Conyza bonaeriensis and Solanum nigrum also prefers NO3 - but respond to the dose of NH4 +, and finally Sonchus oleraceus prefers NH4 + over NO3 - and does not respond to the dose of NO3 -. Here, we also show that the source of N has a major role in plant N and C concentration. Overall, these results indicate that N fertilization (source and dose) may be a tool for the management of weeds in agricultural system where the farmer has control over the source of N applied