Autophagy is activated and involved in cell death with participation of cathepsins during stress-induced microspore embryogenesis in barley

Microspores are reprogrammed towards embryogenesis by stress. Many microspores die after this stress, limiting the efficiency of microspore embryogenesis. Autophagy is a degradation pathway that plays critical roles in stress response and cell death. In animals, cathepsins have an integral role in autophagy by degrading autophagic material; less is known in plants. Plant cathepsins are papain-like C1A cysteine proteases involved in many physiological processes, including programmed cell death. We have analysed the involvement of autophagy in cell death, in relation to cathepsin activation, during stress-induced microspore embryogenesis in Hordeum vulgare. After stress, reactive oxygen species (ROS) and cell death increased and autophagy was activated, including HvATG5 and HvATG6 up-regulation and increase of ATG5, ATG8, and autophagosomes. Concomitantly, cathepsin L/F-, B-, and H-like activities were induced, cathepsin-like genes HvPap-1 and HvPap-6 were up-regulated, and HvPap-1, HvPap-6, and HvPap-19 proteins increased and localized in the cytoplasm, resembling autophagy structures. Inhibitors of autophagy and cysteine proteases reduced cell death and promoted embryogenesis. The findings reveal a role for autophagy in stress-induced cell death during microspore embryogenesis, and the participation of cathepsins. Similar patterns of activation, expression, and localization suggest a possible connection between cathepsins and autophagy. The results open up new possibilities to enhance microspore embryogenesis efficiency with autophagy and/or cysteine protease modulators.España, MINECO AGL2014-52028-R and AGL2017-82447-

Advanced design features of Doherty power amplifiers

A Doherty power amplifier (DPA) is an effective structure born in 1936 which, after a scarce revival around year 2000), had been strengthened from 2005 because its capability to combine linear amplification with power efficiency. Despite the conceptual simplicity of its basic operation, a lot of practical drawbacks shrink the theoretical behavior, thus leading a significant number of research works to overcome them. The main objective in DPA research is to increase efficiency while maintaining linearity and filling the specified bandwidth. This paper presents a survey of the state of the art of DPA advanced design aspects. After a short review of the DPA operation principles, aspects regarding improvements for linearity, power efficiency and amplification bandwidth are introduced. Besides, some alternative structures and technologies, as well as practical design aspects and some trade-offs which the designer usually has to face are also presented.Peer ReviewedPostprint (published version

A method for real-time generation of slew-rate limited envelopes in envelope tracking transmitters

Postprint (published version

Spatiotemporal Precipitation Estimation from Rain Gauges and Meteorological Radar Using Geostatistics

[EN] Automatic interpolation of precipitation maps combining rain gauge and radar data has been done in the past but considering only the data collected at a given time interval. Since radar and rain gauge data are collected at short intervals, a natural extension of previous works is to account for temporal correlations and to include time into the interpolation process. In this work, rainfall is interpolated using data from the current time interval and the previous one. Interpolation is carried out using kriging with external drift, in which the radar rainfall estimate is the drift, and the mean precipitation is set to zero at the locations where the radar estimate is zero. The rainfall covariance is modeled as non-stationary in time, and the space system of reference moves with the storm. This movement serves to maximize the collocated correlation between consecutive time intervals. The proposed approach is analyzed for four episodes that took place in Catalonia (Spain). It is compared with three other approaches: (i) radar estimation, (ii) kriging with external drift using only the data from the same time interval, and (iii) kriging with external drift using data from two consecutive time intervals but not accounting for the displacement of the storm. The comparisons are performed using cross-validation. In all four episodes, the proposed approach outperforms the other three approaches. It is important to account for temporal correlation and use a Lagrangian system of coordinates that tracks the rainfall movement.This work has been done in the framework of the Spanish Project FFHazF (CGL2014-60700) and the EC H2020 project ANYWHERE (DRS-1-2015-700099). Thanks are due to the Meteorological Service of Catalonia for providing the radar and rain gauges data used here.Cassiraga, EF.; Gómez-Hernández, JJ.; Berenguer, M.; Sempere-Torres, D.; Rodrigo-Ilarri, J. (2021). Spatiotemporal Precipitation Estimation from Rain Gauges and Meteorological Radar Using Geostatistics. Mathematical Geosciences. 53(4):499-516. https://doi.org/10.1007/s11004-020-09882-1S499516534Aran M, Amaro J, Arús J, Bech J, Figuerola F, Gayà M, Vilaclara E (2009) Synoptic and mesoscale diagnosis of a tornado event in Castellcir, Catalonia, on 18th October 2006. Atmos Res 93:147–160Azimi-Zonooz A, Krajewski W, Bowles D, Seo D (1989) Spatial rainfall estimation by linear and non-linear co-kriging of radar-rainfall and raingage data. Stoch Hydrol Hydraul 3:51–67Bech J, Pascual R, Rigo T, Pineda N, López J, Arús J, Gayá M (2007) An observational study of the 7 September 2005 Barcelona Tornado outbreak. Nat Hazards Earth Syst Sci 7:129–139Bech J, Pineda N, Rigo T, Aran M, Amaro J, Gayà M, Arús J, Montanyà J, van der Velde O (2011) A mediterranean nocturnal heavy rainfall and tornadic event. Part I: overview, damage survey and radar analysis. Atmos Res 100:621–637Berenguer M, Sempere-Torres D, Pegram GG (2011) Sbmcast-an ensemble nowcasting technique to assess the uncertainty in rainfall forecasts by Lagrangian extrapolation. J Hydrol 404:226–240Berenguer M, Sempere-Torres D, Hürlimann M (2015) Debris-flow forecasting at regional scale by combining susceptibility mapping and radar rainfall. Nat Hazards Earth Syst Sci 15:587–602Bochner S (1949) Fourier transforms. Princeton University Press, London, p 219Brown PE, Diggle PJ, Lord ME, Young PC (2001) Space–time calibration of radar rainfall data. J R Stat Soc Ser C 50:221–241Calheiros R, Zawadzki I (1987) Reflectivity-rain rate relationships for radar hydrology in Brazil. J Climate Appl Meteorol 26:118–132Chumchean S, Seed A, Sharma A (2006) Correcting of real-time radar rainfall bias using a Kalman filtering approach. J Hydrol 317:123–137Corral C, Velasco D, Forcadell D, Sempere-Torres D, Velasco E (2009) Advances in radar-based flood warning systems. the EHIMI system and the experience in the Besòs flash-flood pilot basinCreutin J, Delrieu G, Lebel T (1988) Rain measurement by raingage-radar combination: a geostatistical approach. J Atmos Ocean Technol 5:102–115Delrieu G, Annette W, Brice B, Dominique F, Laurent B, Pierre-Emmanuel K (2014) Geostatistical radar-raingauge merging: a novel method for the quantification of rain estimation accuracy. Adv Water Resour 71:110–124Deutsch C (1991) The relationship between universal kriging, kriging with an external drift and cokriging. SCRF report 4Germann U, Turner B, Zawadzki I (2006) Predictability of precipitation from continental radar images. Part IV: limits to prediction. J Atmos Sci 63:2092–2108Goudenhoofdt E, Delobbe L (2009) Evaluation of radar-gauge merging methods for quantitative precipitation estimates. Hydrol Earth Syst Sci 13:195–203Harrold T, Austin P (1974) The structure of precipitation systems—a review. J Rech Atmos 8:41–57Hevesi JA, Istok JD, Flint AL (1992a) Precipitation estimation in mountainous terrain using multivariate geostatistics. Part I: structural analysis. J Appl Meteorol 31:661–676Hevesi JA, Istok JD, Flint AL (1992b) Precipitation estimation in mountanious terrain using multivariate geostatistics. Part II: isohyetal maps. J Appl Meteorol 31:677–688Jewell SA, Gaussiat N (2015) An assessment of kriging-based rain-gauge-radar merging techniques. Q J R Meteorol Soc 141:2300–2313Journel AG, Rossi M (1989) When do we need a trend model in kriging? Math Geol 21:715–739Krajewski WF (1987) Cokriging radar-rainfall and rain gage data. J Geophys Res Atmos 92:9571–9580Mateo J, Ballart D, Brucet C, Aran M, Bech J (2009) A study of a heavy rainfall event and a tornado outbreak during the passage of a squall line over Catalonia. Atmos Res 93:131–146Pulkkinen S, Koistinen J, Kuitunen T, Harri AM (2016) Probabilistic radar-gauge merging by multivariate spatiotemporal techniques. J Hydrol 542:662–678Rinehart R, Garvey E (1978) Three-dimensional storm motion detection by conventional weather radar. Nature 273:287Rosenfeld D, Wolff DB, Atlas D (1993) General probability-matched relations between radar reflectivity and rain rate. J Appl Meteorol 32:50–72Rosenfeld D, Wolff DB, Amitai E (1994) The window probability matching method for rainfall measurements with radar. J Appl Meteorol 33:682–693Rosenfeld D, Amitai E, Wolff DB (1995) Improved accuracy of radar WPMM estimated rainfall upon application of objective classification criteria. J Appl Meteorol 34:212–223Sempere-Torres D, Corral C, Raso J, Malgrat P (1999) Use of weather radar for combined sewer overflows monitoring and control. J Environ Eng 125:372–380Seo DJ (1998) Real-time estimation of rainfall fields using radar rainfall and rain gage data. J Hydrol 208:37–52Seo DJ, Krajewski WF, Bowles DS (1990) Stochastic interpolation of rainfall data from rain gages and radar using cokriging: 1. Design of experiments. Water Resour Res 26:469–477Sideris I, Gabella M, Erdin R, Germann U (2014) Real-time radar-rain-gauge merging using spatio-temporal co-kriging with external drift in the alpine terrain of Switzerland. Q J R Meteorol Soc 140:1097–1111Sinclair S, Pegram G (2005) Combining radar and rain gauge rainfall estimates using conditional merging. Atmos Sci Lett 6:19–22Sun X, Mein R, Keenan T, Elliott J (2000) Flood estimation using radar and raingauge data. J Hydrol 239:4–18Todini E (2001) A bayesian technique for conditioning radar precipitation estimates to rain-gauge measurements. Hydrol Earth Syst Sci Dis 5:187–199Velasco-Forero CA, Sempere-Torres D, Cassiraga EF, Gómez-Hernández JJ (2009) A non-parametric automatic blending methodology to estimate rainfall fields from rain gauge and radar data. Adv Water Resour 32:986–1002Wilson JW, Brandes EA (1979) Radar measurement of rainfall—a summary. Bull Am Meteorol Soc 60:1048–1060Yao T, Journel AG (1998) Automatic modeling of (cross) covariance tables using fast fourier transform. Math Geol 30:589–615Yoon SS, Bae DH (2013) Optimal rainfall estimation by considering elevation in the Han River Basin, South Korea. J Appl Meteorol Climatol 52:802–818Zawadzki I (1973) Statistical properties of precipitation patterns. J Appl Meteorol 12:459–47

Improvement of Up-converters linearity for Ka-band operation

The application of a digital predistorter to the linearisation of a Ka-band mixer is presented herein. The general objective in the TX design is to get the best trade-off between linearity and costs. This require the most of the simplicity and possibly to take advantage from already existing device without perturbing its other functionalities. After a presentation of the problem and its constraints, we present the digital predistorter, which has been tested and debugged by means of IEEE-488 bus (GPIB) controllable instrumentation (EMA, electronic measuring automation) in order to finally consider its implementation on a fast newgeneration FPGA device. Results show an increment of the linear zone in the up-converter AM-AM curve, of about 15 dB

Nanoarchitectures Based on Layered Titanosilicates Supported on Glass Fibers: Application to Hydrogen Storage

This work reports on the synthesis of nanosheets of layered titanosilicate JDF-L1 supported on commercial E-type glass fibers with the aim of developing novel nanoarchitectures useful as robust and easy to handle hydrogen adsorbents. The preparation of those materials is carried out by hydrothermal reaction from the corresponding gel precursor in the presence of the glass support. Because of the basic character of the synthesis media, silica from the silicate-based glass fibers can be involved in the reaction, cementing its associated titanosilicate and giving rise to strong linkages on the support with the result of very stable heterostructures. The nanoarchitectures built up by this approach promote the growth and disposition of the titanosilicate nanosheets as a house-of-cards radially distributed around the fiber axis. Such an open arrangement represents suitable geometry for potential uses in adsorption and catalytic applications where the active surface has to be available. The content of the titanosilicate crystalline phase in the system represents about 12 wt %, and this percentage of the adsorbent fraction can achieve, at 298 K and 20 MPa, 0.14 wt % hydrogen adsorption with respect to the total mass of the system. Following postsynthesis treatments, small amounts of Pd (<0.1 wt %) have been incorporated into the resulting nanoarchitectures in order to improve their hydrogen adsorption capacity. In this way, Pd-layered titanosilicate supported on glass fibers has been tested as a hydrogen adsorbent at diverse pressures and temperatures, giving rise to values around 0.46 wt % at 298 K and 20 MPa. A mechanism of hydrogen spillover involving the titanosilicate framework and the Pd nanoparticules has been proposed to explain the high increase in the hydrogen uptake capacity after the incorporation of Pd into the nanoarchitecture.We thank the CICYT (Spain, projects MAT2009-09960 and MAT2012-31759), Obra Social la Caixa, Aragon Government (GA-LC-019/2011), ESF, Generalitat Valenciana, and FEDER (PROMETEO/2009/047) for financial support. J.P.-C. is grateful for a Ph.D. grant (FPI, BES-2010-038410) from the Spanish Ministerio de Ciencia e Innovación

On passive bias networks for drain-modulated power amplifiers

Postprint (published version

Smooth and rough platinum deposits resulting from the electroreduction of hydrous oxide platinum overlayers : A mechanistic approach

The electroreduction of thick platinum oxides accumulated by the application of a fast square wave perturbing potential in 0.5 M H2SO4 was studied by using potentiodynamic and potentiostatic techniques complemented with scanning electron miscroscopy. The electroreduction process can be unambigously explained through an instantaneous nucleation and 3-D growth of right circular cones under charge transfer control where diffusion of reacting species to the growing centres is essential for further expansion. The growth mode of the Pt crystallites either smooth or rough depends on the electroreduction conditions. The rought/smooth modes of growth result from the influence of the electric field on the transport of particles in the reaction region and on the supersaturation concentration operating during the electrocrystallization process.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

A comparative study of electrochemical and optical properties of rhenium deposited on gold and platinum

Rhenium-containing films were grown on gold and platinum after different potentiostatic and potentiodynamic polarizations in the - 0.20 V to 0.70 V range (vs rhe) in aqueous acid perrhenate. Experimental data were obtained using cyclic voltammetry and ellipsometry, from which the thickness and optical indices of the electrodeposited rhenium layer were calculated. Metallic rhenium deposition on gold takes place at potentials within the hydrogen evolution reaction. Rhenium oxide on platinum is formed in the hydrogen adatom potential domain, whereas metallic rhenium is deposited concurrently with the hydrogen adsorption and evolution reactions on the same metal.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

A comparative study of electrochemical and optical properties of rhenium deposited on gold and platinum

Rhenium-containing films were grown on gold and platinum after different potentiostatic and potentiodynamic polarizations in the - 0.20 V to 0.70 V range (vs rhe) in aqueous acid perrhenate. Experimental data were obtained using cyclic voltammetry and ellipsometry, from which the thickness and optical indices of the electrodeposited rhenium layer were calculated. Metallic rhenium deposition on gold takes place at potentials within the hydrogen evolution reaction. Rhenium oxide on platinum is formed in the hydrogen adatom potential domain, whereas metallic rhenium is deposited concurrently with the hydrogen adsorption and evolution reactions on the same metal.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada