Absence of Cu–Zn superoxide dismutase BCSOD1 reduces Botrytiscinerea virulence in Arabidopsis and tomato plants, revealinginterplay among reactive oxygen species, callose and signallingpathways

Plants activate responses against pathogens, including the oxida-tive burst. Necrotrophic pathogens can produce reactive oxygenspecies (ROS) that benefit the colonization process. Previously, wehave demonstrated that tomato plants challenged with Botrytiscinerea accumulate ROS and callose, together with the inductionof genes involved in defence, signalling and oxidative metabolism.Here, we studied the infection phenotype of the Dbcs od1 strain inboth tomato and Arabidopsis plants. This mutant lacks bcsod1,which encodes Cu–Zn superoxide dismutase (SOD). This enzymecatalyses the conversion of superoxide ion (O–2) into hydrogen per-oxide (H2O2). ROS play a protective role and act as signals inplants. Dbcsod1 displayed reduced virulence compared with wild-type B05.10 in both species. Plants infected with Dbcsod1 accu-mulated less H2O2and more O–2than those infected with B05.10,which is associated with an increase in the defensive polymer cal-lose. This supports a major role of fungal SOD in H2O2productionduring the plant–pathogen interaction. The early induction of thecallose synthase gene PMR4 suggested that changes in ROSaltered plant defensive responses at the transcriptional level. Themetabolites and genes involved in signalling and in response tooxidative stress were differentially expressed on Dbcsod1 infec-tion, supporting the notion that plants perceive changes in ROSbalance and activate defence responses. A higher O2–/H2O2ratioseems to be beneficial for plant protection against this necrotroph.Our results highlight the relevance of callose and the oxylipin 12-oxo-phytodienoic acid (OPDA) in the response to changes in theoxidative environment, and clarify the mechanisms that underliethe responses to Botrytis in Arabidopsis and tomato plants.This work was supported by grants from the Spanish Ministry of Scienceand Innovation (AGL2010-22300-C03-01-02 and AGL2013-49023-C03-01-02), co-funded by the European Regional Development Funds (ERDF)and by Generalitat Valenciana Grupos de Excelencia PROMETEO/2012/066. J.L.-C. and O.C.-S. were recipients of research contracts from thePROMETEO/2012/066 grant. E.F.-C. was the recipient of research con-tracts from grant AGL2010-22300-C03-01. J.L.-C. is the recipient of aresearch contract from grant AGL2013-49023-C03-01

Continuous spectra in high-harmonic generation driven by multicycle laser pulses

We present observations of the emission of XUV continua in the 20-37 eV region by high harmonic generation (HHG) with $4$-$7\ \mathrm{fs}$ pulses focused onto a Kr gas jet. The underlying mechanism relies on coherent control of the relative delays and phases between individually generated attosecond pulse, achievable by adjusting the chirp of the driving pulses and the interaction geometry. Under adequate negative chirp and phase matching conditions, the resulting interpulse interference yields a continuum XUV spectrum, which is due to both microscopic and macroscopic (propagation) contributions. This technique opens the route for modifying the phase of individual attosecond pulses and for the coherent synthesis of XUV continua from multicycle driving laser pulses without the need of an isolated attosecond burst.Comment: 14 pages, 5 figures. Submitted to Physical Review

Dispersal-induced resilience to stochastic environmental fluctuations in populations with Allee effect

Many species are unsustainable at small population densities (Allee Effect). This implies that for population densities below a threshold, named Allee threshold, the population decreases instead of growing. In a closed local population, this makes that environmental fluctuations always leads to extinction. Here, we show how, in spatially extended habitats, dispersal can lead to a sustainable population in a region, provided the amplitude of environmental fluctuations is below an extinction threshold. We have identified two types of sustainable populations: high-density and low-density populations (through a mean-field approximation, valid in the limit of large dispersal length). Our results show that close to global extinction patches where population density is high, low or extinct coexist (even for homogeneous habitats). The extinction threshold increases proportionally to the squared root of the dispersal rate, decreases with the Allee threshold, and it is maximum for characteristic dispersal distances much larger than the spatial scale of synchrony of environmental fluctuations. The low-density population solution can be particularly interesting for future applications, as to understand non-recovery events after harvesting. This theoretical framework allows novel approaches to address the impact of other factors, as habitat fragmentation, on the population resilience to environmental fluctuations.Comment: 24 pages, 3 figures, 1 tabl

Giant magnetic anisotropy at nanoscale: overcoming the superparamagnetic limit

It has been recently observed for palladium and gold nanoparticles, that the magnetic moment at constant applied field does not change with temperature over the range comprised between 5 and 300 K. These samples with size smaller than 2.5 nm exhibit remanence up to room temperature. The permanent magnetism for so small samples up to so high temperatures has been explained as due to blocking of local magnetic moment by giant magnetic anisotropies. In this report we show, by analysing the anisotropy of thiol capped gold films, that the orbital momentum induced at the surface conduction electrons is crucial to understand the observed giant anisotropy. The orbital motion is driven by localised charge and/or spin through spin orbit interaction, that reaches extremely high values at the surfaces. The induced orbital moment gives rise to an effective field of the order of 103 T that is responsible of the giant anisotropy.Comment: 15 pages, 2 figures, submitted to PR

Magnetic and superconducting phase diagrams in ErNi2B2C

We present measurements of the superconducting upper critical field Hc2(T) and the magnetic phase diagram of the superconductor ErNi2B2C made with a scanning tunneling microscope (STM). The magnetic field was applied in the basal plane of the tetragonal crystal structure. We have found large gapless regions in the superconducting phase diagram of ErNi2B2C, extending between different magnetic transitions. A close correlation between magnetic transitions and Hc2(T) is found, showing that superconductivity is strongly linked to magnetism.Comment: 5 pages, 4 figure

On the Performance of Interleavers for Quantum Turbo Codes

Quantum turbo codes (QTC) have shown excellent error correction capabilities in the setting of quantum communication, achieving a performance less than 1 dB away from their corresponding hashing bounds. Existing QTCs have been constructed using uniform random interleavers. However, interleaver design plays an important role in the optimization of classical turbo codes. Consequently, inspired by the widely used classical-to-quantum isomorphism, this paper studies the integration of classical interleaving design methods into the paradigm of quantum turbo coding. Simulations results demonstrate that error floors in QTCs can be lowered significantly, while decreasing memory consumption, by proper interleaving design without increasing the overall decoding complexity of the system

La utilización del vídeo para la enseñanza de conceptos básicos (calor y temperatura)

The goal of one of the inquiries implemented in the ANTEC Project (Aplicación de las Nuevas Tecnologías a la Enseñanza de las Ciencias) was to analyze the use of vídeotapes as a means to teach Sciences. In this paper we present the use of vídeotapes related to Heat and Temperature Units, in classrooms with students who were 16 years old. We expected to modify their concepts about these subjects. The results suggest the improvement of students' concepts and vocabulary, although it was not the same with the application of scientific knowledge to everyday events

Combining the Burrows-Wheeler Transform and RCM-LDGM Codes for the Transmission of Sources with Memory at High Spectral Efficiencies

In this paper, we look at the problem of implementing high-throughput Joint SourceChannel (JSC) coding schemes for the transmission of binary sources with memory over AWGN channels. The sources are modeled either by a Markov chain (MC) or a hidden Markov model (HMM). We propose a coding scheme based on the Burrows-Wheeler Transform (BWT) and the parallel concatenation of Rate-Compatible Modulation and Low-Density Generator Matrix (RCM-LDGM) codes. The proposed scheme uses the BWT to convert the original source with memory into a set of independent non-uniform Discrete Memoryless (DMS) binary sources, which are then separately encoded, with optimal rates, using RCM-LDGM codes