79 research outputs found

    Wind-induced Cross-Strait Sea Level Variability in the Strait of Gibraltar using Coastal Altimetry and In-Situ Measurements

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    In this work, we retracked altimeter waveforms of ESA satellites. ERS2 RA and Envisat RA2 from descending track 0360 over the eastern side of the Strait of Gibraltar using the Adaptive Leading Edge Subwaveform ALES retracker

    Fast electron transport patterns in intense laser-irradiated solids diagnosed by modeling measured multi-MeV proton beams

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    The measured spatial-intensity distribution of the beam of protons accelerated from the rear side of a solid target irradiated by an intense (>10 Wcm) laser pulse provides a diagnostic of the two-dimensional fast electron density profile at the target rear surface and thus the fast electron beam transport pattern within the target. An analytical model is developed, accounting for rear-surface fast electron sheath dynamics, ionization and projection of the resulting beam of protons. The sensitivity of the spatial-intensity distribution of the proton beam to the fast electron density distribution is investigated. An annular fast electron beam transport pattern with filamentary structure is inferred for the case of a thick diamond target irradiated at a peak laser intensity of 6 × 10 Wcm

    Radiation pressure-driven plasma surface dynamics in ultra-intense laser pulse interactions with ultra-thin foils

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    The dynamics of the plasma critical density surface in an ultra-thin foil target irradiated by an ultra-intense ( ∌ 6 × 1020 Wcm−2 ) laser pulse is investigated experimentally and via 2D particle-in- cell simulations. Changes to the surface motion are diagnosed as a function of foil thickness. The experimental and numerical results are compared with hole-boring and light-sail models of radi- ation pressure acceleration, to identify the foil thickness range for which each model accounts for the measured surface motion. Both the experimental and numerical results show that the onset of relativistic self-induced transparency, in the thinnest targets investigated, limits the velocity of the critical surface, and thus the e ff ectiveness of radiation pressure acceleration

    An optically multiplexed single-shot time-resolved probe of laser–plasma dynamics

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    We introduce a new approach to temporally resolve ultrafast micron-scale processes via the use of a multi-channel optical probe. We demonstrate that this technique enables highly precise time-resolved, two-dimensional spatial imaging of intense laser pulse propagation dynamics, plasma formation and laser beam filamentation within a single pulse over four distinct time frames. The design, development and optimization of the optical probe system is presented, as are representative experimental results from the first implementation of the multi-channel probe with a high-power laser pulse interaction with a helium gas jet target

    Influence of laser polarization on collective electron dynamics in ultraintense laser-foil interactions

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    The collective response of electrons in an ultrathin foil target irradiated by an ultraintense laser pulse is investigated experimentally and via 3D particle-in-cell simulations. It is shown that if the target is sufficiently thin that the laser induces significant radiation pressure, but not thin enough to become relativistically transparent to the laser light, the resulting relativistic electron beam is elliptical, with the major axis of the ellipse directed along the laser polarization axis. When the target thickness is decreased such that it becomes relativistically transparent early in the interaction with the laser pulse, diffraction of the transmitted laser light occurs through a so called 'relativistic plasma aperture', inducing structure in the spatial-intensity profile of the beam of energetic electrons. It is shown that the electron beam profile can be modified by variation of the target thickness and degree of ellipticity in the laser polarization

    Towards optical polarization control of laser-driven proton acceleration in foils undergoing relativistic transparency

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    Control of the collective response of plasma particles to intense laser light is intrinsic to relativistic optics, the development of compact laser-driven particle and radiation sources, as well as investigations of some laboratory astrophysics phenomena. We recently demonstrated that a relativistic plasma aperture produced in an ultra-thin foil at the focus of intense laser radiation can induce diffraction, enabling polarization-based control of the collective motion of plasma electrons. Here we show that under these conditions the electron dynamics are mapped into the beam of protons accelerated via strong charge-separation-induced electrostatic fields. It is demonstrated experimentally and numerically via 3D particle-in-cell simulations that the degree of ellipticity of the laser polarization strongly influences the spatial-intensity distribution of the beam of multi-MeV protons. The influence on both sheath accelerated and radiation pressure accelerated protons is investigated. This approach opens up new routes to control laser-driven ion sources

    TRY plant trait database – enhanced coverage and open access

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    Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

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    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

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    In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field
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