Miniature shock tube for laser driven shocks

International audienceWe describe in this paper the design of a miniature shock tube (smaller than 1 cm3) that can be placed in a vacuum vessel and allows transverse optical probing and longitudinal backside XUV emission spectroscopy. Typical application is the study of laser launched radiative shocks, in the framework of what is called "laboratory Astrophysics"

Experimental study of radiative shocks at PALS facility

We report on the investigation of strong radiative shocks generated with the high energy, sub-nanosecond iodine laser at PALS. These shock waves are characterized by a developed radiative precursor and their dynamics is analyzed over long time scales (~50 ns), approaching a quasi-stationary limit. We present the first preliminary results on the rear side XUV spectroscopy. These studies are relevant to the understanding of the spectroscopic signatures of accretion shocks in Classical T Tauri Stars.Comment: 21 pages, 1 table, 7 figure

Analysis of BAC-end sequences in rainbow trout: Content characterization and assessment of synteny between trout and other fish genomes

<p>Abstract</p> <p>Background</p> <p>Rainbow trout (<it>Oncorhynchus mykiss</it>) are cultivated worldwide for aquaculture production and are widely used as a model species to gain knowledge of many aspects of fish biology. The common ancestor of the salmonids experienced a whole genome duplication event, making extant salmonids such as the rainbow trout an excellent model for studying the evolution of tetraploidization and re-diploidization in vertebrates. However, the lack of a reference genome sequence hampers research progress for both academic and applied purposes. In order to enrich the genomic tools already available in this species and provide further insight on the complexity of its genome, we sequenced a large number of rainbow trout BAC-end sequences (BES) and characterized their contents.</p> <p>Results</p> <p>A total of 176,485 high quality BES, were generated, representing approximately 4% of the trout genome. BES analyses identified 6,848 simple sequence repeats (SSRs), of which 3,854 had high quality flanking sequences for PCR primers design. The first rainbow trout repeat elements database (INRA RT rep1.0) containing 735 putative repeat elements was developed, and identified almost 59.5% of the BES database in base-pairs as repetitive sequence. Approximately 55% of the BES reads (97,846) had more than 100 base pairs of contiguous non-repetitive sequences. The fractions of the 97,846 non-repetitive trout BES reads that had significant BLASTN hits against the zebrafish, medaka and stickleback genome databases were 15%, 16.2% and 17.9%, respectively, while the fractions of the non-repetitive BES reads that had significant BLASTX hits against the zebrafish, medaka, and stickleback protein databases were 10.7%, 9.5% and 9.5%, respectively. Comparative genomics using paired BAC-ends revealed several regions of conserved synteny across all the fish species analyzed in this study.</p> <p>Conclusions</p> <p>The characterization of BES provided insights on the rainbow trout genome. The discovery of specific repeat elements will facilitate analyses of sequence content (e.g. for SNPs discovery and for transcriptome characterization) and future genome sequence assemblies. The numerous microsatellites will facilitate integration of the linkage and physical maps and serve as valuable resource for fine mapping QTL and positional cloning of genes affecting aquaculture production traits. Furthermore, comparative genomics through BES can be used for identifying positional candidate genes from QTL mapping studies, aid in future assembly of a reference genome sequence and elucidating sequence content and complexity in the rainbow trout genome.</p

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Interaction of a highly radiative shock with a solid obstacle

International audienc

Phylogenetic relationships of Pleurotus species according to the sequence and secondary structure of the mitochondrial small-subunit rRNA V4, V6 and V9 domains The GenBank accession numbers for the sequences reported in this paper are given in Methods.

International audienc

Effect of lateral radiative losses on radiative shock propagation

International audienceExperimental and numerical studies of radiative shocks, of interest as scaled astrophysical objects, have been performed. Experiments were conducted at the PALS facility in Prague with a xenon filled mini-shock tube using a laser accelerated plastic pusher. Numerical simulations of the hydrodynamics including radiation effects have been performed with the 3D code HERACLES. Measurements have been made of the electronic density of the shocked gas and of the time history of the position of the radiative precursor. Simulations and experimental results show good agreement when lateral radiative losses are taken into account, including a wall albedo of 40%

New insights on the physics of radiative shocks

International audienceShock waves play a significant role in several astrophysical phenomena. Among them, Radiative shocks are strong shocks, in which the shock front is heated to very high temperature and thus emit an important radiation flux. The interesting feature of the radiative shocks is that their structure is strongly influenced by the coupling between hydrodynamics and radiation. They occur in astrophysical system in the different stages of the stellar evolution, for instance during the accretion processes in the stellar infancy, and are studied in high-energy density laboratory experiments using kJ class lasers. Such laser facilities enable to drive shocks in which the radiative flux may prevail hydrodynamic mechanism of energy transfer. Typical irradiances of 10**14 W.cm-2, allows to produce radiative shocks in high atomic gas medium at low pressure, where the important radiation generated by the shocked plasma leads to the formation of an ionizing wave, also call radiative precursor, in the cold upstream xenon. I will present new experimental results realized on the PALS laser installation aiming at improving the present knowledge of these complex flows. The greatest attention is paid to the application of to new diagnostics, namely, the instantaneous imaging of the whole shock structure using an auxiliary laser at 21.2 nm and a time-and-space resolved plasma self-emission using fast diodes. This work is supported by french ANR STARSHOCK (grant 08-BLAN-0263-07) and by Laserlab-Europe II programme