Turbulent spectra and spectral kinks in the transition range from MHD to kinetic Alfv\'en turbulence

A weakly dispersive sub-range (WDR) of kinetic Alfv\'en turbulence is distinguished and investigated for the first time in the context of MHD/kinetic turbulence transition. We found perpendicular wavenumber spectra ~ k^{-3} and ~ k^{-4} formed in WDR by strong and weak turbulence of kinetic Alfv\'en waves (KAWs), respectively. These steep WDR spectra connect shallower spectra in the MHD and strongly dispersive KAW sub-ranges, which results in a specific double-kink (2-k) pattern often seen in observed turbulent spectra. The first kink occurs where MHD turbulence transforms into weakly dispersive KAW turbulence; the second one is between weakly and strongly dispersive KAW sub-ranges. Our analysis suggests that the partial turbulence dissipation due to amplitude-dependent super-adiabatic ion heating may occur in the vicinity of the first spectral kink. A threshold-like nature of this process results in a conditional selective dissipation affecting only largest over-threshold amplitudes and decreasing intermittency in the range below the first spectral kink. Several recent counter-intuitive observational findings can be explained by the selective dissipation coupled to the nonlinear interaction among weakly dispersive KAWs.Comment: 11 pages, 3 figure

Non-resonant Alfv\'enic instability activated by high temperature of ion beams in compensated-current astrophysical plasmas

Context: Compensated-current systems are established in response to hot ion beams in terrestrial foreshock regions, around supernova remnants, and in other space and astrophysical plasmas. Aims: We study a non-resonant reactive instability of Alfv\'en waves (AWs) propagating quasi-parallel to the background magnetic field $\mathbf{B}_{0}$ in such systems. Methods: The instability is investigated analytically in the framework of kinetic theory applied to the hydrogen plasmas penetrated by hot proton beams. Results: The instability arises at parallel wavenumbers $k_{z}$ that are sufficiently large to demagnetize the beam ions, $k_{z}V_{Tb}/\omega_{Bi}\gtrsim$ $1$ (here $V_{Tb}$ is the beam thermal speed along $\mathbf{B}_{0}$ and $\omega _{Bi}$ is the ion-cyclotron frequency). The Alfv\'en mode is then made unstable by the imbalance of perturbed currents carried by the magnetized background electrons and partially demagnetized beam ions. The destabilizing effects of the beam temperature and the temperature dependence of the instability threshold and growth rate are demonstrated for the first time. The beam temperature, density, and bulk speed are all destabilizing and can be combined in a single destabilizing factor $\alpha_{b}$ triggering the instability at {$\alpha _{b}>$ $\alpha _{b}^{\mathrm{thr}}$}, where the threshold varies in a narrow range $2.43\leq$ $\alpha _{b}^{\mathrm{thr}}\leq$ $4.87$. New analytical expressions for the instability growth rate and its boundary in the parameter space are obtained and can be directly compared with observations. Two applications to terrestrial foreshocks and foreshocks around supernova remnants are shortly discussed. In particular, our results suggest that the ions reflected by the shocks around supernova remnants can drive stronger instability than the cosmic rays

An asymmetric protoplast fusion and screening method for generating celeriac cybrids

Celeriac F1 hybrid seed production is currently complicated due to the instability of cytoplasmic male sterile lines. To develop alternative alloplasmic CMS lines, an asymmetric protoplast fusion and hybrid screening methodology was established. Celeriac suspension cells protoplasts were used as the acceptor and carrot, coriander and white celery mesophyll protoplasts as the donor for protoplast fusion experiments. Acceptor cytoplasmic inheritance was inhibited by iodoacetamide treatment and donor nuclear genome inheritance was prevented by UV exposure. Protoplasts were selectively stained and fused using electroporation and polyethylene glycol, and candidate hybrid shoots were obtained. One chloroplast and three mitochondrial markers that could distinguish acceptor and donors organelles were used to characterize over 600 plants obtained after fusion events, without identifying any cybrid. In order to increase the testing efficiency a high number of micro plantlets were pooled and hence the presence of the carrot specific Atp1 marker in one of the pooled samples was detected. We demonstrated that fusion took place between celeriac and a carrot indicating that the creation of viable hybrids is possible although at a very low frequency. These findings open the path for new cytoplasmic hybridization and the isolation of novel CMS lines of celeriac

Segregation of rol genes in two generations of Sinningia speciosa engineered through wild type Rhizobium rhizogenes

Rhizobium rhizogenes infects and transforms a wide range of plant species. It thereby introduces new genes located on transfer-DNA of the root inducing plasmid (pRi) into the plant genome and one of its abilities is to alter the host root system. Explants from pRi transformed roots from Sinningia speciosa were regenerated to create naturally transgenic Ri lines. The presence of rol and aux genes in the Ri lines was linked with altered growth characteristics: shorter peduncles, wrinkled leaves, delayed flowering and enhanced root growth. The potential of Ri lines for breeding was evaluated through consecutive backcrossing with the original host genotype. The progeny of reciprocal crosses showed non-Mendelian inheritance suggesting partial transmission of the of the aux and rol genes. The typical Ri phenotype observed in the primary Ri line was partially inherited. These results revealed that the Ri phenotype is a complex trait influenced by the genetic background of the Ri line

Introgression of rol genes from rhizogenic Agrobacterium strains into Escallonia spp.

The introgression of rol-genes of rhizogenic Agrobacterium into the plant genome induces changes in plant phenotype and physiology. However, only limited experience with this technique is available for woody ornamentals. To induce new variation within the Escallonia genus, several species were co-cultivated with rhizogenic Agrobacterium strains. Co-cultivation of three rhizogenic Agrobacterium strains (Arqua1, LMG 63 and MAFF210266) with four Escallonia species (E. illinita, E. myrtoidea, E. rosea, and E. rubra), resulted in hairy roots production with a varying efficiency. Co-cultivation of E. rubra with MAFF210266, and E. myrtoidea with LMG63 did not yield hairy roots, while co-cultivation of E. rubra leaves with LMG63 was most successful for hairy root production (up to 80.6%). In addition, the efficiency of hairy root induction depended on the explant type (leaves or nodal sections). The presence of inserted rol-genes and aux-genes in hairy roots was molecularly confirmed using qPCR. Few shoots regenerated from hairy roots, but regeneration needs to be optimized for efficient implementation of rol-genes introgression in Escallonia breeding. Key Message: This research provides a protocol for the production of hairy roots with rol-genes inserted after co-cultivation of several species of Escallonia with rhizogenic Agrobacterium strains

Prestellar grain-surface origins of deuterated methanol in comet 67P/Churyumov-Gerasimenko

Deuterated methanol is one of the most robust windows astrochemists have on the individual chemical reactions forming deuterium-bearing molecules and the physicochemical history of the regions where they reside. The first-time detection of mono- and di-deuterated methanol in a cometary coma is presented for comet 67P/Churyumov-Gerasimenko using Rosetta-ROSINA data. D-methanol (CH3OD and CH2DOH combined) and D2-methanol (CH2DOD and CHD2OH combined) have an abundance of 5.5+/-0.46 and 0.00069+/-0.00014 per cent relative to normal methanol. The data span a methanol deuteration fraction (D/H ratio) in the 0.71-6.6 per cent range, accounting for statistical corrections for the location of D in the molecule and including statistical error propagation in the ROSINA measurements. It is argued that cometary CH2DOH forms from CO hydrogenation to CH3OH and subsequent H-D substitution reactions in CH3-R. CHD2OH is likely produced from deuterated formaldehyde. Meanwhile, CH3OD and CH2DOD, could form via H-D exchange reactions in OH-R in the presence of deuterated water ice. Methanol formation and deuteration is argued to occur at the same epoch as D2O formation from HDO, with formation of mono-deuterated water, hydrogen sulfide, and ammonia occurring prior to that. The cometary D-methanol/methanol ratio is demonstrated to agree most closely with that in prestellar cores and low-mass protostellar regions. The results suggest that cometary methanol stems from the innate cold (10-20 K) prestellar core that birthed our Solar System. Cometary volatiles individually reflect the evolutionary phases of star formation from cloud to core to protostar.Comment: Accepted for publication in MNRAS; 29 pages, 8 figures, 4 table

Characterization of the gaseous spacecraft environment of Rosetta by ROSINA

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90700/1/AIAA-2011-3822-983.pd