Effect of angular opening on the dynamics of relativistic hydro jets

Context. Relativistic jets emerging from AGN cores transfer energy from the core to their surrounding ISM/IGM. Because jets are observed to have finite opening angles, one needs to quantify the role of conical versus cylindrical jet propagation in this energy transfer. Aims. We use FR-II AGN jets parameter with finite opening angles. We study the effect of the variation of the opening angle on the dynamics and energy transfer of the jet. We also point out how the characteristics of this external medium, such as its density profile, play a role in the dynamics. Methods. This study exploits our parallel AMR code MPI-AMRVAC with its special relativistic hydrodynamic model, incorporating an equation of state with varying effective polytropic index. We studied mildly under-dense jets up to opening angles of 10 degrees, at Lorentz factors of about 10, inspired by observations. Instantaneous quantification of the various ISM volumes and their energy content allows one to quantify the role of mixing versus shock-heated cocoon regions over the time intervals. Results. We show that a wider opening angle jet results in a faster deceleration of the jet and leads to a wider cocoon dominated by Kelvin-Helmholtz and Rayleigh-Taylor instabilities. The energy transfer mainly occurs in the shocked ISM region by both the frontal bow shock and cocoon-traversing shock waves, in a roughly 3 to 1 ratio to the energy transfer of the mixing zone, for a 5 degree opening angle jet. A rarefaction wave induces a dynamically formed layered structure of the jet beam. Conclusions. Finite opening angle jets can efficiently transfer significant fractions (25 % up to 70 %) of their injected energy over a growing region of shocked ISM matter. The role of the ISM stratification is prominent for determining the overall volume that is affected by relativistic jet injection

Nuclear fusions contribute to polyploidization of the gigantic nuclei in the chalazal endosperm of Arabidopsis

Somatic polyploidization is recognized as a means to increase gene expression levels in highly active metabolic cells. The most common mechanisms are endoreplication, endomitosis and cell fusion. In animals and plants the nuclei of multinucleate cells are usually prevented from fusing. Here, we report that the nuclei from the syncytial cyst of the chalazal endosperm of Arabidopsis thaliana (L.) Heynh. are polyploid with some intermediate ploidy levels that cannot be attributed to endoreplication, suggesting nuclear fusion. Analysis of isolated nuclei, together with fluorescent in situ hybridization (FISH), revealed that nuclei from the chalazal endosperm are two or three times bigger than the nuclei from the peripheral endosperm and have a corresponding increase in ploidy. Together with the consistent observation of adjoined nuclei, we propose that nuclear fusion contributes, at least in part, to the process of polyploidization in the chalazal endosperm. Confocal analysis of intact seeds further suggested that free nuclei from the peripheral endosperm get incorporated into the chalazal cyst and likely participate in nuclear fusion

Circular geodesics and thick tori around rotating boson stars

Accretion disks play an important role in the evolution of their relativistic inner compact objects. The emergence of a new generation of interferometers will allow to resolve these accretion disks and provide more information about the properties of the central gravitating object. Due to this instrumental leap forward it is crucial to investigate the accretion disk physics near various types of inner compact objects now to deduce later constraints on the central objects from observations. A possible candidate for the inner object is the boson star. Here, we will try to analyze the differences between accretion structures surrounding boson stars and black holes. We aim at analysing the physics of circular geodesics around boson stars and study simple thick accretion tori (so-called Polish doughnuts) in the vicinity of these stars. We realize a detailed study of the properties of circular geodesics around boson stars. We then perform a parameter study of thick tori with constant angular momentum surrounding boson stars. This is done using the boson star models computed by a code constructed with the spectral solver library KADATH. We demonstrate that all the circular stable orbits are bound. In the case of a constant angular momentum torus, a cusp in the torus surface exists only for boson stars with a strong gravitational scalar field. Moreover, for each inner radius of the disk, the allowed specific angular momentum values lie within a constrained range which depends on the boson star considered. We show that the accretion tori around boson stars have different characteristics than in the vicinity of a black hole. With future instruments it could be possible to use these differences to constrain the nature of compact objects.Comment: Accepted for publication in CQ

Analyses of the stress field in southeastern France from earthquake focal mechanisms

Due to the apparent deformation field heterogeneity, the stress regimes around the Provence block, from the fronts of the Massif Central and Alpine range up to the Ligurian Sea, were not well defined. To improve the understanding of the SE France stress field, we determine new earthquake focal mechanisms and we compute the present-day stress states by inversion of the 89 available focal mechanisms around the Provence domain, including the 17 new ones calculated in the current study. This study provides evidence of 6 different deformation domains around the Provence block with different tectonic regimes. On a regional scale, we identify three zones characterised by significantly different stress regimes: a western one affected by an extensional stress (normal faulting) regime, a southeastern one characterised by a compressional stress (reverse to strike-slip faulting) regime with NNW- to WNW-trending σ1 and a northeastern one, i.e., the Digne nappe front, marked by an NE-trending compression. Note that the Digne nappe back domain is controlled by an extensional regime that is deforming the western alpine core. This extensional regime could be a response to buoyancy forces related to the Alpine high topography. The stress regimes in the southeast of the Argentera Massif and around the Durance fault are consistent with a coherent NNW-trending σ1 that implies a left-lateral component of the active reverse oblique-slip of the Moyenne Durance Fault. In the Rhone Valley, an E-trending extension characterises the tectonic regime that implies a normal component of the present-day Nîmes fault displacement. This study provides evidence for short-scale variation of the stress states that reflect abrupt change in the boundary force influences on upper crustal fragments (blocks). These spatial stress changes around the Provence block result from the coeval influence of forces applied at both its extremities, i.e., in the north-east, the Alpine front push and in the southeast, the northward African plate drift. Besides these boundary forces, the influence of the mantle plume under the Massif Central can be superimposed along the western block boundary

PHO1 Exports Phosphate from the Chalazal Seed Coat to the Embryo in Developing Arabidopsis Seeds.

Seed production requires the transfer of nutrients from the maternal seed coat to the filial endosperm and embryo. Because seed coat and filial tissues are symplasmically isolated, nutrients arriving in the seed coat via the phloem must be exported to the apoplast before reaching the embryo. Proteins implicated in the transfer of inorganic phosphate (Pi) from the seed coat to the embryo are unknown despite seed P content being an important agronomic trait. Here we show that the Arabidopsis Pi exporters PHO1 and PHOH1 are expressed in the chalazal seed coat (CZSC) of developing seeds. PHO1 is additionally expressed in developing ovules. Phosphorus (P) content and Pi flux between the seed coat and embryo were analyzed in seeds from grafts between WT roots and scions from either pho1, phoh1, or the pho1 phoh1 double mutant. Whereas P content and distribution between the seed coat and embryo in fully mature dry seeds of these mutants are similar to the WT, at the mature green stage of seed development the seed coat of the pho1 and pho1 phoh1 mutants, but not of the phoh1 mutant, retains approximately 2-fold more P than its WT control. Expression of PHO1 under a CZSC-specific promoter complemented the seed P distribution phenotype of the pho1 phoh1 double mutant. CZSC-specific down-expression of PHO1 also recapitulated the seed P distribution phenotype of pho1. Together, these experiments show that PHO1 expression in the CZSC is important for the transfer of P from the seed coat to the embryo in developing seeds

Genomic Origin and Organization of the Allopolyploid Primula egaliksensis Investigated by in situ Hybridization

Background and Aims Earlier studies have suggested that the tetraploid Primula egaliksensis (2n = 40) originated from hybridization between the diploids P. mistassinica (2n = 18) and P. nutans (2n = 22), which were hypothesized to be the maternal and paternal parent, respectively. The present paper is aimed at verifying the hybrid nature of P. egaliksensis using cytogenetic tools, and to investigate the extent to which the parental genomes have undergone genomic reorganization. Methods Genomic in situ hybridization (GISH) and fluorescent in situ hybridization (FISH) with ribosomal DNA (rDNA) probes, together with sequencing of the internal transcribed spacer (ITS) region of the rDNA, were used to identify the origin of P. egaliksensis and to explore its genomic organization, particularly at rDNA loci. Key Results GISH showed that P. egaliksensis inherited all chromosomes from P. mistassinica and P. nutans and did not reveal major intergenomic rearrangements between the parental genomes (e.g. interchromosomal translocations). However, karyological comparisons and FISH experiments suggested small-scale rearrangements, particularly at rDNA sites. Primula egaliksensis lacked the ITS-bearing heterochromatic knobs characteristic of the maternal parent P. mistassinica and maintained only the rDNA loci of P. nutans. These results corroborated sequence data indicating that most ITS sequences of P. egaliksensis were of the paternal repeat type. Conclusions The lack of major rearrangements may be a consequence of the considerable genetic divergence between the putative parents, while the rapid elimination of the ITS repeats from the maternal progenitor may be explained by the subterminal location of ITS loci or a potential role of nucleolar dominance in chromosome stabilization. These small-scale rearrangements may be indicative of genome diploidization, but further investigations are needed to confirm this assumptio

Relativistic 3D jet simulations for the X-ray binary SS433

Context. Modern high resolution observations allow to view closer into the objects powering relativistic jets. This is especially the case for SS433, an X-ray binary from which a precessing jet is observed down to the sub-parsec scale. Aims. We want to study full 3D dynamics of relativistic jets associated with AGN or XRB. We study the precessing motion of a jet as a model for the jet associated with the XRB SS433. Our study of the jet dynamics in this system focuses on the sub-parsec scales. We investigate the impact of jet precession and the variation of the Lorentz factor of the injected matter on the general 3D jet dynamics and its energy transfer to the surrounding medium. We realize synthetic radio mapping of the data, to compare our results with observations. Methods. For our study we use the code MPI-AMRVAC with SRHD model of a baryonic jet. We use a AMR scheme and an inner time-dependent boundary prescription to inject the jets. Parameters extracted from observations were used. 3D jet realizations that match the SS433 jet are intercompared. We track the energy content, as deposited in different regions of the domain affected by the jet. Our code also follows a population of particles injected with the jet. This evolving energy spectrum of accelerated electrons, allows to obtain the radio emission from our simulation. Results. we obtain meaningful observations. We find increased energy transfer for a precessing jet compared to a standing jets. We obtain synthetic radio maps for all jets. Conclusions. The synthetic radio map matches best for a model using the canonical kinematic model. Overdense precessing jets experience significant deceleration in their propagation through the ISM, and while the overall jet is of helical shape. This argument show that the kinematic model for SS433 assuming ballistic propagation has to be corrected for this decelretaion.Comment: Accepted for publication in Astrophysic and Astronom

WP8 Modelling of topographic signal: GIS-BASED data base of potential earthquake sources identified in suitable kei-areas

GIS-based database of potential earthquake sources that were identified in key areas, such as the Provence, France, Po Plain, Italy, Outer Jura, Switzerland. The seismogenic source is defined as in Valensise and Pantosti (2001) following the scheme de-veloped in the framework of the EC project FAUST (Valensise et al., 2002)

Source parameters of the 11 June 1909, Lambesc (Provence, southeastern France) earthquake: a reappraisal based on macroseismic, seismological and geodetic observations

Destructive earthquakes are rare in France yet pose a sizable seismic hazard, especially when critical infrastructures are concerned. Only a few destructive events have occurred within the instrumental period, the most important being the 11 June 1909, Lambesc (Provence) earthquake. With a magnitude estimated at 6.2 [Rothé, 1942], the event was recorded by 30 observatories and produced intensity IX effects in the epicentral area, ~30 km north of Marseille. We collected 30 seismograms, leveling data and earthquake intensities to assess the magnitude and possibly the focal mechanism of this event. Following this multidisciplinary approach, we propose a source model where all relevant parameters are constrained by at least two of the input datasets. Our reappraisal of the seismological data yielded Mw 5.8-6.1 (6.0 preferred) and Ms 6.0, consistent with the magnitude from intensity data (Me 5.8) and with constraints derived from modeling of coseismic elevation changes. Hence, we found the Lambesc earthquake to have been somewhat smaller than previously reported. Our datasets also constrain the geometry and kinematics of faulting, suggesting that the earthquake was generated by reverse-right lateral slip on a WNW-striking, steeply north-dipping fault beneath the western part of the Trévaresse fold. This result suggests that the fold, located in front of the Lubéron thrust, plays a significant role in the region’s recent tectonic evolution. The sense of slip obtained for the 1909 rupture also agrees with the regional stress field obtained from earthquake focal mechanisms and microtectonic data as well as recent GPS data