Supersymmetric Non-abelian DBI Equations from Open Pure Spinor Superstring

The BRST invariance of the open pure spinor superstring is examined in the presence of background superfields on a Dp-brane. We note that the background superfields introduced in this paper depend on boundary fermions. The BRST invariance leads to supersymmetric Dirac-Born-Infeld (DBI) equations for background superfields depending on boundary fermions as well as boundary conditions on spacetime coordinates. After quantizing boundary fermions, background superfields are promoted to non-abelian ones. As a result, we obtain the supersymmetric non-abelian DBI equations from the supersymmetric DBI equations depending on boundary fermions. It is shown that these non-abelian DBI equations reduce to the super-Yang-Mills equations in the limit alpha' -> 0. We also show the nilpotency of the BRST transformation of boundary fermions.Comment: 19 page

Parallel evolution of dominant pistil-side self-incompatibility suppressors in Arabidopsis

Selfing is a frequent evolutionary trend in angiosperms, and is a suitable model for studying the recurrent patterns underlying adaptive evolution. Many plants avoid self-fertilization by physiological processes referred to as self-incompatibility (SI). In the Brassicaceae, direct and specific interactions between the male ligand SP11/SCR and the female receptor kinase SRK are required for the SI response. Although Arabidopsis thaliana acquired autogamy through loss of these genes, molecular evolution contributed to the spread of self-compatibility alleles requires further investigation. We show here that in this species, dominant SRK silencing genes have evolved at least twice. Different inverted repeat sequences were found in the relic SRK region of the Col-0 and C24 strains. Both types of inverted repeats suppress the functional SRK sequence in a dominant fashion with different target specificities. It is possible that these dominant suppressors of SI contributed to the rapid fixation of self-compatibility in A. thaliana

Transcriptome map of plant mitochondria reveals islands of unexpected transcribed regions

<p>Abstract</p> <p>Background</p> <p>Plant mitochondria contain a relatively large amount of genetic information, suggesting that their functional regulation may not be as straightforward as that of metazoans. We used a genomic tiling array to draw a transcriptomic atlas of <it>Oryza sativa japonica </it>(rice) mitochondria, which was predicted to be approximately 490-kb long.</p> <p>Results</p> <p>Whereas statistical analysis verified the transcription of all previously known functional genes such as the ones related to oxidative phosphorylation, a similar extent of RNA expression was frequently observed in the inter-genic regions where none of the previously annotated genes are located. The newly identified open reading frames (ORFs) predicted in these transcribed inter-genic regions were generally not conserved among flowering plant species, suggesting that these ORFs did not play a role in mitochondrial principal functions. We also identified two partial fragments of retrotransposon sequences as being transcribed in rice mitochondria.</p> <p>Conclusion</p> <p>The present study indicated the previously unexpected complexity of plant mitochondrial RNA metabolism. Our transcriptomic data (<it>Oryza sativa </it>Mitochondrial rna Expression Server: OsMES) is publicly accessible at [<url>http://bioinf.mind.meiji.ac.jp/cgi-bin/gbrowse/OsMes/#search</url>].</p

The VLT-FLAMES Tarantula Survey XVIII. Classifications and radial velocities of the B-type stars

We present spectral classifications for 438 B-type stars observed as part of the VLT-FLAMES Tarantula Survey (VFTS) in the 30 Doradus region of the Large Magellanic Cloud. Radial velocities are provided for 307 apparently single stars, and for 99 targets with radial-velocity variations which are consistent with them being spectroscopic binaries. We investigate the spatial distribution of the radial velocities across the 30 Dor region, and use the results to identify candidate runaway stars. Excluding potential runaways and members of two older clusters in the survey region (SL 639 and Hodge 301), we determine a systemic velocity for 30 Dor of 271.6 ± 12.2 kms-1 from 273 presumed single stars. Employing a 3σ criterion we identify nine candidate runaway stars (2.9% of the single stars with radial-velocity estimates). The projected rotational velocities of the candidate runaways appear to be significantly different to those of the full B-type sample, with a strong preference for either large (≥345 kms-1) or small (≤65 kms-1) rotational velocities. Of the candidate runaways, VFTS 358 (classified B0.5: V) has the largest differential radial velocity (−106.9 ± 16.2 kms-1), and a preliminary atmospheric analysis finds a significantly enriched nitrogen abundance of 12 + log (N/H) ≳ 8.5. Combined with a large rotational velocity (ve sin i = 345 ± 22 kms-1), this is suggestive of past binary interaction for this star

Interactions between a top order predator and exotic mesopredators in the Australian rangelands

Extent: 15p.An increase in mesopredators caused by the removal of top-order predators can have significant implications for threatened wildlife. Recent evidence suggests that Australia’s top-order predator, the dingo, may suppress the introduced cat and red fox. We tested this relationship by reintroducing 7 foxes and 6 feral cats into a 37 km2 fenced paddock in arid South Australia inhabited by a male and female dingo. GPS datalogger collars recorded locations of all experimental animals every 2 hours. Interactions between species, mortality rates, and postmortems were used to determine the mechanisms of any suppression. Dingoes killed all 7 foxes within 17 days of their introduction and no pre-death interactions were recorded. All 6 feral cats died between 20 and 103 days after release and dingoes were implicated in the deaths of at least 3 cats. Dingoes typically stayed with fox and cat carcasses for several hours after death and/or returned several times in ensuing days. There was no evidence of intraguild predation, interference competition was the dominant mechanism of suppression. Our results support anecdotal evidence that dingoes may suppress exotic mesopredators, particularly foxes. We outline further research required to determine if this suppression translates into a net benefit for threatened prey species.Katherine E. Moseby, Heather Neilly, John L. Read, and Helen A. Cris

Preparation and thermal stability of oxynitride perovskite solid solution Sr1-xLaxTa1-xTixO2N

The thermal stability of oxynitride perovskites is very important for the fabrication of their dense ceramics. In this study, a solid solution of the oxynitride perovskite Sr1-xLaxTa1-xTixO2N was prepared via the ammonia nitridation of oxide precursors. The oxynitrides products obtained at x = 0.7 had tetragonal and triclinic perovskite-type structures, respectively. A neutron diffraction study on the oxynitride product obtained at x = 0.2 indicated that this tetragonal perovskite had a cis-type anion distribution similarly to SrTaO2N. The tetragonal perovskite released a part of nitrogen at approximately 1000 degrees C in a nitrogen atmosphere while maintaining the perovskite structure at least to 1450 degrees C. The oxynitride perovskites at x >= 0.5 gradually decomposed to a mixture of LaTiO2N, LaTiO3, La(OH)(3), La2O3, TiN and TaO above 1100 degrees C