10,482 research outputs found
Identification and expression analysis of CBF/DREB1 and COR15 genes in mutants of Brassica oleracea var. botrytis with enhanced proline production and frost resistance.
Frost resistant mutants of Brassica oleracea var. botrytis were investigated for the presence of CBF/DREB1 and COR15a gene products and induced frost resistance. Total RNA of clones was isolated after 3 h, 6 h, 24 h and 14 d acclimation at 4 °C and proteins and free proline were isolated after 14 d acclimation. cDNA was produced using RT-PCR and the first CBF gene in B. oleracea detected and did quantify. Through SDS-PAGE and Western blotting, the COR15a protein was detected for the first time in B. oleracea. The results confirmed the first report of the presence of BoCBF/DREB1 in B. oleracea and this only appeared under cold acclimation. The sequence analysis of predicted amino acids revealed a very high homology (90%) with CBF sequences of other Brassica species (BnCBF5/DREB1, BrDREB1 and BjDREB1B) and homology reduced to 67% when compared to plants other than Brassicas. BoCBF/DREB1 transcript levels increased up to 24 h acclimation and then declined. Some mutants showed BoCBF/DREB1 expression at 3 h while others only after 6 h and 24 h acclimation. The genotypes showed positive significant correlation between BoCBF/DREB1 expression and frost resistance (R(2) = 0.9343). The proline level under acclimation increased about 8 fold and demonstrated positive and significant correlation with BoCBF/DREB1 expression. Proline also showed positive and significant correlation with frost resistance under cold acclimation but very not under non-acclimation. All clones were positive for COR15a protein after 14 d cold acclimation and expression correlated with frost resistance. Under non-acclimation COR15a was constitutively expressed in 3 mutants
The genealogy of judgement: towards a deep history of academic freedom
The classical conception of academic freedom associated with Wilhelm von Humboldt and the rise of the modern university has a quite specific cultural foundation that centres on the controversial mental faculty of 'judgement'. This article traces the roots of 'judgement' back to the Protestant Reformation, through its heyday as the signature feature of German idealism, and to its gradual loss of salience as both a philosophical and a psychological concept. This trajectory has been accompanied by a general shrinking in the scope of academic freedom from the promulgation of world-views to the offering of expert opinion
Neutrino-Accelerated Hot Hydrogen Burning
We examine the effects of significant electron anti-neutrino fluxes on
hydrogen burning. Specifically, we find that the bottleneck weak nuclear
reactions in the traditional pp-chain and the hot CNO cycle can be accelerated
by anti-neutrino capture, increasing the energy generation rate. We also
discuss how anti-neutrino capture reactions can alter the conditions for break
out into the rp-process. We speculate on the impact of these considerations for
the evolution and dynamics of collapsing very- and super- massive compact
objects.Comment: 14 pages, 6 figures, submitted to ApJ; minor content chang
Neutrino scattering and flavor transformation in supernovae
We argue that the small fraction of neutrinos that undergo direction-changing
scattering outside of the neutrinosphere could have significant influence on
neutrino flavor transformation in core-collapse supernova environments. We show
that the standard treatment for collective neutrino flavor transformation is
adequate at late times, but could be inadequate in the crucial shock
revival/explosion epoch of core-collapse supernovae, where the potentials that
govern neutrino flavor evolution are affected by the scattered neutrinos.
Taking account of this effect, and the way it couples to entropy and
composition, will require a new paradigm in supernova modeling.Comment: 5 pages, 3 figure
Halo Modification of a Supernova Neutronization Neutrino Burst
We give the first self-consistent calculation of the effect of the scattered
neutrino halo on flavor evolution in supernovae. Our example case is an O-Ne-Mg
core collapse supernova neutronization neutrino burst. We find that the
addition of the halo neutrinos produces qualitative and quantitative changes in
the final flavor states of neutrinos. We also find that the halo neutrinos
produce a novel distortion of the neutrino flavor swap. Our results provide
strong motivation for tackling the full multidimensional and
composition-dependent aspects of this problem in the future.Comment: 14 pages, 13 figures, 1 tabl
Presupernova collapse models with improved weak-interaction rates
Improved values for stellar weak interaction rates have been recently
calculated based upon a large shell model diagonalization. Using these new
rates (for both beta decay and electron capture), we have examined the
presupernova evolution of massive stars in the range 15-40 Msun. Comparing our
new models with a standard set of presupernova models by Woosley and Weaver, we
find significantly larger values for the electron-to-baryon ratio Ye at the
onset of collapse and iron core masses reduced by approximately 0.1 Msun. The
inclusion of beta-decay accounts for roughly half of the revisions, while the
other half is a consequence of the improved nuclear physics. These changes will
have important consequences for nucleosynthesis and the supernova explosion
mechanism.Comment: 4 pages, 2 figure
Becoming a teacher: conceptual and practice development in the learning and skills sector
Drawing on a mixed-methods study of in-service learning and skills sector (LSS) trainees, comprising beginning- and end-of-year surveys and six longitudinal case studies together with literature on traineesâ development in the LSS, schools and higher education sectors, conceptual and practice development continua are proposed. Conceptions become more multi-dimensional and increasingly link teaching and learning whilst initial concern with the practicalities of teaching is followed by recognition of learnersâ needs. Next, greater emphasis is placed on learner autonomy and catering for individualsâ needs and finally assessment and evaluation is used systematically to shape practice. The continua offer an understanding of the subtleties and complexities of trainee development allowing
for different starting and end points and accommodating varied work contexts. I argue that this provides a more adequate basis for the development of initial teacher education (ITE) than the prescriptive approach embedded within recent LSS ITE policy reforms
Twist and writhe dynamics of stiff filaments
This letter considers the dynamics of a stiff filament, in particular the
coupling of twist and bend via writhe. The time dependence of the writhe of a
filament is for a linear filament and for a curved filament. Simulations are used to study the relative
importance of crankshaft motion and tube like motion in twist dynamics.
Fuller's theorem, and its relation with the Berry phase, is reconsidered for
open filamentsComment: 7 Pages with 2 figure
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