1,711 research outputs found
Regulation and Identity of Florigen: Flowering Locus T Moves Center Stage
The transition from vegetative to reproductive growth is controlled by day length in many plant species. Day length is perceived in leaves and induces a systemic signal, called florigen, that moves through the phloem to the shoot apex. At the shoot apical meristem (SAM), florigen causes changes in gene expression that reprogram the SAM to form flowers instead of leaves. Analysis of flowering of Arabidopsis thaliana placed the CONSTANS/FLOWERING LOCUS T (CO/FT) module at the core of a pathway that promotes flowering in response to changes in day length. We describe progress in defining the molecular mechanisms that activate this module in response to changing day length and the increasing evidence that FT protein is a major component of florigen. Finally, we discuss conservation of FT function in other species and how variation in its regulation could generate different flowering behaviors
Competence to Flower: Age-Controlled Sensitivity to Environmental Cues.
miR156 and SPL transcription factors play various roles in conferring competence to flower in plants
Mastery Learning: Improving the Model
In this paper, we report on developments in the Mastery Learning (ML) curriculum and assessment model that has been successfully implemented in a metropolitan university for teaching first-year mathematics. Initial responses to ML were positive; however, we ask whether the nature of the ML tests encourages a focus on shallow learning of procedures, and whether the structure of the assessment regime provides sufficient motivation for learning more complex problem solving. We analysed assessment data, as well as student reports and survey responses in an attempt to answer these questions
The Influence of in-medium NN cross-sections, symmetry potential and impact parameter on the isospin observables
We explore the influence of in-medium nucleon-nucleon cross section, symmetry
potential and impact parameter on isospin sensitive observables in
intermediate-energy heavy-ion collisions with the ImQMD05 code, a modified
version of Quantum Molecular Dynamics model. At incident velocities above the
Fermi velocity, we find that the density dependence of symmetry potential plays
a more important role on the double neutron to proton ratio and the
isospin transport ratio than the in-medium nucleon-nucleon cross
sections, provided that the latter are constrained to a fixed total NN
collision rate. We also explore both and as a function of the
impact parameter. Since the copious production of intermediate mass fragments
is a distinguishing feature of intermediate-energy heavy-ion collisions, we
examine the isospin transport ratios constructed from different groups of
fragments. We find that the values of the isospin transport ratios for
projectile rapidity fragments with are greater than those constructed
from the entire projectile rapidity source. We believe experimental
investigations of this phenomenon can be performed. These may provide
significant tests of fragmentation time scales predicted by ImQMD calculations.Comment: 24 pages, 9 figures, to be published in Phys. Rev.
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