7,089 research outputs found
Learning Design: reflections on a snapshot of the current landscape
The mounting wealth of open and readily available information and the swift evolution of social, mobile and creative technologies warrant a re-conceptualisation of the role of educators: from providers of knowledge to designers of learning. This need is being addressed by a growing trend of research in Learning Design. Responding to this trend, the Art and Science of Learning Design workshop brought together leading voices in the field and provided a forum for discussing its key issues. It focused on three thematic axes: practices and methods, tools and resources, and theoretical frameworks. This paper reviews some definitions of Learning Design and then summarises the main contributions to the workshop. Drawing upon these, we identify three key challenges for Learning Design that suggest directions for future research
Effects of pore modification on the templating of guest molecules in a 2D honeycomb network
This work was supported by the UK Engineering Physical Sciences Research Council (EPRSC) and the EU.1,7-Diadamantanethioperylene-3,4:9,10-tetracarboxylic diimide, (Ad-S)(2)-PTCDI, adsorbed on Au (111) from solution was investigated by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). (Ad-S)(2)-PTCDI forms a well-ordered monolayer whose structure is described by a (2 root 63 x root 19) R19.1 degrees chiral unit cell containing four molecules. Codeposition of (Ad-S)(2)-PTCDI with 1,3,5-triazine-2,4,6-triamine (melamine) yields a honeycomb network whose (7 root 3 x 7 root 3)R30 degrees unit cell is identical to the unsubstituted PTCDI/melamine analogue. The effect of the adamantyl thioether moieties on the adsorption of guest molecules is investigated using adamantane thiol and C-60. While the thioether units do not affect the packing of adamantane thiol molecules a pronounced influence is seen in the case of fullerene. Pore modification involving different combinations of enantiomers of (Ad-S)(2)-PTCDI give rise to distinctly different arrangements of C-60 molecules. The diversity of patterns is further increased by the presence of unsubstituted PTCDI molecules.PostprintPeer reviewe
alpha-nucleus potentials for the neutron-deficient p nuclei
alpha-nucleus potentials are one important ingredient for the understanding
of the nucleosynthesis of heavy neutron-deficient p nuclei in the astrophysical
gamma-process where these p nuclei are produced by a series of (gamma,n),
(gamma,p), and (gamma,alpha) reactions. I present an improved alpha-nucleus
potential at the astrophysically relevant sub-Coulomb energies which is derived
from the analysis of alpha decay data and from a previously established
systematic behavior of double-folding potentials.Comment: 6 pages, 3 figures, accepted for publication in Phys. Rev.
Radii and Binding Energies of Nuclei in the Alpha-Cluster Model
The alpha-cluster model is based on two assumptions that the proton-neutron
pair interactions are responsible for adherence between alpha-clusters and that
the NN-interaction in the alpha-clusters is isospin independent. It allows one
to estimate the Coulomb energy and the short range inter-cluster bond energy in
dependence on the number of clusters. The charge radii are calculated on the
number of alpha-clusters too. Unlike the Weizsacker formula in this model the
binding energies of alpha-clusters and excess neutrons are estimated
separately. The calculated values are in a good agreement with the experimental
data.Comment: Latex2e 2.09, 13 pages, 4 figure
Folding model analysis of alpha radioactivity
Radioactive decay of nuclei via emission of particles has been
studied theoretically in the framework of a superasymmetric fission model using
the double folding (DF) procedure for obtaining the -nucleus
interaction potential. The DF nuclear potential has been obtained by folding in
the density distribution functions of the nucleus and the daughter
nucleus with a realistic effective interaction. The M3Y effective interaction
has been used for calculating the nuclear interaction potential which has been
supplemented by a zero-range pseudo-potential for exchange along with the
density dependence. The nuclear microscopic -nucleus potential thus
obtained has been used along with the Coulomb interaction potential to
calculate the action integral within the WKB approximation. This subsequently
yields microscopic calculations for the half lives of decays of
nuclei. The density dependence and the exchange effects have not been found to
be very significant. These calculations provide reasonable estimates for the
lifetimes of radioactivity of nuclei.Comment: 7 pages including 1 figur
Characterization of Knots and Links Arising From Site-specific Recombination on Twist Knots
We develop a model characterizing all possible knots and links arising from
recombination starting with a twist knot substrate, extending previous work of
Buck and Flapan. We show that all knot or link products fall into three
well-understood families of knots and links, and prove that given a positive
integer , the number of product knots and links with minimal crossing number
equal to grows proportionally to . In the (common) case of twist knot
substrates whose products have minimal crossing number one more than the
substrate, we prove that the types of products are tightly prescribed. Finally,
we give two simple examples to illustrate how this model can help determine
previously uncharacterized experimental data.Comment: 32 pages, 7 tables, 27 figures, revised: figures re-arranged, and
minor corrections. To appear in Journal of Physics
Optimal shapes of compact strings
Optimal geometrical arrangements, such as the stacking of atoms, are of
relevance in diverse disciplines. A classic problem is the determination of the
optimal arrangement of spheres in three dimensions in order to achieve the
highest packing fraction; only recently has it been proved that the answer for
infinite systems is a face-centred-cubic lattice. This simply stated problem
has had a profound impact in many areas, ranging from the crystallization and
melting of atomic systems, to optimal packing of objects and subdivision of
space. Here we study an analogous problem--that of determining the optimal
shapes of closely packed compact strings. This problem is a mathematical
idealization of situations commonly encountered in biology, chemistry and
physics, involving the optimal structure of folded polymeric chains. We find
that, in cases where boundary effects are not dominant, helices with a
particular pitch-radius ratio are selected. Interestingly, the same geometry is
observed in helices in naturally-occurring proteins.Comment: 8 pages, 3 composite ps figure
Experiences from using Action Learning Groups to develop Sustainable Farming Systems for Central Queensland
Farmer-based action learning groups have been used to conduct on-farm research in the “Sustainable Farming Systems for Central Queensland” project, with the aim of developing profitable and sustainable farming systems and having them adopted. Group facilitators and technical staff help guide the groups using the action learning process. This guidance, and the use of adult learning principles has ensured that groups remain focussed on achieving their goals and that profitable and sustainable farming systems are adopted. This paper details the experiences gained in facilitating action learning at key points in group development, including group formation, planning and implementing research and evaluation. Key factors needed for effectively using action learning to develop profitable and sustainable farming systems and improve adoption are identified and discusse
Challenges of on-farm research - insights from the Central Queensland farming systems experience
The “Sustainable Farming Systems for Central Queensland” project aims to develop profitable and sustainable farming systems in central Queensland and to have these systems widely adopted. Farmer-based groups are involved in on-farm research into system components at ten locations in central Queensland, with project staff facilitating and guiding this research and system development.
At the project’s inception, on-farm research was seen as a means of integrating Research, Development and Extension (R,D&E), resulting in research outcomes relevant to producers therefore improving the rate of adoption. Although the use of on-farm research has produced locally relevant system components that are being adopted, using this methodology has not been without its challenges. This paper describes the experiences of the authors in implementing on-farm research, detailing the challenges faced and methods used to deal with them
State-to-State Differential and Relative Integral Cross Sections for Rotationally Inelastic Scattering of H2O by Hydrogen
State-to-state differential cross sections (DCSs) for rotationally inelastic
scattering of H2O by H2 have been measured at 71.2 meV (574 cm-1) and 44.8 meV
(361 cm-1) collision energy using crossed molecular beams combined with
velocity map imaging. A molecular beam containing variable compositions of the
(J = 0, 1, 2) rotational states of hydrogen collides with a molecular beam of
argon seeded with water vapor that is cooled by supersonic expansion to its
lowest para or ortho rotational levels (JKaKc= 000 and 101, respectively).
Angular speed distributions of fully specified rotationally excited final
states are obtained using velocity map imaging. Relative integral cross
sections are obtained by integrating the DCSs taken with the same experimental
conditions. Experimental state-specific DCSs are compared with predictions from
fully quantum scattering calculations on the most complete H2O-H2 potential
energy surface. Comparison of relative total cross sections and state-specific
DCSs show excellent agreement with theory in almost all detailsComment: 46 page
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