3,397 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
Quasiparticle Resonances in the BCS Approach
We present a simple method for calculating the energies and the widths of
quasiparticle resonant states. The method is based on BCS equations solved in
the Berggren representation. In this representation the quasiparticle
resonances are associated to the Gamow states of the mean field. The method is
illustrated for the case of neutron-rich nuclei O and Ni. It
is shown that the contribution of the continuum coupling to the pairing
correlations is small and largely dominated by a few resonant states close to
the continuum threshold.Comment: 14 pages, 2 figure
Gamow Shell Model Description of Neutron-Rich Nuclei
This work presents the first continuum shell-model study of weakly bound
neutron-rich nuclei involving multiconfiguration mixing. For the
single-particle basis, the complex-energy Berggren ensemble representing the
bound single-particle states, narrow resonances, and the non-resonant continuum
background is taken. Our shell-model Hamiltonian consists of a one-body finite
potential and a zero-range residual two-body interaction. The systems with two
valence neutrons are considered. The Gamow shell model, which is a
straightforward extension of the traditional shell model, is shown to be an
excellent tool for the microscopic description of weakly bound systems. It is
demonstrated that the residual interaction coupling to the particle continuum
is important; in some cases, it can give rise to the binding of a nucleus.Comment: 4 pages, More realistic s.p. energies used than in the precedent
versio
Temperature dependent BCS equations with continuum coupling
The temperature dependent BCS equations are modified in order to include the
contribution of the continuum single particle states. The influence of the
continuum upon the critical temperature corresponding to the phase transition
from a superfluid to a normal state and upon the behaviour of the excitation
energy and of the entropy is discussed.Comment: 9 pages, 3 figures, to appear in Phys. Rev.
Complex 2D Matrix Model and Geometrical Map on Complex-Nc Plane
We study the parameter dependence of the internal structure of resonance
states by formulating Complex two-dimensional (2D) Matrix Model, where the two
dimensions represent two-levels of resonances. We calculate a critical value of
the parameter at which "nature transition" with character exchange occurs
between two resonance states, from the viewpoint of geometry on
complex-parameter space. Such critical value is useful to know the internal
structure of resonance states with variation of the parameter in the system. We
apply the model to analyze the internal structure of hadrons with variation of
the color number Nc from infinity to a realistic value 3. By regarding 1/Nc as
the variable parameter in our model, we calculate a critical color number of
nature transition between hadronic states in terms of quark-antiquark pair and
mesonic molecule as exotics from the geometry on complex-Nc plane. For the
large-Nc effective theory, we employ the chiral Lagrangian induced by
holographic QCD with D4/D8/D8-bar multi-D brane system in the type IIA
superstring theory.Comment: 14 pages, 8 figures, 1 table, figures and appendixes added, results
unchange
Drift Correction for Scanning-Electron Microscopy by
Scanning electron micrographs at high magnification (100,000x and up) are distorted by motion of the sample during image acquisition, a phenomenon called drift. We propose a method for correcting drift distortion in images obtained on scanning electron and other scanned-beam microscopes by registering a series of images to create a drift-free composite. We develop a drift-distortion model for linear drift and use it as a basis for an affine correction between images in the sequence. The performance of our correction method is evaluated with simulated datasets and real datasets taken on both scanning electron and scanning helium-ion microscopes; we compare performance against translation only correction. In simulation, we exhibit a 12.5 dB improvement in SNR of our drift-corrected composite compared to a non-aligned composite, and a 3 dB improvement over translation correction. A more modest 0.
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