16,781 research outputs found
Case studies to enhance online student evaluation: Bond University – Surveying students online to improve learning and teaching
One of the most sensible ways of improving learning and teaching is to ask the students for feedback. At the end of each teaching period (i.e. semester or term) all universities and many schools survey their students. Usually these surveys are managed online. Questions ask for student perceptions about teaching, assessment and workload. The survey administrators report four common problems
Multiparticle States and the Hadron Spectrum on the Lattice
The Clebsch-Gordan decomposition is calculated for direct products of the
irreducible representations of the cubic space group. These results are used to
identify multiparticle states which appear in the hadron spectrum on the
lattice. Consideration of the cubic space group indicates how combinations of
both zero momentum and non-zero momentum multiparticle states contribute to the
spectrum.Comment: v2) Little groups for lattice momenta corrected. Includes a more
consistent labeling scheme. (13 pages
The Effect of Resistivity on the Nonlinear Stage of the Magnetorotational Instability in Accretion Disks
We present three-dimensional magnetohydrodynamic simulations of the nonlinear
evolution of the magnetorotational instability (MRI) with a non-zero Ohmic
resistivity. The properties of the saturated state depend on the initial
magnetic field configuration. In simulations with an initial uniform vertical
field, the MRI is able to support angular momentum transport even for large
resistivities through the quasi-periodic generation of axisymmetric radial
channel solutions rather than through the maintenance of anisotropic
turbulence. Simulations with zero net flux show that the angular momentum
transport and the amplitude of magnetic energy after saturation are
significantly reduced by finite resistivity, even at levels where the linear
modes are only slightly affected. This occurs at magnetic Reynolds numbers
expected in low, cool states of dwarf novae, these results suggest that finite
resistivity may account for the low and high angular momentum transport rates
inferred for these systems.Comment: 8 figures, accepted for publication in Ap
An improved perturbation approach to the 2D Edwards polymer -- corrections to scaling
We present the results of a new perturbation calculation in polymer
statistics which starts from a ground state that already correctly predicts the
long chain length behaviour of the mean square end--to--end distance , namely the solution to the 2~dimensional~(2D) Edwards model.
The thus calculated is shown to be convergent in ,
the number of steps in the chain, in contrast to previous methods which start
from the free random walk solution. This allows us to calculate a new value for
the leading correction--to--scaling exponent~. Writing , where in 2D,
our result shows that . This value is also supported by an
analysis of 2D self--avoiding walks on the {\em continuum}.Comment: 17 Pages of Revtex. No figures. Submitted to J. Phys.
Non-Markovian Dynamics and Entanglement of Two-level Atoms in a Common Field
We derive the stochastic equations and consider the non-Markovian dynamics of
a system of multiple two-level atoms in a common quantum field. We make only
the dipole approximation for the atoms and assume weak atom-field interactions.
From these assumptions we use a combination of non-secular open- and
closed-system perturbation theory, and we abstain from any additional
approximation schemes. These more accurate solutions are necessary to explore
several regimes: in particular, near-resonance dynamics and low-temperature
behavior. In detuned atomic systems, small variations in the system energy
levels engender timescales which, in general, cannot be safely ignored, as
would be the case in the rotating-wave approximation (RWA). More problematic
are the second-order solutions, which, as has been recently pointed out, cannot
be accurately calculated using any second-order perturbative master equation,
whether RWA, Born-Markov, Redfield, etc.. This latter problem, which applies to
all perturbative open-system master equations, has a profound effect upon
calculation of entanglement at low temperatures. We find that even at zero
temperature all initial states will undergo finite-time disentanglement
(sometimes termed "sudden death"), in contrast to previous work. We also use
our solution, without invoking RWA, to characterize the necessary conditions
for Dickie subradiance at finite temperature. We find that the subradiant
states fall into two categories at finite temperature: one that is temperature
independent and one that acquires temperature dependence. With the RWA there is
no temperature dependence in any case.Comment: 17 pages, 13 figures, v2 updated references, v3 clarified results and
corrected renormalization, v4 further clarified results and new Fig. 8-1
Behavioural assessment of dental pain in captive Malayan sun bears (Helarctos malayanus)
Magnetic control assembly qualification model
Fabrication and testing of the magnetic control assembly (MCA) are summarized. The MCA was designed as an add-on unit for certain existing components of the Nimbus and ERTS attitude control system. The MCA system consists of three orthogonal electromagnets; a magnetometer probe capable of sensing external fields in the X, Y, and Z axes; and the control electronics. An operational description of the system is given along with all major drawings and photographs. Manufacturing and inspection procedures are outlined and a chronological list of events is included with the fabrication summary
The Holocaust in Eastern Europe: sources, memory, politics
On 16 March 2021, the Institute for Polish–Jewish Studies, the Department of Hebrew and Jewish Studies at University College London (UCL), and The Wiener Holocaust Library convened an online symposium in honour of Professor Antony Polonsky on the occasion of his eightieth birthday. Entitled “The Holocaust in Eastern Europe: Sources, Memory, Politics”, the symposium brought together established and junior scholars researching the Holocaust in Eastern Europe and provided a timely overview of the state of knowledge. The presentations from the symposium can now be viewed online at The Wiener Holocaust Library’s YouTube channel at this link: http://bit.ly/Polonsky21
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