708 research outputs found
Handbook for Learning-centred evaluation of Computer-facilitated learning projects in higher education
This handbook supports a project funded by the Australian Government Committee for University Teaching and Staff Development (CUTSD). The amended project title is “Staff Development in Evaluation of Technology-based Teaching Development Projects: An Action Inquiry Approach”.
The project is hosted by Murdoch University on behalf of the Australasian Society for Computers in Learning in Tertiary Education (ASCILITE), as a consortium of 11 universities.
The rationale of the project is to guide a group of university staff through the evaluation of a Computer-facilitated Learning (CFL1) project by a process of action inquiry and mentoring, supported by the practical and theoretical material contained in this handbook
Wetting and contact-line effects for spherical and cylindrical droplets on graphene layers: A comparative molecular-dynamics investigation
In Molecular Dynamics (MD) simulations, interactions between water molecules
and graphitic surfaces are often modeled as a simple Lennard-Jones potential
between oxygen and carbon atoms. A possible method for tuning this parameter
consists of simulating a water nanodroplet on a flat graphitic surface,
measuring the equilibrium contact angle, extrapolating it to the limit of a
macroscopic droplet and finally matching this quantity to experimental results.
Considering recent evidence demonstrating that the contact angle of water on a
graphitic plane is much higher than what was previously reported, we estimate
the oxygen-carbon interaction for the recent SPC/Fwwater model. Results
indicate a value of about 0.2 kJ/mol, much lower than previous estimations. We
then perform simulations of cylindrical water filaments on graphitic surfaces,
in order to compare and correlate contact angles resulting from these two
different systems. Results suggest that modified Young's equation does not
describe the relation between contact angle and drop size in the case of
extremely small systems and that contributions different from the one deriving
from contact line tension should be taken into account.Comment: To be published on Physical Review E (http://pre.aps.org/
The Radio Afterglow and Host Galaxy of the Dark GRB 020819
Of the fourteen gamma-ray bursts (GRBs) localized to better than 2' radius
with the SXC on HETE-2, only two lack optical afterglow detections, and the
high recovery rate among this sample has been used to argue that the fraction
of truly dark bursts is ~10%. While a large fraction of earlier dark bursts can
be explained by the failure of ground-based searches to reach appropriate
limiting magnitudes, suppression of the optical light of these SXC dark bursts
seems likely. Here we report the discovery and observation of the radio
afterglow of GRB 020819, an SXC dark burst, which enables us to identify the
likely host galaxy (probability of 99.2%) and hence the redshift (z=0.41) of
the GRB. The radio light curve is qualitatively similar to that of several
other radio afterglows, and may include an early-time contribution from the
emission of the reverse shock. The proposed host is a bright R = 19.5 mag
barred spiral galaxy, with a faint R ~ 24.0 mag "blob'' of emission, 3" from
the galaxy core (16 kpc in projection), that is coincident with the radio
afterglow. Optical photometry of the galaxy and blob, beginning 3 hours after
the burst and extending over more than 100 days, establishes strong upper
limits to the optical brightness of any afterglow or associated supernova.
Combining the afterglow radio fluxes and our earliest R-band limit, we find
that the most likely afterglow model invokes a spherical expansion into a
constant-density (rather than stellar wind-like) external environment; within
the context of this model, a modest local extinction of A_V ~ 1 mag is
sufficient to suppress the optical flux below our limits.Comment: 7 pages, 2 figures. ApJ, in press. For more info on dark bursts, see
http://www.astro.ku.dk/~pallja/dark.htm
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Examining Visual Field Loss in Patients in Glaucoma Clinics During Their Predicted Remaining Lifetime
Purpose.: To evaluate the proportion of patients in glaucoma clinics progressing at rates that would result in visual disability within their expected lifetime.
Methods.: This retrospective study used visual field (VF) series of at least 3 years’ duration from 3790 UK patients in glaucoma clinics calculating rates of loss for each eye using linear regression of mean deviation (MD) over time. Residual life expectancies derived from the UK Office of National Statistics actuarial tables for each patient were combined with these rates to estimate predicted MDs at end of expected lifetime. The proportion of patients projected to progress to visual impairment (MD: −14 dB or worse) or statutory blindness (MD: −22 dB or worse) in both eyes before end of expected lifetime was calculated.
Results.: Only 3.0% (95% confidence interval [CI] 2.7%–3.4%) of patient eyes progressed at faster than −1.5 dB/year (n = 7149 eyes). Of those patients with both eyes followed, 5.2% (CI 4.5%–6.0%) were predicted to progress to statutory blindness, with a further 10.4% (CI 9.4%–11.4%) reaching visual impairment in their lifetime. More than 90% (CI 85.7%–94.3%) of patients predicted to progress to statutory blindness, had an MD worse than −6 dB in at least one eye at presentation.
Conclusions.: This modeling exercise indicates that most patients in glaucoma clinics are not at high risk of progressing to statutory blindness. The likelihood of patients suffering impairment in their lifetimes is linked to VF loss at presentation, which illuminates the importance of reliably detecting significant VF defects in primary care
The Open Access Advantage Revisited
This paper is a revision of one that appeared in 2008, incorporating the many developments and changes that have happened since then.published_or_final_versio
A practical approach to the sensitivity analysis for kinetic Monte Carlo simulation of heterogeneous catalysis
Lattice kinetic Monte Carlo simulations have become a vital tool for
predictive quality atomistic understanding of complex surface chemical
reaction kinetics over a wide range of reaction conditions. In order to expand
their practical value in terms of giving guidelines for the atomic level
design of catalytic systems, it is very desirable to readily evaluate a
sensitivity analysis for a given model. The result of such a sensitivity
analysis quantitatively expresses the dependency of the turnover frequency,
being the main output variable, on the rate constants entering the model. In
the past, the application of sensitivity analysis, such as degree of rate
control, has been hampered by its exuberant computational effort required to
accurately sample numerical derivatives of a property that is obtained from a
stochastic simulation method. In this study, we present an efficient and
robust three-stage approach that is capable of reliably evaluating the
sensitivity measures for stiff microkinetic models as we demonstrate using the
CO oxidation on RuO2(110) as a prototypical reaction. In the first step, we
utilize the Fisher information matrix for filtering out elementary processes
which only yield negligible sensitivity. Then we employ an estimator based on
the linear response theory for calculating the sensitivity measure for non-
critical conditions which covers the majority of cases. Finally, we adapt a
method for sampling coupled finite differences for evaluating the sensitivity
measure for lattice based models. This allows for an efficient evaluation even
in critical regions near a second order phase transition that are hitherto
difficult to control. The combined approach leads to significant computational
savings over straightforward numerical derivatives and should aid in
accelerating the nano-scale design of heterogeneous catalysts
Carbon nanotubes: are they dispersed or dissolved in liquids?
Carbon nanotubes (CNTs) constitute a novel class of nanomaterials with remarkable applications in diverse domains. However, the main intrincsic problem of CNTs is their insolubility or very poor solubility in most of the common solvents. The basic key question here is: are carbon nanotubes dissolved or dispersed in liquids, specifically in water? When analyzing the scientific research articles published in various leading journals, we found that many researchers confused between "dispersion" and "solubilization" and use the terms interchangeably, particularly when stating the interaction of CNTs with liquids. In this article, we address this fundamental issue to give basic insight specifically to the researchers who are working with CNTs as well asgenerally to scientists who deal with nano-related research domains
Size fractionation of trace elements in the surface water and groundwater of the Ganjiang River and Xiushui River basins, China
The research of trace element behaviour and size fractionation is significant to understand the processes in the water-rock system. Moreover, the aqueous speciation of trace elements is strongly related to their distribution and toxicity. In this research, trace elements behaviour and their size fractionation are investigated in the natural water (the surface water and shallow groundwater) of the Ganjiang River and Xiushui River basins. Trace element concentrations were measured by ICP-MS. The authors estimated the size fractionation of the trace elements between suspended forms (>0.45 [mu]m) and dissolved fractions, which included truly dissolved (1 kDa) and colloidal particles (0.45 [mu]m-1 kDa)), after filtration through a 0.45 [mu]m acetate cellulose membrane filter. The distinct features of the trace element size fractionation were identified. The size fractionation of the trace elements under different conditions (in the surface water and shallow groundwater) was studied
Galaxy And Mass Assembly (GAMA) : galaxy close pairs, mergers and the future fate of stellar mass
ASGR acknowledges STFC and SUPA funding that were used to do this work. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO and the participating institutions.We use a highly complete subset of the Galaxy And Mass Assembly II (GAMA-II) redshift sample to fully describe the stellar mass dependence of close pairs and mergers between 10(8) and 10(12)M(circle dot). Using the analytic form of this fit we investigate the total stellar mass accreting on to more massive galaxies across all mass ratios. Depending on how conservatively we select our robust merging systems, the fraction of mass merging on to more massive companions is 2.0-5.6 per cent. Using the GAMA-II data we see no significant evidence for a change in the close pair fraction between redshift z = 0.05 and 0.2. However, we find a systematically higher fraction of galaxies in similar mass close pairs compared to published results over a similar redshift baseline. Using a compendium of data and the function gamma(M) = A(1 + z)(m) to predict the major close pair fraction, we find fitting parameters of A = 0.021 +/- 0.001 and m = 1.53 +/- 0.08, which represents a higher low-redshift normalization and shallower power-law slope than recent literature values. We find that the relative importance of in situ star formation versus galaxy merging is inversely correlated, with star formation dominating the addition of stellar material below M* and merger accretion events dominating beyond M*. We find mergers have a measurable impact on the whole extent of the galaxy stellar mass function (GSMF), manifest as a deepening of the 'dip' in the GSMF over the next similar to Gyr and an increase in M* by as much as 0.01-0.05 dex.Publisher PDFPeer reviewe
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