62,681 research outputs found
Probing the link between residual entropy and viscosity of molecular fluids and model potentials
This work investigates the link between residual entropy and viscosity based
on wide-ranging, highly accurate experimental and simulation data. This link
was originally postulated by Rosenfeld in 1977, and it is shown that this
scaling results in an approximately monovariate relationship between residual
entropy and reduced viscosity for a wide range of molecular fluids (argon,
methane, CO2, SF6, refrigerant R-134a (1,1,1,2-tetrafluoroethane), refrigerant
R-125 (pentafluoroethane), methanol, and water), and a range of model
potentials (hard sphere, inverse power, Lennard-Jones, and
Weeks-Chandler-Andersen). While the proposed "universal" correlation of
Rosenfeld is shown to be far from universal, when used with the appropriate
density scaling for molecular fluids, the viscosity of non-associating
molecular fluids can be mapped onto the model potentials. This mapping results
in a length scale that is proportional to the cube root of experimentally
measureable liquid volume values
Fiber optic crossbar switch for automatically patching optical signals
A system for automatically optically switching fiber optic data signals between a plurality of input optical fibers and selective ones of a plurality of output fibers is described. The system includes optical detectors which are connected to each of the input fibers for converting the optic data signals appearing at the respective input fibers to an RF signal. A plurality of RF to optical signal converters are arranged in rows and columns. The output of each of the optical detectors are each applied to a respective row of optical signal converted for being converters back to an optical signal when the particular optical signal converter is selectively activated by a dc voltage
YouTube as a repository : the creative practice of students as producers of Open Educational Resources
In this paper we present an alternative view of Open Educational Resources (OERs). Rather than focusing on open media resources produced by expert practitioners for use by peers and learners, we examine the practice of learners as active agents, producing open media resources using the devices in their pockets: their mobile phones. In this study, students are the producers and operate simultaneously as legitimate members of the YouTube community and producers of educational content for future cohorts. Taking an Action Research approach we investigated how studentās engagement with open media resources related to their creativity. Using Kleimanās framework of fives conceptual themes which emerged from academics experiences of creativity (constraint, process, product, transformation, fulfillment), we found that these themes revealed the opportunities designed into the assessed task and provided a useful lens with which to view studentsā authentic creative experiences.
Studentsā experience of creativity mapped on to Kleimanās framework, and was affected by assessment. Dimensions of openness changed across platforms, although the impact of authenticity and publication on creativity was evident, and the production of open media resources that have a dual function as OERs has clear benefits in terms of knowledge sharing and community participation.The transformational impacts for students were evident in the short term but would merit a longitudinal study. A series of conclusions are drawn to inform future practice and research
Stoichiometry control of the electronic properties of the LaAlO_3/SrTiO_3 heterointerface
We investigate the effect of the laser parameters of pulsed laser deposition
on the film stoichiometry and electronic properties of LaAlO_3/SrTiO_3 (001)
heterostructures. The La/Al ratio in the LaAlO_3 films was varied over a wide
range from 0.88 to 1.15, and was found to have a strong effect on the interface
conductivity. In particular, the carrier density is modulated over more than
two orders of magnitude. The film lattice expansion, caused by cation
vacancies, is found to be the important functional parameter. These results can
be understood to arise from the variations in the electrostatic boundary
conditions, and their resolution, with stoichiometry.Comment: 4 pages, 3 figures, submitted for publicatio
Quadrature domains and kernel function zipping
It is proved that quadrature domains are ubiquitous in a very strong sense in
the realm of smoothly bounded multiply connected domains in the plane. In fact,
they are so dense that one might as well assume that any given smooth domain
one is dealing with is a quadrature domain, and this allows access to a host of
strong conditions on the classical kernel functions associated to the domain.
Following this string of ideas leads to the discovery that the Bergman kernel
can be zipped down to a strikingly small data set. It is also proved that the
kernel functions associated to a quadrature domain must be algebraic.Comment: 13 pages, to appear in Arkiv for matemati
Dramatic Mobility Enhancements in Doped SrTiO3 Thin Films by Defect Management
We report bulk-quality n-type SrTiO3 (n-SrTiO3) thin films fabricated by
pulsed laser deposition, with electron mobility as high as 6600 cm2 V-1 s-1 at
2 K and carrier density as low as 2.0 x 10^18cm-3 (~ 0.02 at. %), far exceeding
previous pulsed laser deposition films. This result stems from precise
strontium and oxygen vacancy defect chemistry management, providing a general
approach for defect control in complex oxide heteroepitaxy.Comment: 13 pages, 4 figure
Ethnic differences in adiposity and diabetes risk ā insights from genetic studies
Type 2 diabetes is more common in non-Europeans and starts at a younger age and at lower BMI cut-offs. This review discusses the insights from genetic studies about pathophysiological mechanisms which determine risk of disease with a focus on the role of adiposity and body fat distribution in ethnic disparity in risk of type 2 diabetes. During the past decade, genome-wide association studies (GWAS) have identified more than 400 genetic variants associated with the risk of type 2 diabetes. The Eurocentric nature of these genetic studies have made them less effective in identifying mechanisms that make non-Europeans more susceptible to higher risk of disease. One possible mechanism suggested by epidemiological studies is the role of ethnic difference in body fat distribution. Using genetic variants associated with an ability to store extra fat in a safe place, which is subcutaneous adipose tissue, we discuss how different ethnic groups could be genetically less susceptible to type 2 diabetes by developing a more favourable fat distribution
Platform-basin transitions and their role in Alpine-style collision systems : a comparative approach
CB acknowledges financial support from Optimus (Aberdeen) ltd. Petroceltic International plc are thanked for providing access to the subsurface data used in this study and for permission to publish images used here. Schlumberger are thanked for providing use of Petrel software under their academic agreement with the University of Aberdeen. RWHB thanks the organisers of the 12th Emile Argand Conference on Alpine Geological Studies for the invitation and financial support to participate in the Montgenevre workshop. Reviewers Enrico Tavarnelli, Thierry Dumont and editors Christian Sue and Stefan Schmid are all thanked for their comments that have significantly improved this contribution.Peer reviewedPublisher PD
Predicting real-time roadside CO and NO2 concentrations using neural networks
The main aim of this paper is to develop a model based on neural network (NN) theory to estimate real-time roadside CO and concentrations using traffic and meteorological condition data. The location of the study site is at a road intersection in Melton Mowbray, which is a town in Leicestershire, U.K. Several NNs, which can be classified into three types, namely, the multilayer perceptron, the radial basis function, and the modular network, were developed to model the nonlinear relationships that exist in the pollutant concentrations. Their performances are analyzed and compared. The transferability of the developed models is studied using data collected from a road intersection in another city. It was concluded that all NNs provide reliable estimates of pollutant concentrations using limited information and noisy data
Predicting real-time roadside CO and NO2 concentrations using neural networks
The main aim of this paper is to develop a model based on neural network (NN) theory to estimate real-time roadside CO and concentrations using traffic and meteorological condition data. The location of the study site is at a road intersection in Melton Mowbray, which is a town in Leicestershire, U.K. Several NNs, which can be classified into three types, namely, the multilayer perceptron, the radial basis function, and the modular network, were developed to model the nonlinear relationships that exist in the pollutant concentrations. Their performances are analyzed and compared. The transferability of the developed models is studied using data collected from a road intersection in another city. It was concluded that all NNs provide reliable estimates of pollutant concentrations using limited information and noisy data
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