274 research outputs found
Isoparametric 3-D Finite Element Mesh Generation Using Interactive Computer Graphics
An isoparametric 3-D finite element mesh generator was developed with direct interface to an interactive geometric modeler program called POLYGON. POLYGON defines the model geometry in terms of boundaries and mesh regions for the mesh generator. The mesh generator controls the mesh flow through the 2-dimensional spans of regions by using the topological data and defines the connectivity between regions. The program is menu driven and the user has a control of element density and biasing through the spans and can also apply boundary conditions, loads interactively
Self-Supervised Learning with an Information Maximization Criterion
Self-supervised learning allows AI systems to learn effective representations
from large amounts of data using tasks that do not require costly labeling.
Mode collapse, i.e., the model producing identical representations for all
inputs, is a central problem to many self-supervised learning approaches,
making self-supervised tasks, such as matching distorted variants of the
inputs, ineffective. In this article, we argue that a straightforward
application of information maximization among alternative latent
representations of the same input naturally solves the collapse problem and
achieves competitive empirical results. We propose a self-supervised learning
method, CorInfoMax, that uses a second-order statistics-based mutual
information measure that reflects the level of correlation among its arguments.
Maximizing this correlative information measure between alternative
representations of the same input serves two purposes: (1) it avoids the
collapse problem by generating feature vectors with non-degenerate covariances;
(2) it establishes relevance among alternative representations by increasing
the linear dependence among them. An approximation of the proposed information
maximization objective simplifies to a Euclidean distance-based objective
function regularized by the log-determinant of the feature covariance matrix.
The regularization term acts as a natural barrier against feature space
degeneracy. Consequently, beyond avoiding complete output collapse to a single
point, the proposed approach also prevents dimensional collapse by encouraging
the spread of information across the whole feature space. Numerical experiments
demonstrate that CorInfoMax achieves better or competitive performance results
relative to the state-of-the-art SSL approaches
Evaluation of phenolic contents and antioxidant activity of various solvent extracts of Sonchus asper (L.) Hill
<p>Abstract</p> <p>Background</p> <p><it>Sonchus asper </it>(SA) is traditionally used for the treatment of various ailments associated with liver, lungs and kidneys. This study was aimed to investigate the therapeutic potential of nonpolar (hexane, SAHE; ethyl acetate, SAEE and chloroform, SACE) and polar (methanol, SAME) crude extracts of the whole plant.</p> <p>Methods</p> <p>To achieve these goals, several parameters including free-radical (DPPH<sup>•</sup>, ABTS<sup>•+</sup>, H<sub>2</sub>O<sub>2 </sub>and <sup>•</sup>OH) scavenging, iron chelating activity, scavenging of superoxide radicals, total flavonoids and total phenolic content (TPC) were examined.</p> <p>Results</p> <p>The SA extracts presented a remarkable capacity to scavenge all the tested reactive species with IC<sub>50 </sub>values being found at the μg ⁄ ml level. The SAME was shown to have the highest TPCs while lowest IC<sub>50 </sub>values for the DPPH<sup>•</sup>, ABTS<sup>•+ </sup>radical scavenging capacities and iron chelating scavenging efficiency, moreover, SAME had best activities in scavenging of superoxide radicals and hydrogen peroxide as well as potently scavenged the hydroxyl radicals.</p> <p>Conclusion</p> <p>These results suggest the potential of <it>S. asper </it>as a medicine against free-radical-associated oxidative damage.</p
Quantitative electron phase imaging with high sensitivity and an unlimited field of view
As it passes through a sample, an electron beam scatters, producing an exit wavefront rich in information. A range of material properties, from electric and magnetic field strengths to specimen thickness, strain maps and mean inner potentials, can be extrapolated from its phase and mapped at the nanoscale. Unfortunately, the phase signal is not straightforward to obtain. It is most commonly measured using off-axis electron holography, but this is experimentally challenging, places constraints on the sample and has a limited field of view. Here we report an alternative method that avoids these limitations and is easily implemented on an unmodified transmission electron microscope (TEM) operating in the familiar selected area diffraction mode. We use ptychography, an imaging technique popular amongst the X-ray microscopy community; recent advances in reconstruction algorithms now reveal its potential as a tool for highly sensitive, quantitative electron phase imaging
Photographic protocol for image acquisition in craniofacial microsomia
Craniofacial microsomia (CFM) is a congenital condition associated with orbital, mandibular, ear, nerve, and soft tissue anomalies. We present a standardized, two-dimensional, digital photographic protocol designed to capture the common craniofacial features associated with CFM
Rationale and recommendations on decolonising the pedagogy and curriculum of the Law School at the University of Exeter
This is the final version. Available on open access from Routledge via the DOI in this recordThis report outlines the rationale behind and recommendations on the steps that need to be taken towards decolonising the Law School's pedagogy and curriculum. It concludes a two-year process of research and discussions involving a joint effort between staff and students. A rationale for a change in approach to both pedagogy and curriculum is presented together with recommendations and practical examples of how this might be achieved in modular teaching in the Law School
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