13,195 research outputs found
Dispersion representations and anomalous singularities of the triangle diagram
We discuss dispersion representations for the triangle diagram
, the single dispersion representation in and the
double dispersion representation in and , with special emphasis
on the appearance of the anomalous singularities and the anomalous cuts in
these representations. For the double dispersion representation in and
, the appearance of the anomalous cut in the region is
demonstrated, and a new derivation of the anomalous double spectral density is
given. We point out that the double spectral representation is particularly
suitable for applications in the region of and/or above the
two-particle thresholds. The dispersion representations for the triangle
diagram in the nonrelativistic limit are studied and compared with the triangle
diagram of the nonrelativistic field theory.Comment: 10 pages, revtex, added a reference, version to be published in Phys.
Rev.
Evidence for view-invariant Face Recognition Units in unfamiliar face learning
Many models of face recognition incorporate the idea of a face recognition unit (FRU). This is an abstracted representation formed from each experience of a face. Longmore et al. (2008) devised a face learning experiment to investigate such a construct (i.e., view-invariance) but failed to find evidence of its existence. Three experiments developed Longmore et al.’s study further by using a different learning task, by employing more stimuli. One or two views of previously unfamiliar faces were shown to participants in a serial matching task (learning). Later, participants attempted to recognise both seen and novel views of the learned faces. Experiment one tested participants’ recognition of a novel view, a day after learning. Experiment two was identical, but tested participants on the same day as learning. And experiment three repeated experiment one, but tested participants on a novel view that was outside the rotation of those views learned. Results revealed a significant advantage for recognising a novel view when two views had been learned, rather than a single learned view – for all experiments. The effect of view-invariance found when both views were learned is discussed
Understanding person acquisition using an interactive activation and competition network
Face perception is one of the most developed visual skills that humans display, and recent work has attempted to examine the mechanisms involved in face perception through noting how neural networks achieve the same performance. The purpose of the present paper is to extend this approach to look not just at human face recognition, but also at human face acquisition. Experiment 1 presents empirical data to describe the acquisition over time of appropriate representations for newly encountered faces. These results are compared with those of Simulation 1, in which a modified IAC network capable of modelling the acquisition process is generated. Experiment 2 and Simulation 2 explore the mechanisms of learning further, and it is demonstrated that the acquisition of a set of associated new facts is easier than the acquisition of individual facts in isolation of one another. This is explained in terms of the advantage gained from additional inputs and mutual reinforcement of developing links within an interactive neural network system. <br/
Simulating disease transmission dynamics at a multi-scale level
We present a model of the global spread of a generic human infectious disease using a Monte Carlo micro-simulation with large-scale parallel-processing. This prototype has been constructed and tested on a model of the entire population of the British Isles. Typical results are presented. A microsimulation of this order of magnitude of population simulation has not been previously attained. Further, an efficiency assessment of processor usage indicates that extension to the global scale is feasible. We conclude that the flexible approach outlined provides the framework for a virtual laboratory capable of supporting public health policy making at a variety of spatial scales.high-performance computing; global modelling; disease transmission
Design comparison of cesium and potassium vapor turbine-generator units for space power
Design comparison of cesium and potassium vapor turbogenerator units for space power plant
Quadrilateral-octagon coordinates for almost normal surfaces
Normal and almost normal surfaces are essential tools for algorithmic
3-manifold topology, but to use them requires exponentially slow enumeration
algorithms in a high-dimensional vector space. The quadrilateral coordinates of
Tollefson alleviate this problem considerably for normal surfaces, by reducing
the dimension of this vector space from 7n to 3n (where n is the complexity of
the underlying triangulation). Here we develop an analogous theory for
octagonal almost normal surfaces, using quadrilateral and octagon coordinates
to reduce this dimension from 10n to 6n. As an application, we show that
quadrilateral-octagon coordinates can be used exclusively in the streamlined
3-sphere recognition algorithm of Jaco, Rubinstein and Thompson, reducing
experimental running times by factors of thousands. We also introduce joint
coordinates, a system with only 3n dimensions for octagonal almost normal
surfaces that has appealing geometric properties.Comment: 34 pages, 20 figures; v2: Simplified the proof of Theorem 4.5 using
cohomology, plus other minor changes; v3: Minor housekeepin
Use of a Crop Simulation Model to Provide Long-Term Data for Economic Analysis: the Case of Early Maturing Soybeans
A target MOTAD model is used to investigate incorporation of early maturing soybeans by a crop farm in southeastern Kansas. Weather (WGEN) and crop simulation (SOYGRO) models are used to generate a long-term series of soybean yields. Results indicate that early maturing soybeans offer a risk-reducing diversification strategy.Crop Production/Industries, Farm Management,
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