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Vegetable and Fruit Variety Trials Spring 2014
Get PDF"March 2015." Includes results from Auburn University, University of Georgia, North Carolina State University, and Mississippi State University
One- and two-dimensional hybrid simulations of whistler mode waves in a dipole field
Get PDFWe simulate whistler mode waves using a hybrid code. There are four species in the simulations, hot electrons initialized with a bi-Maxwellian distribution with temperature in the direction perpendicular to background magnetic field greater than that in the parallel direction, warm isotropic electrons, cold inertialess fluid electrons, and protons as an immobile background. The density of the hot population is a small fraction of the total plasma density. Comparison between the dispersion relation of our model and other dispersion relations shows that our model is more accurate for lower frequency whistlers than for higher frequency whistlers. Simulations in 2-D Cartesian coordinates agree very well with those using a full dynamics code. In the 1-D simulations along the dipole magnetic field, the predicted frequency and wave number are observed. Rising tones are observed in the one-fourteenth scale simulations that have larger than realistic magnetic field spatial inhomogeneity. However, in the full-scale 1-D simulation in a dipole field, the waves are more broadband and do not exhibit rising tones. In the 2-D simulations in a meridional plane, the waves are generated with propagation approximately parallel to the background magnetic field. However, the wavefronts become oblique as they propagate to higher latitudes. Simulations with different plasma density profiles across L shell are performed to study the effect of the background density on whistler propagation.Publishe
Framework for identifying implemenation issues affecting extension human science programming Supplemental References
No full textResponses of global terrestrial evapotranspiration to climate change and increasing atmospheric CO2 in the 21st century
Get PDFQuantifying the spatial and temporal patterns of the water lost to the atmosphere through land surface evapotranspiration (ET) is essential for understanding the global hydrological cycle, but remains much uncertain. In this study, we use the Dynamic Land Ecosystem Model to estimate the global terrestrial ET during 2000-2009 and project its changes in response to climate change and increasing atmospheric CO2 under two IPCC SRES scenarios (A2 and B1) during 2010-2099. Modeled results show a mean annual global terrestrial ET of about 549 (545-552) mm yr(-1) during 2000-2009. Relative to the 2000s, global terrestrial ET for the 2090s would increase by 30.7 mm yr(-1) (5.6%) and 13.2 mm yr(-1) (2.4%) under the A2 and B1 scenarios, respectively. About 60% of global land area would experience increasing ET at rates of over 9.5 mm decade(-1) over the study period under the A2 scenario. The Arctic region would have the largest ET increase (16% compared with the 2000s level) due to larger increase in temperature than other regions. Decreased ET would mainly take place in regions like central and western Asia, northern Africa, Australia, eastern South America, and Greenland due to declines in soil moisture and changing rainfall patterns. Our results indicate that warming temperature and increasing precipitation would result in large increase in ET by the end of the 21st century, while increasing atmospheric CO2 would be responsible for decrease in ET, given the reduction of stomatal conductance under elevated CO2.PublishedYe
Using Infographics to Teach Source Evaluation to Biology Freshmen
Get PDFGiven the immediate visual impact of infographics as well as the ease of creating them, infographics are an effective way to communicate complex information. However, viewers of infographics may draw very different conclusions depending on how the data are presented. I worked with a Biology professor to develop two epidemiology-themed information literacy classes on infographics. We had two goals for these sessions: 1) Students would be able to apply evaluative criteria to infographic sources in order to judge accuracy, bias, and quality of infographics; and 2) students would be able to locate appropriate data sources in order to create their own infographics. I will describe the development and outcome of the classes, as well as the benefits to students, faculty member, and librarian.N
Explaining the Railsback stretch in terms of the inharmonicity of piano tones and sensory dissonance
Get PDFThe perceptual results of Plomp and Levelt for the sensory dissonance of a pair of
pure tones are used to estimate the dissonance of pairs of piano tones. By using the spectra of tones measured for a real piano, the effect of the inharmonicity of the tones is included. This leads to a prediction for how the tuning of this piano should deviate from an ideal equal tempered scale so as to give the smallest sensory dissonance and hence give the most pleasing tuning. The results agree with the well known "Railsback stretch," the average tuning curve produced by skilled piano technicians. This is the first quantitative explanation of the magnitude of the Railsback stretch in terms of the human perception of dissonance
Maskelynite formation via solid-state transformation: Evidence of infrared and X-ray anisotropy
Get PDFWe present the results of a combined study of shocked labradorite from the Lonar crater, India, using optical microscopy, micro-Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, high-energy X-ray total scattering experiments, and micro-Fourier transform infrared (micro-FTIR) spectroscopy. We show that maskelynite of shock class 2 is structurally more similar to fused glass than to crystalline plagioclase. However, there are slight but significant differencespreservation of original preimpact igneous zoning, anisotropy at infrared wavelengths, X-ray anisotropy, and preservation of some intermediate range orderwhich are all consistent with a solid-state transformation from plagioclase to maskelynite.Publishe
A Life Reclaimed: George Evans (1766-1857) of Norbury, Winster, Derby and Belper
No full textArticle from the George Eliot Review, digitized and hosted by the George Eliot Review Online.Publishe
Trust region methods for estimation of a complex exponential decay model in MRI with a single-shot or multi-shot trajectory (in review)
Get PDFJoint estimation of spin density, R2* decay and off-resonance frequency maps is very useful in many magnetic resonance imaging (MRI) applications. The standard multi-echo approach can achieve high accuracy but requires a long acquisition time for sampling multiple k-space frames. There are many approaches to accelerate the acquisition. Among them, single- or multi-shot trajectory based sampling has recently drawn attention due to its fast data acquisition. However, this sampling strategy destroys the Fourier relationship between k-space and images, leading to a great challenge for the reconstruction. In this work, we present two trust region methods based on two different linearization strategies for the nonlinear signal model. A trust region is defined as a local area in the variable space where a local linear approximation is trustable. In each iteration, the method minimizes a local approximation within a trust region so that the step size can be kept in a suitable scale. A continuation scheme is applied to gradually reduce the regularization over the parameter maps and facilitate convergence from poor initializations. The two trust region methods are compared to two other previously proposed methods---the nonlinear conjugate gradients and the gradual refinement algorithm. Experiments based on various synthetic data and real phantom data show that the two trust region methods have a clear advantage in both speed and stability