An experimental test of plant canopy reflectance models on cotton

Extensive data on the plant parameters necessary to evaluate any model are presented for a cotton crop. The variation of the bidirectional reflectance function with observer altitude, observer azimuth, and sun altitude angle is presented for a high density cotton crop having leaf index of 19. A comparison with the quantitative behavior obtained from the Suits model is accomplished in the wavelength region from 400 nm to 1050 nm

The Effect of Prescribed Fires on Vernal Herbs

The effects of fire on vernal herbs are little known. David Kem attempted to assess the influences of spring and winter prescribed fires on vernal herbs by collecting abundance data on three sets of research plots located at the WKU Green River Preserve in Hart County, KY, on April 9-10, 2010. On April 10 he conducted spring burns, and on February 22, 2011, he conducted winter burns. He then collected post-fire data on the abundance of the herbs on the 12-19 of March, 2011. He found little influence of fire on overall species richness and the density of common species. In spring of 2015, these plots were re-sampled. Results indicated that there was a change between years in overall stem density and the density of several common vernal herbs, including Dentaria laciniata and Claytonia virginica. There was also a slight change in species richness between years. Fire treatment was found to have little or no effect on herb stem density and species richness. We suspect that changes between years could be caused by differing precipitation amounts for each respective year

A plant canopy light absorption model with application to wheat

From the light absorption model the absorption of light in the photosynthetically active region of the spectrum was calculated for a Penjamo wheat crop for several situations including: (1) the percent absorption of the incident radiation by a canopy having a four layer structure; (2) the percent absorption of light by the individual layers within a four layer canopy and by the underlying soil; (3) the percent absorption of light by each vegetative canopy layer for variable sun angle; and (4) the cumulative solar energy absorbed by the developing wheat canopy as it progresses from a single layer through its growth stages to a three layer canopy. This calculation was also presented as a function of the leaf area index

Seasonal soybean crop reflectance

Data are presented from field measurements of 1980 including 5 acquisitions of handheld radiometer reflectance measurements, 7 complete sets of parameters for implementing the Suits mode, and other biophysical parameters to characterize the soybean canopy. LANDSAT calculations on the simulated Brazilian soybean reflectance are included along with data collected during the summer and fall on 1981 on soybean single leaf optical parameters for three irrigation treatments. Tests of the Suits vegetative canopy reflectance model for the full hemisphere of observer directions as well as the nadir direction show moderate agreement for the visible channels of the MSS and poor agreement in the near infrared channel. Temporal changes in the spectral characteristics of the single leaves were seen to occur as a function of maturity which demonstrates that the absorptance of a soybean single leaf is more a function of thetransmittancee characteristics than the seasonally consistent single leaf reflectance

F. [LeMaster] to James (2 October 1962)

https://egrove.olemiss.edu/mercorr_anti/1113/thumbnail.jp

Multifluid magnetohydrodynamic turbulent decay

It is generally believed that turbulence has a significant impact on the dynamics and evolution of molecular clouds and the star formation which occurs within them. Non-ideal magnetohydrodynamic effects are known to influence the nature of this turbulence. We present the results of a suite of 512-cubed resolution simulations of the decay of initially super-Alfvenic and supersonic fully multifluid MHD turbulence. We find that ambipolar diffusion increases the rate of decay of the turbulence while the Hall effect has virtually no impact. The decay of the kinetic energy can be fitted as a power-law in time and the exponent is found to be -1.34 for fully multifluid MHD turbulence. The power spectra of density, velocity and magnetic field are all steepened significantly by the inclusion of non-ideal terms. The dominant reason for this steepening is ambipolar diffusion with the Hall effect again playing a minimal role except at short length scales where it creates extra structure in the magnetic field. Interestingly we find that, at least at these resolutions, the majority of the physics of multifluid turbulence can be captured by simply introducing fixed (in time and space) resistive terms into the induction equation without the need for a full multifluid MHD treatment. The velocity dispersion is also examined and, in common with previously published results, it is found not to be power-law in nature.Comment: 16 pages, 15 figures, Accepted for publication in Ap

Multi-Scale Peripheral Vasculopathy with Metabolic Syndrome

The combination of cardiovascular and metabolic risk factors including obesity, dyslipidemia, hypertension, and insulin resistance, in combination with a prothrombotic and proinflammatory state, is a condition termed Metabolic Syndrome (METS). Twenty percent of the adult population is afflicted with METS which increases the risk of type-2 diabetes mellitus and cardiovascular disease. Further, the presence of peripheral vascular disease (PVD) is tightly coupled with METS which is a perfusion-demand mismatch of blood supply to active skeletal muscle resulting in painful claudication and a late-stage potential for amputation. The underlying contributors of METS associated micro-vasculopathies in the skeletal muscle, their impact on impaired perfusion, and the potential for reversibility remain unclear. Owing its hyperphagia to leptin signaling resistance, the obese Zucker rat (OZR) is a translationally relevant model for human METS and the associated micro-vasculopathies. The overall purpose of this thesis is to utilize a multi-scale approach, particularly intravital microscopy and isolate vessels, to garner a greater understanding of the observed OZR vasculopathies and to investigate the potential of therapeutic interventions for their reversibility. Project 1: The purpose was to identify any alterations in postcapillary and collecting venule function in the OZR compared to healthy controls. The OZR presented with impaired dilator reactivity and elevation in thromboxane A2 constrictor responses for both postcapillary and collecting venules. Project 2: The purpose was to identify the possible contributors of a disconnect for in-situ and ex-vivo vascular studies utilizing the OZR model. Using a multi-scale approach, Project 2 provides insight to this disconnect and reveals a heterogenous adrenergic response in the OZR, giving rise to new potential avenues of study. Project 3: The purpose was to determine the potential for reversibility or restoration of established PVD using the chronic ingestion of an HMG-CoA inhibitor, atorvastatin, and/or the implementation of regular exercise. Following a seven-week intervention, the intervention groups revealed vascular improvements with the combination group having the greatest capacity for reversibility (in specific indices). Significance: Therefore, this thesis further advances the understanding of METS associated PVD as well as potential modes for improvement following its establishment