MULES IN SOUTHERN AGRICULTURE: REVISITED

This article provides additional empirical evidence concerning the choice of the mule as the dominant draft animal in southern agricultural production in the latter 19th and early 20th century. While the mule was uniquely suited to the crops and climate of the region, two divergent arguments have been presented as to why the mule was the dominant draft animal in southern agricultural production. This research reevaluates these arguments and provides evidence that it was, in fact, the characteristics of this hybrid that made it the preferred draft animal for the South.mule, land owners, part owners, and managers, share tenants, sharecroppers, principal agent problem, Farm Management, N51, O13, Q12, Q13,

X-Ray Fluorescence Applications in Mudrock Characterization: Investigations into Middle Devonian Stratigraphy, Appalachian Basin, USA

Mudrocks are characterized by nanometer-scale pore sizes and nano-darcy permeability, which plays a significant role in hydrocarbon flow during production. Resulting from these characteristics, mudrocks were exclusively considered a source rock, which charged overlying, more porous mediums. Hydraulic fracturing, a technology used to create artificial fractures to liberate hydrocarbons from the reservoir, enabled natural gas to be produced from mudrock reservoirs economically. Over the last fifteen years, this technology motivated research efforts to understand reservoir characteristics of mudrock. These investigations significantly improved our knowledge of mudrock systems, but have also highlighted key areas that are undeveloped and/or where conflicting hypotheses exist. Utilizing wave-dispersive X-ray fluorescence (XRF) and high-resolution handheld energy-dispersive X-ray fluorescence (hhEDXRF) datasets collected from seven middle Devonian core throughout the Appalachian basin, this dissertation focuses on three areas of mudrock research: (1) development of mudrock calibrations to increase the analytical quality of hhEDXRF datasets, (2) investigation into the relationship between chemical composition of the host rock and natural fracture presence, and (3) assessment of the relationship between paleo-depositional conditions and organic carbon enrichment. This research indicates that lithology-specific calibrations significantly increase the analytical quality of hhEDXRF datasets, natural fractures preferential concentrate in zones of similar composition in a predictable manner, and an interplay of limited dilution and a robust anoxia-productivity feedback mechanism controlled organic carbon enrichment within middle Devonian mudrock of the Appalachian basin

Effects of Application Timing and Soil Type on Optimal N Rate Requirement of Sugarcane (Saccharum spp.) and Changes in Soil Inorganic and Leaf N Concentrations

Research is limited on the effects of soil types and early nitrogen (N) fertilizer applications to N management strategies in sugarcane (Saccharum spp.) production in Louisiana. This study was established in 2015 at two locations in St. Gabriel, LA to 1) determine the effect of fertilizer application timing and soil type on the optimal N rate requirement and yield of sugarcane and 2) relate the relationship of soil and leaf N content to yield at different growth stages with sugarcane yield. Treatments were set in a randomized block design on a clay soil and in a complete randomized design on silt loam soil, using sugarcane variety L01-299. Granular (Agrocote Max®, 45%N) and solution (urea ammonium nitrate solution-UAN, 32%N) N sources were applied at rates of 45, 90 and 135 kg N ha-1 and at two application timings (March and April). All treatments including a control (0 kg N ha-1) were replicated four times. Sugarcane yield was recorded at harvest. Sequential sampling of soil were done at two depths (0-15 and 15-30 cm) and leaf below the top visible dewlap (TVD). The N application timing did not have a large effect on inorganic N release within the soil particularly outside the active N uptake growth period of sugarcane. The optimal N rates on the silt loam soil using UAN fertilizer applied in March were 39 and 43 kg N ha-1, yielding 14,102 kg sugar ha-1 and 117 Mg cane ha-1. Yield for sugarcane applied with CRF were maximized at lower N rates, but resulted in lower yields. The positive linear relationship between leaf N content and yield was highest in mid-May sampling with r = 0.85 for cane and sugar yield. Highest correlations between leaf N content and soil inorganic N were all within 8 WANF, with April-applied fertilizer showing high correlations between the two variables earlier than March-applied fertilizer. The dynamic nature of inorganic N in Louisiana can be better understood and more efficiently utilized for sugarcane production through further research on the effects of N management practices and site-specific factors

Modelling Immunological Memory

Accurate immunological models offer the possibility of performing highthroughput experiments in silico that can predict, or at least suggest, in vivo phenomena. In this chapter, we compare various models of immunological memory. We first validate an experimental immunological simulator, developed by the authors, by simulating several theories of immunological memory with known results. We then use the same system to evaluate the predicted effects of a theory of immunological memory. The resulting model has not been explored before in artificial immune systems research, and we compare the simulated in silico output with in vivo measurements. Although the theory appears valid, we suggest that there are a common set of reasons why immunological memory models are a useful support tool; not conclusive in themselves

Optical fibre digital pulse-position-modulation assuming a Gaussian received pulse shape

The abundance in bandwidth available in the best monomode fibres may be exchanged for improved receiver sensitivity by employing digital PPM. The paper presents a performance and optimisation analysis for a digital PPM coding scheme operating over a fibre channel employing a PIN-BJT receiver and assuming a Gaussian received pulse shape. The authors present original results for a 50 Mbit/s, 1.3 μm wavelength digital PPM system and conclude that, provided the fibre bandwidth is several times that of the data rate, digital PPM can outperform commercially available PIN-BJT binary PCM system

Freeze-free cosmological evolution with a non-monotonic internal clock

Given the lack of an absolute time parameter in general relativistic systems, quantum cosmology often describes the expansion of the universe in terms of relational changes between two degrees of freedom, such as matter and geometry. However, if clock degrees of freedom (self-)interact non-trivially, they in general have turning points where their momenta vanish. At and beyond a turning point, the evolution of other degrees of freedom is no longer described directly by changes of the clock parameter because it stops and then turns back, while time is moving forward. Previous attempts to describe quantum evolution relative to a clock with turning points have failed and led to frozen evolution in which degrees of freedom remain constant while the clock parameter, interpreted directly as a substitute for monotonic time, is being pushed beyond its turning point. Here, a new method previously used in oscillator systems is applied to a tractable cosmological model, given by an isotropic universe with spatial curvature and scalar matter. The re-collapsing scale factor presents an example of a clock with a single turning point. The method succeeds in defining unitary and freeze-free evolution by unwinding the turning point of the clock, introducing an effective monotonic time parameter that is related to but not identical with the non-monotonic clock degree of freedom. Characteristic new quantum features are found around the turning point, based on analytical and numerical calculations.Comment: 24 pages, 4 figure

Mapping the optical absorption of a substrate-transferred crystalline AlGaAs coating at 1.5 µm

The sensitivity of 2nd and 3rd generations of interferometric gravitational wave detectors will be limited by thermal noise of the test-mass mirrors and highly reflective coatings. Recently developed crystalline coatings show a promising thermal noise reduction compared to presently used amorphous coatings. However, stringent requirements apply to the optical properties of the coatings as well. We have mapped the optical absorption of a crystalline AlGaAs coating which is optimized for high reflectivity for a wavelength of 1064nm. The absorption was measured at 1550nm where the coating stack transmits approximately 70% of the laser light. The measured absorption was lower than (30.2 +/- 11.1)ppm which is equivalent to (3.6 +/- 1.3)ppm for a coating stack that is highly reflective at 1530nm. While this is a very promising low absorption result for alternative low--loss coating materials, further work will be necessary to reach the requirements of <1ppm for future gravitational wave detectors. Jessica Steinlechner, Iain W Martin, Angus Bell, Garrett Cole, Jim Hough, Steven Penn, Sheila Rowan, Sebastian Steinlechne