QUANTITY OF LIVING PLANT MATERIALS IN PRAIRIE SOILS IN RELATION TO RUN-OFF AND SOIL EROSION

The menace of soil erosion did not appear in the west until much of the prairie was broken for cropping or weakened by continuous overgrazing. The grassland sod is a great conserver of rainfall; the amount of run-off water is relatively small, and the soil is firmly held against the forces of erosion. This study is concerned with the role that the living underground plant parts play in promoting the absorption of water by the soil, and especially their importance in reducing run-off. Their holding of the soil against the forces of water erosion has been experimentally determined. A study of the quantity of living plant materials in native prairies and pastures near Lincoln, Nebraska, has just been completed. These materials-largely the underground parts of grasses-are composed of roots, rhizomes, and the bases of stems. In the case of non-grassy species or forbs, they sometimes include corms, bulbs, and certain other underground plant structures. The relation of the vegetation to the effectiveness of the precipitation in supplying water to the soil is one of great importance. When the fate of the water falling as drops of rain is studied, it is found that a part is intercepted by the vegetation and never reaches the soil. Much water is lost as run-off when absorption is not sufficiently rapid. This frequently results in erosion. Large amounts are absorbed by the soil and again used by the plant, especially when the vegetation has produced good soil structure and abundant humus. Some water may percolate beyond the depths of the roots of even the most deeply rooted species. The cover of vegetation and the amount of living and dead organic materials in the soil both play an extremely important role in all of these processes. Although this study is not concerned primarily with the effects of the cover of vegetation on soil water relations, yet plant cover is closely related to quantity of underground plant parts and to run-off. Hence, brief consideration will be given to the interception of rainfall, decrease in run-off, and promotion of absorption by the cover of vegetation

Equitable Conversion in Washington: The Doctrine That Dares Not Speak Its Name

Since the 1925 decision of Ashford v. Reese, Washington has had the distinction of being the only American jurisdiction totally, albeit implicitly, to reject the doctrine of equitable conversion. Ashford was overruled in 1977, in a remarkable opinion which simultaneously, and explicitly, rejected the doctrine of equitable conversion, thus maintaining Washington\u27s unique status with respect to that doctrine. But the opinion failed to provide a substitute for either the rule of Ashford or the contrary doctrine of equitable conversion, both of which it emphatically abjured. The result is an unbroken line of Washington cases consistent with only one rule of law-the doctrine of equitable conversion. The effect of the opinion is thus de jure rejection and de facto adoption of equitable conversion. This article will analyze the process by which Washington has managed to achieve substantial conformity with the majority of American jurisdictions, while resolutely maintaining a unique stance

Equitable Conversion in Washington: The Doctrine That Dares Not Speak Its Name

Since the 1925 decision of Ashford v. Reese, Washington has had the distinction of being the only American jurisdiction totally, albeit implicitly, to reject the doctrine of equitable conversion. Ashford was overruled in 1977, in a remarkable opinion which simultaneously, and explicitly, rejected the doctrine of equitable conversion, thus maintaining Washington\u27s unique status with respect to that doctrine. But the opinion failed to provide a substitute for either the rule of Ashford or the contrary doctrine of equitable conversion, both of which it emphatically abjured. The result is an unbroken line of Washington cases consistent with only one rule of law-the doctrine of equitable conversion. The effect of the opinion is thus de jure rejection and de facto adoption of equitable conversion. This article will analyze the process by which Washington has managed to achieve substantial conformity with the majority of American jurisdictions, while resolutely maintaining a unique stance

Model based estimation of parameters of spatial populations from probability samples

Many ecological populations can be interpreted as response surfaces; the spatial patterns of the population vary in response to changes in the spatial patterns of environmental explanatory variables. Collection of a probability sample from the population provides unbiased estimates of the population parameters using design based estimation. When information is available for the environmental explanatory variables, model based procedures are available that provide more precise estimates of population parameters in some cases. In practice, not all of these environmental explanatory variables will be known. When the spatial coordinates of the population units are available, a spatial model can be used as a surrogate for the unknown, spatially patterned explanatory variables. Design based and model based procedures will be compared for estimating parameters of the population of Acid Neutralizing Capacity (ANC) of lakes in the Adirondack Mountains in New York. Results from the analysis of this population will be used to elucidate some general principles for model based estimation of parameters of spatial populations. Results indicate that using model based estimates of population parameters provide more precise estimates than design based estimates in some cases. In addition, including spatial information as a surrogate for spatially patterned missing covariates improves the precision of the estimates in some cases, the degree to which depends upon the model chosen to represent the spatial pattern. When the probability sample is selected from the spatial population is a stratified sample, differences in stratum variances need to be accounted for when residual spatial covariance estimation is desired for the entire population. This can be accomplished by scaling residuals by their estimated stratum standard deviation functions, and calculating the residual covariance using these scaled residuals. Results here demonstrate that the form of scaling influences the estimated strength of the residual correlation and the estimated correlation range

Handling qualities of a wide-body transport airplane utilizing Pitch Active Control Systems (PACS) for relaxed static stability application

Piloted simulation studies have been conducted to evaluate the effectiveness of two pitch active control systems (PACS) on the flying qualities of a wide-body transport airplane when operating at negative static margins. These two pitch active control systems consisted of a simple 'near-term' PACS and a more complex 'advanced' PACS. Eight different flight conditions, representing the entire flight envelope, were evaluated with emphasis on the cruise flight conditions. These studies were made utilizing the Langley Visual/Motion Simulator (VMS) which has six degrees of freedom. The simulation tests indicated that (1) the flying qualities of the baseline aircraft (PACS off) for the cruise and other high-speed flight conditions were unacceptable at center-of-gravity positions aft of the neutral static stability point; (2) within the linear static stability flight envelope, the near-term PACS provided acceptable flying qualities for static stabilty margins to -3 percent; and (3) with the advanced PACS operative, the flying qualities were demonstrated to be good (satisfactory to very acceptable) for static stabilty margins to -20 percent

Relativistic Broadening of Iron Emission Lines in a Sample of AGN

We present a uniform X-ray spectral analysis of eight type-1 active galactic nuclei (AGN) that have been previously observed with relativistically broadened iron emission lines. Utilizing data from the XMM-Newton European Photon Imaging Camera (EPIC-pn) we carefully model the spectral continuum, taking complex intrinsic absorption and emission into account. We then proceed to model the broad Fe K feature in each source with two different accretion disk emission line codes, as well as a self-consistent, ionized accretion disk spectrum convolved with relativistic smearing from the inner disk. Comparing the results, we show that relativistic blurring of the disk emission is required to explain the spectrum in most sources, even when one models the full reflection spectrum from the photoionized disk.Comment: 50 pages (preprint format), 24 figures. Accepted by Ap

Detecting Compton Reflection and a Broad Iron Line in MCG-5-23-16 with the Rossi X-ray Timing Explorer

We report the detection with the Rossi X-ray Timing Explorer of a Compton reflection signature in the Seyfert galaxy MCG-5-23-16. RXTE also resolves the Fe K-alpha fluorescence line with FWHM ~48,000 km s^{-1}. This measurement provides the first independent confirmation of ASCA detections in Seyfert galaxies of broad Fe K-alpha lines that are thought to be the signature of emission from the inner regions of an accretion disk orbiting a black hole. Under the assumption that reflection arises from an isotropic source located above a neutral accretion disk, and using a theoretical model that accounts for the dependence of the reflected spectrum on inclination angle, we derive a 90% confidence range for the disk inclination of i = 50 to 81 degrees. The large inclination is consistent with that expected from the unified model for MCG-5-23-16 based on its Seyfert 1.9 classification. If we assume that the high-energy cutoff in the incident spectrum lies at energies larger than a few hundred keV, then the equivalent width of the Fe K-alpha line is much larger than predicted for the amount of reflection. This implies either an enhanced iron abundance, a covering factor of reflecting material > 0.5, or a cutoff in the incident spectrum at energies between ~60 and ~200 keV.Comment: Accepted for publication in ApJ, LaTeX. 14 pages including 3 figures, with 1 table as a separate postscript file. Typo corrected in abstrac

Revisiting the sulfur vulcanisation of rubber

Sulfenamide accelerators in combination with zinc oxide activator are used extensively in the sulfur cure systems of a wide range of industrial rubber articles. However, the excessive use of these chemicals has raised major concerns regarding their adverse effect on marine life and human health as well as the environment. Zinc oxide was functionalised with a sulfenamide accelerator in an organic solvent to provide a convenient single material to use as an additive. The effect of the additive on the cure properties of natural rubber was then measured. The aim was to minimize the use of these two chemicals in the cure system and enhance the efficiency of the sulfur vulcanisation of the rubber. Functionalising zinc oxide with the accelerator reduced the excessive use of these chemicals in the cure system. When the cure properties were compared with those of a sulfur cure-based natural rubber compound used to make tyres, the optimum cure time was noticeably shorter and the rate of cure significantly faster despite reducing the use of these two curatives by almost 77 %. All the indications are that the cure efficiency improves considerably when the chemicals in the cure system are reduced

3D printed fluidics with embedded analytic functionality for automated reaction optimisation

Additive manufacturing or ‘3D printing’ is being developed as a novel manufacturing process for the production of bespoke micro- and milliscale fluidic devices. When coupled with online monitoring and optimisation software, this offers an advanced, customised method for performing automated chemical synthesis. This paper reports the use of two additive manufacturing processes, stereolithography and selective laser melting, to create multifunctional fluidic devices with embedded reaction monitoring capability. The selectively laser melted parts are the first published examples of multifunctional 3D printed metal fluidic devices. These devices allow high temperature and pressure chemistry to be performed in solvent systems destructive to the majority of devices manufactured via stereolithography, polymer jetting and fused deposition modelling processes previously utilised for this application. These devices were integrated with commercially available flow chemistry, chromatographic and spectroscopic analysis equipment, allowing automated online and inline optimisation of the reaction medium. This set-up allowed the optimisation of two reactions, a ketone functional group interconversion and a fused polycyclic heterocycle formation, via spectroscopic and chromatographic analysis