Examining the Effect of Pore Size Distribution and Shape on Flow through Unsaturated Peat using Computer Tomography

The hydraulic conductivity of unsaturated peat soil is controlled by the air-filled porosity, pore size and geometric distribution as well as other physical properties of peat materials. This study investigates how the size and shape of pores affects the flow of water through peat soils. In this study we used X-ray Computed Tomography (CT), at 45μm resolution under 5 specific soil-water pressure head levels to provide 3-D, high-resolution images that were used to detect the inner pore structure of peat samples under a changing water regime. Pore structure and configuration were found to be irregular, which affected the rate of water transmission through peat soils. The 3-D analysis suggested that pore distribution is dominated by a single large pore-space. At low pressure head, this single large air-filled pore imparted a more effective flowpath compared to smaller pores. Smaller pores were disconnected and the flowpath was more tortuous than in the single large air-filled pore, and their contribution to flow was negligible when the single large pore was active. We quantify the pore structure of peat soil that affects the hydraulic conductivity in the unsaturated condition, and demonstrate the validity of our estimation of peat unsaturated hydraulic conductivity by making a comparison with a standard permeameter-based method. Estimates of unsaturated hydraulic conductivities were made for the purpose of testing the sensitivity of pore shape and geometry parameters on the hydraulic properties of peats and how to evaluate the structure of the peat and its affects on parameterization. We also studied the ability to quantify these factors for different soil moisture contents in order to define how the factors controlling the shape coefficient vary with changes in soil water pressure head. The relation between measured and estimated unsaturated hydraulic conductivity at various heads shows that rapid initial drainage, that changes the air-filled pore properties, creates a sharp decline in hydraulic conductivity. This is because the large pores readily lose water, the peat rapidly becomes less conductive and the flow path among pores, more tortuous

When Taint Teams Go Awry: Laundering Unconstitutional Violations of the Fourth Amendment

In this Article, we examine the legal landscape in which taint teams operate, why taint teams are constitutionally problematic, and propose a solution to protect the attorney-client privilege. In Part I, we will first describe what taint teams are supposed to protect—attorney-client privilege. Next, we review how a taint team gets its documents to review, namely the doctrine surrounding (secret) search warrants. Part I ends with a non exhaustive summary of remedies available when attorney-client privilege is violated during searches. In Part II, we explain the current policies and practices surrounding taint teams, including sources of procedure for taint teams and the use of warrants for electronic information. Part II concludes with a summary of the lopsided pre-2019 split in authority on the use of taint teams in federal criminal prosecutions. Part III is devoted to examining the constitutional and practical shortcomings of the current formulation of taint teams. Using a 2019 case that forcefully criticized the use of taint teams, we explore constitutional issues under the Bill of Rights and separation-of-powers doctrine. Part III concludes with a discussion of the federal government’s proposed solution to these judicially identified deficiencies and an explanation of why that solution is wholly inadequate. In Part IV, we review a series of possible solutions already in practice in various jurisdictions and then propose a new solution to resolve the constitutional issues of taint teams and protect attorney-client privilege. Specifically, we propose a new structure that locates privilege-review teams as a function within the federal public defender’s office, where judicial officers make recommended privilege determinations subject to judicial review. We explain that this solves the Fourth Circuit’s constitutional criticisms while simultaneously recognizing the need to review potentially privileged materials by someone other than the target of an investigation

MODELING DISPERSAL OF YELLOW STARTHISTLE IN THE CANYON GRASSLANDS OF NORTH CENTRAL IDAHO

Yellow starthistle is an invasive plant species that reduces productivity and plant diversity within the canyon grasslands of Idaho. Early detection of yellow starthistle and predicting its spread have important managerial implications that could greatly reduce the economic/environmental losses due to this weed. The spread of an invasive plant species depends on its ability to reproduce and disperse seed into new areas. Typically, information on the factors that directly affect a plant’s ability to reproduce and subsequently disperse seed is not available or difficult to obtain. Alternatively, topographic factors, such as slope and aspect as well as competitive correlates such as vegetation indices related to plant community biomass could be used to model plant survival and seed movement. In this research, several spatial network models incorporating these variables were considered for the prediction of yellow starthistle dispersal. Models will differed in their assessment of plant movement costs, which can be separated into two processes, survival to reproduction and seed dispersal. The candidate models were evaluated based on their predictive ability and biological relevance. Topographical variables, slope and aspect, were found to be significant contributors to yellow starthistle dispersal models, whereas vegetation indices did not improve the prediction process. The optimal model was applied to an area in central Idaho for predicting the dispersal of yellow starthistle in 1987 given a known 1981 infestation

General Aviation Trends in the European Market Memorandum Report

In 1969, as western Europe was becoming a common market, significant economic growth was projected. His Highness, The Aga Kahn requested that Economics Research Associates (ERA) perform a memorandum report and forecast the trends for private aviation potentials in Europe over the decade of the 1970s. The resulting report by ERA reviews the history of European aviation, current and future economic trends in the common European market area as these pertain to the growth of private aviation, advantages and disadvantages involved in noncommercial flying, and future trends in private aviation. Data was gathered from such sources as aviation publications, interviews with persons connected with private aviation, and market studies and projections of commercial organizations. The report includes the following sections: 1) introduction, 2) summary and conclusions, 3) the western European economy, 4) general aviation, 5) general aviation and future trends in aviation design, 6) impact of general aviation on tourism. The report includes four tables

Formation of a rotating hole from a close limit head-on collision

Realistic black hole collisions result in a rapidly rotating Kerr hole, but simulations to date have focused on nonrotating final holes. Using a new solution of the Einstein initial value equations we present here waveforms and radiation for an axisymmetric Kerr-hole-forming collision starting from small initial separation (the ``close limit'' approximation) of two identical rotating holes. Several new features are present in the results: (i) In the limit of small separation, the waveform is linear (not quadratic) in the separation. (ii) The waveforms show damped oscillations mixing quasinormal ringing of different multipoles.Comment: 4 pages, 4 figures, submitted to PR

Effects of polydispersity on PGSE NMR coherence features

Real systems always contain some degree of polydispersity and yet the effects of this real and very important problem have not been studied in great detail in NMR diffusion experiments. The effects of polydispersity become even less clear when we are outside the short gradient pulse (SGP) limit (which we generally are). Here we investigate the effects of polydispersity, in the form of a Gaussian distribution of characteristic distances, on the coherence features of PGSE NMR experiments of a model system. Characteristic pore sizes were determined from the coherence features and compared to characteristic distances determined from Fourier transforms of the second derivative