Introducing uncertainty of aquifer parameters into an optimization model

A stochastic analysis is made for a previously described groundwater contaminant management model {Peralta and Ward, 1988). The stochastic model is based on incorporating uncertainty of the aquifer parameters transmissivity and effective porosity into the model. This is accomplished by finding the partial derivative of drawdown with respect to each of these parameters using a Taylor series expansion approximation of the Theis equation. Input that is required for the stochastic version is the mean of the transmissivity and effective porosity, the coefficient of variation of the transmissivity and effective porosity, and a reliability level (0%-100%) . The reliability is a measure of the user\u27s required confidence in the model solution. The user wants to be confident, at some probability, that the actual changes in head at pumping wells do not exceed the values calculated by the model, while 1 at the same time, he wants to be confident that actual changes in head at observation wells are at least as great as the calculated values. Thus, equations that are affected by heads at the observation wells are treated differently than equations that are affected by heads at the pumping wells. Optimal strategies are presented to demonstrate sensitivity to changes in standard deviation of aquifer parameters and to changes in reliability level. Tests show that uncertainty of transmissivity affects the optimal pumping more and the final gradient and objective function less than uncertainty of effective porosity. In general, as uncertainty of aquifer parameters increases, optimal pumping values decrease, resulting in a poorer final hydraulic gradient. As the reliability level is increased optimal pumping decreases, again resulting in a poorer final gradient

South Platte River Basin

Presented at Competing interests in water resources - searching for consensus: proceedings from the USCID water management conference held on December 5-7, 1996 in Las Vegas, Nevada.Includes bibliographical references.The potential of demand management as a water management tool in the South Platte River basin is limited by a lack of information regarding existing irrigation practices. A study was conducted to obtain information regarding irrigation water use practices in the basin, to determine the frequency of adoption of water conservation practices, and to relate the frequency of adoption of water conserving measures to various demographic factors. The results were based on 285 responses to a voluntary survey sent to a random sample of 1000 irrigators in eight counties within the basin during the winter of 1995. The survey sought information on farming practices, the adoption of water conservation practices, and grower characteristics. Although disincentives for irrigation water conservation appeared to be significant, the results indicated a high rate of adoption. Seventy-four percent of the survey respondents had adopted some type of water conservation measure on their farms. Adoption of various irrigation water conservation practices was associated most frequently with farm size, but factors such as method of irrigation, water source, knowledge of water law, and level of education were also associated with adoption of one or more conservation measures. Respondents indicated that the primary incentive for adopting water conservation measures was "water conservation." The typical reason for conserving water was to improve existing operations. This suggests that in many instances conservation is being used as a method of extending existing supplies on farms operating under water-short decrees

Immunoregulatory soluble CTLA-4 modifies effector T cell responses in systemic lupus erythematosus

Acknowledgments This work was supported by Arthritis Research UK (Grant no. 19282). We are grateful to Dr. Nick Fluck for his invaluable support in recruiting patients for the study, and Mrs. Vivien Vaughan for her invaluable expertise in recruiting study participants and maintaining ethical documentation.Peer reviewedPublisher PD

Site-Specific Binding Constants for Actinomycin D on DNA Determined from Footprinting Studies

We report site-specific binding constants for the intercalating anticancer drug actinomycin D (Act-D), binding to a 139-base-pair restriction fragment from pBR 322 DNA. The binding constants are derived from analysis of footprinting experiments, in which the radiolabeled 139-mer is cleaved using DNase I, the cleavage products undergo gel electrophoresis, and, from the gel autoradiogram, spot intensities, proportional to amounts of cleaved fragments, are measured. A bound drug prevents DNase I from cleaving at -7 bonds, leading to decreased amounts of corresponding fragments. With the radiolabel on the 3’ end of the noncoding strand (A-label), we measured relative amounts of 54 cleavage products at 25 Act-D concentrations. For cleavage of the 139-mer with the label on the 3’ end of the coding strand (G-label), relative amounts of 43 cleavage products at 11 Act-D concentrations were measured. These measurements give information about - 120 base pairs of the restriction fragment (- 12 turns of the DNA helix); in this region, 14 strong and weak Act-D binding sites were identified. The model used to interpret the footprinting plots is derived in detail. Binding constants for 14 sites on the fragment are obtained simultaneously. It is important to take into account the effect of drug binding at its various sites on the local concentration of probe elsewhere. It is also necessary to include in the model weak as well as strong Act-D sites on the carrier DNA which is present, since the carrier DNA controls the free-drug concentration. As expected, the strongest sites are those with the sequence (all sequences are 5’ - 3’) GC, with TGCT having the highest binding constant, 6.4 X lo6 M-l. Sites having the sequence GC preceded by G are weak binding sites, having binding constants approximately 1 order of magnitude lower than those of the strong sites. Also, the non-GC-containing sequences CCG and CCC bind Act-D with a binding constant comparable to those of the weak GGC sites. The analysis may reveal drug-induced structural changes on the DNA, which are discussed in terms of the mechanism of Act-D binding

Water quality management decisions in Colorado

Submitted to Office of Water Resources Research, U.S. Department of the Interior.Includes bibliographical references.OWRR project no. A-10-COLO

Determination of Netropsin-DNA Binding Constants from Footprinting Data

A theory for deriving drug-DNA site binding constants from footprinting data is presented. Plots of oligonucleotide concentration, as a function of drug concentration, for various cutting positions on DNA are required. It is assumed that the rate of cleavage at each nucleotide position is proportional to the concentration of enzyme at that nucleotide and to the probability that the nucleotide is not blocked by drug. The probability of a nucleotide position not being blocked is calculated by assuming a conventional binding equilibrium for each binding site with exclusions for overlapping sites. The theory has been used to evaluate individual site binding constants for the antiviral agent netropsin toward a 139 base pair restriction fragment of pBR-322 DNA. Drug binding constants, evaluated from footprinting data in the presence of calf thymus DNA and poly(dGdC) as carrier and in the absence of carrier DNA, were determined by obtaining the best fit between calculated and experimental footprinting data. Although the strong sites on the fragment were all of the type (T-A),, the value of the binding constant was strongly sequence dependent. Sites containing the dinucleotide sequence 5\u27-TA-3\u27 were found to have significantly lower binding constants than those without this sequence, suggesting that an adenine-adenine clash produces a DNA structural alteration in the minor groove which discourages netropsin binding to DNA. The errors, scope, and limitations associated with the method are presented and discussed

Surface Electromagnetic Waves on Layered Systems with Damping

The Dispersion Curves, Propagation Distances, and Poynting Vectors of Surface Electromagnetic Waves Propagating on a System of Cu-Cu2O-Air with Variable Film Thickness Have Been Calculated using the Full Dispersion Realation Including Damping. Double-Dip Structure in the Propagation Distance for Intermediately Thick overlayers, the Shifting of One Dip Below ΣTO, and the Presence of the Other Dip at ΣLO Are Explained in Terms of Features of the Dispersion Curve. the Complete Poynting-Vector Calculations Show that Predictions of Field Bunching at ΣLO Are Probably in Error. © 1975 the American Physical Society

Surface Electromagnetic Wave Mode and Field Analysis in a Metal-Metal-Oxide-Air System with Damping

An Explanation is Provided for the Surface Electromagnetic Wave (SEW) Energy Ejection from a Thin Film at the Longitudinal and Transverse Optical-Phonon Frequencies of the Film Material. Field Ratio Calculations Identify Previously Discussed Metal-Metal-Oxide-Air SEW Modes as Those Expected from the Berreman Configuration, and It is Shown that Greenler Technique High-Incidence-Angle-Reflectance Data on the Same System May Be Similarly Interpreted. © 1976 the American Physical Society

Cloudtop

Even as users rely more on the web for their computing needs, they continue to depend on a desktop-like area for quick access to in-use resources. The traditional desktop is file-centric and prone to clutter, making it suboptimal for use in a web-dominated world. This paper introduces Cloudtop, a browser plugin that offers a lightweight workplace for temporary items, optimized around the idea that its contents originate from and will ultimately return to the web. Cloudtop improves upon the desktop by 1) implementing a simple, time-based notebook metaphor for managing clutter, 2) capturing and bundling extensible metadata for web resources, and 3) providing a platform for greater interface uniformity across sites