Early Results on Radioactive Background Characterization for Sanford Laboratory and DUSEL Experiments

Measuring external sources of background for a deep underground laboratory at the Homestake Mine is an important step for the planned low-background experiments. The naturally occurring $\gamma$-ray fluxes at different levels in the Homestake Mine are studied using NaI detectors and Monte Carlo simulations. A simple algorithm is developed to convert the measured $\gamma$-ray rates into $\gamma$-ray fluxes. A good agreement between the measured and simulated $\gamma$-ray fluxes is achieved with the knowledge of the chemical composition and radioactivity levels in the rock. The neutron fluxes and $\gamma$-ray fluxes are predicted by Monte Carlo simulations for different levels including inaccessible levels that are under construction for the planned low background experiments.Comment: 16 pages, 2 figures, and 9 table

Quantifying and resolving multiple vector transformants in S. cerevisiae plasmid libraries

<p>Abstract</p> <p>Background</p> <p>In addition to providing the molecular machinery for transcription and translation, recombinant microbial expression hosts maintain the critical genotype-phenotype link that is essential for high throughput screening and recovery of proteins encoded by plasmid libraries. It is known that <it>Escherichia coli </it>cells can be simultaneously transformed with multiple unique plasmids and thusly complicate recombinant library screening experiments. As a result of their potential to yield misleading results, bacterial multiple vector transformants have been thoroughly characterized in previous model studies. In contrast to bacterial systems, there is little quantitative information available regarding multiple vector transformants in yeast. <it>Saccharomyces cerevisiae </it>is the most widely used eukaryotic platform for cell surface display, combinatorial protein engineering, and other recombinant library screens. In order to characterize the extent and nature of multiple vector transformants in this important host, plasmid-born gene libraries constructed by yeast homologous recombination were analyzed by DNA sequencing.</p> <p>Results</p> <p>It was found that up to 90% of clones in yeast homologous recombination libraries may be multiple vector transformants, that on average these clones bear four or more unique mutant genes, and that these multiple vector cells persist as a significant proportion of library populations for greater than 24 hours during liquid outgrowth. Both vector concentration and vector to insert ratio influenced the library proportion of multiple vector transformants, but their population frequency was independent of transformation efficiency. Interestingly, the average number of plasmids born by multiple vector transformants did not vary with their library population proportion.</p> <p>Conclusion</p> <p>These results highlight the potential for multiple vector transformants to dominate yeast libraries constructed by homologous recombination. The previously unrecognized prevalence and persistence of multiply transformed yeast cells have important implications for yeast library screens. The quantitative information described herein should increase awareness of this issue, and the rapid sequencing approach developed for these studies should be widely useful for identifying multiple vector transformants and avoiding complications associated with cells that have acquired more than one unique plasmid.</p

Robust Estimator-Based Safety Verification: A Vector Norm Approach

In this paper, we consider the problem of verifying safety constraint satisfaction for single-input single-output systems with uncertain transfer function coefficients. We propose a new type of barrier function based on a vector norm. This type of barrier function has a measurable upper bound without full state availability. An identifier-based estimator allows an exact bound for the uncertainty-based component of the barrier function estimate. Assuming that the system is safe initially allows an exponentially decreasing bound on the error due to the estimator transient. Barrier function and estimator synthesis is proposed as two convex sub-problems, exploiting linear matrix inequalities. The barrier function controller combination is then used to construct a safety backup controller. And we demonstrate the system in a simulation of a 1 degree-of-freedom human-exoskeleton interaction.Comment: 6 pages, 5 figures. Accepted for publication at the 2020 American Control Conference. Copyright IEEE 202

Farmer Cooperatives: Commercial Farmer Members and Use

Seventy-eight percent of commercial farmers were either members or nonmember patrons of marketing/farm supply cooperatives in 1986 compared with more than 76 percent in 1980. From 1980 to 1986, the percentage of commercial farmers who were members of cooperatives increased from 65 to 66 percent. Nonmember patrons held steady at 12 percent. The biggest change was an increase in percent of members among commercial farmers with sales of $500,000 and over. Members among this group increased from 56 percent in 1980 to 69 percent in 1986. The percentage of commercial farmers with multiple memberships increased and the percentage of farmers with inactive memberships decreased. The percentage using cooperatives for marketing and for purchasing increased. Forty-nine percent used a cooperative for marketing, and 71 percent used a cooperative to purchase farm supplies in 1986. Data for the study were obtained from surveys by the National Agricultural Statistics Service (formerly Statistical Reporting Service), U.S. Department of Agriculture.Farmer cooperatives, marketing cooperatives, farm supply cooperatives, cooperative members, commercial farmer, Agribusiness,

PQChPT with Staggered Sea and Valence Ginsparg-Wilson Quarks: Vector Meson Masses

We consider partially quenched, mixed chiral perturbation theory with staggered sea and Ginsparg-Wilson valence quarks in order to extract a chiral-continuum extrapolation expression for the vector meson mass up to order O(a^2), at one-loop level. Based on general principles, we accomplish the task without explicitly constructing a sophisticated, heavy vector meson chiral Lagrangian.Comment: 12 pages, 1 figure, REVTe