Conference on Alaskan placer mining, focus: gold recovery systems

Alaska Miners' Association and the School of Mineral Industry, University of Alaska, Fairbanks conference proceedings of the Alaskan Placer Mining conference on Gold Recovery Systems

The electron density is smooth away from the nuclei

We prove that the electron densities of electronic eigenfunctions of atoms and molecules are smooth away from the nuclei.Comment: 16 page

A new approach to the modelling of local defects in crystals: the reduced Hartree-Fock case

This article is concerned with the derivation and the mathematical study of a new mean-field model for the description of interacting electrons in crystals with local defects. We work with a reduced Hartree-Fock model, obtained from the usual Hartree-Fock model by neglecting the exchange term. First, we recall the definition of the self-consistent Fermi sea of the perfect crystal, which is obtained as a minimizer of some periodic problem, as was shown by Catto, Le Bris and Lions. We also prove some of its properties which were not mentioned before. Then, we define and study in details a nonlinear model for the electrons of the crystal in the presence of a defect. We use formal analogies between the Fermi sea of a perturbed crystal and the Dirac sea in Quantum Electrodynamics in the presence of an external electrostatic field. The latter was recently studied by Hainzl, Lewin, S\'er\'e and Solovej, based on ideas from Chaix and Iracane. This enables us to define the ground state of the self-consistent Fermi sea in the presence of a defect. We end the paper by proving that our model is in fact the thermodynamic limit of the so-called supercell model, widely used in numerical simulations.Comment: Final version, to appear in Comm. Math. Phy

Geochemical-geophysical investigations, Fairbanks district

Trace element distribution in a subarctic valley in the Cleary Hill area of the Fairbanks gold district has been studied. Zinc and arsenic have been found excellent pathfinder elements for auriferous deposits. Methods of analysis for copper, lead, zinc, molybdenum, silver and arsenic as well as heavy metals are discussed. The University of Alaska method #2 has been improved, Terrain, slope, and frozen ground have little effect upon the distribution of trace elements associated with the Cleary H i l l vein. A new method for the determination of zinc using dilute acid is proposed. Analysis of geochemical data by trend surface procedures proved effective for localization of anomalies

Recruiting VR Troopers: Bringing Introductory Programming Projects to Life in Virtual Reality

Classes in introductory programming often focus on solving small, succinct problems that can typically be completed in few lines of source code. While useful for learning the basics of algorithm implementation and language syntax, this method suggests to learners that all programming problems exist in isolation and are self-contained. In contrast, most programming assignments faced by fresh graduates are large in scope and require use of many pre-built libraries and extensions. As a result, students are not entirely prepared to write code that will function within a larger system. To address this problem, an introductory C programming course at Valparaiso University has explored the use of virtual reality as a means to motivate students to have fun while practicing coding skills and showcase the power of working within constraints of a complex system. Students are provided a brief introduction to the OpenGL 3D graphics framework and then asked to design a small, optionally animated, scene using their current knowledge of the C programming language. Later in the semester, these same students are brought into a VisCube Virtual Reality system to experience their scenes in a fully immersive environment. The VisCube uses eight rendering paths and stereo displays to generate a 3D scene in a 10’x8’x6’ cube. This exercise serves to show students that even a simple scene can then easily expanded to display in a virtual reality environment. We discuss the project assignment and student impacts using assessment and provide a brief discussion of how this can be adapted to facilities with other viualization capabilities

Green fluorescent protein-based assays for high-throughput functional characterization and ligand-binding studies of biotin protein ligase

In E. coli and other prokaryotes such as Staphylococcus aureus, and Mycobacterium tuberculosis, biotin protein ligase (BirA) is an emerging drug target as it is the sole enzyme capable of biotin transfer onto the BCCP subunit of ACC. There is currently a gap in simple yet efficient assays for rapidly identifying and characterising inhibitors targeting BirA. We present for the first time the development and validation of a simple and reliable DSF-GTP assay for the high-throughput screening of BirA: ligand interactions using a new GFP-tagged BirA of E. coli. In addition, we developed a new GFP-based biotinylation activity assay taking advantage of a GFP tethered with an AviTag. The data obtained with these assays revealed new insights into how the binding of individual or combinations of ligands affect the overall thermal stability and affinity of BirA. The DSF-GTP assay has a Z' value of 0.785 that makes it an excellent tool for future high-throughput screening of inhibitory compounds

Derivation of the cubic NLS and Gross-Pitaevskii hierarchy from manybody dynamics in d=3d=3 based on spacetime norms

We derive the defocusing cubic Gross-Pitaevskii (GP) hierarchy in dimension $d=3$, from an $N$-body Schr\"{o}dinger equation describing a gas of interacting bosons in the GP scaling, in the limit $N\rightarrow\infty$. The main result of this paper is the proof of convergence of the corresponding BBGKY hierarchy to a GP hierarchy in the spaces introduced in our previous work on the well-posedness of the Cauchy problem for GP hierarchies, \cite{chpa2,chpa3,chpa4}, which are inspired by the solutions spaces based on space-time norms introduced by Klainerman and Machedon in \cite{klma}. We note that in $d=3$, this has been a well-known open problem in the field. While our results do not assume factorization of the solutions, consideration of factorized solutions yields a new derivation of the cubic, defocusing nonlinear Schr\"odinger equation (NLS) in $d=3$.Comment: 44 pages, AMS Late

Building Full-Service Schools: Lessons Learned in the Development of Interagency Collaboratives

Although the history of clinical-school-eommunity collaboration can be traced back to the end of the 19th century, the full-service school movement represents a new era in the quest for more effective ways to deliver human services to children. As awareness that school systems alone cannot address the social problems affecting millions of children, the concept of full-service schools has been embraced as a potential solution to service delivery problems affecting children living in high-risk environments. Built on shared commitment to positive child development, full-service schools represent an effort to make human service systems partners in the educational process, while simultaneously making school systems partners in the delivery of human services (Adelman & Taylor, 1999; Dryfoos, 1994a, 1995/1997/1998; Morrill, 1992)

Flexibility of KorA, a plasmid-encoded, global transcription regulator, in the presence and the absence of its operator

The IncP (Incompatibility group P) plasmids are important carriers in the spread of antibiotic resistance across Gram-negative bacteria. Gene expression in the IncP-1 plasmids is stringently controlled by a network of four global repressors, KorA, KorB, TrbA and KorC interacting cooperatively. Intriguingly, KorA and KorB can act as co-repressors at varying distances between their operators, even when they are moved to be on opposite sides of the DNA. KorA is a homodimer with the 101-amino acid subunits, folding into an N-terminal DNA-binding domain and a C-terminal dimerization domain. In this study, we have determined the structures of the free KorA repressor and two complexes each bound to a 20-bp palindromic DNA duplex containing its consensus operator sequence. Using a combination of X-ray crystallography, nuclear magnetic resonance spectroscopy, SAXS and molecular dynamics calculations, we show that the linker between the two domains is very flexible and the protein remains highly mobile in the presence of DNA. This flexibility allows the DNA-binding domains of the dimer to straddle the operator DNA on binding and is likely to be important in cooperative binding to KorB. Unexpectedly, the C-terminal domain of KorA is structurally similar to the dimerization domain of the tumour suppressor p53

Selective protein unfolding: a universal mechanism of action for the development of irreversible inhibitors

High-throughput differential scanning fluorimetry of GFP-tagged proteins (HT-DSF-GTP) was applied for the identification of novel enzyme inhibitors acting by a mechanism termed: selective protein unfolding (SPU). Four different protein targets were interrogated with the same library to identify target-selective hits. Several hits selectively destabilized bacterial biotin protein ligase. Structure–activity relationship data confirmed a structure-dependent mechanism of protein unfolding. Simvastatin and altenusin were confirmed to irreversibly inactivate biotin protein ligase. The principle of SPU combined with HT-DSF-GTP affords an invaluable and innovative workflow for the identification of new inhibitors with potential applications as antimicrobials and other biocides