Noise and disturbance in quantum measurements: an information-theoretic approach

We introduce information-theoretic definitions for noise and disturbance in quantum measurements and prove a state-independent noise-disturbance tradeoff relation that these quantities have to satisfy in any conceivable setup. Contrary to previous approaches, the information-theoretic quantities we define are invariant under relabelling of outcomes, and allow for the possibility of using quantum or classical operations to `correct' for the disturbance. We also show how our bound implies strong tradeoff relations for mean square deviations.Comment: v3: to appear on PRL (some issues fixed, supplemental material expanded). v2: replaced with submitted version; 5 two-column pages + 6 one-column pages + 3 figures; one issue corrected and few references added. v1: 17 pages, 3 figure

Sign learning kink-based (SiLK) quantum Monte Carlo for molecular systems

The Sign Learning Kink (SiLK) based Quantum Monte Carlo (QMC) method is used to calculate the ab initio ground state energies for multiple geometries of the H$_{2}$O, N$_2$, and F$_2$ molecules. The method is based on Feynman's path integral formulation of quantum mechanics and has two stages. The first stage is called the learning stage and reduces the well-known QMC minus sign problem by optimizing the linear combinations of Slater determinants which are used in the second stage, a conventional QMC simulation. The method is tested using different vector spaces and compared to the results of other quantum chemical methods and to exact diagonalization. Our findings demonstrate that the SiLK method is accurate and reduces or eliminates the minus sign problem.Comment: 20 pages, 9 figures, to appear in the Journal of Chemical Physic

Exploring Student Persistence in STEM Programs: A Motivational Model

To address continually decreasing enrollment and rising attrition in post-secondary STEM degree (science, technology, engineering, and mathematics) programs, particularly for women, the present study examines the utility of motivation and emotion variables to account for persistence and achievement in science in male and female students transitioning from high school to junior college. Consistent with self-determination theory (Deci & Ryan, 2012) and achievement-goal theory (Senko, Hulleman, & Harackiewicz, 2011),structural equation modelling based on data from 1,309 students from four English-language CEGEPs showed students’ achievement goals, self-efficacy, and perceived autonomy support to impact intrinsic motivation, emotions, and achievement that, in turn, predicted persistence in the science domain

Mutation of a Highly Conserved Arginine in Motif IV of Escherichia coli DNA Helicase II Results in an ATP-binding Defect

A site-directed mutation in motif IV of Escherichia coli DNA helicase II (UvrD) was generated to examine the functional significance of this region. The highly conserved arginine at position 284 was replaced with alanine to construct UvrD-R284A. The ability of the mutant allele to function in methyl-directed mismatch repair and UvrABC-mediated nucleotide excision repair was examined by genetic complementation assays. The R284A substitution abolished function in both DNA repair pathways. To identify the biochemical defects responsible for the loss of biological function, UvrD-R284A was purified to apparent homogeneity, and its biochemical properties were compared with wild-type UvrD. UvrD-R284A failed to unwind a 92-base pair duplex region and was severely compromised in unwinding a 20-base pair duplex region. The Km of UvrD-R284A for ATP was significantly greater than 3 mM compared with 80 microM for UvrD. A large decrease in ATP binding was confirmed using a nitrocellulose filter binding assay. These data suggested that the R284A mutation severely reduced the affinity of helicase II for ATP. The reduced unwinding activity and loss of biological function of UvrD-R284A was probably the result of decreased affinity for ATP. These results implicate motif IV of superfamily I helicases in nucleotide binding and represent the first characterization of a helicase mutation outside motifs I and II that severely impacted the Km for ATP

Marshall University Music Department Presents Bluetrane, Faculty Jazz Ensemble, Featuring, Ed Bingham, saxophone, Mike Stroeher, trombone, Steve Hall, percussion Sean Parsons, piano, Martin Saunders, trumpet, Mark Zanter, guitar

https://mds.marshall.edu/music_perf/1498/thumbnail.jp

The Escherichia coli MutL Protein Physically Interacts with MutH and Stimulates the MutH-associated Endonuclease Activity

All possible pairwise combinations of UvrD, MutL, MutS, and MutH were tested using the yeast two-hybrid system to identify potential interactions involving mismatch repair proteins. A two-hybrid screen previously identified a physical interaction between MutL and UvrD. Although several other known interactions were not observed, a novel interaction between MutL and MutH was detected. A series of truncations from the NH2 and COOH termini of MutL demonstrated that the COOH-terminal 218 amino acids were sufficient for the two-hybrid interaction with MutH. Removal of a small number of residues from either the NH2 or COOH termini of MutH eliminated the two-hybrid interaction with MutL. Protein affinity chromatography experiments confirmed that MutL, but not MutS, physically associates with MutH. Furthermore, MutL greatly stimulated the d(GATC)-specific endonuclease activity of MutH in the absence of MutS and a mispaired base. Stimulation of the MutH-associated endonuclease activity by MutL was dependent on ATP binding but not ATP hydrolysis. Further stimulation of this reaction by MutS required the presence of a DNA mismatch and a hydrolyzable form of ATP. These results suggest that MutL activates the MutH-associated endonuclease activity through a physical interaction during methyl-directed mismatch repair in Escherichia coli

Relating PH and Ion Release from Ga2O3-Na 2O-CaO-ZnO-SiO2 Bioactive Glasses

Three glasses were designed for this study, including one Ga-free glass (Control), and two Ga-containing glasses (TGa-1, TGa-2). In the Ga-containing glasses, Ga2O3 is included at the expense of ZnO. This study focuses on the relation between pH and ion concentration present in solution in which these bioactive glasses have been submerged for periods of 1, 7, and 14 days. © 2013 IEEE

The Structural Characterization of Ga 2O 3-Na 2O-CaO-ZnO-SiO 2 Bioactive Glasses

The characterization of bioactive glasses in which zinc (Zn) has been incrementally replaced by gallium (Ga). © 2012 IEEE