Investigation of the nonlocal coherent-potential approximation

Recently the nonlocal coherent-potential approximation (NLCPA) has been introduced by Jarrell and Krishnamurthy for describing the electronic structure of substitutionally disordered systems. The NLCPA provides systematic corrections to the widely used coherent-potential approximation (CPA) whilst preserving the full symmetry of the underlying lattice. Here an analytical and systematic numerical study of the NLCPA is presented for a one-dimensional tight-binding model Hamiltonian, and comparisons with the embedded cluster method (ECM) and molecular coherent potential approximation (MCPA) are made.Comment: 18 pages, 5 figure

CONTRACTS-LAW APPLYING TO GOVERNMENT CONTRACTS-PENALTY CLAUSES

Petitioner contracted with the Federal Surplus Commodities Corporation of the United States Department of Agriculture to supply dried eggs under the Lend-Lease Act of 1941. Delivery was to be made on the first day of a 10-day period within which the F. S. C. C. will accept delivery. The ten-day period started on May 18, 1942, and the eggs were to be inspected and ready for shipment on that date. Two provisions for liquidated damages were stated: one for delays in delivery, the other for failure to have the products inspected and ready on the specified dare. Petitioner failed to have the products ready by May 18, but they were ready before delivery was requested. The government claimed damages on the strength of the second liquidated damages provision, and was upheld in the Court of Claims. On certiorari, held, reversed. The provision was for a penalty and therefore void. Four justices dissented. Priebe & Sons, Inc. v. United States, (U.S. 1947) 68 S.Ct. 123·

Effects of short-range order on the electronic structure of disordered metallic systems

For many years the Korringa-Kohn-Rostoker coherent-potential approximation (KKR-CPA) has been widely used to describe the electronic structure of disordered systems based upon a first-principles description of the crystal potential. However, as a single-site theory the KKR-CPA is unable to account for important environmental effects such as short-range order (SRO) in alloys and spin fluctuations in magnets, amongst others. Using the recently devised KKR-NLCPA (where NL stands for nonlocal), we show how to remedy this by presenting explicit calculations for the effects of SRO on the electronic structure of the bcc Cu_{50}Zn_{50} solid solution.Comment: 8 pages, 6 figures, Revised versio

Bibliometrics Seminar

On 22 May 2014, the University Library System, University of Pittsburgh, held a Bibliometrics Seminar, a program detailing several research library service models for support of research evaluation and assessment. Three of the featured speakers--from academic libraries in the USA (Mayo), the UK (Rowlands), and Australia (Thomas)--discuss the development and operation of such services in their organizations, noting the drivers for development, the process of setting up the service, and the impact of the service on both the library and the institution. A faculty colleague (Larsen) talks about his needs for research assessment as both a senior researcher and university manager. Presentation 1: "Providing a Library Metrics Service: a perspective from an academic library within an Australian University" by Dr. Amberyn Thomas, Manager, Scholarly Publications, University of Queensland, Australia. Presentation 2: "Library Research Services at the University of Leicester, UK" by Ian Rowlands, Research Services Manager and University Bibliometrician, University of Leicester. Presentation 3: "Research Connection: Expertise to Advance Your Success" by Alexa Mayo, MLS AHIP, Health Sciences and Human Services Library, University of Maryland, Baltimore. Presentation 4: "Bibliometric Research Services - an iSchool Dean's Perspective" by Ronald L. Larsen, Dean and Professor, School of Information Sciences, University of Pittsburgh. The program for the event and a recording of the presentations are also included

PIC Simulations of the Temperature Anisotropy-Driven Weibel Instability: Analyzing the perpendicular mode

An instability driven by the thermal anisotropy of a single electron species is investigated in a 2D particle-in-cell (PIC) simulation. This instability is the one considered by Weibel and it differs from the beam driven filamentation instability. A comparison of the simulation results with analytic theory provides similar exponential growth rates of the magnetic field during the linear growth phase of the instability. We observe in accordance with previous works the growth of electric fields during the saturation phase of the instability. Some components of this electric field are not accounted for by the linearized theory. A single-fluid-based theory is used to determine the source of this nonlinear electric field. It is demonstrated that the magnetic stress tensor, which vanishes in a 1D geometry, is more important in this 2-dimensional model used here. The electric field grows to an amplitude, which yields a force on the electrons that is comparable to the magnetic one. The peak energy density of each magnetic field component in the simulation plane agrees with previous estimates. Eddy currents develop, which let the amplitude of the third magnetic field component grow, which is not observed in a 1D simulation.Comment: accepted by Plasma Physics and Controlled Fusio

Potent antiviral agents fail to elicit genetically-stable resistance mutations in either enterovirus 71 or Coxsackievirus A16

Enterovirus 71 (EV71) and Coxsackievirus A16 (CVA16) are the two major causative agents 13 of hand, foot and mouth disease (HFMD), for which there are currently no licenced 14 treatments. Here, the acquisition of resistance towards two novel capsid-binding compounds, 15 NLD and ALD, was studied and compared to the analogous compound GPP3. During serial 16 passage, EV71 rapidly became resistant to each compound and mutations at residues I113 17 and V123 in VP1 were identified. A mutation at residue 113 was also identified in CVA16 18 after passage with GPP3. The mutations were associated with reduced thermostability and 19 were rapidly lost in the absence of inhibitors. In silico modelling suggested that the mutations 20 prevented the compounds from binding the VP1 pocket in the capsid. Although both viruses 21 developed resistance to these potent pocket-binding compounds, the acquired mutations were 22 associated with large fitness costs and reverted to WT phenotype and sequence rapidly in the 23 absence of inhibitors. The most effective inhibitor, NLD, had a very large selectivity index, 24 showing interesting pharmacological properties as a novel anti-EV71 agent

The backwards comparability of wrist worn GENEActiv and waist worn ActiGraph accelerometer estimates of sedentary time in children

Objectives: To examine the backward comparability of a range of wrist-worn accelerometer estimates of sedentary time (ST) with ActiGraph 100 count∙min-1 waist ST estimates. Design: Cross-sectional, secondary data analysis Method: One hundred and eight 10-11-year-old children (65 girls) wore an ActiGraph GT3X+ accelerometer (AG) on their waist and a GENEActiv accelerometer (GA) on their non-dominant wrist for seven days. GA ST data were classified using a range of thresholds from 23-56 mg. ST estimates were compared to AG ST 100 count∙min-1 data. Agreement between the AG and GA thresholds was examined using Cronbach’s alpha, intraclass correlation coefficients (ICC), limits of agreement (LOA), Kappa values, percent agreement, mean absolute percent error (MAPE) and equivalency analysis. Results: Mean AG total ST was 492.4 minutes over the measurement period. Kappa values ranged from 0.31-0.39. Percent agreement ranged from 68-69.9%. Cronbach’s alpha values ranged from 0.88-0.93. ICCs ranged from 0.59-0.86. LOA were wide for all comparisons. Only the 34 mg threshold produced estimates that were equivalent at the group level to the AG ST 100 count∙min-1 data though sensitivity and specificity values of ~64% and ~74% respectively were observed. Conclusions: Wrist-based estimates of ST generated using the 34 mg threshold are comparable with those derived from the AG waist mounted 100 count∙min-1 threshold at the group level. The 34 mg threshold could be applied to allow group-level comparisons of ST with evidence generated using the ActiGraph 100 count∙min-1 method though it is important to consider the observed sensitivity and specificity results when interpreting findings