Magnetic incommensurability in pp-type cuprate perovskites

For the superconducting phase with a d-wave order parameter and zero temperature the magnetic susceptibility of the t-J model is calculated using the Mori projection operator technique. Conditions for the appearance of an incommensurate magnetic response below the resonance frequency are identified. A fast decay of the tails of the hole coherent peaks and a weak intensity of the hole incoherent continuum near the Fermi level are enough to produce an incommensurate response using different hole dispersions established for $p$-type cuprates, in which such response was observed. In this case, the nesting of the itinerant-electron theory or the charge modulation of the stripe theory is unnecessary for the incommensurability. The theory reproduces the hourglass dispersion of the susceptibility maxima with their location in the momentum space similar to that observed experimentally. The upper branch of the dispersion stems from the excitations of localized spins, while the lower one is due to the incommensurate maxima of their damping. The narrow and intensive resonance peak arises if the frequency of these excitations at the antiferromagnetic momentum lies below the edge of the two-fermion continuum; otherwise the maximum is broad and less intensive.Comment: 22 pages, 7 figure

Markets and diversity : annotated bibliography

This document represents the first and second phase of a project to build an inventory of key literature on the subject of ‘markets and diversity’. The first phase involved a literature search and compilation of 100 bibliographic items. The second phase involved the annotation of 40 of these items. The third phase consisted of a synthetic overview of this literature, and was published as an MMG Working Paper 11-03, ‘Markets and Diversity: An Overview’. The literature was compiled using various databases, web search tools, and a range of search terms. I combined search terms indicating the type or region of markets (i.e. ‘Bazaar’, ‘souq’, ‘fea’, ‘feira’, ‘open-air market’, ‘open market’, ‘farmer’s market’, ‘street market’) with indicators of diversity (i.e. ‘ethnic’, ‘immigrant’, ‘class’, ‘race’, ‘gender’). Other more specific thematic terms (i.e. ‘cosmopolitanism’, ‘entrepreneurship’, ‘inclusion’, ‘interaction’, ‘Orientalism’ and so on) were also used. There were no restrictions as to time period, region, or publishing date, although the emphasis is on recent work in the field. The entries focusing most specifically on diverse markets were selected for more thorough annotation. Section I of this paper presents the bibliographic abstracts, organized by research theme (please see WP 11-03 for a detailed explanation). This section includes only published abstracts. Where no abstract was supplied, I provide a brief summary of the entry. Note: the research themes are not mutually exclusive, and the abstracts may appear under more than one heading. An * preceding an entry indicates that the source is annotated in section II. Section II contains the annotations, organized alphabetically, by the author’s last name. For each of these annotations, I provide the 1) disciplinary background of the author(s) and, where possible, their institution; 2) research questions; 3) conceptual framework; 4) group studied; 5) methodology; 6) findings; and 7) significance of the research to the field. In Section III, the references are organized by region (I use the United Nations regional scheme)

An examination of the processes by which construal level affects the implicit evaluation of goal relevant stimuli.

Previous research has found that construal level—how abstractly or concretely people represent events—can impact implicit evaluations. Abstract high-level construal (vs. concrete low-level construal) promotes evaluative responses consistent with global (strongly held, long-term) rather than local (short-term, situational) goals. It remains unclear by what cognitive process(es) this occurs. In this paper, we examine two possibilities. High-level construal might enhance the unintended influence of activated evaluative associations or facilitate the detection and implementation of intentional responses. To examine these possibilities, the current study applies a multinomial processing tree model to data from Fujita and Han (2009). Results suggest that high-level construal facilitates goal-consistent evaluations by increasing both the unintentional influence of activated goal-consistent positive associations and the intentional detection of and implementation of accurate responding to goal-relevant stimuli. These findings extend our understanding of how construal level promotes goal consistent evaluations

Improved precision with Hologic Apex software.

UnlabelledThe precision of Hologic Apex v2.0 analysis software is significantly improved from Hologic Delphi v11.2 software and is comparable to GE Lunar Prodigy v7.5 software. Apex and Delphi precisions were, respectively, 1.0% vs. 1.2% (L1-L4 spine), 1.l % vs. 1.3% (total femur), 1.6% vs. 1.9% (femoral neck), and 0.7% vs. 0.9% (dual total femur).IntroductionPrecision of bone mineral density (BMD) measurements by dual-energy X-ray absorptiometry (DXA) is known to vary by manufacturer, model, and technologist. This study evaluated the precision of three analysis versions: Apex v2.0 and Delphi v11.2 (Hologic, Inc.), and Prodigy v7.5 (GE Healthcare, Inc.) independent of technologist skill.MethodsDuplicate spine and dual hip scans on 90 women were acquired on both Delphi and Prodigy DXA systems at three clinics. BMD measures were converted to standardized BMD (sBMD) units. Precision errors were described as a root-mean-square (RMS) standard deviations and RMS percent coefficients of variation across the population.ResultsApex and Delphi values were highly correlated (r ranged from 0.90 to 0.99). Excluding the right neck, the Apex precision error was found to be 20% to 25% lower than the Delphi (spine: 1.0% versus 1.2% (p < 0.05), total hip: 1.1% versus 1.3% (p < 0.05), right neck: 2.3% versus 2.6% (p > 0.1)). No statistically significant differences were found in the precision error of the Apex and Prodigy (p > 0.05) except for the right neck (2.3% versus 1.8% respectively, p = 0.03).ConclusionThe Apex software has significantly lower precision error compared to Delphi software with similar mean values, and similar precision to that of the Prodigy

One-loop approximation for the Heisenberg antiferromagnet

We use the diagram technique for spin operators to calculate Green's functions and observables of the spin-1/2 quantum Heisenberg antiferromagnet on a square lattice. The first corrections to the self-energy and interaction are taken into account in the chain diagrams. The approximation reproduces main results of Takahashi's modified spin-wave theory [Phys. Rev. B 40, 2494 (1989)] and is applicable in a wider temperature range. The energy per spin calculated in this approximation is in good agreement with the Monte Carlo and small-cluster exact-diagonalization calculations in the range 0 <= T < 1.2J where J is the exchange constant. For the static uniform susceptibility the agreement is good for T < 0.6J and becomes somewhat worse for higher temperatures. Nevertheless the approximation is able to reproduce the maximum in the temperature dependence of the susceptibility near T = 0.9J.Comment: 15 pages, 6 ps figure

An outbreak of food-poisoning due to a flour improver, potassium bromate

Click on the link to view