Superatom Representation of High-TC Superconductivity Revisited

A "super-atom" conceptual interface between chemistry and physics is proposed in order to assist in the search for higher TC superconductors. High-TC superconductivity HTSC is articulated as the entanglement of two disjoint electronic manifolds in the vicinity of a common Fermi energy. The resulting HTSC ground state couples near-degenerate protected local "super-atom" states to virtual magnons in an antiferromagnetic AFM embedding. The composite Cooper pairs emerge as the interaction particles for virtual magnons mediated "self-coherent entanglement" of super-atom states. A H\"uckel type resonating valence bond RVB formalism is employed in order to illustrate the real-space Cooper pairs as well as their delocalization and Bose Einstein condensation BEC on a ring of super-atoms. The chemical potential \mu(BEC) for Cooper pairs joining the condensate is formulated in terms of the super-exchange interaction, and consequently the TC in terms of the Ne\'el temperature. A rationale for the robustness of the HTSC ground state is proposed: achieving local maximum "electron correlation entropy" at the expense of non-local phase rigidity.Comment: 25 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:1007.411

A Tale of Two Entangled Instabilities: Dual Role of delta-O in HgBa2Ca(n-1)Cu(n)O(2(n+1)+delta)

Low-energy instabilities in the hole doped cuprates include, besides short range antiferromagnetic fluctuations and superconductivity, also ubiquitous translational and rotational symmetry breakings. The overwhelming majority of interpretations of these possibly related properties rely on mappings onto three bands spanned by the three atomic orbitals Cu3d(x2-y2)(sigma), O2px(sigma), and O2py(sigma), these three local orbitals spanning the Zhang-Rice band (ZRB), the lower Hubbard bands (LHB) and the upper Hubbard bands (UHB), respectively. Here we demonstrate by means of supercell Density Functional Theory (DFT) (a) how oxygen intercalation affects the structures of the buffer layers, and (b) how the attenuated crystal field pulls two additional oxygen bands in the CuO2 plane to the Fermi level. The self-consistent changes in electronic structure reflected in the corresponding changes in external potential comprise formal properties of the Hohenberg-Kohn theorems. Validation of present days' approximate exchange-correlation potentials to capture these qualitative effects by means of supercell DFT is made by comparing computed doping dependent structural shifts to corresponding experimentally observed correlations. The simplest generalization of Bardeen-Cooper-Schrieffer (BCS) theory is offered to articulate high critical temperature superconductivity (HTS) from a normal state where crystal field causes states related to two non-hybridizing bands to coalesce at EF.Comment: 18 pages, 1 table, 6 figure

Owning memories: a tale of two cities

In 1894 Queen Victoria opened the Salford Docks, now known as Salford Quays, home of MediaCityUK. At the time, Salford Docks were considered a masterpiece of engineering, allowing Manchester to circumvent the route through Liverpool and have access to international trade. The area was an ambitious hub for commerce, industrial activity and job prospects. Although more than 100 years have passed, Salford Quays is again under the spotlight and has the ambition to be a contemporary contender in the cultural industries market – this time focussing, through MediacityUK, on moving the media industry away from London. In order to attract such a prestigious focus, the developers have responded by building waterside apartments, luxury housing and speedy infrastructure and by promoting a successful professional lifestyle, with cultural and cutting-edge designer events. However, the local community seems to be more than ever alienated from this process, the sense of cultural collective memory being diluted. Throughout this paper, we are considering issues relating both to the historical significance of Salford Quays as well as to its cultural legacy within the local community. In order to do so, we are addressing the following research questions: How can the past be brought to into the present to support a sense of identity cohesion? Can Salford shake off the image of a derelict area and become the innovative creative quarter, through the (living) memories of its community? We will argue that the re- invention of Salford Quays as a new cutting-edge creative quarter happens at the expense of the historical memory of the place. In this way, local people and local memories do not become an integral part of the regeneration strategy, but are almost erased from the whole process

Another look at the inflation-productivity trade-off

Our aim in this paper is to test the robustness of the relation between total factor productivity growth and inflation to the specification of the model adopted for its identification. In doing so we estimate a generalized Box-Box cost function using data from the two-digit Standard Industrial Classification of manufacturing industries in Greece during the period 1964-1980. The results confirm that the acceleration of inflation from 1964-1972 to 1973-1980 reduced total factor productivity growth in a way that was both statistically significant and sizeable. In addition, they reveal that, even when the effect of inflation is separated from the effects of technical change and economies of scale, the choice of functional form is most crucial. The reason being that cost functions such as the translog, the generalized Leontief, and the generalized square root quadratic are not general enough to account for the sensitivity of estimates to model specification. On these grounds then we conclude that, for a precise estimation of the adverse impact of inflation on total factor productivity growth, it is imperative both to sort out the three effects involved and do so by adopting the most general flexible functional form available for the cost function.inflation, total factor productivity, generalized Box-Cox cost function, economic growth

The inflation-productivity trade-off revisited

Our aim in this paper is threefold. First, to test the robustness of the relation between total factor productivity growth and inflation to the specification of the estimating model; second, to test the stability of their relationship in the short run and in the long run, and third, to investigate the direction of causality between these two variables. To accomplish the first objective, we esti-mate a generalized Box-Box cost function using data from the two-digit Standard Industrial Clas- sification of manufacturing industries in Greece during the period 1964- 1980. The results show that: a) the acceleration of inflation from 1964- 1972 to 1973-1980 reduced total factor productiv-ity growth in a way that was both statistically significant and sizeable, and b) even when the ef-fect of inflation is separated from the effects of technical change and economies of scale, the choice of functional form is most crucial. With respect to the second objective, somewhat to our surprise, we find that the inflation-productivity trade-off prevails even in the long run. And, fi-nally, regarding the third objective, it emerges that in the great majority of two-digit manufactur-ing industries the causality runs from inflation to productivity. On these grounds we conclude that for a precise estimation of the relationship under consideration it is imperative to sort out the three effects involved, do so by adopting the most general flexible functional form for the cost function, and run the appropriate stability and causality tests.inflation; productivity; scale economies; technical change; generalized Box-Cox cost function; stability; causality

Particle-hole symmetry breaking in the pseudogap state of Pb0.55Bi1.5Sr1.6La0.4CuO6+d: A quantum-chemical perspective

Two Bi2201 model systems are employed to demonstrate how, beside the Cu-O \sigma-band, a second band of purely O2p\pi character can be made to cross the Fermi level owing to its sensitivity to the local crystal field. This result is employed to explain the particle-hole symmetry breaking across the pseudo-gap recently reported by Shen and co-workers, see M. Hashimoto et al., Nature Physics 6, (2010) 414. Support for a two-bands-on-a-checkerboard candidate mechanism for High-Tc superconductivity is claimed.Comment: 25 pages, 8 figure

Super-Atom Representation of High-TC Superconductivity

A resonating valence bond RVB approach is taken to demonstrate formation of real-space Cooper pairs and High-TC superconductivity HTS. Non-adiabatic coupling between holes aggregates (super-atoms) and undoped anti-ferromagnet cause virtual excitations in either system due to inter-system coupling. HTS is said to reflect cooperative co-existence of two Bose-Einstein condensates in terms of one real-space Cooper pair condensate, and a second magnon condensate, which form at the same critical temperature. TC is formulated in terms of the super-exchange interaction. Connection is made to an equivalent real-space BCS formulation of HTS. Novel perspectives on the HTS in the electron-doped Sr1-xLaxCuO2 and Nd2-xCexCuO4 emerge.Comment: 25 pages, 4 figure

The effects of reading and self-graphing on the reading fluency and comprehension of third grade students with special needs

The purpose of the study was to examine the effects of rereading and self-graphing on fluency and comprehension of third grade students with special needs. This study implemented a pretest-posttest design. The participants were six students with special needs from a third grade inclusion classroom reading at least two grade levels below third grade. Data was collected during a baseline phase, intervention phase, and postintervention phase. The independent variables were the use of rereading and selfgraphing of passages from the Critical Reading Inventory and The Jerry Johns Basic Reading Inventory. The dependent variable was the measure of the participants\u27 reading fluency and comprehension using the Critical Reading Inventory and The Jerry Johns Basic Reading Inventory. Overall, the results of the study demonstrated reading and selfgraphing to be an effective intervention to increase students\u27 fluency and comprehension. Participants in the study showed an increase in both fluency and comprehension by rereading and self-graphing results. Three participants had a greater increase in fluency, than in comprehension. Three of the participants had a greater increase in comprehension than in fluency. Results of this study show that rereading and self-monitoring of progress can be an effective strategy to improve the reading fluency and comprehension for students with special needs