Electron dynamics in the normal state of cuprates: spectral function, Fermi surface and ARPES data

An influence of the electron-phonon interaction on excitation spectrum and damping in a narrow band electron subsystem of cuprates has been investigated. Within the framework of the t-J model an approach to solving a problem of account of both strong electron correlations and local electron-phonon binding with characteristic Einstein mode $\omega _0$ in the normal state has been presented. In approximation Hubbard-I it was found an exact solution to the polaron bands. We established that in the low-dimensional system with a pure kinematic part of Hamiltonian a complicated excitation spectrum is realized. It is determined mainly by peculiarities of the lattice Green's function. In the definite area of the electron concentration and hopping integrals a correlation gap may be possible on the Fermi level. Also, in specific cases it is observed a doping evolution of the Fermi surface. We found that the strong electron-phonon binding enforces a degree of coherence of electron-polaron excitations near the Fermi level and spectrum along the nodal direction depends on wave vector module weakly. It corresponds to ARPES data. A possible origin of the experimentally observed kink in the nodal direction of cuprates is explained by fine structure of the polaron band to be formed near the mode -$\omega _0$

Tool provides constant purge during tube welding

Tool provides a constant purge of inert gas during in-place welding of tubular components to prevent contamination and oxidation. It also permits self-jiggings of the tube and sleeve to be welded

Hormone-treated beef: Should Britain accept it after Brexit?

This Briefing explains why the use of synthetic, industrially-manufactured hormones in beef production, and the threat of importing hormone-produced beef after Brexit, matter for UK consumers. There is robust scientific evidence showing that meat produced using one key hormone (17β-oestradiol) increases the cancer risk to consumers, while for the rest the available evidence is insufficient to show that their use is acceptably safe. The Briefing outlines the basis of the scientific and policy disputes over the use of supplementary hormones in beef cattle production. It shows that, although the USA is most associated with hormone-reared beef, other countries that want to export their beef to the UK, post Brexit, either allow hormones to be used, or are suspected of doing so. The EU has been reasonably vigilant on consumers’ behalf on this issue, and it has robust scientific grounds for its ban on their use. The risk from beef hormones is one of many issues on which UK consumers have benefited from the EU’s measures to protect public and environmental health. Chlorine-washed chicken is another example

Weakening UK food law enforcement: a risky tactic in Brexit

The UK Food Standards Agency (FSA) is beginning to roll out a far-reaching programme of regulatory change called Regulating Our Future (ROF). This Briefing Paper argues that ROF risks: - Making the UK’s food supply less safe by further weakening systems that are already too weak; - Undermining the ability of UK food producers to export to the EU after Brexit; - Creating irreconcilable conflicts of interests, because rather than having public officials inspect food businesses, the food businesses will be able to choose who ‘marks their homework’. Professors Erik Millstone (University of Sussex) and Tim Lang (City, University of London) provide a detailed and powerful critique of the Food Standards Agency’s proposals. They conclude that ROF represents a fundamental and detrimental shift in the role, approach and public responsibilities of the FSA and the local authority officers who are the bedrock of food safety in the UK. They also show why these unwelcome proposals are especially unwise in the context of negotiations over Brexit, when the public needs a strong, vigilant and effective FSA. The authors call for ROF to be halted pending further review by a special Parliamentary Joint Select Committee of the Health and Environment, Food & Rural Affairs Committees

Summary of the functions and capabilities of the structural analysis and matrix interpretive system computer program

Functions and capabilities of large capacity structural analysis and matrix interpretive system digital computer program to analyze frame and shell structure

Summary of the functions and capabilities of the structural analysis system computer program

Functions and operations of structural analysis system computer progra

Beyond Megalopolis: Exploring America’s New “Megapolitan” Geography

The Metropolitan Institute at Virginia Tech identifies ten US “Megapolitan Areas”— clustered networks of metropolitan areas that exceed 10 million total residents (or will pass that mark by 2040) . Six Megapolitan Areas lie in the eastern half of the United States, while four more are found in the West. Megapolitan Areas extend into 35 states, including every state east of the Mississippi River except Vermont. Sixty percent of the Census Bureau’s “Consolidated Statistical Areas” are found in Megapolitan Areas, as are 39 of the nation’s 50 most populous metropolitan areas. As of 2003, Megapolitan Areas contained less than a fifth of all land area in the lower 48 states, but captured more than two-thirds of total US population with almost 200 million people. Megapolitan Areas are expected to add 83 million people (or the current population of Germany) by 2040, accounting for seven in every ten new Americans. By 2040, a projected 33 trillion dollars will be spent on Megapolitan building construction. The figure represents over three quarters of all the capital that will be expended nationally on private real estate development. In 2004, Democratic candidate John Kerry won the Megapolitan Area popular vote by 51.6 percent to 48.4 for President George W. Bush—or almost the exact reverse of the nation as a whole. Kerry received 46.4 million Megapolitan votes, while Bush won 43.5 million. Megapolitan geography reframes many planning and public policy debates, touching on such issues as environmental impact, transportation, and urban sprawl

Electron transfer in the nonadiabatic regime: Crossover from quantum-mechanical to classical behaviour

We study nonadiabatic electron transfer within the biased spin-boson model. We calculate the incoherent transfer rate in analytic form at all temperatures for a power law form of the spectral density of the solvent coupling. In the Ohmic case, we present the exact low temperature corrections to the zero temperature rate for arbitrarily large bias energies between the two redox sites. Both for Ohmic and non-Ohmic coupling, we give the rate in the entire regime extending from zero temperature, where the rate depends significantly on the detailed spectral behaviour, via the crossover region, up to the classical regime. For low temperatures, the rate shows characteristic quantum features, in particular the shift of the rate maximum to a bias value below the reorganization energy, and the asymmetry of the rate around the maximum. We study in detail the gradual extinction of the quantum features as temperature is increased.Comment: 17 pages, 4 figures, to be published in Chem. Phy