Conductance fluctuations and boundary conditions

The conductance fluctuations for various types for two-- and three--dimensional disordered systems with hard wall and periodic boundary conditions are studied, all the way from the ballistic (metallic) regime to the localized regime. It is shown that the universal conductance fluctuations (UCF) depend on the boundary conditions. The same holds for the metal to insulator transition. The conditions for observing the UCF are also given.Comment: 4 pages RevTeX, 5 figures include

Prestige drives epistemic inequality in the diffusion of scientific ideas

The spread of ideas in the scientific community is often viewed as a competition, in which good ideas spread further because of greater intrinsic fitness, and publication venue and citation counts correlate with importance and impact. However, relatively little is known about how structural factors influence the spread of ideas, and specifically how where an idea originates might influence how it spreads. Here, we investigate the role of faculty hiring networks, which embody the set of researcher transitions from doctoral to faculty institutions, in shaping the spread of ideas in computer science, and the importance of where in the network an idea originates. We consider comprehensive data on the hiring events of 5032 faculty at all 205 Ph.D.-granting departments of computer science in the U.S. and Canada, and on the timing and titles of 200,476 associated publications. Analyzing five popular research topics, we show empirically that faculty hiring can and does facilitate the spread of ideas in science. Having established such a mechanism, we then analyze its potential consequences using epidemic models to simulate the generic spread of research ideas and quantify the impact of where an idea originates on its longterm diffusion across the network. We find that research from prestigious institutions spreads more quickly and completely than work of similar quality originating from less prestigious institutions. Our analyses establish the theoretical trade-offs between university prestige and the quality of ideas necessary for efficient circulation. Our results establish faculty hiring as an underlying mechanism that drives the persistent epistemic advantage observed for elite institutions, and provide a theoretical lower bound for the impact of structural inequality in shaping the spread of ideas in science.Comment: 10 pages, 8 figures, 1 tabl

Electric coupling to the magnetic resonance of split ring resonators

We study both theoretically and experimentally the transmission properties of a lattice of split ring resonators (SRRs) for different electromagnetic (EM) field polarizations and propagation directions. We find unexpectedly that the incident electric field E couples to the magnetic resonance of the SRR when the EM waves propagate perpendicular to the SRR plane and the incident E is parallel to the gap-bearing sides of the SRR. This is manifested by a dip in the transmission spectrum. A simple analytic model is introduced to explain this interesting behavior.Comment: 4 pages, 4 figure

Low Loss Metamaterials Based on Classical Electromagnetically Induced Transparency

We demonstrate theoretically that electromagnetically induced transparency can be achieved in metamaterials, in which electromagnetic radiation is interacting resonantly with mesoscopic oscillators rather than with atoms. We describe novel metamaterial designs that can support full dark resonant state upon interaction with an electromagnetic beam and we present results of its frequency-dependent effective permeability and permittivity. These results, showing a transparency window with extremely low absorption and strong dispersion, are confirmed by accurate simulations of the electromagnetic field propagation in the metamaterial

Mirages and enhanced magnetic interactions in quantum corrals

We develop a theory for the interactions between magnetic impurities in nanoscopic systems. The case of impurities in quantum corrals built on the (111) Cu surface is analyzed in detail. For elliptical corrals with one impurity, clear magnetic mirages are obtained. This leads to an enhancement of the inter-impurity interactions when two impurities are placed at special points in the corral. We discuss the enhancement of the conduction electron response to the local perturbation in other nanoscopic systems.Comment: 7 pages, 5 figure

Quantifying how user-interaction can modify the perception of the value of climate information: A Bayesian approach

ArticleThis is the final version of the article. Available from Elsevier via the DOI in this record.The growing attention user relevance is receiving in the context of climate services is giving new light to engagement activities. However, while there is an almost unanimous consensus that these are important to the delivery of usable services, there is relatively little quantitative evidence of their impact on the usefulness of the service or its value as perceived by the users and decision-makers. Using a simple Bayesian decision theoretic framework, we have analysed how the perceived value of the service changes as a function of the user’s belief in the accuracy of the forecast. Based on this, we conclude, that, at least for the generic users adopted for our analysis, 30 or more repeated forecasts may be needed to ascertain the real user value of a predictive service. However, we argue that engagement between users and service providers can play a significant role in modifying the perceived accuracy and value of the service, bringing it closer in line with the objective evaluation. This requires feedback from users on both the specific climate information content and its presentation, alongside exploring the user’s attitude to risk. If appropriate engagement can be achieved, this work suggests that it has the potential to alter the overall perceived cost-benefit ratio over a relatively short period of time, enabling users to make best use of the available climate information.This work was supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). The authors wish to acknowledge all of those who contributed indirectly to the development of the EUPORIAS winter transport prototype (Seasonal Prototype: Risk of Impacts from NAO on Transport; http://sprint.euporias.eu/), through scientific discussion, review, data provision, stakeholder engagement and facilitation: Erika Palin, Adam Scaife, Anca Brookshaw, Alberto Arribas, and the UK Department for Transport-led stakeholder group. The UK Government Department for Transport is acknowledged for providing financial support, in parallel to that received from EUPORIAS, for the SPRINT prototype. EUPORIAS was funded by the European Commission through the 7th Framework Programme for Research, grant agreement 308291