Nanoscale electron-beam-driven metamaterial light sources

Free-standing and fiber-coupled photonic metamaterials act as nanoscale, free-electron-driven, tuneable light sources: emission occurs at wavelengths determined by structural geometry in response to electron-beam excitation of metamaterial resonant plasmonic modes

Fundamental Volatility is Regime Specific

A widely held notion holds that freely floating exchange rates are excessively volatile when judged against fundamentals and when moving from fixed to floating exchange rates. We re-examine the data and conclude that the disparity between the fundamentals and exchange rate volatility is more apparent than real, especially when the Deutsche Mark, rather than the dollar is chosen as the numeraire currency. We also argue, and indeed demonstrate, that in cross-regime comparisons one has to account for certain ‘missing variables’ which compensate for the fundamental variables’ volatility under fixed rates.

Umklapp scattering at reconstructed quantum-Hall edges

We study the low-lying excitations of a quantum-Hall sample that has undergone edge reconstruction such that there exist three branches of chiral edge excitations. Among the interaction processes that involve electrons close to the three Fermi points is a new type of Umklapp-scattering process which has not been discussed before. Using bosonization and a refermionization technique, we obtain exact results for electronic correlation functions and discuss the effect Umklapp scattering has on the Luttinger-liquid properties of quantum-Hall edges.Comment: 4 pages, 1 figure, uses elsart.cls and phbauth.cls (both are included), contribution to EP2DS-13, to be published in Physica

Uncertainties inherent in the decomposition of a Transformation

This contribution adds to the points on the <indeterminacy of special relativity> made by De Abreu and Guerra. We show that the Lorentz Transformation can be composed by the physical observations made in a frame K of events in a frame K-prime viz i) objects in K-prime are moving at a speed v relative to K, ii) distances and time intervals measured by K-prime are at variance with those measured by K and iii) the concept of simultaneity is different in K-prime compared to K. The order in which the composition is executed determines the nature of the middle aspect (ii). This essential uncertainty of the theory can be resolved only by a universal synchronicity as discussed in [1] based on the unique frame in which the one way speed of light is constant in all directions.Comment: 10 pages including an appendix. Published in the European Journal of Physics as a Comment. Eur. J. Phys. 29 (2008) L13-L1

Chiral boundary conditions for Quantum Hall systems

A quantum mesoscopic billiard can be viewed as a bounded electronic system due to some external confining potential. Since, in general, we do not have access to the exact expression of this potential, it is usually replaced by a set of boundary conditions. We discuss, in addition to the standard Dirichlet choice, the other possibilities of boundary conditions which might correspond to more complicated physical situations including the effects of many body interactions or of a strong magnetic field. The latter case is examined more in details using a new kind of chiral boundary conditions for which it is shown that in the Quantum Hall regime, bulk and edge characteristics can be described in a unified way.Comment: 16 pages, LaTeX, 2 figures, to be published in the Proceedings of the Minerva workshop on Mesoscopics, Fractals and Neural Networks, Phil. Mag. (1997

Non-Keplerian orbits using low thrust, high ISP propulsion systems

The technology of high ISP propulsion systems with long lifetime and low thrust is improving, and opens up numerous possibilities for future missions. The use of continuous thrust can be applied in all directions including prependicular to the flight direction to force the spacecraft out of a natural orbit (or A orbit) into a displaced orbit (a non-Keplerian or B orbit): such orbits could have a diverse range of potential applications. Using the equations of motion we generate a catalogue of these B orbits corresponding to displaced orbits about the Sun, Mercury, Venus, Earth, the Moon, Mars, Phobos and Deimos, the dwarf planet Ceres, and Saturn. For each system and a given thrust, contours both in and perpendicular to the plane of the ecliptic are produced in the rotating frame, in addition to an equithrust surface. Together these illustrate the possible domain of B orbits for low thrust values between 0 and 300mN. Further, the required thrust vector orientation for the B orbit is obtained and illustrated. The sub-category of solar sail enabled missions is also considered. Such a catalogue of B orbits enables an efficient method of indentifying regions of possible displaced orbits for potential use in future missions

Nurses’ Perceptions of Community Health Workers in Health Care

The purpose of this study was to explore registered nurses’ and social workers’ experiences working with community health workers (CHWs) in clinics and homecare. Six nurses participated in individual, semi-structured interviews. Analysis of interview transcripts revealed that CHWs are considered vital members of the health care team. Their expert knowledge of community resources and ability to bridge cultural and language gaps make them ideally placed to impact social determinants of health. The role of the CHW is evolving. Team building and role clarity are essential elements for successful integration of CHWs on health care teams. The investigator was unable to recruit social workers for this study. Further research is needed to solicit social workers’ perceptions of the CHW role in health and human services

Exploring Social Media for Event Attendance

Large popular events are nowadays well reflected in social media fora (e.g. Twitter), where people discuss their interest in participating in the events. In this paper we propose to exploit the content of non-geotagged posts in social media to build machine-learned classifiers able to infer users' attendance of large events in three temporal periods: before, during and after an event. The categories of features used to train the classifier reflect four different dimensions of social media: textual, temporal, social, and multimedia content. We detail the approach followed to design the feature space and report on experiments conducted on two large music festivals in the UK, namely the VFestival and Creamfields events. Our attendance classifier attains very high accuracy with the highest result observed for the Creamfields dataset ~87% accuracy to classify users that will participate in the event

Registered Nurses’ Perceptions of Community Health Workers

Objective: The objective was to explore the experiences of Registered Nurses and Licensed Social Workers who work directly with Community Health Workers (CHWs) in health care. Design and Sample: A descriptive qualitative design was utilized. Six registered nurses participated in semi-structured interviews. Interviews were audiotaped. Content analysis consisted of identifying themes and patterns that emerged from the narratives. Results: Three themes were identified, 1) the importance of role clarity, 2) relationship building, and 3) filling in gaps in care. Conclusions: Nurses consider CHWs to be vital members of the health car team. CHWs’ extensive knowledge of community resources and their ability to provide culturally sensitive care has benefits for both patients and health professionals. The role of the CHW is evolving. Clear delineation roles is an important factor in the implementation of new health professions