Signifying quantum benchmarks for qubit teleportation and secure communication using Einstein-Podolsky-Rosen steering inequalities

The demonstration of quantum teleportation of a photonic qubit from Alice to Bob usually relies on data conditioned on detection at Bob's location. I show that Bohm's Einstein-Podolsky-Rosen (EPR) paradox can be used to verify that the quantum benchmark for qubit teleportation has been reached, without postselection. This is possible for scenarios insensitive to losses at the generation station, and with efficiencies of $\eta_{B}>1/3$ for the teleportation process. The benchmark is obtained, if it is shown that Bob can {}"steer" Alice's record of the qubit as stored by Charlie. EPR steering inequalities involving $m$ measurement settings can also be used to confirm quantum teleportation, for efficiencies $\eta_{B}>1/m$, if one assumes trusted detectors for Charlie and Alice. Using proofs of monogamy, I show that two-setting EPR steering inequalities can signify secure teleportation of the qubit state.Comment: 10 pages, 1 Figur

Micro-Arcsecond Radio Astrometry

Astrometry provides the foundation for astrophysics. Accurate positions are required for the association of sources detected at different times or wavelengths, and distances are essential to estimate the size, luminosity, mass, and ages of most objects. Very Long Baseline Interferometry at radio wavelengths, with diffraction-limited imaging at sub-milliarcsec resolution, has long held the promise of micro-arcsecond astrometry. However, only in the past decade has this been routinely achieved. Currently, parallaxes for sources across the Milky Way are being measured with ~10 uas accuracy and proper motions of galaxies are being determined with accuracies of ~1 uas/y. The astrophysical applications of these measurements cover many fields, including star formation, evolved stars, stellar and super-massive black holes, Galactic structure, the history and fate of the Local Group, the Hubble constant, and tests of general relativity. This review summarizes the methods used and the astrophysical applications of micro-arcsecond radio astrometry.Comment: To appear in Annual Reviews of Astronomy and Astrophysics (2014

The assessment and management of pain in older people : a systematic review of the literature

This paper presents the findings of a systematic literature which was carried out to determine the most appropriate strategies that could be carried out for the assessment and management of pain in residents living in care homes. Five hundred and seventy-one papers were initially identified and from this total 70 papers were found to be appropriate. These papers were organised into five key themes; Assessment & Behavioural Assessment, Barriers/Attitudes/Perceptions, Cognitive Behavioural Therapy, Complementary Therapies and Education/Guidelines. Most of the papers related to pain in this group were pharmacological suggesting that health care professionals generally feel that pharmacological approaches are the only way to manage pain in this group. Nevertheless, the non-pharmacological papers do suggest that there are other methods of pain control which should be considered. Recommendations for further research are made.Burdett Trust for Nursin

A Trigonometric Parallax of Sgr B2

We have measured the positions of water masers in Sgr B2, a massive star forming region in the Galactic center, relative to an extragalactic radio source with the Very Long Baseline Array. The positions measured at 12 epochs over a time span of one year yield the trigonometric parallax of Sgr B2 and hence a distance to the Galactic center of Ro=7.9 (+0.8/-0.7) kpc. The proper motion of Sgr B2 relative to Sgr A* suggests that Sgr B2 is about 0.13 kpc nearer than the Galactic center, assuming a low-eccentricity Galactic orbit.Comment: Submitted to ApJ; 4 tables; 3 figures. Version 2 corrects Fig. 2 which was missing some dat

The Eurovision St Andrews collection of photographs

This report describes the Eurovision image collection compiled for the ImageCLEF (Cross Language Evaluation Forum) evaluation exercise. The image collection consists of around 30,000 photographs from the collection provided by the University of St Andrews Library. The construction and composition of this unique image collection are described, together with the necessary information to obtain and use the image collection

Evolution of female multiple mating : A quantitative model of the “sexually selected sperm” hypothesis

This article is protected by copyright. All rights reserved. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Peer reviewedPublisher PD