The influence of candidates' physical attributes on patient ratings in simulated assessments of clinical practice.

BACKGROUND: We have previously shown that clinical examiners' scoring is not negatively impacted when a candidate has a tattoo, unnatural hair colour, or a regional accent. We investigated whether these physical attributes in exam candidates impact patient scoring. METHODS: Simulated/real patients were randomly assigned to watch five videos of simulated candidate performances of a cranial nerve examination: clear fail, borderline, good, 'clear pass' without an attribute, and 'clear pass' with one of the attributes (tattoo, purple hair, accent). Participants scored domains of communication and professionalism. We compared scores for the clear pass candidates with and without attributes. RESULTS: One hundred and eighty three patients participated. The total scores for the candidates with tattoos and purple hair were higher than the candidate with no physical attribute (p < 0.001). For the candidate with a Liverpool English accent no difference was identified (p = 0.120). CONCLUSIONS: The presence of certain physical attributes (tattoos or purple hair) was associated with higher scores given by patients to candidates in a simulated physical examination station.

The influence of candidates' physical attributes on assessors' ratings in clinical practice.

BACKGROUND: Assessments of physician competence in the work-place are common and often contribute to high-stakes assessments. Previous research suggests that assessors' judgements can be influenced by candidates' physical attributes. We investigated whether simulated candidates' scores were influenced by assessor bias based on tattoos, hair colour, and a regional accent. METHODS: We used an experimental, video-based, single-blinded, randomised, internet-based design. We created videos of simulated medical intern performances of a clinical examination at four different standards of competence. Four videos were also created of simulated candidates performing at a 'clear pass' standard, with either no stereotypical attribute (CPX), purple hair (CPH), tattoos (CPT) or a Liverpool English accent (CPA). Assessors were randomly assigned to watch five videos including the "clear pass" candidate without an attribute and one of the "clear pass" candidates with an attribute and asked to give an overall global grade for each candidate. We compared the global grades for the clear pass candidates with and without attributes. RESULTS: Ninety-eight assessors were included in the analysis. The total scores for the candidates with stereotyped attributes were not significantly lower than the candidate with no attribute. Assessors showed moderate levels of agreement between the global grades awarded for all the candidates. The global grades awarded to candidate with a stereotypical attribute were not significantly lower than for those without. CONCLUSIONS: The presence of tattoos, purple hair, or a regional accent did not systematically negatively influence the grade or score awarded by assessors to candidates in observed clinical examination scenarios.

Quantifying the Mesoscopic Nature of Einstein-Podolsky-Rosen Nonlocality.

Evidence for Bell's nonlocality is so far mainly restricted to microscopic systems, where the elements of reality that are negated predetermine results of measurements to within one spin unit. Any observed nonlocal effect (or lack of classical predetermination) is then limited to no more than the difference of a single photon or electron being detected or not (at a given detector). In this paper, we analyze experiments that report the Einstein-Podolsky-Rosen (EPR) steering form of nonlocality for mesoscopic photonic or Bose-Einstein condensate systems. Using an EPR steering parameter, we show how the EPR nonlocalities involved can be quantified for four-mode states, to give evidence of EPR-nonlocal effects corresponding to a two-mode number difference of 10^{5} photons, or of several tens of atoms (at a given site). Applying to experiments, we also show how the variance criterion of Duan, Giedke, Cirac and Zoller for EPR entanglement can be used to determine a lower bound on the number of particles in a pure two-mode EPR-entangled or steerable state.

Pulsed Entanglement of Two Optomechanical Oscillators and Furry's Hypothesis.

A strategy for generating entanglement between two separated optomechanical oscillators is analyzed, using entangled radiation produced from down-conversion and stored in an initiating cavity. We show that the use of pulsed entanglement with optimally shaped temporal modes can efficiently transfer quantum entanglement into a mechanical mode, then remove it after a fixed waiting time for measurement. This protocol could provide new avenues for testing for bounds on decoherence in massive systems that are spatially separated, as originally suggested by Furry not long after the discussion by Einstein-Podolsky-Rosen and Schrödinger of entanglement.

Nonlinear entanglement and its application to generating cat States.

The Einstein-Podolsky-Rosen (EPR) paradox, which was formulated to argue for the incompleteness of quantum mechanics, has since metamorphosed into a resource for quantum information. The EPR entanglement describes the strength of linear correlations between two objects in terms of a pair of conjugate observables in relation to the Heisenberg uncertainty limit. We propose that entanglement can be extended to include nonlinear correlations. We examine two driven harmonic oscillators that are coupled via third-order nonlinearity can exhibit quadraticlike nonlinear entanglement which, after a projective measurement on one of the oscillators, collapses the other into a cat state of tunable size.

Classifying directional Gaussian entanglement, Einstein-Podolsky-Rosen steering, and discord.

Using Venn diagrams, we classify the different types of two-mode Gaussian continuous variable quantum correlation including directional entanglement and Einstein-Podolsky-Rosen (EPR) steering. We establish unified signatures for one- and two-way quantum steering, entanglement, and discord beyond entanglement in terms of an EPR-type variance. By focusing on Gaussian states, we link an optimized condition for entanglement based on an EPR variance to the Simon-Peres condition. This allows us to quantify the asymmetry of the Gaussian entanglement, and to relate the asymmetry to a directional quantum teleportation protocol where Alice and Bob possess asymmetrically noisy channels. Our analysis enables a determination of the type and direction of quantum correlation in a way that is easily measured in experiment. We also find that for symmetric states, when discord exceeds a certain threshold, the states are necessarily steerable.

Genuine multipartite Einstein-Podolsky-Rosen steering.

We develop the concept of genuine N-partite Einstein-Podolsky-Rosen (EPR) steering. This nonlocality is the natural multipartite extension of the original EPR paradox. Useful properties emerge that are not guaranteed for genuine multipartite entangled states. In particular, there is a close link with the task of one-sided, device-independent quantum secret sharing. We derive inequalities to demonstrate multipartite EPR steering for Greenberger-Horne-Zeilinger and Gaussian continuous variable states in loophole-free scenarios.

Einstein-Podolsky-Rosen entanglement strategies in two-well Bose-Einstein condensates.

Criteria suitable for measuring entanglement between two different potential wells in a Bose-Einstein condensation are evaluated. We show how to generate the required entanglement, utilizing either an adiabatic two-mode or a dynamic four-mode interaction strategy, with techniques that take advantage of s-wave scattering interactions to provide the nonlinear coupling. The dynamic entanglement method results in an entanglement signature with spatially separated detectors, as in the Einstein-Podolsky-Rosen paradox.

Testing for multipartite quantum nonlocality using functional bell inequalities.

We show that arbitrary functions of continuous variables, e.g., position and momentum, can be used to generate tests that distinguish quantum theory from local hidden variable theories. By optimizing these functions, we obtain more robust violations of local causality than obtained previously. We analytically calculate the optimal function and include the effect of nonideal detectors and noise, revealing that optimized functional inequalities are resistant to standard forms of decoherence. These inequalities could allow a loophole-free Bell test with efficient homodyne detection.

Digital quantum memories with symmetric pulses.

We propose a digital approach to quantum memories using a single-mode oscillator-cavity model, in which the coupling is shaped in time to provide the optimum interface to a time-symmetric input pulse. Our generic model is applicable to any linear storage medium ranging from a superconducting device to an atomic medium.

Spin entanglement, decoherence and Bohm's EPR paradox.

We obtain criteria for entanglement and the EPR paradox for spin-entangled particles and analyse the effects of decoherence caused by absorption and state purity errors. For a two qubit photonic state, entanglement can occur for all transmission efficiencies. In this case, the state preparation purity must be above a threshold value. However, Bohm's spin EPR paradox can be achieved only above a critical level of loss. We calculate a required efficiency of 58%, which appears achievable with current quantum optical technologies. For a macroscopic number of particles prepared in a correlated state, spin entanglement and the EPR paradox can be demonstrated using our criteria for efficiencies eta > 1/3 and eta > 2/3 respectively. This indicates a surprising insensitivity to loss decoherence, in a macroscopic system of ultra-cold atoms or photons.

Bell inequalities for continuous-variable correlations.

We derive a new class of correlation Bell-type inequalities. The inequalities are valid for any number of outcomes of two observables per each of n parties, including continuous and unbounded observables. We show that there are no first-moment correlation Bell inequalities for that scenario, but such inequalities can be found if one considers at least second moments. The derivation stems from a simple variance inequality by setting local commutators to zero. We show that above a constant detector efficiency threshold, the continuous-variable Bell violation can survive even in the macroscopic limit of large n. This method can be used to derive other well-known Bell inequalities, shedding new light on the importance of non-commutativity for violations of local realism.

Signatures for generalized macroscopic superpositions.

We develop criteria sufficient to enable detection of macroscopic coherence where there are not just two macroscopically distinct outcomes for a pointer measurement, but rather a spread of outcomes over a macroscopic range. The criteria provide a means to distinguish a macroscopic quantum description from a microscopic one based on mixtures of microscopic superpositions of pointer-measurement eigenstates. The criteria are applied to Gaussian-squeezed and spin-entangled states.

A non-radioactive method for measuring Cu uptake in HepG2 cells.

At present, all data on Cu uptake and metabolism have been derived from radioactive uptake experiments. These experiments are limited by the availability of the radioactive isotopes 64Cu or 67Cu, and their short half-life (12.5 and 62 h, respectively). In this paper, we investigate an alternative method to study the uptake of Cu with natural isotopes in HepG2 cells, a liver cell line used extensively to study Cu metabolism. In nature, Cu occurs as two stable isotopes, 63Cu and 65Cu (63Cu/65Cu = 2.23). This ratio can be measured accurately using inductively coupled plasma mass spectrometry (ICP-MS). In initial experiments, we attempted to measure the time course of Cu uptake using 65Cu. The change in the 63Cu/65Cu ratio, however, was too small to allow measurement of Cu uptake by the cells. To overcome this difficulty, the natural 63Cu/65Cu ratio in HepG2 cells was altered using long-term incubation with 63Cu. This had a significant effect on Cu concentration in HepG2 cells, changing it from 81.9 +/- 9.46 pmol microg DNA(-1) (week 1) to 155 +/- 8.63 pmol microg DNA(-1) (week 2) and stabilising at 171 +/- 4.82 pmol microg DNA(-1) (week 3). After three weeks of culture with 2 microM 63Cu the 63Cu/65Cu changed from 2.18 +/- 0.05 to 15.3 +/- 1.01. Cu uptake was then investigated as before using 65Cu. Uptake was linear over 60 min, temperature dependent and consistent with previous kinetics data. These observations suggest that stable isotope ICP-MS provides an alternative technique for the study of Cu uptake by HepG2 cells.

Copper absorption from foods labelled intrinsically and extrinsically with Cu-65 stable isotope.

OBJECTIVE: To determine copper absorption from copper containing foods labelled either intrinsically or extrinsically with a highly enriched Cu-65 stable isotope label. DESIGN: A longitudinal cross-over study. SETTING: The study was conducted at the Institute of Food Research, Human Nutrition Unit, Norwich, UK. SUBJECTS: Subjects were recruited locally via advertisements placed around the Norwich Research Park. A total of 10 volunteers (nine female, one male) took part in the study, but not all volunteers completed each of the test meals. INTERVENTIONS: A highly enriched Cu-65 stable isotope label was administered to volunteers in the form of a reference dose or in breakfast test meals consisting of red wine, soya beans, mushrooms or sunflower seeds. Faecal monitoring and mass spectrometry techniques were used to estimate the relative quantities of copper absorbed from the different test meals. RESULTS: True copper absorption from the reference dose (54%) was similar to extrinsically labelled red wine (49%) and intrinsically labelled sunflower seeds (52%), but significantly higher than extrinsically labelled mushrooms (35%), intrinsically (29%) and extrinsically (15%) labelled soya beans and extrinsically labelled sunflower seed (32%) test meals. CONCLUSIONS: The use of Cu-65 extrinsic labels in copper absorption studies requires validation according to the food being examined; intrinsic and extrinsic labelling produced significantly different results for sunflower seeds.

Selective extraction of blood plasma exchangeable copper for isotope studies of dietary copper absorption.

Measuring mineral absorption by fecal monitoring is labor-intensive and relies on good volunteer compliance. Blood indicators of absorption could be advantageous and we have developed a method for selective extraction-of recently absorbed (exchangeable) copper based on dialysis of plasma with histidine and subsequent copper extraction using Chelex resin. The potential for measuring copper absorption by transient enrichment of exchangeable copper with the stable isotope 65Cu from an ingested tracer, was also investigated. This method was compared with that of the fecal monitoring technique in a human volunteer, who consumed a 6 mg dose of 65Cu with inhibitors of copper absorption. Holmium was used as a non-absorbable rare-earth marker of unabsorbed tracer excretion, allowing estimation of re-secreted 65Cu (44 microg d(-1)), and hence calculation of true tracer absorption, which was only 10.8%. Monitoring plasma tracer kinetics showed potential for estimation of copper absorption without the need for fecal copper analysis.

A high oat-bran intake does not impair zinc absorption in humans when added to a low-fiber animal protein-based diet.

Oat bran has a high phytate content and a low or inactivated phytase activity. A high intake of oat bran could therefore result in an impaired absorption of trace elements. The effect of a mean daily intake of 142 g of oat bran (102 g/10 MJ) on absorption of zinc was evaluated by the use of stable isotopes and fecal monitoring in 12 healthy subjects (6 males and 6 females). Each subject participated in two separate diet periods each of 21 d with identical low-fiber diets and with oat bran added in one of the periods. The oat bran was incorporated into bread and served at three daily main meals. The intake of zinc and phytate per 10 MJ was 138 micromol (9.0 mg) and 0.5 mmol, respectively, in the low-fiber period and 225 micromol (14.7 mg) and 4.0 mmol, respectively, in the oat bran period. Stable isotopes of zinc ((70)Zn) were added to the diets at d 7 of each period. The fractional absorptions (means +/- SD) of zinc from the low-fiber and oat bran diets were 0.48 +/- 0.11 and 0.40 +/- 0.15 (P = 0.07), respectively. The higher zinc content in the oat bran period resulted in a greater amount of zinc absorbed (64 +/- 19 micromol and 99 +/- 51 micromol, respectively, P = 0.009). Balance data suggest that the higher absorbed amount of zinc resulted in correspondingly higher intestinal endogenous excretion of zinc. In conclusion, the absorption of zinc was high and not affected by addition of oat bran.

Molybdenum-induced changes in the epiphyseal growth plate.

Molybdenum (Mo), at high concentrations, induces changes in the epiphyseal growth plate through its effects on copper (Cu) metabolism but it is unclear whether or not Mo can induce changes independent of its effects on copper status. To this end, the effect of Mo on longitudinal bone growth was examined in rats. Dietary Mo was given either as ammonium heptamolybdate or as ammonium tetrathiomolybdate, the latter producing a marked Cu deficiency. There was a significant reduction in longitudinal bone growth in both groups; however, growth plate width was increased only in the Cu-deficient animals due to an increase in the width of the zone of transitional/hypertrophic chondrocytes. Both glucose 6-phosphate dehydrogenase activity and cell proliferation (assessed by bromodeoxyuridine incorporation) were markedly decreased in the proliferating zone of the growth plate in both Mo-treated groups. These changes were not apparently related to changes in circulating vitamin D metabolites or insulin-like growth factor-1. The results indicate that excess Mo impairs cell proliferation within the growth plate, whereas the effects of copper deficiency are more related to chondrocyte differentiation. Thus, Mo can induce changes in longitudinal bone growth which are distinct from those resulting from Cu deficiency.