Continuous-variable Einstein-Podolsky-Rosen paradox with traveling-wave second-harmonic generation

The Einstein-Podolsky-Rosen paradox and quantum entanglement are at the heart of quantum mechanics. Here we show that single-pass traveling-wave second-harmonic generation can be used to demonstrate both entanglement and the paradox with continuous variables that are analogous to the position and momentum of the original proposal.

Multipartite entanglement and quantum state exchange

We investigate multipartite entanglement in relation to the process of quantum state exchange. In particular, we consider such entanglement for a certain pure state involving two groups of N trapped atoms. The state, which can be produced via quantum state exchange, is analogous to the steady-state intracavity state of the subthreshold optical nondegenerate parametric amplifier. We show that, first, it possesses some 2N-way entanglement. Second, we place a lower bound on the amount of such entanglement in the state using a measure called the entanglement of minimum bipartite entropy.

Carotid intima-media thickness, cardiovascular risk factors and albuminuria in a remote Australian Aboriginal community

Background: Rates of cardiovascular disease and renal disease in Australian Aboriginal communities are high, as is the prevalence of some 'traditional' cardiovascular (CV) risk factors, such as diabetes and cigarette smoking. Recent work has highlighted the importance of markers of inflammation, such as C-reactive protein (CRP), homocysteine and albuminuria as predictors of cardiovascular risk in urban westernised settings. It is not clear how these factors relate to outcome in the setting of these remote communities, but very high CRP concentrations have been shown in this and other Aboriginal communities. Methods and results: In a cross-sectional survey including 237 adults in a remote Aboriginal community in the Northern Territory of Australia, we measured carotid intima-media thickness (IMT), together with blood pressure, diabetes, lipid levels, smoking and albuminuria, CRP and fibrinogen, serum homocysteine concentration, and IgG titres for Chlamydia pneumoniae, Helicobacter pylori and cytomegalovirus. Median carotid IMT was 0.63 [interquartile range 0.54-0.71] mm. As a categorical outcome, the prevalence of the highest IMT quartile ('increased IMT', greater than or equal to0.72 mm) was compared with the lower three quartiles. Increased IMT was associated in univariate analyses with greater waist circumference, systolic BP, fibrinogen and serum albumin concentrations, urine albumin/creatinine ratio and older age as continuous variables. Associations of increased IMT with some continuous variables were not linear; univariate associations were seen with the highest quartile (versus all other quartiles) of CRP and homocysteine concentration and CMV IgG titre. In a multivariate model age, smoking, waist circumference and the highest quartile of CRP concentrations (greater than or equal to14 mg/l) remained significant predictors of IMT greater than or equal to0.72 mm. Conclusions: Measurement of carotid IMT was possible in this remote setting. Increased IMT (greater than or equal to0.72 mm) was associated with increased CRP concentrations over a range that suggests infection/inflammation may be important determinants of cardiovascular risk in this setting. The associations of IMT with markers of renal disease seen in univariate analyses were explained in this analysis by confounding due to the associations of urine ACR with other risk factors. (C) 2004 Published by Elsevier Ireland Ltd.

Bitwise bell-inequality violations for an entangled state involving 2N ions

Following on from previous work [J.-A. Larsson, Phys. Rev. A 67, 022108 (2003)], Bell inequalities based on correlations between binary digits are considered for a particular entangled state involving 2N trapped ions. These inequalities involve applying displacement operations to half of the ions and then measuring correlations between pairs of corresponding bits in the binary representations of the number of center-of-mass phonons of N particular ions. It is shown that the state violates the inequalities and thus displays nonclassical correlations. It is also demonstrated that it violates a Bell inequality when the displacements are replaced by squeezing operations.

Bright tripartite entanglement in triply concurrent parametric oscillation

We show that an optical parametric oscillator based on three concurrent chi((2)) nonlinearities can produce, above threshold, bright output beams of macroscopic intensities which exhibit strong tripartite continuous-variable entanglement. We also show that there are two ways that the system can exhibit a three-mode form of the Einstein-Podolsky-Rosen paradox, and calculate the extracavity fluctuation spectra that may be measured to verify our predictions.

A profile of middle-aged women who consult a chiropractor or osteopath: Findings from a survey of 11,143 Australian women

Purpose: The aim of this study is to examine the prevalence of chiropractic and osteopathy use and the profile of chiropractor/osteopath users among middle-aged Australian women. Methods: This article reports on research conducted as part of the Australian Longitudinal Study on Women's Health. The focus of this article is the middle-aged women who responded to Survey 3 in 2001 when they were between the ages of 50 and 55 years. The demographic characteristics, health status, and health service use of chiropractic/osteopathy users and nonusers were compared using chi(2) tests for categorical variables and t tests for continuous variables. Results: We estimate that 16% of middle-aged women consult with a chiropractor or osteopath (after adjustment for the oversampling of rural women). Area of residence, education, and employment status were all statistically significantly associated with chiropractic and osteopath use. Specifically, women who live in nonurban areas were more likely to consult a chiropractor or osteopath, compared with women who live in urban areas. Women are significantly more likely to consult with a chiropractor/osteopath if they have had a major personal injury in the previous year, and women who use chiropractic/osteopathy are also high users of 'conventional' health services. Conclusions: Chiropractic/osteopathy use among women in Australia is substantial and cannot be ignored by those providing or managing primary health care services for women. It is essential that the interface and communication between chiropractors/osteopaths and other health care providers be highlighted and maximized to establish and maintain effective overall patient coordination and management.

Quantum computation by communication

We present here a new approach to scalable quantum computing - a 'qubus computer' - which realizes qubit measurement and quantum gates through interacting qubits with a quantum communication bus mode. The qubits could be 'static' matter qubits or 'flying' optical qubits, but the scheme we focus on here is particularly suited to matter qubits. There is no requirement for direct interaction between the qubits. Universal two-qubit quantum gates may be effected by schemes which involve measurement of the bus mode, or by schemes where the bus disentangles automatically and no measurement is needed. In effect, the approach integrates together qubit degrees of freedom for computation with quantum continuous variables for communication and interaction.

Communicating continuous quantum variables between different Lorentz frames

We show how to communicate Heisenberg-limited continuous (quantum) variables between Alice and Bob in the case where they occupy two inertial reference frames that differ by an unknown Lorentz boost. There are two effects that need to be overcome: the Doppler shift and the absence of synchronized clocks. Furthermore, we show how Alice and Bob can share Doppler-invariant entanglement, and we demonstrate that the protocol is robust under photon loss.

Two new tools for assessing patients' knowledge and beliefs about obstructive sleep apnea and continuous positive airway pressure therapy

Background and purpose: Patients' knowledge and beliefs about their illnesses are known to influence a range of health related variables, including treatment compliance. It may, therefore, be important to quantify these variables to assess their impact on compliance, particularly in chronic illnesses such as Obstructive Sleep Apnea (OSA) that rely on self-administered treatments. The aim of this study was to develop two new tools, the Apnea Knowledge Test (AKT) and the Apnea Beliefs Scale (ABS), to assess illness knowledge and beliefs in OSA patients. Patients and methods: The systematic test construction process followed to develop the AKT and the ABS included consultation with sleep experts and OSA patients. The psychometric properties of the AKT and ABS were then investigated in a clinical sample of 81 OSA patients and 33 healthy, non-sleep disordered adults. Results: Results suggest both measures are easily understood by OSA patients, have adequate internal consistency, and are readily accepted by patients. A preliminary investigation of the validity of these tools, conducted by comparing patient data to that of the 33 healthy adults, revealed that apnea patients knew more about OSA, had more positive attitudes towards continuous positive airway pressure (CPAP) treatment, and attributed more importance to treating sleep disturbances than non-clinical groups. Conclusions: Overall, the results of psychometric analyses of these tests suggest these measures will be useful clinical tools with numerous beneficial applications, particularly in CPAP compliance studies and apnea education program evaluations. (C) 2004 Elsevier B.V. All rights reserved.