Effects of Community Exercise Therapy on Metabolic, Brain, Physical, and Cognitive Function Following Stroke : A Randomized Controlled Pilot Trial

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AC Stark shift noise in QND measurement arising from quantum fluctuations of light polarization

In a recent letter [Auzinsh {\it{et. al.}} (physics/0403097)] we have analyzed the noise properties of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement. Such a magnetometer measures spin precession of $N$ atomic spins by detecting optical rotation of far-detuned probe light. Here we consider maximally squeezed probe light, and carry out a detailed derivation of the contribution to the noise in a magnetometric measurement due to the differential AC Stark shift between Zeeman sublevels arising from quantum fluctuations of the probe polarization.Comment: This is a companion note to physics/040309

Wind-blown mosquitoes and introduction of Japanese encephalitis into Australia.

Backtrack simulation analysis indicates that wind-blown mosquitoes could have traveled from New Guinea to Australia, potentially introducing Japanese encephalitis virus. Large incursions of the virus in 1995 and 1998 were linked with low-pressure systems that sustained strong northerly winds from New Guinea to the Cape York Peninsula

Can a quantum nondemolition measurement improve the sensitivity of an atomic magnetometer?

Noise properties of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement are considered. Such a magnetometer measures spin precession of $N$ atomic spins by detecting optical rotation of far-detuned light. Fundamental noise sources include the quantum projection noise and the photon shot-noise. For measurement times much shorter than the spin-relaxation time observed in the absence of light ($\tau_{\rm rel}$) divided by $\sqrt{N}$, the optimal sensitivity of the magnetometer scales as $N^{-3/4}$, so an advantage over the usual sensitivity scaling as $N^{-1/2}$ can be achieved. However, at longer measurement times, the optimized sensitivity scales as $N^{-1/2}$, as for a usual shot-noise limited magnetometer. If strongly squeezed probe light is used, the Heisenberg uncertainty limit may, in principle, be reached for very short measurement times. However, if the measurement time exceeds $\tau_{\rm rel}/N$, the $N^{-1/2}$ scaling is again restored.Comment: Some details of calculations can be found in a companion note: physics/040712

Poor sleep quality and progression of gait impairment in an incident Parkinson’s disease cohort

Abnormal sleep may associate with cognitive decline in Parkinson's disease (PD). Furthermore, sleep dysfunction may associate with worse motor outcome. We hypothesised that PD patients with poor quality sleep would have greater progression in gait dysfunction, due to structural and functional overlap in networks subserving sleep and gait regulation. 12 PD patients and 12 age-matched controls completed longitudinal follow-up over 36 months. Poor sleep efficiency and greater sleep fragmentation correlated significantly with progression of step-width variability, a gait characteristic mediated by postural control, providing evidence that poor sleep in PD is associated with a more rapid deterioration in gait

Hyperpolarized xenon nuclear spins detected by optical atomic magnetometry

We report the use of an atomic magnetometer based on nonlinear magneto-optical rotation with frequency modulated light (FM NMOR) to detect nuclear magnetization of xenon gas. The magnetization of a spin-exchange-polarized xenon sample ($1.7$cm$^3$ at a pressure of $5$bar, natural isotopic abundance, polarization 1%), prepared remotely to the detection apparatus, is measured with an atomic sensor (which is insensitive to the leading field of 0.45 G applied to the sample; an independent bias field at the sensor is $140 \mu$G). An average magnetic field of $\sim 10$nG induced by the xenon sample on the 10-cm diameter atomic sensor is detected with signal-to-noise ratio $\sim 10$, limited by residual noise in the magnetic environment. The possibility of using modern atomic magnetometers as detectors of nuclear magnetic resonance and in magnetic resonance imaging is discussed. Atomic magnetometers appear to be ideally suited for emerging low-field and remote-detection magnetic resonance applications.Comment: 4 pages, 4 figure

Development and validation of risk score for predicting positive repeat prostate biopsy in patients with a previous negative biopsy in a UK population.

BACKGROUND: Little evidence is available to determine which patients should undergo repeat biopsy after initial benign extended core biopsy (ECB). Attempts have been made to reduce the frequency of negative repeat biopsies using PSA kinetics, density, free-to-total ratios and Kattan's nomogram, to identify men more likely to harbour cancer but no single tool accurately predicts biopsy outcome. The objective of this study was to develop a predictive nomogram to identify men more likely to have a cancer diagnosed on repeat prostate biopsy. METHODS: Patients with previous benign ECB undergoing repeat biopsy were identified from a database. Association between age, volume, stage, previous histology, PSA kinetics and positive repeat biopsy was analysed. Variables were entered stepwise into logistic regression models. A risk score giving the probability of positive repeat biopsy was estimated. The performance of this score was assessed using receiver characteristic (ROC) analysis. RESULTS: 110 repeat biopsies were performed in this period. Cancer was detected in 31% of repeat biopsies at Hospital (1) and 30% at Hospital (2). The most accurate predictive model combined age, PSA, PSA velocity, free-to-total PSA ratio, prostate volume and digital rectal examination (DRE) findings. The risk model performed well in an independent sample, area under the curve (AUCROC) was 0.818 (95% CI 0.707 to 0.929) for the risk model and 0.696 (95% CI 0.472 to 0.921) for the validation model. It was calculated that using a threshold risk score of > 0.2 to identify high risk individuals would reduce repeat biopsies by 39% while identifying 90% of the men with prostate cancer. CONCLUSION: An accurate multi-variable predictive tool to determine the risk of positive repeat prostate biopsy is presented. This can be used by urologists in an outpatient setting to aid decision-making for men with prior benign histology for whom a repeat biopsy is being considered.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Unusually large polarizabilities and "new" atomic states in Ba

Electric polarizabilities of four low-J even-parity states and three low-J odd-parity states of atomic barium in the range $35,600$ to $36,000\ $cm$^{-1}$are investigated. The states of interest are excited (in an atomic beam) via an intermediate odd-parity state with a sequence of two laser pulses. The odd-parity states can be excited due to the Stark-induced mixing with even-parity states. The polarizabilities are measured via direct spectroscopy on the second-stage transition. Several states have tensor and scalar polarizabilities that exceed the values that might be expected from the known energy levels of barium by more than two orders of magnitude. Two of the Stark-induced transitions cannot be identified from the known energy spectrum of barium. The observations suggest the existence of as yet unidentified odd-parity energy states, whose energies and angular momenta are determined in the present experiment. A tentative identification of these states as [Xe]$6s8p ^3P_{0,2}$ is suggested.Comment: 29 pages, 12 figure

Exercise Induces Peripheral Muscle But Not Cardiac Adaptations After Stroke: A Randomized Controlled Pilot Trial

Objective To explore the physiological factors affecting exercise-induced changes in peak oxygen consumption and function poststroke. Design Single-center, single-blind, randomized controlled pilot trial. Setting Community stroke services. Participants Adults (N=40; age>50y; independent with/without stick) with stroke (diagnosed >6mo previously) were recruited from 117 eligible participants. Twenty participants were randomized to the intervention group and 20 to the control group. No dropouts or adverse events were reported. Interventions Intervention group: 19-week (3times/wk) progressive mixed (aerobic/strength/balance/flexibility) community group exercise program. Control group: Matched duration home stretching program. Main Outcome Measures (1) Pre- and postintervention: maximal cardiopulmonary exercise testing with noninvasive (bioreactance) cardiac output measurements; and (2) functional outcome measures: 6-minute walk test; timed Up and Go test, and Berg Balance Scale. Results Exercise improved peak oxygen consumption (18±5 to 21±5mL/(kg⋅min); P<.01) and peak arterial-venous oxygen difference (9.2±2.7 to 11.4±2.9mL of O2/100mL of blood; P<.01), but did not alter cardiac output (17.2±4 to 17.7±4.2L/min; P=.44) or cardiac power output (4.8±1.3 to 5.0±1.35W; P=.45). A significant relation existed between change in peak oxygen consumption and change in peak arterial-venous oxygen difference (r=.507; P<.05), but not with cardiac output. Change in peak oxygen consumption did not strongly correlate with change in function. Conclusions Exercise induced peripheral muscle, but not cardiac output, adaptations after stroke. Implications for stroke clinical care should be explored further in a broader cohort