80 research outputs found

    New Phase Transitions in Optimal States for Memory Channels

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    We investigate the question of optimal input ensembles for memory channels and construct a rather large class of Pauli channels with correlated noise which can be studied analytically with regard to the entanglement of their optimal input ensembles. In a more detailed study of a subclass of these channels, the complete phase diagram of the two-qubit channel, which shows three distinct phases is obtained. While increasing the correlation generally changes the optimal state from separable to maximally entangled states, this is done via an intermediate region where both separable and maximally entangled states are optimal. A more concrete model, based on random rotations of the error operators which mimic the behavior of this subclass of channels is also presented.Comment: 13 pages, Late

    Foam-in-Vein: Rheological Characterisation of Liquid Sclerosing Foams Using a Pipe Viscometer

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    Sclerotherapy is one of the most common and least-invasive treatment methods for varicose veins. While bench-top properties of sclerosing foams (e.g., bubble size distribution and foam half-life) have been studied previously, their flow behaviour and its relationship to therapeutic efficacy remain largely uncharacterised. To address this research gap, the present study reports on a novel approach for the rheological characterisation of sclerosing foams aimed at obtaining clinically-applicable data. A pipe viscometry apparatus was employed under conditions that mimic the end-point therapeutic application of foams. Polidocanol (1% v/v) foams of various liquid-to-gas volume ratios (1:3, 1:4 and 1:5) were formulated manually using the Tessari and DSS (double syringe system) methods across a clinically-relevant range of shear rates (≈ 7 s^{-1} – 400 s^{-1}), in polytetrafluoroethylene pipes of different diameters (2.48 mm and 4.48 mm). Additionally, end-effect and wall-slip correction methods were utilised to model the nominal rheology of sclerosing foams. The rheological data were fitted into a power-law model to obtain fluid flow index (n) and fluid consistency index (K) of sclerosing foams, followed by an in-depth statistical analysis of the power-law indices. The observed rheological behaviour of sclerosing foams is shown to be dependent on vessel diameter and liquid-to-gas ratio, while the type of manual formulation technique used appears to be statistically insignificant towards foam rheology. Sclerosing foams behaved as shear-thinning fluids with observed flow indices ranging 0.238 < n < 0.445, while the observed consistency indices ranged 2.977 < K < 12.49. The nominal (end-effect corrected) rheology of foams was shown to follow similar trends concerning liquid-to-gas ratio and formulation technique, independent of the tube diameter. The power-law characterisation of sclerosing foam rheology provided evidence of a quasi-static drainage effect that affected foam viscosity during slower injections. Wall-slip correction failed to provide physically meaningful results and statistical analysis suggested that the type of manual formulation technique used has no impact on the outcome of sclerotherapy on larger varicosities. Overall, results suggest a direct correlation between foam dryness and viscosity. Based on the developed rheological model, this work also demonstrates that low injection flowrates could yield higher therapeutic efficacy in dilated varicose veins

    Turbo-Suppression d'interférences dans un système à étalement de spectre utilisant le codage Spatio-Temporel

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    : On propose dans cet article l'utilisation de codage spatio-temporel pour accroître la capacité d'un système à étalement de spectre et pour aider à la suppression des interférences d'accès multiple (IAM). On étude les performances d'un récepteur multiutilisateurs utilisant des antennes multiples en émission et en réception. On considère ici un système haut débit donc utilisant de faibles facteurs d'étalement conjointement avec une modulation de phase à huit états (MDP-8). Ce genre de système est sujet à des niveaux d' interférences élevés et le but de cet article est de montrer que l'utilisation d'antennes multiples combiné avec l'emploi d'un codage spatio-temporel permet d'obtenir d'excellentes performances et un gain de capacité important même en présence de canaux à évanouissements corrélés et d'effets Doppler élevés. Les codes spatio-temporels employés sont de type STBC (Space-Time Block Code). Une méthode originale pour l'estimation des paramètres de canal sera également présentée

    Radiographic knee osteoarthritis in ex-elite table tennis players

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    <p>Abstract</p> <p>Background</p> <p>Table tennis involves adoption of the semi-flexed knee and asymmetrical torsional trunk movements creating rotational torques on the knee joint which may predispose players to osteoarthritis (OA) of the knee. This study aims to compare radiographic signs of knee OA and associated functional levels in ex-elite male table tennis players and control subjects.</p> <p>Methods</p> <p>Study participants were 22 ex-elite male table tennis players (mean age 56.64 ± 5.17 years) with 10 years of involvement at the professional level and 22 non-athletic males (mean age 55.63 ± 4.08 years) recruited from the general population. A set of three radiographs taken from each knee were evaluated by an experienced radiologist using the Kellgren and Lawrence (KL) scale (0-4) to determine radiographic levels of OA severity. The intercondylar distance was taken as a measure of lower limb angulation. Participants also completed the pain, stiffness, and physical function categories of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) 3.1 questionnaire.</p> <p>Results</p> <p>The results showed 78.3% of the ex-elite table tennis players and 36.3% of controls had varying signs of radiographic knee OA with a significant difference in the prevalence levels of definite radiographic OA (KL scale > 2) found between the two groups (<it>P </it>≤ 0.001). Based on the WOMAC scores, 68.2% of the ex-elite table tennis players reported symptoms of knee pain compared with 27.3% of the controls (<it>p </it>= 0.02) though no significant differences were identified in the mean physical function or stiffness scores between the two groups. In terms of knee alignment, 73.7% of the ex-elite athletes and 32% of the control group had signs of altered lower limb alignment (genu varum) (<it>p </it>= 0.01). Statistical differences were found in subjects categorized as having radiographic signs of OA and altered lower limb alignment (<it>p </it>= 0.03).</p> <p>Conclusions</p> <p>Ex-elite table tennis players were found to have increased levels of radiological signs of OA in the knee joint though this did not transpire through to altered levels of physical disability or knee stiffness in these players when compared with subjects from the general population suggesting that function in these players is not severely impacted upon.</p

    Resting State EEG Biomarkers of Cognitive Decline (PLOS ONE - INSPECDS)

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    Supporting data for the manuscript titled: Resting State EEG Biomarkers of Cognitive Decline Associated with Alzheimer’s Disease and Mild Cognitive Impairmen

    EEG signatures of contextual influences on visual search with real scenes

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    Raw data acquired for the research work on &quot;EEG signatures of contextual influences on visual search with real scenes&quot; at VIU Lab at University of California Santa BarbaraTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

    Resting State EEG Biomarkers of Cognitive Decline (PLOS ONE - INSPECDS)

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    Supporting data for the manuscript titled: Resting State EEG Biomarkers of Cognitive Decline Associated with Alzheimer’s Disease and Mild Cognitive Impairmen

    Resting State EEG Biomarkers of Cognitive Decline (PLOS ONE - INSPECDS)

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    Supporting data for the manuscript titled: Resting State EEG Biomarkers of Cognitive Decline Associated with Alzheimer’s Disease and Mild Cognitive Impairmen
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