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Samo Lasi
Filip Szczepankiewicz Erica Dall'Armellina Arka Das Christopher Kelly Sven Plein Jürgen E. Schneider Markus Nilsson Irvin Teh 《NMR in biomedicine》2020,33(2)
Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed. 相似文献
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The test–retest reliability of the Incontinence Questionnaire‐Urinary Incontinence Short Form (ICIQ‐UI SF) for assessing type of urinary incontinence in males and females 下载免费PDF全文
Edmond PH Choi RN MPhil BNurs Cindy LK Lam MD MBBS FHKAM Weng Yee Chin MBBS FRACGP 《Journal of clinical nursing》2015,24(23-24):3742-3744
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Nittaya Phanuphak Nipat Teeratakulpisarn Frits van Griensven Nitiya Chomchey Suteeraporn Pinyakorn James LK Fletcher Rapee Trichavaroj Supanit Pattanachaiwit Nelson Michael Praphan Phanuphak Jerome H Kim Jintanat Ananworanich 《Journal of the International AIDS Society》2015,18(1)
Introduction
HIV transmission risk is highest during acute HIV infection (AHI). We evaluated HIV RNA in the anogenital compartment in men who have sex with men (MSM) during AHI and compared time to undetectable HIV RNA after three-drug versus five-drug antiretroviral therapy (ART) to understand risk for onward HIV transmission.Methods
MSM with AHI (n=54) had blood, seminal plasma and anal lavage collected for HIV RNA at baseline, days 3 and 7, and weeks 2, 4, 12 and 24. Data were compared between AHI stages: 1 (fourth-generation antigen-antibody combo immunoassay [IA]–, third-generation IA–, n=15), 2 (fourth-generation IA+, third-generation IA–, n=9) and 3 (fourth-generation IA+, third-generation IA+, western blot–/indeterminate, n=30) by randomization to five-drug (tenofovir+emtricitabine+efavirenz+raltegravir+maraviroc, n=18) versus three-drug (tenofovir+emtricitabine+efavirenz, n=18) regimens.Results
Mean age was 29 years and mean duration since HIV exposure was 15.4 days. Mean baseline HIV RNA was 5.5 in blood, 3.9 in seminal plasma and 2.6 log10 copies/ml in anal lavage (p<0.001). Blood and seminal plasma HIV RNA were higher in AHI Stage 3 compared to Stage 1 (p<0.01). Median time from ART initiation to HIV RNA <50 copies/ml was 60 days in blood, 15 days in seminal plasma and three days in anal lavage. Compared with the three-drug ART, the five-drug ART had a shorter time to HIV RNA <1500 copies/ml in blood (15 vs. 29 days, p=0.005) and <50 copies/ml in seminal plasma (13 vs. 24 days, p=0.048).Conclusions
Among MSM with AHI, HIV RNA was highest in blood, followed by seminal plasma and anal lavage. ART rapidly reduced HIV RNA in all compartments, with regimen intensified by raltegravir and maraviroc showing faster HIV RNA reductions in blood and seminal plasma. 相似文献7.
The association between stress and health has been well researched in the past; however, comparatively few mediators have been tested to understand the underlying mechanism. With increasing awareness on mental well‐being, this study evaluated the relationship between perceived stress and perceived health and examined mental well‐being as a mediator. Two‐hundred undergraduates aged 21 to 26 years completed the English Perceived Stress Scale, Health Status Questionnaire and Asian Mental Well‐Being Scale that assess perceived stress, perceived health and mental well‐being, respectively. Factor analysis and structural equation modelling on the Perceived Stress Scale replicated the reported two‐factor structure after excluding an insignificant item. Linear multiple regression analyses indicated that perceived stress was negatively associated with perceived health. Results showed that mental well‐being partially mediated the relationship between perceived stress and perceived health, although it is acknowledged that this association could be bidirectional. Findings from the present study suggest that future research could focus on reducing stress and improving mental well‐being to alleviate the effect of stress on health. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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The in vitro pH changes in root dentin over a period of 2 weeks was investigated in 48 extracted bicuspids after intracanal placement of either Roeko Calcium Hydroxide Plus Points, aqueous calcium hydroxide paste, or gutta-percha points (control group) after root canal preparation. Microelectrodes were placed in outer and inner root dentin at cervical, middle, and apical thirds of the root to measure the pH at 1 h, 2 h, 3 h, 1 day, 3 days, 7 days, and 14 days. Roeko Calcium Hydroxide Plus Points reached a peak inner dentine pH of 11.67 and a peak outer dentine pH of 10.82 at 3 h. In addition, Roeko Calcium Hydroxide Plus Points maintained an outer dentine pH above 9.5 for approximately 2 days, whereas the aqueous calcium hydroxide paste did not reach this pH. However, the alkalinity in dentin with Roeko Calcium Hydroxide Plus Points was maintained for 7 days only, whereas aqueous calcium hydroxide paste maintained an alkaline environment throughout the 2-week period. 相似文献
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