20 research outputs found

    The photometric observation of the quasi-simultaneous mutual eclipse and occultation between Europa and Ganymede on 22 August 2021

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    Mutual events (MEs) are eclipses and occultations among planetary natural satellites. Most of the time, eclipses and occultations occur separately. However, the same satellite pair will exhibit an eclipse and an occultation quasi-simultaneously under particular orbital configurations. This kind of rare event is termed as a quasi-simultaneous mutual event (QSME). During the 2021 campaign of mutual events of jovian satellites, we observed a QSME between Europa and Ganymede. The present study aims to describe and study the event in detail. We observed the QSME with a CCD camera attached to a 300-mm telescope at the Hong Kong Space Museum Sai Kung iObservatory. We obtained the combined flux of Europa and Ganymede from aperture photometry. A geometric model was developed to explain the light curve observed. Our results are compared with theoretical predictions (O-C). We found that our simple geometric model can explain the QSME fairly accurately, and the QSME light curve is a superposition of the light curves of an eclipse and an occultation. Notably, the observed flux drops are within 2.6% of the theoretical predictions. The size of the event central time O-Cs ranges from -14.4 to 43.2 s. Both O-Cs of flux drop and timing are comparable to other studies adopting more complicated models. Given the event rarity, model simplicity and accuracy, we encourage more observations and analysis on QSMEs to improve Solar System ephemerides.Comment: 23 pages, 5 appendixes, 16 figures, 7 table

    A study of Sun Qifeng, 1585-1675

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    published_or_final_versionChinese Historical StudiesMasterMaster of Art

    Palladium(II)-Catalyzed othro-C–H-Benzoxylation of 2-Arylpyridines by Oxidative Coupling with Aryl Acylperoxides

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    A palladium(II)-catalyzed ortho-benzoxylation of 2-arylpyridines with aryl acylperoxides was developed. With pyridyl as directing group, the benzoxylation reaction exhibits remarkable regioselectivity and excellent functional group tolerance, providing the products in up to 87% yield

    Acupuncture for Poststroke Dysphagia: A Pilot, Nonrandomized, Self-Controlled Trial

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    Objective. To evaluate the effectiveness and safety of acupuncture treatment for dysphagia as a complication of stroke. Methods and Design. This is a multicenter, pragmatic, nonrandomized, self-controlled clinical trial. A total of 39 patients were recruited from several Chinese medicine outpatient clinics and hospital-affiliated speech therapy outpatient clinics in Hong Kong. 26 patients completed all the 24 sessions of acupuncture treatment within two months, and only 12 of them were used as self-control. For the self-control group, the retrospective clinical data was taken from the electronic patient records with patient consent. The descriptive swallowing function data were converted into the quantitative Royal Brisbane Hospital Outcome Measure for Swallowing (RBHOMS) scores by two registered speech therapists through a validation process. And the data were validated by reaching consensus between the two speech therapists. All subjects underwent a baseline assessment before commencement of treatment, and outcome assessments were conducted upon the completion of treatment. The primary outcome measure is the RBHOMS score, which is a swallowing disability rating scale for monitoring difficulties in daily swallowing function. Secondary outcome measures include the Chinese version of the Swallow Quality-of-Life Questionnaire and adverse events. All the primary and secondary outcomes were assessed at baseline as well as at the end of acupuncture treatment (month 2). Results. A total of 39 participants aged 46 to 89 years were enrolled in the study, and the male-to-female ratio was 15 : 11. The mean baseline RBHOMS score of all 39 participants was 5.92 ± 2.23. The mean retrospective RBHOMS score of the 12 subjects who were used as self-control was 5.67 ± 1.72 before enrollment, while the mean RBHOMS score of the 26 participants who completed all the 24 sessions of treatment was 6.92 ± 2.07. There were statistically significant differences between the RBHOMS score at the completion of treatment and baseline (p=0.006), and retrospective data (p=0.042). Moreover, a significant difference was also found in terms of swallow quality-of-life score before and after acupuncture treatment (p<0.01). Conclusions. This pilot study provides preliminary evidence for the effectiveness of acupuncture for poststroke dysphagia. The findings from this trial can be used as a foundation for future full-scale randomized controlled clinical trials to assess the efficacy and safety of acupuncture for poststroke dysphagia. Ethics and Dissemination. The ethical approval of the clinical research study was granted by the Research Ethics Committee of both New Territories East and West Cluster of Hong Kong. Written informed consent was obtained from all participants, and the study was undertaken according to the ICH-GCP Guidelines. Trial Registration. This trial is registered with ChiCTR-TRC-12002621 and the registration date is 2012-10-26
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