The analytic radial acceleration relation for galaxy clusters

Recently, a tight correlation between the dynamical radial acceleration and the baryonic radial acceleration in galaxies - the radial acceleration relation - has been discovered. This has been claimed as an indirect support of the modified gravity theories. However, whether the radial acceleration relation could also be found in galaxy clusters is controversial. In this article, we derive and present an analytic radial acceleration relation for the central region of galaxy clusters. We examine the data of some large galaxy clusters and we find that the resulting radial acceleration relation has a very large scatter. Moreover, although the radial acceleration relation for galaxy clusters shows some agreement with the one discovered in galaxies for a certain range of baryonic radial acceleration, their functional forms are somewhat different from each other. This suggests that the radial acceleration relation may not be a universal relation in general.Comment: Accepted in Phys. Rev.

A severe challenge to the MOND phenomenology in our Galaxy

Modified Newtonian Dynamics (MOND) is one of the most popular alternative theories of dark matter to explain the missing mass problem in galaxies. Although it remains controversial regarding MOND as a fundamental theory, MOND phenomenology has been shown to widely apply in different galaxies, which gives challenges to the standard $\Lambda$ cold dark matter model. In this article, we derive analytically the galactic rotation curve gradient in the MOND framework and present a rigorous analysis to examine the MOND phenomenology in our Galaxy. By assuming a benchmark baryonic disk density profile and two popular families of MOND interpolating functions, we show for the first time that the recent discovery of the declining Galactic rotation curve in the outer region ($R \approx 17-23$ kpc) can almost rule out the MOND phenomenology at more than $5\sigma$. This strongly supports some of the previous studies claiming that MOND is neither a fundamental theory nor a universal description of galactic properties.Comment: Accepted in Ap

Senior year = 高三

Film Director: Zhou Hao (周浩) Film Release Year: 2005https://commons.ln.edu.hk/ccs_worksheet/1008/thumbnail.jp

Walking for transportation in Hong Kong Chinese urban elders: a cross-sectional study on what destinations matter and when

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Key factors in encouraging and empowering undergraduates to practice service leadership through extra-curricular service-learning practicums

While internships bridge students\u27 academic major to the world of work, in this paper, we focus on practicums as vehicles for service leadership development. In the summers of 2013 and 2014, Lingnan University arranged 28 full-time practicums in 13 partner organizations, mainly not-for-profit organizations or social enterprises, for students with prior service-learning experience. Practicums lasted 6 weeks in 2013, and 8 weeks in 2014. Students attended a 3-hour preparatory workshop on service leadership, and an interim review meeting. Through interviews with 26 practicum students and site supervisors from 13 partner organizations, we identified three factors that enabled practicum students to develop as service leaders. The first factor was the availability of practicum tasks that required innovation to identify and meet hitherto unmet needs. Successful practicums allowed students to create or extend events or arrangements that made a clear difference to the achievement of the social mission of their respective host organizations. Students were empowered to initiate responsibility for service planning, organization and delivery, including the need to anticipate and respond to end -user contingencies and demands. The second broad factor was the availability of a supportive site supervisor, willing and able to provide timely briefings, guidance, coaching and feedback. The third factor was the developmental readiness of the practicum student. Developmentally -ready students were psychologically prepared to seek out new challenges, cared about both end-user service-recipients and other stakeholders, were committed to making a difference, and had sufficient skills, knowledge, and self-confidence to work things out independently and arrive at their own decisions. They found effective ways to approach their site supervisor whenever necessary, and by demonstrating their competence and integrity, they were able to build trust. We highlight four cases, which reveal differences between traditional internships and the innovation -oriented nature of successful service leadership practicums. The first features a supportive site supervisor and two developmentally-ready practicum students. The second involves a moderately-supportive site supervisor, one developmentally-ready practicum student, and one moderately-ready practicum student. The third features a supportive site supervisor, one developmentally-ready practicum student, and one moderately-ready practicum student. The fourth involves a less-supportive site supervisor and a less-ready practicum student

Use of switching barriers to retain customers: Online retail stock traders in Hong Kong

Why some customers decide to stay withexisting service provider after having thought of switchinghas apparently not been examined adequately in extantresearch. The purpose of this research is to identifyfactors relevant to building constructs to representswitching barriers in online retail stock trading industryin Hong Kong. Review of extant literature, development ofa questionnaire and focus group interviews are the threeprincipal methods used for this research. Four factors thatare relevant for measuring switching barriers areidentified: two positive barriers involve service recoveryand trust and two negative barriers relate to higherswitching costs and lack of attractive alternatives

Lipid levels and major adverse cardiovascular events in patients initiated on statins for primary prevention: an international population-based cohort study protocol

Background : Clinical guidelines recommend specific targets for low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol (non-HDL-C) for primary prevention of cardiovascular disease (CVD). Furthermore, individual variability in lipid response to statin therapy requires assessment of the association in diverse populations. Aim: To assess whether lower concentrations of LDL-C and non-HDL-C are associated with a reduced risk of major adverse cardiovascular events (MACE) in primary prevention of CVD. Design & setting: An international, new-user, cohort study will be undertaken. It will use data from three electronic health record databases from three global regions: Clinical Practice Research Datalink, UK; PREDICT-CVD, New Zealand (NZ); and the Clinical Data and Analysis Reporting System, Hong Kong (HK). Method: New statin users without a history of atherosclerotic CVD, heart failure, or chronic kidney disease, with baseline and follow-up lipid levels will be eligible for inclusion. Patients will be classified according to LDL-C (<1.4, 1.4–1.7, 1.8–2.5, and ≥2.6 mmol/l) and non-HDL-C (<2.2, 2.2–2.5, 2.6–3.3, and ≥3.4 mmol/l) concentrations 24 months after initiating statin therapy. The primary outcome of interest is MACE, defined as the first occurrence of coronary heart disease, stroke, or cardiovascular death. Secondary outcomes include all-cause mortality and the individual components of MACE. Sensitivity analyses will be conducted using lipid levels at 3 and 12 months after starting statin therapy. Conclusion: Results will inform clinicians about the benefits of achieving guideline recommended concentrations of LDL-C for primary prevention of CVD

Qigong Exercise Alleviates Fatigue, Anxiety, and Depressive Symptoms, Improves Sleep Quality, and Shortens Sleep Latency in Persons with Chronic Fatigue Syndrome-Like Illness

Objectives:. To evaluate the effectiveness of Baduanjin Qigong exercise on sleep, fatigue, anxiety, and depressive symptoms in chronic fatigue syndrome- (CFS-) like illness and to determine the dose-response relationship. Methods:. One hundred fifty participants with CFS-like illness (mean age = 39.0, SD = 7.9) were randomly assigned to Qigong and waitlist. Sixteen 1.5-hour Qigong lessons were arranged over 9 consecutive weeks. Pittsburgh Sleep Quality Index (PSQI), Chalder Fatigue Scale (ChFS), and Hospital Anxiety and Depression Scale (HADS) were assessed at baseline, immediate posttreatment, and 3-month posttreatment. The amount of Qigong self-practice was assessed by self-report. Results:. Repeated measures analyses of covariance showed a marginally nonsignificant (P = 0.064) group by time interaction in the PSQI total score, but it was significant for the “subjective sleep quality” and “sleep latency” items, favoring Qigong exercise. Improvement in “subjective sleep quality” was maintained at 3-month posttreatment. Significant group by time interaction was also detected for the ChFS and HADS anxiety and depression scores. The number of Qigong lessons attended and the amount of Qigong self-practice were significantly associated with sleep, fatigue, anxiety, and depressive symptom improvement. Conclusion:. Baduanjin Qigong was an efficacious and acceptable treatment for sleep disturbance in CFS-like illness. This trial is registered with Hong Kong Clinical Trial Register: HKCTR-1380