General analysis on the use of tesla's resonators in domino forms for wireless power transfer

In this paper, we present a brief overview of historical developments of wireless power and an analysis on the use of Tesla's resonators in domino forms for wireless power transfer. Relay resonators are spaced between the transmitter and receiver coils with the objectives of maximizing energy efficiency and increasing the overall transmission distance between the power source and the load. Analytical expressions for the optimal load and maximum efficiency at resonance frequency are derived. These equations are verified with practical measurements obtained from both coaxial and noncoaxial domino resonator systems. To avoid the use of high operating frequency for wireless power transfer in previous related research, the technique presented here can be used at submegahertz operation so as to minimize the power loss in both the power supply and the output stage. We demonstrated both theoretically and practically that unequal spacing for the coaxial straight domino systems has better efficiency performance than the equal-spacing method. Also, the flexibility of using resonators in various domino forms is demonstrated. © 2012 IEEE.published_or_final_versio

A study of consumer protection law in Hong Kong

Consumption of goods and services is inevitable in our daily life. So consumer protection is essential for every consumer. However, the existing consumer protection system in Hong Kong is not comprehensive enough to protect consumers. Thus, this project concentrates on studying the consumer protection law in Hong Kong to evaluate its sufficiency for protecting consumers. Besides, we also investigate the Hong Kong consumer protection system, including the functions and powers of the Consumer Council, and make compare it with Australia’s consumer protection system. The Consumer Council is the only statutory consumer protection body in Hong Kong. It is not an independent unit in its operation. Moreover, it lacks investigative, legislative and enforcement powers. Furthermore, the laws and ordinances are not sufficient and comprehensive enough to protect all consumers. Most importantly, the government’s attitude towards consumer protection is non-interventionist. After a comparison is made with the Australia’s system, we discover that Australia’s consumer protection body, the National Consumer Affairs Advisory Council, is a purely advisory body to deal with the matters about consumer protection. It is independent from the other non-government consumer organizations, such as the Trade Practices Commission. Not only does it have investigative, legislative and enforcement power, it also has a comprehensive competition policy to protect consumers. Due to the lack of the consumer protection law in Hong Kong, we recommend that other developed countries’ consumer protection systems, such as Australia, should be used as an example to improve our consumer protection system. The comprehensive competition policy, including competition laws and authority, should be introduced in order to ensure that more consumers could be in the protective net. Besides, the Consumer Council should be given more powers to operate and deal with the consumer problems. In addition, the government should do more for consumer protection. It can be done by increasing the resources to the Consumer Council and educating the public about their consumer rights. Most importantly, the Consumer Council should act independently to achieve its objectives on consumer protection. Thus, all consumers can be better protected under these improvements

Identifying risks in China's counter-terrorism policy

published_or_final_versionInternational and Public AffairsMasterMaster of International and Public Affair

Combining CD4 recovery and CD4: CD8 ratio restoration as an indicator for evaluating the outcome of continued antiretroviral therapy: an observational cohort study

Immune recovery following highly active antiretroviral therapy (HAART) is commonly assessed by the degree of CD4 reconstitution alone. In this study, we aimed to assess immune recovery by incorporating both CD4 count and CD4:CD8 ratio

Rotation in Event Horizon Telescope Movies

The Event Horizon Telescope (EHT) has produced images of M87* and Sgr A*, and will soon produce time sequences of images, or movies. In anticipation of this, we describe a technique to measure a rotation rate, or pattern speed $\Omega_p$, from movies using an autocorrelation technique. We validate the technique on Gaussian random field models with a known rotation rate and apply it to a library of synthetic images of Sgr A* based on general relativistic magnetohydrodynamics (GRMHD) simulations. We predict that EHT movies will have $\Omega_p \approx 1$ degree per $\mathrm{GMc^{-3}}$, which is of order $15\%$ of the Keplerian orbital frequency in the emitting region. We can plausibly attribute the slow rotation seen in our models to the pattern speed of inward-propagating spiral shocks. We also find that $\Omega_p$ depends strongly on inclination. Application of this technique will enable us to compare future EHT movies with the clockwise rotation of Sgr A* seen in near-infrared flares by GRAVITY. Pattern speed analysis of future EHT observations of M87* and Sgr A* may also provide novel constraints on black hole inclination and spin, as well as an independent measurement of black hole mass

Impact of intravenous vitamin C as a monotherapy on mortality risk in critically ill patients: A meta-analysis of randomized controlled trials with trial sequential analysis

BackgroundThis meta-analysis aimed at investigating the pooled evidence regarding the effects of intravenous vitamin C (IVVC) on mortality rate in critically ill patients.MethodsDatabases including Medline, Embase, and Cochrane Library were searched from inception to October, 2022 to identify RCTs. The primary outcome was the risk of overall mortality. Subgroup analyses were performed based on IVVC dosage (i.e., cut-off value: 100 mg/kg/day or 10000 mg/day). Trial sequential analysis (TSA) was used to examine the robustness of evidence.ResultsA total of 12 trials including 1,712 patients were analyzed. Although meta-analysis demonstrated a lower risk of mortality in patients with IVVC treatment compared to those without [risk ratio (RR): 0.76, 95% CI: 0.6 to 0.97, p = 0.02, I2 = 36%, 1,711 patients), TSA suggested the need for more studies for verification. Moreover, subgroup analyses revealed a reduced mortality risk associated with a low IVVC dosage (RR = 0.72, p = 0.03, 546 patients), while no beneficial effect was noted with high IVVC dosage (RR = 0.74, p = 0.13, I2 = 60%, 1,165 patients). The durations of vasopressor [mean difference (MD): −37.75 h, 404 patients) and mechanical ventilation (MD: −47.29 h, 388 patients) use were shorter in the IVVC group than those in the controls, while there was no significant difference in other prognostic outcomes (e.g., length of stay in intensive care unit/hospital) between the two groups.ConclusionAlthough intravenous vitamin C as a monotherapy reduced pooled mortality, durations of vasopressor use and mechanical ventilation, further research is required to support our findings and to identify the optimal dosage of vitamin C in the critical care setting.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/, identifier CRD42022371090

Impact of a delayed second dose of mRNA vaccine (BNT162b2) and inactivated SARS-CoV-2 vaccine (CoronaVac) on risks of all-cause mortality, emergency department visit, and unscheduled hospitalization

BACKGROUND: Safety after the second dose of the SARS-CoV-2 vaccine remains to be elucidated, especially among individuals reporting adverse events after their first dose. This study aims to evaluate the impact of a delayed second dose on all-cause mortality and emergency services. METHODS: A territory-wide, retrospective cohort of people who had completed two doses of mRNA (BNT162b2) or inactivated SARS-CoV-2 (CoronaVac) vaccine between February 23 and July 3, 2021, in Hong Kong was analyzed, with linkage to electronic health records retrieved from the Hong Kong Hospital Authority. Vaccine recipients were classified as receiving a second dose within recommended intervals (21-28 days for BNT162b2; 14-28 days for CoronaVac) or delayed. Study outcomes were all-cause mortality, emergency department (ED) visits, and unscheduled hospitalizations within 28 days after the second dose of vaccination. RESULTS: Among 417,497 BNT162b2 and 354,283 CoronaVac second dose recipients, 3.8% and 28.5% received the second dose beyond the recommended intervals (mean 34.4 and 31.8 days), respectively. During the study period, there were < 5 daily new cases of COVID-19 infections in the community. Delaying the second dose was not associated with all-cause mortality (hazard ratio [HR] = 1.185, 95% CI 0.478-2.937, P = 0.714), risk of ED visit (HR = 0.966, 95% CI 0.926-1.008, P = 0.113), and risk of unscheduled hospitalization (HR = 0.956, 95% CI 0.878-1.040, P = 0.294) compared to that within the recommended interval for CoronaVac recipients. No statistically significant differences in all-cause mortality (HR = 4.438, 95% CI 0.951-20.701, P = 0.058), ED visit (HR = 1.037, 95% CI 0.951-1.130, P = 0.411), and unscheduled hospitalization (HR = 1.054, 95% CI 0.867-1.281, P = 0.597) were identified between people who received a second dose of BNT162b2 within and beyond the recommended intervals. CONCLUSIONS: No significant association between delayed second dose of BNT162b2 or CoronaVac and all-cause mortality, ED visit, and unscheduled hospitalization was observed in the present cohort. Regardless of the recommended or delayed schedule for SARS-CoV-2 vaccination, a second dose of both vaccines should be administered to obtain better protection against infection and serious disease. The second dose should be administered within the recommended interval following the manufacturer's product information, until further studies support the benefits of delaying vaccination outweighing the risks

Prediction model for short-term mortality after palliative radiotherapy for patients having advanced cancer: a cohort study from routine electronic medical data.

We developed a predictive score system for 30-day mortality after palliative radiotherapy by using predictors from routine electronic medical record. Patients with metastatic cancer receiving first course palliative radiotherapy from 1 July, 2007 to 31 December, 2017 were identified. 30-day mortality odds ratios and probabilities of the death predictive score were obtained using multivariable logistic regression model. Overall, 5,795 patients participated. Median follow-up was 39.6 months (range, 24.5-69.3) for all surviving patients. 5,290 patients died over a median 110 days, of whom 995 (17.2%) died within 30 days of radiotherapy commencement. The most important mortality predictors were primary lung cancer (odds ratio: 1.73, 95% confidence interval: 1.47-2.04) and log peripheral blood neutrophil lymphocyte ratio (odds ratio: 1.71, 95% confidence interval: 1.52-1.92). The developed predictive scoring system had 10 predictor variables and 20 points. The cross-validated area under curve was 0.81 (95% confidence interval: 0.79-0.82). The calibration suggested a reasonably good fit for the model (likelihood-ratio statistic: 2.81, P = 0.094), providing an accurate prediction for almost all 30-day mortality probabilities. The predictive scoring system accurately predicted 30-day mortality among patients with stage IV cancer. Oncologists may use this to tailor palliative therapy for patients

The Effect of Alcohol Intoxication on Mortality of Blunt Head Injury

Alcohol is found to have neuroprotection in recent studies in head injuries. We investigated the association of blood alcohol concentration (BAC) with mortality of patients with blunt head injury after traffic accident. All patients sustaining blunt head injury caused by traffic accident brought to our emergency department who had obtained a brain computed tomography scans and BAC were analyzed. Patients with unknown mechanisms, transfers from outside hospitals, and incomplete data were excluded. Logistic regression was used to identify independent predictors of mortality. During the study period, 3,628 patients with brain computed tomography (CT) were included. Of these, BAC was measured in 556 patients. Patients with the lowest BAC (less than 8 mg/dl) had lower mortality; intoxicated patients with BAC between 8 and less than 100 mg/dl were associated with significantly higher mortality than those patients in other intoxicated groups. Adjusted logistic regression demonstrated higher BAC group and Glasgow coma scale (GCS) scores, and lower ISS and age were identified as independent predictors of reduced mortality. In our study, we found that patients who had moderate alcohol intoxication had higher risk of mortality. However, higher GCS scores, lower ISS, and younger age were identified as independent predictors of reduced mortality in the study patients