Applying Theories of Particle Packing and Rheology to Concrete for Sustainable Development

Concrete is one of the most important construction materials. However, it is not so compatible with the demands of sustainable development because manufacturing of cement generates a large amount of carbon dioxide and therefore cement consumption produces a huge carbon footprint. Currently, the cement consumption is generally lowered by adding supplementary cementitious materials to replace part of the cement. Nonetheless, in order to maintain performance, there is a limit to such cement replacement by supplementary cementitious materials. To further reduce the cement consumption, the total cementitious materials content has to be reduced. This requires the packing density of the aggregate particles to be maximized so that the amount of voids in the bulk volume of aggregate to be filled with cement paste could be minimized and the surface area of the aggregate particles to be minimized so that the amount of cement paste needed to form paste films coating the surfaces of aggregate particle for rheological performance could be minimized. Such optimization is not straightforward and modern concrete science based on particuology is needed. Herein, a number of new theories regarding particle packing and rheology of concrete, which are transforming conventional concrete technology into modern concrete science, are presented. These theories would help to develop a more scientific and systematic concrete mix design method for the production of high-performance concrete with minimum cement consumption

Do Low Preoperative Vitamin D Levels Reduce the Accuracy of Quick Parathyroid Hormone in Predicting Postthyroidectomy Hypocalcemia?

BACKGROUND: Although some studies have suggested that low preoperative 25-hydroxyvitamin D (25-OHD) levels may increase the risk of hypocalcemia and decrease the accuracy of single quick parathyroid hormone in predicting hypocalcemia after total thyroidectomy, the literature remains scarce and inconsistent. Our study aimed to address these issues. METHODS: Of the 281 consecutive patients who underwent a total/completion total thyroidectomy, 244 (86.8 %) did not require any oral calcium and/or calcitriol supplements (group 1), while 37 (13.2 %) did (group 2) at hospital discharge. 25-OHD level was checked 1 day before surgery, and postoperative quick parathyroid hormone (PTH) was checked at skin closure (PTH-SC). Postoperative serum calcium was checked regularly. Hypocalcemia was defined by the presence of symptoms or adjusted calcium of <1.90 mmol/L. Significant factors for hypocalcemia were determined by univariate and multivariate analyses. The accuracy of PTH-SC in predicting hypocalcemia was measured by area under a receiver operating characteristic curve (AUC), and the AUC of PTH-SC was compared between patients with preoperative 25-OHD <15 and ≥15 ng/mL via bootstrapping. RESULTS: Preoperative 25-OHD level was not significantly different between groups 1 and 2 (13.1 vs. 12.5 ng/mL, p = 0.175). After adjusting for other significant factors, PTH-SC (odds ratio 2.49, 95 % confidence interval 1.52–4.07, p < 0.001) and parathyroid autotransplantation (odds ratio 3.23, 95 % confidence interval 1.22–8.60, p = 0.019) were the two independent factors for hypocalcemia. The AUC of PTH-SC was similar between those with 25-OHD <15 and ≥15 ng/mL (0.880 vs. 0.850, p = 0.61) CONCLUSIONS: Low 25-OHD was not a significant factor for hypocalcemia and did not lower the accuracy of quick PTH in predicting postthyroidectomy hypocalcemia

Physical activity as a modifiable risk factor for periodontal disease

Non-communicable diseases (NCDs), which contribute significantly to global morbidity, are largely preventable through behavioral changes. As with other NCDs, periodontitis is associated with modifiable risk factors such as smoking and stress and is linked to multiple adverse health outcomes through a shared pathway of chronic systemic inflammation. While the health benefits of physical activity have been widely promoted in public health and extensively studied for other systemic conditions, its impact on periodontal health has only recently started to gain attention. This article critically evaluates the current literature on the relationship between physical activity and periodontitis. While cross-sectional studies have shown an inverse association between physical activity levels and periodontitis risk in the general population, clinical oral health surveys of elite athletes with high levels of physical activity have nonetheless revealed poor periodontal conditions. Although causality has not been determined, physical activity could positively impact periodontitis directly, by reducing inflammatory biomarkers, and indirectly, through its modulatory effects on insulin sensitivity, obesity, bone density, stress, and other health promoting behaviors. Given the importance of risk factor control during initial periodontal therapy, understanding the role of physical activity as a potential behavioral risk modifier is paramount. The findings of this review provide an evidence-based overview of how physical activity could influence periodontitis. There is a need for longitudinal cohort studies to verify the temporality of the reported associations and exclude confounders, while interventions are needed to assess the efficacy of physical activity on periodontal treatment outcomes

Transmission dynamics, serial interval and epidemiology of COVID-19 diseases in Hong Kong under different control measures

Background: The outbreak of coronavirus disease 2019 (COVID-19) started in Wuhan, China in late December 2019, and subsequently became a pandemic. Hong Kong had implemented a series of control measures since January 2020, including enhanced surveillance, isolation and quarantine, border control and social distancing. Hong Kong recorded its first case on 23 January 2020, who was a visitor from Wuahn. We analysed the surveillance data of COVID-19 to understand the transmission dynamics and epidemiology in Hong Kong. Methods: Based on cases recorded from 23 January to 6 April 2020, we constructed the epidemic curve of daily COVID-19 incidence and used this data to estimate the time-varying reproduction number ( R t ) with the R package EpiEstim, with serial interval computed from local data. We described the demographic and epidemiological characteristics of reported cases. We computed weekly incidence by age and residential district to understand the spatial and temporal transmission of the disease. Results: COVID-19 disease in Hong Kong was characterised with local cases and clusters detected after two waves of importations, first in late January and the second one in early March. The R t increased to approximately 2 and approximately 1, respectively, following these importations; it decreased to below 1 afterwards, which coincided with the implementation, modification and intensification of different control measures. Compared to local cases, imported cases were younger (mean age: 52 years among local cases vs 35 years among imported cases), had a lower proportion of underlying disease (9% vs 5%) and severe outcome (13% vs 5%). Cases were recorded in all districts but the incidence was highest in those in the Hong Kong Island region. Conclusions: Stringent and sustained public health measures at population level could contain the COVID-19 disease at a relatively low level

Association between the risk of seizure and COVID-19 vaccinations: A self-controlled case-series study

OBJECTIVE: The risk of seizure following BNT162b2 and CoronaVac vaccinations has been sparsely investigated. This study aimed to evaluate this association. METHOD: Patients who had their first seizure-related hospitalization between February 23, 2021 and January 31, 2022 were identified in Hong Kong. All seizure episodes happening on the day of vaccination (day 0) were excluded since clinicians validated that most of the cases on day 0 were syncopal episodes. Within-individual comparison using a modified self-controlled case series analysis was applied to estimate the incidence rate ratio (IRR) with 95% confidence intervals (CI) of seizure using conditional Poisson regression. RESULTS: We identified 1656 individuals who had their first seizure-related hospitalization (BNT162b2: 426; CoronaVac: 263; unvaccinated: 967) within the observation period. The incidence of seizure was 1.04 (95% CI: 0.80-1.33) and 1.11 (95% CI: 0.80-1.50) per 100,000 doses of BNT162b2 and CoronaVac administered respectively. 16 and 17 individuals received second dose after having first seizure within 28 days after first dose of BNT162b2 and CoronaVac vaccinations, respectively. None had recurrent seizures after the second dose. There was no increased risk during day 1-6 after the first (BNT162b2: IRR=1.39, 95% CI=0.75-2.58; CoronaVac: IRR=1.19, 95% CI=0.50-2.83) and second doses (BNT162b2: IRR=1.36, 95% CI 0.72-2.57; CoronaVac: IRR=0.71, 95% CI=0.22-2.30) of vaccinations. During 7-13, 14-20- and 21-27-days post-vaccination, no association was observed for both vaccines. SIGNIFICANCE: The findings demonstrated no increased risk of seizure following BNT162b2 and CoronaVac vaccinations. Future studies will be warranted to evaluate the risk of seizure following COVID-19 vaccinations in different populations with subsequent doses to ensure the generalizability

Efficacy, safety and immunogenicity of a human rotavirus vaccine (RIX4414) in Hong Kong children up to three years of age: A randomized, controlled trial

AbstractBackgroundA phase III, double-blind, randomized, controlled trial was conducted in Hong Kong to evaluate the efficacy, safety and immunogenicity of a human rotavirus vaccine, RIX4414 (Rotarix™) against severe rotavirus gastroenteritis in children up to three years of age.MethodsHealthy infants aged 6–12 weeks were enrolled between 08-December-2003 and 31-August-2005 and received two oral doses of either RIX4414 vaccine (N=1513) or placebo (N=1512) given 2 months apart. Vaccine efficacy was assessed from two weeks post-Dose 2 until the children were two and three years of age. Anti-rotavirus IgA seroconversion rate was calculated pre-vaccination and 1–2 months post-Dose 2 using ELISA (cut-off=20U/mL) for 100 infants. Safety was assessed until the children were two years of age; serious adverse events (SAEs) were recorded throughout the study period.ResultsIn children aged two and three years of life, vaccine efficacy against severe rotavirus gastroenteritis was 95.6% (95% CI: 73.1%–99.9%) and 96.1% (95% CI: 76.5%–99.9%), respectively. The seroconversion rate 1–2 months after the second dose of RIX4414 was 97.5% (95% CI: 86.8%–99.9%). At least one SAE was recorded in 439 and 477 infants who were administered RIX4414 and placebo, respectively (p-value=0.130). Six intussusception cases were reported (RIX4414=4; placebo=2) and none was assessed to be vaccine-related.ConclusionRIX4414 was efficacious, immunogenic and safe in the prevention of rotavirus gastroenteritis for at least two years post-vaccination in Hong Kong children

Sex-based differences in risk of ischaemic stroke or systemic embolism after BNT162b2 or CoronaVac COVID-19 vaccination in patients with atrial fibrillation: a self-controlled case series and nested case-control study

AIMS: Patients with atrial fibrillation (AF) have a higher risk of ischemic stroke or systemic embolism with a greater risk for female patients. This study aims to evaluate the risk of ischemic stroke or systemic embolism and bleeding following COVID-19 vaccination in patients with AF and the sex differences. METHODS AND RESULTS: Self-controlled case series (SCCS) analysis was conducted to evaluate the risk of ischemic stroke or systemic embolism and bleeding following BNT162b2 or CoronaVac in patients with AF, using the territory-wide electronic medical records from the Hospital Authority and vaccination records from the Department of Health in Hong Kong. Patients with a primary diagnosis of ischemic stroke or systemic embolism or bleeding in the inpatient setting between February 23, 2021 and March 31, 2022 were included. A nested case-control analysis was also conducted with each case randomly matched with ten controls according to sex, age, Charlson comorbidity index and date of hospital admission. Conditional Poisson regression was used in the SCCS analysis and conditional logistic regression was used in nested case-control analysis to assess the risks and all analyses were stratified by sex and type of vaccines. Among 51 158 patients with AF, we identified an increased risk of ischemic stroke or systemic embolism after the first dose of BNT162b2 in SCCS analysis during 0-13 days (incidence rate ratio 6.60[95% CI 1.51-28.77]) and 14-27 days (6.53[95% CI 1.31-32.51]), and nested case-control analysis during 0-13 days (adjusted odds ratio 6.21 [95% CI 1.14-33.91]) and 14-27 days (5.52 [95% CI 1.12-27.26]) only in female patients. The increased risk in female patients following the first dose of CoronaVac was only detected during 0-13 days (3.88 [95% CI 1.67-9.03]) in the nested case-control analysis. No increased risk of ischemic stroke or systemic embolism was identified in male patients and no increased risk of bleeding was detected in all patients with AF for both vaccines. An increased risk of ischemic stroke or systemic embolism after COVID-19 was also observed in both females (17.42 [95% CI 5.08-59.73]) and males (6.63 [95% CI 2.02-21.79]). CONCLUSIONS: The risk of ischemic stroke or systemic embolism after COVID-19 vaccination was only increased in female patients with AF. However, as the risk after COVID-19 was even higher, proactive uptake of COVID-19 vaccines is recommended to prevent the potential severe outcomes after infection

Relationship between mitral leaflets angles, left ventricular geometry and mitral deformation indices in patients with ischemic mitral regurgitation: imaging by echocardiography and cardiac magnetic resonance

Chronic ischemic mitral regurgitation (IMR) is associated with a markedly worse prognosis after myocardial infarction (MI).The study aimed to evaluate the relationship between anterior and posterior mitral leaflet angle (MLA) values, left ventricle remodeling and severity of ischaemic mitral regurgitation (IMR). Methods: Forty-two patients (age 63.5 ± 9.7 years, 36 men) with chronic IMR (regurgitant volume, RV > 20 ml; >6 months after MI) underwent transthoracic echocardiography (TTE) and cardiovascular magnetic resonance (CMR) imaging. Anterior and posterior MLA, determined by echocardiography, were correlated with indices of LV remodeling, mitral apparatus deformation and IMR severity by CMR. The anterior and posterior MLA was 25.41 ± 4.28 and 38.37 ± 8.89° (mean ± SD). In 5 patients (11.9%) the posterior MLA was ≥45°. There was a significant correlation between anterior MLA and RV (r = 0.74, P = 0.01). For patients with RV > 30 ml this correlation was stronger (r = 0.97, P = 0.005) and, in addition, there was a correlation between the RV and posterior MLA (r = 0.90, P = 0.037), between tenting area and posterior MLA (r = 0.90, P = 0.04), and between tenting area and anterior MLA (r = 0.82, P = 0.08). With regard to LV remodeling parameters, there was weaker but significant correlation between posterior MLA and LV end-diastolic volume index (r = 0.35, P = 0.031), LV end-systolic volume index (r = 0.37, P = 0.021), stroke volume (r = 0.35, P = 0.03), sphericity index (r = 0.33, P = 0.041). Anterior MLA correlated with wall motion score index (r = 0.41, P = 0.019). Besides, there was a correlation between posterior MLA and left atrial volume (r = 0.41, P = 0.012). Measurement of anterior and posterior MLA may play an important role in evaluating patients with IMR

Age- and sex-specific physical fitness reference and association with body mass index in Hong Kong Chinese schoolchildren

There is lacking a population-based study on the fitness level of Hong Kong schoolchildren, and it seems that increasing childhood obesity prevalence has shifted the classification of healthy fitness, with ‘underfit’ as normal. This cross-sectional territory study aimed to develop an age- and sex-specific physical fitness reference using a representative sample of children aged 6–17 and to determine the associations with body mass index in schoolchildren. The study analyzed Hong Kong School Physical Fitness Award Scheme data covering grade 1 to grade 12 students’ physical fitness and anthropometric measurements from 2017 to 2018. This reference was established without the impact due to COVID-19. Four aspects of physical fitness tests were measured using a standardized protocol, including (i) upper limb muscle strength, (ii) one-minute sit-up, (iii) sit-and-reach, and (iv) endurance run tests. The generalized additive model for location, scale, and shape was used to construct the reference charts. A Mann–Whitney U test was used to compare the mean differences in age, weight, and height, and a Pearson’s chi-square test was used to examine the distributions of sex groups. A Kruskal–Wallis test was used to compare the group differences in BMI status, followed by the Dunn test for pairwise comparisons. A 5% level of significance was regarded as statistically significant. Data of 119,693 students before the COVID-19 pandemic were included in the analysis. The association between physical fitness level and BMI status varied depending on the test used, and there were significant differences in fitness test scores among BMI groups. The mean test scores of the obese group were lower in most of the tests for both boys and girls, except for handgrip strength. The underweight group outperformed the obese group in push-ups, one-minute sit-ups, and endurance run tests, but not in handgrip strength. In conclusion, a sex- and age-specific physical fitness reference value for Hong Kong Chinese children aged 6 to 17 years old is established, and this study demonstrated a nonlinear relationship between BMI status and physical fitness. The reference will help to identify children with poor physical fitness to offer support and guidance on exercise training. It also serves as a baseline for assessing the impact of the COVID-19 pandemic on Hong Kong students’ physical fitness