Crack Group Effect Analysis of the Stress-Release Boot of Solid Rocket Motor Based on Numerical Simulation

Due to the complex process of the insulation layer patch in solid rocket motor (SRM), only manual patch could be used. Sometimes weak bonding or debonding in each joint surface was inevitable. This study is aimed at determining the crack group effect of insulation and interfacial debonded crack in the wide-temperature SRM. The crack group appeared in the front area of the ahead stress-release boot and was induced by low temperature, axial overload, or interface bonding failure. Based on the viscoelastic finite element method, singular crack elements and singular interfacial crack elements at the tips of crack group were established to calculate J -integral. Varying according to the length and position of cracks, the J -integral of crack tips was, respectively, calculated to prejudge their stability and the crack group effect. The results showed that collinear crack group appeared in the front stress-release boot layer, and the crack group had a certain shielding effect on the main crack when the SRM was launched at low temperature. When noncollinear crack group appeared in the front stress-release boot layer, the crack group effect changed with the length of the main crack. The crack group first had a shielding effect on the main crack and then had a strong strengthening effect. The experimental test of the simulated specimen revealed that numerical simulation results matched the experimental test results.

Methods Used to Evaluate the Immediate Effects of Airway Clearance Techniques in Adults with Cystic Fibrosis: A Systematic Review and Meta-Analysis

This review reports on methods used to evaluate airway clearance techniques (ACT) in adults with CF and examined data for evidence of any effect. Sixty-eight studies described ACT in adequate detail and were included in this review. Frequently reported outcomes were sputum expectoration (72%) and spirometric lung function (60%). Compared with cough alone, following any ACT, there was a trend for greater sputum wet weight, however FEV1 was not different. The mean (95% CI) within-group effect for sputum wet weight following any ACT was 12.43 g (9.28 to 15.58) (n = 30 studies) and for FEV1 was 0.03 L (−0.17 to 0.24) (n = 14 studies). Meta-regression demonstrated that, when compared with cough alone, greater sputum wet weight was reported in groups that received additional ACT by between 2.45 and 3.94 g (F3,66 = 2.97, p = 0.04). These data suggest the addition of ACT to cough alone may optimise sputum clearance; however, FEV1 lacked sensitivity to detect this change. Importantly, this review highlights the lack of appropriate measures to assess ACT efficacy.

Investigation of Health Science Students' Knowledge Regarding Healthy Lifestyle Promotion During the Spread of COVID-19 Pandemic: A Randomized Controlled Trial

Background: Health sciences students as future health care providers, can play a valuable role in protecting societies against the spread of COVID-19 through health promotion and lifestyle modification education. Therefore, proper education of these students is essential.Objective: This study sought to assess and measure the change of knowledge of health sciences students regarding healthy lifestyle promotion strategies during the spread of the Covid-19 pandemic, after participation in different types of online and social media educational programs.Methods: In order to serve the purpose of the study, a methodological research design was first used to ensure the validation of the developed scale; the COVID-19 Healthy Lifestyle Promotion Scale (COVID-19 HLPS). The study utilized a four-arm randomized control research design in which the participants were randomly assigned into one of four groups, (1) control group (placebo intervention), (2) brochure group, who received brochures relevant to healthy lifestyle promotion, (3) Instagram group, who received similar information but through Instagram posts, and (4) online interactive educational workshop group, who also received similar information through an online interactive educational workshop.Results: In total, 155 participants participated in the online and social media intervention programs. There was a significant improvement in the intervention groups in the total knowledge subscale of the healthy promotion strategies compared with the control group (p < 0.001). Overall, the workshop group was the most effective group (effect size = 1.54) followed by the Instagram group (effect size = 0.99) and then the brochure group (effect size = 0.91).Conclusions: In order to meet the challenges posed by this pandemic, the use of such online and social media interventions is essential and may be the key for health promotion during this pandemic. Health science students, as future health care professionals, can play a fundamental role during the COVID-19 pandemic in disseminating knowledge relevant to healthy lifestyle to their families and communities thus promoting healthy living and behavioral changes. We propose the development of research initiatives at both national and international levels targeting changes within health science curricula that can meet potential challenges of future pandemics, leading to advancement of health care services globally.

Testing the Efficacy of Attitudinal Inoculation Videos to Enhance COVID-19 Vaccine Acceptance: A Quasi-Experimental Intervention Trial (Preprint)

BACKGROUND Over the course of the COVID-19 pandemic, a variety of COVID-19 related misinformation has spread and been amplified online. The spread of misinformation can influence COVID-19 beliefs and protective actions including vaccine hesitancy. Belief in vaccine misinformation is associated with lower vaccination rates and higher vaccine resistance. Attitudinal inoculation is a preventative approach to combating misinformation and disinformation which leverages the power of narrative, rhetoric, values, and emotion. OBJECTIVE This study seeks to test inoculation messages in the form of short video messages to promote resistance against persuasion by COVID-19 vaccine misinformation. METHODS We designed a series of 30-second inoculation videos and conducted a quasi-experimental study to test the use of attitudinal inoculation in a population of individuals who were unvaccinated. The three intervention videos were distinguished by their script design- with Intervention Video 1 focusing on narrative/rhetorical (“Narrative”) presentation of information, Intervention Video 2 focusing on delivering a fact-based information (“Fact”), and Intervention Video 3 using a hybrid design (“Hybrid”). Analysis of covariance (ANCOVA) models were used to compare the main effect of intervention group on the three outcome variables: ability to recognize misinformation tactics (“Recognize”, willingness to share misinformation (“Share”), and willingness to take the COVID-19 vaccine (“Willingness”). RESULTS There were significant effects across all three outcome variables comparing inoculation intervention groups to controls. For the Recognize outcome, the ability to recognize rhetorical strategies, there was a significant intervention group effect (F(3,1929)=8.5, p<0.0001). For the Share outcome, support for sharing the mis-disinformation, the intervention group main effect was statistically significant (F(3,1928)=3.4, p=0.0168). For the Willingness outcome, there was a significant intervention group effect; intervention groups were more willing to get the COVID-19 vaccine compared to controls (F(3,1929)=4.1, p=0.0064). CONCLUSIONS Across all intervention groups, inoculated individuals showed greater resistance to misinformation than their non-inoculated counterparts. Relative to those who were not inoculated, inoculated participants showed significantly greater ability to recognize and identify rhetorical strategies used in misinformation, were less likely to share false information, and had greater willingness to get the COVID-19 vaccine. Attitudinal inoculation delivered through short video messages should be tested in public health messaging campaigns to counter mis-disinformation

Effects of a WeChat-based individualized post-discharge rehabilitation program on patients with lumbar fusion surgery

BACKGROUND: Exercise training after lumbar fusion surgery (LFS) is important for regaining the strength in the spinal muscles, pain management, and minimizing dysfunction. It may be prudent to evaluate technologies such as web-based chat and social media apps for increasing the efficacy of post-surgery interventions in LFS patients. OBJECTIVE: To explore the effectiveness of a WeChat-based individualized post-discharge rehabilitation program in patients with LFS. METHODS: Seventy-two eligible discharged LFS patients were enrolled from October 2018 to February 2019. The experimental group (36 cases) received a 10-week WeChat-based individualized rehabilitation program, while the control group (36 cases) received routine follow-up guidance. The outcomes were measured using the Exercise Compliance Questionnaire, Numerical Rating Scale, Oswestry Disability Index and Chinese version of the self-efficacy for exercise scale. RESULTS: The analysis using generalized estimation equations method shows significant differences in the interaction effect of group*time in exercise compliance (Wald c2= 7.459, P< 0.05), group effect in pain (Wald c2= 5.811, P< 0.05) and self-efficacy (Wald c2= 16.383, P< 0.05). However, there was no significant difference between the experimental and control groups in the group effect in dysfunction improvement (Wald c2= 2.289, P> 0.05). CONCLUSIONS: The WeChat-based rehabilitation intervention can improve exercise compliance and self-efficacy, and help achieve greater pain relief compared to the routine intervention. However, the WeChat-based intervention did not offer better improvement in the self-dysfunction in the post-discharge LFS patients.