On the development of a nonlinear time-domain numerical method for describing vortex-induced vibration and wake interference of two cylinders using experimental results

A nonlinear mathematical model is developed in the time domain to simulate the behaviour of two identical flexibly mounted cylinders in tandem while undergoing vortex-induced vibration (VIV). Subsequently, the model is validated and modified against experimental results. Placing an array of bluff bodies in proximity frequently happens in different engineering fields. Chimney stacks, power transmission lines and oil production risers are few engineering structures that may be impacted by VIV. The coinciding of the vibration frequency with the structure natural frequency could have destructive consequences. The main objective of this study is to provide a symplectic and reliable model capable of capturing the wake interference phenomenon. This study shows the influence of the leading cylinder on the trailing body and attempts to capture the change in added mass and damping coefficients due to the upstream wake. The model is using two coupled equations to simulate the structural response and hydrodynamic force in each of cross-flow and stream-wise directions. Thus, four equations describe the fluid-structure interaction of each cylinder. A Duffing equation describes the structural motion, and the van der Pol wake oscillator defines the hydrodynamic force. The system of equations is solved analytically. Two modification terms are added to the excitation side of the Duffing equation to adjust the hydrodynamic force and incorporate the effect of upstream wake on the trailing cylinder. Both terms are functions of upstream shedding frequency (Strouhal number). Additionally, the added mass modification coefficient is a function of structural acceleration and the damping modification coefficient is a function of velocity. The modification coefficients values are determined by curve fitting to the difference between upstream and downstream wake forces, obtained from experiments. The damping modification coefficient is determined by optimizing the model against the same set of experiments. Values of the coefficients at seven different spacings are used to define a universal function of spacing for each modification coefficient so that they can be obtained for any given distance between two cylinders. The model is capable of capturing lock-in range and maximum amplitude

Global, regional, and national incidence of six major immune-mediated inflammatory diseases: findings from the global burden of disease study 2019

Background The causes for immune-mediated inflammatory diseases (IMIDs) are diverse and the incidence trends of IMIDs from specific causes are rarely studied. The study aims to investigate the pattern and trend of IMIDs from 1990 to 2019. Methods We collected detailed information on six major causes of IMIDs, including asthma, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, psoriasis, and atopic dermatitis, between 1990 and 2019, derived from the Global Burden of Disease study in 2019. The average annual percent change (AAPC) in number of incidents and age standardized incidence rate (ASR) on IMIDs, by sex, age, region, and causes, were calculated to quantify the temporal trends. Findings In 2019, rheumatoid arthritis, atopic dermatitis, asthma, multiple sclerosis, psoriasis, inflammatory bowel disease accounted 1.59%, 36.17%, 54.71%, 0.09%, 6.84%, 0.60% of overall new IMIDs cases, respectively. The ASR of IMIDs showed substantial regional and global variation with the highest in High SDI region, High-income North America, and United States of America. Throughout human lifespan, the age distribution of incident cases from six IMIDs was quite different. Globally, incident cases of IMIDs increased with an AAPC of 0.68 and the ASR decreased with an AAPC of −0.34 from 1990 to 2019. The incident cases increased across six IMIDs, the ASR of rheumatoid arthritis increased (0.21, 95% CI 0.18, 0.25), while the ASR of asthma (AAPC = −0.41), inflammatory bowel disease (AAPC = −0.72), multiple sclerosis (AAPC = −0.26), psoriasis (AAPC = −0.77), and atopic dermatitis (AAPC = −0.15) decreased. The ASR of overall and six individual IMID increased with SDI at regional and global level. Countries with higher ASR in 1990 experienced a more rapid decrease in ASR. Interpretation The incidence patterns of IMIDs varied considerably across the world. Innovative prevention and integrative management strategy are urgently needed to mitigate the increasing ASR of rheumatoid arthritis and upsurging new cases of other five IMIDs, respectively. Funding The Global Burden of Disease Study is funded by the Bill and Melinda Gates Foundation. The project funded by Scientific Research Fund of Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital (2022QN38)

Cardiovascular outcomes in patients with intraventricular conduction blocks: A sixteen-year follow-up in a state-wide database

Background: To assess the adverse clinical effects of left anterior hemiblock alone or in combination with right bundle branch block and of complete left bundle branch block in comparison with isolated right bundle branch block and the relationship of these effects with altered mechanoelectric factors resulting in left ventricular dysfunction. Methods: In a 16-year follow-up study using a statewide database, we studied the occurrence of mortal and morbid cardiovascular (CV) events among patients without apparent ischemic heart disease who had left anterior hemiblock (LAHB, n=4273, right bundle branch block (RBBB) with LAHB (BFBB, n=1857) and left bundle branch block (LBBB, n=9484 compared to isolated RBBB (n=25288). Results: After adjustment for demographics, co-morbidities and insurance, LAHB was associated with a significant excess risk of all-cause death (HR 1.134, 95% CI 1.061-1.213, p=0.0002) and CV death (HR 1.329, 95% CI 1.174-1.501, p<0.0001). BFBB was associated with excess HF (HR 1.190, 95% CI 1.048-1.351, p<0.0071), all-cause death (HR 1.440, 95% CI 1.045-1.252, p=0.0036) and CV death (HR 1.210, 95% CI 1.020-1.436, p<0.0001). LBBB was associated with an excess risk of MR (HR 1.307, 95% CI 1.116-1.530, p<0.0009), HF 1.177, 95% CI1.097-1.263, p<0.0001) and CV death (HR 1.220, 95% CI 1.106-1.345, p<0.0001). Conclusions: In patients without apparent ischemic heart disease, the presence of LAHB alone or in combination with RBBB imparts increased risk of CV and all-cause death compared to isolated RBBB. BFBB is also associated with an increased risk of HF

The dual role of the extracellular matrix in synaptic plasticity and homeostasis

Recent studies have deepened our understanding of multiple mechanisms by which extracellular matrix (ECM) molecules regulate various aspects of synaptic plasticity and have strengthened a link between the ECM and learning and memory. New findings also support the view that the ECM is important for homeostatic processes, such as scaling of synaptic responses, metaplasticity and stabilization of synaptic connectivity. Activity-dependent modification of the ECM affects the formation of dendritic filopodia and the growth of dendritic spines. Thus, the ECM has a dual role as a promoter of structural and functional plasticity and as a degradable stabilizer of neural microcircuits. Both of these aspects are likely to be important for mental health