Previous tuberculosis disease as a risk factor for chronic obstructive pulmonary disease:a cross-sectional analysis of multicountry, population-based studies

Background Risk factors for COPD in high-income settings are well understood; however, less attention has been paid to contributors of COPD in low-income and middle-income countries (LMICs) such as pulmonary tuberculosis. We sought to study the association between previous tuberculosis disease and COPD by using pooled population-based cross-sectional data in 13 geographically diverse, low-resource settings. Methods We pooled six cohorts in 13 different LMIC settings, 6 countries and 3 continents to study the relationship between self-reported previous tuberculosis disease and lung function outcomes including COPD (defined as a postbronchodilator forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) below the lower limit of normal). Multivariable regressions with random effects were used to examine the association between previous tuberculosis disease and lung function outcomes. Results We analysed data for 12 396 participants (median age 54.0 years, 51.5% male); 332 (2.7%) of the participants had previous tuberculosis disease. Overall prevalence of COPD was 8.8% (range 1.7%-15.5% across sites). COPD was four times more common among those with previous tuberculosis disease (25.7% vs 8.3% without previous tuberculosis disease,

Methodological correlation of finite element models to nanoindentation measurements on Si (100)

A viable approach to obtain mechanical properties such as Young\u2019s modulus and hardness, is testing on a nanoindentation device. Such an experimental procedure can, however, be time-consuming and expensive. Finite element analysis (FEA) can be employed to minimize the number of required measurements, i.e., to obtain numerically the load vs. indentation depth curves for varying input parameters, hence extracting the resulting elasto-plastic material properties. A methodological approach is used in this work to correlate the responses obtained via FEA to nanoindentation experimental data. A (100)-oriented single crystal silicon wafer is used as a testing sample. Numerical simulations are performed by employing a bilinear elasto-plastic material model. A sensitivity analysis of the characteristic parameters of the material model is then conducted on the numerically obtained load vs. displacement curves. The proposed methodology enables replicating the experimental curves with estimated errors lower than 1 % and 15 % for Young\u2019s modulus and hardness, respectively. The performed analyses allow establishing also that, when evaluating numerically hardness, the tip radius and shape significantly affect the accuracy of the results, especially for lower indentation depths