A geometrically-exact Finite Element Method for micropolar continua with finite deformations

Micropolar theory is a weakly non-local higher-order continuum theory based on the inclusion of independent (micro-)rotational degrees of freedom. Subsequent introduction of couple-stresses and an internal length scale mean the micropolar continuum is therefore capable of modelling size effects. This paper proposes a non-linear Finite Element Method based on the spatial micropolar equilibrium equations, but using the classical linear micropolar constitutive laws defined in the reference configuration. The method is verified rigorously with the Method of Manufactured Solutions, and quadratic Newton-Raphson convergence of the minimised residuals is demonstrated

Effect of Aspect Ratio on the Low-Speed Lateral Control Characteristics of Untapered Low-Aspect-Ratio Wings Equipped with Flap and with Retractable Ailerons

A low-speed wind-tunnel investigation was made to determine the lateral control characteristics of a series of untapered low-aspect-ratio wings. Sealed flap ailerons of various spans and spanwise locations were investigated on unswept wings of aspect ratios 1.13, 1.13, 4.13, and 6.13; and various projections of 0.60-semispan retractable ailerons were investigated on the unsweptback wings of aspect ratios 1.13, 2.13, and 4.13 and on a 45 degree sweptback wing. The retractable ailerons investigated on the unswept wings spanned the outboard stations of each wing; whereas the plain and stepped retractable ailerons investigated on the sweptback wing were located at various spanwise stations. Design charts based on experimental results are presented for estimating the flap aileron effectiveness for low-aspect-ratio, untapered, unswept

Patient and provider determinants of nephrology referral in older adults with severe chronic kidney disease: a survey of provider decision making

<p>Abstract</p> <p>Background</p> <p>Although chronic kidney disease (CKD) disproportionately affects older adults, they are less likely to be referred to a nephrologist. Factors that influence the referral decisions of primary care providers (PCPs) specifically for older CKD patients have been incompletely described. Patient factors such as dementia, functional disability, and co-morbidity may complicate the decision to refer an older adult. This study evaluated the role of patient and PCP factors in the referral decisions for older adults with stage 4 CKD.</p> <p>Methods</p> <p>We administered a two-part survey to study the decisions of practicing PCPs. First, using a blocked factorial design, vignettes systematically varied 6 patient characteristics: age, race, gender, co-morbidity, functional status, and cognitive status. CKD severity, patient preferences, and degree of anemia were held constant. Second, covariates from a standard questionnaire included PCP estimates of life expectancy, demographics, reaction to clinical uncertainty, and risk aversion. The main outcome was the decision to refer to the nephrologist. Random effects logistic regression models tested independent associations of predictor variables with the referral decision.</p> <p>Results</p> <p>More than half (62.5%) of all PCP decisions (n = 680) were to refer to a nephrologist. Vignette-based factors that independently decreased referral included older patient age (OR = 0.27; 95% CI, 0.15 to 0.48) and having moderate dementia (OR = 0.14; 95%CI, 0.07 to 0.25). There were no associations between co-morbidity or impaired functional activity with the referral decision. Survey-based PCP factors that significantly increased the referral likelihood include female gender (OR = 7.75; 95%CI, 2.07 to 28.93), non-white race (OR = 30.29; 95%CI, 1.30 to 703.73), those who expect nephrologists to discuss goals of care (OR = 53.13; 95%CI, 2.42 to 1168.00), those with higher levels of anxiety about uncertainty (OR = 1.28; 95%CI, 1.04 to 1.57), and those with greater risk aversion (OR = 3.39; 95%CI, 1.02 to 11.24).</p> <p>Conclusions</p> <p>In this decision making study using hypothetical clinical vignettes, we found that the PCP decision to refer older patients with severe CKD to a nephrologist reflects a complex interplay between patient and provider factors. Age, dementia, and several provider characteristics weighed more heavily than co-morbidity and functional status in PCP referral decisions. These results suggest that practice guidelines should develop a more nuanced approach to the referral of older adults with CKD.</p