Optimization of Patterned Surfaces for Improved Superhydrophobicity Through Cost-Effective Large-Scale Computations

The growing need for creating surfaces with specific wetting properties, such as superhyrdophobic behavior, asks for novel methods for their efficient design. In this work, a fast computational method for the evaluation of patterned superhyrdophobic surfaces is introduced. The hydrophobicity of a surface is quantified in energy terms through an objective function. The increased computational cost led to the parallelization of the method with the Message Passing Interface (MPI) communication protocol that enables calculations on distributed memory systems allowing for parametric investigations at acceptable time frames. The method is demonstrated for a surface consisting of an array of pillars with inverted conical (frustum) geometry. The parallel speedup achieved allows for low cost parametric investigations on the effect of the fine features (curvature and slopes) of the pillars on the superhydophobicity of the surface and consequently for the optimization of superhyrdophobic surfaces.Comment: 18 pages, 18 figure

The normal field instability under side-wall effects: comparison of experiments and computations

We consider a single spike of ferrofluid, arising in a small cylindrical container, when a vertically oriented magnetic field is applied. The height of the spike as well as the surface topography is measured experimentally by two different technologies and calculated numerically using the finite element method. As a consequence of the finite size of the container, the numerics uncovers an imperfect bifurcation to a single spike solution, which is forward. This is in contrast to the standard transcritical bifurcation to hexagons, common for rotational symmetric systems with broken up-down symmetry. The numerical findings are corroborated in the experiments. The small hysteresis observed is explained in terms of a hysteretic wetting of the side wall.Comment: accepted to New Journal of Physic

Comparative effectiveness, safety, and costs of rivaroxaban and warfarin among morbidly obese patients with atrial fibrillation.

BACKGROUND: There are limited data regarding clinical outcomes and healthcare resource utilization of direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) who are morbidly obese (body mass index \u3e40 kg/m METHODS: Using data from 2 US healthcare claims databases, we identified patients initiating rivaroxaban or warfarin who had ≥1 medical claim with an AF diagnosis, a diagnostic code for morbid obesity (ICD-9: 278.01, V85.4%; ICD-10: E66.01%, E66.2%, Z68.4%), and a minimum continuous enrollment of 12 months before and 3 months after treatment initiation. Patients were excluded if they had mitral stenosis, a mechanical heart valve procedure, an organ/tissue transplant, or an oral anticoagulant prescription prior to the index date. Rivaroxaban and warfarin patients were 1:1 propensity score matched. Conditional logistic regression was used to compare ischemic stroke/systemic embolism and major bleeding risk. Generalized linear models were used to compare healthcare resource utilization and costs. RESULTS: A total of 3563 matched pairs of morbidly obese AF patients treated with rivaroxaban or warfarin were identified. The majority (81.4%) of patients in the rivaroxaban cohort were receiving the 20 mg dose. The rivaroxaban and warfarin cohorts were well balanced after propensity score matching. The risks of ischemic stroke/systemic embolism and major bleeding were similar for rivaroxaban and warfarin users (stroke/systemic embolism: 1.5% vs 1.7%; odds ratio [OR]: 0.88; 95% confidence interval [CI]: 0.60, 1.28; P = .5028; major bleeding: 2.2% vs 2.7%; OR: 0.80; 95% CI: 0.59, 1.08; P = .1447). Total healthcare costs including medication costs per patient per year (PPPY) were significantly lower with rivaroxaban versus warfarin ($48,552 vs$52,418; P = .0025), which was primarily driven by lower hospitalization rate (50.2% vs 54.1%; P = .0008), shorter length of stay (7.5 vs 9.1 days; P = .0010), and less outpatient service utilization (86 vs 115 visits PPPY; P \u3c .0001). CONCLUSIONS: Morbidly obese AF patients treated with rivaroxaban had comparable risk of ischemic stroke/systemic embolism and major bleeding as those treated with warfarin, but lower healthcare resource utilization and costs

Rivaroxaban versus warfarin treatment among morbidly obese patients with venous thromboembolism: Comparative effectiveness, safety, and costs.

INTRODUCTION: Limited data exist on direct-acting oral anticoagulants in morbidly obese patients with venous thromboembolism (VTE). We compared clinical and health/economic outcomes with rivaroxaban versus warfarin for VTE treatment in morbidly obese patients. MATERIALS AND METHODS: This retrospective 1:1 propensity score matched cohort study analyzed data from 2 US claims databases. VTE patients initiating rivaroxaban or warfarin were identified who had diagnosis codes for morbid obesity (ICD-9:278.01,V85.4; ICD-10:E66.01,E66.2,Z68.4) 12 months pre- or 3 months post-initiation and followed ≥3 months. Intent-to-treat (ITT) and on-treatment (OT) analyses were conducted using conditional logistic regression and generalized linear models to compare recurrent VTE and major bleeding risks, healthcare resource utilization (HRU), and per patient per year (PPPY) costs. RESULTS: In total, 2890 matched pairs of morbidly obese VTE patients initiating rivaroxaban or warfarin were identified. Risks of recurrent VTE (ITT: OR: 0.99; 95% CI: 0.85-1.14) and major bleeding (OT: OR: 0.75; 95% CI: 0.47-1.19) were similar for cohorts. Anti-Factor Xa laboratory measurement was performed on CONCLUSIONS: Morbidly obese VTE patients receiving rivaroxaban had similar risks of recurrent VTE and major bleeding versus warfarin. Rivaroxaban treatment yielded significantly less HRU and total medical costs, with similar total healthcare costs between groups