The challenges of containing SARS-CoV-2 via test-trace-and-isolate

Without a cure, vaccine, or proven long-term immunity against SARS-CoV-2, test-trace-and-isolate (TTI) strategies present a promising tool to contain the viral spread. For any TTI strategy, however, a major challenge arises from pre- and asymptomatic transmission as well as TTI-avoiders, which contribute to hidden, unnoticed infection chains. In our semi-analytical model, we identified two distinct tipping points between controlled and uncontrolled spreading: one, at which the behavior-driven reproduction number of the hidden infections becomes too large to be compensated by the available TTI capabilities, and one at which the number of new infections starts to exceed the tracing capacity, causing a self-accelerating spread. We investigated how these tipping points depend on realistic limitations like limited cooperativity, missing contacts, and imperfect isolation, finding that TTI is likely not sufficient to contain the natural spread of SARS-CoV-2. Therefore, complementary measures like reduced physical contacts and improved hygiene probably remain necessary

Multiscale modeling of a free-radical emulsion polymerization process: Numerical approximation by the Finite Element Method

A multiscale modeling description of free-radical polymerization processes is presented. The polymerization process is described at the macroscale by coupling the Fokker-Planck Equation (FPE) for the particle size distribution (PSD) prediction at the mesoscale with a kinetic Monte Carlo (kMC) simulation at the microscale. The finite element method is adopted to solve the mesoscopic scale to capture the nonlinear evolution of the PSD, successfully facing challenges related to accuracy and computational cost in the FPE numerical solution. Additionally, the proposed model captures the evolution of the average number of free-radicals and secondary nucleation rate at the microscopic level. The control of the secondary nucleation rate is in fact critical to satisfactorily obtain high quality structured polymer particles. Finally, a closed-form model is developed at the microscopic scale to handle the curse of dimensionality. Simulations to evaluate the capabilities of the proposed numerical scheme and sensitivity analyses with respect to the system inputs and uncertainties in the initial condition of the PSD are performed. (C) 2020 Elsevier Ltd. All rights reserved

PI/PID controller stabilizing sets of uncertain nonlinear systems: an efficient surrogate model-based approach

Closed forms of stabilizing sets are generally only available for linearized systems. An innovative numerical strategy to estimate stabilizing sets of PI or PID controllers tackling (uncertain) nonlinear systems is proposed. The stability of the closed-loop system is characterized by the sign of the largest Lyapunov exponent (LLE). In this framework, the bottleneck is the computational cost associated with the solution of the system, particularly including uncertainties. To overcome this issue, an adaptive surrogate algorithm, the Monte Carlo intersite Voronoi (MiVor) scheme, is adopted to pertinently explore the domain of the controller parameters and classify it into stable/unstable regions from a low number of nonlinear estimations. The result of the random analysis is a stochastic set providing probability information regarding the capabilities of PI or PID controllers to stabilize the nonlinear system and the risk of instabilities. The minimum of the LLE is proposed as tuning rule of the controller parameters. It is expected that using a tuning rule like this results in PID controllers producing the highest closed-loop convergence rate, thus being robust against model parametric uncertainties and capable of avoiding large fluctuating behavior. The capabilities of the innovative approach are demonstrated by estimating robust stabilizing sets for the blood glucose regulation problem in type 1 diabetes patients

Anisotropic multi-element polynomial chaos expansion for high-dimensional non-linear structural problems

International audienc

Preservación de técnicas artesanales para el diseño de textiles y productos de la fbra de agave: juntos hacia un desarrollo local sustentable IV

El proyecto Preservación de Técnicas Artesanales para el Diseño de Textiles y Productos de la Fibra de Agave: Juntos Hacia un Desarrollo Local Sustentable IV, pretende ofrecer a las comunidades artesanales y pequeños productores en el pueblo de Tequila herramientas de organización, al fomentar capacidades autogestivas para que puedan caminar en un futuro hacia un modelo de desarrollo social, creativo y económico local alternativo. El proyecto se centra en la recuperación de técnicas y el manejo de la fibra y otros materiales derivados del agave, lo cual proporciona la posibilidad de que los artesanos entren a un desarrollo de productos en un ciclo sustentable. En este periodo se trabajó en el proyecto arquitectónico y en el desarrollo gráfico de marca para una comercializadora social, que se piensa como el lugar donde los artesanos y pequeños productores podrán comercializar sus productos.Fundación José Cuerv

Rivaroxaban with or without aspirin in stable cardiovascular disease

BACKGROUND: We evaluated whether rivaroxaban alone or in combination with aspirin would be more effective than aspirin alone for secondary cardiovascular prevention. METHODS: In this double-blind trial, we randomly assigned 27,395 participants with stable atherosclerotic vascular disease to receive rivaroxaban (2.5 mg twice daily) plus aspirin (100 mg once daily), rivaroxaban (5 mg twice daily), or aspirin (100 mg once daily). The primary outcome was a composite of cardiovascular death, stroke, or myocardial infarction. The study was stopped for superiority of the rivaroxaban-plus-aspirin group after a mean follow-up of 23 months. RESULTS: The primary outcome occurred in fewer patients in the rivaroxaban-plus-aspirin group than in the aspirin-alone group (379 patients [4.1%] vs. 496 patients [5.4%]; hazard ratio, 0.76; 95% confidence interval [CI], 0.66 to 0.86; P<0.001; z=−4.126), but major bleeding events occurred in more patients in the rivaroxaban-plus-aspirin group (288 patients [3.1%] vs. 170 patients [1.9%]; hazard ratio, 1.70; 95% CI, 1.40 to 2.05; P<0.001). There was no significant difference in intracranial or fatal bleeding between these two groups. There were 313 deaths (3.4%) in the rivaroxaban-plus-aspirin group as compared with 378 (4.1%) in the aspirin-alone group (hazard ratio, 0.82; 95% CI, 0.71 to 0.96; P=0.01; threshold P value for significance, 0.0025). The primary outcome did not occur in significantly fewer patients in the rivaroxaban-alone group than in the aspirin-alone group, but major bleeding events occurred in more patients in the rivaroxaban-alone group. CONCLUSIONS: Among patients with stable atherosclerotic vascular disease, those assigned to rivaroxaban (2.5 mg twice daily) plus aspirin had better cardiovascular outcomes and more major bleeding events than those assigned to aspirin alone. Rivaroxaban (5 mg twice daily) alone did not result in better cardiovascular outcomes than aspirin alone and resulted in more major bleeding events