We propose a fully mixed virtual element method (VEM) for the numerical approximation of the coupling between linear poroelasticity equations with strong symmetry of total poroelastic stress (using the Hellinger-Reissner (HR) principle) and stress-altered solute diffusion (where diffusive flux depends on the poroelastic stress and nonlinearly on the concentration gradient). Because of the nonlinear coupling, the function spaces associated with the nonlinear diffusion sub-problem are of Banach type. To handle this structure, the solvability of both the continuous and discrete problems is established through a decoupled fixed-point strategy. The linear poroelasticity component is analysed using the theory for perturbed saddle-point problems, whereas the analysis of the nonlinear diffusion problem relies on the classical Minty-Browder theorem for monotone global operators. The existence of solutions for the fully coupled system is rigorously proven via Schauder's fixed-point theorem. Additionally, we establish rigorous a priori error estimates for the discrete scheme, successfully handling the strongly cross-coupled nonlinearities. These findings are supported by computational evidence, demonstrating that the formulation asymptotically recovers optimal convergence rates in practice. As a key contribution, both the numerical scheme and its underlying analysis prove to be robust with respect to the poromechanical parameters. Finally, several numerical examples are presented to illustrate the properties and applicability of the proposed scheme in the study of solute transport in the context of brain multiphysics.
Distribution utilities have started using shunt capacitors installed in low voltage (LV) systems to provide reactive power compensation to the circuit at a lower cost. Such installation, however, creates risk of harmonic resonances in the LV circuit. This raises concern for engineers responsible for LV system planning as they do not normally perform resonance assessment in LV systems. Thus, it is important to develop a tool that assists these engineers in quickly identifying if a capacitor connection presents risk of resonance. This paper proposes three charts to map parameter combinations that cause problematic resonance in the circuit according to three different scenarios of data availability and study goals. If the LV system is out of problematic regions of the chart, the capacitor can be safely installed without running any simulation study. Otherwise, more detailed investigations must be performed. This is an attractive approach for quick first-screening analyses as the charts can be obtained through simple equations and use only information that is readily available in practice to engineers. They also enable LV systems to be assessed comparatively, so that the safest capacitor location within a pre-defined region can be identified. Single-phase distributed energy resources connected on LV systems are evaluated and the proposed charts are proven to be effective even in their presence. The charts are validated in more than 36,000 real Brazilian LV systems.
Research on self-regulation has predominantly been focused on positive framed constructs (e.g.: doing something). In contrast, negation self-regulation (not doing something) and its association with behavior and habit remains widely under-researched. This study aimed to examine the direction of: (1) longitudinal associations between negation self-regulation variables (negative formulations of intentions-plans-action control); (2) longitudinal associations between negation action control and snacking behavior and; (3) longitudinal associations between snacking behavior and habit. This was done by means of a three-wave panel study conducted with Costa Rican high school students (n = 203, Mage = 15.39 (SD = 1.43)). Data were analyzed using cross-lagged panel modeling. Findings were different to those expected for positive self-regulation variables. It was found that: (1) negation action control was associated to subsequent negation plans, and negation plans were associated to subsequent negation intentions; (2) negation action control was not longitudinally related to snacking behavior and; (3) snacking behavior and habit were longitudinally and bidirectionally associated. Theoretical accounts and implications are discussed.
An environmental risk assessment of pharmaceuticals was conducted in surface waters from a tropical agricultural region in Costa Rica to describe their potential effects in rural ecosystems. The study collected 58 surface water samples from 22 sampling points in an intensive pineapple cultivation area in the Northern Region of the country and analyzed pharmaceuticals using a multiresidue method by Ultra-High Performance Liquid Chromatography (UHPLC) coupled to a triple quadrupole mass spectrometer. Environmental risks were assessed using chronic (Hazard Quotient, HQ), acute (Toxic Units, TU), and antibiotic resistance selection (HQRes) risk assessments. Monitoring revealed contamination with 15 different pharmaceuticals, including a predominance of antibiotics and caffeine, which showed the highest concentrations (max 17.5 µg/L). The risk assessment identified that 10 of the 15 detected pharmaceuticals posed a moderate to high chronic risk to aquatic life; specifically, sulfathiazole, clarithromycin, caffeine, and ofloxacin were categorized as high-risk compounds (HQ > 1). Furthermore, ciprofloxacin and clarithromycin posed a high risk for the selection of antimicrobial resistance. Although acute risk was seldom described, it was mainly driven by pharmaceutical mixtures, with clindamycin identified as a high-risk compound for fish in one sample. The findings emphasize the critical need for surveillance and targeted mitigation strategies to address emerging threats, particularly antibiotics, in tropical agricultural landscapes.
