Open-source high-performance software packages for direct and inverse solving of horizontal capillary flow

This work introduces Fronts, a set of open-source numerical software packages for nonlinear horizontal capillary-driven flow problems in unsaturated porous media governed by the Richards equation. The software uses the Boltzmann transformation to solve such problems in semi-infinite domains. The scheme adopted by Fronts allows it to be faster and easier to use than other tools, and provide continuous functions for all involved fields. The software is capable of solving problems that appear in hydrology, but also in other particular domains of interest such as paper-based microfluidics. As the first known open-source implementation to adopt this approach, Fronts has been validated against analytical solutions as well as existing software achieving remarkable results in terms of computational costs and numerical precision, and is meant to aid the study and modeling of capillary flow. Fronts can be freely downloaded and installed, and offers a friendly environment for new users with its complete documentation and tutorial cases.Cited as: Gerlero, G. S., Berli, C. L. A., Kler, P. A. Open-source high-performance software packages for direct and inverse solving of horizontal capillary flow. Capillarity, 2023, 6(2): 31-40. https://doi.org/10.46690/capi.2023.02.0

Incremento de la eficiencia de los análisis de flujo lateral a través de campos eléctricos

Los análisis de flujo lateral (AFL) representan un grupo de dispositivos portables y autónomos para la detección rápida y sencilla de diversos indicadores bioquímicos de agentes patógenos y enfermedades. Además de las aplicaciones en salud, el uso de los AFL se ha extiendido al control ambiental, fitosanitario y bromatológico, entre otros campos requiriendo de la tecnología límites de detección muy ambiciosos. Recientemente, se ha demostrado que los límites de detección de los AFL pueden incrementarse al menos dos órdenes de magnitud, si se combinan con la aplicación de campos eléctricos para el transporte electroforético de especies. Es sabido que el desarrollo de dispositivos de AFL implica importantes esfuerzos experimentales dada la necesidad de explorar diseños, caracterizar los materiales utilizados y controlar los parámetros cinéticos de las reacciones. Si a esto sumamos la aplicación de campos eléctricos a soluciones de electrolitos con conductividades eléctricas heterogéneas, el escenario para el diseño empírico se vuelve demasiado complejo. De esta manera, contar con herramientas que permitan reducir los costos y tiempos de experimentación resulta clave para la implementación efectiva de esta tecnología. Para ello el desarrollo de prototipos numéricos que permitan simular eficientemente nuevos diseños de AFL sometidos a campos eléctricos resulta de gran utilidad tecnológica y científica. En este trabajo se presenta la implementación de un prototipo numérico de un AFL sometido a campos eléctricos. El modelo consiste en la solución acoplada de: (i) un modelo fluidodinámico de imbibición capilar, (ii) un modelo de transporte de materia que incluye términos electromigrativos, (iii) un modelo de conductividad eléctrica y conservación de cargas, y (iv) un modelo reactivo de tipo antígeno-anticuerpo. El dominio completo se resuelve utilizando el método de elementos finitos utilizando PETSc-FEM, tanto para los fenómenos de transporte y reacción como para el modelo de flujo por imbibición capilar, que se resuelve con un enfoque tipo Darcy basado en permeabilidades heterogéneas. Se concluye que la realización de ensayos virtuales permite determinar la ventana de trabajo apropiada (en términos de parámetros operativos) para lograr mejorar el límite de detección y el rendimiento global de los dispositivos.Publicado en: Mecánica Computacional vol. XXXV, no. 28.Facultad de Ingenierí

Simulación de la dispersión transversal en dispositivos de microfluídica basados en papel

El desarrollo de plataformas microfluídicas que integran papel y otros derivados de la celulosa ha tenido un notable crecimiento en los últimos cinco años. En efecto, estos soportes son de gran disponibilidad y bajo costo, permiten el transporte de fluidos mediante capilaridad, son compatibles con los sistemas biológicos y permiten la adsorción/desorción de moléculas para implementar diversas reacciones químicas. Estas ventajas hacen que la microfluídica basada en papel se aplique a sistemas de análisis cada vez más diversos, y por lo tanto se vuelve cada vez más necesaria la optimización de las diferentes operaciones unitarias que se realizan en los dispositivos. Varias de esas operaciones, notablemente el mezclado, dilución, separación por tamaños y formación de gradientes, tienen un factor común que es el transporte advectivo-difusivo de especies químicas en la matriz porosa. En este marco, el presente trabajo aborda el modelado y la simulación numérica de la dispersión transversal de especies químicas en un medio poroso. Este estudio básico está dirigido a obtener reglas de escala para el mejor diseño de las operaciones mencionadas en microdispositivos basados en papel a través de diferentes aproximaciones para el término de flujo difusivo en la ecuación de transporte. La idea central es apartarse del modelo Fickiano clásico de difusión, regido por un coeficiente constante tanto en espacio como en tiempo, propio de la naturaleza química de la sustancia transportada y del solvente, para incluir modelos extraídos de literatura reciente. Estos modelos, son esencialmente sensibles (además de la naturaleza química ya mencionada) a las características del medio poroso (permeabilidad, porosidad y ángulo de contacto) y a las características del campo de fluidos para el solvente utilizado. Los modelos se implementarán a través de la herramienta OpenFOAM (R) y se utilizarán a los fines de evaluar diseños de generadores de gradientes microfluídicos en papel y estimar sus potenciales ventajas frente a generadores desarrollados en microcanales clásicos.Publicado en: Mecánica Computacional vol. XXXV, no. 28.Facultad de Ingenierí

Einstein-aether theory, violation of Lorentz invariance, and metric-affine gravity

We show that the Einstein-aether theory of Jacobson and Mattingly (J&M) can be understood in the framework of the metric-affine (gauge theory of) gravity (MAG). We achieve this by relating the aether vector field of J&M to certain post-Riemannian nonmetricity pieces contained in an independent linear connection of spacetime. Then, for the aether, a corresponding geometrical curvature-square Lagrangian with a massive piece can be formulated straightforwardly. We find an exact spherically symmetric solution of our model.Comment: Revtex4, 38 pages, 1 figur

The Study of Customer Satisfaction of Shopee Customers In Malaysia

The main objective of this study is to investigate the factors affect customer satisfaction level among Shopee customers in Malaysia. A set of self-administered questionnaires has been distributed to 200 targeted Shopee users in three states of Malaysia which are Johor, Melaka and Selangor. The five independent variables, which are price, trust, electronic word of mouth, website quality and security have been tested on their relationship towards the dependent variable, which is consumer satisfaction towards online shopping platform, Shopee in Malaysia. The collected data were keyed into SPSS version 25 and followed by using Partial Least Square Structural Equation Modeling (PLS-SEM 3.2.8) to assess the hypothesis. The result of this research given the feedbacks where trust, electronic word of mouth and website quality have significant effect towards consumers satisfaction on Shopee in Malaysia. However, price and security does not show a significant relationship with Shopee’s consumer satisfaction. In conclusion, this study helps to better understand the consumer satisfaction of Shopee’s online shopping services in Malaysia

The ASCEND-ND trial: Study design and participant characteristics

BACKGROUND: Anaemia is common in chronic kidney disease (CKD), and assessment of the risks and benefits of new therapies is important. METHODS: The Anaemia Study in CKD: Erythropoiesis via a Novel prolyl hydroxylase inhibitor Daprodustat-Non-Dialysis (ASCEND-ND) trial includes adult patients with CKD Stages 3-5, not using erythropoiesis-stimulating agents (ESAs) with screening haemoglobin (Hb) 8-10 g/dL, or receiving ESAs with screening Hb of 8-12 g/dL. Participants were randomised to daprodustat or darbepoetin alfa (1:1) in an open- label trial (steering committee- and sponsor-blinded), with blinded endpoint assessment. The co-primary endpoints are mean change in Hb between baseline and evaluation period (average over Weeks 28 to 52) and time to first adjudicated major adverse cardiovascular (CV) event. Baseline characteristics were compared with those of participants in similar anaemia trials. RESULTS: Overall, 3872 patients were randomised from 39 countries (median age 67 years, 56% female; 56% White, 27% Asian, and 10% Black). Median baseline Hb was 9.9 g/dL, blood pressure was 135/74 mmHg and eGFR was 18 mL/min/1.73 m2. Among randomised patients, 53% were ESA non-users, 57% had diabetes and 37% had a history of CV disease. At baseline, 61% of participants were using renin- angiotensin system blockers, 55% were taking statin and 49% oral iron. Baseline demographics were similar to those in other large non-dialysis anaemia trials. CONCLUSION: ASCEND-ND will define the efficacy and safety of daprodustat compared with darbepoetin alfa in the treatment of patients with anaemia associated with CKD not on dialysis

Study design and baseline characteristics of patients on dialysis in the ASCEND-D trial

BACKGROUND: The Anemia Studies in chronic kidney disease (CKD): Erythropoiesis via a Novel prolyl hydroxylase inhibitor (PHI) Daprodustat-Dialysis (ASCEND-D) trial will test the hypothesis that daprodustat is non-inferior to comparator epoetin alfa or darbepoetin alfa for two co-primary endpoints: haemoglobin efficacy and cardiovascular safety. METHODS: We report the trial design, key demographic, clinical, and laboratory findings, and baseline therapies of 2964 patients randomised in the open-label (sponsor-blinded) active-controlled, parallel-group, randomised ASCEND-D clinical trial. We also compare baseline characteristics of ASCEND-D patients with patients who are on dialysis (CKD G5D) enrolled in other large cardiovascular outcome trials (CVOTs) and in the most relevant registries. RESULTS: The median age of patients was 58 years, 43% were female; 67% were white and 16% were black. The median haemoglobin at baseline was 10.4 g/dL. Among randomised patients, 89% were receiving haemodialysis and 11% peritoneal dialysis. Among key co-morbidities, 42% reported a history of diabetes mellitus, and 45% a history of cardiovascular disease. Median blood pressure was 134/74 mmHg. The median weekly dose of epoetin was 5751 units. Intravenous and oral iron use was noted in 64% and 11% of patients, respectively. Baseline demographics were similar to patients with CKD G5D enrolled in other CVOTs and renal patient registries. CONCLUSION: ASCEND-D will evaluate the efficacy and safety of daprodustat compared with epoetin alfa or darbepoetin alfa in the treatment of patients with anaemia with CKD G5D

Identifying Where REDD plus Financially Out-Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional fine-scale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD+ could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO_{2} e) would enable REDD+ to outcompete oil-palm in 55$27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO_{2}e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69$380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD+ competitiveness in tropical floodplain landscapes; and, providing a robust approach for identifying and targeting limited REDD+ funds

Identifying Where REDD+ Financially Out Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional finescale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD + could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US $3 MgCO2e) would enable REDD+ to outcompete oil-palm in 55$27 million to secure these areas for 25 years. Higher carbon offset price (US $30 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69$380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD+ competitiveness in tropical floodplain landscapes; and, providing a robust approach for identifying and targeting limited REDD+ funds

The ASCEND-ND trial: study design and participant characteristics

Background: Anaemia is common in chronic kidney disease (CKD), and assessment of the risks and benefits of new therapies is important. Methods: The Anaemia Study in CKD: Erythropoiesis via a Novel prolyl hydroxylase inhibitor Daprodustat-Non-Dialysis (ASCEND-ND) trial includes adult patients with CKD Stages 3–5, not using erythropoiesis-stimulating agents (ESAs) with screening haemoglobin (Hb) 8–10 g/dL, or receiving ESAs with screening Hb of 8–12 g/dL. Participants were randomised to daprodustat or darbepoetin alfa (1:1) in an open- label trial (steering committee- and sponsor-blinded), with blinded endpoint assessment. The co-primary endpoints are mean change in Hb between baseline and evaluation period (average over Weeks 28 to 52) and time to first adjudicated major adverse cardiovascular (CV) event. Baseline characteristics were compared with those of participants in similar anaemia trials. Results: Overall, 3872 patients were randomised from 39 countries (median age 67 years, 56% female; 56% White, 27% Asian, and 10% Black). Median baseline Hb was 9.9 g/dL, blood pressure was 135/74 mmHg and eGFR was 18 mL/min/1.73 m2. Among randomised patients, 53% were ESA non-users, 57% had diabetes and 37% had a history of CV disease. At baseline, 61% of participants were using renin– angiotensin system blockers, 55% were taking statin and 49% oral iron. Baseline demographics were similar to those in other large non-dialysis anaemia trials. Conclusion: ASCEND-ND will define the efficacy and safety of daprodustat compared with darbepoetin alfa in the treatment of patients with anaemia associated with CKD not on dialysis