A two-layer shallow water model for bedload sediment transport: convergence to Saint-Venant-Exner model

A two-layer shallow water type model is proposed to describe bedload sediment transport. The upper layer is filled by water and the lower one by sediment. The key point falls on the definition of the friction laws between the two layers, which are a generalization of those introduced in Fern\'andez-Nieto et al. (ESAIM: M2AN, 51:115-145, 2017). This definition allows to apply properly the two-layer shallow water model for the case of intense and slow bedload sediment transport. Moreover, we prove that the two-layer model converges to a Saint-Venant-Exner system (SVE) including gravitational effects when the ratio between the hydrodynamic and morphodynamic time scales is small. The SVE with gravitational effects is a degenerated nonlinear parabolic system. This means that its numerical approximation is very expensive from a computational point of view, see for example T. Morales de Luna et al. (J. Sci. Comp., 48(1): 258-273, 2011). In this work, gravitational effects are introduced into the two-layer system without such extra computational cost. Finally, we also consider a generalization of the model that includes a non-hydrostatic pressure correction for the fluid layer and the boundary condition at the sediment surface. Numerical tests show that the model provides promising results and behave well in low transport rate regimes as well as in many other situations

Turbulence and Chaos in Anti-de-Sitter Gravity

Due to the AdS/CFT correspondence the question of instability of Anti-de-Sitter spacetimes sits in the intersection of mathematical and numerical relativity, string theory, field theory and condensed matter physics. In this essay we revisit that important question emphasizing the power of spectral methods and highlighting the effectiveness of standard techniques for studying nonlinear dynamical systems. In particular we display explicitly how the problem can be modeled as a system on nonlinearly coupled harmonic oscillators. We highlight some of the many open questions that stem from this result and point out that a full understanding will necessarily required the interdisciplinary cooperation of various communities.Comment: 6 pages, 12 figures. Essay awarded honorable mention in the Gravity Research Foundation essay competition 201

The Potential of Using Grapefruit Peel as a Natural Support for Yeast Immobilization During Beer Fermentation

The potential use of grapefruit peel as support material for yeast immobilization during beer fermentation was evaluated. After conditioning, FTIR analysis revealed a higher quantity of methoxy (–OCH3) groups, suggesting that lignin is the major component of the support. Cell adhesion onto the conditioned support in 12°Plato laboratory malt wort was evaluated, observing a maximal cell adhesion (2.25 · 109 cells/gram of dried support) at 20 h of cultivation, remaining almost constant in the subsequent time points. Evaluations of the fermentative behaviour of the biocatalyst at 15±0.5 °C in a 14°Plato laboratory malt wort indicated good stability in terms of physical integrity (confirmed by SEM observation). The fermentation time was shortened to four days, and the rates of reducing sugar consumption and ethanol production were improved when compared to fermentations carried out with free suspended cells. These results show a promising potential of grapefruit peel as support material in beer fermentation. This work is licensed under a Creative Commons Attribution 4.0 International License

Determinants of Irrigation Farmers\u27 Crop Choice and Acreage Allocation Decisions: Opportunities for Extension Service Delivery

A survey of Georgia irrigators focused on the determinants of farmers\u27 crop choice and crop acreage allocation decisions was conducted. The survey also addressed farmer interest in open-access information and decision support programs delivered by the University of Georgia via the Internet. Results indicate crop choice and acreage decisions are heavily influenced by rotational considerations, but such considerations are not viewed as strict constraints. Crop futures prices and expected input costs are also important factors. Farmers expressed considerable interest in accessing information relevant to their crop choice and acreage allocation decision on the Internet at a university-run Web site

Reversal of hepatorenal syndrome type 1 with terlipressin plus albumin vs. placebo plus albumin in a pooled analysis of the OT-0401 and REVERSE randomised clinical studies

Background The goal of hepatorenal syndrome type 1 (HRS-1) treatment is to improve renal function. Terlipressin, a synthetic vasopressin analogue, is a systemic vasoconstrictor used for the treatment of HRS-1, where it is available. Aim To compare the efficacy of terlipressin plus albumin vs. placebo plus albumin in patients with HRS-1. Methods Pooled patient-level data from two large phase 3, randomised, placebo-controlled studies were analysed for HRS reversal [serum creatinine (SCr) value ≤133 μmol/L], 90-day survival, need for renal replacement therapy and predictors of HRS reversal. Patients received intravenous terlipressin 1–2 mg every 6 hours plus albumin or placebo plus albumin up to 14 days. Results The pooled analysis comprised 308 patients (terlipressin: n = 153; placebo: n = 155). HRS reversal was significantly more frequent with terlipressin vs. placebo (27% vs. 14%; P = 0.004). Terlipressin was associated with a more significant improvement in renal function from baseline until end of treatment, with a mean between-group difference in SCr concentration of −53.0 μmol/L (P \u3c 0.0001). Lower SCr, lower mean arterial pressure and lower total bilirubin and absence of known precipitating factors for HRS were independent predictors of HRS reversal and longer survival in terlipressin-treated patients. Conclusions Terlipressin plus albumin resulted in a significantly higher rate of HRS reversal vs. albumin alone in patients with HRS-1. Terlipressin treatment is associated with improved renal function

Use of Machine Learning Models of the ”Transformers” Type in the Construction of Services in a Gamified Web app.

The purpose of this document is to describe the use of a natural language processing model in the multiplatform system ”Gamivity” by means of a sentence similarity algorithm to offer a personalized experience module based on the conceptual relationship between questions. For the selection process, certain criteria were chosen that will allow several pre-trained models under the “Transformers” architecture for evaluation, later. These criteria were the language with which the model was altered; Python was the programming language used for the implementation. Regarding the evaluation phase of the selected models, the ”Sentence Transformers” library of the Python programming language was used. In addition, a work environment analogous to the module present in the ”Gamivity” system was built, in which the development platform ”Google Colab” was used to test these models. The criteria for choosing the candidate model were based on its effectiveness in relation to questions as well as the computational cost involved while performing the operations in the said model Based on the applied methodology, the model that yielded the best results was ”paraphrase-multilingual- MiniLM-L12-v2,” modified with a large corpus of text in Spanish and 50 other languages, which showed a degree of precision. When it comes to conceptually relating the questions provided it was found to be optimal, having relatively low computational cost when performing these operations. Keywords: sentence transformers, sentence similarity, relate questions, personalized learning. Resumen El presente documento, tiene como propósito el de describir la utilización de un modelo de procesamiento de lenguaje natural en el sistema multiplataforma “Gamivity”, por medio de un algoritmo de similitud de oraciones para ofrecer un módulo de experiencia personalizada a partir de la relación conceptual entre preguntas. Para el proceso de selección, se establecieron ciertos criterios que permitieron elegir varios modelos pre entrenados bajo la arquitectura “Transformers” para su posterior evaluación. Dichos criterios, fueron el idioma con el que fue entrenado el modelo, así como que el lenguaje de programación utilizado para la implementación fuese Python. En lo que concierne a la fase de evaluación de los modelos seleccionados, se hizo uso de la biblioteca “Sentence Transformers” del lenguaje de programación Python, además se construyó un entorno de trabajo análogo al módulo presente en el sistema “Gamivity”, en la plataforma de desarrollo “Google Colab” para poner a prueba dichos modelos, los criterios para la elección del modelo candidato, se resumen en la eficacia a la hora de relacionar preguntas, así como el coste computacional a la hora de realizar las operaciones involucradas en dicho proceso. A partir de la metodología aplicada, el modelo que mejor resultados generó fue “paraphrase-multilingual-MiniLM L12-v2”, entrenado con un gran corpus de texto en español, así como de otros 50 idiomas, el cual mostró un grado de precisión óptimo a la hora de relacionar conceptualmente las preguntas proporcionadas, así como su relativo bajo coste computacional a la hora de efectuar dichas operaciones. Palabras Clave: sentence transformers, sentence similarity, relacionar preguntas, aprendizaje personalizado

Black Holes with Varying Flux: A Numerical Approach

We present a numerical study of type IIB supergravity solutions with varying Ramond-Ramond flux. We construct solutions that have a regular horizon and contain nontrivial five- and three-form fluxes. These solutions are holographically dual to the deconfined phase of confining field theories at finite temperature. As a calibration of the numerical method we first numerically reproduce various analytically known solutions including singular and regular nonextremal D3 branes, the Klebanov-Tseytlin solution and its singular nonextremal generalization. The horizon of the solutions we construct is of the precise form of nonextremal D3 branes. In the asymptotic region far away from the horizon we observe a logarithmic behavior similar to that of the Klebanov-Tseytlin solution.Comment: 40 pages, 15 figure

Dysfunctional grief related to COVID-19 in Latin America

The characteristics associated with COVID-19-related dysfunctional grief suggest that we are most likely facing a “dysfunctional grief pandemic” due to COVID-19. Thus this preliminary study reports frequencies of dysfunctional grief in ten Latin American countries that varied between 7.3% in Brazil and 14.6% in El Salvador. This highlights a greater need for Latin American countries to work together to improve the accessibility of treatment for dysfunctional grief