Planar channel flow of a discontinuous shear-thickening model fluid: Theory and simulation

In this work, an analytical solution for the pressure-driven flow of a discontinuous shear-thickening (DST) fluid in a planar channel is presented. In order to model the fluid rheology, a regularized inverse-biviscous model is adopted. This involves a region of finite thickness to model the sharp jump in viscosity, and it is consistent with momentum conservation. In the limit of vanishing thickness, the truly DST behavior is obtained. Analytical results are validated by numerical simulations under steady and start-up flow using the smoothed particle hydrodynamics method. Flow results are investigated and discussed for different values of the model parameters

SPH modeling and simulation of spherical particles interacting in a viscoelastic matrix

In this work, we extend the three-dimensional Smoothed Particle Hydrodynamics (SPH) non-colloidal particulate model previously developed for Newtonian suspending media in Vázquez-Quesada and Ellero [“Rheology and microstructure of non-colloidal suspensions under shear studied with smoothed particle hydrodynamics,” J. Non-Newtonian Fluid Mech. 233, 37–47 (2016)] to viscoelastic matrices. For the solvent medium, the coarse-grained SPH viscoelastic formulation proposed in Vázquez-Quesada, Ellero, and Español [“Smoothed particle hydrodynamic model for viscoelastic fluids with thermal fluctuations,” Phys. Rev. E 79, 056707 (2009)] is adopted. The property of this particular set of equations is that they are entirely derived within the general equation for non-equilibrium reversible-irreversible coupling formalism and therefore enjoy automatically thermodynamic consistency. The viscoelastic model is derived through a physical specification of a conformation-tensor-dependent entropy function for the fluid particles. In the simple case of suspended Hookean dumbbells, this delivers a specific SPH discretization of the Oldroyd-B constitutive equation. We validate the suspended particle model by studying the dynamics of single and mutually interacting “noncolloidal” rigid spheres under shear flow and in the presence of confinement. Numerical results agree well with available numerical and experimental data. It is straightforward to extend the particulate model to Brownian conditions and to more complex viscoelastic solvents

On the role of Prognostics and Health Management in advanced maintenance systems

The advanced use of the Information and Communication Technologies is evolving the way that systems are managed and maintained. A great number of techniques and methods have emerged in the light of these advances allowing to have an accurate and knowledge about the systems’ condition evolution and remaining useful life. The advances are recognized as outcomes of an innovative discipline, nowadays discussed under the term of Prognostics and Health Management (PHM). In order to analyze how maintenance will change by using PHM, a conceptual model is proposed built upon three views. The model highlights: (i) how PHM may impact the definition of maintenance policies; (ii) how PHM fits within the Condition Based Maintenance (CBM) and (iii) how PHM can be integrated into Reliability Centered Maintenance (RCM) programs. The conceptual model is the research finding of this review note and helps to discuss the role of PHM in advanced maintenance systems.EU Framework Programme Horizon 2020, 645733 - Sustain-Owner - H2020-MSCA-RISE-201

Sensitivity to nitrate and nitrite in pond-breeding amphibians from the Pacific northwest, USA

In static experiments, we studied the effects of nitrate and nitrite solutions on newly hatched larvae of five species of amphibians, namely Rana pretiosa, Rana aurora, Bufo boreas, Hyla regilla, and Ambystoma gracile. When nitrate or nitrite ions were added to the water, some larvae of some species reduced feeding activity, swam less vigorously, showed disequilibrium and paralysis, suffered abnormalities and edemas, and eventually died. The observed effects increased with both concentration and time, and there were significant differences in sensitivity among species. Ambrystoma gracile displayed the highest acute effect in water with nitrate and nitrite. The three ranid species had acute effects in water with nitrite. In chronic exposures, R. pretiosa was the most sensitive species to nitrates and nitrites. All species showed 15-d LC50s lower than 2 mg N-NO2 /L. For both N ions, B. boreas was the least sensitive amphibian. All species showed a high mortality at the U.S. Environmental Protection Agency- recommended limits of nitrite for warm-water fishes (5 mg N-NO2 /L) and a significant larval mortality at the recommended limits of nitrite concentration for drinking water (1 mg N-NO2 The recommended levels of nitrate for warm-water fishes (90 mg N- NO3 /L) were highly toxic for R. pretiosa and A. gracile larvaePeer reviewe

Asociación entre los estilos de aprendizaje y ansiedad en estudiantes de medicina humana

Objetivo: Determinar qué estilo de aprendizaje es más susceptible a presentar ansiedad. Material y Métodos: Es un estudio observacional, transversal y analítico. La población de estudio estuvo constituida alumnos de Medicina Humana en el Campus Trujillo de la Universidad Privada Antenor Orrego que cursan el semestre 2018-2, El total de estudiantes matriculados fue de 2813 alumnos, de los cuales se logró encuestar a un total de 531 estudiantes, excluyéndose 97, dicha muestra represento un nivel de confianza superior al 97% correspondiente al cálculo de muestra para encuesta poblacional según el software EpiInfo®. Se utilizaron 3 cuestionarios validados con un valor α de 0.73, un cuestionario de datos generales, el inventario de estilos de aprendizaje de Kolb V3.1 y el Inventario de desorden de ansiedad generalizada (GAD-7), se utilizó estadística descriptiva, pruebas de Chi-cuadrado y T de Student. Resultados: Se encontró asociación significativa entre los estilos de aprendizaje y ansiedad clínica(p = 0,007), los estilos más predispuestos a la ansiedad clínica fueron el “Divergente” (47,76%) y “Asimilador” (30,35%), se encontró además que el estilo “Convergente” (8,46%), es posiblemente protector frente a la ansiedad clínica(p = 0,036). Otras variables asociadas significativamente a la ansiedad clínica fueron el consumo de tranquilizantes automedicados(p=0,004; OR=20,04) y el sexo femenino(p=0,022; OR=1,63). Conclusiones: Existe asociación significativa entre los estilos de aprendizaje y la ansiedad a nivel clínica(p=0,007), teniendo como estilos de aprendizaje más asociados: “Divergente”(47,76% ) y “Asimilador”(30,35%) . Se considera al estilo de aprendizaje “Convergente” como un factor protector en cuanto a la presencia de ansiedad clínica y se consideran factores predisponentes al sexo femenino y al consumo de tranquilizantes automedicados.Objective: Determine what type of student according to their learning style is more susceptible to present anxiety. Material and Methods: It is an observational, transversal and analytical study. The study population consisted of students of Human Medicine at the Trujillo Campus of the Universidad Privada Antenor Orrego from the period 2018-2, The total number of students enrolled was 2813 students, which would survey a total of 531 students, excluding 97, said sample represented a confidence level higher than 97% i n the calculation of the population sample according to the EpiInfo® software. We used 3 validated questionnaires with an α value of 0.73, a general data questionnaire, the Kolb V3.1 learning styles inventory and the Generalized Anxiety Disorder Inventory (GAD7), a descriptive statistical analysis was made with Chi square tests and Student's T test. Results: A significant association was found between the learning styles and clinical anxiety (p = 0.007), the styles most predisposed to clinical anxiety were the ""Divergent"" (47.76%) and ""Assimilator"" (30.35%). Also was found that the ""Convergent"" style (8.46%) is possibly protective against clinical anxiety (p = 0.036). Other variables significantly associated with clinical anxiety were the consumption of self-administered tranquilizers (p = 0.004, OR = 20.04) and the female sex (p = 0.022, OR = 1.63). Conclusions: There is a significant relationship between learning styles and anxiety at the clinical level (p = 0.007), having as more associated learning styles: ""Divergent"" (47.76%) and ""Assimilator"" (30.35%). Consider the ""Convergent"" learning style as a protective factor in the presence of clinical anxiety and predisposing factors were the female sex and the consumption of self-administered tranquilizers.Tesi

Comportamiento agonístico de Salamandra salamandra morenica en el Parque Natural Sierra Norte de Sevilla

Peer reviewe

Realistic levels of a fertilizer impair Iberian newt embryonic development

A wide variety of agricultural chemicals with potential to affect amphibian health are released into the environment daily. Most of these chemicals are xenobiotic compounds that are highly toxic to embryos, tadpoles, and terrestrial stages. Other substances that occur in pristine environments at harmless concentrations, such as inorganic nitrogenous compounds, may reach potentially toxic levels as a consequence of certain human activities, including the application of fertilizers. Most of the studies that analyze the effects of inorganic nitrogen on amphibian embryos are conducted with anurans, whereas little information exists regarding urodeles. Embryos of newts and salamanders usually exhibit longer times to hatch than frogs and toads. A longer hatching time results in a longer exposure of embryos to diffuse environmental pollution and therefore a higher risk of suffering toxic effects during the embryonic stage. We demonstrate that ammonium nitrate, a widely used nitrogenous fertilizer, at concentrations used in areas of high agricultural intensity, affects embryonic development of the Iberian newt (Lissotriton boscai). Although ammonium nitrate did not have significant lethal effects, it reduced the growth rate of exposed embryos, which were 9.6% smaller than controls. Hatching synchrony remained similar across treatments, and hatching date was not affected by ammonium nitrate, indicating that the effect on growth was not time- dependent. Researchers have demonstrated fitness costs in smaller than average tadpoles, suggesting that ammonium nitrate exposure could have long-term negative consequences for the Iberian newt.Peer reviewe