Formation of corner waves in the wake of a partially submerged bluff body

We study theoretically and numerically the downstream flow near the corner of a bluff body partially submerged at a deadrise depth Δh into a uniform stream of velocity U, in the presence of gravity, g. When the Froude number, Fr=U/√gΔh, is large, a three-dimensional steady plunging wave, which is referred to as a corner wave, forms near the corner, developing downstream in a similar way to a two-dimensional plunging wave evolving in time. We have performed an asymptotic analysis of the flow near this corner to describe the wave's initial evolution and to clarify the physical mechanism that leads to its formation. Using the two-dimensions-plus-time approximation, the problem reduces to one similar to dam-break flow with a wet bed in front of the dam. The analysis shows that, at leading order, the problem admits a self-similar formulation when the size of the wave is small compared with the height difference Δh. The essential feature of the self-similar solution is the formation of a mushroom-shaped jet from which two smaller lateral jets stem. However, numerical simulations show that this self-similar solution is questionable from the physical point of view, as the two lateral jets plunge onto the free surface, leading to a self-intersecting flow. The physical mechanism leading to the formation of the mushroom-shaped structure is discussed

Considerations on bubble fragmentation models

n this paper we describe the restrictions that the probability density function (p.d.f.) of the size of particles resulting from the rupture of a drop or bubble must satisfy. Using conservation of volume, we show that when a particle of diameter, D0, breaks into exactly two fragments of sizes D and D2 = (D30−D3)1/3 respectively, the resulting p.d.f., f(D; D0), must satisfy a symmetry relation given by D22 f(D; D0) = D2 f(D2; D0), which does not depend on the nature of the underlying fragmentation process. In general, for an arbitrary number of resulting particles, m(D0), we determine that the daughter p.d.f. should satisfy the conservation of volume condition given by m(D0) ∫0D0 (D/D0)3 f(D; D0) dD = 1. A detailed analysis of some contemporary fragmentation models shows that they may not exhibit the required conservation of volume condition if they are not adequately formulated. Furthermore, we also analyse several models proposed in the literature for the breakup frequency of drops or bubbles based on different principles, g(ϵ, D0). Although, most of the models are formulated in terms of the particle size D0 and the dissipation rate of turbulent kinetic energy, ϵ, and apparently provide different results, we show here that they are nearly identical when expressed in dimensionless form in terms of the Weber number, g*(Wet) = g(ϵ, D0) D2/30 ϵ−1/3, with Wet ~ ρ ϵ2/3 D05/3/σ, where ρ is the density of the continuous phase and σ the surface tension

Chemical weathering of the volcanic soils of Isla Santa Cruz (Galápagos Islands, Ecuador)

We present a study on weathering of volcanic soils using 43 profiles (131 horizons) sampled in Santa Cruz Island (Galapagos Islands). Several weathering indices, based on chemical composition, are used. Since the geological material is highly homogeneous the intensity of weathering is mostly related to climatic conditions controlled by topography. There is a gradient of increasing weathering from the arid conditions predominant in the coast to elevations of 400-500 m a.s.l. where much more humid conditions prevail

The ecology of resilience learning in ubiquitous environments to adverse situations

Primary education in Mexico is facing a growing set of challenges that the government has tried to counteract through the use of communication technologies (ICT) in formal education. While these efforts provide support for students and educators, there remains a need for a renewed and contextualized awareness that will re-conceptualize the adverse experiences of students and the importance of resilience in the context of the learning environment. The objective of this document is to give an account of the learning acquired by nine telesecondary students in a rural area of Hidalgo and the student’s benefits of building awareness about the ecology of learning. The paper highlights the process of re-envisioning their experiences that emerged from the various points of views shared in discussion. The study was triangulated by quantitative and qualitative phenomenological and hermeneutical analyses. It was organized into three stages and employed a survey, semi-structured interviews, focus groups and use of the Google-Classroom platform. The hermeneutical analysis of autobiographies and the use of technological resources enhanced the personal analysis of the experiences of the participants. These experiences generated learning that may often be invisible in formal education but can empower critical thinking, collaboration and autonomy of students to become aware of their learning and the scope of their social contribution

The ecology of resilience learning in ubiquitous environments to adverse situations

Primary education in Mexico is facing a growing set of challenges that the government has tried to counteract through the use of communication technologies (ICT) in formal education. While these efforts provide support for students and educators, there remains a need for a renewed and contextualized awareness that will re-conceptualize the adverse experiences of students and the importance of resilience in the context of the learning environment. The objective of this document is to give an account of the learning acquired by nine telesecondary students in a rural area of Hidalgo and the student’s benefits of building awareness about the ecology of learning. The paper highlights the process of re-envisioning their experiences that emerged from the various points of views shared in discussion. The study was triangulated by quantitative and qualitative phenomenological and hermeneutical analyses. It was organized into three stages and employed a survey, semi-structured interviews, focus groups and use of the Google-Classroom platform. The hermeneutical analysis of autobiographies and the use of technological resources enhanced the personal analysis of the experiences of the participants. These experiences generated learning that may often be invisible in formal education but can empower critical thinking, collaboration and autonomy of students to become aware of their learning and the scope of their social contribution

Una revista de presente que mira al futuro

FARMACÉUTICOS COMUNITARIOS da un nuevo paso adelante. Desde su nacimiento en 2009 con su cabecera actual y como heredera de e-farmacéutico comunitario, la revista de ­SEFAC ha experimentado una continua progresión en busca de dos objetivos claros: por un lado, promover, fomentar y consolidar la investigación en farmacia comunitaria en España acercando también a los socios asuntos profesionales relevantes, y, por otro, convertirse en la revista científica de referencia en la publicación de artículos y trabajos de investigación realizados por farmacéuticos comunitarios o de interés para nuestro colectivo.FARMACÉUTICOS COMUNITARIOS da un nuevo paso adelante. Desde su nacimiento en 2009 con su cabecera actual y como heredera de e-farmacéutico comunitario, la revista de ­SEFAC ha experimentado una continua progresión en busca de dos objetivos claros: por un lado, promover, fomentar y consolidar la investigación en farmacia comunitaria en España acercando también a los socios asuntos profesionales relevantes, y, por otro, convertirse en la revista científica de referencia en la publicación de artículos y trabajos de investigación realizados por farmacéuticos comunitarios o de interés para nuestro colectivo

Disorder-Induced First Order Transition and Curie Temperature Lowering in Ferromagnatic Manganites

We study the effect that size disorder in the cations surrounding manganese ions has on the magnetic properties of manganites. This disorder is mimic with a proper distribution of spatially disordered Manganese energies. Both, the Curie temperature and the order of the transition are strongly affected by disorder. For moderate disorder the Curie temperature decreases linearly with the the variance of the distribution of the manganese site energies, and for a disorder comparable to that present in real materials the transition becomes first order. Our results provide a theoretical framework to understand disorder effects on the magnetic behavior of manganites.Comment: 4 pages, three figures include

Negatively buoyant starting jets

The initial development of negatively buoyant jets has been investigated experimentally and numerically, focusing on the role played by gravity in the evolution of the leading vortex ring. Under the experimental conditions considered in this work, the densimetric Froude number, Fr= ρjU²j/[(ρ₀ − ρj) gD] , which represents the ratio between the jet momentum and the buoyancy forces, emerges as the most relevant parameter characterizing the dynamics of the flow. Two different flow regimes have been observed depending on the Froude number: for sufficiently small Fr, the vortex ring generated initially is pushed radially away by gravity forces before it has time to detach from the shear layer originating at the orifice. On the other hand, when the Froude number is larger than a critical value, Fr> Frc∼ 1, the vortex ring detaches from the injection orifice and propagates downstream into the stagnant ambient followed by a trailing jet until it eventually reaches a maximum penetration depth. In order to clarify the mechanisms leading to the transition between the two regimes, and to gain physical understanding of the formation dynamics of negatively buoyant starting jets, the total and the vortex circulation, as well as the trajectory of the vortex center, have been measured and compared to the case of neutrally buoyant jets. Finally, based on the experimental measurements and on the results of the numerical computations, a kinematic model that successfully describes the evolution of both total circulation and vortex trajectory is proposed.This work was supported by the Spanish Ministry of Education under Project Nos. DPI2008-06624-C03-02 and ENE2008-0615-C04. This work has been extracted from the Ph.D. thesis of Marugán-CruzPublicad

Psychological elements explaining the consumer's adoption and use of a website recommendation system: A theoretical framework proposal

The purpose of this paper is to understand, with an emphasis on the psychological perspective of the research problem, the consumer's adoption and use of a certain web site recommendation system as well as the main psychological outcomes involved. The approach takes the form of theoretical modelling. Findings: A conceptual model is proposed and discussed. A total of 20 research propositions are theoretically analyzed and justified. Research limitations/implications: The theoretical discussion developed here is not empirically validated. This represents an opportunity for future research. Practical implications: The ideas extracted from the discussion of the conceptual model should be a help for recommendation systems designers and web site managers, so that they may be more aware, when working with such systems, of the psychological process consumers undergo when interacting with them. In this regard, numerous practical reflections and suggestions are presented

IMMUNEPOTENT CRP enhances cyclophosphamide-induced cytotoxicity through a caspase independent but ROS dependent mechanism in triple negative-breast cancer cells

Background: Breast cancer (BC) is one of the leading causes of cancer death worldwide. Cyclophosphamide (CYP) remains a mainstay in cancer therapy mainly in the triple negative breast cancer subtype (TNBC) in spite of harmful adverse effects and cell death-resistances. To face this, combination of chemotherapies and immunotherapies has been proposed. IMMUNEPOTENT CRP (ICRP) is an immunotherapy that has cytotoxic effects in several cancer cells without affecting peripheral blood mononuclear cells (PBMC) and CD3+ cells, beside improving clinical parameters of chemotherapy-treated patients. The aim of this study was to evaluate the mechanism of cytotoxicity induced by ICRP in combination with CYP (ICRP+CYP) in TNBC cells and their effect in healthy cells. Methods: For this purpose, human and murine breast adenocarcinoma, MDA-MB-231 and 4T1 cells, beside PBMC were treated for 24 hours with ICRP, CYP or ICRP+CYP in different combination ratios for the assessment of cell death. Flow cytometry was used to determine biochemical characteristics of cell death. Results: ANN/PI assays showed that ICRP+CYP induce cell cycle arrest in TNBC cells and potentiated cell death characterized by loss of mitochondrial membrane potential, reactive oxygen species (ROS) production and caspases activation. In addition, ICRP+CYP-cell death is ROS-dependent and caspases-independent in MDA-MB-231 and 4T1 cells. On the other hand, ICRP did not affect CYP-cytotoxicity in PBMC. Conclusions: For all the above, we can propose that the combination of ICRP with CYP is an effective combination therapy, promoting their use even in tumoral cells with defects on proteins implicated in the apoptotic pathway