Insights into the links between microstructure and Bishop's X parameter for unsaturated soils

International audienceIn recent years, Bishop's proposal for a generalized stress extending Terzaghi's stress to unsaturated states gained a large audience. Despite the complexity introduced in some aspects of modelling or stress representation, such an approach allows to model in a simple manner particular features of unsaturated soils behaviour. In this paper, an alternative choice for this parameter is proposed and validated using either shear strength or elastic stiffness experimental data from a set of soils ranging from almost granular materials to high plasticity clays. A physical interpretation in terms of microstructurally trapped water is provided. It is shown that the amount of trapped water is closely linked to the definition of X. When the amount of non-free water increases (increasing plasticity indices), a significant deviation of X values from the degree of saturation is observed. It is thus concluded that some care must be taken when assuming as generally done that Bishop's X parameter equals the degree of saturation of water

A microstructurally-based effective stress for unsaturated soils

International audienceCurrent alternative choices of stress state variables in unsaturated soils are described and compared, with a special focus on the use of an effective stress. Experimental data on stiffness and shear strength evolution with suction suggest that the proportion of suction contributing to the effective stress is often much smaller than predicted by the term ‘suction times degree of saturation' generally used in effective stress expressions of the Bishop type. It is suggested that effective stress in unsaturated soils should be related to soil microstructure. An effective degree of saturation is defined as describing the volume of water partially filling the soil macroporosity. This effective degree of saturation defines the proportion of the prevailing suction that actually contributes to the effective stress. Two alternative expressions (piecewise linear and non-linear) are proposed for the effective degree of saturation. They offer a similar performance. Available data on stiffness and shear strength variation with suction of a few different soils, ranging from a markedly granular material to high-plasticity clay, have been analysed. The analysis supports the proposed microstructural interpretation of the effective stress. Indeed, for granular soils the effective degree of saturation is almost equal to the total degree of saturation, and therefore the Bishop-type expression generally used as an effective stress is recovered. As the soil becomes more plastic, the proportion of free water reduces, and the contribution of suction to the effective stress reduces. At the limit, when the proportion of free water is negligible (this is the case of high-plasticity clays at high values of suction) the proposed effective stress reduces to the net stress (excess of total stress over the air pressure). The proposed effective stress equation may be identified if information on the amount of immobile water is available for a given soil. Water retention or porosimetry data provide this information. This has been shown by comparing the present proposal with independently obtained information about immobile water in high-plasticity clays

Is the degree of saturation a good candidate for Bishop's X parameter?

International audienceIn unsaturated soil mechanics, the quest for an effective stress playing the same role as Terzaghi's effective stress does for saturated soils has introduced a long standing debate, dating back to the 1960s. Several contributions have been proposed since the early work of Bishop. It is well recognized to date that a single constitutive stress is not sufficient by itself to catch the main features of the behaviour of unsaturated soils and it is often combined with matric suction. In this paper, focus is given to a largely used formulation for such a constitutive stress, based on the use of an averaged pore pressure. In particular, this paper discusses on thermodynamics bases the validity of the choice of the factor X weighting the fluid pressures contribution to the constitutive stress. This factor is usually assumed to be equal to the degree of saturation of water. In this work it is shown that the choice of this natural candidate implies restrictive assumptions on the plastic flow rule. As shown from experimental data obtained from a literature review, this choice may not be pertinent for certain classes of materials, particularly high plasticity clays

Las fundaciones Murrieta de Santurce siglos XIX y XX

En este artículo se aborda el estudio sobre el origen de la Fundación Murrieta de Santurce, la procedencia de su promotor y de los avatares de la primera organización de sus fundaciones. Todo ello en el marco de la normativa nacional para la regulación de estas instituciones y de los problemas de una época compleja

Reversing downstream consequences of school hiatus on reading in disadvantaged, at-risk children

The spread of COVID-19 has led to the disruption of K-12 education for about 90% of the world's student population. The effects on children's academic development are unknown. We examined how disruption in schooling over three consecutive summers in disadvantaged minority children affects reading and whether an intensive intervention can ameliorate these effects. Our data were collected prior to the COVID-19 pandemic. We applied Latent Change Score models to examine developmental trends in a longitudinal study of reading in 111 economically disadvantaged children, assessed biannually from grades 1 to 4, including 3 summers (for a total of 6 months of school hiatus). The students fell behind the normative population in their ability to understand written texts, a decrease in their relative percentile of 0.25 of a standard deviation each summer, and an effect 3-4 times greater than prior studies suggested. Compared to children in a comparison group, children who received an evidence-based intervention during the school year were better able to maintain their reading scores. These findings provide evidence that disruptions in schooling, for example, those implemented to slow the spread of COVID-19, may have a significant detrimental effect on the reading abilities of disadvantaged children and that children who received a reading intervention were better able to maintain their reading scores during the hiatus. It is critical that policy makers prioritize the allocation of necessary resources to minimize the negative effects on reading this pandemic has wrought on these most disadvantaged children.Support for the work reported in this article was provided by: The Seedlings Foundation. EE was supported by the Ministry of Science and Innovation of Spain (ref. PID2019-107570GAI00 / AEI / doi: https://doi.org/10.13039/501100011033

Paleogene succession underlying the La Espina Thrust (boundary between the Cantabrian and West-asturianleonese zones). Tectonic implications

Este artículo da a conocer la existencia de una sucesión paleógena, datada mediante su contenido polínico, bajo el cabalgamiento que separa las zonas Cantábrica y Asturoccidental-leonesa. Esta sucesión paleógena se apoya sobre arenas y arcillas con facies similares a unidades cretácicas como la Formación Utrillas. El cobijamiento de dicha sucesión por el cabalgamiento varisco antes mencionado, implica que éste fue reactivado durante la deformación AlpinaThis paper describes the stratigraphy and structural setting of a new outcrop of Paleogene sediments, whose age has been determined from their pollen content. These sediments overlie sands and clays of presumed Cretaceous age and underlie the La Espina Thrust, that is the boundary between two Variscan geological domains: the Cantabrian and Westasturian-leonese zones. The Alpine deformation caused reactivation of the La Espina Variscan Thrust as a reverse faul

Racotumomab: an anti=idiotype vaccine related to N=glycolyl=containing=gangliosides: Preclinical and clinical data

Neu-glycolyl (NeuGc)-containing gangliosides are attractive targets for immunotherapy with anti-idiotype mAbs, because these glycolipids are not normal components of the cytoplasmic membrane in humans, but their expression has been demonstrated in several human malignant tumors. Racotumomab is an anti-idiotype mAb specific to P3 mAb, an antibody which reacts to NeuGc-containing gangliosides, sulfatides, and other antigens expressed in tumors. Preparations containing racotumomab were able to induce a strong anti-metastatic effect in tumor-bearing mice. Different Phase I clinical trials have been conducted in patients with advanced melanoma, breast cancer, and lung cancer. The results of these clinical trials demonstrated the low toxicity and the high immunogenicity of this vaccine. The induced antibodies recognized and directly killed tumor cells expressing NeuGcGM3. A Phase II/III multicenter, controlled, randomized, double blind clinical trial was conducted to evaluate the effect of aluminum hydroxide-precipitated racotumomab vaccine in overall survival in patients with advanced non-small cell lung cancer. The clinical results of this study showed a significant clinical benefit in the patients who were treated with the anti-idiotype vaccine.Fil: Vazquez, Ana M.. Center of Molecular Immunology; CubaFil: Hernandez, Ana M.. Center of Molecular Immunology; CubaFil: Macias, Amparo. Center of Molecular Immunology; CubaFil: Montero, Enrique. Center of Molecular Immunology; CubaFil: Gomez, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Alonso, Daniel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Gabri, Mariano Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Gomez, Roberto E.. Elea Laboratories; Argentin

Sensitivity of tumor cells towards CIGB-300 anticancer peptide relies on its nucleolar localization

CIGB-300 is a novel anticancer peptide that impairs the casein kinase 2-mediated phosphorylation by direct binding to the conserved phosphoacceptor site on their substrates. Previous findings indicated that CIGB-300 inhibits tumor cell proliferation in vitro and induces tumor growth delay in vivo in cancer animal models. Interestingly, we had previously demonstrated that the putative oncogene B23/nucleophosmin (NPM) is the major intracellular target for CIGB-300 in a sensitive human lung cancer cell line. However, the ability of this peptide to target B23/NPM in cancer cells with differential CIGB-300 response phenotype remained to be determined. Interestingly, in this work, we evidenced that CIGB-300's antiproliferative activity on tumor cells strongly correlates with its nucleolar localization, the main subcellular localization of the previously identified B23/NPM target. Likewise, using CIGB-300 equipotent doses (concentration that inhibits 50% of proliferation), we demonstrated that this peptide interacts and inhibits B23/NPM phosphorylation in different cancer cell lines as evidenced by in vivo pull-down and metabolic labeling experiments. Moreover, such inhibition was followed by a fast apoptosis on CIGB-300-treated cells and also an impairment of cell cycle progression mainly after 5 h of treatment. Altogether, our data not only validates B23/NPM as a main target for CIGB-300 in cancer cells but also provides the first experimental clues to explain their differential antiproliferative response. Importantly, our findings suggest that further improvements to this cell penetrating peptide-based drug should entail its more efficient intracellular delivery at such subcellular localization.Fil: Perera, Yasser. Centro de Ingeniería Genética y Biotecnología; CubaFil: Costales, Heydi C.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Diaz, Yakelin. Centro de Ingeniería Genética y Biotecnología; CubaFil: Reyes, Osvaldo. Centro de Ingeniería Genética y Biotecnología; CubaFil: Farina, Hernán Gabriel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mendez, Lissandra. Centro de Ingeniería Genética y Biotecnología; CubaFil: Gómez, Roberto E.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Acevedo, Boris E.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perea, Silvio E.. Centro de Ingeniería Genética y Biotecnología; Cub

Large Nc QCD and Harmonic Sums

In the Large-Nc limit of QCD, two--point functions of local operators become Harmonic Sums. I review some properties which follow from this fact and which are relevant for phenomenological applications. This has led us to consider a class of Analytic Number Theory Functions as toy models of Large-Nc QCD which I also discuss.Comment: Based on my talk at "Raymond Stora's 80th Birthday Party", LAPP, July 11th 201

CIGB-300, a proapoptotic peptide, inhibits angiogenesis in vitro and in vivo

We have previously demonstrated that a proapoptotic cyclic peptide CIGB-300, formerly known as P15-Tat delivered into the cells by the cell-penetrating peptide Tat, was able to abrogate the CK2-mediated phosphorylation and induce tumor regression when injected directly into solid tumors in mice or by systemic administration. In this work, we studied the role of CIGB-300 on the main events that take place in angiogenesis. At non-cytotoxic doses, CIGB-300 was able to inhibit adhesion, migration, and tubular network formation induced by human umbilical vein endothelial cells (HUVEC) growing upon Matrigel in vitro. Likewise, we evaluated the cellular penetration and localization into the HUVEC cells of CIGB-300. Our results confirmed a quick cellular penetration and a cytoplasmic accumulation in the early minutes of incubation and a translocation into the nuclei beginning at 12. h of treatment, with a strong presence in the perinuclear area. A microarray analysis was used to determine the genes affected by the treatment. We observed that CIGB-300 significantly decreased four genes strongly associated with tubulogenesis, growth, and differentiation of endothelial cells. The CIGB-300 was tested in vivo on chicken embryo chorioallantoic membranes (CAM), and a large number of newly formed blood vessels were significantly regressed. The results suggested that CIGB-300 has a potential as an antiangiogenic treatment. The mechanism of action may be associated with partial inhibition of VEGF and Notch pathways.Fil: Farina, Hernán Gabriel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Benavent Acero, Fernando Rodrigo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Perera, Yasser. Center for Genetic Engineering and Biotechnology; CubaFil: Rodríguez, Arielis. Center for Genetic Engineering and Biotechnology; CubaFil: Perea, Silvio E.. Center for Genetic Engineering and Biotechnology; CubaFil: Acevedo Castro, Boris. Center for Genetic Engineering and Biotechnology; CubaFil: Gomez, Roberto. No especifíca;Fil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin