2,248 research outputs found

    Sobre la evolución contemporánea de la teoría de los derechos del hombre

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    Beads, bubbles and drops in microchannels: stability of centered position and equilibrium velocity

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    Understand and predict the dynamics of dispersed micro-objects in microfluidics is crucial in numerous natural, industrial and technological situations. In this paper, we experimentally characterized the equilibrium velocity VV and lateral position ε\varepsilon of various dispersed micro-objects such as beads, bubbles and drops, in a cylindrical microchannel over an unprecedent wide range of parameters. By systematically varying the dimensionless object size (d[0.1;1]d \in [0.1; 1]), the viscosity ratio (λ[102;[\lambda \in [10^{-2}; \infty[), the density ratio (φ[103;2]\varphi \in [10^{-3}; 2]), the Reynolds number ([102;102]\Re \in [10^{-2}; 10^2]), and the capillary number (Ca[103;0.3]\text{Ca} \in [10^{-3}; 0.3]), we offer a general study exploring various dynamics from the nonderformable viscous regime to the deformable visco-inertio-capillary regime, thus enabling to highlight the sole and combined roles of inertia and capillary effects on lateral migration. The experiments are compared and well-agree with a steady 3D Navier-Stokes model for incompressible two-phase fluids including both the effects of inertia and possible interfacial deformations. This model enables to rationalize the experiments and to provide an exhaustive parametric analysis on the influence of the main parameters of the problem, mainly on two aspects: the stability of the centered position and the velocity of the dispersed object. Interestingly, we propose a useful correlation for the object velocity VV as functions of the dd, ε\varepsilon and λ\lambda, obtained in the Re=Ca=0\text{Re}=\text{Ca}=0 limit, but actually valid for a larger range of values of Re\text{Re} and Ca\text{Ca} in the linear regimes.Comment: 22 pages, 11 figures, submitted to Journal of Fluid Mechanic

    Sensitivity analysis of the hydrological and hydraulic parameters of the SWMM model and its application in urban drainage systems

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    Simulation models are widely used for the design and management of urban drainage systems, such as the SWMM Stormwater Management Model. However, the quality of its results is directly related to the quality of the data provided, since an incorrect estimate of these may lead to a different behavior than expected in the real case. There is uncertainty in many hydrological and hydraulic input parameters of the model, since most of them are estimated and there are no measured data to calibrate it. In this work a sensitivity analysis is carried out to various parameters to detect the most influential in the simulation of urban drainage systems. It consisted of locally varying each of the parameters and assessing their influence on the variation of the flows and maximum levels at a point in the Copacoa Urbanization, Palavecino municipality of the Lara State, Venezuela. From the results obtained, it is concluded that for simulations of urban watersheds where impervious areas predominate, the least sensitive method for the generation of the rain hietrogram is that of alternate blocks, while the one with the greatest variability is the triangular hietrogram. Regarding the basin component, the most sensitive parameters are the percentage of impermeable area, the slope of the basin and the Manning coefficient assigned to the impermeable area. In relation to the duct, the Manning coefficient parameter also presented an appreciable sensitivity, but of a lesser magnitude compared to those obtained for the basin component

    Vulnérabilités liées à l'eau dans les Andes vénézuéliennes : influences des relations sociétés/hydrosystèmes dans le cas de Santa-Cruz-de-Mora

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    International audienceDes mutations agricoles sont survenues au cours des dernières décennies dans les Andes vénézuéliennes. Cette région autrefois grande productrice de café a vu sa production baisser au profit du maraîchage irrigué et du pastoralisme. Nous avons mené 2 démarches parallèles : la caractérisation des changements d'occupation du sol afin de mettre en perspective le discours des habitants ; et l'analyse des représentations sociales des risques liés à l'eau, restitués plus largement dans les représentations des hydrosystèmes

    Differential β₂-adrenergic receptor expression defines the phenotype of non-tumorigenic and malignant human breast cell lines

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    Breast cancer is the most frequent malignancy in women. Several reports demonstrated that adrenergic receptors (ARs) are involved in breast cancer. Here we observed that epinephrine (Epi), an endogenous AR agonist, caused opposite effects in non-tumorigenic (MCF-10A and HBL-100) and tumor cells (MCF-7 and MDA-MB-231). Thus, Epi, in non-tumor breast cells, as well as isoproterenol (β-agonist), in all cell lines, maintained a benign phenotype, decreasing cell proliferation and migration, and stimulating cell adhesion. β-AR expression and cAMP levels were higher in MCF-10A than in MCF-7 cells. β₂-AR knock-down caused a significant increase of cell proliferation and migration, and a decrease of cell adhesion both in basal and in Iso-stimulated conditions. Coincidently, β₂-AR over-expression induced a significant decrease of cell proliferation and migration, and an increase of cell adhesion. Therefore, β₂-AR is implied in cell phenotype and its agonists or antagonists could eventually complement cancer therapy.Fil: Gargiulo, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Copsel, Sabrina Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología; ArgentinaFil: Rivero, Ezequiel Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Galés, Céline. Inserm; FranciaFil: Sénard, Jean Michel. Inserm; FranciaFil: Luthy, Isabel Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Davio, Carlos Alberto. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología; ArgentinaFil: Bruzzone, Ariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentin

    Methamphetamine blunts Ca2+ currents and excitatory synaptic transmission through D1/5 receptor-mediated mechanisms in the mouse medial prefrontal cortex

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    Psychostimulant addiction is associated with dysfunctions in frontal cortex. Previous data demonstrated that repeated exposure to methamphetamine (METH) can alter prefrontal cortex (PFC)-dependent functions. Here, we show that withdrawal from repetitive non-contingent METH administration (7 days, 1 mg/kg) depressed voltage-dependent calcium currents (ICa) and increased hyperpolarization-activated cation current (IH) amplitude and the paired-pulse ratio of evoked excitatory postsynaptic currents (EPSCs) in deep-layer pyramidal mPFC neurons. Most of these effects were blocked by systemic co-administration of the D1/D5 receptor antagonist SCH23390 (0.5 and 0.05 mg/kg). In vitroMETH (i.e. bath-applied to slices from naïve-treated animals) was able to emulate its systemic effects on ICa and evoked EPSCs paired-pulse ratio. We also provide evidence of altered mRNA expression of (1) voltage-gated calcium channels P/Q-type Cacna1a (Cav2.1), N-type Cacna1b (Cav2.2), T-type Cav3.1 Cacna1g, Cav3.2 Cacna1h, Cav3.3 Cacna1i and the auxiliary subunit Cacna2d1 (α2δ1); (2) hyperpolarization-activated cyclic nucleotide-gated channels Hcn1 and Hcn2; and (3) glutamate receptors subunits AMPA-type Gria1, NMDA-type Grin1 and metabotropic Grm1 in the mouse mPFC after repeated METH treatment. Moreover, we show that some of these changes in mRNA expression were sensitive D1/5 receptor blockade. Altogether, these altered mechanisms affecting synaptic physiology and transcriptional regulation may underlie PFC functional alterations that could lead to PFC impairments observed in METH-addicted individuals.Fil: Gonzalez, Betina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Rivero Echeto, Maria Celeste Solange. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Muñiz, Javier Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Cadet, Jean Lud. National Institutes of Health; Estados UnidosFil: Garcia Rill, Edgar. University Of Arkansas For Medical Sciences; Estados UnidosFil: Urbano Suarez, Francisco Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Bisagno, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; Argentin
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