1,631 research outputs found

    Preparándonos para el futuro inmediato: rentas estatales, manejo del ambiente y los desafíos del fin del boom petrolero

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    El boom petrolero que alimentó el crecimiento con distribución que Ecuador experimentó durante la última década terminó. Durante estos años se reactivaron viejas prácticas para captar rentas para el estado, y nuevas formas de distribuir esas rentas a la sociedad, pero también para intentar disminuir los impactos de la extracción petrolera en el ambiente. Este modo de funcionamiento está condenado a desaparecer con la crisis de los mercados internacionales de las materias primas. ¿Cómo pueden la sociedad y los gobiernos ecuatorianos prepararse para los efectos de la crisis de rentas del Estado

    Derechos de participación y derecho a participar

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    La participación en la Constitución de 2008 es un elemento fundamental de la organización estatal, pero los instrumentos participativos no son suficientes para concretarla. No se toma en cuenta que el espacio participativo no puede nacer desde las leyes sino a partir de formas de acción política que modifiquen los esquemas tradicionales de toma de decisiones. Se confunde el espacio de lo público con el estatal, la estructura participativa no es otra cosa que aparato de estado. La experiencia: participación vigente en el papel; temas de interés colectivo pasan por la representación o la protesta (casos de trampolín político); nuevas leyes con la falta de participación; y fortalecimiento de un poder personal y autoritario, que no deja espacio para ejercicios democráticos o participativos

    Many-body dynamics of the decay of excitons of different charges in a quantum dot

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    We calculate the photoluminescence spectrum of a single semiconductor quantum dot strongly coupled to a continuum as a function of light frequency, gate voltage, and magnetic field. The spectrum is dominated by the recombination of several excitonic states which can be considered as quantum quenches in which the many-body nature of the system is suddenly changed between initial and final states. This is associated with an Anderson orthogonality catastrophe with a power-law singularity at the threshold. We explain the main features observed experimentally in the region of stability of the trion X-, the neutral exciton X0, and the gate-voltage-induced transition between them.Fil: Andrade Hoyos, Jhon Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Aligia, Armando Ángel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Cornaglia de la Cruz, Pablo Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentin

    Nitrogen status in maize grown at different row spacings and nitrogen availability

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    Barbieri, P. A., Echeverría, H. E., Sainz Rozas, H. R. and Andrade, F. H. 2013. Nitrogen status in maize grown at differentrow spacings and nitrogen availability. Can. J. Plant Sci. 93: 10491058. Improving nitrogen use efficiency (NUE) isimperative to sustainable agriculture. To attain this goal in maize crops (Zea mays L.) there are nitrogen (N) diagnosismethods that enable determination of a crop?s nutritional status by analysis of plant parts. Maize planted in narrow rows(NR) can have increased dry matter (DM), grain yield and accumulated N. However, no reports have been found on theeffect of NR of N in plant diagnosis methods. An experiment was performed over 3 yr to evaluate NR and N fertilizer rateson the N dilution curve, N concentration in grain and chlorophyll content in maize. Treatments consisted of a factorialcombination of row width (70, 52 and 35 cm) and N rate (0 to 180 kg N ha1). The N dilution curves adjusted for fertilizedor control treatments were similar among row spacing. Nitrogen concentration in grain was correlated with relative yield(RY), and similar critical values for N response were similar between row spacings. Leaf chlorophyll content increasedwith N and NR; however, green index (GI) and N sufficiency index (NSI) values were not different between row spacingwhen correlated to RY. These results indicate that response thresholds to N fertilization determined on plant tissue for NRtreatments were similar among row spacings. Thus, there is no need to adjust the response thresholds to N applicationbased on row spacing, as NR did not cause any changes in physiological efficiency (PE) due to the determined proportionalincreases, both in accumulated N in DM and grain yield.Fil: Barbieri, Pablo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; ArgentinaFil: Echeverria, Hernan Eduardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; ArgentinaFil: Sainz Rozas, Hernan Rene. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; ArgentinaFil: Andrade, Fernando Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; Argentin

    Glutamine codon usage and polyQ evolution in primates depend on the Q stretch length

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    Amino acid usage in a proteome depends mostly on its taxonomy, as it does the codon usage in transcriptomes. Here, we explore the level of variation in the codon usage of a specific amino acid, glutamine, in relation to the number of consecutive glutamine residues. We show that CAG triplets are consistently more abundant in short glutamine homorepeats (polyQ, four to eight residues) than in shorter glutamine stretches (one to three residues), leading to the evolutionary growth of the repeat region in a CAG-dependent manner. The length of orthologous polyQ regions is mostly stable in primates, particularly the short ones. Interestingly, given a short polyQ the CAG usage is higher in unstable-in-length orthologous polyQ regions. This indicates that CAG triplets produce the necessary instability for a glutamine stretch to grow. Proteins related to polyQ-associated diseases behave in a more extreme way, with longer glutamine stretches in human and evolutionarily closer nonhuman primates, and an overall higher CAG usage. In the light of our results, we suggest an evolutionary model to explain the glutamine codon usage in polyQ regions

    Lack of Association between BRAF Mutation and MAPK ERK Activation in Melanocytic Nevi

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    The mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase signaling pathway can be activated through mutations of V-RAF murine sarcoma viral oncogene homolog B1 (BRAF) oncogene, frequently found in melanoma (60%), common nevi (CN) (73–82%), and atypical nevi (AN) (52–80%). MAPK activation has been reported between 0 and 22% in nevi, and 86% of primary melanoma, without any knowledge of BRAF mutational status. We studied the correlation of MAPK activation status, BRAF mutation, and B-Raf expression in CN, AN, and melanoma. Using immunohistochemistry, phosphorylated (active) MAPK and B-Raf expression was studied in 24 CN, 21 AN, and 26 primary cutaneous melanomas (PM). BRAF mutations at codon 600 were assessed by PCR-RFLP. Active MAPK was detected in 29% of CN, 48% of AN, and 85% of PM. BRAF mutation was found in 67% of CN, 62% of AN, and 58% of PM. In all, 23% of CN, 54% of AN, and 93% of PM with BRAF mutation have activated MAPK. All lesions expressed B-Raf. BRAF mutation does not seem to be sufficient to produce MAPK activation in melanocytic nevi, and it is suggested that other events are needed to induce MAPK activation, that is, B-Raf overexpression, inhibition of MAPK phosphatases, or suppression of RAF kinase inhibitors

    Scaling of conductance through quantum dots with magnetic field

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    Using different techniques, and Fermi-liquid relationships, we calculate the variation with the applied magnetic field (up to second order) of the zero-temperature equilibrium conductance through a quantum dot described by the impurity Anderson model. We focus on the strong-coupling limit U, where U is the Coulomb repulsion and is half the resonant-level width, and consider several values of the dot level energy E d , ranging from the Kondo regime to the intermediate-valence regime F − E d ∼ , where F is the Fermi energy. We have mainly used the density-matrix renormalization group (DMRG) and the numerical renormalization group (NRG) combined with renormalized perturbation theory (RPT). Results for the dot occupancy and magnetic susceptibility from the DMRG and NRG + RPT are compared with the corresponding Bethe ansatz results for U → ∞, showing an excellent agreement once E d is renormalized by a constant Haldane shift. For U low-energy peak in the spectral density of the dot.Fil: Hamad, Ignacio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Gazza, Claudio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Andrade Hoyos, Jhon Alejandro. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aligia, Armando Ángel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cornaglia de la Cruz, Pablo Sebastian. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Roura Bas, Pablo Gines. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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