498 research outputs found

    The Impact of Unconditional Cash Transfers on Nutrition: The South African Child Support Grant

    Get PDF
    In light of research that has argued that the income elasticity of nutrition is low, the goal of a new generation of cash transfer programmes to boost the nutrition of poor families' children may seem surprising. This observation applies especially to South Africa's unconditional Child Support Grant (CSG), in which cash grants are made to families with no strings attached. However, in contrast to the market-generated income increases that identified low nutritional elasticities in the earlier studies, the income increases generated by the South African cash transfers are almost exclusively assigned to women. Taking advantage of a slow programme rollout that created exogenous variation in the extent of CSG treatment received by beneficiaries in the province of KwaZulu-Natal, this Working Paper utilizes the continuous treatment method of Hirano and Imbens (2004) to estimate the impact of these transfers on child nutrition as measured by child height-for-age. Large dosages of CSG treatment early in life are shown to significantly boost child height. Drawing on the best estimates in the literature, these estimated height gains in turn suggest large adult earnings increases for treated children and a discounted rate of return on CSG payments of between 160 per cent and 230 per cent.Nutrition, cash transfers, continuous treatment estimator, South Africa, poverty

    Embryo rescue from seedless grapevines (Vitis vinifera L.) treated with growth retardants

    Get PDF
    The effects of two retardants (CCC and paclobutrazol) and the new compound XE 1019, applied before grapevine anthesis, were studied in order to increase the number of fertilised embryos and growing plantlets derived from in ovulo culture of seedless cultivars CG 102.011, Emperatriz and Malvinas. No significant differences were detected between treatments with CCC (400 and 800 mg . l-1, applied 2, 3 and 4 weeks before bloom), and the control in the cv. CG 102.011. The number of growing plantlets at 10 weeks after anthesis and at maturity was significantly higher than that from 8 weeks. In applications closer to bloom, CCC treatments increased the number of ovules per berry in the cultivars assayed. From all cultivars, only CG 102.011 showed a significant increase in plantlet production after CCC treatment when clusters were harvested the 10th week after bloom. It is believed that CCC would act through inhibition of endogenous gibberellin synthesis as the cause of ovule abortion. The idea is based on the fact that gibberellic acid can induce seedlessness in some seeded cultivars

    Long-term behaviour of Nb and Cr nitrides nanostructured coatings under steam at 650°C. Mechanistic considerations.

    Get PDF
    There is an increasing demand for steam power plants to operate in super-critical conditions i.e. temperatures in excess of 600°C. Under these conditions creep resistant ferritic steels oxidize and therefore require coatings in order to last. Physical vapor deposition and especially High Power Impulse Magnetron Sputtering deposited CrN/NbN nano-scale multilayer coatings with a 2.45 Cr/Nb ratio showed excellent performance when exposed to 650 °C in pure steam environment up to 2,000 h. However the role of Nb in offering protection is unclear. In order to study the long term behaviour of this type of coatings as well as to determine the influence of Nb on their oxidation resistance, a CrN/NbN coating with a 1.16 Cr/Nb ratio was studied for 12,650 h. The coating is hard, well adhered and resistant to environmental corrosion, which are properties required in particular for coatings to be applied on turbine blades. The coating also protects P92 from steam oxidation at 650º C, however coating growth defects influence significantly the oxidation resistance. The long-time exposure allowed to study the protection/ degradation mechanisms provided by this type of ceramic coatings. It was found that oxide nodules grow due to the presence of coating defect originated from substrate defects. Moreover, the higher Nb CrN/NbN coating slowly oxidizes, consuming the coating to a large extent after 12,650 h. As a result, protective oxides containing Cr and Nb are developed, remaining well attached to the substrate for at least the test duration, and preventing further substrate oxidation by steam. Interestingly, thin voids present in the as deposited coating self-heal by forming Cr rich oxides, which block steam to reach the substrate

    Límites en el uso de balances de exergía en los sistemas de cogeneración.

    Get PDF
    El balance exergético de un proceso de cogeneración de Fuerza Motriz (o Energía Eléctrica) y vapor para procesos industriales de calefacción (calentamiento, evaporación, cocimiento, destilación, etc), resulta útil cuando se trata de optimizar las instalaciones. No obstante, para evaluar los probables beneficios, es necesaria la comparación de los balances energéticos globales del proceso.\ud En este trabajo, se toman como ejemplos dos casos:\ud a) Análisis de las pérdidas de exergía debidas a la caída de presión en la tubería que conduce vapor desde la caldera hasta la turbina y la incidencia de la reducción de las mismas en las necesidades energéticas del sector de calefacción.\ud b) Análisis de un sistema de evaporación de múltiples efectos con extracciones de vapor para calefacción de jugo.\ud De este estudio se concluye que considerar solamente el balance exergético para valorar los beneficios de las modificaciones propuestas en estos casos, puede conducir a confusiones en la interpretación de los resultados o resultar un trabajo superfluo

    Long-term plasticity in growth, storage and defense allocation produces drought-tolerant juvenile shrubs of Prosopis alpataco R.A. Philippi (Fabaceae)

    Get PDF
    Evaluation of phenotypic plasticity of plants is important to predict the long-term fate of populations exposed to environmental change. Climate scenarios predict a decrease in rainfall and increase in temperature for Northern Patagonia (Argentina). The long-term assessment of the effect of water shortage on allocation patterns of . Prosopis alpataco provides insights into how climate change could affect this dominant shrub of the Monte Desert. A single-factor (water supply) field experiment was conducted. Phenotypic plasticity in biomass partitioning and allocation to storage and defense was assessed over the course of pre-reproductive growth during five years. Water-effect and size-dependent effects were sorted out. Our results indicate that as plants grow larger, root:shoot ratio increases, as well as total non-structural carbohydrates pool, irrespective of water treatment. Increasing belowground allocation through partitioning to reserves instead of allocation to non-storage mass, favors carbohydrate forms that later can be mobilized. Spine mass ratio increased 3-fold in response to drought. These conservative strategies might facilitate the persistence of . Prosopis alpataco in a novel and drier environment, through the production of drought-tolerant juvenile individuals.Fil: Vilela, Alejandra Elena. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Agüero, Paola R.. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Ravetta, Damián Andrés. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: González Paleo, Luciana. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    On the use of Hidden Markov Processes and auto-regressive filters to incorporate indoor bursty wireless channels into network simulation platforms

    Get PDF
    In this paper we thoroughly analyze two alternatives to replicate the bursty behavior that characterizes real indoor wireless channels within Network Simulation platforms. First, we study the performance of an improved Hidden Markov Process model, based on a time-wise configuration so as to decouple its operation from any particular traffic pattern. We compare it with the behavior of Bursty Error Model Based on an Auto-Regressive Filter, a previous proposal of ours that emulates the received Signal to Noise Ratio by means of an auto-regressive filter that captures the “memory” assessed in real measurements. We also study the performance of one of the legacy approaches intrinsically offered by most network simulation frameworks. By means of a thorough simulation campaign, we demonstrate that our two models are able to offer a much more realistic behavior, yet maintaining an affordable response in terms of computational complexity.The authors would like to express their gratitude to the Spanish government for its funding in the project “Connectivity as a Service: Access for the Internet of the Future”, COSAIF (TEC2012-38574-C02-01

    The Merging System Am 2049-691

    Get PDF
    Spectroscopic and photometric observations of the peculiar object AM 2049-691 are presented here. Its systemic velocity is V(GSR) = (10956 +-30) km/s, and the derived distance (H(0) = 75 km/s/Mpc) results 146 Mpc. A bridge is observed between two very distinct nuclei whose separation is about 10 kpc, as well as two tails that emerge from the extremes SW and NE of the main body and extend up to 41 and 58 kpc respectively. The spectral characteristics of the all observed zones are typical of H II regions of low excitation. The internal reddening is quit high, particularly in the NE nucleus. All the derived equivalent widths of the H(alpha)+[N II] lines indicate enhanced star formation compared with isolated galaxies, specially in the NE nucleus; the equivalent width corresponding to the integrated spectrum reflects starburst activity in the whole object, and is compatible with a merger of two disk galaxies. All the observed characteristics of AM 2049-691 indicate it is a merger, where a overabundance of nitrogen is detected in one of the nuclei, which has the most evolved population and would be the most massive one. The detected total IR emission is not very high. The integrated total color B - V corresponds to a Sc-Scd galaxy and its average integrated population is about F7 type. Indicative B - V colors of the nuclei, corrected for internal absorption, are in agreement with the spectroscopic results. The central radial velocity dispersions at the nuclei suggest that the most massive galaxy would be the progenitor of the SW component. The observed radial velocity curve shows the presence of two subsystems, each one associated with a different nucleus.Comment: 5 pages, 4 figure

    Hidden Trigger for the Giant Starburst Arc in M 83?

    Get PDF
    The huge star formation events that occur at some galactic centers do not provide enough clues as to their origin, since the morphological signatures of the triggering mechanism are smeared out in the timescale of a few orbital revolutions of the galaxy core. Our high spatial resolution three-dimensional near-infrared spectroscopy for the first time reveals that a previously known hidden mass concentration is located exactly at the youngest end of a giant star-forming arc. This location, the inferred average cluster ages, and the dynamical times clearly indicate that the interloper has left behind a spur of violent star formation in M 83, in a transient event lasting less than one orbital revolution. The study of the origin (bar funneling or cannibalized satellite) and fate (black hole merging or giant stellar cluster) of this system could provide clues to the question of core growing and morphological evolution in grand-design spiral galaxies. In particular, our TreeSPH numerical modeling suggests that the two nuclei could coalesce, forming a single massive core in about 60 million years or less

    Vacuum tribological behaviour of self lubricant quasicrystalline composite coatings

    Full text link
    High temperature resistant self-lubricant coatings are needed in space vehicles for components that operate at high temperatures and/or under vacuum. Thick composite lubricant coatings containing quasicrystalline alloys (QC) as the hard phase for wear resistance, have been deposited by thermal spray. The coatings also comprise lubricating materials (silver and BaF2-CaF2 eutectic) and NiCr as the tough component. This paper describes the vacuum tribological properties of TH103, a coating belonging to this family, with excellent microstructural quality. The coating was deposited by HVOF and tested under vacuum on a pin-on-disc tribometer. Different loads, linear speeds and pin materials were studied. The pin scars and disc wear tracks were characterized by EDS-SEM. A minimum mean steady friction coefficient of 0.32 was obtained employing a X-750 Ni superalloy pin in vacuum conditions under 10 N load and 15 cm/s linear speed, showing moderate wear of the disc and low wear of the pin

    The nuclear source of the galactic wind in NGC 253

    Get PDF
    We present Brγ emission line kinematics of the nuclear region of NGC 253, recently known to host a strong galactic wind that limits the global star formation of the galaxy. We obtained high-resolution long-slit spectroscopic data with PHOENIX at Gemini South, positioning the slit on the nucleus infrared core (IRC), close to the nuclear disk major axis. The spatial resolution was 0.″35 (∼6 pc) and the slit length was 14″ (∼240 pc). The spectral resolution was ∼74,000, unprecedentedly high for galactic nuclei observations at ∼2.1 μm. The line profiles appear highly complex, with blue asymmetry up to 3.″5 away of the IRC, and red asymmetries further away to northeast. Several Gaussian components are necessary to fit the profile, nevertheless a narrow and a wide one predominate. The IRC presents kinematic widths above 700 km s-1 (FWZI), and broad component FWHM ∼ 400 km s-1, the highest detected in a nearby galaxy. At the IRC, the blueshifted broad component displays a 90 km s-1 bump in radial velocity distribution, a feature we previously detected in molecular gas kinematics. The narrow component velocity dispersion (∼32 km s-1) is within the expected for normal galaxies and luminous infrared galaxies (LIRGs). Intermediate components (FWHM ∼ 150 km s-1, redshifted to the northeast, blueshifted to the southwest) appear at some positions, as well as weaker blue (-215 km s-1) and red line wings (+300 km s-1). The IRC depicts a large broad-versus-narrow line flux ratio (F(B)/F(N) ∼ 1.35), and the broad component seems only comparable with those observed at very high star-forming rate galaxies. The results indicate that the IRC would be the main source of the galactic winds originated in the central region of NGC 253.Fil: Gunthardt, Guillermo Ivan. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; ArgentinaFil: Díaz, R. J.. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; Argentina. Gemini Observatory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Agüero, Maria Paz. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Gimeno, G.. Gemini Observatory; Estados UnidosFil: Dottori, H.. Universidade Federal do Rio Grande do Sul; BrasilFil: Camperi, Javier Antonio. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Grupo de Medio Interest., Instument. y Galaxias; Argentin
    corecore