168 research outputs found

    Taxation and Income Distribution Dynamics in a Neoclassical Growth Model

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    We examine how changes in tax policies affect the dynamics of the distributions of wealth and income in a Ramsey model in which agents differ in their initial capital endowment. The endogeneity of the labor supply plays a crucial role in determining inequality, as tax changes that affect hours of work will affect the distribution of wealth and income, reinforcing or offsetting the direct redistributive impact of taxes. Our results indicate that tax policies that reduce the labor supply are associated with lower output but also with a more equal distribution of after-tax income. We illustrate these effects by examining the impact of recent tax changes observed in the US and in European economies.taxation; wealth distribution; income distribution; endogenous labor supply; transitional dynamics

    Metal hydrides for hydrogen storage at low charging pressures

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    LaNi5 alloys are been extensively study as hydrogen storage material due their easy activation and good kinetics. LaNi5 alloys, containing substitutional elements such as Al or Ce, allow adjustments of the equilibrium pressure and absorption kinetics of the metallic hydrides making them storage candidate materials susceptible to be used in fuel cells systems. In this work, the thermodynamic properties of LaNi5-yAly and LaNi5, La1-xCexNi5 alloys were evaluated using a purpose built Sievert-type apparatus

    Optimizacion of planform and cruise conditions of a transport flying wing

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    The flying wing is a promising concept for the mid long-term commercial aviation. After the previously published conceptual design of a 300-seat class flying wing, the present article carries out a parametric analysis to optimize its planform and analyse the suitable cruise conditions to achieve the highest efficiency of such configuration. The figures of merit chosen for the optimization are the direct operating cost and the maximum take-off weight per passenger, for a specified constant range of 10 000 km. The design has to respect five relevant constraints: wingspan (limited to 80 m), cabin width, wing tip chord, number of passengers, and cruise lift coefficient. The optimum aircraft fulfilling all constraints cruises at 45 000–47 000 ft and M = 0.82, has an aspect ratio of 6.3 and taper ratio of 0.10, and carries about 280 passengers in three-class seating. This aircraft is about 20 per cent more efficient than conventional wide bodies of similar size, in terms of trip fuel

    Experimental analysis of a coiled stirred tank containing a low cost PCM emulsion as a thermal energy storage system

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    This article presents the results of heat transfer coefficient and volumetric energy density measurements in an agitated tank containing a low-cost phase change material emulsion, heated by water flowing in a coil. For the stirring a three-stage impeller is placed in the central axis of a 46 l commercial tank. By measuring the temperature dependency on time and solving the transient enthalpy balance, the heat transfer coefficient between the helical coil and the agitated phase change material emulsion is determined, based on the impeller Reynolds number. The thermal energy storage efficiency has also been analysed. This phase change material emulsion shows a phase change temperature range between 30 and 50 °C. Its solid content is about 60% with an average size of 1 µm. The results have shown that the overall heat transfer coefficient is around 3.5–5.5 times higher when a stirring rate of 290–600 rpm is used. Furthermore, even at the lowest stirring rate, the thermal energy storage efficiency improves from 76-77%–100%, without detriment to the energy consumption of the stirrer

    Hydroponics as a valid tool to assess arsenic availability in mine soils

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    The low solubility of As in mine soils limits its phytoavailability. This makes the extrapolation of data obtained under hydroponic conditions unrealistic because the concentration in nutrient solution frequently overexposes plants to this metalloid. This work evaluates whether As supply in hydroponics resembles, to some extent, the As phytoavailable fraction in soils and the implications for phytoremediation. Phytotoxicity of As, in terms of biomass production, chlorophyll levels, and As concentrations in plants, was estimated and compared in both soils and hydroponics. In order for hydroponic conditions to be compared to soil conditions, plant exposure levels were measured in both cultures. Hydroponic As concentration ranging from 2-8 ÎĽM equated to the same plant organ concentrations from soils with 700-3000 mg kg-1. Total and extractable As fractions exceeded those values, but As concentrations in pore water were bellow them. According to our results (i) hydroponics should include doses in the range 0-10 ÎĽM As to allow the extrapolation of the results to As-polluted soils, and (ii) phytoextraction of As in mining sites will be limited by low As phytoavailabilityThis study was supported by the Spanish Ministry of Education and Science, project CTM 2007-66401-CO2/TECNO, and by Comunidad de Madrid, project S-0505/AMB/029

    Differential diagnosis of infectious skin lesions in an HIV-positive patient: a case report

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    HIV infection makes HIV carriers susceptible to develop a group of infections that would not normally be found in an immunocompetent patient. In Colombia, a total of 11,606 cases of HIV infection were reported in 2015. This paper documents the case of a patient diagnosed with HIV infection, who developed lesions typically caused by the varicellazoster virus. These vesicular lesions evolved into phlyctenas with local necrosis. Given the case presentation, the diagnosis of skin lesions in immunocompromised or HIV-infected patients becomes a challenge for health professionals when determining an etiological diagnosis, in order to establish an appropriate treatment

    Gaia Early Data Release 3: The astrometric solution

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    [Context] Gaia Early Data Release 3 (Gaia EDR3) contains results for 1.812 billion sources in the magnitude range G = 3-21 based on observations collected by the European Space Agency Gaia satellite during the first 34 months of its operational phase. [Aims] We describe the input data, the models, and the processing used for the astrometric content of Gaia EDR3, as well as the validation of these results performed within the astrometry task. [Methods] The processing broadly followed the same procedures as for Gaia DR2, but with significant improvements to the modelling of observations. For the first time in the Gaia data processing, colour-dependent calibrations of the line- and point-spread functions have been used for sources with well-determined colours from DR2. In the astrometric processing these sources obtained five-parameter solutions, whereas other sources were processed using a special calibration that allowed a pseudocolour to be estimated as the sixth astrometric parameter. Compared with DR2, the astrometric calibration models have been extended, and the spin-related distortion model includes a self-consistent determination of basic-angle variations, improving the global parallax zero point. [Results] Gaia EDR3 gives full astrometric data (positions at epoch J2016.0, parallaxes, and proper motions) for 1.468 billion sources (585 millionwith five-parameter solutions, 882 million with six parameters), and mean positions at J2016.0 for an additional 344 million.Solutions with five parameters are generally more accurate than six-parameter solutions, and are available for 93% of the sources brighter than the 17th magnitude. The median uncertainty in parallax and annual proper motion is 0.02-0.03 mas at magnitude G = 9-14, and around 0.5 mas at G = 20. Extensive characterisation of the statistical properties of the solutions is provided, including the estimated angular power spectrum of parallax bias from the quasars.This work was financially supported by the European Space Agency (ESA) in the framework of the Gaia project; the German Aerospace Agency (Deutsches Zentrum für Luft- und Raumfahrt e.V., DLR) through grants 50QG0501, 50QG0601, 50QG0901, 50QG1401 and 50QG1402; the Spanish Ministry of Economy (MINECO/FEDER, UE) through grants ESP2016-80079-C2-1-R, RTI2018-095076-B-C21 and the Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia “María de Maeztu”) through grants MDM-2014-0369 and CEX2019-000918-M; the Swedish National Space Agency (SNSA/Rymdstyrelsen); and the United Kingdom Particle Physics and Astronomy Research Council (PPARC), the United Kingdom Science and Technology Facilities Council (STFC), and the United Kingdom Space Agency (UKSA) through the following grants to the University of Bristol, the University of Cambridge, the University of Edinburgh, the University of Leicester, the Mullard Space Sciences Laboratory of University College London, and the United Kingdom Rutherford Appleton Laboratory (RAL): PP/D006511/1, PP/D006546/1, PP/D006570/1, ST/I000852/1, ST/J005045/1, ST/K00056X/1, ST/K000209/1, ST/K000756/1, ST/L006561/1, ST/N000595/1, ST/N000641/1, ST/N000978/1, ST/N001117/1, ST/S000089/1, ST/S000976/1, ST/S001123/1, ST/S001948/1, ST/S002103/1, and ST/V000969/1

    Performance characterization of a PCM storage tank

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    This paper presents the experimental results of a versatile latent heat storage tank capable of working with organic phase-change materials within a temperature range from -10 °C to 100 °C. The tank contains a paraffin with a phase-change temperature between 3 °C and 8 °C. Firstly, this study focuses on explaining the design criteria which were followed to build the tank. Secondly, a full experimental characterization of the performance has been carried out. The enthalpy temperature curve, the specific heat and density have been measured for the tested paraffin. The performance of the tank has been analyzed in terms of the vertical stratification within the PCM, the effectiveness, the reacted fraction and the total heat transfer of the tank. The results indicate that up to 78% of the maximum capacity is reached within 4 h. The performance is mainly controlled by the supply temperature and the effect of the mass flow rate is almost negligible given that all the tests are in laminar flow.The authors from the Polytechnic University of Valencia gratefully acknowledge ACCIONA Infraestructuras for the funding of the LHTS installation. The authors from University of Zaragoza would like to thank the Spanish Government for the partial funding of this work within the framework of research projects ENE2008-06687-C02-02 and ENE2011-28269-C03-01.López Navarro, A.; Biosca Taronger, J.; Corberán Salvador, JM.; Peñalosa, C.; Lázaro, A.; Dolado, P.; Payá Herrero, J. (2014). Performance characterization of a PCM storage tank. Applied Energy. 119:151-162. doi:10.1016/j.apenergy.2013.12.041S15116211

    Conjugated probiotics dispensed from birth to weaning for the survival of goat kids

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    a) Objective: To prevent morbidities, mortalities and increase weight gain and growth of kids by administering oral probiotic conjugate (PC). b) Design/Methodology/Approach: A randomized design comparing treatments (supplemented dose), percentage of morbidity and percentage of mortality. Goats were administered weekly from birth to 56 days of age. PC of Bifidobacterium bifidum essensis, Lactococcus lactis, Streptococcus thermophilus and Lactobacillus bulgaricus were dosed weekly. Treatments, TC: Control, T2: 2.0 mL PC/kg body weight (BW). T3: 3 mL PC/Kg BW. T4: 4 mL PC/Kg BW. c) Results: Diarrhea was present in: TC = 16%, T2 = 1%, T3 and T4 = 0% (TC vs. T2, T3, T4, P <0.05). Mortality percentages: TC = 17%, T2, T3 and T4 = 0% (TC vs. T2, T3, T4, P <0.05). T2 and T3 had an increase (P <0.05) of 1.9 kg weight gain (WG) vs. TC. T3 was the best treatment at 56d (P <0.05). d) Study Limitations/Implications: The doses used were defined based on other studies and experimental doses were used; the results consider that the facilities and management are optimal and in accordance with animal welfare standards. e) Findings/Conclusions: The most adequate dose was 1014 CFU/kg BW since it improved WG and reduced mortality. It is suggested to compare oral doses of probiotics to reduce death due to enteric diseases.To prevent morbidities, mortalities and increase weight gain and growth of kids by administering oral probiotic conjugate (PC). Design/Methodology/Approach: A randomized design comparing treatments (supplemented dose), percentage of morbidity and percentage of mortality.  Goats were administered weekly from birth to 56 days of age. PC of Bifidobacterium bifidum essensis, Lactococcus lactis, Streptococcus thermophilus and Lactobacillus bulgaricus were dosed weekly. Treatments, TC: Control, T2: 2.0 mL PC/kg body weight (BW). T3: 3 mL PC/Kg BW. T4: 4 mL PC/Kg BW. Results: Diarrhea was present in: TC = 16%, T2 = 1%, T3 and T4 = 0% (TC vs. T2, T3, T4, P <0.05). Mortality percentages: TC = 17%, T2, T3 and T4 = 0% (TC vs. T2, T3, T4, P <0.05). T2 and T3 had an increase (P <0.05) of 1.9 kg weight gain (WG) vs. TC. T3 was the best treatment at 56d (P <0.05). Study Limitations/Implications: The doses used were defined based on other studies and experimental doses were used; the results consider that the facilities and management are optimal and in accordance with animal welfare standards. Findings/Conclusions: The most adequate dose was 1014 CFU/kg BW since it improved WG and reduced mortality. It is suggested to compare oral doses of probiotics to reduce death due to enteric diseases
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