2,664 research outputs found

    Estimate of the willing to pay for ecological panela in Colombia: Approach from the Sustainable Consumption

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    Estimation of the environmental services values, represents a crucial element in the process of taking of decisions on environmental programs and policies to develop, as well as an orientation instrument for the implementation of production patterns and more sustainable consumption. From this perspective, the present study has as purpose to estimate the willing to pay (WTP) of the consumers from Bogota of ecological panela (product obtained from sugar canne in small rural factories). For this the method of Contingent Valuation was used. By means of selected stratified sampling a sample was determined by socioeconomic stratum for the city of Bogota the consumers were asked if they would be willing to pay for ecological panela, as well as topics related with their consumption behavior, like preferences, environmental, social commitment, and their socioeconomic characteristics. By means of the combination of this method of economic valuation and qualitative information this paper concluded that the consumers are willing to pay a bigger price for these panela types, especially for the powder ecological panela. A crucial conclusion is that, the existence of a direct relationship between the socioeconomic stratum and the WTP by conventional and ecological powder panela. Finally, it was determined that the commitment for the conservation and protection of the environment, when it is perceived by the consumer like an element that it guarantees the consumption of healthy and innocuous products, it represents a decisive factor in the willing to pay a bigger price for conventional and ecological powder panela.Ecological Panela, Contingent Valuation, Sustainable Consumption, Ecological Products.

    Experimental and analytical study to model temperature profiles and stoichiometry in oxygen-enriched in-situ combustion

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    A new combustion zone analytical model has been developed in which the combustion front temperature may be calculated. The model describes in the combustion zone, the amount of fuel burned based on reaction kinetics, the fuel concentration and produced gas composition based on combustion stoichiometry, and the amount of heat generated based on a heat balance. Six runs were performed in a 3-inch diameter, 40-inch long steel combustion tube with Jobo crude oil (9-11°API) from the Orinoco Belt in Venezuela. These runs were carried out with air containing three values of oxygen concentration, 21%, 30%, and 40%. The weight percentage of sand, clay, water, and oil in the sand mix was kept constant in all runs at 86.6%, 4.7%, 4.0%, and 4.7% respectively. Injection air rates (3 L/min) as well as the production pressure (300 psig) were kept constant in all runs. The results indicate that the calculated combustion zone temperatures and temperature profiles are in good agreement with the experimental data, for the range of oxygen concentration in the injected air. The use of oxygen-enriched air slightly increased the combustion front temperature from 440°C in a 21 mole % O2 concentration to a maximum of 475°C for air with 40 mole % O2 concentration. Oxygen-enriched air injection also increased the combustion front velocity from 13.4 cm/hr (for 21% oxygen) to 24.7 cm/hr (for 40% oxygen), thus reducing the start of oil production from 3.3 hours (for 21% oxygen) to 1.8 hours (for 40% oxygen). In the field, the use of oxygen-enriched air injection could translate into earlier oil production compared to with not-enriched air injection. The new analytical model for the combustion zone developed in this study will be beneficial to future researchers in understanding the effect of oxygen-enriched in-situ combustion and its implications on the combustion front temperature and combustion front thickness

    The Influence of Mental Imagery on Myofascial Restrictions

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    Mental imagery (MI) has been shown to influence flexibility when used with stretching. Currently, little evidence supports the efficacy of MI as an independent tool to increase flexibility. Therefore, the purpose of this investigation was to assess if a guided MI protocol could influence subject range of motion (ROM) measures. Thirty individuals with no history of lower limb injuries underwent initial measures, random group assignment, and post- intervention measures.The imagery group followed a guided visualization of a hamstring stretch, and the control group remained still for the same amount of time. No significant group by time differences were found between the two groups for any of the recorded measures. Although statistical significance was not demonstrated, a post hoc power analysis showed a small effect size on the ANOVA test for knee extension. This study shows that an acute MI-only protocol may not positively influence ROM measures in the hamstring musculature. Future work should use familiarization periods to determine if a learning effect is related to the efficacy of an MI protocol to influence flexibility and validated imagery assessment methods. Future work should also utilize different musculature and stretches to determine if visualization has a uniform influence globally and if different stretch variations may be more efficacious in influencing flexibility

    Prototipo de vivienda de adobe con energías renovables: caso de estudio localidad de Raíces, Área Natural Protegida del Parque Nacional del Nevado de Toluca, Estado de México

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    Como una alternativa a la construcción de la vivienda, este artículo introduce una nueva tecnología para edificar un prototipo de casa de adobe con energías renovables. Se muestrauna metodología para su diseño que se establece a partir de las características de las viviendas de la localidad de Raíces, ubicada en el municipio de Zinacantepec, dentro del territorio del Parque Nacional del Nevado de Toluca, espacio natural protegido por Decreto en 1936

    Increased amino acid turnover and myofibrillar protein breakdown in advanced cancer are associated with muscle weakness and impaired physical function

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    Muscle wasting in cancer negatively affects physical function and quality of life. This study investigates amino acid metabolism and the association with muscle mass and function in patients with cancer.In 16 patients with advanced cancer undergoing chemotherapy and 16 healthy controls, we administered an intravenous pulse and prime of stable amino acid tracers. We took blood samples to measure the Rate of appearance (Ra), whole body production (WBP), clearance (Cl), and post absorptive whole body net protein breakdown (WBnetPB). Plasma amino acid concentrations and enrichments were analysed by LC-MS/MS. We assessed muscle mass, handgrip/leg/respiratory muscle strength and reported physical activity, quality of life, and physical function.Muscle strength was lower in cancer patients than in healthy controls. Total and limb muscle mass, reported physical activity and WBnetPB were comparable. WBP and Cl of tau-methylhistidine, leucine, glutamine and taurine were higher in cancer patients as well as glycine Cl. Amino acid metabolism was correlated with low muscle mass, strength, physical function and quality of life.Myofibrillar protein breakdown and production of amino acids involved in muscle contractility are up regulated in patients with cancer undergoing chemotherapy and related to muscle weakness and reduced physical outcomes

    A constitutive model for analyzing martensite formation in austenitic steels deforming at high strain rates

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    This study presents a constitutive model for steels exhibiting SIMT, based on previous seminal works, and the corresponding methodology to estimate their parameters. The model includes temperature effects in the phase transformation kinetics, and in the softening of each solid phase through the use of a homogenization technique. The model was validated with experimental results of dynamic tensile tests on AISI 304 sheet steel specimens, and their predictions correlate well with the experimental evidence in terms of macroscopic stress–strain curves and martensite volume fraction formed at high strain rates. The work shows the value of considering temperature effects in the modeling of metastable austenitic steels submitted to impact conditions. Regarding most of the works reported in the literature on SIMT, modeling of the martensitic transformation at high strain rates is the distinctive feature of the present paper.The researchers of the University Carlos III of Madrid are indebted to the Comunidad Autónoma de Madrid (Project CCG10-UC3M/DPI-5596)) and to the Ministerio de Ciencia e Innovación de España (Project DPI/2008-06408) for the financial support received which allowed conducting part of this work. The authors express their thanks to Mr. Philippe and Mr. Tobisch from the company Zwick for the facilities provided to perform the tensile tests at high strain rates

    A constitutive model for analyzing martensite formation in austenitic steels deforming at high strain rates

    Get PDF
    This study presents a constitutive model for steels exhibiting SIMT, based on previous seminal works, and the corresponding methodology to estimate their parameters. The model includes temperature effects in the phase transformation kinetics, and in the softening of each solid phase through the use of a homogenization technique. The model was validated with experimental results of dynamic tensile tests on AISI 304 sheet steel specimens, and their predictions correlate well with the experimental evidence in terms of macroscopic stress–strain curves and martensite volume fraction formed at high strain rates. The work shows the value of considering temperature effects in the modeling of metastable austenitic steels submitted to impact conditions. Regarding most of the works reported in the literature on SIMT, modeling of the martensitic transformation at high strain rates is the distinctive feature of the present paper.The researchers of the University Carlos III of Madrid are indebted to the Comunidad Autónoma de Madrid (Project CCG10-UC3M/DPI-5596)) and to the Ministerio de Ciencia e Innovación de España (Project DPI/2008-06408) for the financial support received which allowed conducting part of this work. The authors express their thanks to Mr. Philippe and Mr. Tobisch from the company Zwick for the facilities provided to perform the tensile tests at high strain rates
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