3,907 research outputs found

    Implications of the U.S. Farm Act on Canadian Agriculture

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    This paper addresses the implications of the U.S. Farm Security and Rural Investment Act of 2002 or "Farm Act" for Canadian agriculture. The Farm Act, which is expected to add at least US $45 billion in new price supports over its six-year timeframe, is expected to harm the position of less-subsidized and non-subsidized producers in Canada and other countries. Canadian farm products will be less competitive not only domestically, but also in the U.S. and in third-country markets. Canada will be most affected by subsidies for corn, soybeans, wheat, and pulse crops. New country-of-origin labeling rules under the Farm Act are also expected to be disruptive to Canadian livestock exports. In addressing these issues the paper also explores potential Canadian responses - including filing WTO or NAFTA complaints - as well as the broader implications for U.S.-Canada trade and international cooperation.U.S. Farm Bill, U.S.-Canada trade, Agricultural and Food Policy, International Relations/Trade,

    Underlying inflation in the spanish economy: estimation and methodology

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    This paper presents a methodology to analyse the inflationary process in Spain. It is based on forecasts of the Consumer Price Index using quantitative models to obtain a measure of underlying inflation and the expected medium-term value of the annual price growth rate, which is called inertia in the paper. Every time a new observation becomes available, the study of the underlying inflation and inertia allows to be performed a systematic analysis of the inflationary process. The estimation of underlying inflation and inertia has also proven useful to improve the measurement of some important economic indicators such as inflation differentials and ex-ante real interest rates

    Clinkering and hydration study of non-active and active Belite-Alite-Ye'elimite (BAY) cements

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    The aim of AIM is to promote industry-driven, interdisciplinary research in material science and engineering in order to provide leading-edge, sustainable solutions to the challenges facing engineers in today’s changing society and environment. http://www.ucl.ac.uk/aim/conference-info/37ccsThe manufacturing process of ye'elimite rich cements emit about 15-37% less CO2 to the atmosphere than OPC. Cements that contain belite, ye’elimite and ferrite, known as BYF cements, are promising eco-friendly binders. However, belite, their main phase, shows a slow hydrating behaviour; therefore the corresponding mortars present lower mechanical strengths than OPC at early ages. To solve this problem, BYF clinkers can be activated by: i) forming alite jointly with belite and ye’elimite during clinkering, known as BAY clinkers. The alite and ye’elimite reaction with water should develop high mechanical strengths at early ages, besides, belite contributes to later curing times. ii) A second activation is based on the stabilisation of alpha forms of belite by dopants. The objective of this work is to obtain two types of BAY clinkers (standard and active BAY) using CaF2 as mineraliser and borax as dopant agent to stabilize alpha forms of belite phase. After that, anhydrite was added as sulphate source to obtain the corresponding cements. The hydration behaviour of these cements has been studied through rheological and x-ray diffraction measurements, the latter combined with Rietveld quantitative phase analysis. In addition, mechanical and dimensional properties of BAY mortars are also presented and discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Advanced synchrotron studies of ye'elimite-based cement pastes

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    Synchrotron characterization techniques [1] are being used to study Portland-based cements and recently also CSA and related cements. A key property of these techniques is that they do not require sample preparation, so the microstructures of the pastes can be preserved. The classical application of synchrotron tools is powder diffraction used to determine the crystalline phase content evolution with hydration including the overall amorphous fraction. Furthermore, other most advanced techniques are being applied to ye'elimite-containing pastes such as i) Total Scattering Synchrotron Powder Diffraction (TS-SXPD), and ii) Ptychographic Synchrotron X-ray Computed Tomography (PSXCT). All these applications will be reviewed here. TS-SXPD data coupled with the Pair Distribution Function (PDF) analysis methodology [2] allows having a better insight about the nanocrystalline/amorphous atomic arrangements in the gels. It has been very recently shown that nanogibbsite with very small particles, 3nm, is the main constituent of ye'elimite-gypsum hydration paste [2]. Nanogibbsite particles being smaller than those originated from the hydration of monocalcium aluminate. In addition, PSXCT is a tomographic technique that profits from the partly coherent nature of the synchrotron beam to provide better (smaller) resolution, which can be lower than 100 nm. It also provides the mass densities if the chemical stoichiometries are known. This technique has been applied to ye'elimite hydration to determine the microstructure and chiefly the bulk densities of nanogibbsite [3]. The microstructure evolution at early age was also followed [4]. Figure 1 shows an example of a slide of the electron density tomogram for a ye'elimite paste at 8 days of hydration and the corresponding histogram for the full volume with all phases identified.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.This work has been supported by Spanish MINECO through BIA2014-57658-C2 and BIA2017-82391-R, which are co-funded by FEDER

    Diversity and biological aspects of wild bees in an urban and a natural environment in the central region of Santa Fe, Argentina

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    El objetivo del presente trabajo fue relevar el elenco de abejas silvestres en la región central de Santa Fe y comparar la diversidad de especies y aspectos biológicos en dos ambientes de una misma región. Las abejas fueron colectadas en el estrato herbáceo de la Reserva Universitaria “Escuela Granja” de la localidad Esperanza, y en la zona urbana de la localidad Susana, ambas ubicadas dentro de la Provincia Fitogeográfica del Espinal. La colecta se realizó en octubre, noviembre y diciembre de 2004 y en enero, febrero y marzo de 2005, registrando las especies vegetales sobre las que se capturaron. Se colectaron 277 ejemplares en total, de los cuales se identificaron 62 especies (27 géneros en 5 familias). Las curvas de rarefacción indican una tasa de acumulación de especies mayor para la Reserva Ecológica, los índices de diversidad de Shannon son 3,25 para la Reserva Ecológica y 2,64 para la Zona Urbana. Para la comparación de las comunidades en ambos sitios, las abejas fueron clasificadas en tres categorías según la especialización en el uso del recurso floral, sustrato de nidificación y comportamiento social. Se observó una asociación entre los grupos especialistas y de nidificación en el suelo con el ambiente natural, y por otro lado, las especies generalistas y de nidificación en cavidades con el ambiente urbano. No se identificaron diferencias, en cuanto al tipo de comportamiento social de las especies, entre ambos sitios.The purpose of this contribution is to present a survey of wild bees in the central region of Santa Fe, and to compare the diversity and biological aspects of the bee communities at two different environments of the same region. Bees were surveyed at the ecological reserve Reserva Universitaria “Escuela Granja” in the locality of Esperanza, and at an urban area in the locality of Susana, both in the Espinal Phytogeographic Province. Bees were sampled from October to December 2004 and from January to March 2005, recording their plant associations. A total of 277 specimens were collected, belonging to 62 species (27 genera in 5 families). The rarefaction curves indicate a higher rate of species accumulation for the ecological reserve; the Shannon diversity index was 3.25 for the ecological reserve and 2.64 for the urban area. In order to compare the composition of the bee communities at the two sites, the bees were classified into three categories: degree of specialization in the use of floral resources, nesting substrate, and social behavior. It was observed that specialized bees who nest in the soil showed an association with the natural environment while the generalist species who nest in pre-existing cavities showed an association with the urban environment. No association was found between type of social behavior and type of environment.Fil: Dalmazzo, Maria de Los Milagros. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin

    Applications of synchrotron x-ray powder diffraction in hydrated cements: high-resolution and high-pressure studies

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    The main aim of this study is to apply synchrotron radiation techniques for the study of hydrated cement pastes. In particular, the tetracalcium aluminoferrite phase, C4AF in cement nomenclature, is the major iron-containing phase in Ordinary Portland Cement (OPC) and in iron rich belite calcium sulfoaluminate cements. In a first study, the hydration mechanism of pure tetracalcium aluminoferrite phase with water-to-solid ratio of 1.0 has been investigated by HR-SXRPD (high resolution synchrotron X-ray powder diffraction). C4AF in the presence of water hydrates to form mainly an iron-containing hydrogarnet-type (katoite) phase, C3A0.84F0.16H6, as single crystalline phase. Its crystal structure and stoichiometry were determined by the Rietveld method and the final disagreement factors were RWP=8.1% and RF=4.8% [1]. As the iron content in the product is lower than that in C4AF, it is assumed that part of the iron also goes to an amorphous iron rich gel, like the hydrated alumina-type gel, as hydration proceeds. Further results from the high-resolution study will be discussed. In a second study, the behavior of pure and iron-containing katoites (C3AH6 and C3A0.84F0.16H6) under pressure have been analyzed by SXRPD using a diamond anvil cell (DAC) and then their bulk moduli were determined. The role of the pressure transmitting medium (PTM) has also been studied. In this case, silicone oil as well as methanol/ethanol mixtures have been used as PTM. Some “new peaks” were detected in the pattern for C3A0.84F0.16H6 as pressure increases, when using ethanol/methanol as PTM. These new peaks were still present at ambient pressure after releasing the applied pressure. They may correspond to crystalline nordstrandite or doyleite from the crystallization of amorphous aluminium hydroxide. The results from the high-pressure study will also be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Acknowledgments: We thank CELLS-ALBA (Barcelona, Spain) for providing synchrotron beam time. We also thank the financial support by BIA2014-57658-C2-1-R and BIA2014-57658-C2-2-R (FEDER)
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