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In this study, the food and nutritional energy requirements in Syria for the years of 2020,2030, 2040 and 2050 were calculated by assessing the demand and capacity of the country. The food requirement (ton/year) based on the various food sectors was calculated, which was used to determine the amount of food to feed Syria. For the enhancement of the food productivity, the shortcomings in the sector were identified. It was also aimed to provide a guidance on which basic steps should be taken during the rehabilitation period by assessing the agricultural and food self-sufficiency of Syria and help to develop a food policy for Syria’s future. According to the results, after the crisis/war in the future, the population of Syria will increase and reach to about 34 million in 2050. Syria will face with difficulties in feeding this expanding population, which is two-folds the current number. Additionally, climatic change will cause more arid region in Syria due to its geographical position, therefore it will depress the growth of food. Food security will also be another problem for Syria after the crisis/war.
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
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At high temperatures, isotope partitioning is often assumed to proceed under equilibrium and trends in the carbon isotope composition within graphite and diamond are used to deduce the redox state of their fluid source. However, kinetic isotope fractionation modifies fluid- or melt-precipitated mineral compositions when growth rates exceed rates of diffusive mixing. As carbon self-diffusion in graphite and diamond is exceptionally slow, this fractionation should be preserved. We have hence performed time series experiments that precipitate graphitic carbon through progressive oxidization of an initially CH4-dominated fluid. Stearic acid was thermally decomposed at 800 °C and 2 kbar, yielding a reduced COH-fluid together with elemental carbon. Progressive hydrogen loss from the capsule caused CH4 to dissociate with time and elemental carbon to continuously precipitate. The newly formed C0, aggregating in globules, is constantly depleted by -6.5±0.3‰ in 13C relative to the methane, which defines a temperature dependent kinetic graphite-methane 13C/12C fractionation factor. Equilibrium fractionation would instead yield graphite heavier than the methane. In dynamic environments, kinetic isotope fractionation may control the carbon isotope composition of graphite or diamond, and, extended to nitrogen, could explain the positive correlation of δ13C and δ15N sometimes observed in coherent diamond growth zones. 13C enrichment trends in diamonds are then consistent with reduced deep fluids oxidizing upon their rise into the subcontinental lithosphere, methane constituting the main source of carbon.,Earth and Planetary Science Letters, 529,
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
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Mathematical programming (MP) is a widespread approach to depict production and investment decisions of agents in agent-based models (ABM) related to agriculture. However, introducing dynamics and indivisibilities in MP models renders their solution computing time intensive. We present a meta-modeling approach as an alternative to directly integrating MP in an ABM. Specifically, we estimate a dual symmetric normalized quadratic (SNQ) value function from a set of MP solutions. The approach allows us to depict relationships between key attributes, like the farm endowment with (quasi-) fixed factors and discounted farm household incomes, without modeling the technology in detail. The estimated functions are integrated in the ABM to derive agents’ decisions. The meta-modeling approach relaxes computational restrictions such that spatial interactions in large regions can be simulated improving our understanding of structural change in agriculture. It can also be used to extrapolate to farming populations where data availability might be restricted.
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
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Contexte : En France, depuis le 1er novembre 2019, tous les restaurants scolaires distribuant plus de 200 repas par jour sont tenus de proposer au moins une fois par semaine un menu végétarien. La présente étude a été initiée et co-élaborée par les chercheurs et professionnels de la restauration scolaire du collectif EnScol. Méthodes : La composition nutritionnelle de plats complets (c’est-à-dire l’association plat protidique et accompagnement) a été étudiée, et comparée selon qu’ils étaient végétariens (n=315) ou non-végétariens (n=669). Au sein des plats complets végétariens, trois catégories ont été définies et comparées entre elles : plats sans aucun ingrédient d’origine animale, plats avec fromage, plats contenant des oeufs et/ou des produits laitiers autres que du fromage. Résultats : Les plats complets, qu’ils soient végétariens ou non-végétariens, affichent des teneurs convenables pour tous les nutriments protecteurs, à l’exception des acides gras oméga 3 (acide alpha-linolénique-ALA et acide docosahexaénoïque-DHA) et de la vitamine D, et (pour les plats non-végétariens uniquement) du calcium. Les trois catégories de plats complets végétariens affichent des teneurs convenables en plusieurs nutriments protecteurs (fibres, vitamines A, B1, B3, B6, B9, E, fer, magnésium, cuivre, iode, sélénium), chaque catégorie présentant ses propres caractéristiques nutritionnelles. Ainsi : - les plats sans aucun ingrédient d’origine animale contiennent beaucoup de fibres et peu d’acides gras saturés (AGS) mais ils présentent des teneurs faibles en vitamines B2 et B12, et ils manquent totalement de vitamine D et de DHA. Ils contiennent beaucoup de fer, mais c’est du fer non-héminique dont l’absorption est plus faible que le fer héminique d’origine animale. - les plats avec fromage sont ceux qui contiennent le plus de calcium mais ils ont davantage d’AGS que les deux autres catégories. - les plats contenant des oeufs et/ou des produits laitiers autres que du fromage ont des teneurs intermédiaires entre celles des plats des deux précédentes catégories pour la plupart des nutriments. Ils apparaissent comme un bon compromis, car ils apportent les nutriments essentiels associés aux oeufs et aux produits laitiers frais sans apporter les teneurs potentiellement élevées d’AGS et de sodium liées au fromage quand il est présent en quantité importante. Conclusion : il est nécessaire d’assurer un équilibre entre ingrédients d’origine végétale non raffinés (légumes, légumes secs, céréales complètes, …) et ingrédients d’origine animale (oeufs et produits laitiers) en quantité adaptée, dans l’élaboration des plats composant les menus végétariens en restauration scolaire. English abstract: Context: In France, since 1 November 2019, all school restaurants serving more than 200 meals a day are required to offer a vegetarian menu at least once a week. This study was initiated and co-developed by researchers and school catering professionals from the « EnScol » team. Methods: The nutritional content of main dishes (i.e. the combination of protein dish and side dish) was studied and compared according to whether the dishes were vegetarian (n=315) or non-vegetarian (n=669). Within the vegetarian main dishes, three categories were defined and compared: dishes without any ingredients of animal origin, dishes with cheese, and dishes containing eggs and/or dairy products other than cheese. Results: The main dishes, whether vegetarian or non-vegetarian, show adequate levels of all beneficial nutrients, with the exception of omega-3 fatty acids (alpha-linolenic acid-ALA and docosahexaenoic acid-DHA) and vitamin D, and (for non-vegetarian dishes only) calcium. The three categories of vegetarian main dishes have adequate levels of several beneficial nutrients (fibre, vitamins A, B1, B3, B6, B9, E, iron, magnesium, copper, iodine, selenium). However, each category displays its own nutritional characteristics: - dishes without any ingredients of animal origin contain a lot of fibre and few saturated fatty acids (SFA), but they are low in vitamins B2 and B12, and are totally lacking vitamin D and DHA. They contain a lot of iron, but it is non-heme iron that is less absorbed than heme iron of animal origin. - Dishes with cheese contain the highest content of calcium, but they have more SFA than the other two categories. - Dishes containing eggs and/or dairy products other than cheese display, for most beneficial nutrients, intermediate levels between the two previous categories. They appear to be a good compromise as they provide the essential nutrients associated with eggs and fresh dairy products without providing the potentially high levels of SFA and sodium associated with cheese when it is present in too high amounts. Conclusion: It is necessary to ensure a balance between unrefined plant-based ingredients (vegetables, pulses, whole grains, etc.) and animal-based ingredients (eggs and dairy products) in appropriate quantities when preparing vegetarian dishes for school meals.
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