Дисертації з теми "DDA modélisation"
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Alves, Alves Estefania. "Émission de photons dans un microscope à effet tunnel : application à l'étude des propriétés optiques et électroniques de systèmes hybrides métal-semi-conducteur." Electronic Thesis or Diss., Toulouse 3, 2023. http://www.theses.fr/2023TOU30351.
Transition metal dichalcogenides (TMDs) are a family of semiconductors that exhibit a direct bandgap when their thickness is reduced to a monolayer, giving them remarkable optical and electronic properties, including high-efficiency luminescence. Photon emission from these monolayers is investigated using the STM-LE (Light Emission induced by Scanning Tunneling Microscopy) technique. This innovative method involves the localized injection of charge carriers into TMD monolayers through the tunneling current. This process results in the formation of excitons, electron-hole pairs bound by Coulomb forces, within the TMD monolayer. These excitons decay radiatively emitting photons whose energy corresponds to the direct bandgap of the semiconductor. This light emission process is experimentally studied using an STM microscope combined with a light detection system, enabling spectral and spatial analysis of the photon emission with nanometer-scale resolution. The electromagnetic interaction between TMD layers and their metallic substrates leads to the formation of hybrid metal-semiconductor structures, the optical and electronic properties of which are under investigation. The nature of the substrate (plasmonic or non-plasmonic) and its morphology (uniform or nanostructured) play a crucial role in both the intensity and spectral distribution of the emitted photons. Indeed, for plasmonic substrates, the photon emission process involves the electromagnetic coupling between plasmon modes excited by electron tunneling and excitons confined within the TMD monolayer. This interaction leads to an enhancement of the photon emission. Moreover, by tuning the morphology of the substrate, it becomes possible to modify this coupling and thus, the photon emission rate. Considering the significant role of the electromagnetic interaction between plasmon modes and excitons in the luminescence from TMD monolayers within a hybrid TMD/metal-plasmonic STM junction, electromagnetic numerical simulations are carried out using the DDA (Discrete Dipole Approximation) method. These simulations account for electron tunneling using the Quantum Corrected Model. By simulating the optical response of the junction to an incident excitation wave, the electromagnetic modes within the junction and their dependence on the tunneling parameters, such as tip-surface distance and bias voltage, are investigated. In particular, gap plasmon modes and the Fano-type plasmon-exciton coupling at the interface between the monolayer and the plasmon substrate are pointed out. Furthermore, the role of substrate morphology on the properties of these modes is also addressed. Based on theoretical models describing the light emission taking place in purely metallic STM junctions proposed in the literature, a model is developed to compute theoretical light emission spectra for a hybrid TMD/plasmonic-metal STM junction. This model takes into account the optical and electronic properties of the TMD monolayer, and the electron tunneling as the excitation source at the origin of the light emission phenomenon. In addition, using the results obtained from the numerical simulations, the electromagnetic coupling between the excitons confined in the TMD monolayer and the plasmons excited in the nanocavity formed by the tip-surface configuration of the STM is also considered. Finally, the effect of the substrate morphology on the light emission is studied theoretically. These results are compared with the experimental findings in order to validate the model presented
Garcia, Fernandez Carlos. "Modeling Optical Properties of Combustion Soot emitted in the Troposphere." Thesis, Besançon, 2015. http://www.theses.fr/2015BESA2040/document.
This work concerns the modeling, at the molecular level, of the interaction between carbonaceous particles of nanometric size and the electromagnetic radiation. The goal is to improve our understanding of the optical properties of soot particles, to better quantify the influence of soot on the atmosphere and on climate change. The study of the interaction between radiation and fresh soot particles was carried out using the point dipole interaction method; it has been shown that: i) the mass absorption coefficient (MAC) of these soot nanoparticles may significantly depend on their atomistic details, especially between 200 and 350 nm; ii) the MAC depends on whether the heart of the carbonaceous particle is occupied or not by graphite planes; iii) an analytical model is not suitable for calculating the MAC of carbonaceous nanoparticles having structural defects. In addition, quantum chemical methods have been used to characterize the ageing of soot. The results obtained are i) NO, Cl, and HCl are physisorbed on a perfect carbonaceous surface whereas on a defective surface, these species are chemisorbed and lead to a modification of the surface; ii) on a carbonaceous surface, the presence of adsorbed Cl atoms leads to a strong trapping of the surrounding water molecules. This may be related to the highly hydrophilic nature of soot emitted during fires in industrial environments. Finally, the PDI method was applied to calculate the polarizability of PAHs to help at interpreting the absorption spectra of carbonaceous grains in the interstellar medium, including molecules for which no data was currently available
Thiao, Mamadou. "Approches de la programmation DC et DCA en data mining : modélisation parcimonieuse de données." Phd thesis, INSA de Rouen, 2011. http://tel.archives-ouvertes.fr/tel-00667179.
Trépanier, Diego. "Modélisation de la dynamique d'un manipulateur sériel plan à 2 ddl submergé dans un fluide." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/26753/26753.pdf.
Tran, Van Nam. "Adsorption statique de PCB et de DDT sur charbons actifs en milieux aqueux." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10301.
The solid-liquid adsorption of PCBs and DDT is an effective process for the recuperation of wastewaters but a better understanding of the involved mechanism is required. In this study, the static adsorption kinetics were mainly carried out at 25 ° C for 2-PCB, a mixture of tetra-, penta-and hexa-CB, and 4,4 '-DDT onto three different powdered activated carbons (AC) of the precursor (coal, wood) and the activation mode (H2O, H3PO4) in water, with or without ethanol. The prominent results were as follows: The adsorption of the pollutant on the AC is favored if its solubility in the liquid phase is lower. As a result, the adsorption of the hydrophobic pollutant is significantly increased in pure water. Moreover, the adsorption of pollutants favored by the developed microporosity is a surface phenomenon which involved the Van der Waals forces. A good fit between the size of molecules and the average width of the slit-shape pores gave a maximum confinement of molecules in the micropores. The π−π interaction between adsorbate and adsorbent, favored by the number of Cl, is not excluded. Finally, by studying the kinetics of the initial conditions, we found that the adsorption is limited by the external mass transfer. The internal surface diffusion coefficients estimated from applying the homogeneous surface diffusion models (HSDM) showed that the adsorption kinetics are almost completely governed by the intra-particle diffusion
Sakami, Siham. "Modélisation numérique des structures composites multicouches à l’aide d’une approche discrète au sens de Mindlin. Le modèle DDM (Displacement Discrete Mindlin)." Reims, 2008. http://theses.univ-reims.fr/exl-doc/GED00000982.pdf.
The present work of the thesis deals with the theoretical formulation and the evaluation of a new first order finite element for multilayered/sandwich plates and shells. It’s based on a displacement variational model that we consider as discrete, insofar as we introduce kinematic and mechanical hypothesises in a discrete manner. This model, labelled DDM (Discrete Displacement Mindlin), leads to a finite element which is geometrically simple (4 node) and efficient, owing to the linearity of bending curvatures obtained from a quadratic approximation of the normal rotations to the plate mid-surface. The new element takes into account the transverse shear effects along thickness direction and gives thin plate results when the ratio L/h (Length/ thickness) becomes big. It has been successfully validated across some known testing problems, from thin to thick laminated and sandwich
Bédard, Sébastien. "Modélisation et simulation dynamique d'un bipède plan à 9 DDL : à titre de recherche préliminaire pour le développement d'un robot bipède anthropomorphe." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/24083/24083.pdf.
Le, Hoai Minh. "Modélisation et optimisation non convexe basées sur la programmation DC et DCA pour la résolution de certaines classes des problèmes en fouille de données et cryptologie." Thesis, Metz, 2007. http://www.theses.fr/2007METZ054S/document.
This thesis is dedicated to non-convex modeling and the optimization based on the DC programming and DCA for certain classes of problems of two important domains : the Data Mining and the Cryptology. They are non-convex optimization problems of very large dimensions for which the research of good solution methods is always of actuality. Our work is based mainly on the DC programming and DCA that have been successfully applied in various fields of applied sciences, including machine learning. It is motivated and justified by the robustness and the good performance of DC programming and DCA in comparison with the existing methods. This thesis is devised in three parties. The first part, entitling Methodology, serves as a reference for other chapters. The first chapter concerns the programming of DC and DCA while the second chapter describes the genetic algorithms. In the second part, we develop the DC and DCA programming to solve two classes of problems in Data Mining. In the chapter four, we take consideration into the model of classification FCM and develop the programming DC and DCA for their resolution. Many formulations DC in correspondence to different decompositions DC are proposed. Our work in hierarchic classification (chapter 5) is motivated by one of its interesting and very important applications, known as muliticast communication. It's a non-convex, non differentiable, non-convex problem in a very big dimension with which we have reformulated in the forms of 3 different DC programs and developed the DCA relative. The 3rd part focuses on the Cryptology. The 1st chapter is the construction of stable boonlean functions with high degree of non-linearity - one of the crucial problems of Cryptography. Many versions of combination of 2 approaches, DCA and Genetic Algorithms (GA) are studied in the purpose of exploiting simultaneously the efficacy of each approach. The secondrd work is about the techinics of cryptanalyse of a identification scheme based on two problems Perceptron (PP) and Perceptron Permuted. We propose a method of resolving two problems PP and PPA by DCA and a cutting plan method in the last chapter
Le, Hoai Minh. "Modélisation et optimisation non convexe basées sur la programmation DC et DCA pour la résolution de certaines classes des problèmes en fouille de données et cryptologie." Electronic Thesis or Diss., Metz, 2007. http://www.theses.fr/2007METZ054S.
This thesis is dedicated to non-convex modeling and the optimization based on the DC programming and DCA for certain classes of problems of two important domains : the Data Mining and the Cryptology. They are non-convex optimization problems of very large dimensions for which the research of good solution methods is always of actuality. Our work is based mainly on the DC programming and DCA that have been successfully applied in various fields of applied sciences, including machine learning. It is motivated and justified by the robustness and the good performance of DC programming and DCA in comparison with the existing methods. This thesis is devised in three parties. The first part, entitling Methodology, serves as a reference for other chapters. The first chapter concerns the programming of DC and DCA while the second chapter describes the genetic algorithms. In the second part, we develop the DC and DCA programming to solve two classes of problems in Data Mining. In the chapter four, we take consideration into the model of classification FCM and develop the programming DC and DCA for their resolution. Many formulations DC in correspondence to different decompositions DC are proposed. Our work in hierarchic classification (chapter 5) is motivated by one of its interesting and very important applications, known as muliticast communication. It's a non-convex, non differentiable, non-convex problem in a very big dimension with which we have reformulated in the forms of 3 different DC programs and developed the DCA relative. The 3rd part focuses on the Cryptology. The 1st chapter is the construction of stable boonlean functions with high degree of non-linearity - one of the crucial problems of Cryptography. Many versions of combination of 2 approaches, DCA and Genetic Algorithms (GA) are studied in the purpose of exploiting simultaneously the efficacy of each approach. The secondrd work is about the techinics of cryptanalyse of a identification scheme based on two problems Perceptron (PP) and Perceptron Permuted. We propose a method of resolving two problems PP and PPA by DCA and a cutting plan method in the last chapter
Belghiti, Moulay Tayeb. "Modélisation et techniques d'optimisation en bio-informatique et fouille de données." Thesis, Rouen, INSA, 2008. http://www.theses.fr/2008ISAM0002.
This Ph.D. thesis is particularly intended to treat two types of problems : clustering and the multiple alignment of sequence. Our objective is to solve efficiently these global problems and to test DC Programming approach and DCA on real datasets. The thesis is divided into three parts : the first part is devoted to the new approaches of nonconvex optimization-global optimization. We present it a study in depth of the algorithm which is used in this thesis, namely the programming DC and the algorithm DC ( DCA). In the second part, we will model the problem clustering in three nonconvex subproblems. The first two subproblems are distinguished compared to the choice from the norm used, (clustering via norm 1 and 2). The third subproblem uses the method of the kernel, (clustering via the method of the kernel). The third part will be devoted to bioinformatics, one goes this focused on the modeling and the resolution of two subproblems : the multiple alignment of sequence and the alignment of sequence of RNA. All the chapters except the first end in numerical tests
Sezgin, Jean-Gabriel. "Modélisation de la formation des décohésions dues à l’hydrogène dans l’acier 18MND5." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEM006/document.
Heat generators are manufactured from ingots of 18MND5 (A508cl3) low alloy steel and present composition heterogeneities at different scales. Under specific conditions (non-respect of guidelines or high initial content of H), Hydrogen Induced Cracks (HIC) may result from diffusion-desorption of internal hydrogen during cooling down to room temperature. Since neither hydrogen redistribution nor its internal pressure within cavities could be measured by experimental techniques, quantitative investigation is based on the modelling of related physical phenomena. A scenario of HIC formation, based on industrial feedback and modelling, has been proposed. A correlation between these defects, segregated areas and clusters of MnS (preferred initiation sites) has been revealed by expertise of HIC. A model of diffusion in heterogeneous alloys has then been proposed to assess the maximal pressure of H2 in such HIC. Simulation has shown that internal pressures above 860MPa are reached by considering an optimized Abel-Noble real gas behavior. The previous model has then been coupled to a failure mechanics procedure to characterize and quantify the crack growth parameters. Based on a parametric study, a scenario of HIC formation during the cooling has been proposed regarding process. Although results from preliminary simulations matched with feedback, the refined model based on the pressure induced elastic deformation of HIC has been developed but provided an underestimated kinetic of crack growth. Consequently, the multi-cracked nature of MnS clusters (homogenization of mechanical properties) and the updated local failure criterion appear to be a viable path to adjust predictions
Yessaad, Mouloud. "Développement d’outils prédictifs de la teneur en composés sensibles à l’oxydation au cours de la conservation dans les matrices nutritionnelles." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC080.
When stored, the active ingredients (drugs, nutrients) may be subject to degradation that may change their original properties and make them unavailable. In addition, manufacturers and hospital pharmacists carrying out pharmaceutical preparations and / or dietary supplements have the need to carry out stability studies. These studies are long and costly because they must consider all the environmental parameters likely to influence the stability of the active principle, the matrix and the packaging. The aim of this thesis is to develop a tool that allows to estimate the degradation rates of vitamins and to project on the life span of nutritional active principles based on the use of computational models integrating at the same time product characteristics, matrix and storage conditions. The project took place in several phases targeting the water-soluble vitamins. First, a development and validation of a chromatographic assay method that quantifies all vitamins in a single analysis without interference with any degradation products. A study of the influence of the most important parameters was carried out with a design of experiments. The kinetics of degradation have been studied and modeled in several approaches. From the most appropriate model, a first simulation level was designed to determine the relevant influencing factors in the degradation of vitamins in terms of exploitable data. The deliverable, the calculator, should thus help guide industrial and hospital users in the choice of accelerated aging study conditions
Dupin, Lucie. "Validation et criblage de nouvelles molécules anti-infectieuses sur microarray : applications à Pseudomonas aeruginosa." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC018/document.
Summary: Pseudomonas aeruginosa (PA) is the third pathogen involved in nosocomial diseases and the major cause of mortality of cystic fibrosis patients. PA develops resistance to antibiotics treatments. And so, developing new therapeutic strategies is a public health issue. One of the promising strategies is to inhibit virulence factors involved in the adhesion and the biofilm formation of PA. Some of these virulence factors are lectins which interact with sugars (PA-IL, PA-IIL, FliC, FliD, PilA, PilY1 and CupB6).The goal of this work is to find molecular decoys which have a strong affinity for these lectins. These are saccharidic units with a multivalent display: glycoclusters. An innovative screening tool has been developed: the glycocluster-microarray, to study lectin/glycocluster interactions. It is a microstructured glass slide where glycoclusters are immobilized by DNA Directed Immobilization (DDI). Two screening methods have been developed with this microarray: 1) the screening in solution and by competition of a saccharidic units library and2) the screening of a glycoclusters library immobilized on the microarray. Protocols of IC50 and Kd measurements have also been developed with this tool to characterize the best lectins inhibitors. This tool allows to use few amount of material (few picomoles) and to do parallel analysis.To validate the microarray, a study of the impact of glycoclusters surface density has been done. The screening of more than 150 saccharidic units allowed the selection of the ones that display the best affinity forlectins. The analysis, on microarray and molecular simulations, of the glycoclusters library displaying thesesaccharidic units and several topologies, valences and properties (aromaticity, charge,…) enable to identify key parameters of structure-affinity relationships. An anti-biofilm activity has been observed for the best glycoclusters targeting PA-IL.Testing in vivo activity of these best candidates will be explored. Targeting others lectins such as the ones on the flagella and pili of PA and involved in the early adhesion needs also to be developed. To this end, preliminary tests have been showed and some are in progress
Bodard, Sébastien. "Expérimentations et approche numérique de la transition combustion-déflagration-détonation dans les milieux pulvérulents initiée par un impact à faible vitesse." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4743/document.
The first part of the present PhD focuses on the conception and the validation of an experimental set up. The aim of the experiments is to generate one-dimensional compaction waves and to observe the media at the grains scale. Two type of powder are used : polypropylene powder and an explosive powder (RDX).The experimental apparatus uses ultra-fast cameras (50 000 images/s) to record the tests. Image correlation is used to compute the displacement and velocity fields.A multiphasic compaction model is then coded. Grain/wall friction is added as the experimental work underlined its importance. Additional work has been provided concerning the granular equation of state and its experimental determination.Numerical results are in good agreement with the experimenations, as long as the experimental set up is not deformed because of the grains' pressure.A few experiments have been done with explosive powders. The experimental set up still needs some improvement but it proved its usefullness for deflagration to detonation studies
Frank, Tobias. "Advanced visualization and modeling of tetrahedral meshes." Doctoral thesis, Vandoeuvre-les-Nancy, INPL, 2006. https://tubaf.qucosa.de/id/qucosa%3A22536.
Weiss, Elsa. "Etude cinétique de la dégradation électrochimique de composés organiques sur l'anode de diamant dope au bore : Application à la dépollution d'effluents aqueux." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00144880.
Domurath, Jan. "Stress and strain amplification in non-Newtonian fluids filled with spherical and anisometric particles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233044.
Une étude numérique sur des suspensions diluées à base d’un fluide non newtonien et de particules sphéroïdales rigides est réalisée. Le comportement de la matrice est décrit par un fluide de type Carreau. De particules sphériques et rigides est considéré en premier. Un écoulement en élongation uniaxiale autour d’une sphère est simulée. Ensuite, l’homogénéisation numérique est utilisée pour déterminer la viscosité apparente de la suspension pour différents taux de déformation et d’indices pseudoplastiques. Dans le domaine newtonien, le résultat d’Einstein donnant la viscosité d’une suspension diluée de particules sphériques et rigides est obtenu. Dans le régime en loi de puissance on constate que la viscosité intrinsèque dépend uniquement de l’indice pseudoplastique. Une autre étude numérique est effectuée pour investiguer l’influence de la forme des particules. Plusieurs écoulements autour d’une particule sphéroïdale sont simulés pour différentes orientations. Une homogénéisation numérique est ensuite utilisée pour obtenir la viscosité intrinsèque de la suspension en fonction du taux de déformation appliqué, de l’indice d’écoulement et du rapport de forme de la particule. A partir de ces résultats, il est possible d’exprimer les coefficients rhéologiques du modèle de Lipscomb. Dans le régime newtonien, les résultats coïncident avec les prédictions de Lipscomb. Dans le domaine en loi de puissance, les coefficients rhéologiques deviennent fortement dépendent de l’indice pseudoplastique. En outre, les résultats des simulations montrent que ces coefficients rhéologiques dépendent également de l’orientation des particules dans le régime non linéaire
Numerische Untersuchung zu verdünnten Suspensionen basierend auf einer nicht Newtonschen Matrixflüssigkeit und harten spheroidalen Partikeln wurde durchgeführt. Ein Carreau Fluid beschreibt die nicht Newtonsche Matrix. Zuerst wird der Spezialfall harter Kugeln betrachtet. Hierzu wird eine uniaxiale Dehnströmung um eine Kugel simuliert und numerische Homogenisierung wird verwendet um die effektive Viskosität der Suspension für verschieden aufgebrachte Deformationsgeschwindigkeiten und Verdünnungsexponenten zu bestimmen. Im Newtonschen Bereich wird die bekannte Lösung Einsteins für die Viskosität einer verdünnten Suspension harter Kugeln erhalten. Im power-law Bereich ist die intrinsische Viskosität einzig eine Funktion des Verdünnungsexponenten. Unter Nutzung der Simulationsergebnisse wird eine Modifikation des Carreau Modells vorgeschlagen. Um den Einfluss der Partikelform auf die nichtlinearen Eigenschaften zu untersuchen wird eine weitere numerische Simulationen durchgeführt. Dabei werden verschiedene Strömungen um spheroidale Partikel mit unterschiedlicher Orientierung simuliert und numerische Homogenisierung wird verwendet um die intrinsische Viskosität als Funktion der aufgebrachten Deformationsgeschwindigkeit, des Verdünnungsexponenten und des Partikelaspektverhältnisses zu bestimmen. Es ist möglich die rheologischen Parameter des Lipscomb Modells aus den Simulationsergebnissen zu bestimmen. Im Newtonschen Bereich stimmen die numerisch bestimmten Werte mit der Vorhersage Lipscomb‘s überein. Im power-law Bereich hängen die rheologischen Parameter stark vom Verdünnungsexponenten ab. Weiter kann man aus den Ergebnissen auf eine zusätzliche Abhängigkeit der rheologischen Parameter von der Partikelorientierung schließen
Hamoud, Houssam Eddine. "Linéarisation par pré-distorsion numérique d'amplificateurs de puissance pour les nouvelles générations des systèmes de télécommunications." Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0110.
Modern communications systems converge towards multi-standard operation combined with high PAPR modulation formats where the power amplifier must first be optimized in efficiency and where linearity will then be corrected by adding a predistorter. If this solution seems functional, it seems inadequate and ineffective on 5G systems where the targeted bandwidths pose both architectural problems (complexity of the observation path) and problems of accuracy of the usual behavioural models based on a simplification of the Volterra series in its discrete form (GMP, DDR) in the face of exacerbated memory effects but also of energy efficiency of the linearized system (DPD+PA). In this context, it becomes necessary to move towards a predistorter model less dependent on the characteristics of the signal to be linearized, in particular by the TPM (Two path Memory) model developed at XLIM, based on a simplification of the Volterra series in its continuous form, is independent of the characteristics of the signal to be linearized.Our work focused on evaluating the linearity performance of the classical models (GMP, DDR) and the TPM model on different power amplifiers either from simulations or from physical measurements of the PA. To do this, we have set up a simulation environmentand an evaluation bench for predistortion models with physical PA in order to quantify ACPR performance according to the variation in signal characteristics (power, frequency, statistics). All these experiments made it possible to verify, on the one hand,the poor robustness of traditional approaches (GMP/DDR) and, on the other hand, the stability of the performance of the TPM approach, whatever the scenario envisaged. This study therefore paves the way for a new generation of pre-distributor which, if extracted once and for all, would only require an update on slow dynamic phenomena (ageing) and would make it possible to consider a simplified architecture of the DPD observation path; thus improving the overall energy efficiency of the linearizedsystem
Saied, Mazen. "Etude de la stabilité et de la précision des modèles utilisés dans la correction des effets de proximité optique en photolithographie." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00682907.
Souffrin, Agathe. "Conception, synthèse et évaluation pharmacologique de maléimides, inhibiteurs potentiels de l'intégrase du VIH-1." Thesis, Tours, 2012. http://www.theses.fr/2012TOUR3801/document.
Our research team has recently developed the first inhibitors of a DDE enzyme, MOS1 transposase, an enzyme similar to the HIV-1 integrase. These molecules, having a bisfurylmaleimide structure, also showed efficacy against enzymatic activities of HIV integrase. Based on these results, we undertook the synthesis of new bisfurylmaleimides in order to identify new integrase inhibitors and propose new molecules in the fight against the virus that causes AIDS. The originality of our approach is the use of MOS1 transposase as a model for designing our molecules. Methodologies used to access these molecules are essentially involving chemistry catalyzed by transition metals but also reactions of heterocyclic chemistry such as Mitsunobu, Knoevenagel or Horner-Wadsworth-Emmons reactions. All synthesized molecules has been evaluated for their inhibitory activities on the MOS1 transposase and HIV-1 integrase. Their antiviral properties against HIV were also evaluated. Parallel to this work, we investigated the reactivity of the maleimide core in palladium-catalyzed cross-coupling reactions especially in Sonogashira couplings
Domurath, Jan. "Stress and strain amplification in non-Newtonian fluids filled with spherical and anisometric particles." Thesis, Lorient, 2017. http://www.theses.fr/2017LORIS478/document.
A numerical study of dilute suspensions based on a non-Newtonian matrix fluid and rigid spheroidal particles is performed. A Carreau fluid describes the non-Newtonian matrix. The special case of rigid spherical particles is considered. Here, a uniaxial elongational flow around a sphere is simulated and numerical homogenization is used to obtain the bulk viscosity of the dilute suspension for different applied rates of deformation and different thinning exponents. In the Newtonian regime the well-known Einstein result for the viscosity of a dilute suspension of rigid spherical particles is obtained. In the power-law regime it is found that the intrinsic viscosity depends only on the thinning exponent. Utilizing the simulation results a modification of the Carreau model for dilute suspensions with a non-Newtonian matrix fluid is proposed. To investigate the influence of the particle shape another numerical study is performed. In particular, different flows around spheroidal particles with different orientations are simulated and numerical homogenization is used to obtain the intrinsic viscosity of the suspension as function of applied rate of deformation, thinning exponent and aspect ratio. From the results it is possible to extract the rheological coefficients of the Lipscomb model. In the Newtonian regime the simulation results coincide with Lipscomb’s predictions. In the power-law regime the rheological coefficients depend strongly on the thinning exponent. Furthermore, simulation results indicate that the rheological coefficients additionally depend on the particle orientation in the non-linear regime
Jost, François Paul. "Trees in the Andes:." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-215214.
Las zonas montañosas, incluyendo la región andina son muy sensibles al cambio climático. Los agricultores de los Andes centrales del Perú están cada vez más expuestos a los efectos de la variabilidad climática. Esta investigación transdisciplinaria utiliza laboratorios de campo (field laboratories), combinando los enfoques de sistemas agrícolas y de medios de vida sostenibles, para llevar a cabo evaluaciones sociales, ecológicas y financieras con el fin de identificar estrategias sostenibles y resilientes para los agricultores andinos de pequeña escala. La primera fase de la investigación caracteriza a los sistemas agrícolas familiares, influenciados por sus contextos biofísicos y socioeconómicos, para lo cual se elaboraron dos índices de vulnerabilidad centrados en la variabilidad del clima, los cinco activos de los medios de vida y los tres componentes de la vulnerabilidad del IPCC. Estos índices muestran las condiciones de alta sensibilidad de la mayoría de las comunidades, con malas condiciones de salud y poco acceso a la infraestructura y a los servicios públicos. La capacidad de respuesta de los agricultores es a menudo limitada por la baja diversidad en las actividades agrícolas y la falta de organización. Posteriormente se identificaron las estrategias de medios de vida sostenibles. Estas incluyen la intensificación en las actividades agrícolas y la intensificación del trabajo no agrícola en las comunidades de zonas bajas y con mejor acceso. En las comunidades con menor acceso y zonas altas la migración temporal es una estrategia de afrontamiento común. Los escenarios sostenibles en estas comunidades incluyen un incremento en las estrategias de diversificación p. ej. a través de un aumento de la biodiversidad agrícola y una mayor proporción de sistemas de producción asociados con árboles. Por otra parte, la segunda fase de la investigación explora las estrategias locales para hacer frente a las sequías agrícolas y evalúa, por medio de métodos de evaluación de recursos naturales, los sistemas agroforestales como alternativa para reducir sus efectos negativos. Afectados principalmente por el aumento en la variación de las precipitaciones, los pequeños agricultores identifican a la diversificación de actividades dentro y fuera de sus parcelas agrícolas como una estrategia de adaptación frente a las sequías agrícolas que reduce la dependencia climática y la covarianza entre las actividades de subsistencia. Dentro de la introducción de variedades de cultivos y pastos más resistentes, como parte de la solución, los agricultores desean la incorporación de árboles en su sistema debido a su influencia positiva en la humedad del suelo y en los rendimientos de los cultivos. La humedad del suelo en sistemas agroforestales con árboles de eucalipto es un 10-20% mayor que en los sistemas agrícolas durante el comienzo de la estación húmeda. Las diferencias en la humedad del suelo durante el final de la estación seca y en el rendimiento de los cultivos de papa no son evidentes entre estos dos sistemas. A pesar de esto, el espacio sin siembra dejado en los sistemas agroforestales redujo la producción agrícola en un 13-17%. La tercera fase de la investigación busca maximizar la eficiencia en la asignación de recursos en los sistemas agrícolas familiares mediante el desarrollo de un modelo de optimización de programación lineal. Esta evaluación financiera respalda la necesidad de actividades adicionales no-agrícolas para agricultores con recursos más escasos. Además, con tasas de interés por debajo del 15%, el modelo siempre incluye a los sistemas de producción forestales y/o agroforestales como parte de las soluciones óptimas. Sin embargo, con el aumento de las tasas de interés, una mayor proporción de tierra se utiliza para cubrir las necesidades básicas del hogar y menos recursos están disponibles para las actividades de acumulación de capital como la silvicultura. Las variaciones introducidas en el modelo muestran que los sistemas de pastoreo son más sensibles a los cambios en los condiciones de producción. Por otro lado, la variación en los salarios de los trabajadores agrícolas y en los precios de los árboles afectan en un menor grado las soluciones óptimas, proporcionando sistemas agrícolas menos sensibles a estos cambios en el mercado. Finalmente, la incorporación de árboles en los sistemas agrícolas ha demostrado ser una estrategia de vida sostenible y resiliente a la variabilidad climática disponible para determinados sistemas agrícolas familiares de la zona de estudio
Hochgebirgsregionen einschließlich der Andenregion sind gegenüber dem Klimawandel sehr empfindlich. Die in den zentralen Anden von Peru lebenden Bauern sind mehr und mehr den Auswirkungen durch Klimaschwankungen ausgesetzt. Diese transdisziplinäre Forschung nutzt Feldlabore, die das System der landwirtschaftlichen Bewirtschaftung und Ansätze zur nachhaltigen Lebensunterhaltssicherung kombinieren, um soziale, ökologische und ökonomische Erhebungen durchzuführen, so dass nachhaltige Livelihood-Strategien für die Kleinbauern in den Anden aufgezeigt werden können. Der erste Forschungsschritt untersucht und charakterisiert die bäuerlichen Haushaltssysteme, die durch ihre biophysikalischen und sozioökonomischen Kontexte beeinflusst sind. Hierfür wurden zwei Vulnerabilitätsindizes herausgearbeitet, die Klimavariabilität und die fünf Güter des Sustainable Livelihood-Konzepts im Fokus haben, sowie die drei Vulnerabilitätskomponenten des Intergovernmental Panel on Climate Change (IPCC). Diese Indizes decken die hochgradige Sensitivität für die meisten Gemeinden auf, aufgrund des schlechten Gesundheitszustandes sowie dem Mangel an Infrastruktur und öffentlichen Dienstleistungen. Die Fähigkeit der Bauern damit umzugehen, ist zumeist begrenzt durch eine geringe Diversität und fehlende Organisation auf den Farmen. Anschließend werden nachhaltige Livelihood-Strategien aufgezeigt. Diese umfassen die Intensivierung der Arbeit in der Landwirtschaft und der Arbeitskraft außerhalb der Landwirtschaft für Gemeinden im Flachland sowie besser erreichbare Gemeinden. In Hochlandgemeinden und Gemeinden die schwer zugänglich sind, ist temporäre Migration eine geläufige Bewältigungsstrategie. Nachhaltige Szenarien in diesen Gemeinden beinhalten eine höhere Anzahl an Diversifizierungsstrategien wie die Steigerung von Agro-Biodiversität und dem Anteil an baumbasierten Produktionssystemen. Forschungsschritt II untersucht lokale Strategien, um die landwirtschaftliche Dürre zu bewältigen und bewertet – mit Hilfe von Naturressourcenbewertungsverfahren – Agroforstsysteme als eine Alternative, um die negativen Auswirkungen der Trockenzeiten zu verringern. Beeinträchtigt durch zunehmende Niederschlagsschwankungen, identifizieren Bauern die Diversifizierung von landwirtschaftlichen und nicht-landwirtschaftlichen Aktivitäten als Anpassungsstrategie bei landwirtschaftliche Dürre, wodurch die Abhängigkeit vom Wetter und die Kovarianz zwischen den Aktivitäten für den Lebensunterhalt reduziert werden kann. Neben der Einführung resistenterer Kultur- und Weidepflanzen, ist die Einbeziehung von Bäumen in das System wünschenswert, aufgrund ihres positiven Einflusses auf die Bodenfeuchte und Erträge. Die Bodenfeuchte in agroforstwirtschaftlichen Systemen mit Eukalyptusbäumen ist während der beginnenden Feuchtperiode 20% höher als in landwirtschaftlichen Systemen. Die Unterschiede der Bodenfeuchte am Ende der Trockenzeit und bezüglich des Kartoffelertrags sind zwischen diesen Systemen nicht markant, obwohl eine Fläche, auf der keine Saat ausgebracht wurde, den landwirtschaftlichen Ertrag in Agroforstsystemen um 13 bis 17% mindert. Forschungsschritt III versucht die Effizienz der Ressourcenzuordnung in Farmhaushaltssystemen zu maximieren, indem ein Optimierungsmodell mit Hilfe der linearen Programmierung entwickelt wird. Diese ökonomische Erhebung unterstreicht die Notwendigkeit zusätzlicher nichtlandwirtschaftlicher Aktivitäten für ressourcenärmere Bauern. Bei Zinsraten unter 15% umfasst das Model baumbasierte Produktionssysteme als einen Teil der optimalen Lösung. Mit steigenden Zinsraten wird jedoch eine größere Bodenfläche dazu verwendet, um die Grundbedürfnisse der Haushalte zu decken und es stehen weniger Ressourcen für Aktivitäten zur Kapitalanhäufung wie Forstwirtschaft zur Verfügung. Die in das Modell involvierten Variationen zeigen, dass Weidesysteme sensibler auf Veränderungen des Produktionsausstoßes reagieren. Schwankungen bei den Löhnen der Farmer und Veränderungen der Baumpreise beeinträchtigen hingegen die optimalen Lösungen weniger. Dadurch sind die landwirtschaftlichen Systeme gegenüber Marktschwankungen weniger anfällig. Abschließend erweist sich, dass – für bestimmte Farmhaushaltssysteme im Untersuchungsgebiet – die Einbeziehung baumbasierter Systeme als nachhaltige und resiliente Livelihood-Strategie angesichts von Klimaschwankungen nützlich ist
Regiões altomontanas, incluindo os Andes são extremamente sensíveis aos impactos das mudanças climáticas. Pequenos agricultores da região central dos Andes Peruanos estão progressivamente sendo expostos aos impactos das variações climáticas. A presente investigação transdisciplinar utiliza “field laboratories”, combinando os enfoques de sistemas rurais e dos meios de subsistência sustentáveis, visando uma avaliação social, ecológica e financeira, com intuito de se identificar estratégias resilientes e sustentáveis para os pequenos agricultores Andinos. A primeira etapa do presente estudo investiga e caracteriza os sistemas rurais, influenciados por seus contextos biofísicos e socioeconômicos, para os quais foram elaborados dois índices de vulnerabilidade focados na variabilidade climática, nos recursos dos meios de vida (cinco capitais) e nos três componentes da vulnerabilidade do IPCC. Esses índices mostram as condições altamente sensíveis da maioria das comunidades, com más condições de saúde, acesso à infra-estrutura e serviços públicos. A capacidade de resposta dos pequenos agricultores é frequentemente limitada pela baixa diversificação de actividades na exploração agricola e falta de organização. Posteriormente, foram identificadas estratégias de subsitência sustentáveis. Estas incluem a intensificação tanto do trabalho rural, quanto do não-agrícola para as comunidades de terras baixas e mais acessíveis. Para as comunidades altomontanas e com menor acesso, a migração temporária é uma estratégia de enfrentamento comum. Cenários sustentáveis para essas comunidades incluem um incremento nas estratégias de diversificação p. ex. aumentando a agrobiodiversidade e a parcela dos sistemas de produção florestais. A segunda etapa da pesquisa explora estratégias locais para lidar com as secas agrícolas e investiga, por meio de métodos de avaliação de recursos naturais, sistemas agroflorestais como alternativa para reduzir os seus efeitos negativos. Afetado principalmente pelo aumento da variação da precipitação, os agricultores identificam a diversificação tanto no trabalho rural, quanto no não-agrícola, como estratégias adaptativas contra secas agrícolas que reduzam a dependência do clima e covariância entre atividades de subsitência. Entre a introdução de culturas e de pastagens de variedades mais resistentes, a incorporação de árvores em seu sistema é desejada por conta da sua influência positiva na umidade do solo e no rendimento das culturas. A umidade do solo em sistemas agroflorestais com árvores de eucalipto é de 10-20% maior do que em sistemas agrícolas durante o início da estação chuvosa. As diferenças na umidade do solo durante o final da estação seca e na produtividade da batata não são evidentes entre estes dois sistemas. Apesar disso, o espaço sem semeadura deixado em sistemas agroflorestais reduziu a produção agrícola em 13-17%. A terceira etapa da presente investigação visa maximizar a eficiência da alocação de recursos em sistemas agrícolas familiares por meio do desenvolvimento de um modelo de otimização de programação linear. Esta avaliação financeira sustenta a necessidade de atividades não-agrícolas adicionais para agricultores com recursos escassos. Ademais, sob taxas de juros abaixo de 15%, o modelo inclui sistemas de produção florestais como parte da solução ideal. Contudo, com o aumento das taxas de juros, uma parcela maior da propriedade é usada para garantir as necessidades básicas, e portanto, menos recursos do agregado familiar estão disponíveis para atividades de acumulação de capital, tais como a silvicultura. Variações introduzidas no modelo mostram que sistemas de pastagem são mais sensíveis a mudanças nas condições de produção. Ademais, variaçãoes nos salários dos trabalhadores agrícolas e nos preços de árvores afetam menos as soluções ótimas, tornando os sistemas agrícolas menos sensíveis a estas mudanças do mercado. Por fim, a incorporação de sistemas florestais provaram ser uma estratégia de subsistência sustentável e resiliente contra a variação climática para determinados sistemas de agricultura familiar da área de estudo
Plouffe, Laurence. "Évaluation de l’association entre l’exposition postnatale aux p,p’-DDT et p,p’-DDE et l’indice de masse corporelle chez les enfants japonais." Thesis, 2018. http://hdl.handle.net/1866/23975.
Children are exposed to p,p’-dichlorodiphenyltrichloroethane (p,p’-DDT) and p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE) through placental and lactational transfer. Studies have revealed that these exposures could lead to increased body mass index (BMI) during childhood. Our aim was to assess whether exposure through breast milk is associated with BMI in Japanese children at 42 months of age. We used data from a pilot study (n=290) of the Japanese Environment and Children Study (JECS). p,p’-DDT and p,p’-DDE levels were measured in breast milk, and levels in children were estimated using a toxicokinetic model for three exposure periods (0-6 months, 6-12 months, 12-24 months). Associations with BMI at 42 months of age were assessed using multivariate linear regression models. Our study revealed no significant association with levels of p,p’-DDT measured in breast milk or estimated in children. Positive associations with p,p’-DDE were found in girls during all exposure periods. For each log increase in the estimated p,p’-DDE levels, BMI z-score increased by 0.23 (C.I. 95%: 0.01, 0.45) for the 0-6 months exposure period, 0.26 (C.I. 95%: 0.06, 0.47) for the 6-12 months exposure period and 0.24 (C.I. 95%: 0.05, 0.43) for the 12-24 months exposure period. Our results in girls were similar to those found in a previous meta-analysis that included boys and girls (BMI z-score increase of 0.13 by log increase in prenatal p,p’-DDE levels), supporting that early-life exposure to p,p’-DDE may be associated with increased BMI during childhood.
Jost, François Paul. "Trees in the Andes:: Sustainable livelihood strategies for risk reduction." Doctoral thesis, 2016. https://tud.qucosa.de/id/qucosa%3A30036.
Las zonas montañosas, incluyendo la región andina son muy sensibles al cambio climático. Los agricultores de los Andes centrales del Perú están cada vez más expuestos a los efectos de la variabilidad climática. Esta investigación transdisciplinaria utiliza laboratorios de campo (field laboratories), combinando los enfoques de sistemas agrícolas y de medios de vida sostenibles, para llevar a cabo evaluaciones sociales, ecológicas y financieras con el fin de identificar estrategias sostenibles y resilientes para los agricultores andinos de pequeña escala. La primera fase de la investigación caracteriza a los sistemas agrícolas familiares, influenciados por sus contextos biofísicos y socioeconómicos, para lo cual se elaboraron dos índices de vulnerabilidad centrados en la variabilidad del clima, los cinco activos de los medios de vida y los tres componentes de la vulnerabilidad del IPCC. Estos índices muestran las condiciones de alta sensibilidad de la mayoría de las comunidades, con malas condiciones de salud y poco acceso a la infraestructura y a los servicios públicos. La capacidad de respuesta de los agricultores es a menudo limitada por la baja diversidad en las actividades agrícolas y la falta de organización. Posteriormente se identificaron las estrategias de medios de vida sostenibles. Estas incluyen la intensificación en las actividades agrícolas y la intensificación del trabajo no agrícola en las comunidades de zonas bajas y con mejor acceso. En las comunidades con menor acceso y zonas altas la migración temporal es una estrategia de afrontamiento común. Los escenarios sostenibles en estas comunidades incluyen un incremento en las estrategias de diversificación p. ej. a través de un aumento de la biodiversidad agrícola y una mayor proporción de sistemas de producción asociados con árboles. Por otra parte, la segunda fase de la investigación explora las estrategias locales para hacer frente a las sequías agrícolas y evalúa, por medio de métodos de evaluación de recursos naturales, los sistemas agroforestales como alternativa para reducir sus efectos negativos. Afectados principalmente por el aumento en la variación de las precipitaciones, los pequeños agricultores identifican a la diversificación de actividades dentro y fuera de sus parcelas agrícolas como una estrategia de adaptación frente a las sequías agrícolas que reduce la dependencia climática y la covarianza entre las actividades de subsistencia. Dentro de la introducción de variedades de cultivos y pastos más resistentes, como parte de la solución, los agricultores desean la incorporación de árboles en su sistema debido a su influencia positiva en la humedad del suelo y en los rendimientos de los cultivos. La humedad del suelo en sistemas agroforestales con árboles de eucalipto es un 10-20% mayor que en los sistemas agrícolas durante el comienzo de la estación húmeda. Las diferencias en la humedad del suelo durante el final de la estación seca y en el rendimiento de los cultivos de papa no son evidentes entre estos dos sistemas. A pesar de esto, el espacio sin siembra dejado en los sistemas agroforestales redujo la producción agrícola en un 13-17%. La tercera fase de la investigación busca maximizar la eficiencia en la asignación de recursos en los sistemas agrícolas familiares mediante el desarrollo de un modelo de optimización de programación lineal. Esta evaluación financiera respalda la necesidad de actividades adicionales no-agrícolas para agricultores con recursos más escasos. Además, con tasas de interés por debajo del 15%, el modelo siempre incluye a los sistemas de producción forestales y/o agroforestales como parte de las soluciones óptimas. Sin embargo, con el aumento de las tasas de interés, una mayor proporción de tierra se utiliza para cubrir las necesidades básicas del hogar y menos recursos están disponibles para las actividades de acumulación de capital como la silvicultura. Las variaciones introducidas en el modelo muestran que los sistemas de pastoreo son más sensibles a los cambios en los condiciones de producción. Por otro lado, la variación en los salarios de los trabajadores agrícolas y en los precios de los árboles afectan en un menor grado las soluciones óptimas, proporcionando sistemas agrícolas menos sensibles a estos cambios en el mercado. Finalmente, la incorporación de árboles en los sistemas agrícolas ha demostrado ser una estrategia de vida sostenible y resiliente a la variabilidad climática disponible para determinados sistemas agrícolas familiares de la zona de estudio.:1 Introduction - 1 - 1.1 Introduction and justification - 1 - 1.2 Objectives and thesis statements - 2 - 1.3 Outline - 3 - 1.4 Definition of terms - 5 - 1.4.1 Vulnerability - 5 - 1.4.2 Resilience - 7 - 1.4.3 Agroforestry systems - 8 - 1.4.4 Farming system approach - 9 - 1.4.5 Farm household system - 10 - 1.4.6 Sustainable livelihood approach - 10 - 2 Framework and study site - 14 - 2.1 Theoretical framework - 14 - 2.2 Methodological framework - 18 - 2.2.1 Field laboratories - 18 - 2.2.2 Methods - 19 - 2.2.3 Methodology applied in research step I: Vulnerability in Achamayo - 21 - 2.2.4 Methodology applied in research step II: Agroforestry systems and agricultural droughts - 29 - 2.2.5 Methodology applied in research step III: Modeling small farm production systems - 33 - 2.2.6 Selection of case studies - 34 - 2.3 Study area - 35 - 2.3.1 Soils and topography - 35 - 2.3.2 Weather - 37 - 2.3.3 Agro-ecological zones and vegetation - 38 - 2.3.4 Climate change - 40 - 2.3.5 Socioeconomic characteristics - 42 - 2.3.6 Population - 43 - 2.3.7 External determinants - 71 - 2.4 Case studies - 47 - 2.4.1 Lowland communities (L) - 49 - 2.4.2 Middle access communities (M) - 50 - 2.4.3 Highland communities (H) - 51 - 3 Vulnerability in Achamayo - 53 - 3.1 Results - 53 - 3.1.1 Sustainable Livelihood Vulnerability Index (S-LVI) - 53 - 3.1.2 IPCC Livelihood Vulnerability Index (LVI-IPCC) - 68 - 3.2 Discussion - 71 - 3.2.1 Climate variability and extreme events - 71 - 3.2.2 Human capital - 71 - 3.2.3 Social capital - 71 - 3.2.4 Natural capital - 71 - 3.2.5 Physical capital - 71 - 3.2.6 Financial capital - 71 - 3.2.7 Livelihood strategies following the S-LVI and LVI-IPCC indices - 86 - 3.3 Conclusion - 92 - 4 Agroforestry systems and agricultural droughts - 95 - 4.1 Results - 96 - 4.1.1 Farmers’ experience and perception on climate variability and agricultural droughts - 96 - 4.1.2 Agricultural droughts in the farm household systems - 97 - 4.1.3 Farming forestry systems and land-use decision-making - 102 - 4.1.4 Influence of trees in the soil moisture and yield - 104 - 4.2 Discussion - 110 - 4.2.1 Climate change and agricultural droughts - 110 - 4.2.2 Farm forestry systems and land-use decision-making - 115 - 4.2.3 Influence of trees in the soil moisture and yield - 117 - 4.3 Conclusion - 121 - 5 Modeling small farm production systems: optimization of resource allocation - 123 - 5.1 Methodology - 124 - 5.1.1 Optimization Model - 126 - 5.1.2 Plan of optimization - 128 - 5.1.3 Production systems - 131 - 5.1.4 Constraints - 134 - 5.2 Results - 138 - 5.2.1 Model - 138 - 5.2.2 Interest rates - 142 - 5.2.3 Sensitivity analyses - 146 - 5.3 Discussion - 151 - 5.3.1 Cash flows - 151 - 5.3.2 Model outcomes - 152 - 5.3.3 Interest rates - 155 - 5.3.4 Sensitivity analyses - 159 - 5.4 Conclusion - 169 - 6 Synthesis - 171 - 6.1 Lessons learned - 171 - 6.1.1 Research step I - 172 - 6.1.2 Research step II - 175 - 6.1.3 Research step III - 176 - 6.2 Conclusions & outlook - 179 - 6.2.1 General conclusions - 179 - 6.2.2 Outlook - 181 - References - 185 - Appendix - 199 -
Hochgebirgsregionen einschließlich der Andenregion sind gegenüber dem Klimawandel sehr empfindlich. Die in den zentralen Anden von Peru lebenden Bauern sind mehr und mehr den Auswirkungen durch Klimaschwankungen ausgesetzt. Diese transdisziplinäre Forschung nutzt Feldlabore, die das System der landwirtschaftlichen Bewirtschaftung und Ansätze zur nachhaltigen Lebensunterhaltssicherung kombinieren, um soziale, ökologische und ökonomische Erhebungen durchzuführen, so dass nachhaltige Livelihood-Strategien für die Kleinbauern in den Anden aufgezeigt werden können. Der erste Forschungsschritt untersucht und charakterisiert die bäuerlichen Haushaltssysteme, die durch ihre biophysikalischen und sozioökonomischen Kontexte beeinflusst sind. Hierfür wurden zwei Vulnerabilitätsindizes herausgearbeitet, die Klimavariabilität und die fünf Güter des Sustainable Livelihood-Konzepts im Fokus haben, sowie die drei Vulnerabilitätskomponenten des Intergovernmental Panel on Climate Change (IPCC). Diese Indizes decken die hochgradige Sensitivität für die meisten Gemeinden auf, aufgrund des schlechten Gesundheitszustandes sowie dem Mangel an Infrastruktur und öffentlichen Dienstleistungen. Die Fähigkeit der Bauern damit umzugehen, ist zumeist begrenzt durch eine geringe Diversität und fehlende Organisation auf den Farmen. Anschließend werden nachhaltige Livelihood-Strategien aufgezeigt. Diese umfassen die Intensivierung der Arbeit in der Landwirtschaft und der Arbeitskraft außerhalb der Landwirtschaft für Gemeinden im Flachland sowie besser erreichbare Gemeinden. In Hochlandgemeinden und Gemeinden die schwer zugänglich sind, ist temporäre Migration eine geläufige Bewältigungsstrategie. Nachhaltige Szenarien in diesen Gemeinden beinhalten eine höhere Anzahl an Diversifizierungsstrategien wie die Steigerung von Agro-Biodiversität und dem Anteil an baumbasierten Produktionssystemen. Forschungsschritt II untersucht lokale Strategien, um die landwirtschaftliche Dürre zu bewältigen und bewertet – mit Hilfe von Naturressourcenbewertungsverfahren – Agroforstsysteme als eine Alternative, um die negativen Auswirkungen der Trockenzeiten zu verringern. Beeinträchtigt durch zunehmende Niederschlagsschwankungen, identifizieren Bauern die Diversifizierung von landwirtschaftlichen und nicht-landwirtschaftlichen Aktivitäten als Anpassungsstrategie bei landwirtschaftliche Dürre, wodurch die Abhängigkeit vom Wetter und die Kovarianz zwischen den Aktivitäten für den Lebensunterhalt reduziert werden kann. Neben der Einführung resistenterer Kultur- und Weidepflanzen, ist die Einbeziehung von Bäumen in das System wünschenswert, aufgrund ihres positiven Einflusses auf die Bodenfeuchte und Erträge. Die Bodenfeuchte in agroforstwirtschaftlichen Systemen mit Eukalyptusbäumen ist während der beginnenden Feuchtperiode 20% höher als in landwirtschaftlichen Systemen. Die Unterschiede der Bodenfeuchte am Ende der Trockenzeit und bezüglich des Kartoffelertrags sind zwischen diesen Systemen nicht markant, obwohl eine Fläche, auf der keine Saat ausgebracht wurde, den landwirtschaftlichen Ertrag in Agroforstsystemen um 13 bis 17% mindert. Forschungsschritt III versucht die Effizienz der Ressourcenzuordnung in Farmhaushaltssystemen zu maximieren, indem ein Optimierungsmodell mit Hilfe der linearen Programmierung entwickelt wird. Diese ökonomische Erhebung unterstreicht die Notwendigkeit zusätzlicher nichtlandwirtschaftlicher Aktivitäten für ressourcenärmere Bauern. Bei Zinsraten unter 15% umfasst das Model baumbasierte Produktionssysteme als einen Teil der optimalen Lösung. Mit steigenden Zinsraten wird jedoch eine größere Bodenfläche dazu verwendet, um die Grundbedürfnisse der Haushalte zu decken und es stehen weniger Ressourcen für Aktivitäten zur Kapitalanhäufung wie Forstwirtschaft zur Verfügung. Die in das Modell involvierten Variationen zeigen, dass Weidesysteme sensibler auf Veränderungen des Produktionsausstoßes reagieren. Schwankungen bei den Löhnen der Farmer und Veränderungen der Baumpreise beeinträchtigen hingegen die optimalen Lösungen weniger. Dadurch sind die landwirtschaftlichen Systeme gegenüber Marktschwankungen weniger anfällig. Abschließend erweist sich, dass – für bestimmte Farmhaushaltssysteme im Untersuchungsgebiet – die Einbeziehung baumbasierter Systeme als nachhaltige und resiliente Livelihood-Strategie angesichts von Klimaschwankungen nützlich ist.:1 Introduction - 1 - 1.1 Introduction and justification - 1 - 1.2 Objectives and thesis statements - 2 - 1.3 Outline - 3 - 1.4 Definition of terms - 5 - 1.4.1 Vulnerability - 5 - 1.4.2 Resilience - 7 - 1.4.3 Agroforestry systems - 8 - 1.4.4 Farming system approach - 9 - 1.4.5 Farm household system - 10 - 1.4.6 Sustainable livelihood approach - 10 - 2 Framework and study site - 14 - 2.1 Theoretical framework - 14 - 2.2 Methodological framework - 18 - 2.2.1 Field laboratories - 18 - 2.2.2 Methods - 19 - 2.2.3 Methodology applied in research step I: Vulnerability in Achamayo - 21 - 2.2.4 Methodology applied in research step II: Agroforestry systems and agricultural droughts - 29 - 2.2.5 Methodology applied in research step III: Modeling small farm production systems - 33 - 2.2.6 Selection of case studies - 34 - 2.3 Study area - 35 - 2.3.1 Soils and topography - 35 - 2.3.2 Weather - 37 - 2.3.3 Agro-ecological zones and vegetation - 38 - 2.3.4 Climate change - 40 - 2.3.5 Socioeconomic characteristics - 42 - 2.3.6 Population - 43 - 2.3.7 External determinants - 71 - 2.4 Case studies - 47 - 2.4.1 Lowland communities (L) - 49 - 2.4.2 Middle access communities (M) - 50 - 2.4.3 Highland communities (H) - 51 - 3 Vulnerability in Achamayo - 53 - 3.1 Results - 53 - 3.1.1 Sustainable Livelihood Vulnerability Index (S-LVI) - 53 - 3.1.2 IPCC Livelihood Vulnerability Index (LVI-IPCC) - 68 - 3.2 Discussion - 71 - 3.2.1 Climate variability and extreme events - 71 - 3.2.2 Human capital - 71 - 3.2.3 Social capital - 71 - 3.2.4 Natural capital - 71 - 3.2.5 Physical capital - 71 - 3.2.6 Financial capital - 71 - 3.2.7 Livelihood strategies following the S-LVI and LVI-IPCC indices - 86 - 3.3 Conclusion - 92 - 4 Agroforestry systems and agricultural droughts - 95 - 4.1 Results - 96 - 4.1.1 Farmers’ experience and perception on climate variability and agricultural droughts - 96 - 4.1.2 Agricultural droughts in the farm household systems - 97 - 4.1.3 Farming forestry systems and land-use decision-making - 102 - 4.1.4 Influence of trees in the soil moisture and yield - 104 - 4.2 Discussion - 110 - 4.2.1 Climate change and agricultural droughts - 110 - 4.2.2 Farm forestry systems and land-use decision-making - 115 - 4.2.3 Influence of trees in the soil moisture and yield - 117 - 4.3 Conclusion - 121 - 5 Modeling small farm production systems: optimization of resource allocation - 123 - 5.1 Methodology - 124 - 5.1.1 Optimization Model - 126 - 5.1.2 Plan of optimization - 128 - 5.1.3 Production systems - 131 - 5.1.4 Constraints - 134 - 5.2 Results - 138 - 5.2.1 Model - 138 - 5.2.2 Interest rates - 142 - 5.2.3 Sensitivity analyses - 146 - 5.3 Discussion - 151 - 5.3.1 Cash flows - 151 - 5.3.2 Model outcomes - 152 - 5.3.3 Interest rates - 155 - 5.3.4 Sensitivity analyses - 159 - 5.4 Conclusion - 169 - 6 Synthesis - 171 - 6.1 Lessons learned - 171 - 6.1.1 Research step I - 172 - 6.1.2 Research step II - 175 - 6.1.3 Research step III - 176 - 6.2 Conclusions & outlook - 179 - 6.2.1 General conclusions - 179 - 6.2.2 Outlook - 181 - References - 185 - Appendix - 199 -
Regiões altomontanas, incluindo os Andes são extremamente sensíveis aos impactos das mudanças climáticas. Pequenos agricultores da região central dos Andes Peruanos estão progressivamente sendo expostos aos impactos das variações climáticas. A presente investigação transdisciplinar utiliza “field laboratories”, combinando os enfoques de sistemas rurais e dos meios de subsistência sustentáveis, visando uma avaliação social, ecológica e financeira, com intuito de se identificar estratégias resilientes e sustentáveis para os pequenos agricultores Andinos. A primeira etapa do presente estudo investiga e caracteriza os sistemas rurais, influenciados por seus contextos biofísicos e socioeconômicos, para os quais foram elaborados dois índices de vulnerabilidade focados na variabilidade climática, nos recursos dos meios de vida (cinco capitais) e nos três componentes da vulnerabilidade do IPCC. Esses índices mostram as condições altamente sensíveis da maioria das comunidades, com más condições de saúde, acesso à infra-estrutura e serviços públicos. A capacidade de resposta dos pequenos agricultores é frequentemente limitada pela baixa diversificação de actividades na exploração agricola e falta de organização. Posteriormente, foram identificadas estratégias de subsitência sustentáveis. Estas incluem a intensificação tanto do trabalho rural, quanto do não-agrícola para as comunidades de terras baixas e mais acessíveis. Para as comunidades altomontanas e com menor acesso, a migração temporária é uma estratégia de enfrentamento comum. Cenários sustentáveis para essas comunidades incluem um incremento nas estratégias de diversificação p. ex. aumentando a agrobiodiversidade e a parcela dos sistemas de produção florestais. A segunda etapa da pesquisa explora estratégias locais para lidar com as secas agrícolas e investiga, por meio de métodos de avaliação de recursos naturais, sistemas agroflorestais como alternativa para reduzir os seus efeitos negativos. Afetado principalmente pelo aumento da variação da precipitação, os agricultores identificam a diversificação tanto no trabalho rural, quanto no não-agrícola, como estratégias adaptativas contra secas agrícolas que reduzam a dependência do clima e covariância entre atividades de subsitência. Entre a introdução de culturas e de pastagens de variedades mais resistentes, a incorporação de árvores em seu sistema é desejada por conta da sua influência positiva na umidade do solo e no rendimento das culturas. A umidade do solo em sistemas agroflorestais com árvores de eucalipto é de 10-20% maior do que em sistemas agrícolas durante o início da estação chuvosa. As diferenças na umidade do solo durante o final da estação seca e na produtividade da batata não são evidentes entre estes dois sistemas. Apesar disso, o espaço sem semeadura deixado em sistemas agroflorestais reduziu a produção agrícola em 13-17%. A terceira etapa da presente investigação visa maximizar a eficiência da alocação de recursos em sistemas agrícolas familiares por meio do desenvolvimento de um modelo de otimização de programação linear. Esta avaliação financeira sustenta a necessidade de atividades não-agrícolas adicionais para agricultores com recursos escassos. Ademais, sob taxas de juros abaixo de 15%, o modelo inclui sistemas de produção florestais como parte da solução ideal. Contudo, com o aumento das taxas de juros, uma parcela maior da propriedade é usada para garantir as necessidades básicas, e portanto, menos recursos do agregado familiar estão disponíveis para atividades de acumulação de capital, tais como a silvicultura. Variações introduzidas no modelo mostram que sistemas de pastagem são mais sensíveis a mudanças nas condições de produção. Ademais, variaçãoes nos salários dos trabalhadores agrícolas e nos preços de árvores afetam menos as soluções ótimas, tornando os sistemas agrícolas menos sensíveis a estas mudanças do mercado. Por fim, a incorporação de sistemas florestais provaram ser uma estratégia de subsistência sustentável e resiliente contra a variação climática para determinados sistemas de agricultura familiar da área de estudo.:1 Introduction - 1 - 1.1 Introduction and justification - 1 - 1.2 Objectives and thesis statements - 2 - 1.3 Outline - 3 - 1.4 Definition of terms - 5 - 1.4.1 Vulnerability - 5 - 1.4.2 Resilience - 7 - 1.4.3 Agroforestry systems - 8 - 1.4.4 Farming system approach - 9 - 1.4.5 Farm household system - 10 - 1.4.6 Sustainable livelihood approach - 10 - 2 Framework and study site - 14 - 2.1 Theoretical framework - 14 - 2.2 Methodological framework - 18 - 2.2.1 Field laboratories - 18 - 2.2.2 Methods - 19 - 2.2.3 Methodology applied in research step I: Vulnerability in Achamayo - 21 - 2.2.4 Methodology applied in research step II: Agroforestry systems and agricultural droughts - 29 - 2.2.5 Methodology applied in research step III: Modeling small farm production systems - 33 - 2.2.6 Selection of case studies - 34 - 2.3 Study area - 35 - 2.3.1 Soils and topography - 35 - 2.3.2 Weather - 37 - 2.3.3 Agro-ecological zones and vegetation - 38 - 2.3.4 Climate change - 40 - 2.3.5 Socioeconomic characteristics - 42 - 2.3.6 Population - 43 - 2.3.7 External determinants - 71 - 2.4 Case studies - 47 - 2.4.1 Lowland communities (L) - 49 - 2.4.2 Middle access communities (M) - 50 - 2.4.3 Highland communities (H) - 51 - 3 Vulnerability in Achamayo - 53 - 3.1 Results - 53 - 3.1.1 Sustainable Livelihood Vulnerability Index (S-LVI) - 53 - 3.1.2 IPCC Livelihood Vulnerability Index (LVI-IPCC) - 68 - 3.2 Discussion - 71 - 3.2.1 Climate variability and extreme events - 71 - 3.2.2 Human capital - 71 - 3.2.3 Social capital - 71 - 3.2.4 Natural capital - 71 - 3.2.5 Physical capital - 71 - 3.2.6 Financial capital - 71 - 3.2.7 Livelihood strategies following the S-LVI and LVI-IPCC indices - 86 - 3.3 Conclusion - 92 - 4 Agroforestry systems and agricultural droughts - 95 - 4.1 Results - 96 - 4.1.1 Farmers’ experience and perception on climate variability and agricultural droughts - 96 - 4.1.2 Agricultural droughts in the farm household systems - 97 - 4.1.3 Farming forestry systems and land-use decision-making - 102 - 4.1.4 Influence of trees in the soil moisture and yield - 104 - 4.2 Discussion - 110 - 4.2.1 Climate change and agricultural droughts - 110 - 4.2.2 Farm forestry systems and land-use decision-making - 115 - 4.2.3 Influence of trees in the soil moisture and yield - 117 - 4.3 Conclusion - 121 - 5 Modeling small farm production systems: optimization of resource allocation - 123 - 5.1 Methodology - 124 - 5.1.1 Optimization Model - 126 - 5.1.2 Plan of optimization - 128 - 5.1.3 Production systems - 131 - 5.1.4 Constraints - 134 - 5.2 Results - 138 - 5.2.1 Model - 138 - 5.2.2 Interest rates - 142 - 5.2.3 Sensitivity analyses - 146 - 5.3 Discussion - 151 - 5.3.1 Cash flows - 151 - 5.3.2 Model outcomes - 152 - 5.3.3 Interest rates - 155 - 5.3.4 Sensitivity analyses - 159 - 5.4 Conclusion - 169 - 6 Synthesis - 171 - 6.1 Lessons learned - 171 - 6.1.1 Research step I - 172 - 6.1.2 Research step II - 175 - 6.1.3 Research step III - 176 - 6.2 Conclusions & outlook - 179 - 6.2.1 General conclusions - 179 - 6.2.2 Outlook - 181 - References - 185 - Appendix - 199 -