• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 316
  • 157
  • 140
  • 68
  • 54
  • 29
  • 19
  • 10
  • 9
  • 8
  • 8
  • 6
  • 6
  • 6
  • 5
  • Tagged with
  • 927
  • 121
  • 75
  • 65
  • 64
  • 59
  • 55
  • 51
  • 50
  • 49
  • 48
  • 47
  • 45
  • 42
  • 42
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
571

Contabilidade tributária: análise dos reflexos decisórios da escolha da empresa de pequeno e médio porte pelo regime de tributação: lucro real, lucro presumido e simples nacional

Gazola, Miguel 30 January 2013 (has links)
Made available in DSpace on 2016-04-25T18:39:53Z (GMT). No. of bitstreams: 1 Miguel Gazola.pdf: 612555 bytes, checksum: 8dc57c5abfe0ff1f0badcd9f76fe2579 (MD5) Previous issue date: 2013-01-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research aims to produce a tax planning that can assist in finding an alternative, within legal aspects, to the best or lowest tax burden. Based on this concept, it is necessary to analyze all existing taxation regimes in Brazil and for a better research conclusion, it will be analyzed three companies with distinct branches and areas. Legal entities, within certain rules, will be able to choose from available taxation forms, ie, Taxable Income, National Income Deemed and Simple. Currently taxes in Brazil are very relevant to legal entities cost and expenses composition, regardless the size the company presents itself. Therefore it is necessary to analyze alternatives that would fit better for a given entity, since each tax regime has particular characteristics, are quite different, and will provide advantages or disadvantages for each company given the system chosen. Thus, by the survey raised in the case study, it will be assessed the best taxation way for each type of activity the company plays, being a selling clothes business, an industrial company that manufactures textile products or a services provider in construction / O objetivo desta pesquisa é fazer um Planejamento Tributário que poderá auxiliar na busca de uma alternativa dentro dos aspectos legais à melhor ou à menor carga tributária. A partir desse conceito, é preciso analisar todos os regimes de tributação existentes no Brasil e, para melhor conclusão da pesquisa, serão analisadas três empresas com ramos e áreas distintas. As pessoas jurídicas, dentro de certas regras, poderão optar pelas formas de tributação existentes, ou seja, Lucro Real, Lucro Presumido e Simples Nacional. Atualmente, no Brasil, os tributos são bastante relevantes na composição dos custos e despesas das pessoas jurídicas, independente da empresa ser de pequeno ou médio porte, devendo-se, desse modo, analisar as alternativas, pois cada regime de tributação possui características próprias e bastante diferenciadas, e para determinadas empresas, a escolha do regime de tributação poderá ter vantagens ou desvantagens. Dessa forma, pela pesquisa levantada no estudo comparativo, será avaliada a melhor maneira de tributação para cada tipo de atividade que a empresa desempenha, sendo uma empresa comercial que revende roupas, uma empresa industrial que fabrica papéis e uma empresa de prestação de serviços na área da construção civil
572

Detecting Cycles in GraphQL Schemas

Soames, Kieron, Lind, Jonas January 2019 (has links)
GraphQL is a database handling API created by Facebook, that provides an effective al-ternative to REST-style architectures. GraphQL provides the ability for a client to spec-ify exactly what data it wishes to receive. A problem with GraphQL is that the freedomof creating customized requests allows data to be included several times in the response,growing the response’s size exponentially. The thesis contributes to the field of GraphQLanalysis by studying the prevalence of simple cycles in GraphQL schemas. We have im-plemented a locally-run tool and webtool using Tarjan’s and Johnson’s algorithms, thatparses the schemas, creates a directed graph and enumerates all simple cycles in the graph.A collection of schemas was analysed with the tool to collect empirical data. It was foundthat 39.73 % of the total 2094 schemas contained at least one simple cycle, with the averagenumber of cycles per schema being 4. The runtime was found to be on average 11 mil-liseconds, most of which consisted of the time for parsing the schemas. It was found that44 out of the considered schemas could not be enumerated due to containing a staggeringamount of simple cycles. It can be concluded that it is possible to test schemas for cyclicityand enumerate all simple cycles in a given schema efficiently.
573

Variabilité génétique chez la bactérie radiorésistante Deinococcus radiodurans : la recombinaison entre séquences répétées et la transformation naturelle / Genetic variability in the radioresistant Deinococcus radiodurans bacterium : recombination between direct repeats and natural transformation

Ithurbide, Solenne 23 September 2015 (has links)
La bactérie Deinococcus radiodurans est connue pour sa capacité à résister à un grand nombre de traitements génotoxiques parmi lesquels on peut citer l’exposition aux rayons ionisants, aux ultra-violets, à la mitomycine C, à la dessication et au stress oxydant. Elle est capable lors d’une exposition à des doses extrêmes de rayons γ générant des centaines de cassures de l’ADN de reconstituer un génome intact en seulement 2 à 3 heures via un mécanisme original, l’ESDSA, impliquant une synthèse massive d’ADN pendant la phase de réparation des cassures de l’ADN. En plus de mécanismes efficaces de réparation de l’ADN, elle possède un kit de survie comprenant une compaction importante du nucléoïde, des mécanismes de protection des protéines contre l’oxydation, une réponse originale aux lésions de l’ADN et des protéines spécifiques induites après irradiation. Tous ces facteurs contribuent au maintien de l’intégrité du génome et à la survie de la cellule lors de l’exposition à différents agents génotoxiques. Souvent considéré comme un organisme ayant une stabilité génomique exceptionnelle, cette bactérie possède dans son génome un grand nombre de séquences répétées et des éléments mobiles et est par ailleurs naturellement compétente. Ce sont autant de facteurs pouvant participer à la variabilité génétique de cette espèce. Je me suis donc intéressée lors de ma thèse à deux processus pouvant participer à l’instabilité génétique chez D. radiodurans : la recombinaison entre séquences répétées et la transformation naturelle.L’introduction dans le génome de D. radiodurans de séquences répétées directes de 438 pb séparées par des régions d’ADN d’une longueur allant de 1479 pb à 10 500 pb m’a permis de mettre en évidence le rôle majeur joué par l’appariement simple brin (Single Strand Annealing ou SSA) impliquant la protéine DdrB, spécifique des Deinococcaceae, joue un rôle majeur dans la recombinaison « spontanée » entre les séquences répétées en absence de la recombinase RecA. L’absence de DdrB dans des souches déficientes pour la recombinaison augmente davantage la perte de viabilité observée dans ces souches ce qui suggère que le SSA participe à la prise en charge de fourches de réplication bloquées, source majeure d’instabilité génétique en absence de stress extérieur, si ces fourches ne peuvent être prise en charge par des voies impliquant des protéines de recombinaison. Je me suis également intéressée à la transformation naturelle et aux protéines impliquées dans ce processus chez D. radiodurans. J’ai pu démontrer que la protéine DprA impliquée dans la protection de l’ADN simple brin et le chargement de RecA sur l’ADN simple brin internalisé lors de la transformation de nombreuses espèces comme Streptococcus pneumoniae, Bacillus subtilis ou Helicobacter pylori, est également impliquée dans la transformation chez D. radiodurans. J’ai pu montrer également qu’en plus de jouer un rôle majeur dans la transformation par de l’ADN plasmidique, DdrB est impliquée dans la transformation par de l’ADN génomique si la protéine DprA est absente. / The bacterium Deinococcus radiodurans is known for its ability to withstand a large number of genotoxic treatments, including exposure to ionizing or ultraviolet radiation, mitomycin C, desiccation, and oxidative stress. It is able, upon exposure to extreme doses of γ-radiation generating hundreds of DNA breaks, to reconstitute an intact genome in only 2 to 3 hours via an ESDSA mechanism, involving massive DNA synthesis during DNA double strand break repair. Together with efficient DNA repair mechanisms, D. radiodurans possesses a survival kit comprising significant compaction of its nucleoid, protection mechanisms against protein oxidation, an original response to DNA damage and specific proteins induced after irradiation. All of these contribute to the maintenance of genomic integrity and cell survival upon exposure to various genotoxic agents. In spite of the idea that D. radiodurans is an organism with outstanding genomic stability, this bacterium has in its genome a large number of repeat sequences and mobile elements and is also naturally competent. All these factors contribute to the genetic variability of species. I was interested in two processes that can play a role in genetic variability in D. radiodurans: recombination between repeated sequences and natural transformation.The introduction, into the genome of D. radiodurans, of 438 bp direct repeated sequences separated by DNA regions ranging from 1,479 bp to 10,500 bp in length allowed me to demonstrate the major role of Single Strand Annealing (SSA) involving the DdrB protein specific for Deinococcaceae, in the "spontaneous" recombination between the repeated sequences in the absence of the RecA recombinase. The absence of DdrB in strains deficient for recombination further increased the loss of viability observed in these strains, suggesting that SSA is required for the management of blocked replication forks, a major source of genetic instability in the absence of external stress when these forks cannot be rescued by pathways involving recombination proteins.I was also interested in the natural transformation and proteins involved in this process in D. radiodurans. I demonstrated that DprA protein involved in DNA single strand protection and loading of RecA on single-stranded DNA internalized during transformation of many species such as Streptococcus pneumoniae, Helicobacter pylori, or Bacillus subtilis, is also involved in this process in D. radiodurans. I also showed that, in addition to playing a major role in transformation by plasmid DNA, DdrB is also involved in transformation by genomic DNA of cells devoid of the DprA protein.
574

The Discontinuous Galerkin Material Point Method : Application to hyperbolic problems in solid mechanics / Extension de la Méthode des Points Matériels à l'approximation de Galerkin Discontinue : Application aux problèmes hyperboliques en mécanique des solides

Renaud, Adrien 14 December 2018 (has links)
Dans cette thèse, la Méthode des Points Matériels (MPM) est étendue à l’approximation de Galerkin Discontinue (DG) et appliquée aux problèmes hyperboliques en mécanique des solides. La méthode résultante (DGMPM) a pour objectif de suivre précisément les ondes dans des solides subissant de fortes déformations et dont les modèles constitutifs dépendent de l’histoire du chargement. A la croisée des méthodes de types éléments finis et volumes finis, la DGMPM s’appuie sur une grille de calcul arbitraire dans laquelle des flux sont calculés au moyen de solveurs de Riemann approximés sur les arêtes entre les éléments. L’intérêt de ce type de solveurs est qu’ils permettent l’introduction de la structure caractéristique des solutions des équations aux dérivées partielles hyperboliques directement dans le schéma numérique. Les analyses de stabilité et de convergence ainsi que l’illustration de la méthode sur des simulations de problèmes unidimensionnels et bidimensionnels montrent que le schéma numérique permet d’améliorer le suivi des ondes par rapport à la MPM. Par ailleurs, un deuxième objectif poursuivi dans cette thèse consiste à caractériser la réponse des solides élastoplastiques à des sollicitations dynamiques en deux dimensions en vue d’améliorer la résolution numérique de ces problèmes. Bien qu’un certain nombre de travaux aient déjà été menés dans cette direction, les problèmes étudiés se limitent à des cas particuliers. Un cadre unifié pour l’étude de la propagation d’ondes simples dans les solides élastoplastiques en déformations et contraintes plane est proposé dans cette thèse. Les trajets de chargement suivis à l’intérieur de ces ondes simples sont de plus analysés. / In this thesis, the material point method (MPM) is extended to the discontinuous Galerkin approximation (DG) and applied to hyperbolic problems in solid mechanics. The resulting method (DGMPM) aims at accurately following waves in finite-deforming solids whose constitutive models may depend on the loading history. Merging finite volumes and finite elements methods, the DGMPM takes advantage of an arbitrary computational grid in which fluxes are evaluated at element faces by means of approximate Riemann solvers. This class of solvers enables the introduction of the characteristic structure of the solutions of hyperbolic partial differential equations within the numerical scheme. Convergence and stability analyses, along with one and two-dimensional numerical simulations,demonstrate that this approach enhances the MPM ability to track waves. On the other hand, a second purpose has been followed: it consists in identifying the response of two-dimensional elastoplastic solids to dynamic step-loadings in order to improve numerical results on these problems. Although some studies investigated similar questions, only particular cases have been treated. Thus,a generic framework for the study of the propagation of simple waves in elastic-plastic solids under plane stress and plane strain problems is proposed in this thesis. The loading paths followed inside those simple waves are further analyzed.
575

Personal identity and practical reason

Hummel, Patrik Alexander January 2018 (has links)
In this thesis, I argue that the interdependence between personal identity and practical concerns is overstated. In paradigmatic places where philosophers and common sense suggest that personal identity constrains how we should reason and care, or vice versa, the two spheres are in fact neutral to each other. I defend this claim by considering four specific cases. First, a rough characterization of the distinction between the complex and the simple view is that the former takes personal identity to consist in other relations, whereas the latter does not. I argue that the extreme claim according to which the complex view fails to give reasons for future-directed concern can be resisted. We maintain forward-looking attitudes and projects not because someone will be us, but because we relate to future selves in other, more important ways. Second, I argue that intuitions in a range of popular imaginary cases are contaminated by practical concerns whose relevance for personal identity is far from straightforward. Third, I argue that on a closer look, the complex versus simple distinction is confused. It thus cannot be what grounds differences in judgements on what matters. Debates about personal identity should be framed in terms of better understood notions. Finally, I argue that it is not a constraint on rational transformative choice that decision-maker and transforming individual are identical. Moreover, whether we are deciding for ourselves or for others - the importance of informed consent for transformative treatments is not diminished by the decision-maker's failure to projectively imagine the outcomes.
576

Precipitação e velocidade do vento na oscilação dos níveis d’água do canal São Gonçalo-RS / Precipitation and wind velocity in oscillation of water levels of the São Gonçalo channel-RS

Karsburg, Roberta Machado, Karsburg, Roberta Machado 26 October 2016 (has links)
Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2017-08-16T14:52:32Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Roberta_Machado_Karsburg_Precipitação_e_velocidade_do_vento_na_oscilação_dos_níveis_dagua.pdf: 1951339 bytes, checksum: 21d939a36d26dac261dcd69cef73e42c (MD5) / Made available in DSpace on 2017-08-16T14:52:32Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Roberta_Machado_Karsburg_Precipitação_e_velocidade_do_vento_na_oscilação_dos_níveis_dagua.pdf: 1951339 bytes, checksum: 21d939a36d26dac261dcd69cef73e42c (MD5) Previous issue date: 2016-10-26 / Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul - FAPERGS / O canal São Gonçalo se configura como um importante curso d’água, pertencente a bacia hidrográfica Mirim-São Gonçalo, que tem área de 25.000 km² e situa-se na região costeira no estado do Rio Grande do Sul. Aliado a isso, ele une a laguna dos Patos, a qual mantém conexão direta com o oceano Atlântico, à lagoa Mirim, considerada como um grande reservatório de água doce no sul do Brasil. Está situado em uma região de planície, de baixas declividades e apresenta grande complexidade e sensibilidade às oscilações dos níveis d’água, tanto em função do regime e direção de ventos como do regime de chuvas. Com isso, este trabalho teve como objetivo avaliar a influência do vento e da precipitação na oscilação do nível d`água à jusante da barragem eclusa do canal São Gonçalo-RS. A hipótese foi que a velocidade e direção do vento, juntamente com a precipitação, influenciam à oscilação dos níveis do canal São Gonçalo. Para alcançar os objetivos, foram empregados métodos de regressão linear múltipla e simples entre o nível d’água, precipitação e velocidades do vento à 2 e 7 m de altura e velocidade máxima. Para determinar a significância dos modelos de regressões lineares, foi utilizado o teste t de Student, para a verificação quais variáveis que são influenciadoras da oscilação do nível. Por fim, para indicar o grau de precisão dos modelos de regressões lineares avaliados, aplicou-se a metodologia do erro relativo médio quadrático. As direções de ventos que mostraram-se mais influenciadoras no processo de oscilação dos níveis d’água à jusante do canal São Gonçalo, foram as de sudeste (SE), sul (S) e oeste (O). A variável com maior influência no processo de oscilação dos níveis d’água à jusante da barragem eclusa do canal São Gonçalo, foi a velocidade máxima do vento (VMáx). / São Gonçalo is an important watercourse, belonging to the Mirim-São Gonçalo hydrographic basin, which has an area of 25,000 km² and is located in the coastal region of the state of Rio Grande do Sul. The Patos lagoon, which maintains a direct connection with the Atlantic Ocean, to Mirim lagoon, considered as a large reservoir of fresh water in southern Brazil. It’s situated in a lowland lowland region and presents great complexity and sensitivity to the fluctuations of water levels, both due to the regime and direction of the winds and the rainfall regime. The objective of this work was to evaluate the influence of wind and precipitation on the oscillation of the water level downstream of the São Gonçalo channel dam. The hypothesis was that the velocity and direction of the wind, along with the precipitation, influence the oscillation of the levels of the São Gonçalo channel. To achieve the objectives, multiple linear simple regression methods were used between water level, precipitation and wind velocities at 2 and 7 m in height and at maximum velocity. To determine the significance of the linear regression models, the Student's t test was used to verify which variables are influencing the level oscillation. Finally, to indicate the degree of precision of the linear regression models evaluated, the methodology of the relative mean square error was applied. The directions of the winds that were most influential in the process of oscillation of the water levels downstream of the São Gonçalo channel were those of the southeast (SE), south (S) and west (O). The variable with the greatest influence on the oscillation process of the water levels downstream of the São Gonçalo channel dam was the maximum wind speed.
577

O método simplex e o método gráfico na resolução de problemas de otimização / The simplex method and graph method in the optimization problem solving

Silva, Adriana Batista da 29 April 2016 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-10T13:09:08Z No. of bitstreams: 2 Dissertação - Adriana Batista da Silva - 2016.pdf: 3286914 bytes, checksum: 7be43fd6757af8224a3358e36202f297 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-10T13:12:09Z (GMT) No. of bitstreams: 2 Dissertação - Adriana Batista da Silva - 2016.pdf: 3286914 bytes, checksum: 7be43fd6757af8224a3358e36202f297 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-10T13:12:09Z (GMT). No. of bitstreams: 2 Dissertação - Adriana Batista da Silva - 2016.pdf: 3286914 bytes, checksum: 7be43fd6757af8224a3358e36202f297 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-04-29 / Financiadora de Estudos e Projetos- Finep / Linear Programming is an operational search tool applied to problem solving aimed at the optimization of a study system. This study aims to show some applications of linear programming and how it can be used as a motivating teaching skills of Mathematics in High school. We will cover two methods of linear programming problems resolution, Graphics resolution method and the algebraic solution way, which is the Simple Method. We so decided to solve under the assistance of these two methods quoted, optimization problems with two or three variables, since the problems with multiple variables do not match the curriculum of mathematics for high school. We suggest the use of two free applications for mobile phones, to solve optimization problems with several variables, in order to contribute in a di erent approach, seeking to boost in students, interest in the study of mathematics. / A Programação Linear é uma ferramenta da Pesquisa Operacional aplicada à solução de problemas que objetivam a otimização de um sistema de estudo. O presente trabalho busca mostrar algumas aplicações da Programação Linear e como ela pode ser utilizada como elemento motivador no ensino da Matemática no Ensino Médio. Abordaremos dois métodos de resolução de problemas de Programação Linear, o método de Resolução Grá ca e a forma algébrica de solução que é o Método Simplex. Vamos solucionar com auxílio desses dois métodos citados, problemas de otimização com duas e três variáveis, já que problemas com várias variáveis não se adequam a matriz curricular de Matemática para o Ensino Médio. Sugerimos a utilização de dois aplicativos gratuitos para celulares, que solucionam problemas de otimização com várias variáveis como forma de contribuir com uma abordagem diferente, visando despertar no aluno, o interesse pelo estudo da Matemática.
578

Discriminações simples, classes funcionais e classes de equivalência / Simple discriminations, functional classes and equivalence classes

Daniela de Souza Canovas 12 June 2013 (has links)
O presente estudo procurou investigar se procedimentos de discriminações simples, que produzem classes funcionais, poderiam produzir também classes de equivalência. No Experimento 1 utilizou-se o procedimento de discriminações simples sucessivas e reversões. Quatro adultos foram expostos ao treino em que respostas aos estímulos S+ (A1, B1 e C1), mas não aos S- (A2, B2 e C2), eram reforçadas. A seguir, os participantes eram expostos a reversões repetidas das contingências. Testes de relações condicionais emergentes (BA, CB, AC e CA) foram conduzidos por meio do procedimento go/no-go com estímulos compostos, para evitar que os testes envolvessem sequências de respostas possivelmente reforçadas no treino anterior. Os quatro participantes apresentaram responder consistente com a formação de classes funcionais e, três deles, também apresentaram responder indicativo da formação de classes de equivalência. O Experimento 2, investigou se um procedimento de discriminações simples, estabelecidas por meio de respostas diferenciais, que evitava o estabelecimento de sequências de respostas ou discriminações condicionais inadvertidamente, produziria classes funcionais e de equivalência. Outros quatro adultos típicos foram expostos ao treino, em que a Reposta 1 (R1) era reforçada apenas quando emitida na presença de A1, B1 e C1, enquanto a Resposta 2 (R2) era reforçada apenas na presença de A2, B2 e C2. A seguir, uma nova resposta era treinada na presença de um estímulo de cada classe (A1-R3 e A2-R4). Por fim, foram conduzidos Testes de transferência de função e Testes de relações condicionais emergentes (AB, BC, BA, CB, AC e CA) por meio do procedimento go/no-go com estímulos compostos. Os quatro participantes apresentaram responder consistente com a formação de classes funcionais e classes de equivalência. O Experimento 3, teve o objetivo de replicar o procedimento do Experimento 2 com crianças pré-escolares com desenvolvimento típico. Oito das onze crianças formaram classes funcionais e duas delas apresentaram responder consistente com a formação de classes de equivalência, avaliadas por meio do procedimento go/no-go. Outras três crianças também apresentaram responder indicativo da formação de classes de equivalência, apenas posteriormente, quando expostas a testes com o procedimento MTS. O Experimento 4 teve o objetivo de investigar com outras onze crianças se o emprego de outras topografias de respostas, durante o treino de respostas diferenciais, diminuiria a variabilidade dos resultados observados no Experimento 3. Os resultados mostraram que em uma das condições experimentais empregadas, em que as respostas eram mover o mouse ou clicar, nenhuma das cinco crianças apresentou responder consistente com a formação de classes funcionais. Em outra condição experimental, em que as respostas motoras eram gestos, três das seis crianças apresentaram formação de classes funcionais e de equivalência (avaliadas por meio do procedimento go/no-go com estímulos compostos). Em conjunto, os resultados dos quatro experimentos demonstram que procedimentos de discriminações simples podem produzir classes funcionais e também classes de equivalência e apontam que a variabilidade dos desempenhos caracteristicamente encontrada nos experimentos com crianças pode sugerir o efeito de variáveis críticas na aquisição das discriminações e formação de classes funcionais com esta população / This study investigated if simple discrimination procedures, which produce functional classes, could also produce equivalence classes. In Experiment 1, a simple successive discrimination reversal training was used. Four adults were exposed to training in which responses to S+ (A1, B1 and C1), but not to S- (A2, B2 and C2), were reinforced. Next, the participants were exposed to repeated-reversal training. Finally, Emergent conditional relations Tests (BA, CB, AC and CA) were conducted using the go/no-go procedure with compound stimuli to avoid tests involving response sequences adventitiously reinforced during the previous training. The four participants responded consistently with functional class formation and three of them also showed performance indicative of equivalence class formation. Experiment 2 investigated whether a simple discrimination training via differential responses would produce functional and equivalence classes. This training procedure avoided the inadvertently establishment of conditional discriminations or response sequences. Four additional adults were exposed to training procedure in which Response 1 (R1) was reinforced only when emitted in the presence of A1, B1 or C1 and Response 2 (R2) was reinforced only in the presence of A2, B2 or C2. Next, a new response was trained in the presence of one member of each class (A1-R3, A2-R4). Finally, a Transfer of function Test and Emergent conditional relations Tests (AB, BC, BA, CB, AC e CA) were conducted. The four participants responded consistently with functional and equivalence class formation. The purpose of Experiment 3 was replicating Experiment 2 with typically developing preschool children. Eight of the eleven children showed performance indicative of functional class formation and two of them also responded consistently with equivalence class formation, evaluated with the go/no-go procedure. The performance of other three children was also indicative of equivalence class formation, evaluated in tests with the MTS procedure. Experiment 4 investigated, with eleven additional children, if simple discrimination training with different responses topographies would decrease the between subject variability observed in Experiment 3. The results indicated that none of the participants responded consistently with functional class formation in one of the experimental conditions. In the other experimental condition, in which the differential responses were gestures, three of six participants responded consistently with functional and equivalence class formation (evaluated by the go/no-go procedure with compound stimuli). All together, the results of the four experiments demonstrate that simple discrimination procedures can produce functional and also equivalence classes. The variability between subjects specifically found in Experiments 3 and 4 suggests the effects of critical variables on the acquisition of the simple discriminations and functional class formation with children
579

Simple Rules for Climate Policy and Integrated Assessment

van der Ploeg, Frederick, Rezai, Armon 01 1900 (has links) (PDF)
A simple integrated assessment framework that gives rules for the optimal carbon price, transition to the carbon-free era and stranded carbon assets is presented, which highlights the ethical, economic, geophysical and political drivers of optimal climate policy. For the ethics we discuss the role of intergenerational inequality aversion and the discount rate, where we show the importance of lower discount rates for appraisal of longer run benefit and of policy makers using lower discount rates than private agents. The economics depends on the costs and rates of technical progress in production of fossil fuel, its substitute renewable energies and sequestration. The geophysics depends on the permanent and transient components of atmospheric carbon and the relatively fast temperature response, and we allow for positive feedbacks. The politics stems from international free-rider problems in absence of a global climate deal. We show how results change if different assumptions are made about each of the drivers of climate policy. Our main objective is to offer an easy back-on-the-envelope analysis, which can be used for teaching and communication with policy makers.
580

IRRIGATION, ADAPTATION, AND WATER SCARCITY

Iman Haqiqi (7481798) 17 October 2019 (has links)
<p>Economics is about the management of scare resources. In agricultural production, water stress and excess heat are the main constraints. The three essays of this dissertation try to improve our understandings of how climate and water resources interact with agricultural markets, and how global changes in agricultural markets may affect water resources. I construct empirical and simulation models to explain the interplay between agriculture and water. These models integrate economic theories with environmental sciences to analyze the hydroclimatic and economic information at different geospatial scales in a changing climate. </p> <p>In the first essay, I illustrate how irrigation, as a potential adaptation channel, can reduce the volatility of crop yields and year-on-year variations caused by the projected heat stress. This work includes estimation of yield response to climate variation for irrigated and rainfed crops; and global projections of change in the mean and the variation of crop yields. I use my estimated response function to project future yield variations using NASA NEX-GDDP climate data. I show that the impact of heat stress on rainfed corn is around twice as big as irrigated practices. </p> <p>In the second essay, I establish a framework for estimating the value of soil moisture for rainfed production. This framework is an extension of Schlenker and Roberts (2009) model enabled by the detailed soil moisture information available from the Water Balance Model (WBM). An important contribution is the introduction of a cumulative yield production function considering the daily interaction of heat and soil moisture. I use this framework to investigate the impacts of soil moisture on corn yields in the United States. However, this framework can be used for the valuation of other ecosystem services at daily basis.</p> <p>In the third essay, I have constructed a model that explains how the global market economy interacts with local land and water resources. This helps us to broaden the scope of global to local analysis of systems sustainability. I have employed SIMPLE-G-W (a Simplified International Model of agricultural Prices, Land use, and the Environment- Gridded Water version) to explain the reallocation across regions. The model is based on a cost minimization behavior for irrigation technology choice for around 75,000 grid cells in the United States constrained by water rights, water availability, and quasi-irreversibility of groundwater supply. This model is used to examine the vulnerability of US land and water resources from global changes.</p>

Page generated in 0.0199 seconds