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  • 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.
1

The role of Assortative Mating in the Initial Stages of Sympatric and Parapatric Speciation

Rova, Emma January 2010 (has links)
Divergence in the face of gene flow is perhaps the most wildly disputed subject among researchers through time. The debate is an old one and we find its origin as far back as the era of Darwin. The theories dealing with sympatric and parapatric speciation, its processes and ecological conditions, are numerous and the empirical data supporting the ideas is constantly growing. However, the reach of a consensus almost seem as distant as ever. Two fundamental prerequisites can be identified for the evolution of divergence with gene flow, the act of disruptive selection, and the development of assortative mating. A set of models in which speciation with gene flow seem particularly likely is when a shift occurs in host preference in phytophagous insects and mating takes place on the host. In the work behind this thesis, the role of assortative mating in the initial stages of sympatric and parapatric speciation has been studied, as has the interaction between assortative mating and inbreeding and how it effects speciation in small sympatric populations, an aspect not much attended to earlier in the literature. My results show that assortative mating based on resource preference, can evolve rapidly upon secondary contact, and even in parapatric populations with a migration rate of 8% (13-15 individuals) per generation. However for assortative mating to be maintained selection against hybrids is needed. My results also suggests that small inbred populations have a hard time coping with strong assortative mating an as a consequence tend to relax their mating preferences to avoid inbreeding depression. Based on these results, I advocate for the importance of considering not only assortative mating in itself, but also the joint effects of assortative mating and inbreeding when dealing with theories of speciation with gene flow.
2

Conversational Recasts Versus Imitation Intervention: An Examination of Experimental Evidence

Millard, M., Venkatesan, S. K., Williams, A. Lynn 01 January 2009 (has links)
No description available.
3

Temperature Increase Effects on Sagebrush Ecosystem Forbs: Exprimental Evidence and Range Manager Perspectives

Whitcomb, Hilary Louise 01 May 2011 (has links)
Sagebrush plant communities are among the most threatened in North America. This project had two goals: to test how increased temperature affects native and nonnative forb species common to the Western sagebrush region and to evaluate land manager beliefs about changes in their ecosystems, including those affecting forb species. Native forbs Sphaeralcea munroana, Crepis acuminata, Linum lewisii, Penstemon palmeri, and Oenothera pallida and non-natives Erodium cicutarium and Lactuca serriola were each subjected to two treatments: experimental warming using open-top chambers and a control. Knowing how forbs used in restoration might respond to future conditions is both practical and economical information for land managers. Responses to an open-top chamber treatment suggest that S. munroana, L. lewisii, and P. palmeri may be resilient to predicted increases in temperature, while C. acuminata and O. pallida should be used with caution. As expected, temperature did not affect E. cicutarium fitness but did lead to earlier germination. This result supports the concept that competitive interactions between non-natives and natives could be compounded by increased temperature. Transplanted L. serriola was negatively affected by warming. Semi-structured phone interviews of range managers in Utah, Idaho, Nevada, Wyoming, Oregon, and Montana addressed demographics, local climate and land changes, and forb knowledge. Additionally, local long-term climate data sets were compared to responses. Most states respondents were evenly split about beliefs of climate change in their area (half said there were no changes, and have said they thought there were some changes). Montana was the exception; Montana’s recent increases in climate-related events may explain most of the managers noting changes. Managers that had more years at their job gave more qualified, but also more accurate climate answers. Managers saying there was no change tended to base their answers on recent weather conditions, while managers that said they did notice changes tended to base their answers on long-term patterns. Forbs typically were not viewed as an important indicator of ecosystem health or resilience. This study indicates restoration organizations might benefit from more specified outreach to managers which focuses on local climate, forbs (especially those known to be used by Greater sage-grouse), and solutions.
4

Evidência não evidente: as explicações em uma disciplina de química geral / Evidence not so evident: explanations in a general chemistry course

Lemes, Anielli Fabíula Gavioli 24 August 2016 (has links)
O presente trabalho recorre à Filosofia da Química como viés para investigar o processo de ensino-aprendizagem em duas disciplinas de Química Geral em um curso para formação de químicos. A investigação se baseou em diversas fontes: respostas dos estudantes via questionários, gravações de aulas, atividade dos estudantes em aula, resposta esperada pelo professor para essa atividade e entrevistas com professores das disciplinas, a fim de possibilitar a triangulação dos resultados. Procurou-se caracterizar a preferência dos estudantes e professores acerca dos tipos de teorias e evidências utilizadas em suas explicações. As teorias hipotéticas e as evidências experimentais mediadas por instrumentos analíticos, como o espectrofotômetro, foram preferidas pelos professores, mas os estudantes mostraram dificuldades em lidar com elas neste momento inicial de sua formação superior. Foi percebida, também, uma tensão subjacente entre a química das moléculas e a química das substâncias, cuja relação está internalizada pelos professores mas não pelos alunos, e que se reflete em suas escolhas pelos tipos de explicações. Essa tensão pode ser entendida a partir da relação entre fazer química (baseado fortemente em instrumentos para separação e caracterização de compostos, e nas teorias que descrevem a química das moléculas) e ensinar química em uma disciplina introdutória (como escolher conteúdos e abordagens que permitam entender a relação entre o nível fenomenológico macroscópico e os modelos explicativos submicroscópicos). Para o químico em formação, observar uma evidência experimental e relacioná-la com uma teoria que envolve entidades submicroscópicas para formar uma explicação é um processo muito complexo. Esse processo fica ainda mais complexo quando a evidência a ser utilizada é mediada por um instrumento. Assim, os resultados obtidos e apresentados nesta tese apontam para a questão de que a diferença entre os tipos de evidências experimentais (mediadas e não mediadas) não pode ser tratada como um conhecimento tácito no ensino superior de Química Geral. / This thesis takes the philosophy of chemistry as a guide to investigate the process of teaching and learning in two general chemistry disciplines in a training course for chemists. In order to enable triangulation of results, the study relied on several sources: students\' responses to questionnaires, recording of classes, classroom students\' activities, expected responses by the lecturer for activities, and interviews with the lecturers. The investigation sought to characterize the preferences of students and lecturers about the kinds of theories and evidences used in their explanations. Lecturers preferred hypothetical theories and experimental evidences mediated by analytical instruments such as the spectrophotometer. However, students showed difficulties in dealing with such theories and mediated evidences in this initial stage of their education. A subjacent tension between the chemistry of molecules and the chemistry of substances, whose relation is internalized by the lecturers but not by the students, was also reflected in their choices for the types of explanations. Such tension can be understood considering the relationship between making chemistry (which is strongly based on instruments for separation and characterization of compounds, and on theories which describe the behavior of molecules) and teaching chemistry on an introductory course (which requires the choosing of contents and approaches to describe the relationship between the macroscopic phenomenological level and the submicroscopic explanatory models). For a chemistry undergraduate, observing an experimental evidence and relating it to a theory which involves submicroscopic entities to form an explanation is a very complex process. This process becomes even more complex when the evidence to be used is mediated by instruments. Thus, the results obtained and presented in this thesis point to the issue that the difference between the types of experimental evidences (direct or mediated) cannot be treated as a tacit knowledge in a General Chemistry university course.
5

Ensaios em economia da educação

Camargo, Juliana 22 May 2017 (has links)
Submitted by Juliana Camargo (juliana.camargo@fgv.br) on 2017-06-20T18:32:20Z No. of bitstreams: 1 Tese_JulianaCamargo_deposito.pdf: 710664 bytes, checksum: d23c73a7672666813e5e6bce333fabd8 (MD5) / Rejected by Suzinei Teles Garcia Garcia (suzinei.garcia@fgv.br), reason: Boa tarde Juliana, As primeiras páginas do trabalho em português, língua de acordo com a instituição/país somente o título do trabalho em inglês e a palavra agradecimento em caixa alta. Grata. Suzi 3799/7876 on 2017-06-21T19:18:48Z (GMT) / Submitted by Juliana Camargo (juliana.camargo@fgv.br) on 2017-06-21T20:57:09Z No. of bitstreams: 1 Tese_JulianaCamargo_deposito.pdf: 710392 bytes, checksum: 1c06b951e5ad9f2355def00ccf055931 (MD5) / Approved for entry into archive by Suzinei Teles Garcia Garcia (suzinei.garcia@fgv.br) on 2017-06-21T21:18:04Z (GMT) No. of bitstreams: 1 Tese_JulianaCamargo_deposito.pdf: 710392 bytes, checksum: 1c06b951e5ad9f2355def00ccf055931 (MD5) / Made available in DSpace on 2017-06-22T12:57:38Z (GMT). No. of bitstreams: 1 Tese_JulianaCamargo_deposito.pdf: 710392 bytes, checksum: 1c06b951e5ad9f2355def00ccf055931 (MD5) Previous issue date: 2017-05-22 / The aim of this study is to provide rigorous evidence of the impact of a brazilian vocational education and training program on its beneficiaries. For this, we took advantage of the selection criteria for the program, in which the beneficiaries were selected through a lottery . Besides, our unique dataset allow us to evaluate the effect of the intervention not only on the economic dimension, but also on human capital, socio-emotional, crime and risky behavior outcomes. This is a valuable contribution since there is a lack of evidence in the literature about the impact of VET programs on these outcomes. Our estimations were based on ITT and LATE strategies. Overall, our results indicated that, at least in the short-run, there was no effect of the program on conventional labor market outcomes, such as employment and formal work probability and wages. Also, we found no effect in socio-emotional, crime and risky behavior dimensions. However, our results pointed towards a possible heterogeneity of the program, since we found positive and significant effects of the intervention on women, specially in labor market (formal work probability and wage) and socio-emotional (extraversion) outcomes. / O objetivo deste estudo é fornecer evidências rigorosas do impacto de um programa brasileiro de educação técnica de nível médio sobre seus beneficiários. Para tanto, nós aproveitamos o critério de seleção do programa, no qual os beneficiários são selecionados através de um sorteio. Além disso, nosso banco de dados único nos permite avaliar o efeito da intervenção não apenas na dimensão econômica, mas também em dimensões como capital humano, habilidades socioemocionais e crime e comportamento de risco. Essa é uma contribuição relevante, uma vez que na literatura há uma lacuna de evidências sobre o impacto de educação técnica nesses resultados. Nossas estimações foram baseadas em estratégias de ITT e LATE. De forma geral, nossos resultados indicam que, ao menos no curto prazo, não há efeito do programa nos resultados de mercado de trabalho, tai como empregabilidade, emprego formal e salários. Ademais, nós também não encontramos efeitos do programa em outras dimensões como socio-emocionais, crime e comportamento de risco. Entretanto, nossos resultados sugerem que há uma heterogeneidade nos efeitos do programa, uma vez que encontramos efeitos positivos e significantes do programa sobre as mulheres, especialmente em resultados do mercado de trabalho (emprego formal e salário) e habilidades socioemocionais (extroversão).
6

Evidência não evidente: as explicações em uma disciplina de química geral / Evidence not so evident: explanations in a general chemistry course

Anielli Fabíula Gavioli Lemes 24 August 2016 (has links)
O presente trabalho recorre à Filosofia da Química como viés para investigar o processo de ensino-aprendizagem em duas disciplinas de Química Geral em um curso para formação de químicos. A investigação se baseou em diversas fontes: respostas dos estudantes via questionários, gravações de aulas, atividade dos estudantes em aula, resposta esperada pelo professor para essa atividade e entrevistas com professores das disciplinas, a fim de possibilitar a triangulação dos resultados. Procurou-se caracterizar a preferência dos estudantes e professores acerca dos tipos de teorias e evidências utilizadas em suas explicações. As teorias hipotéticas e as evidências experimentais mediadas por instrumentos analíticos, como o espectrofotômetro, foram preferidas pelos professores, mas os estudantes mostraram dificuldades em lidar com elas neste momento inicial de sua formação superior. Foi percebida, também, uma tensão subjacente entre a química das moléculas e a química das substâncias, cuja relação está internalizada pelos professores mas não pelos alunos, e que se reflete em suas escolhas pelos tipos de explicações. Essa tensão pode ser entendida a partir da relação entre fazer química (baseado fortemente em instrumentos para separação e caracterização de compostos, e nas teorias que descrevem a química das moléculas) e ensinar química em uma disciplina introdutória (como escolher conteúdos e abordagens que permitam entender a relação entre o nível fenomenológico macroscópico e os modelos explicativos submicroscópicos). Para o químico em formação, observar uma evidência experimental e relacioná-la com uma teoria que envolve entidades submicroscópicas para formar uma explicação é um processo muito complexo. Esse processo fica ainda mais complexo quando a evidência a ser utilizada é mediada por um instrumento. Assim, os resultados obtidos e apresentados nesta tese apontam para a questão de que a diferença entre os tipos de evidências experimentais (mediadas e não mediadas) não pode ser tratada como um conhecimento tácito no ensino superior de Química Geral. / This thesis takes the philosophy of chemistry as a guide to investigate the process of teaching and learning in two general chemistry disciplines in a training course for chemists. In order to enable triangulation of results, the study relied on several sources: students\' responses to questionnaires, recording of classes, classroom students\' activities, expected responses by the lecturer for activities, and interviews with the lecturers. The investigation sought to characterize the preferences of students and lecturers about the kinds of theories and evidences used in their explanations. Lecturers preferred hypothetical theories and experimental evidences mediated by analytical instruments such as the spectrophotometer. However, students showed difficulties in dealing with such theories and mediated evidences in this initial stage of their education. A subjacent tension between the chemistry of molecules and the chemistry of substances, whose relation is internalized by the lecturers but not by the students, was also reflected in their choices for the types of explanations. Such tension can be understood considering the relationship between making chemistry (which is strongly based on instruments for separation and characterization of compounds, and on theories which describe the behavior of molecules) and teaching chemistry on an introductory course (which requires the choosing of contents and approaches to describe the relationship between the macroscopic phenomenological level and the submicroscopic explanatory models). For a chemistry undergraduate, observing an experimental evidence and relating it to a theory which involves submicroscopic entities to form an explanation is a very complex process. This process becomes even more complex when the evidence to be used is mediated by instruments. Thus, the results obtained and presented in this thesis point to the issue that the difference between the types of experimental evidences (direct or mediated) cannot be treated as a tacit knowledge in a General Chemistry university course.

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