948 resultados para instrumental rationalism
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A preocupação primordial, que se notará no decorrer do presente trabalho, é a de desenvolver um estudo que forneça, ao investidor imobiliário, subsídios sobre o tecido urbano de São Paulo, através de uma visão global, a fim de facilitar a escolha da área onde atuar acredita-se, mais precisamente, que a grande contribuição deste estudo reside neste propósito de querer equipar o investidor imobiliário com ideias que lhe serão relevantes para atingir um desempenho mais eficiente.
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This paper considers two-sided tests for the parameter of an endogenous variable in an instrumental variable (IV) model with heteroskedastic and autocorrelated errors. We develop the nite-sample theory of weighted-average power (WAP) tests with normal errors and a known long-run variance. We introduce two weights which are invariant to orthogonal transformations of the instruments; e.g., changing the order in which the instruments appear. While tests using the MM1 weight can be severely biased, optimal tests based on the MM2 weight are naturally two-sided when errors are homoskedastic. We propose two boundary conditions that yield two-sided tests whether errors are homoskedastic or not. The locally unbiased (LU) condition is related to the power around the null hypothesis and is a weaker requirement than unbiasedness. The strongly unbiased (SU) condition is more restrictive than LU, but the associated WAP tests are easier to implement. Several tests are SU in nite samples or asymptotically, including tests robust to weak IV (such as the Anderson-Rubin, score, conditional quasi-likelihood ratio, and I. Andrews' (2015) PI-CLC tests) and two-sided tests which are optimal when the sample size is large and instruments are strong. We refer to the WAP-SU tests based on our weights as MM1-SU and MM2-SU tests. Dropping the restrictive assumptions of normality and known variance, the theory is shown to remain valid at the cost of asymptotic approximations. The MM2-SU test is optimal under the strong IV asymptotics, and outperforms other existing tests under the weak IV asymptotics.
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Esta dissertação se propõe ao estudo de inferência usando estimação por método generalizado dos momentos (GMM) baseado no uso de instrumentos. A motivação para o estudo está no fato de que sob identificação fraca dos parâmetros, a inferência tradicional pode levar a resultados enganosos. Dessa forma, é feita uma revisão dos mais usuais testes para superar tal problema e uma apresentação dos arcabouços propostos por Moreira (2002) e Moreira & Moreira (2013), e Kleibergen (2005). Com isso, o trabalho concilia as estatísticas utilizadas por eles para realizar inferência e reescreve o teste score proposto em Kleibergen (2005) utilizando as estatísticas de Moreira & Moreira (2013), e é obtido usando a teoria assintótica em Newey & McFadden (1984) a estatística do teste score ótimo. Além disso, mostra-se a equivalência entre a abordagem por GMM e a que usa sistema de equações e verossimilhança para abordar o problema de identificação fraca.
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In this work we focus on tests for the parameter of an endogenous variable in a weakly identi ed instrumental variable regressionmodel. We propose a new unbiasedness restriction for weighted average power (WAP) tests introduced by Moreira and Moreira (2013). This new boundary condition is motivated by the score e ciency under strong identi cation. It allows reducing computational costs of WAP tests by replacing the strongly unbiased condition. This latter restriction imposes, under the null hypothesis, the test to be uncorrelated to a given statistic with dimension given by the number of instruments. The new proposed boundary condition only imposes the test to be uncorrelated to a linear combination of the statistic. WAP tests under both restrictions to perform similarly numerically. We apply the di erent tests discussed to an empirical example. Using data from Yogo (2004), we assess the e ect of weak instruments on the estimation of the elasticity of inter-temporal substitution of a CCAPM model.
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The thesis presents a systematic description about the meaning, as Skemp, relational understanding and understanding instrumental, in the context of mathematics learning, being that we had as a guide his understanding of the schema. Especially, we analyze some academic productions, in the area of Mathematics Education, who used the categories of understanding relational and instrumental understanding how evaluative instrument and we see that in most cases the analysis is punctual. Being so, whereas the inherent understanding relational schema has a network of connected ideas and non-insulated, we investigated if the global analysis, where it is the understanding of the diversity of contributory concepts for formation of the concept to be learned, is more appropriate than the punctual, where does the understanding of concepts so isolated. For this, we apply a teaching module, having as main content the Quaternos Pythagoreans using History of Mathematics and the work of Bahier (1916). With the data we obtained the teaching module to use the global analysis and the punctual analysis, using research methodology the Case Study, and consequently we conduct our inferences about the levels of understanding of the subject which has made it possible for us to investigate the ownership of global analysis at the expense of punctual analysis. On the opportunity, we prove the thesis that we espouse in the course of the study and, in addition, we highlight as a contribution of our research evidence of need for a teaching of mathematics that entices the relational understanding and that evaluation should be global, being necessary to consider the notion of schema and therefore know the schematic diagram of the concept that will be evaluated
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This present work has as objective to analyze the interpretation of the syntactic and semantic meaning performed by third graders in the nominal groups (NGs) with attributive adjectives in the English language in a text of the final exam in the ESP (English for Specific Purposes) discipline. The corpus is made up of 30 exams of two classes from a third grade institution of the biomedical area, corresponding to the basic and advanced levels of the second term in 2006. The text has 24 NGs of different lexical content, a total of 27 NGs in the whole text summing up to 810 analyzed occurrences. The analysis is carried out at the morphologic, syntactic and semantic levels using as theoretical background the traditional and functional grammars (QUIRK et al, 1985; CELSE-MURCIA et al, 1998; TUCKER, 1998), in their semantic aspects, the Semantics (FRAWLEY, 1992) and the Cognitive Linguistics (TAYLOR, 2002). We concluded that the main difficulties were due to the lack of vocabulary and to the use of mother tongue strategies instead of using the top-down strategies for reading a text in English to compensate this gap. We also observed that even when the vocabulary was known, there were difficulties in establishing the semantic and syntactic relations between modifier and noun head. We suggested improvements for the teaching of reading English texts at the third grade grounded in the obtained results such as a more comprehensive study of the several different morphologic and syntactic structures of the NGs with premodifiers and their semantic consequences, an approach of the morphologic, syntactic and semantic aspects of the NGs and the use of both top-down and bottom-up strategies when reading a NG in the English language
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OBJETIVO: Analisar os efeitos de seis meses de intervenção de um programa de atividade física sobre os distúrbios neuropsiquiátricos e o desempenho nas atividades instrumentais da vida diária de idosos com Doença de Alzheimer (DA). MÉTODOS: Foram recrutados 20 pacientes nos estágios entre leve e moderado da DA. Segundo o escore clínico de demência (CDR), foram distribuídos em dois grupos: o grupo treinamento (GT), composto por dez mulheres que participaram de um program de exercícios físicos por um período de seis meses, e o grupo controle (GC), composto por dez outras participantes que não realizaram nenhum tipo de intervenção motora estruturada durante o mesmo período. Todas as participantes foram avaliadas por meio do Miniexame do Estado Mental, para obtenção da caracterização cognitiva; Inventário Neuropsiquiátrico, para identificação dos distúrbios neuropsiquiátricos mais prevalentes e Questionário de Atividades Instrumentais de Pfeffer, para verificação do grau de comprometimento funcional. RESULTADOS: Os participantes do GC mostraram uma deterioração tanto no desempenho das atividades instrumentais quanto na intensificação dos distúrbios neuropsiquiátricos, quando comparados os momentos pré e pós-intervenção. CONCLUSÃO: O GT demonstrou uma atenuação da intensificação dos distúrbios neuropsiquiátricos e do desempenho funcional em relação ao grupo sedentário.
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O efeito das variáveis independentes: soro desmineralizado em pó (0,0; 1,5 e 3,0 %), cultura láctica (1,0; 2,0 e 3,0 %) e temperatura de tratamento da mistura (85; 90 e 95°C) foi estudado nas respostas consistência sensorial e instrumental do iogurte. A metodologia de superfície de resposta foi usada para efetuar tratamentos estatísticos dos experimentos e desenvolver modelos matemáticos da relação entre as variáveis e as respostas. A consistência instrumental e sensorial apresentaram resultados semelhantes e correlacionáveis entre si, r = 0,65 (p < 0,01), ambas foram maiores quando aumentou-se a temperatura da mistura e diminuiu-se o teor de soro desmineralizado em pó.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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A padronização da textura é um dos principais problemas relacionados à qualidade da carne bovina. Por isso, a avaliação objetiva da maciez, por métodos mecânicos, vem sendo estudada há muitos anos. Para que a avaliação instrumental da textura seja uma ferramenta efetiva nos estudos envolvendo a maciez da carne, é necessário minimizar as causas de variação envolvidas na análise. Atualmente, a força de cisalhamento Warner-Bratzler é o método mais amplamente empregado para essa finalidade. O protocolo padrão dessa técnica analítica preconiza a utilização de uma lâmina de cisalhamento de 1,016mm de espessura. Neste trabalho, foram comparados dados de textura de carne bovina obtidos com a lâmina de cisalhamento padrão Warner-Bratzler, de 1,016mm de espessura, e uma lâmina mais grossa, de 3,05mm de espessura. Após o abate, amostras de músculo Longissimus dorsi, semelhantes em relação aos teores de umidade, lipídeos e proteínas, foram submetidas a duas diferentes temperaturas de resfriamento, atingindo diferentes velocidades de queda de temperatura e, consequentemente, diferentes graus de contração do tecido muscular, o que foi confirmado pela determinação do comprimento dos sarcômeros. Os resultados demonstraram uma maior sensibilidade da lâmina padrão Warner-Bratzler na detecção de variações da textura da carne, em função da velocidade de resfriamento.
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This work describes a method to determine Cu at wide range concentrations in a single run without need of further dilutions employing high-resolution continuum source flame atomic absorption spectrometry. Different atomic lines for Cu at 324. 754 nm, 327. 396 nm, 222. 570 nm, 249. 215 nm and 224. 426 nm were evaluated and main figures of merit established. Absorbance measurements at 324. 754 nm, 249. 215 nm and 224. 426 nm allows the determination of Cu in the 0. 07-5. 0 mg L -1, 5. 0-100 mg L -1 and 100-800 mg L -1 concentration intervals respectively with linear correlation coefficients better than 0. 998. Limits of detection were 21 μg L -1, 310 μg L -1 and 1400 μg L -1 for 324. 754 nm, 249. 215 nm and 224. 426 nm, respectively and relative standard deviations (n = 12) were ≤ 2. 7%. The proposed method was applied to water samples spiked with Cu and the results were in agreement at a 95% of confidence level (paired t-test) with those obtained by line-source flame atomic absorption spectrometry.
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Aim: To assess the contribution of a multimodal exercise program on the sleep disturbances (SD) and on the performance of instrumental activities daily living (IADL) in patients with clinical diagnosis of Alzheimer's disease (AD) and Parkinson's disease patients (PD). Methods: A total of 42 consecutive patients (23 training group, 19 control group) with PD and 35 demented patients with AD (19 trained group, 16 control group) were recruited. Participants in both training groups carried out three 1-h sessions per week of a multimodal exercise program for 6 months. The Pfeffer Questionnaire for Instrumental Activities and the Mini-Sleep Questionnaire were used to assess the effects of the program on IADL and SD respectively. Results: Two-way ancova showed interactions in IADL and SD. Significant improvements were observed for these variables in both intervention groups, and maintenance or worsening was observed in control groups. The analysis of effect size showed these improvements. Conclusion: The present study results show that a mild to moderate intensity of multimodal physical exercises carried out on a regular basis over 6 months can contribute to reducing IADL deficits and attenuating SD. © 2013 Japan Geriatrics Society.
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Instrumental texture analysis on extruded snacks is widely applied, however there is no scientific consensus about the test and probe types that can be correlated with the sensory texture of snacks. Eleven commercial extruded snacks of different shapes were evaluated instrumentally using different probes and sensorially through descriptive analysis. The snack texture was described using the attributes of hardness, crispness, adhesiveness, fracturability and chewiness. Cylindrical snacks were described through crispness and fracturability, pelleted and shell-shaped snacks by chewiness and ring-shaped snacks by adhesiveness and hardness. Hardness and adhesiveness were correlated with a Warner-Bratzler test using a V shape probe (r = 0.718 and r = 0.763, respectively), while fracturability and chewiness were correlated with a Warner-Bratzler test using a guillotine (r = 0.776 and r = 0.662, respectively). The fairly strong good correlations enable application of these instrumental tests as an indication of the sensory texture of extruded snacks. © 2013 Elsevier Ltd. All rights reserved.