yes / This paper critically analyzes the fiction-view of scientific modeling, which exploits presumed analogies between literary fiction and model building in science. The basic idea is that in both fiction and scientific modeling fictional worlds are created. The paper argues that the fiction-view comes closest to certain scientific thought experiments, especially those involving demons in science and to literary movements like naturalism. But the paper concludes that the dissimilarities prevail over the similarities. The fiction-view fails to do justice to the plurality of model types used in science; it fails to realize that a function like idealization only makes sense in science because models, unlike works of fiction, can be de-idealized; it fails to distinguish sufficiently between the make-believe (fictional) worlds created in fiction and the hypothetical (as-if) worlds envisaged in models. Representation characterized in the fiction-view as a license to draw inferences does not sufficiently distinguish between inferences in fiction from inferences in scientific modeling. To highlight the contrast the paper proposes to explicate representation in terms of satisfaction of constraints

The World Health Organization (WHO) states that 30,000 children under the age of five die each day worldwide. Around a quarter of these die from diarrheal disease caused by microbial infection. In addition to this high mortality rate, there are data emerging on the morbidity effects of diarrheal disease, for example a few episodes of diarrhea in the first two years of life can remove 10 IQ points and lead to growth deficiency. Vibrio cholerae, the causative agent of the diarrheal disease cholera, is a serious problem in third world countries, where sanitary and hygiene infrastructure is very poor, and claims several thousand lives every year. In order to better understand the pathogenicity regulation in V. cholerae, structural and functional investigations of a hypothetical protein family present in pathogenicity islands and a transcriptional regulator protein for DNA-binding were investigated. Two adjacent genes, vc1804 and vc1805, encode hypothetical proteins within the Vibrio pathogenicity island-2 (VPI-2) of Vibrio cholerae, and are part of a cluster of genes only present in pathogenic strains of the bacterium. Paralogous adjacent genes, vc0508 and vc0509, are also present within a second pathogenicity island, the Vibrio seventh pandemic island-2 (VSP-2), of V. cholerae O1 El Tor and O139 serogroup isolates. Sequence similarity suggests that the VC0508, VC0509, VC1804 and VC1805 proteins will share a similar fold. The crystal structures of VC0508, VC0509 and VC1805 have been determined to a resolution of 1.9, 2.4 and 2.1 Å, respectively. Several recombinant constructs of vc1804 were made, but no soluble proteins were expressed. This hypothetical protein family reveals structural homology to human mitochondrial protein p32. Human p32 is a promiscuous protein known to bind to a variety of partners including the globular head component of C1q. We have shown that VC1805 binds to C1q. One possibility is that VC1805 is involved in adherence of the bacterium to membrane-bound C1q in the gut. To explore the roles of VC0508, VC0509, VC1804 and VC1805 in vivo, gene knockout and animal model studies of those proteins are underway. The ferric uptake regulator (Fur), a metal-dependent DNA-binding protein, acts as both a repressor and activator of numerous genes involved in maintaining iron homeostasis in bacteria. It has also been demonstrated in Vibrio cholerae that Fur plays an additional role in pathogenesis, and this opens up the potential of Fur as a drug target for cholera. The first crystal structure of a Fur protein, from Pseudomonas aeruginosa, revealed a dimeric molecule with each monomer containing a dimerization domain, a helical DNA-binding domain and two metal binding sites: Zn1 is proposed to be a regulatory Fe-binding site, and Zn2 is proposed to be a structural Zn-binding site. Here we present the crystal structure of V. cholerae Fur (VcFur) that reveals a very different orientation of the DNA-binding domains. Accompanying these structural changes are alterations in the amino acids coordinating the zinc at the Zn2 site, and this lends support to this being the site regulated by iron. There is no evidence of metal binding to the cysteines that are conserved in many Fur homologues, including the much-studied E. coli Fur. An analysis of the metal binding properties shows that like other Fur proteins, VcFur can be activated by a range of divalent metals. EPR spectroscopy measurements of the movements of the DNA-binding domain, in the presence of DNA and different metals, are underway.

Orientador: Henrique Ferreira / Banca: Marco Aurélio Takita / Banca: Fernando Carlos Pagnocca / Resumo: O cancro cítrico é uma doença causada pela bactéria Xanthomonas axonopodis pv. citri (Xac), e que afeta plantas de citros por todo o mundo. O genoma de Xac foi completamente seqüenciado, o que revelou grandes quantidades de ORFs (~30%) codificando para produtos com função desconhecida (proteínas hipotéticas). Baseando-se no princípio de que muitos eventos bioquímicos acontecem em sítios específicos no interior celular, a localização de proteínas em fusão com GFP tem sido amplamente utilizada para a obtenção de informações valiosas a respeito de suas funções. Para iniciarmos estudos de localização de proteínas hipotéticas em Xac, construímos um vetor integrativo capaz de expressá-las em fusão com o polipeptídio GFP, pPM2a. O vetor de expressão para Xac carrega um cassete promotor/repressor de xilose (xylR/pxyl), o gene gfp, um RBS sintético e um fragmento do gene de α-amilase de Xac, para direcionar a integração do sistema de expressão no lócus amy do cromossomo bacteriano. Mostramos aqui a integração estável do vetor no lócus amy de Xac. Além disso, mutantes de Xac expressando o polipeptídio GFP não apresentam nenhuma alteração em seu fenótipo de patogenicidade para o hospedeiro (laranja doce). Mutantes de Xac expressando versões marcadas com GFP para as proteínas ParB e ZapA, ambas codificadas por Xac, foram utilizadas para a padronização dos estudos de localização subcelular. GFP-ZapAXac apresentou um padrão de localização análogo ao de seu ortólogo presente em Bacillus subtilis: uma estrutura semelhante a uma barra, posicionada no meio do bacilo, onde o septo se desenvolve, orientado perpendicularmente com relação ao eixo longitudinal da célula. Este é o primeiro relato de um estudo de localização realizado em Xac. Ao contrário de GFP-ZapAXac, ParBXac-GFP não mostrou nenhum padrão de localização, apesar de a fusão... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Citrus canker is a disease caused by the bacterium Xanthomonas axonopodis pv. citri (Xac), which affects citrus plants worldwide. The genome of Xac was completely sequenced, which unveiled an expressive amount of ORFs (~30%) coding for products of unknown function (hypothetical proteins). Based on the principle that many biochemical events happen at specific sites within the cells, protein localization studies have been extensively used to gather valuable information about function. In order to start subcellular localization studies of hypothetical proteins encoded by Xac using fluorescent microscopy, we constructed an integrative expression vector for GFP-tagging of proteins in this bacterium, pPM2a. The expression vector for Xac carries a xylose repressor/promoter cassette (xylR/pxyl), the gfp gene, a synthetic Ribosome Binding Site (RBS), and a fragment of the α-amylase gene of Xac, to drive the integration of the whole expression system into the amy locus of the bacterial chromosome. We show here stable integration of the expression vector into the amy locus of Xac. Furthermore, Xac mutants expressing the polypeptide GFP do not exhibit any alteration in pathogenicity to the host plant sweet orange. Mutants of Xac expressing GFPtagged versions of ParB and ZapA proteins, both encoded by Xac, were used to standardize the subcellular localization studies. GFP-ZapAXac showed a localization pattern analogous to its ortholog encoded by Bacillus subtilis: a bar-like structure positioned in the middle of the rods, where the septum develops, oriented perpendicularly to the longitudinal axis of the cell. This is the first report of a protein localization study performed in Xac Unlike GFP-ZapAXac, ParBXac-GFP did not display any detectable localization pattern, despite the fact that we were able to detect the production of the fusion ParBXac-GFP in Western blot experiments... (Complete abstract click electronic access below) / Mestre

Esse trabalho adota concepção de que o ensino de ciências deve dar condições para que o aluno possa aprender ciências, aprender sobre ciências e aprender a fazer ciências. Para tal, é importante pensar o ensino de ciências a partir da perspectiva da alfabetização científica, favorecendo o uso de situações investigativas e resoluções de problemas nos quais os alunos sejam iniciados nas práticas científicas escolares, se apropriando de práticas próprias da Ciência, tais como a linguagem e a construção coletiva do conhecimento. Neste contexto, acreditamos que a resolução de problemas em sequências didáticas investigativas de ecologia favorece a aprendizagem de conceitos e de etapas de como a ciência é construída, como o levantamento de hipóteses. Assim, dado que o levantamento de hipóteses é uma ação importante nas aulas de ciências, acreditamos que a averiguação desse momento da aula pode apontar indicadores de aulas investigativas. Assim, a questão de pesquisa deste trabalho é: \"Como as hipóteses escolares em sequências didáticas investigativas podem ser caracterizadas nas aulas de ciências? \" Para identificar as hipóteses utilizamos o padrão de raciocínio hipotético dedutivo e propomos características para hipóteses escolares considerando a sua função, estrutura, qualidade e conteúdo. Defendemos que a construção de hipóteses utilizando o raciocínio hipotético dedutivo nas aulas de ciências é importante para uma comunicação estruturada que usa a maneira lógica nos moldes do raciocínio cientifico, e que favorece ao aluno desenvolver habilidades próprias da comunidade científica como a apropriação da linguagem. As hipóteses escolares podem ser consideradas em dez características. Considerar as características da hipótese escolar é ir além do simples preenchimento dos elementos de raciocínio hipotético dedutivo, é avaliar a qualidade da hipótese que o aluno levanta. Isso ajuda no planejamento e execução de ações que auxiliem no aprendizado dos alunos pois indica quais as relações de ideias os alunos estão fazendo durante a resolução dos problemas e pode ser um indicador do eixo funcional da alfabetização científica. / This work adopts conception of which the sciences teaching must give conditions so that the pupil can learn sciences, learn on sciences and learn to do sciences. For such, the sciences teaching is important to think from the perspective of the scientific literacy, favoring the use of situations investigative and resolutions of problems into which the pupils are initiated in school scientific practices, appropriating of practices own to the Science, such as the language and the collective construction of the knowledge. In this context, we believe that the problems resolution in didactics sequences of ecology favors the apprenticeship of concepts and of steps of as the science is built, like the lifting hypothesis. Thus, since the hypothesis survey is an important action in the science classes, we believe that the investigation of this moment of the class can indicate indicators of investigative classes. Thus, the research question of this work is: \"How can school hypotheses in investigative didactic sequences be characterized in science classes?\" To identify the hypotheses we use the hypothetical deductive reasoning pattern and propose characteristics for school hypotheses considering their function, structure, quality and content. We argue that the construction of hypotheses using deductive hypothetical reasoning in science classes is important for a structured communication that uses the logical way in the scientific reasoning, and that favors the student to develop skills proper to the scientific community as the appropriation of language. The school hypotheses can be considered in ten characteristics. Consider the characteristics of the school hypothesis is to go beyond simply filling in the elements of hypothetical deductive reasoning, it is to evaluate the quality of the hypothesis that the student raises. This helps in the planning and execution of actions that aid in student learning because it indicates what ideas relationships students are doing during problem solving and can be an indicator of the functional axis of scientific literacy.

There are numerous studies that address the issue of discipline practices in schools. Within the last decade there have been an increasing number of scholars and school district personnel who have written about discipline, and more specifically, the discipline of specific populations of students such as African Americans. Although many of these studies address the disparate disciplinary practices that occur in many school districts, little attention is devoted to how students understand these practices in the larger context of their general school experiences. This research intends to fill the void in the literature that utilizes the experiences of students to understand inequitable discipline practices. The primary purpose of this study is to examine a selected group of "at-risk" African American male students' experiences and beliefs about disciplinary practices used in school.

No description available.

abstract: Zeolites are a class of microporous materials that are immensely useful as molecular sieves and catalysts. While there exist millions of hypothetical zeolite topologies, only 206 have been recognized to exist in nature, and the question remains: What distinguishes known zeolite topologies from their hypothetical counterparts? It has been found that all 206 of the known zeolites can be represented as networks of rigid perfect tetrahedra that hinge freely at the connected corners. The range of configurations over which the corresponding geometric constraints can be met has been termed the "flexibility window". Only a small percentage of hypothetical types exhibit a flexibility window, and it is thus proposed that this simple geometric property, the existence of a flexibility window, provides a reliable benchmark for distinguishing potentially realizable hypothetical structures from their infeasible counterparts. As a first approximation of the behavior of real zeolite materials, the flexibility window provides additional useful insights into structure and composition. In this thesis, various methods for locating and exploring the flexibility window are discussed. Also examined is the assumption that the tetrahedral corners are force-free. This is a reasonable approximation in silicates for Si-O-Si angles above ~135°. However, the approximation is poor for germanates, where Ge-O-Ge angles are constrained to the range ~120°-145°. Lastly, a class of interesting low-density hypothetical zeolites is evaluated based on the feasibility criteria introduced. / Dissertation/Thesis / Ph.D. Physics 2013

Esse trabalho adota concepção de que o ensino de ciências deve dar condições para que o aluno possa aprender ciências, aprender sobre ciências e aprender a fazer ciências. Para tal, é importante pensar o ensino de ciências a partir da perspectiva da alfabetização científica, favorecendo o uso de situações investigativas e resoluções de problemas nos quais os alunos sejam iniciados nas práticas científicas escolares, se apropriando de práticas próprias da Ciência, tais como a linguagem e a construção coletiva do conhecimento. Neste contexto, acreditamos que a resolução de problemas em sequências didáticas investigativas de ecologia favorece a aprendizagem de conceitos e de etapas de como a ciência é construída, como o levantamento de hipóteses. Assim, dado que o levantamento de hipóteses é uma ação importante nas aulas de ciências, acreditamos que a averiguação desse momento da aula pode apontar indicadores de aulas investigativas. Assim, a questão de pesquisa deste trabalho é: \"Como as hipóteses escolares em sequências didáticas investigativas podem ser caracterizadas nas aulas de ciências? \" Para identificar as hipóteses utilizamos o padrão de raciocínio hipotético dedutivo e propomos características para hipóteses escolares considerando a sua função, estrutura, qualidade e conteúdo. Defendemos que a construção de hipóteses utilizando o raciocínio hipotético dedutivo nas aulas de ciências é importante para uma comunicação estruturada que usa a maneira lógica nos moldes do raciocínio cientifico, e que favorece ao aluno desenvolver habilidades próprias da comunidade científica como a apropriação da linguagem. As hipóteses escolares podem ser consideradas em dez características. Considerar as características da hipótese escolar é ir além do simples preenchimento dos elementos de raciocínio hipotético dedutivo, é avaliar a qualidade da hipótese que o aluno levanta. Isso ajuda no planejamento e execução de ações que auxiliem no aprendizado dos alunos pois indica quais as relações de ideias os alunos estão fazendo durante a resolução dos problemas e pode ser um indicador do eixo funcional da alfabetização científica. / This work adopts conception of which the sciences teaching must give conditions so that the pupil can learn sciences, learn on sciences and learn to do sciences. For such, the sciences teaching is important to think from the perspective of the scientific literacy, favoring the use of situations investigative and resolutions of problems into which the pupils are initiated in school scientific practices, appropriating of practices own to the Science, such as the language and the collective construction of the knowledge. In this context, we believe that the problems resolution in didactics sequences of ecology favors the apprenticeship of concepts and of steps of as the science is built, like the lifting hypothesis. Thus, since the hypothesis survey is an important action in the science classes, we believe that the investigation of this moment of the class can indicate indicators of investigative classes. Thus, the research question of this work is: \"How can school hypotheses in investigative didactic sequences be characterized in science classes?\" To identify the hypotheses we use the hypothetical deductive reasoning pattern and propose characteristics for school hypotheses considering their function, structure, quality and content. We argue that the construction of hypotheses using deductive hypothetical reasoning in science classes is important for a structured communication that uses the logical way in the scientific reasoning, and that favors the student to develop skills proper to the scientific community as the appropriation of language. The school hypotheses can be considered in ten characteristics. Consider the characteristics of the school hypothesis is to go beyond simply filling in the elements of hypothetical deductive reasoning, it is to evaluate the quality of the hypothesis that the student raises. This helps in the planning and execution of actions that aid in student learning because it indicates what ideas relationships students are doing during problem solving and can be an indicator of the functional axis of scientific literacy.

Contingent Valuation (CV) methods are a primary tool in environmental economics to ascertain non-use or other values not observable through existing market mechanisms. Because common CV approaches typically rely on hypothetical answers from surveys in order to generate welfare estimates, these are often labelled stated preferences. Results from stated preference methods often diverge from those obtained when actual preference or behavior are involved. This divergence is commonly known as Hypothetical Bias (HB). This dissertation addresses HB as it applies to environmental applications. To begin, a meta-analysis using a sample of studies many times larger than previous works was performed. Its results identify which study protocols exacerbate HB, and which may mitigate it. Furthermore, the meta-analysis establishes the efficacy of some popular techniques to mitigate HB. The second essay focuses on understanding and addressing two important topics to environmental economics, distance decay and charismatic species conservation. These effects have not been investigated with respect to HB. We implement a field survey of monarch and viceroy butterfly conservation, creating survey treatment conditions involving both real payment and hypothetical scenarios in order to establish the extent of HB. The key finding is that while HB is present for both butterflies, HB in distance decay exists for monarchs. There is also additional HB for monarchs compared to viceroys, which we attribute to the former’s charisma. The final endeavor studies the usefulness of consequentiality, a relatively new tactic to reduce HB. Consequentiality is the degree to which respondents believe their answers may affect policy outcomes. Relying on the monarch field survey, we find that using a technique known as ex ante consequentiality may exacerbate HB. Another approach known as ex post consequentiality is more effective at reducing the extent of HB in the data. Lastly, some elements of the studies’ results showcase that HB is not always present and can also explain some of the mixed results found on the efficacy of HB mitigating methods reported in previous studies.

Syftet med studien är att kartlägga talbaserade och sifferbaserade räknemetoder i subtraktion genom en läromedelsanalys av läromedlet Koll på matematik för årskurs 1-3. Studien ämnar till att undersöka i vilken ordning räknemetoderna introduceras samt att urskilja hur undervisningen av dessa utformas utifrån läromedlet. Studiens teoretiska perspektiv, hypothetical learning trajectory, kopplas samman med Skotts analysmodell för att kartlägga räknemetoderna i läromedlet. Resultatet visar att undervisningen av skriftliga räknemetoder i subtraktion utifrån läromedlet Koll på matematik sker på olika sätt beroende på årskurs, men liknande mönster går att urskilja. Inledande gemensamma samtal, stöttning, illustrationer, samt konkret material förekommer i alla årskurser men en övergripande regression av kvantitet sker i stigande årskurser. Det framgår även att talbaserade metoder är de som introduceras först och sifferbaserade metoder introduceras tidigast i elevbok 2B. En diskussion förs innan slutsatsen utmynnar i att tidigare forskning påvisar att talbaserade metoder bör introduceras tidigare än sifferbaserade metoder, vilket också är den ordning läromedlet introducerar räknemetoderna.