Acidez do solo e calagem em pomares de frutíferas tropicais

A produtividade agrícola nos trópicos é afetada, principalmente, pelos fatores ligados à acidez do solo (pH, saturação por bases, acidez potencial, disponibilidade de nutrientes). A calagem é uma prática bem conhecida para corrigir a acidez do solo em culturas anuais, ainda que não seja praticada com a regularidade necessária. Entretanto, em culturas perenes, a incorporação de corretivos é mais complexa, devido às características desse grupo de plantas e à carência de informações científicas sobre o assunto. em condições de acidez, a calagem promove a neutralização do Al3+, a elevação do pH e o fornecimento de Ca e Mg, possibilitando a proliferação de raízes, com reflexos positivos no crescimento da parte aérea das plantas. Contudo, devido à baixa solubilidade e à lenta movimentação do calcário ao longo do perfil do solo, há obrigatoriedade de se fazer distribuição uniforme e incorporação profunda, antecedendo a implantação do pomar, a fim de garantir o eficiente aproveitamento de água e de nutrientes contidos nessas camadas. A calagem deve ser considerada um investimento, pois seus benefícios perduram além de um ano ou de uma safra agrícola. Isso se deve ao efeito residual dos corretivos de acidez do solo, sendo o tempo de duração desse efeito dependente de vários fatores, entre os quais: condições edafoclimáticas, cultura, manejo da área e tipo de corretivo empregado. em geral, partículas maiores de calcário têm efeito residual mais prolongado, sendo empregadas na implantação dos pomares. No entanto, a relação entre o tamanho da partícula e o efeito residual tem sido pouco pesquisada, devido à necessidade de estudos de longa duração. em função das elevadas doses de adubos nitrogenados utilizadas nos pomares de altos rendimentos, a acidez do solo aumenta, como resultado do processo de nitrificação. em pomares já implantados, o procedimento atualmente utilizado pelos produtores é a incorporação superficial do calcário na área. As recomendações talvez fossem outras, caso houvesse maior subsídio da pesquisa, tendo em vista os diversos problemas fitossanitários que podem ocorrer, direta ou indiretamente da prática da incorporação do corretivo, tais como redução do sistema radicular, ferimento das raízes e consequente risco de infecções, com disseminação de pragas e doenças no pomar. O objetivo desta revisão é apresentar os principais resultados de pesquisas sobre o assunto, mostrando os efeitos da calagem sobre a fertilidade do solo, a nutrição e a produtividade de frutíferas de grande importância econômica para o Brasil, bem como discutir a duração do efeito residual dos corretivos e a dose mais ecônomica a ser aplicada nos pomares de frutas em implantação e em produção.

Mecanismos de controle do trabalho escolar em propostas de escrita narrativa em livros didáticos de português (1974-2009)

This essay aims at investigating the writing proposals of Portuguese textbooks (LDP Livros Didáticos de Português) for Middle School (EF Ensino Fundamental), from 6th to 9th grade, from the 70s to 2009. It aims to check, though the discourse reported in the Portuguese Textbook, the control directed to the practice of the teacher and the student to do in the teaching situations. Theoretically, we search for contributions that come from the Discourse Analysis of French filiation, so we can analyze the ideological constructions present in the discourse of the ―LDP‖ more specific lly the control directed to the te cher nd student the users of the book, in writing activities. It started from a corpus of 63 textbooks whereof the following steps were performed: a) mapping of the writing proposals contemplated in the ―LDP‖ of high school; b cutting in the selection of propos l ccording to the rese rch go ls intended (writing proposals of narrative texts). After mapping the writing proposals presented in the ―LDP‖ bout the criteri mentioned bove we re d the writing propos ls to ch rt the quantity of proposals of textual writing productions in each textbook (which usually follows a pattern : 12 chapters and, at the end, the writing proposal. Nevertheless, some books present 2 (two) or more writing proposals at the end of each chapter). We did a cutting in the corpus initi lly constituted 63 ―LDP‖ nd we selected 12 writing proposals of narrative texts presented in the ―LDPs‖ to present wh t we intend to n lyze. Then, we separated these proposals into two groups: 1) activities which present ―instruction guide‖ to be followed by the student; 2) writing activities that allow the student write with no need to follow a text pattern, i.e., which encourage authorship. By means of analyses, it was possible to demonstrate that, in the Basic School, generally, the writing practices concentrate, primarily, on copying activities, reproduction, rewriting and, in more advanced levels, in activities that which start from preset models, asking the students to produce text with similar themes, following the suggested structure. It is about ideals that are supposed to be followed and imitated by the students, depriving them to assume their authorship. In order to insert the student in the world of writing it s necess ry to go beyond the model of c nonic l texts pr ctice th t puts the students f r from the possibility to be ― uthors‖. In contr st to this tendency, we face, nowadays, proposals that prioritize the authorship, the creation of a style

O Aleph e seus duplos: mimesis e auto-reflexividade na obra de Jorge Luis Borges

This study approach the Jorge Luis Borges s prose of fiction under the perspective of mimesis and the self-reflexivity. The hypothesis is that the Aleph is a central symbol of the Borges s fictional universe. The rewriting and the retake of this symbol along of his work entail to a reflection about the possibilities and the limits of mimesis. This study is divided in three parts which contain two chapters. The first part Bibliographic revision and conceptual fundaments of inquiry discuss the critical fortune of author (Chapter 1) and the concepts that will give sustentation to the inquiry (Chapter 2). The second part About the Borges s aesthetic project sketch out the literary project defended by Borges that is his conception of the literature and his ideological matrix (Chapter 3) beside his anti-psychologism and his nostalgia of epos (Chapter 4). The third and last part is entitled The Aleph and his doubles. In the chapter 5 this study analyses the short story El Aleph and consider its centrality on the Borges s work. The argument that is on this short story Borges elaborates a reflection about mimesis. In the chapter 6, on the same hand, four short stories will be analysed: Funes el memorioso ; El Libro de Arena ; El evangelio según Marcos and Del rigor en la ciencia . The conclusion that is the Borges s literature is self-awake of its process as such demonstrate its parodic sense and its bookish origin. Hence, the Borges s literature overlapping the mimetic crisis of language and challenge the limits between fiction and reality. However, it doesn t surrender to the nihilist perspective that is closing of literature to the world

Fundamentos da filosofia moral de Peter Singer

This research aims to reconstruct and explain the argument proposed by Peter Singer to justify the principle of equal consideration of interests (PECI). The PECI is the basic normative principle according to people should consider the interests of all sentient beings affected when somebody taking a moral decision. It is the join that Singer proposes between universalizability and the principle of equal consideration of interests that constitutes a compelling reason to justify it. The universalizability requires to disregard the numerical differences, putting yourself in other people s shoes, and to consider preferences, interests, desires and ideals of those affected. Singer joins universalizability to normative principle and molds the form and content of his theory. The first chapter introduces the discussion will be developed in this essay. The second chapter deals the historical and philosophical viewpoint from which Singer starts his studies. The third chapter is about the Singer s critiques of naturalism, intuitionism, relativism, simple subjectivism and emotivism. The fourth chapter exposes the design of universal prescriptivism proposed by R. M. Hare. The universal prescriptivism indicates, in the Singer s viewpoint, a consistent way to create the join between the universalizability and PECI. It highlights also the criticism designed by J. L. Mackie and Singer himself to universal prescriptivism. The second part of this chapter shows briefly some of the main points of the classical conception of utilitarianism and its possible relationship with the theory of Singer. The fifth chapter introduces the Singer s thesis about the origin of ethics and the universalizability as a feature necessary to the point of view of ethic, and the way which this argument is developed to form the PECI. The sixth chapter exposes the main distinctions that characterize the PECI. Finally the seventh chapter provides a discussion about the reasons highlighted by Singer for one who wants orient his life according to the standpoint of ethics. This structure allows explaining the main ideas of the author concerning the theoretical foundations of his moral philosophy

Os conceitos de eletricidade vítrea e eletricidade resinosa segundo Du Fay

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genética e biologia reprodutiva de vriesea minarum (Bromeliaceae): em busca de estratégias de conservação no quadrilátero ferrífero, minas gerais

Vriesea minarum is a rupiculous bromeliad species, with naturally fragmented populations, restricted to the Iron Quadrangle, Minas Gerais, Brazil. It is a threatened species, which is suffering from habitat loss due to the growth of cities and mining activities. The knowledge of genetic variability in plant populations is one of the main branches of conservation genetics, linking genetic data to conservation strategies while the knowledge about plant reproductive biology can aid in understanding key aspects of their life story, as well as in the comprehension of their distribution and survival strategies. Thus, the study of diversity, richness, and genetic structure, as well as the reproductive biology of populations of V. minarum can contribute to the development of conservation actions. Chapter 1 presents the transferability of 14 microsatellite loci for V. minarum. Among the results of this chapter, we highlight the successful transferability of 10 microsatellite loci described for other species of Bromeliaceae, all of which are polymorphic. In Chapter 2, we present the genetic analyses of 12 populations of V. minarum that are distributed throughout the Iron Quadrangle. We used the 10 microsatellite loci tested in Chapter 1. The results show a low population structuring (Fst = 0.088), but with different values of genetic richness (mean = 2.566) and gene diversity (mean = 0.635) for all populations; and a high inbreeding coefficient (Gis = 0.376). These may be the result of pollinators action and/or efficient seed dispersal, thus allowing a high connectivity among populations of naturally fragmented outcrops. The reproductive biology and floral morphology of a population of V. minarum, located in the Parque Estadual da Serra do Rola-Moça, are studied in Chapter 3. This reserve is the only public environmental protection area where the species occurs. As a result of field experiments and observations, we found that the species has its flowering period from January to March, with flowers that last for two days and that it has a mixed pollination syndrome. It is primarily alogamous, but also has the capacity to be self-ferilized. It is expected that data obtained in chapters 1, 2 and 3 serve as basis for other studies with species from the ferruginous rocky fields, since until now, to our knowledge, there are no other survey of endemic species from the Iron Quadrangle, seeking to merge the genetic knowledge, with the data of the reproductive biology, with the ultimate aim of biodiversity conservation. Considering the great habitat loss for the species by mining, it becomes crucial to analyze the creation of new protected areas for its conservation

Foreign Direct Investment in Latin America and the Caribbean 2008

Includes bibliography

Foreign Investment in Latin America and the Caribbean 1998

Includes bibliography

Latin America and the Caribbean in the World Economy 2001-2002

Includes bibliography

Latin America and the Caribbean in the World Economy 2004: 2005 trends

Includes bibliography

Latin America and the Caribbean in the World Economy 2000-2001

Includes bibliography

Globalization and development

Includes bibliography

Structural change and productivity growth, 20 years later: old problems, new opportunities

Includes bibliography

Pension reform in Europe in the 90's and lessons for Latin America

Includes bibliography

Stress distribution in ceramic restorations over natural tooth using finite element analysis. lithium disilicate x aluminum oxide material

Background: Data on stress distribution in tooth-restoration interface with different ceramic restorative materials are limited. The aim of this chapter was to assess the stress distribution in the interface of ceramic restorations with laminate veneer or full-coverage crown with two different materials (lithium dissilicate and densely sintered aluminum oxide) under different loading areas through finite element analysis. Materials and Methods: Six two-dimensional finite element models were fabricated with different restorations on natural tooth: laminate veneer (IPS Empress, IPS Empress Esthetic and Procera AllCeram) or full-coverage crown (IPS e.max Press and Procera AllCeram). Two different loading areas (L) (50N) were also determined: palatal surface at 45° in relation to the long axis of tooth (L1) and perpendicular to the incisal edge (L2). A model with higid natural tooth was used as control. von Mises equivalent stress (σ vM) and maximum principal stress (σ max) were obtained on Ansys software. Results: The presence of ceramic restoration increased σ vM and σ max in the adhesive interface, mainly for the aluminum oxide (Procera AllCeram system) restorations. The full-coverage crowns generated higher stress in the adhesive interface under L1 while the same result was observed for the laminate veneers under L2. Conclusions: Lithium dissilicate and densely sintered aluminum oxide restorations exhibit different behavior due to different mechanical properties and loading conditions. © 2011 Nova Science Publishers, Inc.