12,589 research outputs found

    T-duality in Massive Integrable Field Theories: The Homogeneous and Complex sine-Gordon Models

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    The T-duality symmetries of a family of two-dimensional massive integrable field theories defined in terms of asymmetric gauged Wess-Zumino-Novikov-Witten actions modified by a potential are investigated. These theories are examples of massive non-linear sigma models and, in general, T-duality relates two different dual sigma models perturbed by the same potential. When the unperturbed theory is self-dual, the duality transformation relates two perturbations of the same sigma model involving different potentials. Examples of this type are provided by the Homogeneous sine-Gordon theories, associated with cosets of the form G/U(1)^r where G is a compact simple Lie group of rank r. They exhibit a duality transformation for each element of the Weyl group of G that relates two different phases of the model. On-shell, T-duality provides a map between the solutions to the equations of motion of the dual models that changes Noether soliton charges into topological ones. This map is carefully studied in the complex sine-Gordon model, where it motivates the construction of Bogomol'nyi-like bounds for the energy that provide a novel characterisation of the already known one-solitons solutions where their classical stability becomes explicit.Comment: 29 pages, LaTe

    Unlocking Community Engagement in REDD+ Initiatives: Insights from a Case Study in the Amazon

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    The literature on national plans to reduce emissions from deforestation and forest degradation REDD shows that the stakeholders present in the territory especially the communities are the focus of these actions The article questions the level of community engagement in a proposed REDD project in the Amazon by private companies with the aim of analyzing the socio-economic and environmental aspects of community residents The theoretical framework integrates stakeholder theory and community participation theory to support the analysis of the level of engagement 338 small rural producers were chosen from among the residents of 23 communities in four municipalities in the state of Par The sociodemographic characteristics were collected and structured in tables and graphs The results reveal that the communities are socially disjointed with problems defining property rights and access to government goods and services which makes it difficult to achieve the benefits declared by the REDD projec

    Azevedo Amaral e o século do corporativismo, de Michael Manoilesco, no Brasil de Vargas

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    Este artigo tem como objetivo de fundo acompanhar o processo de circulação e apropriação de ideias sobre o modelo corporativista de organização do Estado e da sociedade, no Brasil dos anos 1930/40. Para tanto, escolheu trabalhar com a atuação de um dos mais importantes intelectuais desse período: Azevedo Amaral. Este intelectual se dedicou a traduzir para o português, o livro de Michael Manoilesco, O século do corporativismo, do qual escreve o prefácio, em 1938. Nos anos 1930, produz também vários livros, entre os quais, O Estado autoritário e a realidade nacional, igualmente datado de 1938 e publicado pela editora José Olympio, no qual faz uma aposta imediata no modelo autoritário e corporativista de Estado para o Brasil

    Tail-anchored proteins at peroxisomes: identification of MIRO1 as a novel peroxisomal motility factor

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    Peroxisomes are dynamic and multifunctional organelles, which are essential for human health and development. They are remarkably diverse, with functions that vary significantly between cells and organisms, and can dramatically change their size, shape and dynamics in response to cellular cues. In the past few years, several studies have significantly increased our understanding of the basic principles that enable peroxisome biogenesis and degradation, as well as their pivotal role in cellular signalling and homeostasis. However, several of these processes are still poorly understood. In this thesis we initially studied the peroxisome targeting mechanism of a group of C-terminally anchored membrane proteins, known as tail-anchored (TA) proteins. In order to investigate the molecular signals that enable TA protein targeting to cellular organelles, we analysed the physicochemical properties of a cohort of TA proteins both in silico and in vivo, and show that a combination of transmembrane domain (TMD) hydrophobicity and C-terminal tail charge determines organelle-specific targeting. Focusing on peroxisomes, we demonstrate that a balance between TMD hydrophobicity and high positive tail charge directs TA proteins to this organelle, and enables binding to the peroxisomal chaperone PEX19. These results allowed us to create a bioinformatical tool to predict the targeting of uncharacterised TA proteins and further develop our understanding of the molecular mechanisms involved in the targeting of this protein group. From our initial TA protein screen, we identified the TA protein MIRO1 at peroxisomes and looked at its role in the regulation of peroxisome motility. We show that endogenous MIRO1 localises to mitochondria and peroxisomes, and that dual targeting depends on the C-terminal tail. MIRO1 expression significantly increased peroxisome motility in several cell lines, and revealed a role for motility in peroxisome dynamics, by inducing organelle proliferation and elongation. These results reveal a new molecular complex at peroxisomes and provide us with a tool to further dissect the role of motility on peroxisome function.University of Exete

    Dietary supplements with green tea marketed in Portugal: information on website, labels and antioxidant activity

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    The use of plants and their health benefits have been recognized over the years. Its use and consumption of herbal dietary supplements has increased in the last years in United States and Europe. Internet is one of the most required options to buy dietary supplements (DS). Several studies suggest that information on most sites is incomplete, poorly referenced, and may contain illegal claims. Thus, a conscious and informed decision is essential for consumers. Camellia s inensis , also known as green tea, is one of the most consumed plants worldwide and has been recognized by its antioxidant potential over the years. This activity can protect several diseases with an oxidative stress origin. For these reasons, a study was performed to evaluate the quality of information on websites selling dietary supplements with green tea. A modified DISCERN tool was used to evaluate websites from pharmacies/parapharmacies, websites from food health stores, and websites without physical space. Websites scored 1 or 2 at evaluation rating (Low – serious or extensive outcomes). These results reveal the importance of developing a checklist for the online marketing of herbal products, based on DISCERN instrument, or other. These instruments can guide health professionals, who have a very important role in directing patients to high-quality sources of information.Legal framework for dietary supplements varies among countries, and in Portugal, DS are regulated by the Direção Geral de Alimentação e Veterinária (DGAV). Although there are directives published by European Commission, in Portugal, decree-law are incomplete and DS safety is placed on the substance’s manufacturer or marketer. In addition, clinical trials are not required for DS in Portugal, which allows adulteration, falsification, contamination and incorrect labels. In Portugal, DS can be sold in pharmacies, parapharmacies, supermarkets, dietetic stores and online, and consumers should be able to make informed and appropriate health care choices. Also, consumers use DS labels (information provided on the packaging) and leaflets to further their understanding about some DS ingredients, relevant indication(s), directions for use, side effects, contraindications and drug-supplements interactions. For these reasons, another study was performed using an adapted form to evaluate legal and scientific information of twenty green tea DS sold in pharmacies, parapharmacies and health food stores in Portugal. From the legal and scientific points of view none of the websites fulfilled all the analyzed criteria. Seven DS (35.0%) had indications of use similar to those mentioned in the literature. Adverse reactions and drug interactions information were rarely provided by two and three DS, respectively. Green tea is a complex mixture of several constituents, which include phenolic compounds like catechins, flavonoids, and phenolic acids. This chemical composition is associated with antioxidant activity. Antioxidant products demand has been increasing over the last years. They are referenced as having a protective role in many diseases, like cancer, neurodegenerative and cardiovascular disorders. Considering the lack of legislation, in Portugal, that controls DS prior to its introduction in the market, the last aim of this thesis was to evaluate antioxidant activity of six green tea supplements (three isolated and three mixture of substances/plant extracts). This evaluation was performed by common assays, namely, DPPH, superoxide and Fe2+ chelating assays. Results showed that antioxidant activity depends on composition and concentration of each substance present in green tea’s DS. In addition, green tea DS studied showed different antioxidant results at different assays performed. These thesis results may contribute to understand the importance of quality information provided by websites selling DS, and also the importance of regulation regarding its manufacturing and selling

    Dyonic Integrable Models

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    A class of non abelian affine Toda models arising from the axial gauged two-loop WZW model is presented. Their zero curvature representation is constructed in terms of a graded Kac-Moody algebra. It is shown that the discrete multivacua structure of the potential together with non abelian nature of the zero grade subalgebra allows soliton solutions with non trivial electric and topological charges. The dressing transformation is employed to explicitly construct one and two soliton solutions and their bound states in terms of the tau functions. A discussion of the classical spectra of such solutions and the time delays are given in detail.Comment: Latex 30 pages, corrected some typo
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